feat(push): gate relay delivery on operator consent (#2984 )

fix(forward): make an @silent comment silence the forward too (#2983 )
fix(app-proxy): trust the Play app signing certificate (#2982 )
2026-10-10 04:32:34 +09:00 · 2026-09-27 20:33:10 +02:00 · 2026-09-27 20:13:14 +02:00 · 2026-09-27 19:37:40 +02:00 · 2026-09-27 16:18:01 +02:00 · 2026-09-27 13:33:22 +02:00
412 changed files with 46953 additions and 21626 deletions
@@ -32,6 +32,7 @@
 /fluxer_docs/.astro/
 /fluxer_app/.devserver-cache.json
 /fluxer_app/pkgs/libfluxcore/
+/fluxer_app/pkgs/libfluxwebp/
 /fluxer_app/src/features/i18n/locales/*/messages.mjs
 /fluxer_app/src/features/messaging/utils/markdown/parser/MarkdownParserWasmBytes.ts
 /fluxer_app/src/features/theme/styles/generated/
@@ -123,12 +123,16 @@ jobs:
        with:
          path: |
            fluxer_app/pkgs/libfluxcore
+            fluxer_app/pkgs/libfluxwebp
            fluxer_app/src/features/messaging/utils/markdown/parser/MarkdownParserWasmBytes.ts
          key: >-
            app-wasm-${{ runner.os }}-1.98.1-${{ hashFiles('Cargo.lock', 'tools/ci/src/app_wasm.rs',
            'tools/ci/templates/libfluxcore_wrapper.js', 'tools/ci/templates/libfluxcore_wrapper.d.ts',
            'fluxer_app/rust/libfluxcore/Cargo.toml', 'fluxer_app/rust/libfluxcore/Cargo.lock',
            'fluxer_app/rust/libfluxcore/.cargo/config.toml', 'fluxer_app/rust/libfluxcore/src/**',
+            'fluxer_app/rust/libfluxwebp/Cargo.toml', 'fluxer_app/rust/libfluxwebp/Cargo.lock',
+            'fluxer_app/rust/libfluxwebp/src/**', 'fluxer_app/rust/libfluxwebp/shim/**',
+            'fluxer_app/rust/libfluxwebp/simd/**',
            'packages/markdown_parser/rust/Cargo.toml', 'packages/markdown_parser/rust/.cargo/config.toml',
            'packages/markdown_parser/rust/src/**') }}

@@ -142,12 +146,16 @@ jobs:
        with:
          path: |
            fluxer_app/pkgs/libfluxcore
+            fluxer_app/pkgs/libfluxwebp
            fluxer_app/src/features/messaging/utils/markdown/parser/MarkdownParserWasmBytes.ts
          key: >-
            app-wasm-${{ runner.os }}-1.98.1-${{ hashFiles('Cargo.lock', 'tools/ci/src/app_wasm.rs',
            'tools/ci/templates/libfluxcore_wrapper.js', 'tools/ci/templates/libfluxcore_wrapper.d.ts',
            'fluxer_app/rust/libfluxcore/Cargo.toml', 'fluxer_app/rust/libfluxcore/Cargo.lock',
            'fluxer_app/rust/libfluxcore/.cargo/config.toml', 'fluxer_app/rust/libfluxcore/src/**',
+            'fluxer_app/rust/libfluxwebp/Cargo.toml', 'fluxer_app/rust/libfluxwebp/Cargo.lock',
+            'fluxer_app/rust/libfluxwebp/src/**', 'fluxer_app/rust/libfluxwebp/shim/**',
+            'fluxer_app/rust/libfluxwebp/simd/**',
            'packages/markdown_parser/rust/Cargo.toml', 'packages/markdown_parser/rust/.cargo/config.toml',
            'packages/markdown_parser/rust/src/**') }}

@@ -190,6 +198,9 @@ jobs:
      - name: Check Rust dependencies
        run: cargo deny --locked check -D warnings

+      - name: Check libfluxwebp dependencies
+        run: cargo deny --manifest-path fluxer_app/rust/libfluxwebp/Cargo.toml --config deny.toml --locked check licenses bans sources
+
      - name: Check desktop native dependencies
        run: tools/ci/check-desktop-native-workspaces.sh dependencies

@@ -242,6 +253,9 @@ jobs:
      - name: Check formatting
        run: cargo fmt --all -- --check

+      - name: Check formatting (libfluxwebp)
+        run: cargo fmt --manifest-path fluxer_app/rust/libfluxwebp/Cargo.toml -- --check
+
      - name: Check formatting (desktop native workspaces)
        run: tools/ci/check-desktop-native-workspaces.sh fmt

@@ -398,12 +412,16 @@ jobs:
        with:
          path: |
            fluxer_app/pkgs/libfluxcore
+            fluxer_app/pkgs/libfluxwebp
            fluxer_app/src/features/messaging/utils/markdown/parser/MarkdownParserWasmBytes.ts
          key: >-
            app-wasm-${{ runner.os }}-1.98.1-${{ hashFiles('Cargo.lock', 'tools/ci/src/app_wasm.rs',
            'tools/ci/templates/libfluxcore_wrapper.js', 'tools/ci/templates/libfluxcore_wrapper.d.ts',
            'fluxer_app/rust/libfluxcore/Cargo.toml', 'fluxer_app/rust/libfluxcore/Cargo.lock',
            'fluxer_app/rust/libfluxcore/.cargo/config.toml', 'fluxer_app/rust/libfluxcore/src/**',
+            'fluxer_app/rust/libfluxwebp/Cargo.toml', 'fluxer_app/rust/libfluxwebp/Cargo.lock',
+            'fluxer_app/rust/libfluxwebp/src/**', 'fluxer_app/rust/libfluxwebp/shim/**',
+            'fluxer_app/rust/libfluxwebp/simd/**',
            'packages/markdown_parser/rust/Cargo.toml', 'packages/markdown_parser/rust/.cargo/config.toml',
            'packages/markdown_parser/rust/src/**') }}

@@ -417,12 +435,16 @@ jobs:
        with:
          path: |
            fluxer_app/pkgs/libfluxcore
+            fluxer_app/pkgs/libfluxwebp
            fluxer_app/src/features/messaging/utils/markdown/parser/MarkdownParserWasmBytes.ts
          key: >-
            app-wasm-${{ runner.os }}-1.98.1-${{ hashFiles('Cargo.lock', 'tools/ci/src/app_wasm.rs',
            'tools/ci/templates/libfluxcore_wrapper.js', 'tools/ci/templates/libfluxcore_wrapper.d.ts',
            'fluxer_app/rust/libfluxcore/Cargo.toml', 'fluxer_app/rust/libfluxcore/Cargo.lock',
            'fluxer_app/rust/libfluxcore/.cargo/config.toml', 'fluxer_app/rust/libfluxcore/src/**',
+            'fluxer_app/rust/libfluxwebp/Cargo.toml', 'fluxer_app/rust/libfluxwebp/Cargo.lock',
+            'fluxer_app/rust/libfluxwebp/src/**', 'fluxer_app/rust/libfluxwebp/shim/**',
+            'fluxer_app/rust/libfluxwebp/simd/**',
            'packages/markdown_parser/rust/Cargo.toml', 'packages/markdown_parser/rust/.cargo/config.toml',
            'packages/markdown_parser/rust/src/**') }}

@@ -26,6 +26,7 @@

 /fluxer_app/.devserver-cache.json
 /fluxer_app/pkgs/libfluxcore/
+/fluxer_app/pkgs/libfluxwebp/
 /fluxer_app/src/features/i18n/locales/*/messages.mjs
 /fluxer_app/src/features/messaging/utils/markdown/parser/MarkdownParserWasmBytes.ts
 /fluxer_app/src/features/theme/styles/generated/
@@ -10525,6 +10525,7 @@
 					"gateway_rollout": {"$ref": "#/components/schemas/GatewayRolloutConfigResponse"},
 					"voice_noise_suppression": {"$ref": "#/components/schemas/VoiceNoiseSuppressionConfigResponse"},
 					"push_service_delivery": {"$ref": "#/components/schemas/PushServiceDeliveryConfigResponse"},
+					"domain_migration": {"$ref": "#/components/schemas/DomainMigrationConfigResponse"},
 					"experiment_delivery": {"$ref": "#/components/schemas/ExperimentDeliveryConfigResponse"},
 					"registration": {
 						"type": "object",
@@ -10953,6 +10954,7 @@
 					"gateway_rollout",
 					"voice_noise_suppression",
 					"push_service_delivery",
+					"domain_migration",
 					"experiment_delivery",
 					"registration",
 					"self_hosted",
@@ -11091,6 +11093,10 @@
 						"nullable": true,
 						"allOf": [{"$ref": "#/components/schemas/PushServiceDeliveryConfigUpdateRequest"}]
 					},
+					"domain_migration": {
+						"nullable": true,
+						"allOf": [{"$ref": "#/components/schemas/DomainMigrationConfigUpdateRequest"}]
+					},
 					"experiment_delivery": {
 						"nullable": true,
 						"allOf": [{"$ref": "#/components/schemas/ExperimentDeliveryConfigUpdateRequest"}]
@@ -15184,6 +15190,26 @@
 					"poll_jitter_percent": {"type": "integer", "minimum": 0, "maximum": 50}
 				}
 			},
+			"DomainMigrationConfigUpdateRequest": {
+				"type": "object",
+				"properties": {
+					"enabled": {"type": "boolean"},
+					"rollout_basis_points": {"type": "integer", "minimum": 0, "maximum": 10000},
+					"rollout_salt": {"type": "string", "minLength": 1, "maxLength": 64, "pattern": "^[\\x20-\\x7e]+$"},
+					"included_user_ids": {
+						"maxItems": 1000,
+						"type": "array",
+						"items": {"type": "string", "pattern": "^\\d{1,20}$"}
+					},
+					"excluded_user_ids": {
+						"maxItems": 1000,
+						"type": "array",
+						"items": {"type": "string", "pattern": "^\\d{1,20}$"}
+					},
+					"anonymous_rollout_basis_points": {"type": "integer", "minimum": 0, "maximum": 10000},
+					"standalone_forwarding": {"type": "boolean"}
+				}
+			},
 			"PushServiceDeliveryConfigUpdateRequest": {
 				"type": "object",
 				"properties": {
@@ -15199,7 +15225,8 @@
 						"maxItems": 1000,
 						"type": "array",
 						"items": {"type": "string", "pattern": "^\\d{1,20}$"}
-					}
+					},
+					"relay_consent_accepted": {"type": "boolean"}
 				}
 			},
 			"VoiceNoiseSuppressionConfigUpdateRequest": {
@@ -15267,6 +15294,46 @@
 				"required": ["poll_interval_seconds", "poll_jitter_percent"],
 				"additionalProperties": false
 			},
+			"DomainMigrationConfigResponse": {
+				"type": "object",
+				"properties": {
+					"enabled": {"default": false, "type": "boolean"},
+					"config_version": {"default": 0, "type": "integer", "minimum": 0, "maximum": 9007199254740991},
+					"rollout_basis_points": {"default": 0, "type": "integer", "minimum": 0, "maximum": 10000},
+					"rollout_salt": {
+						"default": "domain-migration-v1",
+						"type": "string",
+						"minLength": 1,
+						"maxLength": 64,
+						"pattern": "^[\\x20-\\x7e]+$"
+					},
+					"included_user_ids": {
+						"default": [],
+						"maxItems": 1000,
+						"type": "array",
+						"items": {"type": "string", "pattern": "^\\d{1,20}$"}
+					},
+					"excluded_user_ids": {
+						"default": [],
+						"maxItems": 1000,
+						"type": "array",
+						"items": {"type": "string", "pattern": "^\\d{1,20}$"}
+					},
+					"anonymous_rollout_basis_points": {"default": 0, "type": "integer", "minimum": 0, "maximum": 10000},
+					"standalone_forwarding": {"default": false, "type": "boolean"}
+				},
+				"required": [
+					"enabled",
+					"config_version",
+					"rollout_basis_points",
+					"rollout_salt",
+					"included_user_ids",
+					"excluded_user_ids",
+					"anonymous_rollout_basis_points",
+					"standalone_forwarding"
+				],
+				"additionalProperties": false
+			},
 			"PushServiceDeliveryConfigResponse": {
 				"type": "object",
 				"properties": {
@@ -15291,7 +15358,16 @@
 						"maxItems": 1000,
 						"type": "array",
 						"items": {"type": "string", "pattern": "^\\d{1,20}$"}
-					}
+					},
+					"relay_consent_accepted": {"default": false, "type": "boolean"},
+					"relay_consent_accepted_at": {
+						"default": null,
+						"nullable": true,
+						"type": "string",
+						"format": "date-time",
+						"pattern": "^(?:(?:\\d\\d[2468][048]|\\d\\d[13579][26]|\\d\\d0[48]|[02468][048]00|[13579][26]00)-02-29|\\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\\d|30)|(?:02)-(?:0[1-9]|1\\d|2[0-8])))T(?:(?:[01]\\d|2[0-3]):[0-5]\\d:[0-5]\\d(?:\\.\\d+)?(?:Z))$"
+					},
+					"relay_consent_accepted_by": {"default": null, "nullable": true, "type": "string", "pattern": "^\\d{1,20}$"}
 				},
 				"required": [
 					"enabled",
@@ -15299,7 +15375,10 @@
 					"rollout_basis_points",
 					"rollout_salt",
 					"included_user_ids",
-					"excluded_user_ids"
+					"excluded_user_ids",
+					"relay_consent_accepted",
+					"relay_consent_accepted_at",
+					"relay_consent_accepted_by"
 				],
 				"additionalProperties": false
 			},
@@ -15645,9 +15724,10 @@
 					"id": {"type": "string", "description": "The credential ID"},
 					"name": {"type": "string", "description": "User-assigned name for the credential"},
 					"created_at": {"type": "string", "description": "When the credential was registered"},
-					"last_used_at": {"nullable": true, "description": "When the credential was last used", "type": "string"}
+					"last_used_at": {"nullable": true, "description": "When the credential was last used", "type": "string"},
+					"rp_id": {"type": "string", "description": "Relying party ID the passkey belongs to"}
 				},
-				"required": ["id", "name", "created_at", "last_used_at"],
+				"required": ["id", "name", "created_at", "last_used_at", "rp_id"],
 				"additionalProperties": false
 			},
 			"VoiceServerAdminResponse": {
@@ -25,6 +25,8 @@ pub struct InstanceConfigResponse {
    #[serde(default)]
    pub push_service_delivery: PushServiceDeliveryConfigResponse,
    #[serde(default)]
+    pub domain_migration: DomainMigrationConfigResponse,
+    #[serde(default)]
    pub experiment_delivery: ExperimentDeliveryConfigResponse,
 }

@@ -450,6 +452,7 @@ impl VoiceE2eeScope {

 pub const EXPERIMENT_MAX_TARGETED_USERS: usize = 1_000;
 pub const PUSH_SERVICE_DELIVERY_DEFAULT_SALT: &str = "push-service-delivery-v1";
+pub const DOMAIN_MIGRATION_DEFAULT_SALT: &str = "domain-migration-v1";
 pub const VOICE_NS_MAX_GUILD_OVERRIDES: usize = 200;

 impl NoiseSuppressionBackend {
@@ -549,6 +552,9 @@ pub struct PushServiceDeliveryConfigResponse {
    pub rollout_salt: String,
    pub included_user_ids: Vec<String>,
    pub excluded_user_ids: Vec<String>,
+    pub relay_consent_accepted: bool,
+    pub relay_consent_accepted_at: Option<String>,
+    pub relay_consent_accepted_by: Option<String>,
 }

 impl Default for PushServiceDeliveryConfigResponse {
@@ -560,6 +566,9 @@ impl Default for PushServiceDeliveryConfigResponse {
            rollout_salt: PUSH_SERVICE_DELIVERY_DEFAULT_SALT.to_owned(),
            included_user_ids: Vec::new(),
            excluded_user_ids: Vec::new(),
+            relay_consent_accepted: false,
+            relay_consent_accepted_at: None,
+            relay_consent_accepted_by: None,
        }
    }
 }
@@ -576,6 +585,54 @@ pub struct PushServiceDeliveryConfigUpdateRequest {
    pub included_user_ids: Option<Vec<String>>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub excluded_user_ids: Option<Vec<String>>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub relay_consent_accepted: Option<bool>,
+}
+
+#[derive(Clone, Debug, Deserialize, Serialize)]
+#[serde(default)]
+pub struct DomainMigrationConfigResponse {
+    pub enabled: bool,
+    pub config_version: u64,
+    pub rollout_basis_points: u32,
+    pub rollout_salt: String,
+    pub included_user_ids: Vec<String>,
+    pub excluded_user_ids: Vec<String>,
+    pub anonymous_rollout_basis_points: u32,
+    pub standalone_forwarding: bool,
+}
+
+impl Default for DomainMigrationConfigResponse {
+    fn default() -> Self {
+        Self {
+            enabled: false,
+            config_version: 0,
+            rollout_basis_points: 0,
+            rollout_salt: DOMAIN_MIGRATION_DEFAULT_SALT.to_owned(),
+            included_user_ids: Vec::new(),
+            excluded_user_ids: Vec::new(),
+            anonymous_rollout_basis_points: 0,
+            standalone_forwarding: false,
+        }
+    }
+}
+
+#[derive(Clone, Debug, Default, Serialize)]
+pub struct DomainMigrationConfigUpdateRequest {
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub enabled: Option<bool>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub rollout_basis_points: Option<u32>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub rollout_salt: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub included_user_ids: Option<Vec<String>>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub excluded_user_ids: Option<Vec<String>>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub anonymous_rollout_basis_points: Option<u32>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub standalone_forwarding: Option<bool>,
 }

 #[derive(Clone, Debug, Deserialize, Serialize)]
@@ -696,6 +753,8 @@ pub struct InstanceConfigUpdateRequest {
    #[serde(skip_serializing_if = "Option::is_none")]
    pub push_service_delivery: Option<PushServiceDeliveryConfigUpdateRequest>,
    #[serde(skip_serializing_if = "Option::is_none")]
+    pub domain_migration: Option<DomainMigrationConfigUpdateRequest>,
+    #[serde(skip_serializing_if = "Option::is_none")]
    pub experiment_delivery: Option<ExperimentDeliveryConfigUpdateRequest>,
 }

@@ -1033,18 +1092,30 @@ mod tests {
                .expect("admin schema");
        let noise = serde_json::from_value::<VoiceNoiseSuppressionConfigResponse>(json!({}))
            .expect("default noise config");
+        let domain_migration = serde_json::from_value::<DomainMigrationConfigResponse>(json!({}))
+            .expect("default domain migration config");
        let delivery = serde_json::from_value::<ExperimentDeliveryConfigResponse>(json!({}))
            .expect("default delivery config");
        let noise = serde_json::to_value(noise).expect("serializable noise config");
+        let domain_migration =
+            serde_json::to_value(domain_migration).expect("serializable domain migration config");
        let delivery = serde_json::to_value(delivery).expect("serializable delivery config");
        let generated_noise: generated_types::VoiceNoiseSuppressionConfigResponse =
            serde_json::from_value(noise.clone()).expect("generated noise config contract");
+        let generated_domain_migration: generated_types::DomainMigrationConfigResponse =
+            serde_json::from_value(domain_migration.clone())
+                .expect("generated domain migration config contract");
        let generated_delivery: generated_types::ExperimentDeliveryConfigResponse =
            serde_json::from_value(delivery.clone()).expect("generated delivery config contract");
        assert_eq!(
            serde_json::to_value(generated_noise).expect("serializable generated noise config"),
            noise
        );
+        assert_eq!(
+            serde_json::to_value(generated_domain_migration)
+                .expect("serializable generated domain migration config"),
+            domain_migration
+        );
        assert_eq!(
            serde_json::to_value(generated_delivery)
                .expect("serializable generated delivery config"),
@@ -1052,6 +1123,7 @@ mod tests {
        );
        for (name, value) in [
            ("VoiceNoiseSuppressionConfigResponse", noise),
+            ("DomainMigrationConfigResponse", domain_migration),
            ("ExperimentDeliveryConfigResponse", delivery),
        ] {
            for (field, value) in value.as_object().expect("config object") {
@@ -1087,4 +1159,27 @@ mod tests {
            json!({})
        );
    }
+
+    #[test]
+    fn domain_migration_update_preserves_empty_lists_and_omitted_fields() {
+        let update = DomainMigrationConfigUpdateRequest {
+            included_user_ids: Some(Vec::new()),
+            excluded_user_ids: Some(Vec::new()),
+            ..Default::default()
+        };
+        let value = serde_json::to_value(update).expect("serializable update");
+        serde_json::from_value::<generated_types::DomainMigrationConfigUpdateRequest>(
+            value.clone(),
+        )
+        .expect("generated update contract");
+        assert_eq!(
+            value,
+            json!({"included_user_ids": [], "excluded_user_ids": []})
+        );
+        assert_eq!(
+            serde_json::to_value(DomainMigrationConfigUpdateRequest::default())
+                .expect("serializable update"),
+            json!({})
+        );
+    }
 }
@@ -7,20 +7,21 @@ use crate::{
            AppBrandingConfigUpdateRequest, AppLegalConfigUpdateRequest,
            AppPublicConfigUpdateRequest, AppRegistrationConfigUpdateRequest,
            AppSetupConfigUpdateRequest, CreateRegistrationUrlRequest,
-            DeferredPhoneGateUpdateRequest, EXPERIMENT_MAX_TARGETED_USERS,
-            ExperimentDeliveryConfigUpdateRequest, GatewayRolloutConfigUpdateRequest,
-            GatewayRolloutMode, InstanceAttachmentDecayUpdateRequest,
-            InstanceBlueskyIntegrationUpdateRequest, InstanceBlueskyKeyIntegrationUpdateRequest,
-            InstanceCaptchaIntegrationUpdateRequest, InstanceConfigUpdateRequest,
-            InstanceEmailIntegrationUpdateRequest, InstanceEmailSmtpIntegrationUpdateRequest,
-            InstanceEmailSmtpTestRequest, InstanceGifIntegrationUpdateRequest,
-            InstanceIntegrationsUpdateRequest, InstanceMediaUpdateRequest,
-            InstancePolicyUpdateRequest, InstanceRegistrationConfigUpdateRequest,
-            InstanceServicesUpdateRequest, InstanceYoutubeIntegrationUpdateRequest,
-            LimitConfigUpdateRequest, LimitRule, LimitRuleFilters, NoiseSuppressionBackend,
-            PremiumMode, PushServiceDeliveryConfigUpdateRequest, RegistrationMode,
-            SsoConfigUpdateRequest, VOICE_NS_MAX_GUILD_OVERRIDES, VoiceE2eeScope,
-            VoiceNoiseSuppressionConfigUpdateRequest, VoiceNoiseSuppressionGuildOverride,
+            DeferredPhoneGateUpdateRequest, DomainMigrationConfigUpdateRequest,
+            EXPERIMENT_MAX_TARGETED_USERS, ExperimentDeliveryConfigUpdateRequest,
+            GatewayRolloutConfigUpdateRequest, GatewayRolloutMode,
+            InstanceAttachmentDecayUpdateRequest, InstanceBlueskyIntegrationUpdateRequest,
+            InstanceBlueskyKeyIntegrationUpdateRequest, InstanceCaptchaIntegrationUpdateRequest,
+            InstanceConfigUpdateRequest, InstanceEmailIntegrationUpdateRequest,
+            InstanceEmailSmtpIntegrationUpdateRequest, InstanceEmailSmtpTestRequest,
+            InstanceGifIntegrationUpdateRequest, InstanceIntegrationsUpdateRequest,
+            InstanceMediaUpdateRequest, InstancePolicyUpdateRequest,
+            InstanceRegistrationConfigUpdateRequest, InstanceServicesUpdateRequest,
+            InstanceYoutubeIntegrationUpdateRequest, LimitConfigUpdateRequest, LimitRule,
+            LimitRuleFilters, NoiseSuppressionBackend, PremiumMode,
+            PushServiceDeliveryConfigUpdateRequest, RegistrationMode, SsoConfigUpdateRequest,
+            VOICE_NS_MAX_GUILD_OVERRIDES, VoiceE2eeScope, VoiceNoiseSuppressionConfigUpdateRequest,
+            VoiceNoiseSuppressionGuildOverride,
        },
    },
    config::AdminConfig,
@@ -211,6 +212,10 @@ pub async fn instance_config_post(
            Ok(update) => instance_config_result(client.update_instance_config(&update).await),
            Err(message) => FlashData::error(message),
        },
+        "update_domain_migration" => match build_domain_migration_update(&form) {
+            Ok(update) => instance_config_result(client.update_instance_config(&update).await),
+            Err(message) => FlashData::error(message),
+        },
        "update_experiment_delivery" => match build_experiment_delivery_update(&form) {
            Ok(update) => instance_config_result(client.update_instance_config(&update).await),
            Err(message) => FlashData::error(message),
@@ -496,7 +501,7 @@ fn parse_experiment_rollout_salt(
    Ok(Some(salt.to_owned()))
 }

-fn parse_push_service_delivery_rollout_salt(
+fn parse_ascii_experiment_rollout_salt(
    form: &MultiValueForm,
    key: &str,
 ) -> Result<Option<String>, String> {
@@ -661,7 +666,7 @@ fn build_push_service_delivery_update(
                0,
                EXPERIMENT_ROLLOUT_BASIS_POINTS_MAX,
            )?,
-            rollout_salt: parse_push_service_delivery_rollout_salt(
+            rollout_salt: parse_ascii_experiment_rollout_salt(
                form,
                "push_service_delivery_rollout_salt",
            )?,
@@ -675,6 +680,49 @@ fn build_push_service_delivery_update(
                    .unwrap_or_default(),
                "Excluded user IDs",
            )?),
+            relay_consent_accepted: Some(
+                form.bool_value("push_service_delivery_relay_consent_accepted"),
+            ),
+        }),
+        ..Default::default()
+    })
+}
+
+fn build_domain_migration_update(
+    form: &MultiValueForm,
+) -> Result<InstanceConfigUpdateRequest, String> {
+    Ok(InstanceConfigUpdateRequest {
+        domain_migration: Some(DomainMigrationConfigUpdateRequest {
+            enabled: Some(form.bool_value("domain_migration_enabled")),
+            rollout_basis_points: parse_form_number(
+                form,
+                "domain_migration_rollout_basis_points",
+                "Rollout basis points",
+                0,
+                EXPERIMENT_ROLLOUT_BASIS_POINTS_MAX,
+            )?,
+            rollout_salt: parse_ascii_experiment_rollout_salt(
+                form,
+                "domain_migration_rollout_salt",
+            )?,
+            included_user_ids: Some(parse_experiment_user_ids(
+                form.first("domain_migration_included_user_ids")
+                    .unwrap_or_default(),
+                "Included user IDs",
+            )?),
+            excluded_user_ids: Some(parse_experiment_user_ids(
+                form.first("domain_migration_excluded_user_ids")
+                    .unwrap_or_default(),
+                "Excluded user IDs",
+            )?),
+            anonymous_rollout_basis_points: parse_form_number(
+                form,
+                "domain_migration_anonymous_rollout_basis_points",
+                "Anonymous rollout basis points",
+                0,
+                EXPERIMENT_ROLLOUT_BASIS_POINTS_MAX,
+            )?,
+            standalone_forwarding: Some(form.bool_value("domain_migration_standalone_forwarding")),
        }),
        ..Default::default()
    })
@@ -1601,6 +1649,115 @@ mod tests {
        }
    }

+    #[test]
+    fn build_domain_migration_update_reads_the_rollout_fields() {
+        let form = MultiValueForm::parse(
+            b"domain_migration_enabled=true&domain_migration_rollout_basis_points=%20250%20&domain_migration_rollout_salt=%20domain-migration-v2%20&domain_migration_included_user_ids=1500000000000000001%0A1500000000000000002&domain_migration_excluded_user_ids=1500000000000000003%2C%201500000000000000004&domain_migration_anonymous_rollout_basis_points=%20100%20&domain_migration_standalone_forwarding=true",
+        );
+        let update = build_domain_migration_update(&form)
+            .expect("valid form")
+            .domain_migration
+            .expect("domain migration update");
+        assert_eq!(update.enabled, Some(true));
+        assert_eq!(update.rollout_basis_points, Some(250));
+        assert_eq!(update.rollout_salt, Some("domain-migration-v2".to_owned()));
+        assert_eq!(
+            update.included_user_ids,
+            Some(vec![
+                "1500000000000000001".to_owned(),
+                "1500000000000000002".to_owned()
+            ])
+        );
+        assert_eq!(
+            update.excluded_user_ids,
+            Some(vec![
+                "1500000000000000003".to_owned(),
+                "1500000000000000004".to_owned()
+            ])
+        );
+        assert_eq!(update.anonymous_rollout_basis_points, Some(100));
+        assert_eq!(update.standalone_forwarding, Some(true));
+    }
+
+    #[test]
+    fn build_domain_migration_update_leaves_the_feature_inert_when_nothing_is_submitted() {
+        let form = MultiValueForm::parse(b"_csrf=token");
+        let request = build_domain_migration_update(&form).expect("valid form");
+        assert_eq!(
+            serde_json::to_value(request).expect("serializable update"),
+            serde_json::json!({"domain_migration": {
+                "enabled": false,
+                "included_user_ids": [],
+                "excluded_user_ids": [],
+                "standalone_forwarding": false,
+            }})
+        );
+    }
+
+    #[test]
+    fn build_domain_migration_update_rejects_invalid_rollout_fields() {
+        for (form, message) in [
+            (
+                "domain_migration_rollout_basis_points=10001",
+                "Rollout basis points must be a whole number between 0 and 10000",
+            ),
+            (
+                "domain_migration_anonymous_rollout_basis_points=10001",
+                "Anonymous rollout basis points must be a whole number between 0 and 10000",
+            ),
+            (
+                "domain_migration_anonymous_rollout_basis_points=abc",
+                "Anonymous rollout basis points must be a whole number between 0 and 10000",
+            ),
+            (
+                "domain_migration_rollout_salt=%20%20",
+                "Rollout salt must be between 1 and 64 characters",
+            ),
+            (
+                "domain_migration_rollout_salt=caf%C3%A9",
+                "Rollout salt must use printable ASCII",
+            ),
+            (
+                "domain_migration_included_user_ids=123%2Cinvalid",
+                "Included user IDs entry 2 must contain 1 to 20 decimal digits",
+            ),
+            (
+                "domain_migration_excluded_user_ids=123%2Cinvalid",
+                "Excluded user IDs entry 2 must contain 1 to 20 decimal digits",
+            ),
+        ] {
+            let form = MultiValueForm::parse(form.as_bytes());
+            assert_eq!(
+                build_domain_migration_update(&form).expect_err("invalid rollout field"),
+                message
+            );
+        }
+    }
+
+    #[test]
+    fn build_push_service_delivery_update_reads_the_relay_consent_checkbox() {
+        let unchecked = MultiValueForm::parse(b"_csrf=token");
+        assert_eq!(
+            build_push_service_delivery_update(&unchecked)
+                .expect("valid form")
+                .push_service_delivery
+                .expect("push service delivery update")
+                .relay_consent_accepted,
+            Some(false)
+        );
+
+        let checked =
+            MultiValueForm::parse(b"_csrf=token&push_service_delivery_relay_consent_accepted=true");
+        assert_eq!(
+            build_push_service_delivery_update(&checked)
+                .expect("valid form")
+                .push_service_delivery
+                .expect("push service delivery update")
+                .relay_consent_accepted,
+            Some(true)
+        );
+    }
+
    #[test]
    fn build_experiment_delivery_update_leaves_both_fields_unchanged_when_absent() {
        let form = MultiValueForm::parse(b"_csrf=token");
@@ -2,7 +2,8 @@

 use crate::{
    api::types::{
-        AppPublicConfigResponse, EXPERIMENT_MAX_TARGETED_USERS, ExperimentDeliveryConfigResponse,
+        AppPublicConfigResponse, DOMAIN_MIGRATION_DEFAULT_SALT, DomainMigrationConfigResponse,
+        EXPERIMENT_MAX_TARGETED_USERS, ExperimentDeliveryConfigResponse,
        GatewayRolloutConfigResponse, InstanceConfigResponse, InstanceIntegrationsResponse,
        InstanceMediaResponse, InstancePolicyResponse, InstanceRegistrationResponse,
        LimitConfigResponse, NoiseSuppressionBackend, PUSH_SERVICE_DELIVERY_DEFAULT_SALT,
@@ -149,6 +150,7 @@ pub fn instance_config_page(
                        (gateway_rollout_section(base, csrf_token, &instance_config.gateway_rollout))
                        (voice_noise_suppression_section(base, csrf_token, &instance_config.voice_noise_suppression))
                        (push_service_delivery_section(base, csrf_token, &instance_config.push_service_delivery))
+                        (domain_migration_section(base, csrf_token, &instance_config.domain_migration))
                        (experiment_delivery_section(base, csrf_token, &instance_config.experiment_delivery))
                        @if let Some(limit_config) = limit_config {
                            (limit_config_section(base, limit_config))
@@ -1189,6 +1191,14 @@ fn push_service_delivery_section(
    };
    let included_user_ids = push_service_delivery.included_user_ids.join("\n");
    let excluded_user_ids = push_service_delivery.excluded_user_ids.join("\n");
+    let relay_consent_stamp = match (
+        push_service_delivery.relay_consent_accepted_at.as_deref(),
+        push_service_delivery.relay_consent_accepted_by.as_deref(),
+    ) {
+        (Some(at), Some(by)) => Some(format!("Accepted {at} by user {by}")),
+        (Some(at), None) => Some(format!("Accepted {at}")),
+        _ => None,
+    };
    section_card_with_description(
        "Push Service Delivery",
        "Routes push notification delivery for the selected accounts through the push service. \
@@ -1217,6 +1227,28 @@ fn push_service_delivery_section(
                         effect at all."
                    }

+                    h3 class="text-sm font-semibold text-neutral-900" { "Managed relay consent" }
+                    (checkbox(
+                        "push_service_delivery_relay_consent_accepted",
+                        "true",
+                        "Accept the push relay supplemental privacy notice",
+                        push_service_delivery.relay_consent_accepted,
+                        true,
+                    ))
+                    p class="text-xs text-neutral-500" {
+                        "Required only for the official mobile apps, whose notifications travel \
+                         through Fluxer's relay to Apple and Google. Until this is accepted those \
+                         notifications are dropped. Self-hosted UnifiedPush and ntfy endpoints \
+                         never reach the relay and are unaffected. "
+                        a href="https://fluxer.com/push-relay" target="_blank" rel="noreferrer"
+                            class="text-neutral-900 underline decoration-neutral-300 hover:text-neutral-600 hover:decoration-neutral-500" {
+                            "Read the notice"
+                        }
+                    }
+                    @if let Some(stamp) = relay_consent_stamp {
+                        p class="text-xs text-neutral-500" { (stamp) }
+                    }
+
                    h3 class="text-sm font-semibold text-neutral-900" { "Rollout" }
                    (number_field(
                        "push_service_delivery_rollout_basis_points",
@@ -1286,6 +1318,139 @@ fn push_service_delivery_section(
    )
 }

+fn domain_migration_section(
+    base: &str,
+    csrf_token: &str,
+    domain_migration: &DomainMigrationConfigResponse,
+) -> Markup {
+    let status = if domain_migration.enabled {
+        ("Live", BadgeVariant::Success)
+    } else {
+        ("Inert", BadgeVariant::Default)
+    };
+    let included_user_ids = domain_migration.included_user_ids.join("\n");
+    let excluded_user_ids = domain_migration.excluded_user_ids.join("\n");
+    section_card_with_description(
+        "Domain Migration",
+        "Moves web clients of the official instance from the legacy web app origin to the new \
+         one. Selected accounts copy their local data across and continue on the new origin. \
+         Clients of other instances read this configuration and ignore it.",
+        html! {
+            form method="post" action={(base) "/instance-config?action=update_domain_migration"} {
+                (csrf_input(csrf_token))
+                div class="space-y-6" {
+                    div class="flex flex-wrap items-center gap-2" {
+                        h3 class="text-sm font-semibold text-neutral-900" { "Master switch" }
+                        (badge(status.0, status.1))
+                        span class="text-xs text-neutral-500" {
+                            "Config version " (domain_migration.config_version)
+                        }
+                    }
+                    (checkbox(
+                        "domain_migration_enabled",
+                        "true",
+                        "Move selected web clients to the new origin",
+                        domain_migration.enabled,
+                        true,
+                    ))
+                    p class="text-xs text-neutral-500" {
+                        "Off is the safe state and the kill switch. With this unchecked no client \
+                         starts a migration and clients that already migrated stop forwarding the \
+                         legacy origin, so the rollout and targeting fields below have no effect at all."
+                    }
+
+                    h3 class="text-sm font-semibold text-neutral-900" { "Installed apps" }
+                    (checkbox(
+                        "domain_migration_standalone_forwarding",
+                        "true",
+                        "Forward installed desktop web apps to the new origin",
+                        domain_migration.standalone_forwarding,
+                        true,
+                    ))
+                    p class="text-xs text-neutral-500" {
+                        "Leave this off until the manifest scope extension and the association file \
+                         are live and verified. While it is off, installed Chromium desktop apps copy \
+                         their data across but stay on the legacy origin and offer to install the new \
+                         app. Installed mobile and Safari apps never forward either way."
+                    }
+
+                    h3 class="text-sm font-semibold text-neutral-900" { "Rollout" }
+                    (number_field(
+                        "domain_migration_rollout_basis_points",
+                        "Rollout (basis points)",
+                        &domain_migration.rollout_basis_points.to_string(),
+                        Some(0), Some(10000), "1",
+                        Some("Share of logged-in users bucketed into the migration, in basis points: 0 is nobody, 100 is 1%, 10000 is everybody."),
+                    ))
+                    (number_field(
+                        "domain_migration_anonymous_rollout_basis_points",
+                        "Anonymous rollout (basis points)",
+                        &domain_migration.anonymous_rollout_basis_points.to_string(),
+                        Some(0), Some(10000), "1",
+                        Some("Share of logged-out devices sent to the new origin, in basis points. Each device is bucketed on its own random ID."),
+                    ))
+                    div class="flex flex-col gap-2" {
+                        (text_input(
+                            "domain_migration_rollout_salt",
+                            "Rollout Salt",
+                            &domain_migration.rollout_salt,
+                            DOMAIN_MIGRATION_DEFAULT_SALT,
+                        ))
+                        p class="text-xs text-neutral-500" {
+                            "Seeds the bucketing hash for users and devices. Changing it reshuffles \
+                             which users and devices fall inside the percentages above. Leave it \
+                             alone to keep the current cohort stable."
+                        }
+                    }
+                    div class="flex flex-col gap-2" {
+                        (textarea_input(
+                            "domain_migration_included_user_ids",
+                            "Always-on User IDs",
+                            "1500000000000000001\n1500000000000000002",
+                            &included_user_ids,
+                            4,
+                            false,
+                        ))
+                        (entry_count_hint(
+                            domain_migration.included_user_ids.len(),
+                            EXPERIMENT_MAX_TARGETED_USERS,
+                        ))
+                        p class="text-xs text-neutral-500" {
+                            "One snowflake per line, or comma separated. These users are targeted \
+                             regardless of the percentage above. IDs must contain 1 to 20 decimal \
+                             digits. Invalid entries prevent the save. Blank entries and duplicate \
+                             IDs are ignored."
+                        }
+                    }
+                    div class="flex flex-col gap-2" {
+                        (textarea_input(
+                            "domain_migration_excluded_user_ids",
+                            "Never-on User IDs",
+                            "1500000000000000003\n1500000000000000004",
+                            &excluded_user_ids,
+                            4,
+                            false,
+                        ))
+                        (entry_count_hint(
+                            domain_migration.excluded_user_ids.len(),
+                            EXPERIMENT_MAX_TARGETED_USERS,
+                        ))
+                        p class="text-xs text-neutral-500" {
+                            "Same format. Exclusion wins over both the always-on list and the \
+                             percentage. It stops new migrations only. A user who already moved \
+                             stays on the new origin."
+                        }
+                    }
+
+                    (form_actions(html! {
+                        (submit_button("Save Domain Migration Configuration"))
+                    }))
+                }
+            }
+        },
+    )
+}
+
 fn experiment_delivery_section(
    base: &str,
    csrf_token: &str,
@@ -1929,6 +2094,51 @@ mod tests {
        assert!(!markup.contains("at the cap"));
    }

+    #[test]
+    fn domain_migration_section_shows_both_rollouts_and_list_counts() {
+        let domain_migration = DomainMigrationConfigResponse {
+            anonymous_rollout_basis_points: 250,
+            included_user_ids: vec!["1500000000000000001".to_owned()],
+            excluded_user_ids: vec![
+                "1500000000000000002".to_owned(),
+                "1500000000000000003".to_owned(),
+            ],
+            ..DomainMigrationConfigResponse::default()
+        };
+        let markup = domain_migration_section("/admin", "csrf", &domain_migration).into_string();
+        assert!(markup.contains("action=update_domain_migration"));
+        assert!(markup.contains("domain_migration_enabled"));
+        assert!(markup.contains("name=\"domain_migration_anonymous_rollout_basis_points\""));
+        assert!(markup.contains("value=\"250\""));
+        assert!(markup.contains("name=\"domain_migration_standalone_forwarding\""));
+        assert!(markup.contains("1 of 1000 stored"));
+        assert!(markup.contains("2 of 1000 stored"));
+        assert!(!markup.contains("at the cap"));
+    }
+
+    #[test]
+    fn push_service_delivery_section_shows_the_relay_consent_toggle() {
+        let accepted = PushServiceDeliveryConfigResponse {
+            relay_consent_accepted: true,
+            relay_consent_accepted_at: Some("2026-09-27T10:11:12.000Z".to_owned()),
+            relay_consent_accepted_by: Some("1130650140672000000".to_owned()),
+            ..PushServiceDeliveryConfigResponse::default()
+        };
+        let markup = push_service_delivery_section("/admin", "csrf", &accepted).into_string();
+        assert!(markup.contains("name=\"push_service_delivery_relay_consent_accepted\""));
+        assert!(markup.contains("https://fluxer.com/push-relay"));
+        assert!(markup.contains("Accepted 2026-09-27T10:11:12.000Z by user 1130650140672000000"));
+
+        let unaccepted = push_service_delivery_section(
+            "/admin",
+            "csrf",
+            &PushServiceDeliveryConfigResponse::default(),
+        )
+        .into_string();
+        assert!(unaccepted.contains("name=\"push_service_delivery_relay_consent_accepted\""));
+        assert!(!unaccepted.contains("Accepted "));
+    }
+
    #[test]
    fn voice_noise_suppression_section_flags_a_list_at_its_cap() {
        let voice_noise_suppression = VoiceNoiseSuppressionConfigResponse {
@@ -415,7 +415,21 @@ fn deserialize_instance_config_response_with_unknown_keys() {
            "rollout_basis_points": 5000,
            "rollout_salt": "push-service-delivery-v1",
            "included_user_ids": ["1500000000000000002"],
-            "excluded_user_ids": []
+            "excluded_user_ids": [],
+            "relay_consent_accepted": true,
+            "relay_consent_accepted_at": "2026-09-27T10:11:12.000Z",
+            "relay_consent_accepted_by": "1130650140672000000"
+        },
+        "domain_migration": {
+            "enabled": true,
+            "config_version": 2,
+            "rollout_basis_points": 2500,
+            "rollout_salt": "domain-migration-v1",
+            "included_user_ids": ["1500000000000000001"],
+            "excluded_user_ids": [],
+            "future_migration_knob": 9,
+            "anonymous_rollout_basis_points": 100,
+            "standalone_forwarding": true
        },
        "experiment_delivery": {"poll_interval_seconds": 300, "poll_jitter_percent": 15},
        "registration": {
@@ -546,6 +560,14 @@ fn deserialize_instance_config_response_with_unknown_keys() {
    assert_eq!(resp.voice_noise_suppression.rollout_basis_points, 10000);
    assert_eq!(*resp.voice_noise_suppression.rollout_salt, "voice-ns-v1");
    assert_eq!(resp.voice_noise_suppression.enabled_backends.len(), 3);
+    assert!(resp.domain_migration.enabled);
+    assert_eq!(resp.domain_migration.config_version, 2);
+    assert_eq!(resp.domain_migration.rollout_basis_points, 2500);
+    assert_eq!(*resp.domain_migration.rollout_salt, "domain-migration-v1");
+    assert_eq!(resp.domain_migration.included_user_ids.len(), 1);
+    assert_eq!(resp.domain_migration.anonymous_rollout_basis_points, 100);
+    assert!(resp.domain_migration.standalone_forwarding);
+    assert!(resp.push_service_delivery.relay_consent_accepted);
    assert_eq!(resp.experiment_delivery.poll_interval_seconds, 300);
    assert!(resp.policy.single_community_guild_id.is_none());
    assert_eq!(resp.policy.services.gif_enabled, Some(true));
@@ -556,6 +578,7 @@ fn deserialize_instance_config_response_with_unknown_keys() {
        .replace("\"future_rollout_knob\": 3,", "")
        .replace("\"future_presentation_knob\": \"verbose\",", "")
        .replace("\"future_knob\": 7,", "")
+        .replace("\"future_migration_knob\": 9,", "")
        .replace("\"future_object_knob\": {\"nested\": true},", "")
        .replace("\"future_list_knob\": [\"a\", \"b\"],", "")
        .replace(
@@ -577,6 +600,71 @@ fn deserialize_instance_config_response_with_unknown_keys() {
    );
 }

+#[test]
+fn deserialize_push_service_delivery_relay_consent() {
+    let accepted: types::PushServiceDeliveryConfigResponse = serde_json::from_str(
+        r#"{
+        "enabled": true,
+        "config_version": 3,
+        "rollout_basis_points": 5000,
+        "rollout_salt": "push-service-delivery-v1",
+        "included_user_ids": [],
+        "excluded_user_ids": [],
+        "relay_consent_accepted": true,
+        "relay_consent_accepted_at": "2026-09-27T10:11:12.000Z",
+        "relay_consent_accepted_by": "1130650140672000000"
+    }"#,
+    )
+    .expect("an accepted relay consent must deserialize");
+
+    assert!(accepted.relay_consent_accepted);
+    assert_eq!(
+        accepted.relay_consent_accepted_at.as_deref(),
+        Some("2026-09-27T10:11:12.000Z")
+    );
+    assert_eq!(
+        accepted.relay_consent_accepted_by.as_deref(),
+        Some("1130650140672000000")
+    );
+
+    let legacy: types::PushServiceDeliveryConfigResponse = serde_json::from_str(
+        r#"{
+        "enabled": true,
+        "config_version": 3,
+        "rollout_basis_points": 5000,
+        "rollout_salt": "push-service-delivery-v1",
+        "included_user_ids": [],
+        "excluded_user_ids": []
+    }"#,
+    )
+    .expect("a response written before relay consent must still deserialize");
+
+    assert!(!legacy.relay_consent_accepted);
+    assert!(legacy.relay_consent_accepted_at.is_none());
+    assert!(legacy.relay_consent_accepted_by.is_none());
+}
+
+#[test]
+fn serialize_push_service_delivery_update_omits_an_unset_relay_consent() {
+    let without = types::PushServiceDeliveryConfigUpdateRequest {
+        enabled: Some(true),
+        ..Default::default()
+    };
+    assert_eq!(
+        serde_json::to_value(&without).unwrap(),
+        serde_json::json!({"enabled": true})
+    );
+
+    let with = types::PushServiceDeliveryConfigUpdateRequest {
+        relay_consent_accepted: Some(true),
+        ..Default::default()
+    };
+    assert_eq!(
+        serde_json::to_value(&with).unwrap(),
+        serde_json::json!({"relay_consent_accepted": true})
+    );
+}
+
 #[test]
 fn deserialize_search_reports_response() {
    let json = r#"{
@@ -851,7 +939,8 @@ fn deserialize_webauthn_credentials_response() {
            "id": "credential-a",
            "name": "YubiKey",
            "created_at": "2026-05-26T12:00:00.000Z",
-            "last_used_at": null
+            "last_used_at": null,
+            "rp_id": "fluxer.com"
        },
        {
            "id": "credential-b",
@@ -465,6 +465,7 @@ async fn mutating_admin_pages_render_usable_csrf_tokens() {
                "/instance-config?action=update_gateway_rollout",
                "/instance-config?action=update_sso",
                "/instance-config?action=update_voice_noise_suppression",
+                "/instance-config?action=update_domain_migration",
                "/instance-config?action=update_experiment_delivery",
            ][..],
        ),
@@ -1199,6 +1200,16 @@ fn instance_config() -> Value {
            "guild_overrides": [],
            "suppression_strength": 80
        },
+        "domain_migration": {
+            "enabled": false,
+            "config_version": 0,
+            "rollout_basis_points": 0,
+            "rollout_salt": "domain-migration-v1",
+            "included_user_ids": [],
+            "excluded_user_ids": [],
+            "anonymous_rollout_basis_points": 0,
+            "standalone_forwarding": false
+        },
        "experiment_delivery": {
            "poll_interval_seconds": 300,
            "poll_jitter_percent": 15
@@ -45,7 +45,7 @@ export async function createAPIApp(options: CreateAPIAppOptions): Promise<APIApp
 	configureMiddleware(routes, {
 		logger,
 		nodeEnv: config.nodeEnv,
-		corsOrigins: [config.endpoints.webApp, config.endpoints.marketing],
+		corsOrigins: [...config.endpoints.webAppOrigins, config.endpoints.marketing],
 		trustClientIpHeader: config.proxy.trust_client_ip_header,
 		clientIpHeaderName: config.proxy.client_ip_header,
 		maxInflightRequests: config.maxInflightRequests,
@@ -258,6 +258,7 @@ export function buildAPIConfigFromMaster(master: MasterConfig): APIConfig {
 			apiPublic: master.endpoints.api,
 			apiClient: master.endpoints.api_client,
 			webApp: master.endpoints.app,
+			webAppOrigins: [...new Set([new URL(master.endpoints.app).origin, ...master.services.api.app_origin_aliases])],
 			gateway: master.endpoints.gateway,
 			media: master.endpoints.media,
 			marketing: master.endpoints.marketing,
@@ -34,8 +34,13 @@ import {
 	PendingRegistrationActionRequest,
 	RegistrationUrlIdParam,
 } from '@fluxer/schema/src/domains/admin/AdminSchemas';
+import {DomainMigrationConfigSchema} from '@fluxer/schema/src/domains/admin/DomainMigrationSchemas';
 import {GatewayRolloutConfigSchema} from '@fluxer/schema/src/domains/admin/GatewayRolloutSchemas';
-import {PushServiceDeliveryConfigSchema} from '@fluxer/schema/src/domains/admin/PushServiceDeliverySchemas';
+import {
+	type PushServiceDeliveryConfig,
+	PushServiceDeliveryConfigSchema,
+	type PushServiceDeliveryConfigUpdateRequest,
+} from '@fluxer/schema/src/domains/admin/PushServiceDeliverySchemas';
 import {VoiceNoiseSuppressionConfigSchema} from '@fluxer/schema/src/domains/admin/VoiceNoiseSuppressionSchemas';
 import {UserIdParam} from '@fluxer/schema/src/domains/common/CommonParamSchemas';
 import {ExperimentDeliveryConfigSchema} from '@fluxer/schema/src/domains/experiment/ExperimentSchemas';
@@ -65,6 +70,7 @@ async function buildInstanceConfigResponse(): Promise<InstanceConfigResponse> {
 		gatewayRollout,
 		voiceNoiseSuppression,
 		pushServiceDelivery,
+		domainMigration,
 		experimentDelivery,
 		registrationConfig,
 		registrationUrls,
@@ -74,6 +80,7 @@ async function buildInstanceConfigResponse(): Promise<InstanceConfigResponse> {
 		instanceConfigRepository.getGatewayRolloutConfig(),
 		instanceConfigRepository.getVoiceNoiseSuppressionConfig(),
 		instanceConfigRepository.getPushServiceDeliveryConfig(),
+		instanceConfigRepository.getDomainMigrationConfig(),
 		instanceConfigRepository.getExperimentDeliveryConfig(),
 		instanceConfigRepository.getRegistrationConfig(),
 		instanceConfigRepository.getRegistrationUrlsForAdmin(),
@@ -106,6 +113,7 @@ async function buildInstanceConfigResponse(): Promise<InstanceConfigResponse> {
 		gateway_rollout: gatewayRollout,
 		voice_noise_suppression: voiceNoiseSuppression,
 		push_service_delivery: pushServiceDelivery,
+		domain_migration: domainMigration,
 		experiment_delivery: experimentDelivery,
 		registration: {
 			...registrationConfig,
@@ -190,6 +198,20 @@ async function grantSetupCompleterAdminACL(ctx: Context<HonoEnv>): Promise<boole
 	return true;
 }

+function relayConsentStamp(
+	current: PushServiceDeliveryConfig,
+	patch: Partial<PushServiceDeliveryConfigUpdateRequest>,
+	adminUserId: string,
+): Partial<PushServiceDeliveryConfig> {
+	const accepted = patch.relay_consent_accepted;
+	if (accepted === undefined || accepted === current.relay_consent_accepted) {
+		return {};
+	}
+	return accepted
+		? {relay_consent_accepted_at: new Date().toISOString(), relay_consent_accepted_by: adminUserId}
+		: {relay_consent_accepted_at: null, relay_consent_accepted_by: null};
+}
+
 function listSuppliedSections(data: InstanceConfigUpdateRequest): string | undefined {
 	const sections = Object.entries(data)
 		.filter(([, value]) => value != null)
@@ -272,14 +294,28 @@ export function InstanceConfigAdminController(app: HonoApp) {
 			if (data.push_service_delivery) {
 				const patch = omitUndefinedFields(data.push_service_delivery);
 				if (Object.keys(patch).length > 0) {
+					const adminUserId = ctx.get('adminUserId').toString();
 					const landed = await instanceConfigRepository.updatePushServiceDeliveryConfig((current) =>
 						PushServiceDeliveryConfigSchema.parse({
+							...current,
+							...patch,
+							...relayConsentStamp(current, patch, adminUserId),
+							config_version: current.config_version + 1,
+						}),
+					);
+					await getPushServiceDeliveryConfigPublisher().publish(landed);
+				}
+			}
+			if (data.domain_migration) {
+				const patch = omitUndefinedFields(data.domain_migration);
+				if (Object.keys(patch).length > 0) {
+					await instanceConfigRepository.updateDomainMigrationConfig((current) =>
+						DomainMigrationConfigSchema.parse({
 							...current,
 							...patch,
 							config_version: current.config_version + 1,
 						}),
 					);
-					await getPushServiceDeliveryConfigPublisher().publish(landed);
 				}
 			}
 			if (data.experiment_delivery) {
@@ -8,12 +8,14 @@ import * as AuthEmail from '@app/api/auth/AuthEmail';
 import * as AuthMfa from '@app/api/auth/AuthMfa';
 import * as AuthSession from '@app/api/auth/AuthSession';
 import * as AuthUtility from '@app/api/auth/AuthUtility';
+import {visibleWebAuthnCredentials} from '@app/api/auth/services/PasskeyRelyingParty';
 import {createPasswordResetToken, createUserID, type UserID} from '@app/api/BrandedTypes';
 import type {UserRow} from '@app/api/database/types/UserTypes';
 import {Logger} from '@app/api/Logger';
 import {getInstanceConfigRepository} from '@app/api/middleware/ServiceSingletons';
 import type {IRiskHistoryRepository} from '@app/api/risk/HistoricalOutcomeRepository';
 import type {HistoricalOutcomeCode} from '@app/api/risk/RiskHistoryTypes';
+import {mapWebAuthnCredentialToResponse} from '@app/api/user/UserMappers';
 import {resolveAssignedTraits} from '@app/api/user/UserTraits';
 import {getIpAddressReverse, getLocationLabelFromIp} from '@app/api/utils/IpUtils';
 import {resolveSessionClientInfo} from '@app/api/utils/SessionClientIdentity';
@@ -545,7 +547,7 @@ export class AdminUserSecurityService {
 		if (!user) {
 			throw new UnknownUserError();
 		}
-		const credentials = await userRepository.listWebAuthnCredentials(userId);
+		const credentials = visibleWebAuthnCredentials(await userRepository.listWebAuthnCredentials(userId));
 		await auditService.createAuditLog({
 			adminUserId,
 			targetType: 'user',
@@ -554,12 +556,9 @@ export class AdminUserSecurityService {
 			auditLogReason,
 			metadata: new Map([['credential_count', credentials.length.toString()]]),
 		});
-		return credentials.map((cred) => ({
-			id: cred.credentialId,
-			name: cred.name,
-			created_at: cred.createdAt.toISOString(),
-			last_used_at: cred.lastUsedAt?.toISOString() ?? null,
-		}));
+		return credentials.map((cred) =>
+			mapWebAuthnCredentialToResponse(cred, this.deps.apiContext.services.config.auth.passkeys.rpId),
+		);
 	}

 	async deleteWebAuthnCredential(
@@ -69,6 +69,20 @@ describe('instance config admin PATCH under concurrent writes', () => {
 		return logs.filter((log) => log.action === 'update_instance_config');
 	}

+	it('merges a standalone forwarding patch into the stored domain migration config', async () => {
+		const admin = await createAdmin();
+		await patchConfig(admin, {domain_migration: {enabled: true, rollout_basis_points: 250}}).execute();
+
+		const updated = await patchConfig(admin, {domain_migration: {standalone_forwarding: true}}).execute();
+
+		expect(updated.domain_migration).toMatchObject({
+			enabled: true,
+			rollout_basis_points: 250,
+			standalone_forwarding: true,
+			config_version: 2,
+		});
+	});
+
 	it('answers with a conflict and neither writes, publishes nor audits once every attempt has lost the race', async () => {
 		const publish = spyOnPushDeliveryPublishes();
 		const admin = await createAdmin();
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import type {TestAccount} from '@app/api/auth/tests/AuthTestUtils';
+import {createTestAccount, setUserACLs} from '@app/api/auth/tests/AuthTestUtils';
+import {PushServiceDeliveryConfigPublisher} from '@app/api/instance/PushServiceDeliveryConfigPublisher';
+import type {ApiTestHarness} from '@app/api/test/ApiTestHarness';
+import {createApiTestHarness} from '@app/api/test/ApiTestHarness';
+import {createBuilder} from '@app/api/test/TestRequestBuilder';
+import {AdminACLs} from '@fluxer/constants/src/AdminACLs';
+import type {InstanceConfigResponse} from '@fluxer/schema/src/domains/admin/AdminSchemas';
+import {afterAll, afterEach, beforeAll, beforeEach, describe, expect, it, vi} from 'vitest';
+
+describe('push relay supplemental notice consent', () => {
+	let harness: ApiTestHarness;
+
+	beforeAll(async () => {
+		harness = await createApiTestHarness();
+	});
+
+	beforeEach(async () => {
+		await harness.reset();
+		vi.spyOn(PushServiceDeliveryConfigPublisher.prototype, 'publish').mockResolvedValue(undefined);
+	});
+
+	afterEach(() => {
+		vi.restoreAllMocks();
+	});
+
+	afterAll(async () => {
+		await harness.shutdown();
+	});
+
+	const createAdmin = async (): Promise<TestAccount> =>
+		await setUserACLs(harness, await createTestAccount(harness), [
+			AdminACLs.AUTHENTICATE,
+			AdminACLs.INSTANCE_CONFIG_VIEW,
+			AdminACLs.INSTANCE_CONFIG_UPDATE,
+		]);
+
+	const patchConfig = (admin: TestAccount, body: Record<string, unknown>) =>
+		createBuilder<InstanceConfigResponse>(harness, admin.token).patch('/admin/instance/config').body(body);
+
+	const readConfig = (admin: TestAccount) =>
+		createBuilder<InstanceConfigResponse>(harness, admin.token).get('/admin/instance/config');
+
+	it('reads back as unaccepted before an operator agrees', async () => {
+		const admin = await createAdmin();
+
+		const config = await readConfig(admin).execute();
+
+		expect(config.push_service_delivery).toMatchObject({
+			relay_consent_accepted: false,
+			relay_consent_accepted_at: null,
+			relay_consent_accepted_by: null,
+		});
+	});
+
+	it('stamps the acting admin and the acceptance time when consent is given', async () => {
+		const admin = await createAdmin();
+
+		const updated = await patchConfig(admin, {push_service_delivery: {relay_consent_accepted: true}}).execute();
+
+		expect(updated.push_service_delivery.relay_consent_accepted).toBe(true);
+		expect(updated.push_service_delivery.relay_consent_accepted_by).toBe(admin.userId);
+		expect(Date.parse(updated.push_service_delivery.relay_consent_accepted_at ?? '')).not.toBeNaN();
+	});
+
+	it('keeps the first acceptance stamp when a later patch changes only the rollout', async () => {
+		const admin = await createAdmin();
+		const accepted = await patchConfig(admin, {push_service_delivery: {relay_consent_accepted: true}}).execute();
+
+		const rolledOut = await patchConfig(admin, {
+			push_service_delivery: {enabled: true, rollout_basis_points: 2500},
+		}).execute();
+
+		expect(rolledOut.push_service_delivery).toMatchObject({
+			enabled: true,
+			rollout_basis_points: 2500,
+			relay_consent_accepted: true,
+			relay_consent_accepted_at: accepted.push_service_delivery.relay_consent_accepted_at,
+			relay_consent_accepted_by: admin.userId,
+		});
+	});
+
+	it('keeps the stamp untouched when consent is re-sent unchanged', async () => {
+		const admin = await createAdmin();
+		const accepted = await patchConfig(admin, {push_service_delivery: {relay_consent_accepted: true}}).execute();
+
+		const resent = await patchConfig(admin, {push_service_delivery: {relay_consent_accepted: true}}).execute();
+
+		expect(resent.push_service_delivery.relay_consent_accepted_at).toBe(
+			accepted.push_service_delivery.relay_consent_accepted_at,
+		);
+	});
+
+	it('clears the stamp when an operator withdraws consent', async () => {
+		const admin = await createAdmin();
+		await patchConfig(admin, {push_service_delivery: {relay_consent_accepted: true}}).execute();
+
+		const withdrawn = await patchConfig(admin, {push_service_delivery: {relay_consent_accepted: false}}).execute();
+
+		expect(withdrawn.push_service_delivery).toMatchObject({
+			relay_consent_accepted: false,
+			relay_consent_accepted_at: null,
+			relay_consent_accepted_by: null,
+		});
+	});
+
+	it('ignores an acceptance stamp supplied by the caller', async () => {
+		const admin = await createAdmin();
+
+		const updated = await patchConfig(admin, {
+			push_service_delivery: {
+				relay_consent_accepted: true,
+				relay_consent_accepted_at: '2020-01-01T00:00:00.000Z',
+				relay_consent_accepted_by: '1500000000000000009',
+			},
+		}).execute();
+
+		expect(updated.push_service_delivery.relay_consent_accepted_at).not.toBe('2020-01-01T00:00:00.000Z');
+		expect(updated.push_service_delivery.relay_consent_accepted_by).toBe(admin.userId);
+	});
+
+	it('publishes the consent to the delivery services', async () => {
+		const admin = await createAdmin();
+		const publish = vi.mocked(PushServiceDeliveryConfigPublisher.prototype.publish);
+
+		await patchConfig(admin, {push_service_delivery: {relay_consent_accepted: true}}).execute();
+
+		expect(publish).toHaveBeenCalledWith(expect.objectContaining({relay_consent_accepted: true}));
+	});
+});
@@ -3,6 +3,8 @@
 import {registerAdminControllers} from '@app/api/admin/controllers/index';
 import {AttachmentController} from '@app/api/attachment/AttachmentController';
 import {AuthController} from '@app/api/auth/AuthController';
+import {OriginHandoffController} from '@app/api/auth/OriginHandoffController';
+import {PasskeyBridgeController} from '@app/api/auth/PasskeyBridgeController';
 import {BlueskyOAuthController} from '@app/api/bluesky/BlueskyOAuthController';
 import {Config} from '@app/api/Config';
 import {ChannelController} from '@app/api/channel/ChannelController';
@@ -46,6 +48,8 @@ export function registerControllers(routes: HonoApp, config: APIConfig): void {
 	GeolocationController(routes);
 	registerAdminControllers(routes);
 	AuthController(routes);
+	OriginHandoffController(routes);
+	PasskeyBridgeController(routes);
 	AttachmentController(routes);
 	ChannelController(routes);
 	ConnectionController(routes);
@@ -447,7 +447,7 @@ export function AuthController(app: HonoApp) {
 				'Retrieve WebAuthn authentication challenge and options for passwordless login with biometrics or security keys.',
 		}),
 		async (ctx) => {
-			return ctx.json(await ctx.get('authRequestService').getWebAuthnAuthenticationOptions());
+			return ctx.json(await ctx.get('authRequestService').getWebAuthnAuthenticationOptions(ctx.req.header('origin')));
 		},
 	);
 	app.post(
@@ -490,7 +490,9 @@ export function AuthController(app: HonoApp) {
 				'Retrieve WebAuthn challenge and options for multi-factor authentication. Requires the MFA ticket from initial login.',
 		}),
 		async (ctx) => {
-			return ctx.json(await ctx.get('authRequestService').getWebAuthnMfaOptions(ctx.req.valid('json')));
+			return ctx.json(
+				await ctx.get('authRequestService').getWebAuthnMfaOptions(ctx.req.valid('json'), ctx.req.header('origin')),
+			);
 		},
 	);
 	app.post(
@@ -602,6 +604,7 @@ export function AuthController(app: HonoApp) {
 				data: ctx.req.valid('json'),
 				clientIp,
 				authToken: ctx.get('authToken') ?? undefined,
+				approverOrigin: ctx.req.header('origin'),
 			});
 			return ctx.body(null, 204);
 		},
@@ -23,6 +23,7 @@ import type {InviteService} from '@app/api/invite/InviteService';
 import {Logger} from '@app/api/Logger';
 import {createRequestCache} from '@app/api/middleware/RequestCacheMiddleware';
 import {getInstanceConfigRepository} from '@app/api/middleware/ServiceSingletons';
+import type {AuthSession as AuthSessionModel} from '@app/api/models/AuthSession';
 import type {User} from '@app/api/models/User';
 import {lookupGeoip} from '@app/api/utils/IpUtils';
 import {createRateLimitError} from '@app/api/utils/RateLimitUtils';
@@ -353,7 +354,7 @@ export async function login(
 const MFA_TICKET_MAX_ATTEMPTS = 5;
 const MFA_USER_MAX_ATTEMPTS = 10;

-async function consumeMfaAttempt(
+export async function consumeMfaAttempt(
 	ctx: ApiContext,
 	{userId, ticket, field}: {userId: string; ticket: string; field: string},
 ): Promise<void> {
@@ -381,7 +382,7 @@ export async function loginMfaTotp(
 	ctx: ApiContext,
 	{code, ticket, request}: LoginMfaTotpParams,
 ): Promise<LoginTokenResult> {
-	const {users, cache, rateLimit} = ctx.services;
+	const {users, cache} = ctx.services;
 	const userId = await cache.get<string>(`mfa-ticket:${ticket}`);
 	if (!userId) {
 		throw InputValidationError.fromCode('ticket', ValidationErrorCodes.SESSION_TIMEOUT);
@@ -405,21 +406,36 @@ export async function loginMfaTotp(
 	if (!isValid) {
 		throw InputValidationError.fromCode('code', ValidationErrorCodes.INVALID_CODE);
 	}
+	const [token] = await completeMfaLogin(ctx, user, ticket, request);
+	return {user_id: user.id.toString(), token};
+}
+
+export async function createLoginSession(
+	ctx: ApiContext,
+	user: User,
+	request: Request,
+): Promise<[token: string, AuthSessionModel]> {
+	return AuthSession.createAuthSession(ctx, {user, origin: AuthSession.resolveSessionOrigin(ctx, request)});
+}
+
+export async function completeMfaLogin(
+	ctx: ApiContext,
+	user: User,
+	ticket: string,
+	request: Request,
+): Promise<[token: string, AuthSessionModel]> {
+	const {cache, rateLimit} = ctx.services;
 	await cache.delete(`mfa-ticket:${ticket}`);
 	await rateLimit.resetLimit(`mfa:ticket:${ticket}`);
 	await rateLimit.resetLimit(`mfa:user:${user.id}`);
-	const [token] = await AuthSession.createAuthSession(ctx, {
-		user,
-		origin: AuthSession.resolveSessionOrigin(ctx, request),
-	});
-	return {user_id: user.id.toString(), token};
+	return createLoginSession(ctx, user, request);
 }

 export async function loginMfaWebAuthn(
 	ctx: ApiContext,
 	{response, challenge, ticket, request}: LoginMfaWebAuthnParams,
 ): Promise<LoginTokenResult> {
-	const {users, cache, rateLimit} = ctx.services;
+	const {users, cache} = ctx.services;
 	const userId = await cache.get<string>(`mfa-ticket:${ticket}`);
 	if (!userId) {
 		throw InputValidationError.fromCode('ticket', ValidationErrorCodes.SESSION_TIMEOUT);
@@ -434,13 +450,7 @@ export async function loginMfaWebAuthn(
 	}
 	await consumeMfaAttempt(ctx, {userId: user.id.toString(), ticket, field: 'ticket'});
 	await AuthMfa.verifyWebAuthnAuthentication(ctx, user.id, response, challenge, 'mfa', ticket);
-	await cache.delete(`mfa-ticket:${ticket}`);
-	await rateLimit.resetLimit(`mfa:ticket:${ticket}`);
-	await rateLimit.resetLimit(`mfa:user:${user.id}`);
-	const [token] = await AuthSession.createAuthSession(ctx, {
-		user,
-		origin: AuthSession.resolveSessionOrigin(ctx, request),
-	});
+	const [token] = await completeMfaLogin(ctx, user, ticket, request);
 	return {user_id: user.id.toString(), token};
 }

@@ -3,13 +3,20 @@
 import {timingSafeEqual} from 'node:crypto';
 import type {ApiContext} from '@app/api/ApiContext';
 import * as AuthUtility from '@app/api/auth/AuthUtility';
+import {
+	type CredentialRpSelection,
+	effectiveRpId,
+	originRpId,
+	selectCredentialRp,
+	visibleWebAuthnCredentials,
+} from '@app/api/auth/services/PasskeyRelyingParty';
 import {deriveSudoMethods, userHasMfa, userHasSudoCapability} from '@app/api/auth/services/SudoMethods';
 import {createUserID, type UserID} from '@app/api/BrandedTypes';
 import {Logger} from '@app/api/Logger';
 import type {MfaBackupCode} from '@app/api/models/MfaBackupCode';
 import type {User} from '@app/api/models/User';
 import type {WebAuthnCredential} from '@app/api/models/WebAuthnCredential';
-import {mapUserToPrivateResponse} from '@app/api/user/UserMappers';
+import {mapUserToPrivateResponse, mapWebAuthnCredentialToResponse} from '@app/api/user/UserMappers';
 import {TotpGenerator} from '@app/api/utils/TotpGenerator';
 import {UserAuthenticatorTypes} from '@fluxer/constants/src/UserConstants';
 import {ValidationErrorCodes} from '@fluxer/constants/src/ValidationErrorCodes';
@@ -22,7 +29,12 @@ import {PasskeyAuthenticationFailedError} from '@fluxer/errors/src/domains/auth/
 import {UnknownWebAuthnCredentialError} from '@fluxer/errors/src/domains/auth/UnknownWebAuthnCredentialError';
 import {WebAuthnCredentialLimitReachedError} from '@fluxer/errors/src/domains/auth/WebAuthnCredentialLimitReachedError';
 import {InputValidationError} from '@fluxer/errors/src/domains/core/InputValidationError';
-import type {AuthenticationResponseJSON, RegistrationResponseJSON} from '@simplewebauthn/server';
+import type {
+	AuthenticationResponseJSON,
+	PublicKeyCredentialCreationOptionsJSON,
+	PublicKeyCredentialRequestOptionsJSON,
+	RegistrationResponseJSON,
+} from '@simplewebauthn/server';
 import {
 	generateAuthenticationOptions,
 	generateRegistrationOptions,
@@ -33,7 +45,41 @@ import {
 } from '@simplewebauthn/server';
 import {ms, seconds} from 'itty-time';

-type WebAuthnChallengeContext = 'registration' | 'discoverable' | 'mfa' | 'sudo';
+type WebAuthnChallengeContext = 'registration' | 'discoverable' | 'mfa' | 'sudo' | 'bridge' | 'migration_registration';
+
+interface WebAuthnChallengeEntry {
+	context: WebAuthnChallengeContext;
+	userId?: string;
+	ticket?: string;
+	rpId?: string;
+	credentialIds?: Array<string> | null;
+}
+
+interface WebAuthnChallengeScope {
+	rpId: string;
+	credentialIds: Array<string> | null;
+}
+
+interface WebAuthnAuthenticationOptionsParams {
+	selection: CredentialRpSelection | {rpId: string; credentials: null};
+	context: WebAuthnChallengeContext;
+	userId?: UserID;
+	ticket?: string;
+}
+
+interface WebAuthnRegistrationOptionsParams {
+	rpId: string;
+	context: WebAuthnChallengeContext;
+	excludeCredentials: Array<WebAuthnCredential>;
+}
+
+interface VerifiedWebAuthnRegistration {
+	credentialId: string;
+	publicKey: Buffer;
+	counter: bigint;
+	transports: Set<string> | null;
+	rpId: string;
+}

 interface SudoMfaVerificationParams {
 	userId: UserID;
@@ -122,37 +168,117 @@ export async function verifyMfaCode(ctx: ApiContext, params: VerifyMfaCodeParams
 	return false;
 }

-export async function generateWebAuthnRegistrationOptions(ctx: ApiContext, userId: UserID) {
+function toCredentialDescriptor(credential: WebAuthnCredential) {
+	return {
+		id: credential.credentialId,
+		transports: credential.transports
+			? (Array.from(credential.transports) as Array<'usb' | 'nfc' | 'ble' | 'internal' | 'cable' | 'hybrid'>)
+			: undefined,
+	};
+}
+
+export function storedRpId(ctx: ApiContext, rpId: string): string | null {
+	return rpId === ctx.services.config.auth.passkeys.rpId ? null : rpId;
+}
+
+export async function createWebAuthnRegistrationOptions(
+	ctx: ApiContext,
+	userId: UserID,
+	{rpId, context, excludeCredentials}: WebAuthnRegistrationOptionsParams,
+): Promise<PublicKeyCredentialCreationOptionsJSON> {
 	const {users, config} = ctx.services;
 	const user = await users.findUniqueAssert(userId);
-	const existingCredentials = await users.listWebAuthnCredentials(userId);
-	if (existingCredentials.length >= 10) {
-		throw new WebAuthnCredentialLimitReachedError();
-	}
 	const options = await generateRegistrationOptions({
 		rpName: config.auth.passkeys.rpName,
-		rpID: config.auth.passkeys.rpId,
+		rpID: rpId,
 		userID: new TextEncoder().encode(user.id.toString()),
 		userName: user.username!,
 		userDisplayName: user.username!,
 		attestationType: 'none',
 		supportedAlgorithmIDs: [-8, -7, -257],
-		excludeCredentials: existingCredentials.map((cred) => ({
-			id: cred.credentialId,
-			transports: cred.transports
-				? (Array.from(cred.transports) as Array<'usb' | 'nfc' | 'ble' | 'internal' | 'cable' | 'hybrid'>)
-				: undefined,
-		})),
+		excludeCredentials: excludeCredentials.map(toCredentialDescriptor),
 		authenticatorSelection: {
 			residentKey: 'preferred',
 			requireResidentKey: false,
 			userVerification: 'preferred',
 		},
 	});
-	await saveWebAuthnChallenge(ctx, options.challenge, {context: 'registration', userId});
+	await saveWebAuthnChallenge(ctx, options.challenge, {context, userId, rpId, credentialIds: null});
 	return options;
 }

+export async function generateWebAuthnRegistrationOptions(
+	ctx: ApiContext,
+	userId: UserID,
+	origin: string | null | undefined,
+): Promise<PublicKeyCredentialCreationOptionsJSON> {
+	const existingCredentials = await ctx.services.users.listWebAuthnCredentials(userId);
+	if (visibleWebAuthnCredentials(existingCredentials).length >= 10) {
+		throw new WebAuthnCredentialLimitReachedError();
+	}
+	return createWebAuthnRegistrationOptions(ctx, userId, {
+		rpId: originRpId(ctx, origin),
+		context: 'registration',
+		excludeCredentials: existingCredentials,
+	});
+}
+
+export async function verifyWebAuthnRegistrationResponse(
+	ctx: ApiContext,
+	userId: UserID,
+	response: RegistrationResponseJSON,
+	expectedChallenge: string,
+	context: WebAuthnChallengeContext,
+	expectedOrigin: Array<string> = ctx.services.config.auth.passkeys.allowedOrigins,
+): Promise<VerifiedWebAuthnRegistration> {
+	const {config} = ctx.services;
+	const {rpId} = await consumeWebAuthnChallenge(ctx, expectedChallenge, context, {userId});
+	const responseObj = response as {id?: string; response?: {transports?: Array<string>}};
+	const transports = responseObj.response?.transports ? new Set(responseObj.response.transports) : null;
+	if (config.dev.testModeEnabled) {
+		const credentialId = responseObj.id ?? `test-credential:${userId.toString()}:${Date.now()}`;
+		return {credentialId, publicKey: Buffer.from(`test-public-key:${credentialId}`), counter: 0n, transports, rpId};
+	}
+	let verification: VerifiedRegistrationResponse;
+	try {
+		verification = await verifyRegistrationResponse({
+			response,
+			expectedChallenge,
+			expectedOrigin,
+			expectedRPID: rpId,
+			requireUserVerification: false,
+			supportedAlgorithmIDs: [-8, -7, -257],
+		});
+	} catch (error) {
+		Logger.error({error, userId, expectedChallenge, rpId, expectedOrigin}, 'WebAuthn verification failed');
+		throw new InvalidWebAuthnCredentialError();
+	}
+	if (!verification.verified || !verification.registrationInfo) {
+		Logger.error(
+			{userId, verified: verification.verified, hasRegistrationInfo: !!verification.registrationInfo},
+			'WebAuthn verification result invalid',
+		);
+		throw new InvalidWebAuthnCredentialError();
+	}
+	const {credential} = verification.registrationInfo;
+	let publicKeyBuffer: Buffer;
+	let counterBigInt: bigint;
+	try {
+		publicKeyBuffer = Buffer.from(credential.publicKey);
+	} catch (_error) {
+		throw new InvalidWebAuthnPublicKeyFormatError();
+	}
+	try {
+		if (credential.counter === undefined || credential.counter === null) {
+			throw new Error('Counter value is undefined or null');
+		}
+		counterBigInt = BigInt(credential.counter);
+	} catch (_error) {
+		throw new InvalidWebAuthnCredentialCounterError();
+	}
+	return {credentialId: credential.id, publicKey: publicKeyBuffer, counter: counterBigInt, transports, rpId};
+}
+
 export async function verifyWebAuthnRegistration(
 	ctx: ApiContext,
 	userId: UserID,
@@ -160,85 +286,39 @@ export async function verifyWebAuthnRegistration(
 	expectedChallenge: string,
 	name: string,
 ): Promise<void> {
-	const {users, config} = ctx.services;
+	const {users} = ctx.services;
 	const existingCredentials = await users.listWebAuthnCredentials(userId);
-	await consumeWebAuthnChallenge(ctx, expectedChallenge, 'registration', {userId});
-	if (existingCredentials.length >= 10) {
+	if (visibleWebAuthnCredentials(existingCredentials).length >= 10) {
 		throw new WebAuthnCredentialLimitReachedError();
 	}
-	if (config.dev.testModeEnabled) {
-		const responseObj = response as {id?: string; response?: {transports?: Array<string>}};
-		const credentialId = responseObj.id ?? `test-credential:${userId.toString()}:${Date.now()}`;
-		const publicKeyBuffer = Buffer.from(`test-public-key:${credentialId}`);
-		await users.createWebAuthnCredential(
-			userId,
-			credentialId,
-			publicKeyBuffer,
-			0n,
-			responseObj.response?.transports ? new Set(responseObj.response.transports) : null,
-			name,
-		);
-	} else {
-		const expectedOrigin = config.auth.passkeys.allowedOrigins;
-		const rpID = config.auth.passkeys.rpId;
-		let verification: VerifiedRegistrationResponse;
-		try {
-			verification = await verifyRegistrationResponse({
-				response,
-				expectedChallenge,
-				expectedOrigin,
-				expectedRPID: rpID,
-				requireUserVerification: false,
-				supportedAlgorithmIDs: [-8, -7, -257],
-			});
-		} catch (error) {
-			Logger.error({error, userId, expectedChallenge, rpID, expectedOrigin}, 'WebAuthn verification failed');
-			throw new InvalidWebAuthnCredentialError();
-		}
-		if (!verification.verified || !verification.registrationInfo) {
-			Logger.error(
-				{userId, verified: verification.verified, hasRegistrationInfo: !!verification.registrationInfo},
-				'WebAuthn verification result invalid',
-			);
-			throw new InvalidWebAuthnCredentialError();
-		}
-		const {credential} = verification.registrationInfo;
-		let publicKeyBuffer: Buffer;
-		let counterBigInt: bigint;
-		try {
-			publicKeyBuffer = Buffer.from(credential.publicKey);
-		} catch (_error) {
-			throw new InvalidWebAuthnPublicKeyFormatError();
-		}
-		try {
-			if (credential.counter === undefined || credential.counter === null) {
-				throw new Error('Counter value is undefined or null');
-			}
-			counterBigInt = BigInt(credential.counter);
-		} catch (_error) {
-			throw new InvalidWebAuthnCredentialCounterError();
-		}
-		const responseObj = response as {response?: {transports?: Array<string>}};
-		await users.createWebAuthnCredential(
-			userId,
-			credential.id,
-			publicKeyBuffer,
-			counterBigInt,
-			responseObj.response?.transports ? new Set(responseObj.response.transports) : null,
-			name,
-		);
-	}
+	const verified = await verifyWebAuthnRegistrationResponse(ctx, userId, response, expectedChallenge, 'registration');
+	await users.createWebAuthnCredential(
+		userId,
+		verified.credentialId,
+		verified.publicKey,
+		verified.counter,
+		verified.transports,
+		name,
+		storedRpId(ctx, verified.rpId),
+	);
 	await dispatchWebAuthnCredentialsUpdate(ctx, userId);
 }

 export async function deleteWebAuthnCredential(ctx: ApiContext, userId: UserID, credentialId: string): Promise<void> {
 	const {users, gateway, botMfaMirror} = ctx.services;
 	const credential = await users.getWebAuthnCredential(userId, credentialId);
-	if (!credential) {
+	if (!credential || credential.supersededBy !== null) {
 		throw new UnknownWebAuthnCredentialError();
 	}
 	await users.deleteWebAuthnCredential(userId, credentialId);
-	const remainingCredentials = await users.listWebAuthnCredentials(userId);
+	const remaining = await users.listWebAuthnCredentials(userId);
+	const remainingCredentials = visibleWebAuthnCredentials(remaining);
+	const orphanedTwins = remaining.filter(
+		(cred) => cred.supersededBy === credentialId || (cred.supersededBy !== null && remainingCredentials.length === 0),
+	);
+	for (const twin of orphanedTwins) {
+		await users.deleteWebAuthnCredential(userId, twin.credentialId);
+	}
 	if (remainingCredentials.length === 0) {
 		const user = await users.findUniqueAssert(userId);
 		if (user.authenticatorTypes.has(UserAuthenticatorTypes.WEBAUTHN)) {
@@ -298,37 +378,66 @@ export async function renameWebAuthnCredential(
 ): Promise<void> {
 	const {users} = ctx.services;
 	const credential = await users.getWebAuthnCredential(userId, credentialId);
-	if (!credential) {
+	if (!credential || credential.supersededBy !== null) {
 		throw new UnknownWebAuthnCredentialError();
 	}
 	await users.updateWebAuthnCredentialName(userId, credentialId, name);
 	await dispatchWebAuthnCredentialsUpdate(ctx, userId);
 }

-async function dispatchWebAuthnCredentialsUpdate(ctx: ApiContext, userId: UserID): Promise<void> {
-	const {users, gateway} = ctx.services;
+export async function dispatchWebAuthnCredentialsUpdate(ctx: ApiContext, userId: UserID): Promise<void> {
+	const {users, gateway, config} = ctx.services;
 	const credentials = await users.listWebAuthnCredentials(userId);
 	await gateway.dispatchPresence({
 		userId,
 		event: 'WEBAUTHN_CREDENTIALS_UPDATE',
-		data: credentials.map((cred: WebAuthnCredential) => ({
-			id: cred.credentialId,
-			name: cred.name,
-			created_at: cred.createdAt.toISOString(),
-			last_used_at: cred.lastUsedAt?.toISOString() ?? null,
-		})),
+		data: visibleWebAuthnCredentials(credentials).map((cred) =>
+			mapWebAuthnCredentialToResponse(cred, config.auth.passkeys.rpId),
+		),
 	});
 }

-export async function generateWebAuthnAuthenticationOptionsDiscoverable(ctx: ApiContext) {
+export async function generateWebAuthnAuthenticationOptions(
+	ctx: ApiContext,
+	{selection, context, userId, ticket}: WebAuthnAuthenticationOptionsParams,
+): Promise<PublicKeyCredentialRequestOptionsJSON> {
 	const options = await generateAuthenticationOptions({
-		rpID: ctx.services.config.auth.passkeys.rpId,
-		userVerification: 'required',
+		rpID: selection.rpId,
+		allowCredentials: selection.credentials?.map(toCredentialDescriptor),
+		userVerification: selection.credentials === null ? 'required' : 'discouraged',
+	});
+	await saveWebAuthnChallenge(ctx, options.challenge, {
+		context,
+		userId,
+		ticket,
+		rpId: selection.rpId,
+		credentialIds: selection.credentials?.map((cred) => cred.credentialId) ?? null,
 	});
-	await saveWebAuthnChallenge(ctx, options.challenge, {context: 'discoverable'});
 	return options;
 }

+function selectCredentialRpOrThrow(
+	ctx: ApiContext,
+	origin: string | null | undefined,
+	credentials: Array<WebAuthnCredential>,
+): CredentialRpSelection {
+	const selection = selectCredentialRp(ctx, origin, credentials);
+	if (selection.credentials.length === 0) {
+		throw new NoPasskeysRegisteredError();
+	}
+	return selection;
+}
+
+export async function generateWebAuthnAuthenticationOptionsDiscoverable(
+	ctx: ApiContext,
+	origin: string | null | undefined,
+): Promise<PublicKeyCredentialRequestOptionsJSON> {
+	return generateWebAuthnAuthenticationOptions(ctx, {
+		selection: {rpId: originRpId(ctx, origin), credentials: null},
+		context: 'discoverable',
+	});
+}
+
 export async function verifyWebAuthnAuthenticationDiscoverable(
 	ctx: ApiContext,
 	response: AuthenticationResponseJSON,
@@ -344,29 +453,24 @@ export async function verifyWebAuthnAuthenticationDiscoverable(
 	return users.findUniqueAssert(userId);
 }

-export async function generateWebAuthnAuthenticationOptionsForMfa(ctx: ApiContext, ticket: string) {
-	const {users, cache, config} = ctx.services;
+export async function generateWebAuthnAuthenticationOptionsForMfa(
+	ctx: ApiContext,
+	ticket: string,
+	origin: string | null | undefined,
+): Promise<PublicKeyCredentialRequestOptionsJSON> {
+	const {users, cache} = ctx.services;
 	const userIdStr = await cache.get<string>(`mfa-ticket:${ticket}`);
 	if (!userIdStr) {
 		throw InputValidationError.fromCode('ticket', ValidationErrorCodes.SESSION_TIMEOUT);
 	}
 	const userId = createUserID(BigInt(userIdStr));
 	const credentials = await users.listWebAuthnCredentials(userId);
-	if (credentials.length === 0) {
-		throw new NoPasskeysRegisteredError();
-	}
-	const options = await generateAuthenticationOptions({
-		rpID: config.auth.passkeys.rpId,
-		allowCredentials: credentials.map((cred) => ({
-			id: cred.credentialId,
-			transports: cred.transports
-				? (Array.from(cred.transports) as Array<'usb' | 'nfc' | 'ble' | 'internal' | 'cable' | 'hybrid'>)
-				: undefined,
-		})),
-		userVerification: 'discouraged',
+	return generateWebAuthnAuthenticationOptions(ctx, {
+		selection: selectCredentialRpOrThrow(ctx, origin, credentials),
+		context: 'mfa',
+		userId,
+		ticket,
 	});
-	await saveWebAuthnChallenge(ctx, options.challenge, {context: 'mfa', userId, ticket});
-	return options;
 }

 export async function verifyWebAuthnAuthentication(
@@ -376,21 +480,26 @@ export async function verifyWebAuthnAuthentication(
 	expectedChallenge: string,
 	context: WebAuthnChallengeContext = 'mfa',
 	ticket?: string,
-): Promise<void> {
+	expectedOrigin: Array<string> = ctx.services.config.auth.passkeys.allowedOrigins,
+): Promise<WebAuthnCredential> {
 	const {users, config} = ctx.services;
-	await consumeWebAuthnChallenge(ctx, expectedChallenge, context, {userId, ticket});
+	const scope = await consumeWebAuthnChallenge(ctx, expectedChallenge, context, {userId, ticket});
 	const credentialId = (response as {id: string}).id;
 	const credential = await users.getWebAuthnCredential(userId, credentialId);
 	if (!credential) {
 		throw new PasskeyAuthenticationFailedError();
 	}
+	if (
+		effectiveRpId(ctx, credential) !== scope.rpId ||
+		(scope.credentialIds !== null && !scope.credentialIds.includes(credentialId))
+	) {
+		throw new PasskeyAuthenticationFailedError();
+	}
 	if (config.dev.testModeEnabled) {
 		await users.updateWebAuthnCredentialCounter(userId, credentialId, credential.counter + 1n);
 		await users.updateWebAuthnCredentialLastUsed(userId, credentialId);
-		return;
+		return credential;
 	}
-	const expectedOrigin = config.auth.passkeys.allowedOrigins;
-	const rpID = config.auth.passkeys.rpId;
 	let verification: VerifiedAuthenticationResponse;
 	try {
 		let publicKeyUint8Array: Uint8Array<ArrayBuffer>;
@@ -405,15 +514,12 @@ export async function verifyWebAuthnAuthentication(
 			response,
 			expectedChallenge,
 			expectedOrigin,
-			expectedRPID: rpID,
-			requireUserVerification: requiresWebAuthnUserVerification(context),
+			expectedRPID: scope.rpId,
+			requireUserVerification: requiresWebAuthnUserVerification(context, scope),
 			credential: {
-				id: credential.credentialId,
+				...toCredentialDescriptor(credential),
 				publicKey: publicKeyUint8Array,
 				counter: Number(credential.counter),
-				transports: credential.transports
-					? (Array.from(credential.transports) as Array<'usb' | 'nfc' | 'ble' | 'internal' | 'cable' | 'hybrid'>)
-					: undefined,
 			},
 		});
 	} catch (_error) {
@@ -434,31 +540,25 @@ export async function verifyWebAuthnAuthentication(
 	}
 	await users.updateWebAuthnCredentialCounter(userId, credentialId, newCounter);
 	await users.updateWebAuthnCredentialLastUsed(userId, credentialId);
+	return credential;
 }

-export async function generateWebAuthnOptionsForSudo(ctx: ApiContext, userId: UserID) {
-	const {users, config} = ctx.services;
-	const credentials = await users.listWebAuthnCredentials(userId);
-	if (credentials.length === 0) {
-		throw new NoPasskeysRegisteredError();
-	}
-	const options = await generateAuthenticationOptions({
-		rpID: config.auth.passkeys.rpId,
-		allowCredentials: credentials.map((cred) => ({
-			id: cred.credentialId,
-			transports: cred.transports
-				? (Array.from(cred.transports) as Array<'usb' | 'nfc' | 'ble' | 'internal' | 'cable' | 'hybrid'>)
-				: undefined,
-		})),
-		userVerification: 'discouraged',
+export async function generateWebAuthnOptionsForSudo(
+	ctx: ApiContext,
+	userId: UserID,
+	origin: string | null | undefined,
+): Promise<PublicKeyCredentialRequestOptionsJSON> {
+	const credentials = await ctx.services.users.listWebAuthnCredentials(userId);
+	return generateWebAuthnAuthenticationOptions(ctx, {
+		selection: selectCredentialRpOrThrow(ctx, origin, credentials),
+		context: 'sudo',
+		userId,
 	});
-	await saveWebAuthnChallenge(ctx, options.challenge, {context: 'sudo', userId});
-	return options;
 }

 const SUDO_MFA_USER_MAX_ATTEMPTS = 10;

-async function consumeSudoMfaAttempt(ctx: ApiContext, userId: UserID): Promise<void> {
+export async function consumeSudoMfaAttempt(ctx: ApiContext, userId: UserID): Promise<void> {
 	const {rateLimit} = ctx.services;
 	const userLimit = await rateLimit.checkLimit({
 		identifier: `sudo-mfa:user:${userId}`,
@@ -535,20 +635,33 @@ function webAuthnChallengeCacheKey(challenge: string): string {
 	return `webauthn:challenge:${challenge}`;
 }

-function requiresWebAuthnUserVerification(context: WebAuthnChallengeContext): boolean {
-	return context === 'discoverable';
+function requiresWebAuthnUserVerification(context: WebAuthnChallengeContext, scope: WebAuthnChallengeScope): boolean {
+	return context === 'discoverable' || (context === 'bridge' && scope.credentialIds === null);
 }

 async function saveWebAuthnChallenge(
 	ctx: ApiContext,
 	challenge: string,
-	entry: {context: WebAuthnChallengeContext; userId?: UserID; ticket?: string},
+	entry: {
+		context: WebAuthnChallengeContext;
+		userId?: UserID;
+		ticket?: string;
+		rpId: string;
+		credentialIds: Array<string> | null;
+	},
 ): Promise<void> {
-	await ctx.services.cache.set(
-		webAuthnChallengeCacheKey(challenge),
-		{context: entry.context, userId: entry.userId?.toString(), ticket: entry.ticket},
-		seconds('5 minutes'),
-	);
+	const value: WebAuthnChallengeEntry = {
+		context: entry.context,
+		userId: entry.userId?.toString(),
+		ticket: entry.ticket,
+		rpId: entry.rpId,
+		credentialIds: entry.credentialIds,
+	};
+	await ctx.services.cache.set(webAuthnChallengeCacheKey(challenge), value, seconds('5 minutes'));
+}
+
+export async function deleteWebAuthnChallenge(ctx: ApiContext, challenge: string): Promise<void> {
+	await ctx.services.cache.delete(webAuthnChallengeCacheKey(challenge));
 }

 async function consumeWebAuthnChallenge(
@@ -556,10 +669,8 @@ async function consumeWebAuthnChallenge(
 	challenge: string,
 	expectedContext: WebAuthnChallengeContext,
 	{userId, ticket}: {userId?: UserID; ticket?: string} = {},
-): Promise<void> {
-	const {cache} = ctx.services;
-	const key = webAuthnChallengeCacheKey(challenge);
-	const cached = await cache.get<{context: WebAuthnChallengeContext; userId?: string; ticket?: string}>(key);
+): Promise<WebAuthnChallengeScope> {
+	const cached = await ctx.services.cache.getAndDelete<WebAuthnChallengeEntry>(webAuthnChallengeCacheKey(challenge));
 	const challengeMatches =
 		cached &&
 		cached.context === expectedContext &&
@@ -581,11 +692,14 @@ async function consumeWebAuthnChallenge(
 		);
 		throw createChallengeError(expectedContext);
 	}
-	await cache.delete(key);
+	return {
+		rpId: cached.rpId ?? ctx.services.config.auth.passkeys.rpId,
+		credentialIds: cached.credentialIds ?? null,
+	};
 }

 function createChallengeError(context: WebAuthnChallengeContext) {
-	if (context === 'registration') {
+	if (context === 'registration' || context === 'migration_registration') {
 		return new InvalidWebAuthnCredentialError();
 	}
 	return new PasskeyAuthenticationFailedError();
@@ -8,12 +8,19 @@ import * as AuthMfa from '@app/api/auth/AuthMfa';
 import * as AuthPassword from '@app/api/auth/AuthPassword';
 import * as AuthRegistration from '@app/api/auth/AuthRegistration';
 import * as AuthSession from '@app/api/auth/AuthSession';
+import {getTokenIdHash} from '@app/api/auth/AuthUtility';
 import type {DesktopHandoffService} from '@app/api/auth/services/DesktopHandoffService';
 import type {SsoService} from '@app/api/auth/services/SsoService';
 import {createUserID, type UserID} from '@app/api/BrandedTypes';
+import {Logger} from '@app/api/Logger';
 import type {RequestCache} from '@app/api/middleware/RequestCacheMiddleware';
 import {getInstanceConfigRepository} from '@app/api/middleware/ServiceSingletons';
 import type {User} from '@app/api/models/User';
+import {
+	classifyWebPushOrigin,
+	encodePushSessionIdHash,
+	recordPushSessionPredecessor,
+} from '@app/api/user/services/WebPushOriginReplacement';
 import {mapUserToPartialResponse} from '@app/api/user/UserMappers';
 import {lookupGeoip} from '@app/api/utils/IpUtils';
 import {parseJsonRecord} from '@app/api/utils/JsonBoundaryUtils';
@@ -91,6 +98,7 @@ interface AuthHandoffCompleteRequest {
 	data: HandoffCompleteRequest;
 	clientIp: string;
 	authToken?: string;
+	approverOrigin?: string | null;
 }

 interface AuthAuthorizeIpRequest {
@@ -272,21 +280,18 @@ export class AuthRequestService {
 		return {completed: false};
 	}

-	async getWebAuthnAuthenticationOptions() {
-		return AuthMfa.generateWebAuthnAuthenticationOptionsDiscoverable(this.apiContext);
+	async getWebAuthnAuthenticationOptions(origin: string | undefined) {
+		return AuthMfa.generateWebAuthnAuthenticationOptionsDiscoverable(this.apiContext, origin);
 	}

 	async authenticateWebAuthnDiscoverable({data, request}: AuthWebAuthnAuthenticateRequest) {
 		const user = await AuthMfa.verifyWebAuthnAuthenticationDiscoverable(this.apiContext, data.response, data.challenge);
-		const [token] = await AuthSession.createAuthSession(this.apiContext, {
-			user,
-			origin: AuthSession.resolveSessionOrigin(this.apiContext, request),
-		});
+		const [token] = await AuthLogin.createLoginSession(this.apiContext, user, request);
 		return {token, user_id: user.id.toString(), user: mapUserToPartialResponse(user)};
 	}

-	async getWebAuthnMfaOptions({ticket}: MfaTicketRequest) {
-		return AuthMfa.generateWebAuthnAuthenticationOptionsForMfa(this.apiContext, ticket);
+	async getWebAuthnMfaOptions({ticket}: MfaTicketRequest, origin: string | undefined) {
+		return AuthMfa.generateWebAuthnAuthenticationOptionsForMfa(this.apiContext, ticket, origin);
 	}

 	async loginMfaWebAuthn({data, request}: AuthWebAuthnMfaRequest): Promise<AuthTokenWithUserIdResponse> {
@@ -305,7 +310,10 @@ export class AuthRequestService {

 	async initiateHandoff({request}: AuthHandoffInitiateRequest): Promise<HandoffInitiateResponse> {
 		const origin = AuthSession.resolveSessionOrigin(this.apiContext, request);
-		const result = await this.desktopHandoffService.initiateHandoff({origin});
+		const result = await this.desktopHandoffService.initiateHandoff({
+			origin,
+			initiatorOrigin: request.headers.get('origin'),
+		});
 		return {
 			code: result.code,
 			expires_at: result.expiresAt.toISOString(),
@@ -340,21 +348,53 @@ export class AuthRequestService {
 		};
 	}

-	async completeHandoff({data, clientIp, authToken}: AuthHandoffCompleteRequest): Promise<void> {
+	async completeHandoff({data, clientIp, authToken, approverOrigin}: AuthHandoffCompleteRequest): Promise<void> {
 		const sessionToken = data.token ?? authToken;
 		if (!sessionToken) {
 			throw new UnauthorizedError();
 		}
-		await this.desktopHandoffService.completeHandoff(
+		let createdToken: string | null = null;
+		const {initiatorOrigin} = await this.desktopHandoffService.completeHandoff(
 			data.code,
-			(origin) =>
-				AuthSession.createAdditionalAuthSessionFromToken(this.apiContext, {
+			async (origin) => {
+				const created = await AuthSession.createAdditionalAuthSessionFromToken(this.apiContext, {
 					token: sessionToken,
 					expectedUserId: data.user_id,
 					origin,
-				}),
+				});
+				createdToken = created.token;
+				return created;
+			},
 			clientIp,
 		);
+		if (createdToken !== null) {
+			await this.recordPushSessionPredecessor(createdToken, sessionToken, initiatorOrigin, approverOrigin);
+		}
+	}
+
+	private async recordPushSessionPredecessor(
+		createdToken: string,
+		approverToken: string,
+		initiatorOrigin: string | null,
+		approverOrigin: string | null | undefined,
+	): Promise<void> {
+		const {config, kv} = this.apiContext.services;
+		const {selfHosted} = config.instance;
+		if (
+			classifyWebPushOrigin(initiatorOrigin, selfHosted) !== 'target' ||
+			classifyWebPushOrigin(approverOrigin, selfHosted) !== 'legacy'
+		) {
+			return;
+		}
+		try {
+			await recordPushSessionPredecessor(
+				kv,
+				encodePushSessionIdHash(getTokenIdHash(this.apiContext, createdToken)),
+				encodePushSessionIdHash(getTokenIdHash(this.apiContext, approverToken)),
+			);
+		} catch (error) {
+			Logger.warn({error}, 'Failed to record the push session predecessor');
+		}
 	}

 	async getHandoffStatus({code, clientIp, pollSecret}: AuthHandoffStatusRequest): Promise<HandoffStatusResponse> {
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import {createOriginHandoff, redeemOriginHandoff} from '@app/api/auth/services/OriginHandoffService';
+import {Config} from '@app/api/Config';
+import {DefaultUserOnly, LoginRequired} from '@app/api/middleware/AuthMiddleware';
+import {RateLimitMiddleware} from '@app/api/middleware/RateLimitMiddleware';
+import {OpenAPI} from '@app/api/middleware/ResponseTypeMiddleware';
+import {RateLimitConfigs} from '@app/api/RateLimitConfig';
+import type {HonoApp} from '@app/api/types/HonoEnv';
+import {Validator} from '@app/api/Validator';
+import {FileSizeTooLargeError} from '@fluxer/errors/src/domains/core/FileSizeTooLargeError';
+import {InvalidApiOriginError} from '@fluxer/errors/src/domains/core/InvalidApiOriginError';
+import {
+	ORIGIN_HANDOFF_MAX_PAYLOAD_LENGTH,
+	OriginHandoffCreateRequest,
+	OriginHandoffCreateResponse,
+	OriginHandoffRedeemRequest,
+	OriginHandoffRedeemResponse,
+} from '@fluxer/schema/src/domains/auth/OriginHandoffSchemas';
+import {bodyLimit} from 'hono/body-limit';
+
+const ORIGIN_HANDOFF_CREATE_MAX_BODY_BYTES = ORIGIN_HANDOFF_MAX_PAYLOAD_LENGTH + 1024;
+
+export function OriginHandoffController(app: HonoApp) {
+	app.post(
+		'/auth/origin-handoff',
+		RateLimitMiddleware(RateLimitConfigs.AUTH_ORIGIN_HANDOFF_CREATE),
+		LoginRequired,
+		DefaultUserOnly,
+		bodyLimit({
+			maxSize: ORIGIN_HANDOFF_CREATE_MAX_BODY_BYTES,
+			onError: () => {
+				throw new FileSizeTooLargeError(ORIGIN_HANDOFF_CREATE_MAX_BODY_BYTES);
+			},
+		}),
+		Validator('json', OriginHandoffCreateRequest),
+		OpenAPI({
+			operationId: 'create_origin_handoff',
+			summary: 'Create origin handoff',
+			responseSchema: OriginHandoffCreateResponse,
+			statusCode: 200,
+			security: ['sessionToken'],
+			tags: ['Auth'],
+			description:
+				'Store encrypted client state for up to two minutes so another first-party web origin can redeem it once. The receiving origin must present the nonce whose SHA-256 digest is sent here.',
+		}),
+		async (ctx) => {
+			const body = ctx.req.valid('json');
+			const handoffId = await createOriginHandoff(ctx.get('cacheService'), {
+				userId: ctx.get('user').id,
+				nonceHash: body.nonce_hash,
+				payload: body.payload,
+			});
+			const response: OriginHandoffCreateResponse = {handoff_id: handoffId};
+			return ctx.json(response);
+		},
+	);
+	app.post(
+		'/auth/origin-handoff/redeem',
+		RateLimitMiddleware(RateLimitConfigs.AUTH_ORIGIN_HANDOFF_REDEEM),
+		Validator('json', OriginHandoffRedeemRequest),
+		OpenAPI({
+			operationId: 'redeem_origin_handoff',
+			summary: 'Redeem origin handoff',
+			responseSchema: OriginHandoffRedeemResponse,
+			statusCode: 200,
+			security: [],
+			tags: ['Auth'],
+			description:
+				'Return the encrypted client state stored by create origin handoff and delete it in the same step. A wrong nonce also consumes the handoff. On the official instance the request must come from a first-party web origin.',
+		}),
+		async (ctx) => {
+			if (!Config.instance.selfHosted) {
+				const origin = ctx.req.header('origin');
+				if (origin === undefined || !Config.endpoints.webAppOrigins.includes(origin)) {
+					throw new InvalidApiOriginError();
+				}
+			}
+			const body = ctx.req.valid('json');
+			const payload = await redeemOriginHandoff(ctx.get('cacheService'), {
+				handoffId: body.handoff_id,
+				nonce: body.nonce,
+			});
+			const response: OriginHandoffRedeemResponse = {payload};
+			return ctx.json(response);
+		},
+	);
+}
@@ -0,0 +1,205 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import {
+	cancelPasskeyBridge,
+	completePasskeyBridge,
+	getPasskeyBridgeOptions,
+	redeemPasskeyBridgeLogin,
+	redeemPasskeyBridgeSudo,
+	startPasskeyBridgeLogin,
+	startPasskeyBridgeSudo,
+} from '@app/api/auth/services/PasskeyBridgeService';
+import {DefaultUserOnly, LoginRequired} from '@app/api/middleware/AuthMiddleware';
+import {LocalAuthMiddleware} from '@app/api/middleware/LocalAuthMiddleware';
+import {RateLimitMiddleware} from '@app/api/middleware/RateLimitMiddleware';
+import {OpenAPI} from '@app/api/middleware/ResponseTypeMiddleware';
+import {RateLimitConfigs} from '@app/api/RateLimitConfig';
+import type {HonoApp} from '@app/api/types/HonoEnv';
+import {Validator} from '@app/api/Validator';
+import {
+	PasskeyBridgeCeremonyIdParam,
+	PasskeyBridgeCompleteRequest,
+	PasskeyBridgeFinishResponse,
+	PasskeyBridgeLoginRedeemResponse,
+	PasskeyBridgeLoginStartRequest,
+	PasskeyBridgeOptionsResponse,
+	PasskeyBridgeRedeemRequest,
+	PasskeyBridgeStartResponse,
+	PasskeyBridgeSudoRedeemResponse,
+	PasskeyBridgeSudoStartRequest,
+} from '@fluxer/schema/src/domains/auth/PasskeyBridgeSchemas';
+
+export function PasskeyBridgeController(app: HonoApp) {
+	app.post(
+		'/auth/passkey-bridge',
+		LocalAuthMiddleware,
+		RateLimitMiddleware(RateLimitConfigs.AUTH_PASSKEY_BRIDGE_START),
+		Validator('json', PasskeyBridgeLoginStartRequest),
+		OpenAPI({
+			operationId: 'start_passkey_bridge_login',
+			summary: 'Start passkey bridge sign in',
+			responseSchema: PasskeyBridgeStartResponse,
+			statusCode: 200,
+			security: [],
+			tags: ['Auth'],
+			description:
+				'Start a sign in or two-factor ceremony for a passkey that belongs to the paired first-party origin. Only available on the official instance from the new origin.',
+		}),
+		async (ctx) => {
+			return ctx.json(
+				await startPasskeyBridgeLogin(ctx.get('apiContext'), ctx.req.header('origin'), ctx.req.valid('json')),
+			);
+		},
+	);
+	app.post(
+		'/users/@me/passkey-bridge',
+		RateLimitMiddleware(RateLimitConfigs.USER_PASSKEY_BRIDGE_START),
+		LoginRequired,
+		DefaultUserOnly,
+		Validator('json', PasskeyBridgeSudoStartRequest),
+		OpenAPI({
+			operationId: 'start_passkey_bridge_sudo',
+			summary: 'Start passkey bridge sudo verification',
+			responseSchema: PasskeyBridgeStartResponse,
+			statusCode: 200,
+			security: ['bearerToken', 'sessionToken'],
+			tags: ['Users'],
+			description:
+				'Start a sudo verification ceremony for a passkey that belongs to the paired first-party origin. Only available on the official instance from the new origin.',
+		}),
+		async (ctx) => {
+			return ctx.json(
+				await startPasskeyBridgeSudo(
+					ctx.get('apiContext'),
+					ctx.req.header('origin'),
+					ctx.get('user').id,
+					ctx.req.valid('json'),
+				),
+			);
+		},
+	);
+	app.post(
+		'/auth/passkey-bridge/:ceremony_id/options',
+		RateLimitMiddleware(RateLimitConfigs.AUTH_PASSKEY_BRIDGE_CEREMONY),
+		Validator('param', PasskeyBridgeCeremonyIdParam),
+		OpenAPI({
+			operationId: 'get_passkey_bridge_options',
+			summary: 'Get passkey bridge options',
+			responseSchema: PasskeyBridgeOptionsResponse,
+			statusCode: 200,
+			security: [],
+			tags: ['Auth'],
+			description:
+				'Issue WebAuthn authentication options for a pending passkey bridge ceremony. The request must come from the origin that runs the ceremony.',
+		}),
+		async (ctx) => {
+			const {ceremony_id} = ctx.req.valid('param');
+			return ctx.json(await getPasskeyBridgeOptions(ctx.get('apiContext'), ceremony_id, ctx.req.header('origin')));
+		},
+	);
+	app.post(
+		'/auth/passkey-bridge/:ceremony_id/complete',
+		RateLimitMiddleware(RateLimitConfigs.AUTH_PASSKEY_BRIDGE_CEREMONY),
+		Validator('param', PasskeyBridgeCeremonyIdParam),
+		Validator('json', PasskeyBridgeCompleteRequest),
+		OpenAPI({
+			operationId: 'complete_passkey_bridge',
+			summary: 'Complete passkey bridge',
+			responseSchema: PasskeyBridgeFinishResponse,
+			statusCode: 200,
+			security: [],
+			tags: ['Auth'],
+			description:
+				'Verify the WebAuthn response for a pending passkey bridge ceremony. A failed verification leaves the ceremony pending so it can be retried.',
+		}),
+		async (ctx) => {
+			const {ceremony_id} = ctx.req.valid('param');
+			return ctx.json(
+				await completePasskeyBridge(
+					ctx.get('apiContext'),
+					ceremony_id,
+					ctx.req.header('origin'),
+					ctx.req.valid('json'),
+				),
+			);
+		},
+	);
+	app.post(
+		'/auth/passkey-bridge/:ceremony_id/cancel',
+		RateLimitMiddleware(RateLimitConfigs.AUTH_PASSKEY_BRIDGE_CEREMONY),
+		Validator('param', PasskeyBridgeCeremonyIdParam),
+		OpenAPI({
+			operationId: 'cancel_passkey_bridge',
+			summary: 'Cancel passkey bridge',
+			responseSchema: PasskeyBridgeFinishResponse,
+			statusCode: 200,
+			security: [],
+			tags: ['Auth'],
+			description: 'Cancel a passkey bridge ceremony that has not completed.',
+		}),
+		async (ctx) => {
+			const {ceremony_id} = ctx.req.valid('param');
+			return ctx.json(await cancelPasskeyBridge(ctx.get('apiContext'), ceremony_id, ctx.req.header('origin')));
+		},
+	);
+	app.post(
+		'/auth/passkey-bridge/:ceremony_id/redeem',
+		LocalAuthMiddleware,
+		RateLimitMiddleware(RateLimitConfigs.AUTH_PASSKEY_BRIDGE_REDEEM),
+		Validator('param', PasskeyBridgeCeremonyIdParam),
+		Validator('json', PasskeyBridgeRedeemRequest),
+		OpenAPI({
+			operationId: 'redeem_passkey_bridge_login',
+			summary: 'Redeem passkey bridge sign in',
+			responseSchema: PasskeyBridgeLoginRedeemResponse,
+			statusCode: 200,
+			security: [],
+			tags: ['Auth'],
+			description:
+				'Redeem a finished sign in or two-factor passkey bridge ceremony once. Requires the nonce kept by the starting page and the completion code handed back when the ceremony finished.',
+		}),
+		async (ctx) => {
+			const {ceremony_id} = ctx.req.valid('param');
+			return ctx.json(
+				await redeemPasskeyBridgeLogin(
+					ctx.get('apiContext'),
+					ceremony_id,
+					ctx.req.header('origin'),
+					ctx.req.valid('json'),
+					ctx.req.raw,
+				),
+			);
+		},
+	);
+	app.post(
+		'/users/@me/passkey-bridge/:ceremony_id/redeem',
+		RateLimitMiddleware(RateLimitConfigs.USER_PASSKEY_BRIDGE_REDEEM),
+		LoginRequired,
+		DefaultUserOnly,
+		Validator('param', PasskeyBridgeCeremonyIdParam),
+		Validator('json', PasskeyBridgeRedeemRequest),
+		OpenAPI({
+			operationId: 'redeem_passkey_bridge_sudo',
+			summary: 'Redeem passkey bridge sudo verification',
+			responseSchema: PasskeyBridgeSudoRedeemResponse,
+			statusCode: 200,
+			security: ['bearerToken', 'sessionToken'],
+			tags: ['Users'],
+			description:
+				'Redeem a finished sudo passkey bridge ceremony once for a sudo mode token. Requires the nonce kept by the starting page and the completion code handed back when the ceremony finished.',
+		}),
+		async (ctx) => {
+			const {ceremony_id} = ctx.req.valid('param');
+			return ctx.json(
+				await redeemPasskeyBridgeSudo(
+					ctx.get('apiContext'),
+					ceremony_id,
+					ctx.req.header('origin'),
+					ctx.req.valid('json'),
+					ctx.get('user').id,
+					ctx.get('authSession'),
+				),
+			);
+		},
+	);
+}
@@ -25,6 +25,7 @@ const POLL_SECRET_BYTES = 32;
 interface HandoffData {
 	createdAt: number;
 	origin: SessionOrigin;
+	initiatorOrigin?: string | null;
 	infoLookupCount: number;
 	pollSecretHash: string;
 }
@@ -84,7 +85,7 @@ function pollSecretMatches(presented: string | undefined, storedHash: string | u
 export class DesktopHandoffService {
 	constructor(private readonly apiContext: ApiContext) {}

-	async initiateHandoff(args: {origin: SessionOrigin}): Promise<{
+	async initiateHandoff(args: {origin: SessionOrigin; initiatorOrigin?: string | null}): Promise<{
 		code: string;
 		expiresAt: Date;
 		pollSecret: string;
@@ -95,6 +96,7 @@ export class DesktopHandoffService {
 		const handoffData: HandoffData = {
 			createdAt: Date.now(),
 			origin: args.origin,
+			initiatorOrigin: args.initiatorOrigin ?? null,
 			infoLookupCount: 0,
 			pollSecretHash: hashPollSecret(pollSecret),
 		};
@@ -108,7 +110,7 @@ export class DesktopHandoffService {
 		code: string,
 		createTokenData: (origin: SessionOrigin) => Promise<{token: string; userId: string}>,
 		approverIp: string,
-	): Promise<void> {
+	): Promise<{initiatorOrigin: string | null}> {
 		const {cache} = this.apiContext.services;
 		const normalizedCode = requireNormalizedHandoffCode(code);
 		await this.checkAttemptLimit(approverIp);
@@ -138,6 +140,7 @@ export class DesktopHandoffService {
 		await cache.set(`${HANDOFF_TOKEN_PREFIX}${normalizedCode}`, tokenData, remainingSeconds);
 		await cache.delete(`${HANDOFF_CODE_PREFIX}${normalizedCode}`);
 		await cache.delete(`${HANDOFF_APPROVER_PREFIX}${normalizedCode}`);
+		return {initiatorOrigin: handoffData.initiatorOrigin ?? null};
 	}

 	async getHandoffInfo(
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import {createHash, randomBytes, timingSafeEqual} from 'node:crypto';
+import type {UserID} from '@app/api/BrandedTypes';
+import {InvalidOriginHandoffNonceError} from '@fluxer/errors/src/domains/auth/InvalidOriginHandoffNonceError';
+import {UnknownOriginHandoffError} from '@fluxer/errors/src/domains/auth/UnknownOriginHandoffError';
+import type {ICacheService} from '@pkgs/cache/src/ICacheService';
+import {seconds} from 'itty-time';
+
+const ORIGIN_HANDOFF_KEY_PREFIX = 'origin_handoff:';
+const ORIGIN_HANDOFF_ID_BYTES = 32;
+
+interface OriginHandoffRecord {
+	nonce_hash: string;
+	payload: string;
+	user_id: string;
+	created_at: number;
+}
+
+function sha256Hex(value: string): string {
+	return createHash('sha256').update(value).digest('hex');
+}
+
+function originHandoffKey(handoffId: string): string {
+	return `${ORIGIN_HANDOFF_KEY_PREFIX}${sha256Hex(handoffId)}`;
+}
+
+export async function createOriginHandoff(
+	cache: ICacheService,
+	args: {userId: UserID; nonceHash: string; payload: string},
+): Promise<string> {
+	const handoffId = randomBytes(ORIGIN_HANDOFF_ID_BYTES).toString('base64url');
+	const record: OriginHandoffRecord = {
+		nonce_hash: args.nonceHash,
+		payload: args.payload,
+		user_id: args.userId.toString(),
+		created_at: Date.now(),
+	};
+	await cache.set(originHandoffKey(handoffId), record, seconds('2 minutes'));
+	return handoffId;
+}
+
+export async function redeemOriginHandoff(
+	cache: ICacheService,
+	args: {handoffId: string; nonce: string},
+): Promise<string> {
+	const record = await cache.getAndDelete<OriginHandoffRecord>(originHandoffKey(args.handoffId));
+	if (!record) {
+		throw new UnknownOriginHandoffError();
+	}
+	const presented = Buffer.from(sha256Hex(args.nonce), 'hex');
+	const stored = Buffer.from(record.nonce_hash, 'hex');
+	if (presented.length !== stored.length || !timingSafeEqual(presented, stored)) {
+		throw new InvalidOriginHandoffNonceError();
+	}
+	return record.payload;
+}
@@ -0,0 +1,436 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import {createHash, randomBytes, timingSafeEqual} from 'node:crypto';
+import type {ApiContext} from '@app/api/ApiContext';
+import * as AuthLogin from '@app/api/auth/AuthLogin';
+import * as AuthMfa from '@app/api/auth/AuthMfa';
+import * as AuthUtility from '@app/api/auth/AuthUtility';
+import {recordPendingPasskeyMigration} from '@app/api/auth/services/PasskeyMigrationService';
+import {
+	effectiveRpId,
+	isPasskeyMigrationActive,
+	isPasskeyTargetOrigin,
+	passkeyLegacyOriginFor,
+	visibleWebAuthnCredentials,
+} from '@app/api/auth/services/PasskeyRelyingParty';
+import {getSudoModeService} from '@app/api/auth/services/SudoModeService';
+import {resolveWebAuthnSecondFactor} from '@app/api/auth/services/WebAuthnSecondFactor';
+import {createUserID, type UserID} from '@app/api/BrandedTypes';
+import type {AuthSession} from '@app/api/models/AuthSession';
+import type {User} from '@app/api/models/User';
+import type {WebAuthnCredential} from '@app/api/models/WebAuthnCredential';
+import {mapUserToPartialResponse} from '@app/api/user/UserMappers';
+import {PASSKEY_BRIDGE_PATH, PASSKEY_BRIDGE_RETURN_FRAGMENT_KEY} from '@fluxer/constants/src/PasskeyConstants';
+import {ValidationErrorCodes} from '@fluxer/constants/src/ValidationErrorCodes';
+import {InvalidPasskeyBridgeNonceError} from '@fluxer/errors/src/domains/auth/InvalidPasskeyBridgeNonceError';
+import {MfaNotEnabledError} from '@fluxer/errors/src/domains/auth/MfaNotEnabledError';
+import {NoPasskeysRegisteredError} from '@fluxer/errors/src/domains/auth/NoPasskeysRegisteredError';
+import {PasskeyAuthenticationFailedError} from '@fluxer/errors/src/domains/auth/PasskeyAuthenticationFailedError';
+import {UnknownPasskeyBridgeError} from '@fluxer/errors/src/domains/auth/UnknownPasskeyBridgeError';
+import {InputValidationError} from '@fluxer/errors/src/domains/core/InputValidationError';
+import {InvalidApiOriginError} from '@fluxer/errors/src/domains/core/InvalidApiOriginError';
+import type {
+	PasskeyBridgeCompleteRequest,
+	PasskeyBridgeFinishResponse,
+	PasskeyBridgeLoginRedeemResponse,
+	PasskeyBridgeLoginStartRequest,
+	PasskeyBridgeRedeemRequest,
+	PasskeyBridgeRunner,
+	PasskeyBridgeStartResponse,
+	PasskeyBridgeSudoRedeemResponse,
+	PasskeyBridgeSudoStartRequest,
+} from '@fluxer/schema/src/domains/auth/PasskeyBridgeSchemas';
+import type {PublicKeyCredentialRequestOptionsJSON} from '@simplewebauthn/server';
+import {ms, seconds} from 'itty-time';
+
+type PasskeyBridgePurpose = 'login' | 'login_mfa' | 'sudo';
+
+interface PasskeyBridgeRecord {
+	purpose: PasskeyBridgePurpose;
+	runner: PasskeyBridgeRunner;
+	target_origin: string;
+	ceremony_origin: string;
+	nonce_hash: string;
+	user_id: string | null;
+	ticket: string | null;
+	challenge: string | null;
+	credential_id: string | null;
+	cross_device: boolean;
+	completion_code_hash: string | null;
+	status: 'pending' | 'completed' | 'cancelled';
+	created_at: number;
+	expires_at: number;
+}
+
+interface CompletedPasskeyBridge {
+	record: PasskeyBridgeRecord;
+	userId: UserID;
+}
+
+const PASSKEY_BRIDGE_KEY_PREFIX = 'passkey_bridge:';
+const PASSKEY_BRIDGE_LOCK_PREFIX = 'passkey_bridge_lock:';
+const PASSKEY_BRIDGE_SECRET_BYTES = 32;
+
+function sha256Hex(value: string): string {
+	return createHash('sha256').update(value).digest('hex');
+}
+
+function hashMatches(value: string, storedHash: string | null): boolean {
+	if (storedHash === null) return false;
+	const presented = Buffer.from(sha256Hex(value), 'hex');
+	const stored = Buffer.from(storedHash, 'hex');
+	return presented.length === stored.length && timingSafeEqual(presented, stored);
+}
+
+function createSecret(): string {
+	return randomBytes(PASSKEY_BRIDGE_SECRET_BYTES).toString('base64url');
+}
+
+function passkeyBridgeKey(ceremonyId: string): string {
+	return `${PASSKEY_BRIDGE_KEY_PREFIX}${sha256Hex(ceremonyId)}`;
+}
+
+async function writeRecord(ctx: ApiContext, ceremonyId: string, record: PasskeyBridgeRecord): Promise<void> {
+	const ttlSeconds = Math.floor((record.expires_at - Date.now()) / 1000);
+	if (ttlSeconds <= 0) {
+		throw new UnknownPasskeyBridgeError();
+	}
+	await ctx.services.cache.set(passkeyBridgeKey(ceremonyId), record, ttlSeconds);
+}
+
+function assertCeremonyOrigin(
+	ctx: ApiContext,
+	record: PasskeyBridgeRecord,
+	origin: string | undefined,
+	expectedOrigin: string,
+): void {
+	if (origin !== expectedOrigin || !isPasskeyTargetOrigin(ctx, record.target_origin)) {
+		throw new InvalidApiOriginError();
+	}
+}
+
+async function mutateRecord<T>(
+	ctx: ApiContext,
+	ceremonyId: string,
+	origin: string | undefined,
+	mutate: (record: PasskeyBridgeRecord) => Promise<T>,
+): Promise<T> {
+	const {cache} = ctx.services;
+	const lockKey = `${PASSKEY_BRIDGE_LOCK_PREFIX}${sha256Hex(ceremonyId)}`;
+	const lockToken = await cache.acquireLock(lockKey, seconds('10 seconds'));
+	if (!lockToken) {
+		throw new UnknownPasskeyBridgeError();
+	}
+	try {
+		const record = await cache.get<PasskeyBridgeRecord>(passkeyBridgeKey(ceremonyId));
+		if (!record) {
+			throw new UnknownPasskeyBridgeError();
+		}
+		assertCeremonyOrigin(ctx, record, origin, record.ceremony_origin);
+		return await mutate(record);
+	} finally {
+		await cache.releaseLock(lockKey, lockToken);
+	}
+}
+
+async function requireMfaTicketUser(ctx: ApiContext, ticket: string, expectedUserId?: string): Promise<User> {
+	const userId = await ctx.services.cache.get<string>(`mfa-ticket:${ticket}`);
+	if (!userId || (expectedUserId !== undefined && userId !== expectedUserId)) {
+		throw InputValidationError.fromCode('ticket', ValidationErrorCodes.SESSION_TIMEOUT);
+	}
+	const user = await ctx.services.users.findUniqueAssert(createUserID(BigInt(userId)));
+	AuthUtility.assertNonBotUser(ctx, user);
+	return user;
+}
+
+async function requireLegacyCredentials(ctx: ApiContext, userId: UserID): Promise<Array<WebAuthnCredential>> {
+	const legacyRpId = ctx.services.config.auth.passkeys.rpId;
+	const credentials = visibleWebAuthnCredentials(await ctx.services.users.listWebAuthnCredentials(userId)).filter(
+		(credential) => effectiveRpId(ctx, credential) === legacyRpId,
+	);
+	if (credentials.length === 0) {
+		throw new NoPasskeysRegisteredError();
+	}
+	return credentials;
+}
+
+function assertBridgeStartOrigin(ctx: ApiContext, origin: string | undefined): string {
+	if (!origin || !isPasskeyTargetOrigin(ctx, origin)) {
+		throw new InvalidApiOriginError();
+	}
+	return origin;
+}
+
+async function startPasskeyBridge(
+	ctx: ApiContext,
+	origin: string,
+	fields: Pick<PasskeyBridgeRecord, 'purpose' | 'runner' | 'nonce_hash' | 'user_id' | 'ticket'>,
+): Promise<PasskeyBridgeStartResponse> {
+	const ceremonyId = createSecret();
+	const createdAt = Date.now();
+	const ceremonyOrigin = fields.runner === 'page' ? passkeyLegacyOriginFor(origin) : origin;
+	await writeRecord(ctx, ceremonyId, {
+		...fields,
+		target_origin: origin,
+		ceremony_origin: ceremonyOrigin,
+		challenge: null,
+		credential_id: null,
+		cross_device: false,
+		completion_code_hash: null,
+		status: 'pending',
+		created_at: createdAt,
+		expires_at: createdAt + (fields.purpose === 'login_mfa' ? ms('5 minutes') : ms('10 minutes')),
+	});
+	return {
+		ceremony_id: ceremonyId,
+		bridge_url: fields.runner === 'page' ? `${ceremonyOrigin}${PASSKEY_BRIDGE_PATH}#${ceremonyId}` : null,
+	};
+}
+
+export async function startPasskeyBridgeLogin(
+	ctx: ApiContext,
+	origin: string | undefined,
+	data: PasskeyBridgeLoginStartRequest,
+): Promise<PasskeyBridgeStartResponse> {
+	const targetOrigin = assertBridgeStartOrigin(ctx, origin);
+	let userId: string | null = null;
+	if (data.purpose === 'login_mfa') {
+		const user = await requireMfaTicketUser(ctx, data.ticket!);
+		if (!(await resolveWebAuthnSecondFactor(ctx, user))) {
+			throw new MfaNotEnabledError();
+		}
+		await requireLegacyCredentials(ctx, user.id);
+		userId = user.id.toString();
+	}
+	return startPasskeyBridge(ctx, targetOrigin, {
+		purpose: data.purpose,
+		runner: data.runner,
+		nonce_hash: data.nonce_hash,
+		user_id: userId,
+		ticket: data.ticket ?? null,
+	});
+}
+
+export async function startPasskeyBridgeSudo(
+	ctx: ApiContext,
+	origin: string | undefined,
+	userId: UserID,
+	data: PasskeyBridgeSudoStartRequest,
+): Promise<PasskeyBridgeStartResponse> {
+	const targetOrigin = assertBridgeStartOrigin(ctx, origin);
+	await requireLegacyCredentials(ctx, userId);
+	return startPasskeyBridge(ctx, targetOrigin, {
+		purpose: 'sudo',
+		runner: data.runner,
+		nonce_hash: data.nonce_hash,
+		user_id: userId.toString(),
+		ticket: null,
+	});
+}
+
+export async function getPasskeyBridgeOptions(
+	ctx: ApiContext,
+	ceremonyId: string,
+	origin: string | undefined,
+): Promise<{options: PublicKeyCredentialRequestOptionsJSON}> {
+	return mutateRecord(ctx, ceremonyId, origin, async (record) => {
+		if (record.status !== 'pending') {
+			throw new UnknownPasskeyBridgeError();
+		}
+		const legacyRpId = ctx.services.config.auth.passkeys.rpId;
+		const userId = record.user_id === null ? undefined : createUserID(BigInt(record.user_id));
+		const options = await AuthMfa.generateWebAuthnAuthenticationOptions(ctx, {
+			selection: {
+				rpId: legacyRpId,
+				credentials: userId === undefined ? null : await requireLegacyCredentials(ctx, userId),
+			},
+			context: 'bridge',
+			userId,
+		});
+		if (record.challenge !== null) {
+			await AuthMfa.deleteWebAuthnChallenge(ctx, record.challenge);
+		}
+		await writeRecord(ctx, ceremonyId, {...record, challenge: options.challenge});
+		return {options};
+	});
+}
+
+function buildReturnUrl(record: PasskeyBridgeRecord, ceremonyId: string, completionCode: string): string {
+	return `${record.target_origin}${PASSKEY_BRIDGE_PATH}#${PASSKEY_BRIDGE_RETURN_FRAGMENT_KEY}=${ceremonyId}.${completionCode}`;
+}
+
+async function finishRecord(
+	ctx: ApiContext,
+	ceremonyId: string,
+	record: PasskeyBridgeRecord,
+): Promise<PasskeyBridgeFinishResponse> {
+	const completionCode = createSecret();
+	await writeRecord(ctx, ceremonyId, {...record, completion_code_hash: sha256Hex(completionCode)});
+	if (record.runner === 'native') {
+		return {return_url: null, completion_code: completionCode};
+	}
+	return {return_url: buildReturnUrl(record, ceremonyId, completionCode), completion_code: null};
+}
+
+export async function completePasskeyBridge(
+	ctx: ApiContext,
+	ceremonyId: string,
+	origin: string | undefined,
+	data: PasskeyBridgeCompleteRequest,
+): Promise<PasskeyBridgeFinishResponse> {
+	return mutateRecord(ctx, ceremonyId, origin, async (record) => {
+		if (record.status !== 'pending') {
+			throw new UnknownPasskeyBridgeError();
+		}
+		const {users} = ctx.services;
+		const credentialId = data.response.id;
+		const userId =
+			record.user_id === null
+				? await users.getUserIdByCredentialId(credentialId)
+				: createUserID(BigInt(record.user_id));
+		const credential = userId === null ? null : await users.getWebAuthnCredential(userId, credentialId);
+		if (
+			userId === null ||
+			record.challenge === null ||
+			credential === null ||
+			credential.supersededBy !== null ||
+			effectiveRpId(ctx, credential) !== ctx.services.config.auth.passkeys.rpId
+		) {
+			throw new PasskeyAuthenticationFailedError();
+		}
+		if (record.purpose === 'login_mfa') {
+			await requireMfaTicketUser(ctx, record.ticket!, record.user_id!);
+			await AuthLogin.consumeMfaAttempt(ctx, {userId: record.user_id!, ticket: record.ticket!, field: 'ticket'});
+		} else if (record.purpose === 'sudo') {
+			await AuthMfa.consumeSudoMfaAttempt(ctx, userId);
+		}
+		await AuthMfa.verifyWebAuthnAuthentication(ctx, userId, data.response, record.challenge, 'bridge', undefined, [
+			record.ceremony_origin,
+		]);
+		return finishRecord(ctx, ceremonyId, {
+			...record,
+			status: 'completed',
+			user_id: userId.toString(),
+			credential_id: credentialId,
+			cross_device: data.response.authenticatorAttachment === 'cross-platform',
+		});
+	});
+}
+
+export async function cancelPasskeyBridge(
+	ctx: ApiContext,
+	ceremonyId: string,
+	origin: string | undefined,
+): Promise<PasskeyBridgeFinishResponse> {
+	return mutateRecord(ctx, ceremonyId, origin, async (record) => {
+		if (record.status === 'completed') {
+			throw new UnknownPasskeyBridgeError();
+		}
+		return finishRecord(ctx, ceremonyId, {...record, status: 'cancelled'});
+	});
+}
+
+function assertRedeemable(
+	record: PasskeyBridgeRecord | null,
+	purposes: ReadonlyArray<PasskeyBridgePurpose>,
+	expectedUserId: UserID | null,
+): asserts record is PasskeyBridgeRecord {
+	if (
+		!record ||
+		!purposes.includes(record.purpose) ||
+		(expectedUserId !== null && record.user_id !== expectedUserId.toString()) ||
+		record.status === 'pending'
+	) {
+		throw new UnknownPasskeyBridgeError();
+	}
+}
+
+async function redeemPasskeyBridge(
+	ctx: ApiContext,
+	ceremonyId: string,
+	origin: string | undefined,
+	data: PasskeyBridgeRedeemRequest,
+	purposes: ReadonlyArray<PasskeyBridgePurpose>,
+	expectedUserId: UserID | null,
+): Promise<CompletedPasskeyBridge | null> {
+	const {cache} = ctx.services;
+	const key = passkeyBridgeKey(ceremonyId);
+	const record = await cache.get<PasskeyBridgeRecord>(key);
+	if (!record) {
+		throw new UnknownPasskeyBridgeError();
+	}
+	assertCeremonyOrigin(ctx, record, origin, record.target_origin);
+	assertRedeemable(record, purposes, expectedUserId);
+	if (!hashMatches(data.nonce, record.nonce_hash) || !hashMatches(data.completion_code, record.completion_code_hash)) {
+		await cache.delete(key);
+		throw new InvalidPasskeyBridgeNonceError();
+	}
+	const taken = await cache.getAndDelete<PasskeyBridgeRecord>(key);
+	assertRedeemable(taken, purposes, expectedUserId);
+	if (!hashMatches(data.nonce, taken.nonce_hash) || !hashMatches(data.completion_code, taken.completion_code_hash)) {
+		throw new InvalidPasskeyBridgeNonceError();
+	}
+	if (taken.status === 'cancelled') {
+		return null;
+	}
+	return {record: taken, userId: createUserID(BigInt(taken.user_id!))};
+}
+
+async function recordMigrationIfActive(
+	ctx: ApiContext,
+	origin: string | undefined,
+	completed: CompletedPasskeyBridge,
+	authSession: AuthSession | undefined,
+): Promise<void> {
+	if (!authSession || !(await isPasskeyMigrationActive(ctx, origin))) return;
+	await recordPendingPasskeyMigration(ctx, authSession, {
+		user_id: completed.userId.toString(),
+		credential_id: completed.record.credential_id!,
+		cross_device: completed.record.cross_device,
+	});
+}
+
+export async function redeemPasskeyBridgeLogin(
+	ctx: ApiContext,
+	ceremonyId: string,
+	origin: string | undefined,
+	data: PasskeyBridgeRedeemRequest,
+	request: Request,
+): Promise<PasskeyBridgeLoginRedeemResponse> {
+	const completed = await redeemPasskeyBridge(ctx, ceremonyId, origin, data, ['login', 'login_mfa'], null);
+	if (!completed) {
+		return {status: 'cancelled'};
+	}
+	let token: string;
+	let authSession: AuthSession;
+	let user: User;
+	if (completed.record.purpose === 'login_mfa') {
+		user = await requireMfaTicketUser(ctx, completed.record.ticket!, completed.record.user_id!);
+		if (!(await resolveWebAuthnSecondFactor(ctx, user))) {
+			throw new MfaNotEnabledError();
+		}
+		[token, authSession] = await AuthLogin.completeMfaLogin(ctx, user, completed.record.ticket!, request);
+	} else {
+		user = await ctx.services.users.findUniqueAssert(completed.userId);
+		[token, authSession] = await AuthLogin.createLoginSession(ctx, user, request);
+	}
+	await recordMigrationIfActive(ctx, origin, completed, authSession);
+	return {status: 'completed', token, user_id: user.id.toString(), user: mapUserToPartialResponse(user)};
+}
+
+export async function redeemPasskeyBridgeSudo(
+	ctx: ApiContext,
+	ceremonyId: string,
+	origin: string | undefined,
+	data: PasskeyBridgeRedeemRequest,
+	userId: UserID,
+	authSession: AuthSession | undefined,
+): Promise<PasskeyBridgeSudoRedeemResponse> {
+	const completed = await redeemPasskeyBridge(ctx, ceremonyId, origin, data, ['sudo'], userId);
+	if (!completed) {
+		return {status: 'cancelled'};
+	}
+	const sudoToken = await getSudoModeService().generateSudoToken(userId);
+	await recordMigrationIfActive(ctx, origin, completed, authSession);
+	return {status: 'completed', sudo_token: sudoToken};
+}
@@ -0,0 +1,166 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import type {ApiContext} from '@app/api/ApiContext';
+import * as AuthMfa from '@app/api/auth/AuthMfa';
+import {
+	effectiveRpId,
+	isPasskeyTargetOrigin,
+	visibleWebAuthnCredentials,
+} from '@app/api/auth/services/PasskeyRelyingParty';
+import type {UserID} from '@app/api/BrandedTypes';
+import type {AuthSession} from '@app/api/models/AuthSession';
+import type {WebAuthnCredential} from '@app/api/models/WebAuthnCredential';
+import {PASSKEY_MIGRATION_RP_ID} from '@fluxer/constants/src/PasskeyConstants';
+import {UnknownPasskeyMigrationError} from '@fluxer/errors/src/domains/auth/UnknownPasskeyMigrationError';
+import type {
+	PasskeyMigrationCompleteRequest,
+	PasskeyMigrationResponse,
+} from '@fluxer/schema/src/domains/auth/PasskeyMigrationSchemas';
+import type {PublicKeyCredentialCreationOptionsJSON} from '@simplewebauthn/server';
+import {seconds} from 'itty-time';
+
+const PASSKEY_MIGRATION_KEY_PREFIX = 'passkey_migration:';
+
+interface PendingPasskeyMigration {
+	user_id: string;
+	credential_id: string;
+	cross_device: boolean;
+}
+
+interface LivePasskeyMigration {
+	key: string;
+	pending: PendingPasskeyMigration;
+	credential: WebAuthnCredential;
+}
+
+function passkeyMigrationKey(authSession: AuthSession): string {
+	return `${PASSKEY_MIGRATION_KEY_PREFIX}${authSession.sessionIdHash.toString('base64url')}`;
+}
+
+function isLegacyVisibleCredential(ctx: ApiContext, credential: WebAuthnCredential): boolean {
+	return credential.supersededBy === null && effectiveRpId(ctx, credential) === ctx.services.config.auth.passkeys.rpId;
+}
+
+export async function recordPendingPasskeyMigration(
+	ctx: ApiContext,
+	authSession: AuthSession,
+	pending: PendingPasskeyMigration,
+): Promise<void> {
+	await ctx.services.cache.set(passkeyMigrationKey(authSession), pending, seconds('5 minutes'));
+}
+
+async function loadLivePasskeyMigration(
+	ctx: ApiContext,
+	userId: UserID,
+	authSession: AuthSession | undefined,
+): Promise<LivePasskeyMigration | null> {
+	if (!authSession) return null;
+	const {cache, users} = ctx.services;
+	const key = passkeyMigrationKey(authSession);
+	const pending = await cache.get<PendingPasskeyMigration>(key);
+	if (!pending) return null;
+	const credential =
+		pending.user_id === userId.toString() ? await users.getWebAuthnCredential(userId, pending.credential_id) : null;
+	if (credential === null || !isLegacyVisibleCredential(ctx, credential)) {
+		await cache.delete(key);
+		return null;
+	}
+	return {key, pending, credential};
+}
+
+async function requireLivePasskeyMigration(
+	ctx: ApiContext,
+	userId: UserID,
+	authSession: AuthSession | undefined,
+	origin: string | undefined,
+): Promise<LivePasskeyMigration> {
+	const live = isPasskeyTargetOrigin(ctx, origin) ? await loadLivePasskeyMigration(ctx, userId, authSession) : null;
+	if (!live) {
+		throw new UnknownPasskeyMigrationError();
+	}
+	return live;
+}
+
+async function takeLivePasskeyMigration(ctx: ApiContext, userId: UserID, key: string): Promise<WebAuthnCredential> {
+	const pending = await ctx.services.cache.getAndDelete<PendingPasskeyMigration>(key);
+	if (!pending || pending.user_id !== userId.toString()) {
+		throw new UnknownPasskeyMigrationError();
+	}
+	const credential = await ctx.services.users.getWebAuthnCredential(userId, pending.credential_id);
+	if (credential === null || !isLegacyVisibleCredential(ctx, credential)) {
+		throw new UnknownPasskeyMigrationError();
+	}
+	return credential;
+}
+
+function visibleTargetCredentials(ctx: ApiContext, credentials: Array<WebAuthnCredential>): Array<WebAuthnCredential> {
+	return visibleWebAuthnCredentials(credentials).filter(
+		(credential) => effectiveRpId(ctx, credential) === PASSKEY_MIGRATION_RP_ID,
+	);
+}
+
+export async function getPasskeyMigration(
+	ctx: ApiContext,
+	userId: UserID,
+	authSession: AuthSession | undefined,
+): Promise<PasskeyMigrationResponse> {
+	const live = await loadLivePasskeyMigration(ctx, userId, authSession);
+	if (!live) return {pending: null};
+	return {
+		pending: {
+			credential_id: live.credential.credentialId,
+			name: live.credential.name,
+			cross_device: live.pending.cross_device,
+		},
+	};
+}
+
+export async function getPasskeyMigrationRegistrationOptions(
+	ctx: ApiContext,
+	userId: UserID,
+	authSession: AuthSession | undefined,
+	origin: string | undefined,
+): Promise<PublicKeyCredentialCreationOptionsJSON> {
+	const live = await requireLivePasskeyMigration(ctx, userId, authSession, origin);
+	const credentials = await ctx.services.users.listWebAuthnCredentials(userId);
+	const options = await AuthMfa.createWebAuthnRegistrationOptions(ctx, userId, {
+		rpId: PASSKEY_MIGRATION_RP_ID,
+		context: 'migration_registration',
+		excludeCredentials: visibleTargetCredentials(ctx, credentials),
+	});
+	if (live.pending.cross_device) {
+		options.hints = ['hybrid', 'security-key'];
+	}
+	return options;
+}
+
+export async function completePasskeyMigration(
+	ctx: ApiContext,
+	userId: UserID,
+	authSession: AuthSession | undefined,
+	origin: string | undefined,
+	data: PasskeyMigrationCompleteRequest,
+): Promise<void> {
+	const {users} = ctx.services;
+	const live = await requireLivePasskeyMigration(ctx, userId, authSession, origin);
+	const verified = await AuthMfa.verifyWebAuthnRegistrationResponse(
+		ctx,
+		userId,
+		data.response,
+		data.challenge,
+		'migration_registration',
+		[origin!],
+	);
+	const legacy = await takeLivePasskeyMigration(ctx, userId, live.key);
+	await users.createWebAuthnCredential(
+		userId,
+		verified.credentialId,
+		verified.publicKey,
+		verified.counter,
+		verified.transports,
+		legacy.name,
+		AuthMfa.storedRpId(ctx, verified.rpId),
+	);
+	await users.setWebAuthnCredentialSupersededBy(userId, legacy.credentialId, verified.credentialId);
+	await AuthMfa.dispatchWebAuthnCredentialsUpdate(ctx, userId);
+}
@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import type {ApiContext} from '@app/api/ApiContext';
+import {getInstanceConfigRepository} from '@app/api/middleware/ServiceSingletons';
+import type {WebAuthnCredential} from '@app/api/models/WebAuthnCredential';
+import {PASSKEY_MIGRATION_RP_ID} from '@fluxer/constants/src/PasskeyConstants';
+
+const PASSKEY_TARGET_TO_LEGACY_ORIGIN: ReadonlyMap<string, string> = new Map([
+	['https://fluxer.com', 'https://web.fluxer.app'],
+	['https://canary.fluxer.com', 'https://web.canary.fluxer.app'],
+]);
+
+export interface CredentialRpSelection {
+	rpId: string;
+	credentials: Array<WebAuthnCredential>;
+}
+
+export function isPasskeyTargetOrigin(ctx: ApiContext, origin: string | null | undefined): boolean {
+	if (ctx.services.config.instance.selfHosted || !origin) return false;
+	return PASSKEY_TARGET_TO_LEGACY_ORIGIN.has(origin);
+}
+
+export function passkeyLegacyOriginFor(targetOrigin: string): string {
+	return PASSKEY_TARGET_TO_LEGACY_ORIGIN.get(targetOrigin)!;
+}
+
+export function effectiveRpId(ctx: ApiContext, credential: WebAuthnCredential): string {
+	return credential.rpId ?? ctx.services.config.auth.passkeys.rpId;
+}
+
+export function visibleWebAuthnCredentials(credentials: Array<WebAuthnCredential>): Array<WebAuthnCredential> {
+	return credentials.filter((credential) => credential.supersededBy === null);
+}
+
+export function originRpId(ctx: ApiContext, origin: string | null | undefined): string {
+	return isPasskeyTargetOrigin(ctx, origin) ? PASSKEY_MIGRATION_RP_ID : ctx.services.config.auth.passkeys.rpId;
+}
+
+export async function isPasskeyMigrationActive(ctx: ApiContext, origin: string | null | undefined): Promise<boolean> {
+	if (!isPasskeyTargetOrigin(ctx, origin)) return false;
+	const config = await getInstanceConfigRepository().getDomainMigrationConfig();
+	return config.enabled;
+}
+
+function credentialGroup(ctx: ApiContext, credentials: Array<WebAuthnCredential>, rpId: string): CredentialRpSelection {
+	return {rpId, credentials: credentials.filter((credential) => effectiveRpId(ctx, credential) === rpId)};
+}
+
+export function selectCredentialRp(
+	ctx: ApiContext,
+	origin: string | null | undefined,
+	credentials: Array<WebAuthnCredential>,
+): CredentialRpSelection {
+	const legacyRpId = ctx.services.config.auth.passkeys.rpId;
+	const visible = visibleWebAuthnCredentials(credentials);
+	if (isPasskeyTargetOrigin(ctx, origin)) {
+		const target = credentialGroup(ctx, visible, PASSKEY_MIGRATION_RP_ID);
+		return target.credentials.length > 0 ? target : credentialGroup(ctx, visible, legacyRpId);
+	}
+	const legacy = credentialGroup(ctx, credentials, legacyRpId);
+	return legacy.credentials.length > 0 ? legacy : credentialGroup(ctx, visible, PASSKEY_MIGRATION_RP_ID);
+}
@@ -0,0 +1,213 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import {createHash, randomBytes} from 'node:crypto';
+import {createAuthHarness, createTestAccount} from '@app/api/auth/tests/AuthTestUtils';
+import {createTestBotAccount} from '@app/api/bot/tests/BotTestUtils';
+import {getConfig} from '@app/api/Config';
+import type {ApiTestHarness} from '@app/api/test/ApiTestHarness';
+import {HTTP_STATUS} from '@app/api/test/TestConstants';
+import {createBuilder, createBuilderWithoutAuth} from '@app/api/test/TestRequestBuilder';
+import {APIErrorCodes} from '@fluxer/constants/src/ApiErrorCodes';
+import {SuspiciousActivityFlags} from '@fluxer/constants/src/UserConstants';
+import {
+	ORIGIN_HANDOFF_MAX_PAYLOAD_LENGTH,
+	type OriginHandoffCreateResponse,
+	type OriginHandoffRedeemResponse,
+} from '@fluxer/schema/src/domains/auth/OriginHandoffSchemas';
+import {afterAll, afterEach, beforeAll, beforeEach, describe, expect, it} from 'vitest';
+
+const CREATE_PATH = '/auth/origin-handoff';
+const REDEEM_PATH = '/auth/origin-handoff/redeem';
+const PAYLOAD = randomBytes(96).toString('base64url');
+
+function createNonce(): {nonce: string; nonceHash: string} {
+	const nonce = randomBytes(32).toString('base64url');
+	return {nonce, nonceHash: createHash('sha256').update(nonce).digest('hex')};
+}
+
+describe('Origin handoff', () => {
+	let harness: ApiTestHarness;
+	let webAppOrigin: string;
+
+	beforeAll(async () => {
+		harness = await createAuthHarness();
+		webAppOrigin = getConfig().endpoints.webAppOrigins[0];
+	});
+
+	beforeEach(async () => {
+		await harness.reset();
+	});
+
+	afterEach(() => {
+		getConfig().instance.selfHosted = false;
+		getConfig().endpoints.webAppOrigins = [webAppOrigin];
+	});
+
+	afterAll(async () => {
+		await harness?.shutdown();
+	});
+
+	async function createHandoff(token: string, nonceHash: string): Promise<string> {
+		const response = await createBuilder<OriginHandoffCreateResponse>(harness, token)
+			.post(CREATE_PATH)
+			.body({nonce_hash: nonceHash, payload: PAYLOAD})
+			.execute();
+		expect(response.handoff_id).toMatch(/^[A-Za-z0-9_-]{43}$/);
+		return response.handoff_id;
+	}
+
+	it('hands the payload over once to the origin that holds the nonce', async () => {
+		const account = await createTestAccount(harness);
+		const {nonce, nonceHash} = createNonce();
+		const handoffId = await createHandoff(account.token, nonceHash);
+
+		const redeemed = await createBuilderWithoutAuth<OriginHandoffRedeemResponse>(harness)
+			.post(REDEEM_PATH)
+			.header('origin', webAppOrigin)
+			.body({handoff_id: handoffId, nonce})
+			.execute();
+		expect(redeemed).toEqual({payload: PAYLOAD});
+
+		await createBuilderWithoutAuth(harness)
+			.post(REDEEM_PATH)
+			.header('origin', webAppOrigin)
+			.body({handoff_id: handoffId, nonce})
+			.expect(HTTP_STATUS.NOT_FOUND, APIErrorCodes.UNKNOWN_ORIGIN_HANDOFF)
+			.execute();
+	});
+
+	it('consumes the handoff when the nonce does not match', async () => {
+		const account = await createTestAccount(harness);
+		const {nonce, nonceHash} = createNonce();
+		const handoffId = await createHandoff(account.token, nonceHash);
+
+		await createBuilderWithoutAuth(harness)
+			.post(REDEEM_PATH)
+			.header('origin', webAppOrigin)
+			.body({handoff_id: handoffId, nonce: createNonce().nonce})
+			.expect(HTTP_STATUS.BAD_REQUEST, APIErrorCodes.INVALID_ORIGIN_HANDOFF_NONCE)
+			.execute();
+
+		await createBuilderWithoutAuth(harness)
+			.post(REDEEM_PATH)
+			.header('origin', webAppOrigin)
+			.body({handoff_id: handoffId, nonce})
+			.expect(HTTP_STATUS.NOT_FOUND, APIErrorCodes.UNKNOWN_ORIGIN_HANDOFF)
+			.execute();
+	});
+
+	it('answers an unknown handoff id with its own error code', async () => {
+		await createBuilderWithoutAuth(harness)
+			.post(REDEEM_PATH)
+			.header('origin', webAppOrigin)
+			.body({handoff_id: randomBytes(32).toString('base64url'), nonce: createNonce().nonce})
+			.expect(HTTP_STATUS.NOT_FOUND, APIErrorCodes.UNKNOWN_ORIGIN_HANDOFF)
+			.execute();
+	});
+
+	it('requires a logged-in user to create a handoff', async () => {
+		await createBuilderWithoutAuth(harness)
+			.post(CREATE_PATH)
+			.body({nonce_hash: createNonce().nonceHash, payload: PAYLOAD})
+			.expect(HTTP_STATUS.UNAUTHORIZED)
+			.execute();
+	});
+
+	it('refuses to create a handoff for an account flagged as suspicious', async () => {
+		const account = await createTestAccount(harness);
+		await createBuilderWithoutAuth(harness)
+			.post(`/test/users/${account.userId}/security-flags`)
+			.body({suspicious_activity_flags: SuspiciousActivityFlags.REQUIRE_VERIFIED_PHONE})
+			.execute();
+		await createBuilder(harness, account.token)
+			.post(CREATE_PATH)
+			.body({nonce_hash: createNonce().nonceHash, payload: PAYLOAD})
+			.expect(HTTP_STATUS.FORBIDDEN, APIErrorCodes.ACCOUNT_SUSPICIOUS_ACTIVITY)
+			.execute();
+	});
+
+	it('refuses a create body larger than the payload ceiling before parsing it', async () => {
+		const account = await createTestAccount(harness);
+		await createBuilder(harness, account.token)
+			.post(CREATE_PATH)
+			.body({nonce_hash: createNonce().nonceHash, payload: 'a'.repeat(ORIGIN_HANDOFF_MAX_PAYLOAD_LENGTH + 2048)})
+			.expect(HTTP_STATUS.BAD_REQUEST, APIErrorCodes.FILE_SIZE_TOO_LARGE)
+			.execute();
+	});
+
+	it('refuses to create a handoff for a bot', async () => {
+		const bot = await createTestBotAccount(harness);
+		await createBuilder(harness, `Bot ${bot.botToken}`)
+			.post(CREATE_PATH)
+			.body({nonce_hash: createNonce().nonceHash, payload: PAYLOAD})
+			.expect(HTTP_STATUS.FORBIDDEN)
+			.execute();
+	});
+
+	it.each([
+		{name: 'an uppercase nonce hash', body: {nonce_hash: 'A'.repeat(64), payload: PAYLOAD}},
+		{name: 'a short nonce hash', body: {nonce_hash: 'a'.repeat(63), payload: PAYLOAD}},
+		{name: 'a payload outside base64url', body: {nonce_hash: 'a'.repeat(64), payload: 'not+base64/url='}},
+		{name: 'an empty payload', body: {nonce_hash: 'a'.repeat(64), payload: ''}},
+	])('rejects $name', async ({body}) => {
+		const account = await createTestAccount(harness);
+		await createBuilder(harness, account.token)
+			.post(CREATE_PATH)
+			.body(body)
+			.expect(HTTP_STATUS.BAD_REQUEST, APIErrorCodes.INVALID_FORM_BODY)
+			.execute();
+	});
+
+	it('refuses a redeem from an origin outside the first-party web origins', async () => {
+		const account = await createTestAccount(harness);
+		const {nonce, nonceHash} = createNonce();
+		const handoffId = await createHandoff(account.token, nonceHash);
+
+		await createBuilderWithoutAuth(harness)
+			.post(REDEEM_PATH)
+			.header('origin', 'https://evil.example')
+			.body({handoff_id: handoffId, nonce})
+			.expect(HTTP_STATUS.FORBIDDEN, APIErrorCodes.INVALID_API_ORIGIN)
+			.execute();
+
+		await createBuilderWithoutAuth(harness)
+			.post(REDEEM_PATH)
+			.body({handoff_id: handoffId, nonce})
+			.expect(HTTP_STATUS.FORBIDDEN, APIErrorCodes.INVALID_API_ORIGIN)
+			.execute();
+
+		const redeemed = await createBuilderWithoutAuth<OriginHandoffRedeemResponse>(harness)
+			.post(REDEEM_PATH)
+			.header('origin', webAppOrigin)
+			.body({handoff_id: handoffId, nonce})
+			.execute();
+		expect(redeemed.payload).toBe(PAYLOAD);
+	});
+
+	it('accepts a redeem from a configured web app origin alias', async () => {
+		getConfig().endpoints.webAppOrigins = [webAppOrigin, 'https://fluxer.com'];
+		const account = await createTestAccount(harness);
+		const {nonce, nonceHash} = createNonce();
+		const handoffId = await createHandoff(account.token, nonceHash);
+
+		const redeemed = await createBuilderWithoutAuth<OriginHandoffRedeemResponse>(harness)
+			.post(REDEEM_PATH)
+			.header('origin', 'https://fluxer.com')
+			.body({handoff_id: handoffId, nonce})
+			.execute();
+		expect(redeemed.payload).toBe(PAYLOAD);
+	});
+
+	it('skips the origin check on a self-hosted instance', async () => {
+		getConfig().instance.selfHosted = true;
+		const account = await createTestAccount(harness);
+		const {nonce, nonceHash} = createNonce();
+		const handoffId = await createHandoff(account.token, nonceHash);
+
+		const redeemed = await createBuilderWithoutAuth<OriginHandoffRedeemResponse>(harness)
+			.post(REDEEM_PATH)
+			.body({handoff_id: handoffId, nonce})
+			.execute();
+		expect(redeemed.payload).toBe(PAYLOAD);
+	});
+});
@@ -0,0 +1,391 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import {createHash} from 'node:crypto';
+import {
+	createAuthHarness,
+	createTestAccount,
+	type LoginMfaResponse,
+	loginUser,
+	type TestAccount,
+} from '@app/api/auth/tests/AuthTestUtils';
+import {
+	type BridgeNonce,
+	createBridgeNonce,
+	LEGACY_ORIGIN,
+	LEGACY_RP_ID,
+	registerPasskey,
+	runNativeSudoBridge,
+	setDomainMigration,
+	TARGET_ORIGIN,
+} from '@app/api/auth/tests/PasskeyTestUtils';
+import {
+	createAuthenticationResponse,
+	createTotpSecret,
+	createWebAuthnDevice,
+	generateTotpCode,
+	setWebAuthnTwoFactor,
+	type WebAuthnAuthenticationOptions,
+	type WebAuthnDevice,
+} from '@app/api/auth/tests/WebAuthnTestUtils';
+import {getConfig} from '@app/api/Config';
+import {getCacheService} from '@app/api/middleware/ServiceSingletons';
+import type {ApiTestHarness} from '@app/api/test/ApiTestHarness';
+import {HTTP_STATUS} from '@app/api/test/TestConstants';
+import {createBuilder, createBuilderWithoutAuth} from '@app/api/test/TestRequestBuilder';
+import {APIErrorCodes} from '@fluxer/constants/src/ApiErrorCodes';
+import type {
+	PasskeyBridgeFinishResponse,
+	PasskeyBridgeLoginRedeemResponse,
+	PasskeyBridgeStartResponse,
+	PasskeyBridgeSudoRedeemResponse,
+} from '@fluxer/schema/src/domains/auth/PasskeyBridgeSchemas';
+import {afterAll, afterEach, beforeAll, beforeEach, describe, expect, it} from 'vitest';
+
+const SUDO_MODE_HEADER = 'X-Fluxer-Sudo-Mode-JWT';
+
+interface StartedBridge {
+	ceremonyId: string;
+	bridgeUrl: string | null;
+	nonce: BridgeNonce;
+}
+
+describe('Passkey bridge', () => {
+	let harness: ApiTestHarness;
+
+	beforeAll(async () => {
+		harness = await createAuthHarness();
+	});
+
+	beforeEach(async () => {
+		await harness.reset();
+		await setDomainMigration(true);
+	});
+
+	afterEach(() => {
+		getConfig().instance.selfHosted = false;
+	});
+
+	afterAll(async () => {
+		await harness?.shutdown();
+	});
+
+	async function createLegacyAccount(): Promise<{account: TestAccount; device: WebAuthnDevice}> {
+		const account = await createTestAccount(harness);
+		const device = createWebAuthnDevice();
+		await registerPasskey(harness, account.token, device, {password: account.password}, 'Old');
+		return {account, device};
+	}
+
+	async function startLogin(body: Record<string, unknown> = {}, origin = TARGET_ORIGIN): Promise<StartedBridge> {
+		const nonce = createBridgeNonce();
+		const start = await createBuilderWithoutAuth<PasskeyBridgeStartResponse>(harness)
+			.post('/auth/passkey-bridge')
+			.header('origin', origin)
+			.body({purpose: 'login', runner: 'page', nonce_hash: nonce.nonceHash, ...body})
+			.execute();
+		return {ceremonyId: start.ceremony_id, bridgeUrl: start.bridge_url, nonce};
+	}
+
+	async function startSudo(token: string, runner: 'page' | 'native' = 'page'): Promise<StartedBridge> {
+		const nonce = createBridgeNonce();
+		const start = await createBuilder<PasskeyBridgeStartResponse>(harness, token)
+			.post('/users/@me/passkey-bridge')
+			.header('origin', TARGET_ORIGIN)
+			.body({runner, nonce_hash: nonce.nonceHash})
+			.execute();
+		return {ceremonyId: start.ceremony_id, bridgeUrl: start.bridge_url, nonce};
+	}
+
+	async function fetchOptions(ceremonyId: string, origin = LEGACY_ORIGIN): Promise<WebAuthnAuthenticationOptions> {
+		const {options} = await createBuilderWithoutAuth<{options: WebAuthnAuthenticationOptions}>(harness)
+			.post(`/auth/passkey-bridge/${ceremonyId}/options`)
+			.header('origin', origin)
+			.execute();
+		return options;
+	}
+
+	async function complete(
+		ceremonyId: string,
+		device: WebAuthnDevice,
+		origin = LEGACY_ORIGIN,
+	): Promise<PasskeyBridgeFinishResponse> {
+		const options = await fetchOptions(ceremonyId, origin);
+		return createBuilderWithoutAuth<PasskeyBridgeFinishResponse>(harness)
+			.post(`/auth/passkey-bridge/${ceremonyId}/complete`)
+			.header('origin', origin)
+			.body({response: createAuthenticationResponse(device, options)})
+			.execute();
+	}
+
+	function completionCodeFrom(finish: PasskeyBridgeFinishResponse, ceremonyId: string): string {
+		const url = new URL(finish.return_url!);
+		const [id, code] = url.hash.slice('#passkey-bridge='.length).split('.');
+		expect(id).toBe(ceremonyId);
+		return code;
+	}
+
+	function redeemLogin(ceremonyId: string, nonce: string, completionCode: string) {
+		return createBuilderWithoutAuth<PasskeyBridgeLoginRedeemResponse>(harness)
+			.post(`/auth/passkey-bridge/${ceremonyId}/redeem`)
+			.header('origin', TARGET_ORIGIN)
+			.body({nonce, completion_code: completionCode});
+	}
+
+	it('refuses to start outside the new origin and on a self-hosted instance, whatever the switch', async () => {
+		const nonce = createBridgeNonce();
+		const body = {purpose: 'login', runner: 'native', nonce_hash: nonce.nonceHash};
+		for (const origin of [LEGACY_ORIGIN, 'https://evil.example']) {
+			await createBuilderWithoutAuth(harness)
+				.post('/auth/passkey-bridge')
+				.header('origin', origin)
+				.body(body)
+				.expect(HTTP_STATUS.FORBIDDEN, APIErrorCodes.INVALID_API_ORIGIN)
+				.execute();
+		}
+		await createBuilderWithoutAuth(harness)
+			.post('/auth/passkey-bridge')
+			.body(body)
+			.expect(HTTP_STATUS.FORBIDDEN, APIErrorCodes.INVALID_API_ORIGIN)
+			.execute();
+		getConfig().instance.selfHosted = true;
+		await createBuilderWithoutAuth(harness)
+			.post('/auth/passkey-bridge')
+			.header('origin', TARGET_ORIGIN)
+			.body(body)
+			.expect(HTTP_STATUS.FORBIDDEN, APIErrorCodes.INVALID_API_ORIGIN)
+			.execute();
+		getConfig().instance.selfHosted = false;
+		await setDomainMigration(false);
+		await createBuilderWithoutAuth(harness)
+			.post('/auth/passkey-bridge')
+			.header('origin', TARGET_ORIGIN)
+			.body(body)
+			.expect(HTTP_STATUS.OK)
+			.execute();
+	});
+
+	it('runs the ceremony only on the paired origin and keeps going when the switch goes off', async () => {
+		const {device} = await createLegacyAccount();
+		const started = await startLogin();
+		expect(started.bridgeUrl).toBe(`${LEGACY_ORIGIN}/passkey-bridge#${started.ceremonyId}`);
+		await createBuilderWithoutAuth(harness)
+			.post(`/auth/passkey-bridge/${started.ceremonyId}/options`)
+			.header('origin', TARGET_ORIGIN)
+			.expect(HTTP_STATUS.FORBIDDEN, APIErrorCodes.INVALID_API_ORIGIN)
+			.execute();
+		const options = await fetchOptions(started.ceremonyId);
+		expect(options.rpId).toBe(LEGACY_RP_ID);
+		expect(options.allowCredentials).toBeUndefined();
+		expect(options.userVerification).toBe('required');
+		await setDomainMigration(false);
+		await createBuilderWithoutAuth(harness)
+			.post(`/auth/passkey-bridge/${started.ceremonyId}/complete`)
+			.header('origin', LEGACY_ORIGIN)
+			.body({response: createAuthenticationResponse(device, options)})
+			.expect(HTTP_STATUS.OK)
+			.execute();
+	});
+
+	it('signs in through a page ceremony and always returns to the bridge page', async () => {
+		const {account, device} = await createLegacyAccount();
+		const started = await startLogin({
+			return_path: '/api/v1/oauth2/authorize?prompt=none&redirect_uri=https://evil.example/cb',
+		});
+		const finish = await complete(started.ceremonyId, device);
+		expect(finish.completion_code).toBeNull();
+		const returnUrl = new URL(finish.return_url!);
+		expect(`${returnUrl.origin}${returnUrl.pathname}${returnUrl.search}`).toBe(`${TARGET_ORIGIN}/passkey-bridge`);
+		const code = completionCodeFrom(finish, started.ceremonyId);
+		const redeemed = await redeemLogin(started.ceremonyId, started.nonce.nonce, code).execute();
+		expect(redeemed.status).toBe('completed');
+		if (redeemed.status !== 'completed') return;
+		expect(redeemed.user_id).toBe(account.userId);
+		const me = await createBuilder<{id: string}>(harness, redeemed.token).get('/users/@me').execute();
+		expect(me.id).toBe(account.userId);
+		await redeemLogin(started.ceremonyId, started.nonce.nonce, code)
+			.expect(HTTP_STATUS.NOT_FOUND, APIErrorCodes.UNKNOWN_PASSKEY_BRIDGE)
+			.execute();
+	});
+
+	it('needs both the nonce and the completion code', async () => {
+		const {device} = await createLegacyAccount();
+		const started = await startLogin();
+		const code = completionCodeFrom(await complete(started.ceremonyId, device), started.ceremonyId);
+		const attacker = createBridgeNonce();
+		await redeemLogin(started.ceremonyId, attacker.nonce, code)
+			.expect(HTTP_STATUS.BAD_REQUEST, APIErrorCodes.INVALID_PASSKEY_BRIDGE_NONCE)
+			.execute();
+		await redeemLogin(started.ceremonyId, started.nonce.nonce, code)
+			.expect(HTTP_STATUS.NOT_FOUND, APIErrorCodes.UNKNOWN_PASSKEY_BRIDGE)
+			.execute();
+
+		const second = await startLogin();
+		completionCodeFrom(await complete(second.ceremonyId, device), second.ceremonyId);
+		await redeemLogin(second.ceremonyId, second.nonce.nonce, 'A'.repeat(43))
+			.expect(HTTP_STATUS.BAD_REQUEST, APIErrorCodes.INVALID_PASSKEY_BRIDGE_NONCE)
+			.execute();
+		await redeemLogin(second.ceremonyId, second.nonce.nonce, 'A'.repeat(43))
+			.expect(HTTP_STATUS.NOT_FOUND, APIErrorCodes.UNKNOWN_PASSKEY_BRIDGE)
+			.execute();
+	});
+
+	it('keeps a pending ceremony when redeemed early or verification fails', async () => {
+		const {account, device} = await createLegacyAccount();
+		const target = createWebAuthnDevice();
+		await registerPasskey(harness, account.token, target, {password: account.password}, 'New', TARGET_ORIGIN);
+		const started = await startLogin();
+		await redeemLogin(started.ceremonyId, started.nonce.nonce, 'A'.repeat(43))
+			.expect(HTTP_STATUS.NOT_FOUND, APIErrorCodes.UNKNOWN_PASSKEY_BRIDGE)
+			.execute();
+		const options = await fetchOptions(started.ceremonyId);
+		await createBuilderWithoutAuth(harness)
+			.post(`/auth/passkey-bridge/${started.ceremonyId}/complete`)
+			.header('origin', LEGACY_ORIGIN)
+			.body({response: createAuthenticationResponse(target, options)})
+			.expect(HTTP_STATUS.UNAUTHORIZED, APIErrorCodes.PASSKEY_AUTHENTICATION_FAILED)
+			.execute();
+		const code = completionCodeFrom(await complete(started.ceremonyId, device), started.ceremonyId);
+		const redeemed = await redeemLogin(started.ceremonyId, started.nonce.nonce, code).execute();
+		expect(redeemed.status).toBe('completed');
+	});
+
+	it('never lets a bridge challenge through the normal endpoints', async () => {
+		const {device} = await createLegacyAccount();
+		const started = await startLogin();
+		const options = await fetchOptions(started.ceremonyId);
+		await createBuilderWithoutAuth(harness)
+			.post('/auth/webauthn/authenticate')
+			.header('origin', LEGACY_ORIGIN)
+			.body({response: createAuthenticationResponse(device, options), challenge: options.challenge})
+			.expect(HTTP_STATUS.UNAUTHORIZED, APIErrorCodes.PASSKEY_AUTHENTICATION_FAILED)
+			.execute();
+	});
+
+	it('reports a cancelled ceremony and refuses to cancel a completed one', async () => {
+		const {device} = await createLegacyAccount();
+		const started = await startLogin();
+		const cancelled = await createBuilderWithoutAuth<PasskeyBridgeFinishResponse>(harness)
+			.post(`/auth/passkey-bridge/${started.ceremonyId}/cancel`)
+			.header('origin', LEGACY_ORIGIN)
+			.execute();
+		const code = completionCodeFrom(cancelled, started.ceremonyId);
+		expect(await redeemLogin(started.ceremonyId, started.nonce.nonce, code).execute()).toEqual({status: 'cancelled'});
+
+		const second = await startLogin();
+		await complete(second.ceremonyId, device);
+		await createBuilderWithoutAuth(harness)
+			.post(`/auth/passkey-bridge/${second.ceremonyId}/cancel`)
+			.header('origin', LEGACY_ORIGIN)
+			.expect(HTTP_STATUS.NOT_FOUND, APIErrorCodes.UNKNOWN_PASSKEY_BRIDGE)
+			.execute();
+	});
+
+	it('completes two-factor sign in for the ticket holder', async () => {
+		const account = await createTestAccount(harness);
+		const device = createWebAuthnDevice();
+		const secret = createTotpSecret();
+		await createBuilder(harness, account.token)
+			.post('/users/@me/mfa/totp/enable')
+			.body({secret, code: generateTotpCode(secret), password: account.password})
+			.execute();
+		await registerPasskey(
+			harness,
+			account.token,
+			device,
+			{mfa_method: 'totp', mfa_code: generateTotpCode(secret)},
+			'Old',
+		);
+		await setWebAuthnTwoFactor(harness, account.token, true, {mfa_method: 'totp', mfa_code: generateTotpCode(secret)});
+		const login = (await loginUser(harness, {email: account.email, password: account.password})) as LoginMfaResponse;
+		const started = await startLogin({purpose: 'login_mfa', ticket: login.ticket});
+		const options = await fetchOptions(started.ceremonyId);
+		expect(options.allowCredentials?.map((cred) => cred.id)).toEqual([device.credentialId.toString('base64url')]);
+		expect(options.userVerification).toBe('discouraged');
+		const code = completionCodeFrom(await complete(started.ceremonyId, device), started.ceremonyId);
+		const redeemed = await redeemLogin(started.ceremonyId, started.nonce.nonce, code).execute();
+		expect(redeemed.status).toBe('completed');
+		await createBuilderWithoutAuth(harness)
+			.post('/auth/login/mfa/totp')
+			.body({code: generateTotpCode(secret), ticket: login.ticket})
+			.expect(HTTP_STATUS.BAD_REQUEST)
+			.execute();
+	});
+
+	it('issues a sudo token that passes a sudo-protected route', async () => {
+		const {account, device} = await createLegacyAccount();
+		const credentialId = device.credentialId.toString('base64url');
+		await createBuilder(harness, account.token)
+			.patch(`/users/@me/mfa/webauthn/credentials/${credentialId}`)
+			.body({name: 'Renamed'})
+			.expect(HTTP_STATUS.FORBIDDEN)
+			.execute();
+		const redeemed = await runNativeSudoBridge(harness, account.token, device);
+		expect(redeemed.status).toBe('completed');
+		if (redeemed.status !== 'completed') return;
+		await createBuilder(harness, account.token)
+			.patch(`/users/@me/mfa/webauthn/credentials/${credentialId}`)
+			.header(SUDO_MODE_HEADER, redeemed.sudo_token)
+			.body({name: 'Renamed'})
+			.expect(HTTP_STATUS.NO_CONTENT)
+			.execute();
+	});
+
+	it('returns sudo page ceremonies to the bridge page on the new origin', async () => {
+		const {account, device} = await createLegacyAccount();
+		const started = await startSudo(account.token);
+		const finish = await complete(started.ceremonyId, device);
+		const returnUrl = new URL(finish.return_url!);
+		expect(`${returnUrl.origin}${returnUrl.pathname}`).toBe(`${TARGET_ORIGIN}/passkey-bridge`);
+		const code = completionCodeFrom(finish, started.ceremonyId);
+		const redeemed = await createBuilder<PasskeyBridgeSudoRedeemResponse>(harness, account.token)
+			.post(`/users/@me/passkey-bridge/${started.ceremonyId}/redeem`)
+			.header('origin', TARGET_ORIGIN)
+			.body({nonce: started.nonce.nonce, completion_code: code})
+			.execute();
+		expect(redeemed.status).toBe('completed');
+	});
+
+	it('does not consume a ceremony redeemed on the wrong route or by another user', async () => {
+		const {account, device} = await createLegacyAccount();
+		const other = await createTestAccount(harness);
+		const started = await startSudo(account.token, 'native');
+		const options = await fetchOptions(started.ceremonyId, TARGET_ORIGIN);
+		const finish = await createBuilderWithoutAuth<PasskeyBridgeFinishResponse>(harness)
+			.post(`/auth/passkey-bridge/${started.ceremonyId}/complete`)
+			.header('origin', TARGET_ORIGIN)
+			.body({response: createAuthenticationResponse(device, options)})
+			.execute();
+		const body = {nonce: started.nonce.nonce, completion_code: finish.completion_code};
+		await redeemLogin(started.ceremonyId, body.nonce, body.completion_code!)
+			.expect(HTTP_STATUS.NOT_FOUND, APIErrorCodes.UNKNOWN_PASSKEY_BRIDGE)
+			.execute();
+		await createBuilder(harness, other.token)
+			.post(`/users/@me/passkey-bridge/${started.ceremonyId}/redeem`)
+			.header('origin', TARGET_ORIGIN)
+			.body(body)
+			.expect(HTTP_STATUS.NOT_FOUND, APIErrorCodes.UNKNOWN_PASSKEY_BRIDGE)
+			.execute();
+		const redeemed = await createBuilder<PasskeyBridgeSudoRedeemResponse>(harness, account.token)
+			.post(`/users/@me/passkey-bridge/${started.ceremonyId}/redeem`)
+			.header('origin', TARGET_ORIGIN)
+			.body(body)
+			.execute();
+		expect(redeemed.status).toBe('completed');
+	});
+
+	it('always stores the ceremony with an expiry', async () => {
+		const {device} = await createLegacyAccount();
+		const started = await startLogin();
+		const key = `passkey_bridge:${createHash('sha256').update(started.ceremonyId).digest('hex')}`;
+		const cache = getCacheService();
+		const ttls = [await cache.ttl(key)];
+		await fetchOptions(started.ceremonyId);
+		ttls.push(await cache.ttl(key));
+		await complete(started.ceremonyId, device);
+		ttls.push(await cache.ttl(key));
+		for (const ttl of ttls) {
+			expect(ttl).toBeGreaterThan(0);
+			expect(ttl).toBeLessThanOrEqual(600);
+		}
+	});
+});
@@ -0,0 +1,260 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import {createAuthHarness, createTestAccount, type TestAccount} from '@app/api/auth/tests/AuthTestUtils';
+import {
+	LEGACY_RP_ID,
+	listPasskeys,
+	registerPasskey,
+	runNativeSudoBridge,
+	setDomainMigration,
+	TARGET_ORIGIN,
+	TARGET_RP_ID,
+} from '@app/api/auth/tests/PasskeyTestUtils';
+import {
+	createAuthenticationResponse,
+	createRegistrationResponse,
+	createWebAuthnDevice,
+	type WebAuthnAuthenticationOptions,
+	type WebAuthnDevice,
+	type WebAuthnRegistrationOptions,
+} from '@app/api/auth/tests/WebAuthnTestUtils';
+import {createUserID} from '@app/api/BrandedTypes';
+import {getUserRepository} from '@app/api/middleware/ServiceSingletons';
+import type {ApiTestHarness} from '@app/api/test/ApiTestHarness';
+import {HTTP_STATUS} from '@app/api/test/TestConstants';
+import {createBuilder, createBuilderWithoutAuth} from '@app/api/test/TestRequestBuilder';
+import {APIErrorCodes} from '@fluxer/constants/src/ApiErrorCodes';
+import type {PasskeyMigrationResponse} from '@fluxer/schema/src/domains/auth/PasskeyMigrationSchemas';
+import {afterAll, beforeAll, beforeEach, describe, expect, it} from 'vitest';
+
+const MIGRATION_PATH = '/users/@me/mfa/webauthn/migration';
+const MIGRATION_OPTIONS_PATH = '/users/@me/mfa/webauthn/migration/registration-options';
+
+function credentialIdOf(device: WebAuthnDevice): string {
+	return device.credentialId.toString('base64url');
+}
+
+interface RpcSessionResponse {
+	data: {webauthn_credentials: Array<{id: string; rp_id: string}>};
+}
+
+describe('Passkey migration', () => {
+	let harness: ApiTestHarness;
+
+	beforeAll(async () => {
+		harness = await createAuthHarness();
+	});
+
+	beforeEach(async () => {
+		await harness.reset();
+	});
+
+	afterAll(async () => {
+		await harness?.shutdown();
+	});
+
+	async function createAssignedAccount(): Promise<{account: TestAccount; legacy: WebAuthnDevice}> {
+		const account = await createTestAccount(harness);
+		const legacy = createWebAuthnDevice();
+		await registerPasskey(harness, account.token, legacy, {password: account.password}, 'Laptop');
+		await setDomainMigration(true, [account.userId]);
+		return {account, legacy};
+	}
+
+	async function getPending(token: string): Promise<PasskeyMigrationResponse['pending']> {
+		const response = await createBuilder<PasskeyMigrationResponse>(harness, token).get(MIGRATION_PATH).execute();
+		return response.pending;
+	}
+
+	async function migrationOptions(token: string): Promise<WebAuthnRegistrationOptions> {
+		return createBuilder<WebAuthnRegistrationOptions>(harness, token)
+			.post(MIGRATION_OPTIONS_PATH)
+			.header('origin', TARGET_ORIGIN)
+			.execute();
+	}
+
+	function completeMigration(token: string, device: WebAuthnDevice, options: WebAuthnRegistrationOptions) {
+		return createBuilder(harness, token)
+			.post(MIGRATION_PATH)
+			.header('origin', TARGET_ORIGIN)
+			.body({response: createRegistrationResponse(device, options, 'Laptop'), challenge: options.challenge});
+	}
+
+	async function migrate(account: TestAccount, legacy: WebAuthnDevice): Promise<WebAuthnDevice> {
+		await runNativeSudoBridge(harness, account.token, legacy);
+		const target = createWebAuthnDevice();
+		await completeMigration(account.token, target, await migrationOptions(account.token))
+			.expect(HTTP_STATUS.NO_CONTENT)
+			.execute();
+		return target;
+	}
+
+	async function discoverableLogin(device: WebAuthnDevice, origin?: string, status: number = HTTP_STATUS.OK) {
+		const optionsBuilder = createBuilderWithoutAuth<WebAuthnAuthenticationOptions>(harness)
+			.post('/auth/webauthn/authentication-options')
+			.body(null);
+		if (origin) optionsBuilder.header('origin', origin);
+		const options = await optionsBuilder.execute();
+		const builder = createBuilderWithoutAuth(harness)
+			.post('/auth/webauthn/authenticate')
+			.body({response: createAuthenticationResponse(device, options), challenge: options.challenge})
+			.expect(status);
+		if (origin) builder.header('origin', origin);
+		await builder.execute();
+	}
+
+	it('records a pending update for any account on the new origin while the switch is on', async () => {
+		const unassigned = await createTestAccount(harness);
+		const unassignedDevice = createWebAuthnDevice();
+		await registerPasskey(harness, unassigned.token, unassignedDevice, {password: unassigned.password}, 'Laptop');
+		await setDomainMigration(false);
+		expect((await runNativeSudoBridge(harness, unassigned.token, unassignedDevice)).status).toBe('completed');
+		expect(await getPending(unassigned.token)).toBeNull();
+
+		await setDomainMigration(true);
+		expect((await runNativeSudoBridge(harness, unassigned.token, unassignedDevice)).status).toBe('completed');
+		expect(await getPending(unassigned.token)).toEqual({
+			credential_id: credentialIdOf(unassignedDevice),
+			name: 'Laptop',
+			cross_device: false,
+		});
+	});
+
+	it('needs a pending update and the new origin for registration options', async () => {
+		const {account, legacy} = await createAssignedAccount();
+		await createBuilder(harness, account.token)
+			.post(MIGRATION_OPTIONS_PATH)
+			.header('origin', TARGET_ORIGIN)
+			.expect(HTTP_STATUS.NOT_FOUND, APIErrorCodes.UNKNOWN_PASSKEY_MIGRATION)
+			.execute();
+		await runNativeSudoBridge(harness, account.token, legacy);
+		await createBuilder(harness, account.token)
+			.post(MIGRATION_OPTIONS_PATH)
+			.expect(HTTP_STATUS.NOT_FOUND, APIErrorCodes.UNKNOWN_PASSKEY_MIGRATION)
+			.execute();
+		const options = await migrationOptions(account.token);
+		expect(options.rp.id).toBe(TARGET_RP_ID);
+	});
+
+	it('replaces the passkey under the same name and hides the old one', async () => {
+		const {account, legacy} = await createAssignedAccount();
+		const target = await migrate(account, legacy);
+		const credentials = await listPasskeys(harness, account.token);
+		expect(credentials).toEqual([
+			expect.objectContaining({id: credentialIdOf(target), name: 'Laptop', rp_id: TARGET_RP_ID}),
+		]);
+		const old = await getUserRepository().getWebAuthnCredential(
+			createUserID(BigInt(account.userId)),
+			credentialIdOf(legacy),
+		);
+		expect(old?.supersededBy).toBe(credentialIdOf(target));
+		expect(await getPending(account.token)).toBeNull();
+		const ready = await createBuilder<RpcSessionResponse>(harness, '')
+			.post('/test/rpc-session-init')
+			.body({type: 'session', token: account.token, version: 1, ip: '127.0.0.1'})
+			.execute();
+		expect(ready.data.webauthn_credentials.map(({id, rp_id}) => ({id, rp_id}))).toEqual([
+			{id: credentialIdOf(target), rp_id: TARGET_RP_ID},
+		]);
+	});
+
+	it('keeps the old passkey working off the new origin', async () => {
+		const {account, legacy} = await createAssignedAccount();
+		const target = await migrate(account, legacy);
+		await discoverableLogin(legacy);
+		await discoverableLogin(legacy, TARGET_ORIGIN, HTTP_STATUS.UNAUTHORIZED);
+		await discoverableLogin(target, TARGET_ORIGIN);
+		await createBuilder(harness, account.token)
+			.patch(`/users/@me/mfa/webauthn/credentials/${credentialIdOf(legacy)}`)
+			.body({name: 'Renamed', password: account.password})
+			.expect(HTTP_STATUS.NOT_FOUND, APIErrorCodes.UNKNOWN_WEBAUTHN_CREDENTIAL)
+			.execute();
+		const sudoOptions = await createBuilder<WebAuthnAuthenticationOptions>(harness, account.token)
+			.post('/users/@me/sudo/webauthn/authentication-options')
+			.body(null)
+			.execute();
+		expect(sudoOptions.rpId).toBe(LEGACY_RP_ID);
+		expect(sudoOptions.allowCredentials?.map((cred) => cred.id)).toEqual([credentialIdOf(legacy)]);
+	});
+
+	it('removes the old passkey together with its replacement', async () => {
+		const {account, legacy} = await createAssignedAccount();
+		const target = await migrate(account, legacy);
+		await createBuilder(harness, account.token)
+			.delete(`/users/@me/mfa/webauthn/credentials/${credentialIdOf(target)}`)
+			.body({password: account.password})
+			.expect(HTTP_STATUS.NO_CONTENT)
+			.execute();
+		expect(await getUserRepository().listWebAuthnCredentials(createUserID(BigInt(account.userId)))).toEqual([]);
+		await discoverableLogin(legacy, undefined, HTTP_STATUS.UNAUTHORIZED);
+	});
+
+	it('removes every remaining superseded passkey with the last visible one', async () => {
+		const account = await createTestAccount(harness);
+		const orphan = createWebAuthnDevice();
+		const visible = createWebAuthnDevice();
+		await registerPasskey(harness, account.token, orphan, {password: account.password}, 'Orphan');
+		await registerPasskey(harness, account.token, visible, {password: account.password}, 'Visible');
+		const userId = createUserID(BigInt(account.userId));
+		await getUserRepository().setWebAuthnCredentialSupersededBy(userId, credentialIdOf(orphan), 'gone');
+		await createBuilder(harness, account.token)
+			.delete(`/users/@me/mfa/webauthn/credentials/${credentialIdOf(visible)}`)
+			.body({password: account.password})
+			.expect(HTTP_STATUS.NO_CONTENT)
+			.execute();
+		expect(await getUserRepository().listWebAuthnCredentials(userId)).toEqual([]);
+	});
+
+	it('has no way to attach the old passkey to another one', async () => {
+		const {account, legacy} = await createAssignedAccount();
+		await runNativeSudoBridge(harness, account.token, legacy);
+		const target = createWebAuthnDevice();
+		await registerPasskey(harness, account.token, target, {password: account.password}, 'Phone', TARGET_ORIGIN);
+		await createBuilder(harness, account.token)
+			.delete(MIGRATION_PATH)
+			.header('origin', TARGET_ORIGIN)
+			.expect(HTTP_STATUS.NOT_FOUND)
+			.execute();
+		expect((await listPasskeys(harness, account.token)).map((cred) => cred.id).sort()).toEqual(
+			[credentialIdOf(legacy), credentialIdOf(target)].sort(),
+		);
+	});
+
+	it('never lets a migration challenge through the normal registration route', async () => {
+		const {account, legacy} = await createAssignedAccount();
+		await runNativeSudoBridge(harness, account.token, legacy);
+		const options = await migrationOptions(account.token);
+		await createBuilder(harness, account.token)
+			.post('/users/@me/mfa/webauthn/credentials')
+			.header('origin', TARGET_ORIGIN)
+			.body({
+				response: createRegistrationResponse(createWebAuthnDevice(), options, 'Sneaky'),
+				challenge: options.challenge,
+				name: 'Sneaky',
+			})
+			.expect(HTTP_STATUS.BAD_REQUEST, APIErrorCodes.INVALID_WEBAUTHN_CREDENTIAL)
+			.execute();
+	});
+
+	it('creates one credential when two updates race', async () => {
+		const {account, legacy} = await createAssignedAccount();
+		await runNativeSudoBridge(harness, account.token, legacy);
+		const first = await migrationOptions(account.token);
+		const second = await migrationOptions(account.token);
+		const results = await Promise.all(
+			[first, second].map((options) =>
+				completeMigration(account.token, createWebAuthnDevice(), options)
+					.expect(HTTP_STATUS.NO_CONTENT)
+					.executeWithResponse()
+					.then(
+						() => 'ok',
+						() => 'failed',
+					),
+			),
+		);
+		expect(results.sort()).toEqual(['failed', 'ok']);
+		const credentials = await listPasskeys(harness, account.token);
+		expect(credentials).toHaveLength(1);
+		expect(credentials[0].rp_id).toBe(TARGET_RP_ID);
+	});
+});
@@ -0,0 +1,232 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import {createAuthHarness, createTestAccount, type TestAccount} from '@app/api/auth/tests/AuthTestUtils';
+import {
+	LEGACY_ORIGIN,
+	LEGACY_RP_ID,
+	listPasskeys,
+	registerPasskey,
+	TARGET_ORIGIN,
+	TARGET_RP_ID,
+} from '@app/api/auth/tests/PasskeyTestUtils';
+import {
+	createAuthenticationResponse,
+	createWebAuthnDevice,
+	type WebAuthnAuthenticationOptions,
+	type WebAuthnDevice,
+	type WebAuthnRegistrationOptions,
+} from '@app/api/auth/tests/WebAuthnTestUtils';
+import {createUserID} from '@app/api/BrandedTypes';
+import {getConfig} from '@app/api/Config';
+import {getUserRepository} from '@app/api/middleware/ServiceSingletons';
+import type {ApiTestHarness} from '@app/api/test/ApiTestHarness';
+import {HTTP_STATUS} from '@app/api/test/TestConstants';
+import {createBuilder, createBuilderWithoutAuth} from '@app/api/test/TestRequestBuilder';
+import {APIErrorCodes} from '@fluxer/constants/src/ApiErrorCodes';
+import {afterAll, afterEach, beforeAll, beforeEach, describe, expect, it} from 'vitest';
+
+function credentialIdOf(device: WebAuthnDevice): string {
+	return device.credentialId.toString('base64url');
+}
+
+describe('Passkey relying party selection', () => {
+	let harness: ApiTestHarness;
+
+	beforeAll(async () => {
+		harness = await createAuthHarness();
+	});
+
+	beforeEach(async () => {
+		await harness.reset();
+	});
+
+	afterEach(() => {
+		getConfig().instance.selfHosted = false;
+	});
+
+	afterAll(async () => {
+		await harness?.shutdown();
+	});
+
+	async function registrationRpId(account: TestAccount, origin?: string): Promise<string> {
+		const builder = createBuilder<WebAuthnRegistrationOptions>(harness, account.token)
+			.post('/users/@me/mfa/webauthn/credentials/registration-options')
+			.body({password: account.password});
+		if (origin) builder.header('origin', origin);
+		return (await builder.execute()).rp.id;
+	}
+
+	async function discoverableOptions(origin?: string): Promise<WebAuthnAuthenticationOptions> {
+		const builder = createBuilderWithoutAuth<WebAuthnAuthenticationOptions>(harness)
+			.post('/auth/webauthn/authentication-options')
+			.body(null);
+		if (origin) builder.header('origin', origin);
+		return builder.execute();
+	}
+
+	async function sudoOptions(token: string, origin?: string): Promise<WebAuthnAuthenticationOptions> {
+		const builder = createBuilder<WebAuthnAuthenticationOptions>(harness, token)
+			.post('/users/@me/sudo/webauthn/authentication-options')
+			.body(null);
+		if (origin) builder.header('origin', origin);
+		return builder.execute();
+	}
+
+	async function createMixedAccount(): Promise<{account: TestAccount; legacy: WebAuthnDevice; target: WebAuthnDevice}> {
+		const account = await createTestAccount(harness);
+		const legacy = createWebAuthnDevice();
+		const target = createWebAuthnDevice();
+		await registerPasskey(harness, account.token, legacy, {password: account.password}, 'Old');
+		await registerPasskey(harness, account.token, target, {password: account.password}, 'New', TARGET_ORIGIN);
+		return {account, legacy, target};
+	}
+
+	it('uses the new relying party only for requests from the new origin', async () => {
+		const account = await createTestAccount(harness);
+		expect(await registrationRpId(account)).toBe(LEGACY_RP_ID);
+		expect(await registrationRpId(account, LEGACY_ORIGIN)).toBe(LEGACY_RP_ID);
+		expect(await registrationRpId(account, TARGET_ORIGIN)).toBe(TARGET_RP_ID);
+		expect((await discoverableOptions()).rpId).toBe(LEGACY_RP_ID);
+		expect((await discoverableOptions(LEGACY_ORIGIN)).rpId).toBe(LEGACY_RP_ID);
+		expect((await discoverableOptions(TARGET_ORIGIN)).rpId).toBe(TARGET_RP_ID);
+	});
+
+	it('keeps the legacy relying party everywhere on a self-hosted instance', async () => {
+		getConfig().instance.selfHosted = true;
+		const account = await createTestAccount(harness);
+		expect(await registrationRpId(account, TARGET_ORIGIN)).toBe(LEGACY_RP_ID);
+		expect((await discoverableOptions(TARGET_ORIGIN)).rpId).toBe(LEGACY_RP_ID);
+	});
+
+	it('stores and exposes the relying party of each passkey', async () => {
+		const {account, legacy, target} = await createMixedAccount();
+		const credentials = await listPasskeys(harness, account.token);
+		expect(credentials.map(({id, rp_id}) => ({id, rp_id}))).toEqual(
+			expect.arrayContaining([
+				{id: credentialIdOf(legacy), rp_id: LEGACY_RP_ID},
+				{id: credentialIdOf(target), rp_id: TARGET_RP_ID},
+			]),
+		);
+		const legacyRow = await getUserRepository().getWebAuthnCredential(
+			createUserID(BigInt(account.userId)),
+			credentialIdOf(legacy),
+		);
+		expect(legacyRow?.rpId).toBeNull();
+	});
+
+	it('keeps the legacy options unchanged for a legacy-only account off the new origin', async () => {
+		const account = await createTestAccount(harness);
+		const device = createWebAuthnDevice();
+		await registerPasskey(harness, account.token, device, {password: account.password}, 'Old');
+		for (const origin of [undefined, LEGACY_ORIGIN]) {
+			const options = await sudoOptions(account.token, origin);
+			expect(options.rpId).toBe(LEGACY_RP_ID);
+			expect(options.allowCredentials?.map((cred) => cred.id)).toEqual([credentialIdOf(device)]);
+			expect(options.userVerification).toBe('discouraged');
+		}
+	});
+
+	it('offers one relying party group per request', async () => {
+		const {account, legacy, target} = await createMixedAccount();
+		const onTarget = await sudoOptions(account.token, TARGET_ORIGIN);
+		expect(onTarget.rpId).toBe(TARGET_RP_ID);
+		expect(onTarget.allowCredentials?.map((cred) => cred.id)).toEqual([credentialIdOf(target)]);
+		const offTarget = await sudoOptions(account.token);
+		expect(offTarget.rpId).toBe(LEGACY_RP_ID);
+		expect(offTarget.allowCredentials?.map((cred) => cred.id)).toEqual([credentialIdOf(legacy)]);
+	});
+
+	it('falls back to the other group when the preferred one is empty', async () => {
+		const legacyOnly = await createTestAccount(harness);
+		const legacy = createWebAuthnDevice();
+		await registerPasskey(harness, legacyOnly.token, legacy, {password: legacyOnly.password}, 'Old');
+		expect((await sudoOptions(legacyOnly.token, TARGET_ORIGIN)).rpId).toBe(LEGACY_RP_ID);
+		const targetOnly = await createTestAccount(harness);
+		const target = createWebAuthnDevice();
+		await registerPasskey(harness, targetOnly.token, target, {password: targetOnly.password}, 'New', TARGET_ORIGIN);
+		expect((await sudoOptions(targetOnly.token)).rpId).toBe(TARGET_RP_ID);
+	});
+
+	it('rejects a passkey from another relying party before the test mode shortcut', async () => {
+		const {legacy} = await createMixedAccount();
+		const options = await discoverableOptions(TARGET_ORIGIN);
+		await createBuilderWithoutAuth(harness)
+			.post('/auth/webauthn/authenticate')
+			.header('origin', TARGET_ORIGIN)
+			.body({response: createAuthenticationResponse(legacy, options), challenge: options.challenge})
+			.expect(HTTP_STATUS.UNAUTHORIZED, APIErrorCodes.PASSKEY_AUTHENTICATION_FAILED)
+			.execute();
+	});
+
+	it('rejects a passkey outside the offered list before the test mode shortcut', async () => {
+		const account = await createTestAccount(harness);
+		const visible = createWebAuthnDevice();
+		const superseded = createWebAuthnDevice();
+		await registerPasskey(harness, account.token, visible, {password: account.password}, 'Visible');
+		await registerPasskey(harness, account.token, superseded, {password: account.password}, 'Superseded');
+		await getUserRepository().setWebAuthnCredentialSupersededBy(
+			createUserID(BigInt(account.userId)),
+			credentialIdOf(superseded),
+			credentialIdOf(visible),
+		);
+		const options = await sudoOptions(account.token, TARGET_ORIGIN);
+		expect(options.rpId).toBe(LEGACY_RP_ID);
+		expect(options.allowCredentials?.map((cred) => cred.id)).toEqual([credentialIdOf(visible)]);
+		await createBuilder(harness, account.token)
+			.patch(`/users/@me/mfa/webauthn/credentials/${credentialIdOf(visible)}`)
+			.header('origin', TARGET_ORIGIN)
+			.body({
+				name: 'Renamed',
+				mfa_method: 'webauthn',
+				webauthn_response: createAuthenticationResponse(superseded, options),
+				webauthn_challenge: options.challenge,
+			})
+			.expect(HTTP_STATUS.BAD_REQUEST)
+			.execute();
+		const retry = await sudoOptions(account.token, TARGET_ORIGIN);
+		await createBuilder(harness, account.token)
+			.patch(`/users/@me/mfa/webauthn/credentials/${credentialIdOf(visible)}`)
+			.header('origin', TARGET_ORIGIN)
+			.body({
+				name: 'Renamed',
+				mfa_method: 'webauthn',
+				webauthn_response: createAuthenticationResponse(visible, retry),
+				webauthn_challenge: retry.challenge,
+			})
+			.expect(HTTP_STATUS.NO_CONTENT)
+			.execute();
+	});
+
+	it('accepts a superseded passkey only off the new origin', async () => {
+		const account = await createTestAccount(harness);
+		const legacy = createWebAuthnDevice();
+		const target = createWebAuthnDevice();
+		await registerPasskey(harness, account.token, legacy, {password: account.password}, 'Old');
+		await registerPasskey(harness, account.token, target, {password: account.password}, 'New', TARGET_ORIGIN);
+		await getUserRepository().setWebAuthnCredentialSupersededBy(
+			createUserID(BigInt(account.userId)),
+			credentialIdOf(legacy),
+			credentialIdOf(target),
+		);
+		expect((await listPasskeys(harness, account.token)).map((cred) => cred.id)).toEqual([credentialIdOf(target)]);
+
+		const offTarget = await discoverableOptions();
+		await createBuilderWithoutAuth(harness)
+			.post('/auth/webauthn/authenticate')
+			.body({response: createAuthenticationResponse(legacy, offTarget), challenge: offTarget.challenge})
+			.expect(HTTP_STATUS.OK)
+			.execute();
+		const sudoOffTarget = await sudoOptions(account.token);
+		expect(sudoOffTarget.allowCredentials?.map((cred) => cred.id)).toEqual([credentialIdOf(legacy)]);
+
+		const onTarget = await discoverableOptions(TARGET_ORIGIN);
+		await createBuilderWithoutAuth(harness)
+			.post('/auth/webauthn/authenticate')
+			.header('origin', TARGET_ORIGIN)
+			.body({response: createAuthenticationResponse(legacy, onTarget), challenge: onTarget.challenge})
+			.expect(HTTP_STATUS.UNAUTHORIZED, APIErrorCodes.PASSKEY_AUTHENTICATION_FAILED)
+			.execute();
+		const sudoOnTarget = await sudoOptions(account.token, TARGET_ORIGIN);
+		expect(sudoOnTarget.allowCredentials?.map((cred) => cred.id)).toEqual([credentialIdOf(target)]);
+	});
+});
@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import {createHash, randomBytes} from 'node:crypto';
+import {
+	createAuthenticationResponse,
+	createRegistrationResponse,
+	type WebAuthnAuthenticationOptions,
+	type WebAuthnDevice,
+	type WebAuthnRegistrationOptions,
+} from '@app/api/auth/tests/WebAuthnTestUtils';
+import {getInstanceConfigRepository} from '@app/api/middleware/ServiceSingletons';
+import type {ApiTestHarness} from '@app/api/test/ApiTestHarness';
+import {createBuilder, createBuilderWithoutAuth} from '@app/api/test/TestRequestBuilder';
+import {DEFAULT_DOMAIN_MIGRATION_CONFIG} from '@fluxer/schema/src/domains/admin/DomainMigrationSchemas';
+import type {
+	PasskeyBridgeFinishResponse,
+	PasskeyBridgeStartResponse,
+	PasskeyBridgeSudoRedeemResponse,
+} from '@fluxer/schema/src/domains/auth/PasskeyBridgeSchemas';
+
+export const TARGET_ORIGIN = 'https://fluxer.com';
+export const LEGACY_ORIGIN = 'https://web.fluxer.app';
+export const LEGACY_RP_ID = 'localhost';
+export const TARGET_RP_ID = 'fluxer.com';
+
+export interface PasskeyCredentialListItem {
+	id: string;
+	name: string;
+	rp_id: string;
+}
+
+export interface BridgeNonce {
+	nonce: string;
+	nonceHash: string;
+}
+
+export function createBridgeNonce(): BridgeNonce {
+	const nonce = randomBytes(32).toString('base64url');
+	return {nonce, nonceHash: createHash('sha256').update(nonce).digest('hex')};
+}
+
+export async function setDomainMigration(enabled: boolean, includedUserIds: Array<string> = []): Promise<void> {
+	await getInstanceConfigRepository().setDomainMigrationConfig({
+		...DEFAULT_DOMAIN_MIGRATION_CONFIG,
+		enabled,
+		included_user_ids: includedUserIds,
+	});
+}
+
+export async function registerPasskey(
+	harness: ApiTestHarness,
+	token: string,
+	device: WebAuthnDevice,
+	sudo: Record<string, unknown>,
+	name: string,
+	origin?: string,
+): Promise<void> {
+	const optionsBuilder = createBuilder<WebAuthnRegistrationOptions>(harness, token)
+		.post('/users/@me/mfa/webauthn/credentials/registration-options')
+		.body(sudo);
+	if (origin) optionsBuilder.header('origin', origin);
+	const options = await optionsBuilder.execute();
+	const registerBuilder = createBuilder(harness, token)
+		.post('/users/@me/mfa/webauthn/credentials')
+		.body({response: createRegistrationResponse(device, options, name), challenge: options.challenge, name})
+		.expect(204);
+	if (origin) registerBuilder.header('origin', origin);
+	await registerBuilder.execute();
+}
+
+export async function listPasskeys(harness: ApiTestHarness, token: string): Promise<Array<PasskeyCredentialListItem>> {
+	return createBuilder<Array<PasskeyCredentialListItem>>(harness, token)
+		.get('/users/@me/mfa/webauthn/credentials')
+		.execute();
+}
+
+export async function runNativeSudoBridge(
+	harness: ApiTestHarness,
+	token: string,
+	device: WebAuthnDevice,
+	nonce: BridgeNonce = createBridgeNonce(),
+): Promise<PasskeyBridgeSudoRedeemResponse> {
+	const start = await createBuilder<PasskeyBridgeStartResponse>(harness, token)
+		.post('/users/@me/passkey-bridge')
+		.header('origin', TARGET_ORIGIN)
+		.body({runner: 'native', nonce_hash: nonce.nonceHash})
+		.execute();
+	const {options} = await createBuilderWithoutAuth<{options: WebAuthnAuthenticationOptions}>(harness)
+		.post(`/auth/passkey-bridge/${start.ceremony_id}/options`)
+		.header('origin', TARGET_ORIGIN)
+		.execute();
+	const finish = await createBuilderWithoutAuth<PasskeyBridgeFinishResponse>(harness)
+		.post(`/auth/passkey-bridge/${start.ceremony_id}/complete`)
+		.header('origin', TARGET_ORIGIN)
+		.body({response: createAuthenticationResponse(device, options)})
+		.execute();
+	return createBuilder<PasskeyBridgeSudoRedeemResponse>(harness, token)
+		.post(`/users/@me/passkey-bridge/${start.ceremony_id}/redeem`)
+		.header('origin', TARGET_ORIGIN)
+		.body({nonce: nonce.nonce, completion_code: finish.completion_code})
+		.execute();
+}
@@ -129,6 +129,7 @@ export interface APIConfig {
 		apiPublic: string;
 		apiClient: string;
 		webApp: string;
+		webAppOrigins: Array<string>;
 		gateway: string;
 		media: string;
 		staticCdn: string;
@@ -1,18 +1,18 @@
 {
-    "auth.unknown_location": "Ubicación desconocida",
-    "billing.donation_description_monthly": "Donación mensual para apoyar a {product_name}",
-    "billing.donation_description_one_time": "Donación única para apoyar a {product_name}",
-    "billing.donation_description_yearly": "Donación anual para apoyar a {product_name}",
-    "billing.donation_name_one_time": "Donación a {product_name}",
-    "billing.donation_name_recurring": "Donación recurrente a {product_name}",
-    "billing.eu_withdrawal_waiver_checkout": "Si soy un consumidor de la UE/EEE, doy mi consentimiento expreso para que el contenido digital de {product_name} {premium_tier_name} se proporcione de inmediato y reconozco que pierdo mi derecho legal de desistimiento una vez que se otorgue el acceso. Esto no afecta otros derechos de consumo obligatorios. Consulta los [Términos de servicio]({terms_url}).",
-    "bulk_message_deletion.complete": "Terminamos de eliminar tus mensajes. Eliminamos {message_count, plural, =0 {0 mensajes} one {# mensaje} other {# mensajes}} de {channel_count, plural, =0 {0 lugares} one {# lugar} other {# lugares}}.",
-    "content.virus_detected": "Ese archivo fue marcado como potencialmente inseguro y se ha eliminado.",
-    "guild.bulk_create.emoji_limit": "Se alcanzó el límite máximo de emojis ({limit}).",
-    "guild.bulk_create.sticker_limit": "Se alcanzó el límite máximo de stickers ({limit}).",
-    "guild.bulk_create.unknown_error": "Error desconocido.",
-    "guild.default_category_text": "Canales de texto",
-    "guild.default_category_voice": "Canales de voz",
-    "guild.default_channel_text": "general",
-    "guild.default_channel_voice": "General"
+	"auth.unknown_location": "Ubicación desconocida",
+	"billing.donation_description_monthly": "Donación mensual para apoyar a {product_name}",
+	"billing.donation_description_one_time": "Donación única para apoyar a {product_name}",
+	"billing.donation_description_yearly": "Donación anual para apoyar a {product_name}",
+	"billing.donation_name_one_time": "Donación a {product_name}",
+	"billing.donation_name_recurring": "Donación recurrente a {product_name}",
+	"billing.eu_withdrawal_waiver_checkout": "Si soy un consumidor de la UE/EEE, doy mi consentimiento expreso para que el contenido digital de {product_name} {premium_tier_name} se proporcione de inmediato y reconozco que pierdo mi derecho legal de desistimiento una vez que se otorgue el acceso. Esto no afecta otros derechos de consumo obligatorios. Consulta los [Términos de servicio]({terms_url}).",
+	"bulk_message_deletion.complete": "Terminamos de eliminar tus mensajes. Eliminamos {message_count, plural, =0 {0 mensajes} one {# mensaje} other {# mensajes}} de {channel_count, plural, =0 {0 lugares} one {# lugar} other {# lugares}}.",
+	"content.virus_detected": "Ese archivo fue marcado como potencialmente inseguro y se ha eliminado.",
+	"guild.bulk_create.emoji_limit": "Se alcanzó el límite máximo de emojis ({limit}).",
+	"guild.bulk_create.sticker_limit": "Se alcanzó el límite máximo de stickers ({limit}).",
+	"guild.bulk_create.unknown_error": "Error desconocido.",
+	"guild.default_category_text": "Canales de texto",
+	"guild.default_category_voice": "Canales de voz",
+	"guild.default_channel_text": "general",
+	"guild.default_channel_voice": "General"
 }
@@ -100,6 +100,8 @@ export interface WebAuthnCredentialRow {
 	created_at: Date;
 	last_used_at: Nullish<Date>;
 	version: number;
+	rp_id: Nullish<string>;
+	superseded_by: Nullish<string>;
 }

 export interface EmailChangeTicketRow {
@@ -193,6 +195,8 @@ export const WEBAUTHN_CREDENTIAL_COLUMNS = [
 	'created_at',
 	'last_used_at',
 	'version',
+	'rp_id',
+	'superseded_by',
 ] as const satisfies ReadonlyArray<keyof WebAuthnCredentialRow>;

 export interface PhoneTokenRow {
@@ -8,6 +8,7 @@ import {RateLimitConfigs} from '@app/api/RateLimitConfig';
 import type {HonoApp} from '@app/api/types/HonoEnv';
 import {entityTagMatches} from '@app/api/utils/EntityTag';
 import {Headers as HttpHeaders} from '@fluxer/constants/src/Headers';
+import {resolveDomainMigrationAssignment} from '@fluxer/schema/src/domains/admin/DomainMigrationSchemas';
 import {resolveVoiceNoiseSuppressionAssignment} from '@fluxer/schema/src/domains/admin/VoiceNoiseSuppressionSchemas';
 import {ExperimentAssignmentsResponse} from '@fluxer/schema/src/domains/experiment/ExperimentSchemas';

@@ -28,9 +29,10 @@ export function ExperimentController(app: HonoApp) {
 		}),
 		async (ctx) => {
 			const instanceConfigRepository = ctx.get('instanceConfigRepository');
-			const [delivery, voiceConfig] = await Promise.all([
+			const [delivery, voiceConfig, domainMigrationConfig] = await Promise.all([
 				instanceConfigRepository.getExperimentDeliveryConfig(),
 				instanceConfigRepository.getVoiceNoiseSuppressionConfig(),
+				instanceConfigRepository.getDomainMigrationConfig(),
 			]);
 			const userId = ctx.get('user').id.toString();
 			const body: ExperimentAssignmentsResponse = {
@@ -38,6 +40,7 @@ export function ExperimentController(app: HonoApp) {
 				poll_jitter_percent: delivery.poll_jitter_percent,
 				assignments: {
 					voice_noise_suppression: resolveVoiceNoiseSuppressionAssignment(voiceConfig, userId),
+					domain_migration: resolveDomainMigrationAssignment(domainMigrationConfig, userId),
 				},
 			};
 			const etag = `"${createHash('sha256').update(JSON.stringify(body)).digest('hex')}"`;
@@ -6,6 +6,10 @@ import {type ApiTestHarness, createApiTestHarness} from '@app/api/test/ApiTestHa
 import {HTTP_STATUS} from '@app/api/test/TestConstants';
 import {createBuilder, createBuilderWithoutAuth} from '@app/api/test/TestRequestBuilder';
 import {AdminACLs} from '@fluxer/constants/src/AdminACLs';
+import {
+	DEFAULT_DOMAIN_MIGRATION_CONFIG,
+	INERT_DOMAIN_MIGRATION_ASSIGNMENT,
+} from '@fluxer/schema/src/domains/admin/DomainMigrationSchemas';
 import {
 	DEFAULT_VOICE_NOISE_SUPPRESSION_CONFIG,
 	INERT_VOICE_NOISE_SUPPRESSION_ASSIGNMENT,
@@ -15,6 +19,7 @@ import {
 	DEFAULT_EXPERIMENT_POLL_JITTER_PERCENT,
 	type ExperimentAssignmentsResponse,
 	type ExperimentDeliveryConfigResponse,
+	readDomainMigrationAssignment,
 	readVoiceNoiseSuppressionAssignment,
 } from '@fluxer/schema/src/domains/experiment/ExperimentSchemas';
 import {afterAll, beforeAll, beforeEach, describe, expect, it} from 'vitest';
@@ -51,6 +56,7 @@ describe('GET /experiments', () => {
 			poll_jitter_percent: DEFAULT_EXPERIMENT_POLL_JITTER_PERCENT,
 			assignments: {
 				voice_noise_suppression: INERT_VOICE_NOISE_SUPPRESSION_ASSIGNMENT,
+				domain_migration: INERT_DOMAIN_MIGRATION_ASSIGNMENT,
 			},
 		});
 	});
@@ -82,6 +88,52 @@ describe('GET /experiments', () => {
 		expect(readVoiceNoiseSuppressionAssignment(body).enabled).toBe(false);
 	});

+	it('populates the domain migration assignment key even when the rollout is disabled', async () => {
+		const account = await createTestAccount(harness);
+
+		const body = await createBuilder<ExperimentAssignmentsResponse>(harness, account.token).get(ENDPOINT).execute();
+
+		expect(Object.hasOwn(body.assignments, 'domain_migration')).toBe(true);
+		expect(readDomainMigrationAssignment(body).enabled).toBe(false);
+	});
+
+	it('resolves the domain migration caller through the allowlist', async () => {
+		const targeted = await createTestAccount(harness);
+		const untargeted = await createTestAccount(harness);
+		await getInstanceConfigRepository().setDomainMigrationConfig({
+			...DEFAULT_DOMAIN_MIGRATION_CONFIG,
+			enabled: true,
+			config_version: 4,
+			rollout_basis_points: 0,
+			included_user_ids: [targeted.userId],
+		});
+
+		const targetedBody = await createBuilder<ExperimentAssignmentsResponse>(harness, targeted.token)
+			.get(ENDPOINT)
+			.execute();
+		expect(targetedBody.assignments.domain_migration).toEqual({enabled: true});
+
+		const untargetedBody = await createBuilder<ExperimentAssignmentsResponse>(harness, untargeted.token)
+			.get(ENDPOINT)
+			.execute();
+		expect(untargetedBody.assignments.domain_migration).toEqual({enabled: false});
+	});
+
+	it('keeps the domain migration exclusion ahead of a full rollout', async () => {
+		const excluded = await createTestAccount(harness);
+		await getInstanceConfigRepository().setDomainMigrationConfig({
+			...DEFAULT_DOMAIN_MIGRATION_CONFIG,
+			enabled: true,
+			rollout_basis_points: 10000,
+			included_user_ids: [excluded.userId],
+			excluded_user_ids: [excluded.userId],
+		});
+
+		const body = await createBuilder<ExperimentAssignmentsResponse>(harness, excluded.token).get(ENDPOINT).execute();
+
+		expect(body.assignments.domain_migration).toEqual({enabled: false});
+	});
+
 	it('serves the delivery cadence from the delivery config and not from the voice config', async () => {
 		const account = await createTestAccount(harness);
 		await getInstanceConfigRepository().setExperimentDeliveryConfig({
@@ -196,6 +248,30 @@ describe('GET /experiments', () => {
 		});
 	});

+	it('serves a fresh body once the domain migration config changes', async () => {
+		const account = await createTestAccount(harness);
+
+		const first = await createBuilder<ExperimentAssignmentsResponse>(harness, account.token)
+			.get(ENDPOINT)
+			.executeWithResponse();
+		const staleEtag = first.response.headers.get('etag') as string;
+
+		await getInstanceConfigRepository().setDomainMigrationConfig({
+			...DEFAULT_DOMAIN_MIGRATION_CONFIG,
+			enabled: true,
+			config_version: 1,
+			rollout_basis_points: 10000,
+		});
+
+		const refreshed = await createBuilder<ExperimentAssignmentsResponse>(harness, account.token)
+			.get(ENDPOINT)
+			.header('If-None-Match', staleEtag)
+			.executeWithResponse();
+		expect(refreshed.response.status).toBe(HTTP_STATUS.OK);
+		expect(refreshed.response.headers.get('etag')).not.toBe(staleEtag);
+		expect(refreshed.json?.assignments.domain_migration).toEqual({enabled: true});
+	});
+
 	it('serves a fresh body once the delivery config changes', async () => {
 		const account = await createTestAccount(harness);

@@ -252,6 +328,47 @@ describe('GET /experiments', () => {
 		});
 	});

+	it('bumps the domain migration config version on every admin update without the client sending one', async () => {
+		const admin = await setUserACLs(harness, await createTestAccount(harness), [
+			AdminACLs.AUTHENTICATE,
+			AdminACLs.INSTANCE_CONFIG_VIEW,
+			AdminACLs.INSTANCE_CONFIG_UPDATE,
+		]);
+
+		const afterFirst = await createBuilder<{domain_migration: {config_version: number; enabled: boolean}}>(
+			harness,
+			admin.token,
+		)
+			.patch('/admin/instance/config')
+			.body({domain_migration: {enabled: true, rollout_basis_points: 10000}})
+			.execute();
+		expect(afterFirst.domain_migration).toMatchObject({config_version: 1, enabled: true});
+
+		const afterSecond = await createBuilder<{
+			domain_migration: {config_version: number; enabled: boolean; anonymous_rollout_basis_points: number};
+		}>(harness, admin.token)
+			.patch('/admin/instance/config')
+			.body({domain_migration: {anonymous_rollout_basis_points: 2500}})
+			.execute();
+		expect(afterSecond.domain_migration).toMatchObject({
+			config_version: 2,
+			enabled: true,
+			anonymous_rollout_basis_points: 2500,
+		});
+
+		const afterEmpty = await createBuilder<{domain_migration: {config_version: number; enabled: boolean}}>(
+			harness,
+			admin.token,
+		)
+			.patch('/admin/instance/config')
+			.body({domain_migration: {}})
+			.execute();
+		expect(afterEmpty.domain_migration).toMatchObject({config_version: 2, enabled: true});
+
+		const body = await createBuilder<ExperimentAssignmentsResponse>(harness, admin.token).get(ENDPOINT).execute();
+		expect(body.assignments.domain_migration).toEqual({enabled: true});
+	});
+
 	it('leaves the config version alone for an admin update that sets no field', async () => {
 		const admin = await setUserACLs(harness, await createTestAccount(harness), [
 			AdminACLs.AUTHENTICATE,
@@ -84,6 +84,41 @@ describe('stripNonJpegImageMetadataForUpload', () => {
 	});
 });

+function riffChunk(type: string, data: Uint8Array): Uint8Array {
+	const out = new Uint8Array(8 + data.length + (data.length & 1));
+	out.set(textBytes(type), 0);
+	new DataView(out.buffer).setUint32(4, data.length, true);
+	out.set(data, 8);
+	return out;
+}
+
+function webp(chunks: ReadonlyArray<Uint8Array>): Uint8Array {
+	const body = concatBytes(chunks);
+	const header = concatBytes([textBytes('RIFF'), new Uint8Array(4), textBytes('WEBP')]);
+	new DataView(header.buffer).setUint32(4, 4 + body.length, true);
+	return concatBytes([header, body]);
+}
+
+describe('stripNonJpegImageMetadataForUpload for WebP', () => {
+	it('drops EXIF and XMP chunks without re-encoding frames', async () => {
+		const vp8x = new Uint8Array(10);
+		vp8x[0] = 0x02 | 0x08 | 0x04;
+		const anmf = riffChunk('ANMF', new Uint8Array([9, 8, 7]));
+		const input = webp([
+			riffChunk('VP8X', vp8x),
+			riffChunk('ANIM', new Uint8Array(6)),
+			anmf,
+			riffChunk('EXIF', textBytes('GPS=1,2')),
+			riffChunk('XMP ', textBytes('private metadata')),
+		]);
+		const stripped = await stripNonJpegImageMetadataForUpload(input, 'image/webp');
+		const expectedVp8x = new Uint8Array(10);
+		expectedVp8x[0] = 0x02;
+		expect(stripped.contentType).toBe('image/webp');
+		expect(stripped.body).toEqual(webp([riffChunk('VP8X', expectedVp8x), riffChunk('ANIM', new Uint8Array(6)), anmf]));
+	});
+});
+
 describe('buildProcessedMediaObject', () => {
 	it('leaves non-media objects for plain copy', async () => {
 		await expect(buildProcessedMediaObject(textBytes('plain text'), 'text/plain')).resolves.toBeNull();
@@ -162,6 +162,8 @@ export async function stripNonJpegImageMetadataForUpload(
 			contentType: normalizedContentType === 'image/apng' ? 'image/apng' : 'image/png',
 		};
 	}
+	const strippedWebp = isWebp(data) ? stripWebpMetadataChunks(data) : null;
+	if (strippedWebp) return {body: strippedWebp, contentType: 'image/webp'};
 	const image = sharp(data, {animated: true});
 	const metadata = await image.metadata();
 	switch (metadata.format) {
@@ -242,6 +244,50 @@ function stripPngMetadataChunks(data: Uint8Array): Uint8Array {
 	return output;
 }

+const WEBP_CHUNKS_TO_KEEP = new Set(['VP8 ', 'VP8L', 'VP8X', 'ALPH', 'ANIM', 'ANMF', 'ICCP']);
+const WEBP_VP8X_EXIF_FLAG = 0x08;
+const WEBP_VP8X_XMP_FLAG = 0x04;
+
+function readFourCc(data: Uint8Array, offset: number): string {
+	return String.fromCharCode(data[offset]!, data[offset + 1]!, data[offset + 2]!, data[offset + 3]!);
+}
+
+function readU32LE(data: Uint8Array, offset: number): number {
+	return (data[offset]! | (data[offset + 1]! << 8) | (data[offset + 2]! << 16) | (data[offset + 3]! << 24)) >>> 0;
+}
+
+function isWebp(data: Uint8Array): boolean {
+	return data.length >= 12 && readFourCc(data, 0) === 'RIFF' && readFourCc(data, 8) === 'WEBP';
+}
+
+function stripWebpMetadataChunks(data: Uint8Array): Uint8Array | null {
+	const riffEnd = Math.min(data.length, 8 + readU32LE(data, 4));
+	const chunks: Array<Uint8Array> = [];
+	let offset = 12;
+	while (offset + 8 <= riffEnd) {
+		const length = readU32LE(data, offset + 4);
+		const chunkEnd = offset + 8 + length + (length & 1);
+		if (offset + 8 + length > riffEnd) return null;
+		const type = readFourCc(data, offset);
+		if (WEBP_CHUNKS_TO_KEEP.has(type)) {
+			const chunk = data.slice(offset, Math.min(chunkEnd, riffEnd));
+			if (type === 'VP8X' && length > 0) chunk[8] = (chunk[8] ?? 0) & ~(WEBP_VP8X_EXIF_FLAG | WEBP_VP8X_XMP_FLAG);
+			chunks.push(chunk);
+		}
+		offset = chunkEnd;
+	}
+	const bodyLength = chunks.reduce((sum, chunk) => sum + chunk.length, 0);
+	const output = new Uint8Array(12 + bodyLength);
+	output.set(data.subarray(0, 12));
+	new DataView(output.buffer).setUint32(4, 4 + bodyLength, true);
+	let cursor = 12;
+	for (const chunk of chunks) {
+		output.set(chunk, cursor);
+		cursor += chunk.length;
+	}
+	return output;
+}
+
 function imageExtensionForContentType(contentType: string): string {
 	if (contentType.includes('svg')) return 'svg';
 	if (contentType.includes('tiff')) return 'tiff';
@@ -18,6 +18,10 @@ import {InstanceConfigWriteRaceExecutor} from '@app/api/instance/tests/InstanceC
 import {startDockerContainer} from '@app/api/test/DockerTestContainer';
 import {InMemoryCassandraQueryExecutor} from '@app/api/test/InMemoryCassandraQueryExecutor';
 import {MockKVProvider} from '@app/api/test/mocks/MockKVProvider';
+import {
+	DEFAULT_DOMAIN_MIGRATION_CONFIG,
+	type DomainMigrationConfig,
+} from '@fluxer/schema/src/domains/admin/DomainMigrationSchemas';
 import {
 	DEFAULT_VOICE_NOISE_SUPPRESSION_CONFIG,
 	type VoiceNoiseSuppressionConfig,
@@ -35,6 +39,7 @@ import {
 import {afterAll, afterEach, beforeAll, beforeEach, describe, expect, it, vi} from 'vitest';

 const VOICE_NOISE_SUPPRESSION_CONFIG_KEY = 'voice_noise_suppression_config';
+const DOMAIN_MIGRATION_CONFIG_KEY = 'domain_migration_config';
 const EXPERIMENT_DELIVERY_CONFIG_KEY = 'experiment_delivery_config';
 const APP_PUBLIC_CONFIG_KEY = 'app_public_config';
 const INSTANCE_POLICY_CONFIG_KEY = 'instance_policy_config';
@@ -351,6 +356,92 @@ describe('InstanceConfigRepository', () => {
 		});
 	});

+	it('returns the default domain migration config when the key is absent', async () => {
+		const executor = new CountingInMemoryCassandraQueryExecutor();
+		setCassandraQueryExecutorForTesting(executor);
+		const kvProvider = new MockKVProvider();
+		const repository = createRepository(kvProvider);
+
+		await expect(repository.getDomainMigrationConfig()).resolves.toEqual(DEFAULT_DOMAIN_MIGRATION_CONFIG);
+	});
+
+	it.each([
+		{name: 'unparseable text', stored: 'not-json'},
+		{name: 'a json array', stored: '[]'},
+		{name: 'out-of-range values', stored: '{"rollout_basis_points":99999}'},
+		{name: 'a non-boolean enabled flag', stored: '{"enabled":"yes"}'},
+	])('falls back to the default domain migration config for $name', async ({stored}) => {
+		const executor = new CountingInMemoryCassandraQueryExecutor();
+		setCassandraQueryExecutorForTesting(executor);
+		const kvProvider = new MockKVProvider();
+		const repository = createRepository(kvProvider);
+
+		await repository.setConfig(DOMAIN_MIGRATION_CONFIG_KEY, stored);
+
+		await expect(repository.getDomainMigrationConfig()).resolves.toEqual(DEFAULT_DOMAIN_MIGRATION_CONFIG);
+	});
+
+	it('round-trips a stored domain migration config', async () => {
+		const executor = new CountingInMemoryCassandraQueryExecutor();
+		setCassandraQueryExecutorForTesting(executor);
+		const kvProvider = new MockKVProvider();
+		const repository = createRepository(kvProvider);
+
+		const config: DomainMigrationConfig = {
+			...DEFAULT_DOMAIN_MIGRATION_CONFIG,
+			enabled: true,
+			config_version: 5,
+			rollout_basis_points: 2500,
+			rollout_salt: 'domain-migration-v2',
+			included_user_ids: ['1400000000000000001'],
+			excluded_user_ids: ['1400000000000000002'],
+			anonymous_rollout_basis_points: 300,
+			standalone_forwarding: true,
+		};
+		await repository.setDomainMigrationConfig(config);
+
+		await expect(repository.getDomainMigrationConfig()).resolves.toEqual(config);
+	});
+
+	it('fills newly added domain migration fields from the schema defaults', async () => {
+		const executor = new CountingInMemoryCassandraQueryExecutor();
+		setCassandraQueryExecutorForTesting(executor);
+		const kvProvider = new MockKVProvider();
+		const repository = createRepository(kvProvider);
+
+		await repository.setConfig(
+			DOMAIN_MIGRATION_CONFIG_KEY,
+			JSON.stringify({enabled: true, config_version: 2, rollout_basis_points: 1000}),
+		);
+
+		await expect(repository.getDomainMigrationConfig()).resolves.toEqual({
+			...DEFAULT_DOMAIN_MIGRATION_CONFIG,
+			enabled: true,
+			config_version: 2,
+			rollout_basis_points: 1000,
+		});
+	});
+
+	it('publishes a refresh so another repository observes the domain migration config', async () => {
+		const executor = new CountingInMemoryCassandraQueryExecutor();
+		setCassandraQueryExecutorForTesting(executor);
+		const kvProvider = new MockKVProvider();
+		const reader = createRepository(kvProvider);
+		const writer = createRepository(kvProvider);
+
+		await expect(reader.getDomainMigrationConfig()).resolves.toEqual(DEFAULT_DOMAIN_MIGRATION_CONFIG);
+
+		await writer.setDomainMigrationConfig({
+			...DEFAULT_DOMAIN_MIGRATION_CONFIG,
+			enabled: true,
+			config_version: 1,
+		});
+
+		await vi.waitFor(async () => {
+			expect(await reader.getDomainMigrationConfig()).toMatchObject({enabled: true, config_version: 1});
+		});
+	});
+
 	it('returns the default experiment delivery config when the key is absent', async () => {
 		const executor = new CountingInMemoryCassandraQueryExecutor();
 		setCassandraQueryExecutorForTesting(executor);
@@ -28,6 +28,10 @@ import {
 	type PendingRegistrationResponse,
 	type RegistrationUrlResponse,
 } from '@fluxer/schema/src/domains/admin/AdminSchemas';
+import {
+	type DomainMigrationConfig,
+	DomainMigrationConfigSchema,
+} from '@fluxer/schema/src/domains/admin/DomainMigrationSchemas';
 import {
 	type GatewayRolloutConfig,
 	GatewayRolloutConfigSchema,
@@ -63,6 +67,7 @@ import {z} from 'zod';
 const GATEWAY_ROLLOUT_CONFIG_KEY = 'gateway_rollout_config';
 const VOICE_NOISE_SUPPRESSION_CONFIG_KEY = 'voice_noise_suppression_config';
 const PUSH_SERVICE_DELIVERY_CONFIG_KEY = 'push_service_delivery_config';
+const DOMAIN_MIGRATION_CONFIG_KEY = 'domain_migration_config';
 const EXPERIMENT_DELIVERY_CONFIG_KEY = 'experiment_delivery_config';
 const REGISTRATION_CONFIG_KEY = 'registration_config';
 const REGISTRATION_URLS_KEY = 'registration_urls';
@@ -370,6 +375,7 @@ type StoredConfigSection =
 	| 'gateway rollout'
 	| 'voice noise suppression'
 	| 'push service delivery'
+	| 'domain migration'
 	| 'experiment delivery'
 	| 'instance policy'
 	| 'integrations'
@@ -512,6 +518,10 @@ function parseStoredPushServiceDeliveryConfig(raw: string | null): PushServiceDe
 	return parseStoredConfigOrDefault(PushServiceDeliveryConfigSchema, raw, 'push service delivery');
 }

+function parseStoredDomainMigrationConfig(raw: string | null): DomainMigrationConfig {
+	return parseStoredConfigOrDefault(DomainMigrationConfigSchema, raw, 'domain migration');
+}
+
 function parseStoredExperimentDeliveryConfig(raw: string | null): ExperimentDeliveryConfig {
 	return parseStoredConfigOrDefault(ExperimentDeliveryConfigSchema, raw, 'experiment delivery');
 }
@@ -1160,6 +1170,7 @@ export class InstanceConfigRepository {
 		);
 		parseStoredVoiceNoiseSuppressionConfig(snapshot.get(VOICE_NOISE_SUPPRESSION_CONFIG_KEY) ?? null);
 		parseStoredPushServiceDeliveryConfig(snapshot.get(PUSH_SERVICE_DELIVERY_CONFIG_KEY) ?? null);
+		parseStoredDomainMigrationConfig(snapshot.get(DOMAIN_MIGRATION_CONFIG_KEY) ?? null);
 		parseStoredExperimentDeliveryConfig(snapshot.get(EXPERIMENT_DELIVERY_CONFIG_KEY) ?? null);
 		const policy = parseStoredInstancePolicyConfig(snapshot.get(INSTANCE_POLICY_CONFIG_KEY) ?? null);
 		checkStoredConfig('registration', () =>
@@ -1273,6 +1284,27 @@ export class InstanceConfigRepository {
 		);
 	}

+	async getDomainMigrationConfig(): Promise<DomainMigrationConfig> {
+		const raw = await this.getConfig(DOMAIN_MIGRATION_CONFIG_KEY);
+		return parseStoredDomainMigrationConfig(raw);
+	}
+
+	async setDomainMigrationConfig(config: DomainMigrationConfig): Promise<void> {
+		await this.updateDomainMigrationConfig(() => config);
+	}
+
+	updateDomainMigrationConfig(
+		update: (current: DomainMigrationConfig) => DomainMigrationConfig,
+	): Promise<DomainMigrationConfig> {
+		return this.updateStoredConfig(DOMAIN_MIGRATION_CONFIG_KEY, (raw) =>
+			validateStoredConfig(
+				DomainMigrationConfigSchema,
+				update(parseStoredDomainMigrationConfig(raw)),
+				'domain migration',
+			),
+		);
+	}
+
 	async getExperimentDeliveryConfig(): Promise<ExperimentDeliveryConfig> {
 		const raw = await this.getConfig(EXPERIMENT_DELIVERY_CONFIG_KEY);
 		return parseStoredExperimentDeliveryConfig(raw);
@@ -8,6 +8,7 @@ import type {LimitConfigService} from '@app/api/limits/LimitConfigService';
 import {InMemoryCassandraQueryExecutor} from '@app/api/test/InMemoryCassandraQueryExecutor';
 import {MockKVProvider} from '@app/api/test/mocks/MockKVProvider';
 import type {HonoEnv} from '@app/api/types/HonoEnv';
+import {DEFAULT_DOMAIN_MIGRATION_CONFIG} from '@fluxer/schema/src/domains/admin/DomainMigrationSchemas';
 import {Hono} from 'hono';
 import {afterEach, describe, expect, it} from 'vitest';

@@ -96,4 +97,36 @@ describe('InstanceController discovery captcha', () => {
 			turnstile_site_key: 'turnstile-site-key',
 		});
 	});
+
+	it('publishes the domain migration kill switch and anonymous rollout without the targeting lists', async () => {
+		const repository = createRepository();
+		const app = createApp(repository);
+
+		const initial = await app.request('http://localhost/.well-known/fluxer');
+		expect(((await initial.json()) as {domain_migration: unknown}).domain_migration).toEqual({
+			enabled: false,
+			anonymous_rollout_basis_points: 0,
+			rollout_salt: 'domain-migration-v1',
+			standalone_forwarding: false,
+		});
+
+		await repository.setDomainMigrationConfig({
+			...DEFAULT_DOMAIN_MIGRATION_CONFIG,
+			enabled: true,
+			config_version: 2,
+			rollout_basis_points: 100,
+			anonymous_rollout_basis_points: 1500,
+			included_user_ids: ['1400000000000000001'],
+			standalone_forwarding: true,
+		});
+
+		const updated = await app.request('http://localhost/.well-known/fluxer');
+		expect(updated.headers.get('etag')).not.toBe(initial.headers.get('etag'));
+		expect(((await updated.json()) as {domain_migration: unknown}).domain_migration).toEqual({
+			enabled: true,
+			anonymous_rollout_basis_points: 1500,
+			rollout_salt: 'domain-migration-v1',
+			standalone_forwarding: true,
+		});
+	});
 });
@@ -16,6 +16,7 @@ import type {HonoEnv} from '@app/api/types/HonoEnv';
 import {API_CODE_VERSION} from '@fluxer/constants/src/AppConstants';
 import {buildDiscoveryResponse, type DiscoveryStaticInput} from '@fluxer/instance_bootstrap/src/BuildDiscovery';
 import type {InstanceAppPublic} from '@fluxer/instance_bootstrap/src/Types';
+import {toDomainMigrationDiscovery} from '@fluxer/schema/src/domains/admin/DomainMigrationSchemas';
 import {WellKnownFluxerResponse} from '@fluxer/schema/src/domains/instance/InstanceSchemas';
 import type {Hono} from 'hono';

@@ -102,15 +103,16 @@ export function InstanceController(app: Hono<HonoEnv>) {
 			const limits = ctx.get('limitConfigService').getConfigWireFormat();
 			const sso = await ctx.get('ssoService').getPublicStatus();
 			const instanceConfigRepository = ctx.get('instanceConfigRepository');
-			const [registration, community, services, appPublicConfig, captcha, email] = await Promise.all([
+			const [registration, community, services, appPublicConfig, captcha, email, domainMigration] = await Promise.all([
 				instanceConfigRepository.getRegistrationPublicConfig(),
 				instanceConfigRepository.getInstanceCommunityPublicConfig(),
 				instanceConfigRepository.getResolvedServicesConfig(),
 				instanceConfigRepository.getAppPublicConfig(),
 				instanceConfigRepository.getEffectiveCaptchaConfig(),
 				instanceConfigRepository.getEffectiveEmailConfig(),
+				instanceConfigRepository.getDomainMigrationConfig(),
 			]);
-			const response = buildDiscoveryResponse(
+			const discovery = buildDiscoveryResponse(
 				buildDiscoveryStaticInput(
 					gifService,
 					{
@@ -133,6 +135,7 @@ export function InstanceController(app: Hono<HonoEnv>) {
 					limits,
 				},
 			);
+			const response = {...discovery, domain_migration: toDomainMigrationDiscovery(domainMigration)};
 			discoveryValidators = nextDiscoveryValidators(response, discoveryValidators);
 			ctx.header('ETag', discoveryValidators.etag);
 			ctx.header('Last-Modified', discoveryValidators.lastModified.toUTCString());
@@ -1,11 +1,17 @@
 // SPDX-License-Identifier: AGPL-3.0-or-later

+import {Config} from '@app/api/Config';
 import {InvalidApiOriginError} from '@fluxer/errors/src/domains/core/InvalidApiOriginError';
 import type {Context, Next} from 'hono';

+const LEGACY_APP_ORIGINS = ['https://web.fluxer.app', 'https://web.canary.fluxer.app'];
+
 export async function BlockAppOriginMiddleware(ctx: Context, next: Next) {
 	const origin = ctx.req.header('origin');
-	if (origin === 'https://web.fluxer.app' || origin === 'https://web.canary.fluxer.app') {
+	if (
+		origin !== undefined &&
+		(LEGACY_APP_ORIGINS.includes(origin) || Config.endpoints.webAppOrigins.includes(origin))
+	) {
 		throw new InvalidApiOriginError();
 	}
 	await next();
@@ -12,6 +12,8 @@ export class WebAuthnCredential {
 	readonly createdAt: Date;
 	readonly lastUsedAt: Date | null;
 	readonly version: number;
+	readonly rpId: string | null;
+	readonly supersededBy: string | null;

 	constructor(row: WebAuthnCredentialRow) {
 		this.credentialId = row.credential_id;
@@ -22,6 +24,8 @@ export class WebAuthnCredential {
 		this.createdAt = row.created_at;
 		this.lastUsedAt = row.last_used_at ?? null;
 		this.version = row.version;
+		this.rpId = row.rp_id ?? null;
+		this.supersededBy = row.superseded_by ?? null;
 	}

 	toRow(userId: UserID): WebAuthnCredentialRow {
@@ -35,6 +39,8 @@ export class WebAuthnCredential {
 			created_at: this.createdAt,
 			last_used_at: this.lastUsedAt,
 			version: this.version,
+			rp_id: this.rpId,
+			superseded_by: this.supersededBy,
 		};
 	}
 }
@@ -104,6 +104,10 @@ export const AuthRateLimitConfigs = {
 		bucket: 'mfa:webauthn:two_factor',
 		config: {limit: 10, windowMs: ms('1 minute')},
 	} as RouteRateLimitConfig,
+	MFA_WEBAUTHN_MIGRATION: {
+		bucket: 'mfa:webauthn:migration',
+		config: {limit: 20, windowMs: ms('1 minute')},
+	} as RouteRateLimitConfig,
 	PHONE_SEND_VERIFICATION: {
 		bucket: 'phone:send_verification',
 		config: {limit: 5, windowMs: ms('1 minute')},
@@ -132,6 +136,34 @@ export const AuthRateLimitConfigs = {
 		bucket: 'auth:handoff:cancel',
 		config: {limit: 10, windowMs: ms('1 minute')},
 	} as RouteRateLimitConfig,
+	AUTH_ORIGIN_HANDOFF_CREATE: {
+		bucket: 'auth:origin_handoff:create',
+		config: {limit: 3, windowMs: ms('10 minutes')},
+	} as RouteRateLimitConfig,
+	AUTH_ORIGIN_HANDOFF_REDEEM: {
+		bucket: 'auth:origin_handoff:redeem',
+		config: {limit: 10, windowMs: ms('1 minute')},
+	} as RouteRateLimitConfig,
+	AUTH_PASSKEY_BRIDGE_START: {
+		bucket: 'auth:passkey_bridge:start',
+		config: {limit: 10, windowMs: ms('1 minute')},
+	} as RouteRateLimitConfig,
+	AUTH_PASSKEY_BRIDGE_CEREMONY: {
+		bucket: 'auth:passkey_bridge:ceremony',
+		config: {limit: 20, windowMs: ms('1 minute')},
+	} as RouteRateLimitConfig,
+	AUTH_PASSKEY_BRIDGE_REDEEM: {
+		bucket: 'auth:passkey_bridge:redeem',
+		config: {limit: 60, windowMs: ms('1 minute')},
+	} as RouteRateLimitConfig,
+	USER_PASSKEY_BRIDGE_START: {
+		bucket: 'mfa:passkey_bridge:start',
+		config: {limit: 10, windowMs: ms('1 minute')},
+	} as RouteRateLimitConfig,
+	USER_PASSKEY_BRIDGE_REDEEM: {
+		bucket: 'mfa:passkey_bridge:redeem',
+		config: {limit: 60, windowMs: ms('1 minute')},
+	} as RouteRateLimitConfig,
 	SUDO_WEBAUTHN_OPTIONS: {
 		bucket: 'sudo:webauthn:options',
 		config: {limit: 10, windowMs: ms('1 minute')},
@@ -3,6 +3,7 @@
 import {createHash} from 'node:crypto';
 import type {ApiContext} from '@app/api/ApiContext';
 import * as AuthSession from '@app/api/auth/AuthSession';
+import {visibleWebAuthnCredentials} from '@app/api/auth/services/PasskeyRelyingParty';
 import type {ChannelID, GuildID, UserID} from '@app/api/BrandedTypes';
 import {
 	createChannelID,
@@ -75,6 +76,7 @@ import {
 	mapUserGuildSettingsToResponse,
 	mapUserSettingsToResponse,
 	mapUserToPrivateResponse,
+	mapWebAuthnCredentialToResponse,
 } from '@app/api/user/UserMappers';
 import {isUserAdult} from '@app/api/utils/AgeUtils';
 import {deriveDominantAvatarColor} from '@app/api/utils/AvatarColorUtils';
@@ -1199,12 +1201,9 @@ export class RpcService {
 			longitude: geoipLongitude,
 			rtc_regions: rtcRegions,
 			webauthn_credentials: timeRpcStepSync(responseBuildSteps, 'map_webauthn_credentials', () =>
-				userData.webAuthnCredentials.map((cred) => ({
-					id: cred.credentialId,
-					name: cred.name,
-					created_at: cred.createdAt.toISOString(),
-					last_used_at: cred.lastUsedAt?.toISOString() ?? null,
-				})),
+				visibleWebAuthnCredentials(userData.webAuthnCredentials).map((cred) =>
+					mapWebAuthnCredentialToResponse(cred, Config.auth.passkeys.rpId),
+				),
 			),
 			version,
 		};
@@ -39,7 +39,6 @@ import type Stripe from 'stripe';

 const PRODUCT_NAME = 'Fluxer';
 const PREMIUM_TIER_NAME = 'Plutonium';
-const TERMS_URL = 'https://fluxer.app/terms';
 export const EU_WITHDRAWAL_WAIVER_TEXT_VERSION = '2026-04-23';

 type CheckoutSessionCreateParams = Stripe.Checkout.SessionCreateParams;
@@ -226,7 +225,7 @@ export class StripeCheckoutService {
 					message: getContentMessage('billing.eu_withdrawal_waiver_checkout', user.locale, {
 						product_name: PRODUCT_NAME,
 						premium_tier_name: PREMIUM_TIER_NAME,
-						terms_url: TERMS_URL,
+						terms_url: `${Config.endpoints.marketing}/terms`,
 					}),
 				},
 			},
@@ -14,7 +14,7 @@ import {createRequestCache} from '@app/api/middleware/RequestCacheMiddleware';
 import {addGiftCodeDuration} from '@app/api/models/GiftCode';
 import type {User} from '@app/api/models/User';
 import type {IUserRepository} from '@app/api/user/IUserRepository';
-import {createPremiumClearPatch, getEffectivePremiumUntil} from '@app/api/user/UserHelpers';
+import {clearPerksSanitizedFlag, createPremiumClearPatch, getEffectivePremiumUntil} from '@app/api/user/UserHelpers';
 import {mapUserToPrivateResponse} from '@app/api/user/UserMappers';
 import {UserPremiumTypes} from '@fluxer/constants/src/UserConstants';
 import {MissingAccessError} from '@fluxer/errors/src/domains/core/MissingAccessError';
@@ -62,6 +62,7 @@ export class StripePremiumService {
 				premium_will_cancel: false,
 				premium_billing_cycle: billingCycle,
 				premium_grace_ends_at: null,
+				premium_flags: clearPerksSanitizedFlag(user.premiumFlags),
 			},
 			user.toRow(),
 		);
@@ -90,6 +91,7 @@ export class StripePremiumService {
 				premium_since: this.resolvePremiumSince(user.premiumSince, premiumSinceAnchor, now),
 				premium_until: null,
 				premium_lifetime_sequence: visionarySequence,
+				premium_flags: clearPerksSanitizedFlag(user.premiumFlags),
 				has_ever_purchased: hasEverPurchased,
 				premium_will_cancel: false,
 				premium_billing_cycle: null,
@@ -127,6 +129,7 @@ export class StripePremiumService {
 		};
 		if ((user.premiumType ?? 0) <= 0) {
 			patch.premium_type = premiumType;
+			patch.premium_flags = clearPerksSanitizedFlag(user.premiumFlags);
 			patch.premium_since = this.resolvePremiumSince(user.premiumSince, null, now);
 		}
 		if (hasEverPurchased && !user.hasEverPurchased) {
@@ -261,7 +261,7 @@ export class StripeRefundService {
 		const subscriptionId = refund.metadata.subscription_id;
 		if (subscriptionId) {
 			try {
-				await this.subscriptionService.cancelSubscriptionImmediately(user.id, 'self_serve_refund');
+				await this.subscriptionService.cancelSubscriptionImmediately(user.id, 'self_serve_refund', subscriptionId);
 			} catch (error) {
 				Logger.error(
 					{error, userId: user.id.toString(), subscriptionId},
@@ -174,7 +174,7 @@ export class StripeSubscriptionService {
 		}
 	}

-	async cancelSubscriptionImmediately(userId: UserID, reason?: string): Promise<void> {
+	async cancelSubscriptionImmediately(userId: UserID, reason?: string, expectedSubscriptionId?: string): Promise<void> {
 		if (!this.stripe) {
 			throw new StripePaymentNotAvailableError();
 		}
@@ -185,6 +185,18 @@ export class StripeSubscriptionService {
 		if (!user.stripeSubscriptionId) {
 			throw new StripeNoActiveSubscriptionError();
 		}
+		if (expectedSubscriptionId && user.stripeSubscriptionId !== expectedSubscriptionId) {
+			Logger.info(
+				{
+					userId: user.id.toString(),
+					expectedSubscriptionId,
+					currentSubscriptionId: user.stripeSubscriptionId,
+					reason: reason ?? null,
+				},
+				'Skipping immediate cancellation because the target subscription is no longer the current one',
+			);
+			return;
+		}
 		try {
 			const canceledSubscription = await this.stripe.subscriptions.cancel(
 				user.stripeSubscriptionId,
@@ -487,4 +487,90 @@ describe('StripeRefundService self-serve refund', () => {
 			expect(idempotencyKeys[1]).toContain('retry-1');
 		});
 	});
+	describe('self-serve refund teardown targeting', () => {
+		function trackingSubscriptionDeleteHandler(deleted: Array<string>) {
+			return http.delete(`${STRIPE_API_BASE}/v1/subscriptions/:id`, ({params}) => {
+				deleted.push(String(params.id));
+				return HttpResponse.json({id: params.id, object: 'subscription', status: 'canceled'});
+			});
+		}
+
+		function buildRefundUpdatedEvent(opts: {
+			eventId: string;
+			refundId: string;
+			userId: string;
+			invoiceId: string;
+			subscriptionId: string;
+		}): StripeWebhookEventData {
+			return {
+				id: opts.eventId,
+				type: 'refund.updated',
+				data: {
+					object: {
+						id: opts.refundId,
+						object: 'refund',
+						status: 'succeeded',
+						amount: 2500,
+						currency: 'usd',
+						metadata: {
+							refund_kind: 'self_serve',
+							user_id: opts.userId,
+							invoice_id: opts.invoiceId,
+							subscription_id: opts.subscriptionId,
+						},
+					},
+				},
+			};
+		}
+
+		test('leaves a newer subscription alone when the refunded one is no longer current', async () => {
+			server.use(...createStripeApiHandlers().handlers);
+			const deleted: Array<string> = [];
+			server.use(trackingSubscriptionDeleteHandler(deleted));
+			const account = await createTestAccount(harness);
+			const userId = createUserID(BigInt(account.userId));
+			await setStripeIds(harness, account, {
+				stripe_customer_id: MOCK_CUSTOMER_ID,
+				stripe_subscription_id: 'sub_bought_after_the_refund',
+			});
+			await sendWebhook(
+				buildRefundUpdatedEvent({
+					eventId: 'evt_stale_teardown',
+					refundId: 're_stale_teardown',
+					userId: account.userId,
+					invoiceId: 'in_stale_teardown',
+					subscriptionId: 'sub_refunded_and_already_gone',
+				}),
+			);
+			expect(deleted).toEqual([]);
+			const userRepository = new UserRepository();
+			const user = await userRepository.findUnique(userId);
+			expect(user!.stripeSubscriptionId).toBe('sub_bought_after_the_refund');
+		});
+
+		test('cancels the subscription when the refunded one is still current', async () => {
+			server.use(...createStripeApiHandlers().handlers);
+			const deleted: Array<string> = [];
+			server.use(trackingSubscriptionDeleteHandler(deleted));
+			const account = await createTestAccount(harness);
+			const userId = createUserID(BigInt(account.userId));
+			await setStripeIds(harness, account, {
+				stripe_customer_id: MOCK_CUSTOMER_ID,
+				stripe_subscription_id: MOCK_SUBSCRIPTION_ID,
+			});
+			await sendWebhook(
+				buildRefundUpdatedEvent({
+					eventId: 'evt_current_teardown',
+					refundId: 're_current_teardown',
+					userId: account.userId,
+					invoiceId: 'in_current_teardown',
+					subscriptionId: MOCK_SUBSCRIPTION_ID,
+				}),
+			);
+			expect(deleted).toEqual([MOCK_SUBSCRIPTION_ID]);
+			const userRepository = new UserRepository();
+			const user = await userRepository.findUnique(userId);
+			expect(user!.stripeSubscriptionId).toBeNull();
+		});
+	});
 });
@@ -275,6 +275,10 @@ export function createPremiumClearPatch(): Partial<UserRow> {
 	return mapExpiredPremiumFields(() => null) as Partial<UserRow>;
 }

+export function clearPerksSanitizedFlag(premiumFlags: number): number {
+	return premiumFlags & ~PremiumFlags.PERKS_SANITIZED;
+}
+
 const PROFILE_SUBSTRING_EXEMPT_FLAGS = UserFlags.STAFF;

 export function isProfileSubstringExempt(user: Pick<PremiumCheckable, 'flags'>): boolean {
@@ -9,6 +9,7 @@ import type {Relationship} from '@app/api/models/Relationship';
 import type {User} from '@app/api/models/User';
 import type {UserGuildSettings} from '@app/api/models/UserGuildSettings';
 import type {UserSettings} from '@app/api/models/UserSettings';
+import type {WebAuthnCredential} from '@app/api/models/WebAuthnCredential';
 import {canUseProfileTimezone, getRequiredActions} from '@app/api/user/UserHelpers';
 import {canUserAccessNsfwContent} from '@app/api/utils/AgeUtils';
 import type {ChannelMessageNotifications} from '@fluxer/constants/src/NotificationConstants';
@@ -26,6 +27,7 @@ import {
 	UserFlags,
 	UserPremiumTypes,
 } from '@fluxer/constants/src/UserConstants';
+import type {WebAuthnCredentialResponse} from '@fluxer/schema/src/domains/auth/AuthSchemas';
 import type {
 	RelationshipResponse,
 	UserGuildSettingsResponse,
@@ -420,3 +422,16 @@ export function mapUserGuildSettingsToResponse(settings: UserGuildSettings): Use
 		version: settings.version,
 	};
 }
+
+export function mapWebAuthnCredentialToResponse(
+	credential: WebAuthnCredential,
+	legacyRpId: string,
+): WebAuthnCredentialResponse {
+	return {
+		id: credential.credentialId,
+		name: credential.name,
+		created_at: credential.createdAt.toISOString(),
+		last_used_at: credential.lastUsedAt?.toISOString() ?? null,
+		rp_id: credential.rpId ?? legacyRpId,
+	};
+}
@@ -3,6 +3,7 @@
 import * as AuthSession from '@app/api/auth/AuthSession';
 import {requireSudoMode} from '@app/api/auth/services/SudoVerificationService';
 import {createGuildID, createUserID} from '@app/api/BrandedTypes';
+import {Config} from '@app/api/Config';
 import {DefaultUserOnly, LoginRequired, LoginRequiredAllowSuspicious} from '@app/api/middleware/AuthMiddleware';
 import {requireOAuth2ScopeForBearer} from '@app/api/middleware/OAuth2ScopeMiddleware';
 import {RateLimitMiddleware} from '@app/api/middleware/RateLimitMiddleware';
@@ -10,6 +11,7 @@ import {OpenAPI} from '@app/api/middleware/ResponseTypeMiddleware';
 import {SudoModeMiddleware} from '@app/api/middleware/SudoModeMiddleware';
 import {RateLimitConfigs} from '@app/api/RateLimitConfig';
 import type {HonoApp} from '@app/api/types/HonoEnv';
+import {classifyWebPushOrigin} from '@app/api/user/services/WebPushOriginReplacement';
 import {getCachedUserPartialResponse} from '@app/api/user/UserCacheHelpers';
 import {
 	mapUserGuildSettingsToResponse,
@@ -854,7 +856,7 @@ export function UserAccountController(app: HonoApp) {
 				'Registers a new push notification subscription for the current user. Takes push endpoint and encryption keys from a Web Push API subscription. Returns subscription ID for future reference.',
 		}),
 		async (ctx) => {
-			const {endpoint, keys, user_agent} = ctx.req.valid('json');
+			const {endpoint, keys, user_agent, installed_app} = ctx.req.valid('json');
 			const authSession = ctx.get('authSession');
 			const subscription = await ctx.get('userService').contentService.registerPushSubscription({
 				userId: ctx.get('user').id,
@@ -862,6 +864,8 @@ export function UserAccountController(app: HonoApp) {
 				endpoint,
 				keys,
 				userAgent: user_agent,
+				originKind: classifyWebPushOrigin(ctx.req.header('origin'), Config.instance.selfHosted),
+				installedApp: installed_app,
 			});
 			return ctx.json({subscription_id: subscription.subscriptionId});
 		},
@@ -883,7 +887,7 @@ export function UserAccountController(app: HonoApp) {
 				'Replaces an existing push subscription whose endpoint has been rotated by the browser (pushsubscriptionchange). Deletes the row keyed by the old endpoint and inserts a new one for the new endpoint.',
 		}),
 		async (ctx) => {
-			const {old_endpoint, endpoint, keys, user_agent} = ctx.req.valid('json');
+			const {old_endpoint, endpoint, keys, user_agent, installed_app} = ctx.req.valid('json');
 			const authSession = ctx.get('authSession');
 			const subscription = await ctx.get('userService').contentService.rotatePushSubscription({
 				userId: ctx.get('user').id,
@@ -892,6 +896,8 @@ export function UserAccountController(app: HonoApp) {
 				endpoint,
 				keys,
 				userAgent: user_agent,
+				originKind: classifyWebPushOrigin(ctx.req.header('origin'), Config.instance.selfHosted),
+				installedApp: installed_app,
 			});
 			return ctx.json({subscription_id: subscription.subscriptionId});
 		},
@@ -1,5 +1,10 @@
 // SPDX-License-Identifier: AGPL-3.0-or-later

+import {
+	completePasskeyMigration,
+	getPasskeyMigration,
+	getPasskeyMigrationRegistrationOptions,
+} from '@app/api/auth/services/PasskeyMigrationService';
 import {requireSudoMode} from '@app/api/auth/services/SudoVerificationService';
 import {Config} from '@app/api/Config';
 import {DefaultUserOnly, LoginRequired, LoginRequiredAllowSuspicious} from '@app/api/middleware/AuthMiddleware';
@@ -34,6 +39,10 @@ import {
 	WebAuthnTwoFactorRequest,
 	WebAuthnTwoFactorResponse,
 } from '@fluxer/schema/src/domains/auth/AuthSchemas';
+import {
+	PasskeyMigrationCompleteRequest,
+	PasskeyMigrationResponse,
+} from '@fluxer/schema/src/domains/auth/PasskeyMigrationSchemas';
 import {CredentialIdParam} from '@fluxer/schema/src/domains/common/CommonParamSchemas';
 import {EmptyBodyRequest} from '@fluxer/schema/src/domains/user/UserRequestSchemas';

@@ -347,7 +356,9 @@ export function UserAuthController(app: HonoApp) {
 			await requireSudoMode(ctx, user, body, {
 				issueSudoToken: false,
 			});
-			return ctx.json(await ctx.get('userAuthRequestService').generateWebAuthnRegistrationOptions(user));
+			return ctx.json(
+				await ctx.get('userAuthRequestService').generateWebAuthnRegistrationOptions(user, ctx.req.header('origin')),
+			);
 		},
 	);
 	app.post(
@@ -433,6 +444,78 @@ export function UserAuthController(app: HonoApp) {
 			return ctx.body(null, 204);
 		},
 	);
+	app.get(
+		'/users/@me/mfa/webauthn/migration',
+		RateLimitMiddleware(RateLimitConfigs.MFA_WEBAUTHN_MIGRATION),
+		LoginRequired,
+		DefaultUserOnly,
+		OpenAPI({
+			operationId: 'get_webauthn_migration',
+			summary: 'Get pending passkey update',
+			responseSchema: PasskeyMigrationResponse,
+			statusCode: 200,
+			security: ['bearerToken', 'sessionToken'],
+			tags: ['Users'],
+			description:
+				'Return the passkey this session can update to the new domain after using it within the last five minutes, or null.',
+		}),
+		async (ctx) => {
+			return ctx.json(await getPasskeyMigration(ctx.get('apiContext'), ctx.get('user').id, ctx.get('authSession')));
+		},
+	);
+	app.post(
+		'/users/@me/mfa/webauthn/migration/registration-options',
+		RateLimitMiddleware(RateLimitConfigs.MFA_WEBAUTHN_MIGRATION),
+		LoginRequired,
+		DefaultUserOnly,
+		OpenAPI({
+			operationId: 'get_webauthn_migration_registration_options',
+			summary: 'Get passkey update registration options',
+			responseSchema: WebAuthnChallengeResponse,
+			statusCode: 200,
+			security: ['bearerToken', 'sessionToken'],
+			tags: ['Users'],
+			description:
+				'Generate registration options for the passkey that replaces the pending one. Requires a pending passkey update for this session.',
+		}),
+		async (ctx) => {
+			return ctx.json(
+				await getPasskeyMigrationRegistrationOptions(
+					ctx.get('apiContext'),
+					ctx.get('user').id,
+					ctx.get('authSession'),
+					ctx.req.header('origin'),
+				),
+			);
+		},
+	);
+	app.post(
+		'/users/@me/mfa/webauthn/migration',
+		RateLimitMiddleware(RateLimitConfigs.MFA_WEBAUTHN_MIGRATION),
+		LoginRequired,
+		DefaultUserOnly,
+		Validator('json', PasskeyMigrationCompleteRequest),
+		OpenAPI({
+			operationId: 'complete_webauthn_migration',
+			summary: 'Complete passkey update',
+			responseSchema: null,
+			statusCode: 204,
+			security: ['bearerToken', 'sessionToken'],
+			tags: ['Users'],
+			description:
+				'Register the replacement passkey under the name of the pending one. The old passkey stops appearing in lists and is removed together with its replacement.',
+		}),
+		async (ctx) => {
+			await completePasskeyMigration(
+				ctx.get('apiContext'),
+				ctx.get('user').id,
+				ctx.get('authSession'),
+				ctx.req.header('origin'),
+				ctx.req.valid('json'),
+			);
+			return ctx.body(null, 204);
+		},
+	);
 	app.put(
 		'/users/@me/mfa/webauthn/two-factor',
 		RateLimitMiddleware(RateLimitConfigs.MFA_WEBAUTHN_TWO_FACTOR),
@@ -492,7 +575,9 @@ export function UserAuthController(app: HonoApp) {
 				'Generate WebAuthn challenge for sudo mode verification using a registered security key or biometric device.',
 		}),
 		async (ctx) => {
-			return ctx.json(await ctx.get('userAuthRequestService').getSudoWebAuthnOptions(ctx.get('user')));
+			return ctx.json(
+				await ctx.get('userAuthRequestService').getSudoWebAuthnOptions(ctx.get('user'), ctx.req.header('origin')),
+			);
 		},
 	);
 }
@@ -65,10 +65,12 @@ export interface IUserAuthRepository {
 		counter: bigint,
 		transports: Set<string> | null,
 		name: string,
+		rpId: string | null,
 	): Promise<void>;
 	updateWebAuthnCredentialCounter(userId: UserID, credentialId: string, counter: bigint): Promise<void>;
 	updateWebAuthnCredentialLastUsed(userId: UserID, credentialId: string): Promise<void>;
 	updateWebAuthnCredentialName(userId: UserID, credentialId: string, name: string): Promise<void>;
+	setWebAuthnCredentialSupersededBy(userId: UserID, credentialId: string, supersededBy: string): Promise<void>;
 	deleteWebAuthnCredential(userId: UserID, credentialId: string): Promise<void>;
 	getUserIdByCredentialId(credentialId: string): Promise<UserID | null>;
 	deleteAllWebAuthnCredentials(userId: UserID): Promise<void>;
@@ -193,8 +193,17 @@ export class UserAuthRepository implements IUserAuthRepository {
 		counter: bigint,
 		transports: Set<string> | null,
 		name: string,
+		rpId: string | null,
 	): Promise<void> {
-		return this.webAuthnRepository.createWebAuthnCredential(userId, credentialId, publicKey, counter, transports, name);
+		return this.webAuthnRepository.createWebAuthnCredential(
+			userId,
+			credentialId,
+			publicKey,
+			counter,
+			transports,
+			name,
+			rpId,
+		);
 	}

 	async updateWebAuthnCredentialCounter(userId: UserID, credentialId: string, counter: bigint): Promise<void> {
@@ -209,6 +218,10 @@ export class UserAuthRepository implements IUserAuthRepository {
 		return this.webAuthnRepository.updateWebAuthnCredentialName(userId, credentialId, name);
 	}

+	async setWebAuthnCredentialSupersededBy(userId: UserID, credentialId: string, supersededBy: string): Promise<void> {
+		return this.webAuthnRepository.setWebAuthnCredentialSupersededBy(userId, credentialId, supersededBy);
+	}
+
 	async deleteWebAuthnCredential(userId: UserID, credentialId: string): Promise<void> {
 		return this.webAuthnRepository.deleteWebAuthnCredential(userId, credentialId);
 	}
@@ -407,8 +407,9 @@ export class UserRepository implements IUserRepositoryAggregate {
 		counter: bigint,
 		transports: Set<string> | null,
 		name: string,
+		rpId: string | null,
 	): Promise<void> {
-		return this.authRepo.createWebAuthnCredential(userId, credentialId, publicKey, counter, transports, name);
+		return this.authRepo.createWebAuthnCredential(userId, credentialId, publicKey, counter, transports, name, rpId);
 	}

 	async updateWebAuthnCredentialCounter(userId: UserID, credentialId: string, counter: bigint): Promise<void> {
@@ -423,6 +424,10 @@ export class UserRepository implements IUserRepositoryAggregate {
 		return this.authRepo.updateWebAuthnCredentialName(userId, credentialId, name);
 	}

+	async setWebAuthnCredentialSupersededBy(userId: UserID, credentialId: string, supersededBy: string): Promise<void> {
+		return this.authRepo.setWebAuthnCredentialSupersededBy(userId, credentialId, supersededBy);
+	}
+
 	async deleteWebAuthnCredential(userId: UserID, credentialId: string): Promise<void> {
 		return this.authRepo.deleteWebAuthnCredential(userId, credentialId);
 	}
@@ -26,7 +26,7 @@ const FETCH_WEBAUTHN_CREDENTIALS_FOR_USER_CQL = WebAuthnCredentials.selectCql({
 export class WebAuthnRepository {
 	async listWebAuthnCredentials(userId: UserID): Promise<Array<WebAuthnCredential>> {
 		const credentials = await fetchMany<WebAuthnCredentialRow>(FETCH_WEBAUTHN_CREDENTIALS_CQL, {user_id: userId});
-		return credentials.map((cred) => new WebAuthnCredential(cred));
+		return credentials.filter((cred) => cred.public_key).map((cred) => new WebAuthnCredential(cred));
 	}

 	async getWebAuthnCredential(userId: UserID, credentialId: string): Promise<WebAuthnCredential | null> {
@@ -34,7 +34,7 @@ export class WebAuthnRepository {
 			user_id: userId,
 			credential_id: credentialId,
 		});
-		if (!cred) {
+		if (!cred?.public_key) {
 			return null;
 		}
 		return new WebAuthnCredential(cred);
@@ -47,6 +47,7 @@ export class WebAuthnRepository {
 		counter: bigint,
 		transports: Set<string> | null,
 		name: string,
+		rpId: string | null,
 	): Promise<void> {
 		const credentialData = {
 			user_id: userId,
@@ -58,6 +59,8 @@ export class WebAuthnRepository {
 			created_at: new Date(),
 			last_used_at: null,
 			version: 1 as const,
+			rp_id: rpId,
+			superseded_by: null,
 		};
 		await upsertOne(WebAuthnCredentials.insert(credentialData));
 		await upsertOne(
@@ -101,6 +104,17 @@ export class WebAuthnRepository {
 		);
 	}

+	async setWebAuthnCredentialSupersededBy(userId: UserID, credentialId: string, supersededBy: string): Promise<void> {
+		await upsertOne(
+			WebAuthnCredentials.patchByPk(
+				{user_id: userId, credential_id: credentialId},
+				{
+					superseded_by: Db.set(supersededBy),
+				},
+			),
+		);
+	}
+
 	async deleteWebAuthnCredential(userId: UserID, credentialId: string): Promise<void> {
 		await deleteOneOrMany(
 			WebAuthnCredentials.deleteByPk({
@@ -4,12 +4,13 @@ import type {ApiContext} from '@app/api/ApiContext';
 import * as AuthMfa from '@app/api/auth/AuthMfa';
 import * as AuthPhone from '@app/api/auth/AuthPhone';
 import {requireEmailVerified} from '@app/api/auth/EmailVerificationUtils';
+import {visibleWebAuthnCredentials} from '@app/api/auth/services/PasskeyRelyingParty';
 import type {SudoVerificationResult} from '@app/api/auth/services/SudoVerificationService';
 import type {IGuildRepositoryAggregate} from '@app/api/guild/repositories/IGuildRepositoryAggregate';
 import type {User} from '@app/api/models/User';
 import type {IUserRepository} from '@app/api/user/IUserRepository';
 import * as UserAuth from '@app/api/user/services/UserAuth';
-import {mapUserToPrivateResponse} from '@app/api/user/UserMappers';
+import {mapUserToPrivateResponse, mapWebAuthnCredentialToResponse} from '@app/api/user/UserMappers';
 import {GuildVerificationLevel} from '@fluxer/constants/src/GuildConstants';
 import {UserAuthenticatorTypes} from '@fluxer/constants/src/UserConstants';
 import {PhoneAddNotEligibleError} from '@fluxer/errors/src/domains/auth/PhoneAddNotEligibleError';
@@ -170,17 +171,16 @@ export class UserAuthRequestService {

 	async listWebAuthnCredentials(user: User): Promise<WebAuthnCredentialListResponse> {
 		const credentials = await this.userRepository.listWebAuthnCredentials(user.id);
-		return credentials.map((cred) => ({
-			id: cred.credentialId,
-			name: cred.name,
-			created_at: cred.createdAt.toISOString(),
-			last_used_at: cred.lastUsedAt?.toISOString() ?? null,
-		}));
+		const legacyRpId = this.apiContext.services.config.auth.passkeys.rpId;
+		return visibleWebAuthnCredentials(credentials).map((cred) => mapWebAuthnCredentialToResponse(cred, legacyRpId));
 	}

-	async generateWebAuthnRegistrationOptions(user: User): Promise<WebAuthnChallengeResponse> {
+	async generateWebAuthnRegistrationOptions(
+		user: User,
+		origin: string | undefined,
+	): Promise<WebAuthnChallengeResponse> {
 		requireEmailVerified(user, 'mfa');
-		const options = await AuthMfa.generateWebAuthnRegistrationOptions(this.apiContext, user.id);
+		const options = await AuthMfa.generateWebAuthnRegistrationOptions(this.apiContext, user.id, origin);
 		return this.toWebAuthnChallengeResponse(options);
 	}

@@ -217,8 +217,8 @@ export class UserAuthRequestService {
 		return AuthMfa.getAvailableMfaMethods(this.apiContext, user.id);
 	}

-	async getSudoWebAuthnOptions(user: User): Promise<WebAuthnChallengeResponse> {
-		const options = await AuthMfa.generateWebAuthnOptionsForSudo(this.apiContext, user.id);
+	async getSudoWebAuthnOptions(user: User, origin: string | undefined): Promise<WebAuthnChallengeResponse> {
+		const options = await AuthMfa.generateWebAuthnOptionsForSudo(this.apiContext, user.id, origin);
 		return this.toWebAuthnChallengeResponse(options);
 	}

@@ -20,12 +20,23 @@ import {resolveLimitSafe} from '@app/api/limits/LimitConfigUtils';
 import {createLimitMatchContext} from '@app/api/limits/LimitMatchContextBuilder';
 import type {RequestCache} from '@app/api/middleware/RequestCacheMiddleware';
 import type {Message} from '@app/api/models/Message';
-import type {PushSubscription} from '@app/api/models/PushSubscription';
+import {PushSubscription} from '@app/api/models/PushSubscription';
 import type {IUserAccountRepository} from '@app/api/user/repositories/IUserAccountRepository';
 import type {IUserContentRepository} from '@app/api/user/repositories/IUserContentRepository';
 import {BaseUserUpdatePropagator} from '@app/api/user/services/BaseUserUpdatePropagator';
 import {verifyHarvestDownloadToken} from '@app/api/user/services/HarvestDownloadToken';
 import {buildHarvestDownloadUrl} from '@app/api/user/services/HarvestDownloadUrl';
+import {
+	findInstalledLegacyPushSubscriptionIds,
+	findTargetPushSubscriptionIds,
+	getPushOriginReplacement,
+	getPushSessionPredecessor,
+	markInstalledLegacyPushSubscription,
+	markPushOriginReplaced,
+	markTargetPushSubscription,
+	sameUserAgentFamily,
+	type WebPushOriginKind,
+} from '@app/api/user/services/WebPushOriginReplacement';
 import {UserHarvest} from '@app/api/user/UserHarvestModel';
 import {UserHarvestRepository} from '@app/api/user/UserHarvestRepository';
 import {serializeSelfMessageFilter} from '@app/api/worker/utils/SelfMessageFilterPayload';
@@ -56,6 +67,7 @@ import type {
 import type {SavedMessageStatus} from '@fluxer/schema/src/domains/user/UserResponseSchemas';
 import {snowflakeToDate} from '@fluxer/snowflake/src/Snowflake';
 import {isPubliclyRoutableUrlShape} from '@pkgs/http_client/src/PublicInternetRequestUrlPolicy';
+import type {IKVProvider} from '@pkgs/kv_client/src/IKVProvider';
 import type {IWorkerService} from '@pkgs/worker/src/contracts/IWorkerService';
 import {ms} from 'itty-time';

@@ -159,6 +171,7 @@ export class UserContentService {
 	private readonly gatewayService: IGatewayService;
 	private readonly workerService: IWorkerService<WorkerTaskName>;
 	private readonly snowflakeService: ISnowflakeService;
+	private readonly kv: IKVProvider;

 	constructor(
 		apiContext: ApiContext,
@@ -168,11 +181,12 @@ export class UserContentService {
 		private bulkMessageDeletionQueue: KVBulkMessageDeletionQueueService,
 		private limitConfigService: LimitConfigService,
 	) {
-		const {users, gateway, worker, snowflake} = apiContext.services;
+		const {users, gateway, worker, snowflake, kv} = apiContext.services;
 		this.userRepository = users;
 		this.gatewayService = gateway;
 		this.workerService = worker;
 		this.snowflakeService = snowflake;
+		this.kv = kv;
 		this.updatePropagator = new BaseUserUpdatePropagator({
 			userCacheService,
 			gatewayService: this.gatewayService,
@@ -359,8 +373,10 @@ export class UserContentService {
 			auth: string;
 		};
 		userAgent?: string;
+		originKind?: WebPushOriginKind | null;
+		installedApp?: boolean;
 	}): Promise<PushSubscription> {
-		const {userId, authSessionIdHash, endpoint, keys, userAgent} = params;
+		const {userId, authSessionIdHash, endpoint, keys, userAgent, originKind, installedApp} = params;
 		assertPublicPushEndpoint(endpoint, 'endpoint');
 		const subscriptionId = createWebPushSubscriptionId(endpoint);
 		const data: PushSubscriptionRow = {
@@ -375,11 +391,76 @@ export class UserContentService {
 			app_id: null,
 			provider_environment: null,
 		};
-		const subscription = await this.userRepository.createPushSubscription(data);
+		const subscription = await this.storeWebPushSubscription(data, originKind ?? null, installedApp === true);
 		await this.gatewayService.invalidatePushSubscriptions({userId});
 		return subscription;
 	}

+	private async storeWebPushSubscription(
+		data: PushSubscriptionRow,
+		originKind: WebPushOriginKind | null,
+		installedApp: boolean,
+	): Promise<PushSubscription> {
+		if (originKind === 'legacy' && (await this.isLegacyWebPushReplaced(data, installedApp))) {
+			return new PushSubscription(data);
+		}
+		const subscription = await this.userRepository.createPushSubscription(data);
+		if (originKind === 'legacy' && installedApp) {
+			await this.bestEffortPushOriginWrite(() => markInstalledLegacyPushSubscription(this.kv, data.subscription_id));
+		}
+		if (originKind === 'target') {
+			await this.bestEffortPushOriginWrite(() => this.replaceLegacyWebPushSubscriptions(data, installedApp));
+		}
+		return subscription;
+	}
+
+	private async isLegacyWebPushReplaced(data: PushSubscriptionRow, installedApp: boolean): Promise<boolean> {
+		const sessionIdHash = data.auth_session_id_hash;
+		if (!sessionIdHash) return false;
+		try {
+			const replacement = await getPushOriginReplacement(this.kv, sessionIdHash);
+			return replacement === 'installed' || (replacement === 'browser' && !installedApp);
+		} catch (error) {
+			Logger.warn({error}, 'Failed to read the web push origin replacement');
+			return false;
+		}
+	}
+
+	private async bestEffortPushOriginWrite(write: () => Promise<void>): Promise<void> {
+		try {
+			await write();
+		} catch (error) {
+			Logger.warn({error}, 'Failed to apply the web push origin replacement');
+		}
+	}
+
+	private async replaceLegacyWebPushSubscriptions(data: PushSubscriptionRow, installedApp: boolean): Promise<void> {
+		await markTargetPushSubscription(this.kv, data.subscription_id);
+		const sessionIdHash = data.auth_session_id_hash;
+		if (!sessionIdHash) return;
+		await markPushOriginReplaced(this.kv, sessionIdHash, installedApp ? 'installed' : 'browser');
+		const predecessor = await getPushSessionPredecessor(this.kv, sessionIdHash);
+		const candidates = (await this.userRepository.listPushSubscriptions(data.user_id)).filter(
+			(subscription) =>
+				subscription.platform === WEB_PUSH_PLATFORM &&
+				subscription.endpoint !== data.endpoint &&
+				(subscription.authSessionIdHash === sessionIdHash ||
+					(predecessor !== null &&
+						subscription.authSessionIdHash === predecessor &&
+						sameUserAgentFamily(subscription.userAgent, data.user_agent))),
+		);
+		const candidateIds = candidates.map((subscription) => subscription.subscriptionId);
+		const [targetSubscriptionIds, installedLegacySubscriptionIds] = await Promise.all([
+			findTargetPushSubscriptionIds(this.kv, candidateIds),
+			installedApp ? Promise.resolve(new Set<string>()) : findInstalledLegacyPushSubscriptionIds(this.kv, candidateIds),
+		]);
+		for (const subscription of candidates) {
+			if (targetSubscriptionIds.has(subscription.subscriptionId)) continue;
+			if (installedLegacySubscriptionIds.has(subscription.subscriptionId)) continue;
+			await this.userRepository.deletePushSubscription(data.user_id, subscription.subscriptionId);
+		}
+	}
+
 	async listPushSubscriptions(userId: UserID): Promise<Array<PushSubscription>> {
 		const subscriptions = await this.userRepository.listPushSubscriptions(userId);
 		return subscriptions.filter((subscription) => subscription.platform === WEB_PUSH_PLATFORM);
@@ -400,8 +481,10 @@ export class UserContentService {
 			auth: string;
 		};
 		userAgent?: string;
+		originKind?: WebPushOriginKind | null;
+		installedApp?: boolean;
 	}): Promise<PushSubscription> {
-		const {userId, authSessionIdHash, oldEndpoint, endpoint, keys, userAgent} = params;
+		const {userId, authSessionIdHash, oldEndpoint, endpoint, keys, userAgent, originKind, installedApp} = params;
 		assertPublicPushEndpoint(endpoint, 'endpoint');
 		const oldSubscriptionId = createWebPushSubscriptionId(oldEndpoint);
 		const newSubscriptionId = createWebPushSubscriptionId(endpoint);
@@ -420,7 +503,7 @@ export class UserContentService {
 			app_id: null,
 			provider_environment: null,
 		};
-		const subscription = await this.userRepository.createPushSubscription(data);
+		const subscription = await this.storeWebPushSubscription(data, originKind ?? null, installedApp === true);
 		await this.gatewayService.invalidatePushSubscriptions({userId});
 		return subscription;
 	}
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import type {IKVProvider} from '@pkgs/kv_client/src/IKVProvider';
+import {seconds} from 'itty-time';
+import {uint8ArrayToBase64} from 'uint8array-extras';
+
+export type WebPushOriginKind = 'legacy' | 'target';
+
+export type WebPushOriginReplacement = 'installed' | 'browser';
+
+const WEB_PUSH_ORIGIN_KINDS: ReadonlyMap<string, WebPushOriginKind> = new Map([
+	['https://web.fluxer.app', 'legacy'],
+	['https://web.canary.fluxer.app', 'legacy'],
+	['https://fluxer.com', 'target'],
+	['https://canary.fluxer.com', 'target'],
+]);
+
+const PUSH_ORIGIN_REPLACED_PREFIX = 'push_origin_replaced:';
+const PUSH_SESSION_PREDECESSOR_PREFIX = 'push_session_predecessor:';
+const PUSH_TARGET_SUBSCRIPTION_PREFIX = 'push_target_subscription:';
+const PUSH_INSTALLED_LEGACY_SUBSCRIPTION_PREFIX = 'push_installed_legacy_subscription:';
+const USER_AGENT_VERSION_PATTERN = /\d+(?:[._]\d+)*/g;
+
+export const WEB_PUSH_ORIGIN_RECORD_TTL_SECONDS = seconds('400 days');
+
+export function classifyWebPushOrigin(
+	origin: string | null | undefined,
+	selfHosted: boolean,
+): WebPushOriginKind | null {
+	if (selfHosted || !origin) return null;
+	return WEB_PUSH_ORIGIN_KINDS.get(origin) ?? null;
+}
+
+export function encodePushSessionIdHash(sessionIdHash: Uint8Array): string {
+	return uint8ArrayToBase64(sessionIdHash, {urlSafe: true});
+}
+
+export function sameUserAgentFamily(a: string | null | undefined, b: string | null | undefined): boolean {
+	if (!a || !b) return false;
+	return a.replace(USER_AGENT_VERSION_PATTERN, '') === b.replace(USER_AGENT_VERSION_PATTERN, '');
+}
+
+export async function recordPushSessionPredecessor(
+	kv: IKVProvider,
+	sessionIdHash: string,
+	predecessorSessionIdHash: string,
+): Promise<void> {
+	if (sessionIdHash === predecessorSessionIdHash) return;
+	await kv.setex(
+		`${PUSH_SESSION_PREDECESSOR_PREFIX}${sessionIdHash}`,
+		WEB_PUSH_ORIGIN_RECORD_TTL_SECONDS,
+		predecessorSessionIdHash,
+	);
+}
+
+export async function getPushSessionPredecessor(kv: IKVProvider, sessionIdHash: string): Promise<string | null> {
+	return kv.get(`${PUSH_SESSION_PREDECESSOR_PREFIX}${sessionIdHash}`);
+}
+
+export async function markPushOriginReplaced(
+	kv: IKVProvider,
+	sessionIdHash: string,
+	replacement: WebPushOriginReplacement,
+): Promise<void> {
+	const key = `${PUSH_ORIGIN_REPLACED_PREFIX}${sessionIdHash}`;
+	if (replacement === 'browser' && (await kv.get(key)) === 'installed') return;
+	await kv.setex(key, WEB_PUSH_ORIGIN_RECORD_TTL_SECONDS, replacement);
+}
+
+export async function getPushOriginReplacement(
+	kv: IKVProvider,
+	sessionIdHash: string,
+): Promise<WebPushOriginReplacement | null> {
+	const value = await kv.get(`${PUSH_ORIGIN_REPLACED_PREFIX}${sessionIdHash}`);
+	if (value === null) return null;
+	return value === 'browser' ? 'browser' : 'installed';
+}
+
+async function markSubscription(kv: IKVProvider, prefix: string, subscriptionId: string): Promise<void> {
+	await kv.setex(`${prefix}${subscriptionId}`, WEB_PUSH_ORIGIN_RECORD_TTL_SECONDS, '1');
+}
+
+async function findMarkedSubscriptionIds(
+	kv: IKVProvider,
+	prefix: string,
+	subscriptionIds: Array<string>,
+): Promise<Set<string>> {
+	if (subscriptionIds.length === 0) return new Set();
+	const markers = await kv.mget(...subscriptionIds.map((id) => `${prefix}${id}`));
+	return new Set(subscriptionIds.filter((_, index) => markers[index] !== null));
+}
+
+export async function markTargetPushSubscription(kv: IKVProvider, subscriptionId: string): Promise<void> {
+	await markSubscription(kv, PUSH_TARGET_SUBSCRIPTION_PREFIX, subscriptionId);
+}
+
+export async function findTargetPushSubscriptionIds(
+	kv: IKVProvider,
+	subscriptionIds: Array<string>,
+): Promise<Set<string>> {
+	return findMarkedSubscriptionIds(kv, PUSH_TARGET_SUBSCRIPTION_PREFIX, subscriptionIds);
+}
+
+export async function markInstalledLegacyPushSubscription(kv: IKVProvider, subscriptionId: string): Promise<void> {
+	await markSubscription(kv, PUSH_INSTALLED_LEGACY_SUBSCRIPTION_PREFIX, subscriptionId);
+}
+
+export async function findInstalledLegacyPushSubscriptionIds(
+	kv: IKVProvider,
+	subscriptionIds: Array<string>,
+): Promise<Set<string>> {
+	return findMarkedSubscriptionIds(kv, PUSH_INSTALLED_LEGACY_SUBSCRIPTION_PREFIX, subscriptionIds);
+}
@@ -0,0 +1,383 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import {createAuthHarness, createTestAccount, loginAccount} from '@app/api/auth/tests/AuthTestUtils';
+import {getConfig} from '@app/api/Config';
+import type {ApiTestHarness} from '@app/api/test/ApiTestHarness';
+import {createBuilder, createBuilderWithoutAuth} from '@app/api/test/TestRequestBuilder';
+import {classifyWebPushOrigin, sameUserAgentFamily} from '@app/api/user/services/WebPushOriginReplacement';
+import {listPushSubscriptions} from '@app/api/user/tests/UserTestUtils';
+import {afterAll, afterEach, beforeAll, beforeEach, describe, expect, it, vi} from 'vitest';
+
+const LEGACY_ORIGIN = 'https://web.fluxer.app';
+const TARGET_ORIGIN = 'https://fluxer.com';
+const IPHONE_UA =
+	'Mozilla/5.0 (iPhone; CPU iPhone OS 18_0 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.0 Mobile/15E148 Safari/604.1';
+const IPHONE_UPDATED_UA =
+	'Mozilla/5.0 (iPhone; CPU iPhone OS 18_1 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.1 Mobile/15E148 Safari/604.1';
+const DESKTOP_CHROME_UA =
+	'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/140.0.0.0 Safari/537.36';
+const ANDROID_CHROME_UA =
+	'Mozilla/5.0 (Linux; Android 10; K) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/140.0.0.0 Mobile Safari/537.36';
+
+interface SubscribeOptions {
+	userAgent?: string;
+	installedApp?: boolean;
+}
+
+interface PushSubscribeResponse {
+	subscription_id: string;
+}
+
+interface HandoffInitiateResponse {
+	code: string;
+	poll_secret: string;
+}
+
+interface HandoffStatusResponse {
+	status: 'pending' | 'completed' | 'expired';
+	token?: string;
+}
+
+describe('classifyWebPushOrigin', () => {
+	it.each([
+		{origin: 'https://web.fluxer.app', kind: 'legacy'},
+		{origin: 'https://web.canary.fluxer.app', kind: 'legacy'},
+		{origin: 'https://fluxer.com', kind: 'target'},
+		{origin: 'https://canary.fluxer.com', kind: 'target'},
+		{origin: 'https://fluxer.app', kind: null},
+		{origin: 'https://example.com', kind: null},
+		{origin: undefined, kind: null},
+		{origin: null, kind: null},
+	])('classifies $origin as $kind on the official instance', ({origin, kind}) => {
+		expect(classifyWebPushOrigin(origin, false)).toBe(kind);
+	});
+
+	it('never classifies an origin on a self-hosted instance', () => {
+		expect(classifyWebPushOrigin(LEGACY_ORIGIN, true)).toBeNull();
+		expect(classifyWebPushOrigin(TARGET_ORIGIN, true)).toBeNull();
+	});
+});
+
+describe('sameUserAgentFamily', () => {
+	it('matches the same browser across version updates', () => {
+		expect(sameUserAgentFamily(IPHONE_UA, IPHONE_UPDATED_UA)).toBe(true);
+	});
+
+	it('tells devices and browsers apart', () => {
+		expect(sameUserAgentFamily(DESKTOP_CHROME_UA, ANDROID_CHROME_UA)).toBe(false);
+		expect(sameUserAgentFamily(IPHONE_UA, DESKTOP_CHROME_UA)).toBe(false);
+	});
+
+	it('never matches a missing user agent', () => {
+		expect(sameUserAgentFamily(null, null)).toBe(false);
+		expect(sameUserAgentFamily(IPHONE_UA, undefined)).toBe(false);
+	});
+});
+
+describe('web push origin replacement', () => {
+	let harness: ApiTestHarness;
+	beforeAll(async () => {
+		harness = await createAuthHarness();
+	});
+	beforeEach(async () => {
+		await harness.reset();
+	});
+	afterAll(async () => {
+		await harness?.shutdown();
+	});
+	afterEach(() => {
+		vi.restoreAllMocks();
+	});
+
+	async function subscribeFrom(
+		token: string,
+		origin: string | null,
+		endpoint: string,
+		options: SubscribeOptions = {},
+	): Promise<string> {
+		const builder = createBuilder<PushSubscribeResponse>(harness, token).post('/users/@me/push/subscribe');
+		if (origin) builder.header('Origin', origin);
+		const response = await builder
+			.body({
+				endpoint,
+				keys: {p256dh: 'test-p256dh-key', auth: 'test-auth-key'},
+				user_agent: options.userAgent,
+				installed_app: options.installedApp,
+			})
+			.execute();
+		return response.subscription_id;
+	}
+
+	async function rotateFrom(
+		token: string,
+		origin: string,
+		oldEndpoint: string,
+		endpoint: string,
+		installedApp?: boolean,
+	): Promise<string> {
+		const response = await createBuilder<PushSubscribeResponse>(harness, token)
+			.post('/users/@me/push/rotate')
+			.header('Origin', origin)
+			.body({
+				old_endpoint: oldEndpoint,
+				endpoint,
+				keys: {p256dh: 'test-p256dh-key', auth: 'test-auth-key'},
+				installed_app: installedApp,
+			})
+			.execute();
+		return response.subscription_id;
+	}
+
+	async function listSubscriptionIds(token: string): Promise<Array<string>> {
+		const result = await listPushSubscriptions(harness, token);
+		return result.subscriptions.map((subscription) => subscription.subscription_id).sort();
+	}
+
+	async function pairNewSession(
+		approverToken: string,
+		approverUserId: string,
+		approverOrigin: string,
+		initiatorOrigin: string | null = TARGET_ORIGIN,
+	) {
+		const initiate = createBuilderWithoutAuth<HandoffInitiateResponse>(harness).post('/auth/handoff/initiate');
+		if (initiatorOrigin) initiate.header('Origin', initiatorOrigin);
+		const initiated = await initiate.body(null).execute();
+		await createBuilderWithoutAuth(harness).get(`/auth/handoff/${initiated.code}/info`).execute();
+		await createBuilderWithoutAuth(harness)
+			.post('/auth/handoff/complete')
+			.header('Origin', approverOrigin)
+			.body({code: initiated.code, token: approverToken, user_id: approverUserId})
+			.expect(204)
+			.execute();
+		const completed = await createBuilderWithoutAuth<HandoffStatusResponse>(harness)
+			.post(`/auth/handoff/${initiated.code}/status`)
+			.body({poll_secret: initiated.poll_secret})
+			.execute();
+		expect(completed.status).toBe('completed');
+		return completed.token!;
+	}
+
+	async function withSelfHosted(callback: () => Promise<void>): Promise<void> {
+		const config = getConfig();
+		const original = config.instance.selfHosted;
+		try {
+			config.instance.selfHosted = true;
+			await callback();
+		} finally {
+			config.instance.selfHosted = original;
+		}
+	}
+
+	it('replaces the legacy subscription of the same session when the new origin subscribes', async () => {
+		const account = await createTestAccount(harness);
+		await subscribeFrom(account.token, LEGACY_ORIGIN, 'https://push.example.com/legacy');
+		const target = await subscribeFrom(account.token, TARGET_ORIGIN, 'https://push.example.com/target');
+		expect(await listSubscriptionIds(account.token)).toEqual([target]);
+	});
+
+	it('turns a later legacy subscribe for the replaced session into a no-op', async () => {
+		const account = await createTestAccount(harness);
+		const target = await subscribeFrom(account.token, TARGET_ORIGIN, 'https://push.example.com/target');
+		const legacy = await subscribeFrom(account.token, LEGACY_ORIGIN, 'https://push.example.com/legacy');
+		expect(legacy).toMatch(/^[a-f0-9]{32}$/);
+		expect(legacy).not.toBe(target);
+		expect(await listSubscriptionIds(account.token)).toEqual([target]);
+	});
+
+	it('does not store a legacy rotation for a replaced session', async () => {
+		const account = await createTestAccount(harness);
+		await subscribeFrom(account.token, LEGACY_ORIGIN, 'https://push.example.com/legacy-old');
+		const target = await subscribeFrom(account.token, TARGET_ORIGIN, 'https://push.example.com/target');
+		await rotateFrom(
+			account.token,
+			LEGACY_ORIGIN,
+			'https://push.example.com/legacy-old',
+			'https://push.example.com/legacy-new',
+		);
+		expect(await listSubscriptionIds(account.token)).toEqual([target]);
+	});
+
+	it('keeps legacy subscriptions working until the new origin subscribes', async () => {
+		const account = await createTestAccount(harness);
+		const first = await subscribeFrom(account.token, LEGACY_ORIGIN, 'https://push.example.com/legacy-a');
+		const second = await subscribeFrom(account.token, LEGACY_ORIGIN, 'https://push.example.com/legacy-b');
+		expect(await listSubscriptionIds(account.token)).toEqual([first, second].sort());
+	});
+
+	it('leaves subscriptions from other sessions alone', async () => {
+		const account = await createTestAccount(harness);
+		const other = await loginAccount(harness, account);
+		const otherLegacy = await subscribeFrom(other.token, LEGACY_ORIGIN, 'https://push.example.com/other-legacy');
+		const target = await subscribeFrom(account.token, TARGET_ORIGIN, 'https://push.example.com/target');
+		expect(await listSubscriptionIds(account.token)).toEqual([otherLegacy, target].sort());
+	});
+
+	it('never removes another new-origin subscription of the same session', async () => {
+		const account = await createTestAccount(harness);
+		const first = await subscribeFrom(account.token, TARGET_ORIGIN, 'https://push.example.com/target-a');
+		const second = await subscribeFrom(account.token, 'https://canary.fluxer.com', 'https://push.example.com/target-b');
+		expect(await listSubscriptionIds(account.token)).toEqual([first, second].sort());
+	});
+
+	it('treats unclassified rows as legacy without ever skipping an unclassified subscribe', async () => {
+		const account = await createTestAccount(harness);
+		const unknown = await subscribeFrom(account.token, null, 'https://push.example.com/no-origin');
+		const target = await subscribeFrom(account.token, TARGET_ORIGIN, 'https://push.example.com/target');
+		expect(await listSubscriptionIds(account.token)).toEqual([target]);
+		const legacyAfter = await subscribeFrom(account.token, null, 'https://push.example.com/no-origin');
+		expect(legacyAfter).toBe(unknown);
+		expect(await listSubscriptionIds(account.token)).toEqual([unknown, target].sort());
+	});
+
+	it('replaces the approving legacy session on the same device once a paired session subscribes', async () => {
+		const account = await createTestAccount(harness);
+		const approver = await loginAccount(harness, account);
+		const approverLegacy = 'https://push.example.com/approver-legacy';
+		await subscribeFrom(approver.token, LEGACY_ORIGIN, approverLegacy, {userAgent: IPHONE_UA, installedApp: true});
+		const pairedToken = await pairNewSession(approver.token, approver.userId, LEGACY_ORIGIN);
+		const paired = await subscribeFrom(pairedToken, TARGET_ORIGIN, 'https://push.example.com/paired', {
+			userAgent: IPHONE_UPDATED_UA,
+			installedApp: true,
+		});
+		expect(await listSubscriptionIds(approver.token)).toEqual([paired]);
+	});
+
+	it('never silences the approving session for good', async () => {
+		const account = await createTestAccount(harness);
+		const approver = await loginAccount(harness, account);
+		const approverLegacy = 'https://push.example.com/approver-legacy';
+		await subscribeFrom(approver.token, LEGACY_ORIGIN, approverLegacy, {userAgent: IPHONE_UA});
+		const pairedToken = await pairNewSession(approver.token, approver.userId, LEGACY_ORIGIN);
+		const paired = await subscribeFrom(pairedToken, TARGET_ORIGIN, 'https://push.example.com/paired', {
+			userAgent: IPHONE_UA,
+		});
+		const restored = await subscribeFrom(approver.token, LEGACY_ORIGIN, approverLegacy, {userAgent: IPHONE_UA});
+		expect(await listSubscriptionIds(approver.token)).toEqual([paired, restored].sort());
+	});
+
+	it('leaves the approving session alone when it runs on another device', async () => {
+		const account = await createTestAccount(harness);
+		const approver = await loginAccount(harness, account);
+		const approverLegacy = await subscribeFrom(approver.token, LEGACY_ORIGIN, 'https://push.example.com/desktop', {
+			userAgent: DESKTOP_CHROME_UA,
+			installedApp: true,
+		});
+		const pairedToken = await pairNewSession(approver.token, approver.userId, LEGACY_ORIGIN);
+		const paired = await subscribeFrom(pairedToken, TARGET_ORIGIN, 'https://push.example.com/phone', {
+			userAgent: ANDROID_CHROME_UA,
+			installedApp: true,
+		});
+		expect(await listSubscriptionIds(approver.token)).toEqual([approverLegacy, paired].sort());
+		const desktopAgain = await subscribeFrom(approver.token, LEGACY_ORIGIN, 'https://push.example.com/desktop', {
+			userAgent: DESKTOP_CHROME_UA,
+			installedApp: true,
+		});
+		expect(desktopAgain).toBe(approverLegacy);
+		expect(await listSubscriptionIds(approver.token)).toEqual([approverLegacy, paired].sort());
+	});
+
+	it.each([
+		{label: 'the approval came from the new origin', approverOrigin: TARGET_ORIGIN, initiatorOrigin: TARGET_ORIGIN},
+		{label: 'the new session did not start on the new origin', approverOrigin: LEGACY_ORIGIN, initiatorOrigin: null},
+		{
+			label: 'the new session started on the old origin',
+			approverOrigin: LEGACY_ORIGIN,
+			initiatorOrigin: LEGACY_ORIGIN,
+		},
+	])('does not link sessions when $label', async ({approverOrigin, initiatorOrigin}) => {
+		const account = await createTestAccount(harness);
+		const approver = await loginAccount(harness, account);
+		const approverSubscription = await subscribeFrom(
+			approver.token,
+			LEGACY_ORIGIN,
+			'https://push.example.com/approver-legacy',
+			{userAgent: IPHONE_UA},
+		);
+		const pairedToken = await pairNewSession(approver.token, approver.userId, approverOrigin, initiatorOrigin);
+		const paired = await subscribeFrom(pairedToken, TARGET_ORIGIN, 'https://push.example.com/paired', {
+			userAgent: IPHONE_UA,
+		});
+		expect(await listSubscriptionIds(approver.token)).toEqual([approverSubscription, paired].sort());
+	});
+
+	it('completes the approval when the predecessor link cannot be written', async () => {
+		const account = await createTestAccount(harness);
+		const approver = await loginAccount(harness, account);
+		const setex = harness.kvProvider.setex.bind(harness.kvProvider);
+		vi.spyOn(harness.kvProvider, 'setex').mockImplementation(async (key, ttl, value) => {
+			if (key.startsWith('push_session_predecessor:')) throw new Error('kv down');
+			return setex(key, ttl, value);
+		});
+		const pairedToken = await pairNewSession(approver.token, approver.userId, LEGACY_ORIGIN);
+		expect(pairedToken).toBeTruthy();
+	});
+
+	it('stores a subscribe when the replacement marker cannot be read or written', async () => {
+		const account = await createTestAccount(harness);
+		const get = harness.kvProvider.get.bind(harness.kvProvider);
+		vi.spyOn(harness.kvProvider, 'get').mockImplementation(async (key) => {
+			if (key.startsWith('push_origin_replaced:')) throw new Error('kv down');
+			return get(key);
+		});
+		const target = await subscribeFrom(account.token, TARGET_ORIGIN, 'https://push.example.com/target');
+		const legacy = await subscribeFrom(account.token, LEGACY_ORIGIN, 'https://push.example.com/legacy');
+		expect(await listSubscriptionIds(account.token)).toEqual([legacy, target].sort());
+	});
+
+	it('keeps an installed legacy app subscribed when only a browser tab moved', async () => {
+		const account = await createTestAccount(harness);
+		const installed = await subscribeFrom(account.token, LEGACY_ORIGIN, 'https://push.example.com/legacy-app', {
+			userAgent: DESKTOP_CHROME_UA,
+			installedApp: true,
+		});
+		const target = await subscribeFrom(account.token, TARGET_ORIGIN, 'https://push.example.com/target-tab', {
+			userAgent: DESKTOP_CHROME_UA,
+		});
+		expect(await listSubscriptionIds(account.token)).toEqual([installed, target].sort());
+		const rotated = await rotateFrom(
+			account.token,
+			LEGACY_ORIGIN,
+			'https://push.example.com/legacy-app',
+			'https://push.example.com/legacy-app-2',
+			true,
+		);
+		expect(await listSubscriptionIds(account.token)).toEqual([rotated, target].sort());
+		await subscribeFrom(account.token, LEGACY_ORIGIN, 'https://push.example.com/legacy-tab', {
+			userAgent: DESKTOP_CHROME_UA,
+		});
+		expect(await listSubscriptionIds(account.token)).toEqual([rotated, target].sort());
+	});
+
+	it('replaces an installed legacy app once the new app is installed', async () => {
+		const account = await createTestAccount(harness);
+		await subscribeFrom(account.token, LEGACY_ORIGIN, 'https://push.example.com/legacy-app', {
+			userAgent: DESKTOP_CHROME_UA,
+			installedApp: true,
+		});
+		await subscribeFrom(account.token, TARGET_ORIGIN, 'https://push.example.com/target-tab', {
+			userAgent: DESKTOP_CHROME_UA,
+		});
+		const targetApp = await subscribeFrom(account.token, TARGET_ORIGIN, 'https://push.example.com/target-app', {
+			userAgent: DESKTOP_CHROME_UA,
+			installedApp: true,
+		});
+		const ids = await listSubscriptionIds(account.token);
+		expect(ids).toContain(targetApp);
+		expect(ids).toHaveLength(2);
+		await subscribeFrom(account.token, LEGACY_ORIGIN, 'https://push.example.com/legacy-app', {
+			userAgent: DESKTOP_CHROME_UA,
+			installedApp: true,
+		});
+		expect(await listSubscriptionIds(account.token)).toEqual(ids);
+	});
+
+	it('does nothing new on a self-hosted instance', async () => {
+		await withSelfHosted(async () => {
+			const account = await createTestAccount(harness);
+			const legacy = await subscribeFrom(account.token, LEGACY_ORIGIN, 'https://push.example.com/legacy');
+			const target = await subscribeFrom(account.token, TARGET_ORIGIN, 'https://push.example.com/target');
+			const legacyAgain = await subscribeFrom(account.token, LEGACY_ORIGIN, 'https://push.example.com/legacy-2');
+			expect(await listSubscriptionIds(account.token)).toEqual([legacy, target, legacyAgain].sort());
+		});
+	});
+});
@@ -10,6 +10,11 @@ function getInviteEndpointBase(): string {
 	return `${url.hostname}${url.pathname.replace(/\/+$/, '')}`;
 }

+function getWebAppHostsPattern(): string {
+	const hostnames = new Set(Config.endpoints.webAppOrigins.map((origin) => new URL(origin).hostname));
+	return [...hostnames].map((hostname) => RegexUtils.escapeRegex(hostname)).join('|');
+}
+
 function getInvitePattern(): RegExp {
 	if (!_invitePattern) {
 		_invitePattern = new RegExp(
@@ -18,7 +23,7 @@ function getInvitePattern(): RegExp {
 				'(?:',
 				`${RegexUtils.escapeRegex(getInviteEndpointBase())}(?:\\/#)?\\/(?!invite\\/)([a-zA-Z0-9\\-]{2,32})(?![a-zA-Z0-9\\-])`,
 				'|',
-				`${RegexUtils.escapeRegex(new URL(Config.endpoints.webApp).hostname)}(?:\\/#)?\\/invite\\/([a-zA-Z0-9\\-]{2,32})(?![a-zA-Z0-9\\-])`,
+				`(?:${getWebAppHostsPattern()})(?:\\/#)?\\/invite\\/([a-zA-Z0-9\\-]{2,32})(?![a-zA-Z0-9\\-])`,
 				')',
 			].join(''),
 			'gi',
@@ -8,7 +8,7 @@ import * as InviteUtils from '@app/api/utils/InviteUtils';
 import {URL_REGEX} from '@fluxer/constants/src/Core';
 import * as idna from 'idna-uts46-hx';

-const CLIENT_ROUTE_PATH_PREFIXES = ['/channels/', '/theme/'];
+const CLIENT_ROUTE_PATH_PREFIXES = ['/channels/', '/theme/', '/invite/', '/gift/', '/oauth2/', '/users/'];

 interface ExcludedLinkBase {
 	hostname: string;
@@ -19,12 +19,14 @@ function normalizeHostname(hostname: string | undefined) {
 	return hostname?.trim().toLowerCase() || '';
 }

-function getWebAppHostname() {
-	try {
-		return new URL(Config.endpoints.webApp).hostname;
-	} catch {
-		return '';
-	}
+function getWebAppHostnames(): Array<string> {
+	return Config.endpoints.webAppOrigins.flatMap((origin) => {
+		try {
+			return [new URL(origin).hostname];
+		} catch {
+			return [];
+		}
+	});
 }

 function endpointLinkBase(endpoint: string): ExcludedLinkBase | null {
@@ -45,7 +47,7 @@ function getExcludedLinkBases(): Array<ExcludedLinkBase> {
 			endpointLinkBase(Config.endpoints.invite),
 			endpointLinkBase(Config.endpoints.gift),
 		];
-		for (const hostname of [getWebAppHostname(), Config.hosts.marketing]) {
+		for (const hostname of [...getWebAppHostnames(), Config.hosts.marketing]) {
 			for (const pathPrefix of CLIENT_ROUTE_PATH_PREFIXES) {
 				bases.push({hostname: normalizeHostname(hostname), pathPrefix});
 			}
@@ -13,7 +13,7 @@ import {
 	getSubscriptionPremiumPeriodEnd,
 	getSubscriptionStartDate,
 } from '@app/api/stripe/StripeSubscriptionPeriod';
-import {createPremiumClearPatch, getEffectivePremiumUntil} from '@app/api/user/UserHelpers';
+import {clearPerksSanitizedFlag, createPremiumClearPatch, getEffectivePremiumUntil} from '@app/api/user/UserHelpers';
 import {mapUserToPrivateResponse} from '@app/api/user/UserMappers';
 import {getWorkerDependencies} from '@app/api/worker/WorkerContext';
 import {PremiumFlags, UserPremiumTypes} from '@fluxer/constants/src/UserConstants';
@@ -73,6 +73,10 @@ function buildStripePremiumRepairPatch(user: User, subscription: Stripe.Subscrip
 	if (user.stripeSubscriptionId !== subscription.id) {
 		patch.stripe_subscription_id = subscription.id;
 	}
+	const clearedPremiumFlags = clearPerksSanitizedFlag(user.premiumFlags);
+	if (user.premiumFlags !== clearedPremiumFlags) {
+		patch.premium_flags = clearedPremiumFlags;
+	}
 	if (subscriptionCustomerId && user.stripeCustomerId !== subscriptionCustomerId) {
 		patch.stripe_customer_id = subscriptionCustomerId;
 	}
@@ -10,6 +10,7 @@ import {NoopLogger} from '@app/api/test/mocks/NoopLogger';
 import type {UserRepository} from '@app/api/user/repositories/UserRepository';
 import processPremiumStateReconciliationQueue from '@app/api/worker/tasks/ProcessPremiumStateReconciliationQueue';
 import {clearWorkerDependencies, setWorkerDependenciesForTest} from '@app/api/worker/WorkerContext';
+import {PremiumFlags} from '@fluxer/constants/src/UserConstants';
 import type {WorkerTaskHelpers} from '@pkgs/worker/src/contracts/WorkerTask';
 import type Stripe from 'stripe';
 import {afterEach, describe, expect, test} from 'vitest';
@@ -48,6 +49,28 @@ function createCancelledSubscription(endedAtMs: number): Stripe.Subscription {
 	} as unknown as Stripe.Subscription;
 }

+function createActiveSubscription(periodEndMs: number): Stripe.Subscription {
+	return {
+		id: 'sub_test',
+		status: 'active',
+		customer: 'cus_test',
+		ended_at: null,
+		canceled_at: null,
+		cancel_at: null,
+		cancel_at_period_end: false,
+		trial_end: null,
+		start_date: Math.floor((Date.now() - 200 * ONE_DAY_MS) / 1000),
+		items: {
+			data: [
+				{
+					current_period_end: Math.floor(periodEndMs / 1000),
+					price: {recurring: {interval: 'month'}},
+				},
+			],
+		},
+	} as unknown as Stripe.Subscription;
+}
+
 function createPaidInvoice(periodEndMs: number): Stripe.Invoice {
 	return {
 		id: 'in_test',
@@ -299,4 +322,27 @@ describe('processPremiumStateReconciliationQueue', () => {
 		expect(patches[0].premium_until).toBeNull();
 		expect(patches[0].premium_since).toBeNull();
 	});
+	test('clears the perks-sanitized latch once the subscription is active again', async () => {
+		const queueService = createQueueService();
+		await queueService.enqueueUser(USER_ID, new Date(Date.now() - 1000));
+
+		const periodEndMs = Math.floor((Date.now() + 20 * ONE_DAY_MS) / 1000) * 1000;
+		const user = createPremiumUser({
+			premium_until: new Date(periodEndMs),
+			premium_flags: PremiumFlags.PERKS_SANITIZED,
+		});
+		const {userRepository, patches, extras} = createCapturingDeps(user);
+
+		setWorkerDependenciesForTest({
+			premiumStateReconciliationQueueService: queueService,
+			stripe: createStripeStub(createActiveSubscription(periodEndMs), []),
+			userRepository,
+			...extras,
+		});
+
+		await processPremiumStateReconciliationQueue({}, createHelpers());
+
+		expect(patches).toHaveLength(1);
+		expect(patches[0].premium_flags).toBe(0);
+	});
 });
@@ -433,6 +433,7 @@ export default () => {
 			staticFilesPlugin({
 				staticCdnEndpoint: normalizedStaticCdnEndpoint,
 				fontsDir: path.join(MONOREPO_ROOT, 'packages', 'fonts'),
+				wasmCratesDir: path.join(ROOT_DIR, 'rust'),
 			}),
 			new DefinePlugin({
 				__FLUXER_PRECACHE_MANIFEST__: JSON.stringify([]),
@@ -0,0 +1,28 @@
+BSD 3-Clause License
+
+Copyright (c) 2026, Alexandre Bury
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+3. Neither the name of the copyright holder nor the names of its
+   contributors may be used to endorse or promote products derived from
+   this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
@@ -0,0 +1,32 @@
+The auto-generated bindings are under the 3-clause BSD license:
+
+BSD License
+
+For Zstandard software
+
+Copyright (c) Meta Platforms, Inc. and affiliates. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification,
+are permitted provided that the following conditions are met:
+
+ * Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+ * Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+ * Neither the name Facebook, nor Meta, nor the names of its contributors may
+   be used to endorse or promote products derived from this software without
+   specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
@@ -0,0 +1,30 @@
+BSD License
+
+For Zstandard software
+
+Copyright (c) Meta Platforms, Inc. and affiliates. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification,
+are permitted provided that the following conditions are met:
+
+ * Redistributions of source code must retain the above copyright notice, this
+   list of conditions and the following disclaimer.
+
+ * Redistributions in binary form must reproduce the above copyright notice,
+   this list of conditions and the following disclaimer in the documentation
+   and/or other materials provided with the distribution.
+
+ * Neither the name Facebook, nor Meta, nor the names of its contributors may
+   be used to endorse or promote products derived from this software without
+   specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
@@ -0,0 +1,12 @@
+# libfluxcore licenses
+
+`libfluxcore_bg.wasm` is built from this crate and bundled into the app. It
+contains third-party code that keeps its upstream license.
+
+| Component | Source | License |
+| --- | --- | --- |
+| Zstandard 1.5.7 | Vendored by the `zstd-sys` 2.1.0 crate | BSD-3-Clause, see `LICENSE-ZSTD.txt` (Zstandard is dual licensed, Fluxer uses it under BSD-3-Clause) |
+| `zstd-sys` 2.1.0 | Rust bindings, build script and WebAssembly libc shim | BSD-3-Clause, see `LICENSE-ZSTD-SYS.txt` |
+| `zstd` 0.14.0 | Rust wrapper | BSD-3-Clause, see `LICENSE-ZSTD-RS.txt` |
+
+No Fluxer license notice grants rights to third-party trademarks or brand names.
@@ -16,6 +16,22 @@ pub fn is_animated_image_bytes(input: &[u8]) -> bool {
    false
 }

+pub fn sniff_image_format_bytes(input: &[u8]) -> u8 {
+    if is_png(input) {
+        1
+    } else if is_gif(input) {
+        2
+    } else if is_webp(input) {
+        3
+    } else if is_avif_file(input) {
+        4
+    } else if input.starts_with(&[0xff, 0xd8, 0xff]) {
+        5
+    } else {
+        0
+    }
+}
+
 fn is_gif(input: &[u8]) -> bool {
    input.starts_with(b"GIF89a") || input.starts_with(b"GIF87a")
 }
@@ -35,7 +51,16 @@ fn is_avif_file(input: &[u8]) -> bool {
 }

 fn has_avif_anim(input: &[u8]) -> bool {
-    is_avif_file(input) && &input[8..12] == b"avis"
+    if !is_avif_file(input) {
+        return false;
+    }
+    if &input[8..12] == b"avis" {
+        return true;
+    }
+    let box_end = read_u32_be(input, 0).map_or(0, |size| (size as usize).min(input.len()));
+    input
+        .get(16..box_end)
+        .is_some_and(|brands| brands.as_chunks::<4>().0.contains(b"avis"))
 }

 fn has_apng_actl(input: &[u8]) -> bool {
@@ -243,13 +268,53 @@ mod tests {

    #[test]
    fn detects_avif_sequence_brand() {
-        let avif = b"\x00\x00\x00\x18ftypavif\x00\x00\x00\x00avis";
-        assert!(!is_animated_image_bytes(avif));
+        let still = b"\x00\x00\x00\x18ftypavif\x00\x00\x00\x00mif1miaf";
+        assert!(!is_animated_image_bytes(still));

        let avis = b"\x00\x00\x00\x18ftypavis\x00\x00\x00\x00avif";
        assert!(is_animated_image_bytes(avis));
    }

+    #[test]
+    fn detects_avis_among_compatible_brands() {
+        let compat = b"\x00\x00\x00\x1cftypavif\x00\x00\x00\x00mif1avismsf1";
+        assert!(is_animated_image_bytes(compat));
+
+        let outside_ftyp = b"\x00\x00\x00\x14ftypavif\x00\x00\x00\x00mif1avis";
+        assert!(!is_animated_image_bytes(outside_ftyp));
+
+        let truncated = b"\x00\x00\x00\x40ftypavif\x00\x00\x00\x00mif1av";
+        assert!(!is_animated_image_bytes(truncated));
+    }
+
+    #[test]
+    fn sniffs_image_formats_from_magic_bytes() {
+        assert_eq!(sniff_image_format_bytes(b""), 0);
+        assert_eq!(sniff_image_format_bytes(b"<svg xmlns"), 0);
+        assert_eq!(
+            sniff_image_format_bytes(b"\x89PNG\r\n\x1a\n\0\0\0\rIHDR"),
+            1
+        );
+        assert_eq!(sniff_image_format_bytes(b"GIF89a\x01\x00"), 2);
+        assert_eq!(sniff_image_format_bytes(b"GIF87a\x01\x00"), 2);
+        assert_eq!(sniff_image_format_bytes(b"RIFF\x04\0\0\0WEBPVP8 "), 3);
+        assert_eq!(sniff_image_format_bytes(b"RIFF\x04\0\0\0WAVEfmt "), 0);
+        assert_eq!(
+            sniff_image_format_bytes(b"\x00\x00\x00\x18ftypavif\x00\x00\x00\x00"),
+            4
+        );
+        assert_eq!(
+            sniff_image_format_bytes(b"\x00\x00\x00\x18ftypavis\x00\x00\x00\x00"),
+            4
+        );
+        assert_eq!(
+            sniff_image_format_bytes(b"\x00\x00\x00\x18ftypheic\x00\x00\x00\x00"),
+            0
+        );
+        assert_eq!(sniff_image_format_bytes(b"\xff\xd8\xff\xe0\x00\x10JFIF"), 5);
+        assert_eq!(sniff_image_format_bytes(b"\xff\xd8"), 0);
+    }
+
    #[test]
    fn rejects_truncated_chunks_without_panicking() {
        assert!(!is_animated_image_bytes(
@@ -5,8 +5,8 @@ mod rgba;
 mod zstd_frame;
 mod zstd_stream;

-use formats::is_animated_image_bytes;
-use rgba::{TransformRequest, crop_rotate_rgba_alloc};
+use formats::{is_animated_image_bytes, sniff_image_format_bytes};
+use rgba::{TransformRequest, crop_rotate_rgba_alloc, crop_rotate_rgba_into};
 use wasm_bindgen::prelude::*;

 #[wasm_bindgen]
@@ -40,6 +40,39 @@ pub fn crop_rotate_rgba_raw(
    .map_err(|error| JsValue::from_str(error.message()))
 }

+#[wasm_bindgen]
+#[allow(clippy::too_many_arguments)]
+pub fn crop_rotate_rgba_into_buffer(
+    input: &[u8],
+    output: &mut [u8],
+    src_width: u32,
+    src_height: u32,
+    x: u32,
+    y: u32,
+    width: u32,
+    height: u32,
+    rotation_deg: u32,
+    output_width: u32,
+    output_height: u32,
+) -> Result<(), JsValue> {
+    crop_rotate_rgba_into(
+        input,
+        output,
+        TransformRequest {
+            src_width,
+            src_height,
+            x,
+            y,
+            width,
+            height,
+            rotation_deg,
+            resize_width: output_width,
+            resize_height: output_height,
+        },
+    )
+    .map_err(|error| JsValue::from_str(error.message()))
+}
+
 #[wasm_bindgen]
 pub fn decompress_zstd_frame(input: &[u8]) -> Result<Vec<u8>, JsValue> {
    zstd_frame::decompress(input).map_err(zstd_error_to_js)
@@ -106,6 +139,11 @@ pub fn is_animated_image(input: &[u8]) -> bool {
    is_animated_image_bytes(input)
 }

+#[wasm_bindgen]
+pub fn sniff_image_format(input: &[u8]) -> u8 {
+    sniff_image_format_bytes(input)
+}
+
 fn optional_dimension_to_abi(value: Option<u32>) -> u32 {
    value.filter(|dimension| *dimension > 0).unwrap_or(u32::MAX)
 }
@@ -22,6 +22,7 @@ pub struct TransformRequest {
 pub enum TransformError {
    InvalidDimensions,
    InvalidRgbaLength,
+    InvalidOutputLength,
    EmptyCrop,
    EmptyTarget,
    ImageTooLarge,
@@ -33,6 +34,7 @@ impl TransformError {
        match self {
            Self::InvalidDimensions => "invalid RGBA dimensions",
            Self::InvalidRgbaLength => "RGBA input length does not match dimensions",
+            Self::InvalidOutputLength => "RGBA output length does not match target dimensions",
            Self::EmptyCrop => "Crop area is empty",
            Self::EmptyTarget => "Target dimensions are empty",
            Self::ImageTooLarge => "Image is too large to crop",
@@ -75,12 +77,7 @@ pub fn crop_rotate_rgba_alloc(
    input: &[u8],
    request: TransformRequest,
 ) -> Result<Vec<u8>, TransformError> {
-    let geometry = output_geometry(request)?;
-    let expected_len = rgba_byte_len(request.src_width, request.src_height, 0)?;
-    if input.len() != expected_len {
-        return Err(TransformError::InvalidRgbaLength);
-    }
-
+    let geometry = checked_geometry(input, request)?;
    let output_len = rgba_byte_len(
        geometry.target_width,
        geometry.target_height,
@@ -89,8 +86,45 @@ pub fn crop_rotate_rgba_alloc(
    let mut output = try_zeroed_vec(output_len)?;
    write_u32_le(&mut output, 0, geometry.target_width);
    write_u32_le(&mut output, 4, geometry.target_height);
+    write_transformed(
+        input,
+        &mut output[RGBA_RESULT_HEADER_BYTES..],
+        request,
+        geometry,
+    );
+    Ok(output)
+}

-    let dst = &mut output[RGBA_RESULT_HEADER_BYTES..];
+pub fn crop_rotate_rgba_into(
+    input: &[u8],
+    output: &mut [u8],
+    request: TransformRequest,
+) -> Result<(), TransformError> {
+    let geometry = checked_geometry(input, request)?;
+    if output.len() != rgba_byte_len(geometry.target_width, geometry.target_height, 0)? {
+        return Err(TransformError::InvalidOutputLength);
+    }
+    write_transformed(input, output, request, geometry);
+    Ok(())
+}
+
+fn checked_geometry(
+    input: &[u8],
+    request: TransformRequest,
+) -> Result<OutputGeometry, TransformError> {
+    let geometry = output_geometry(request)?;
+    if input.len() != rgba_byte_len(request.src_width, request.src_height, 0)? {
+        return Err(TransformError::InvalidRgbaLength);
+    }
+    Ok(geometry)
+}
+
+fn write_transformed(
+    input: &[u8],
+    dst: &mut [u8],
+    request: TransformRequest,
+    geometry: OutputGeometry,
+) {
    if geometry.target_width == geometry.base_width
        && geometry.target_height == geometry.base_height
    {
@@ -98,8 +132,6 @@ pub fn crop_rotate_rgba_alloc(
    } else {
        copy_rotated_with_nearest_resize(input, dst, request, geometry);
    }
-
-    Ok(output)
 }

 fn output_geometry(request: TransformRequest) -> Result<OutputGeometry, TransformError> {
@@ -463,6 +495,30 @@ mod tests {
        assert!(crop_rotate_rgba_alloc(&rgba(&[1, 2, 3, 4]), empty_target).is_ok());
    }

+    #[test]
+    fn into_writes_the_same_pixels_as_alloc() {
+        let input = rgba(&[1, 2, 3, 4, 5, 6]);
+        for rotation_deg in [0, 90, 180, 270] {
+            let mut transform = request(2, 3);
+            transform.rotation_deg = rotation_deg;
+            transform.resize_width = 5;
+            transform.resize_height = 4;
+            let expected = crop_rotate_rgba_alloc(&input, transform).unwrap();
+            let mut output = vec![0xaa; 5 * 4 * RGBA_BYTES_PER_PIXEL];
+            crop_rotate_rgba_into(&input, &mut output, transform).unwrap();
+            assert_eq!(output, payload(&expected));
+        }
+    }
+
+    #[test]
+    fn into_rejects_an_output_of_the_wrong_length() {
+        let mut output = vec![0; 3 * RGBA_BYTES_PER_PIXEL];
+        assert_eq!(
+            crop_rotate_rgba_into(&rgba(&[1, 2, 3, 4]), &mut output, request(2, 2)).unwrap_err(),
+            TransformError::InvalidOutputLength
+        );
+    }
+
    proptest! {
        #[test]
        fn identity_transform_preserves_pixels(width in 1u32..16, height in 1u32..16) {
@@ -0,0 +1,160 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "bumpalo"
+version = "3.20.3"
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+
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+dependencies = [
+ "find-msvc-tools",
+ "shlex",
+]
+
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+
+[[package]]
+name = "libfluxwebp"
+version = "0.1.0"
+dependencies = [
+ "libwebp-sys",
+ "wasm-bindgen",
+]
+
+[[package]]
+name = "libwebp-sys"
+version = "0.14.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
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+ "cc",
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+ "pkg-config",
+]
+
+[[package]]
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+source = "registry+https://github.com/rust-lang/crates.io-index"
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+
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+
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+dependencies = [
+ "proc-macro2",
+]
+
+[[package]]
+name = "rustversion"
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf54715a573b99ac80df0bc206da022bcd442c974952c7b9720069370852e21f"
+
+[[package]]
+name = "shlex"
+version = "2.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f8fadd59c855ef2080decdef8ff161eb6661b86933c9d82e5ba29dc602a55aba"
+
+[[package]]
+name = "syn"
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8593e8e72159ed2257d083c7a454a85cbf854f37a0966d8d483aff8c8a3ebcee"
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+ "proc-macro2",
+ "quote",
+ "unicode-ident",
+]
+
+[[package]]
+name = "unicode-ident"
+version = "1.0.26"
+source = "registry+https://github.com/rust-lang/crates.io-index"
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+
+[[package]]
+name = "wasm-bindgen"
+version = "0.2.128"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "aecb87a33d3b0c5e3b7aa46336eaf486cffafbd281b195e4c8b80d50df2351bf"
+dependencies = [
+ "cfg-if",
+ "once_cell",
+ "rustversion",
+ "wasm-bindgen-macro",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-macro"
+version = "0.2.128"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a690d511e3c1a8b3a55e33511e3c2c00c78415cd23650f32b808627f5696b9ed"
+dependencies = [
+ "quote",
+ "wasm-bindgen-macro-support",
+]
+
+[[package]]
+name = "wasm-bindgen-macro-support"
+version = "0.2.128"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "411e4887f0071ef2d2164a9d5fdf2d20efbef78fccd3a78b0c10a1dc5295e48a"
+dependencies = [
+ "bumpalo",
+ "proc-macro2",
+ "quote",
+ "syn",
+ "wasm-bindgen-shared",
+]
+
+[[package]]
+name = "wasm-bindgen-shared"
+version = "0.2.128"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "81941cd78d0c92026c33e5e01312845a4cb1e9af3407f9134b100dd03144103e"
+dependencies = [
+ "unicode-ident",
+]
@@ -0,0 +1,22 @@
+[package]
+name = "libfluxwebp"
+version = "0.1.0"
+edition = "2024"
+license = "AGPL-3.0-or-later"
+publish = false
+
+[lib]
+crate-type = ["cdylib"]
+
+[dependencies]
+wasm-bindgen = "=0.2.128"
+libwebp-sys = {version = "=0.14.4", default-features = false}
+
+[profile.release]
+codegen-units = 1
+lto = true
+opt-level = "z"
+panic = "abort"
+strip = true
+
+[workspace]
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) the libwebp-sys authors (XianYou, Kornel Lesiński and contributors)
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
@@ -0,0 +1,30 @@
+Copyright (c) 2010, Google Inc. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+  * Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimer.
+
+  * Redistributions in binary form must reproduce the above copyright
+    notice, this list of conditions and the following disclaimer in
+    the documentation and/or other materials provided with the
+    distribution.
+
+  * Neither the name of Google nor the names of its contributors may
+    be used to endorse or promote products derived from this software
+    without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
@@ -0,0 +1,16 @@
+# libfluxwebp licenses
+
+`libfluxwebp_bg.wasm` and `libfluxwebp_simd_bg.wasm` are built from this crate
+and bundled into the app. They contain third-party code that keeps its upstream
+license.
+
+| Component | Source | License |
+| --- | --- | --- |
+| libwebp 1.6.0 | Vendored by the `libwebp-sys` 0.14.4 crate | BSD-3-Clause, see `LICENSE-LIBWEBP.txt`, with the additional patent grant in `PATENTS-LIBWEBP.txt` |
+| `libwebp-sys` 0.14.4 | Rust bindings and build script | MIT, see `LICENSE-LIBWEBP-SYS.txt` |
+| `simd/xmmintrin.h`, `simd/emmintrin.h` | Emscripten 4.0.15 SSE compatibility headers | MIT or University of Illinois/NCSA, see `simd/LICENSE` |
+
+The SIMD build compiles libwebp's SSE2 code paths through the Emscripten
+headers, unmodified. The headers in `shim/` and `src/shim.rs` are Fluxer code.
+
+No Fluxer license notice grants rights to third-party trademarks or brand names.
@@ -0,0 +1,23 @@
+Additional IP Rights Grant (Patents)
+------------------------------------
+
+"These implementations" means the copyrightable works that implement the WebM
+codecs distributed by Google as part of the WebM Project.
+
+Google hereby grants to you a perpetual, worldwide, non-exclusive, no-charge,
+royalty-free, irrevocable (except as stated in this section) patent license to
+make, have made, use, offer to sell, sell, import, transfer, and otherwise
+run, modify and propagate the contents of these implementations of WebM, where
+such license applies only to those patent claims, both currently owned by
+Google and acquired in the future, licensable by Google that are necessarily
+infringed by these implementations of WebM. This grant does not include claims
+that would be infringed only as a consequence of further modification of these
+implementations. If you or your agent or exclusive licensee institute or order
+or agree to the institution of patent litigation or any other patent
+enforcement activity against any entity (including a cross-claim or
+counterclaim in a lawsuit) alleging that any of these implementations of WebM
+or any code incorporated within any of these implementations of WebM
+constitute direct or contributory patent infringement, or inducement of
+patent infringement, then any patent rights granted to you under this License
+for these implementations of WebM shall terminate as of the date such
+litigation is filed.
@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+#ifndef FLUXWEBP_ASSERT_H
+#define FLUXWEBP_ASSERT_H
+#define assert(expr) ((void)0)
+#endif
@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+#ifndef FLUXWEBP_INTTYPES_H
+#define FLUXWEBP_INTTYPES_H
+#include <stdint.h>
+#endif
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+#ifndef FLUXWEBP_MATH_H
+#define FLUXWEBP_MATH_H
+double fluxwebp_shim_pow(double x, double y);
+double fluxwebp_shim_log(double x);
+float fluxwebp_shim_expf(float x);
+double fluxwebp_shim_log10(double x);
+float fluxwebp_shim_logf(float x);
+double fluxwebp_shim_round(double x);
+#define pow(x, y) fluxwebp_shim_pow(x, y)
+#define log(x) fluxwebp_shim_log(x)
+#define expf(x) fluxwebp_shim_expf(x)
+#define log10(x) fluxwebp_shim_log10(x)
+#define logf(x) fluxwebp_shim_logf(x)
+#define round(x) fluxwebp_shim_round(x)
+#define fabs(x) __builtin_fabs(x)
+#define floor(x) __builtin_floor(x)
+#define ceil(x) __builtin_ceil(x)
+#define sqrt(x) __builtin_sqrt(x)
+#define sqrtf(x) __builtin_sqrtf(x)
+#define rint(x) __builtin_rint(x)
+#define rintf(x) __builtin_rintf(x)
+#define fabsf(x) __builtin_fabsf(x)
+#define floorf(x) __builtin_floorf(x)
+#define ceilf(x) __builtin_ceilf(x)
+#define isnan(x) __builtin_isnan(x)
+#define isinf(x) __builtin_isinf(x)
+#define lrint(x) ((long)__builtin_rint(x))
+#define llrint(x) ((long long)__builtin_rint(x))
+#define lrintf(x) ((long)__builtin_rintf(x))
+#define llrintf(x) ((long long)__builtin_rintf(x))
+#endif
@@ -0,0 +1,50 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+#ifndef FLUXWEBP_STDIO_H
+#define FLUXWEBP_STDIO_H
+#include <stddef.h>
+#include <stdarg.h>
+typedef struct FluxWebpFile FILE;
+#define stderr ((FILE*)0)
+#define stdout ((FILE*)0)
+#define fprintf(f, ...) ((void)0)
+#define printf(...) ((void)0)
+#define fflush(f) ((void)0)
+
+static inline void fluxwebp_shim_put(char* buf, size_t cap, size_t* n, char c) {
+  if (*n + 1 < cap) buf[*n] = c;
+  (*n)++;
+}
+
+static inline int snprintf(char* buf, size_t cap, const char* fmt, ...) {
+  va_list ap;
+  size_t n = 0;
+  va_start(ap, fmt);
+  for (; *fmt; fmt++) {
+    if (*fmt != '%') {
+      fluxwebp_shim_put(buf, cap, &n, *fmt);
+      continue;
+    }
+    fmt++;
+    if (*fmt == 's') {
+      const char* s = va_arg(ap, const char*);
+      while (s && *s) fluxwebp_shim_put(buf, cap, &n, *s++);
+    } else if (*fmt == 'd') {
+      int v = va_arg(ap, int);
+      char tmp[12];
+      int i = 0;
+      unsigned int u = v < 0 ? 0u - (unsigned int)v : (unsigned int)v;
+      if (v < 0) fluxwebp_shim_put(buf, cap, &n, '-');
+      do { tmp[i++] = (char)('0' + u % 10); u /= 10; } while (u);
+      while (i) fluxwebp_shim_put(buf, cap, &n, tmp[--i]);
+    } else if (*fmt == '%') {
+      fluxwebp_shim_put(buf, cap, &n, '%');
+    } else {
+      break;
+    }
+  }
+  va_end(ap);
+  if (cap) buf[n < cap ? n : cap - 1] = '\0';
+  return (int)n;
+}
+#endif
@@ -0,0 +1,16 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+#ifndef FLUXWEBP_STDLIB_H
+#define FLUXWEBP_STDLIB_H
+#include <stddef.h>
+void* fluxwebp_shim_malloc(size_t size);
+void* fluxwebp_shim_calloc(size_t nmemb, size_t size);
+void fluxwebp_shim_free(void* ptr);
+void fluxwebp_shim_qsort(void* base, size_t nitems, size_t size, int (*compar)(const void*, const void*));
+#define malloc(size) fluxwebp_shim_malloc(size)
+#define calloc(nmemb, size) fluxwebp_shim_calloc(nmemb, size)
+#define free(ptr) fluxwebp_shim_free(ptr)
+#define qsort(base, nitems, size, compar) fluxwebp_shim_qsort(base, nitems, size, compar)
+#define abort() __builtin_trap()
+static inline int abs(int x) { return x < 0 ? -x : x; }
+#endif
@@ -0,0 +1,11 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+#ifndef FLUXWEBP_STRING_H
+#define FLUXWEBP_STRING_H
+#include <stddef.h>
+#define memcpy(d, s, n) __builtin_memcpy(d, s, n)
+#define memmove(d, s, n) __builtin_memmove(d, s, n)
+#define memset(d, c, n) __builtin_memset(d, c, n)
+#define memcmp(a, b, n) __builtin_memcmp(a, b, n)
+#define strlen(s) __builtin_strlen(s)
+#endif
@@ -0,0 +1,102 @@
+Emscripten is available under 2 licenses, the MIT license and the
+University of Illinois/NCSA Open Source License.
+
+Both are permissive open source licenses, with little if any
+practical difference between them.
+
+The reason for offering both is that (1) the MIT license is
+well-known, while (2) the University of Illinois/NCSA Open Source
+License allows Emscripten's code to be integrated upstream into
+LLVM, which uses that license, should the opportunity arise.
+
+The full text of both licenses follows.
+
+==============================================================================
+
+Copyright (c) 2010-2014 Emscripten authors, see AUTHORS file.
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+
+==============================================================================
+
+Copyright (c) 2010-2014 Emscripten authors, see AUTHORS file.
+All rights reserved.
+
+Permission is hereby granted, free of charge, to any person obtaining a
+copy of this software and associated documentation files (the
+"Software"), to deal with the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+    Redistributions of source code must retain the above copyright
+    notice, this list of conditions and the following disclaimers.
+
+    Redistributions in binary form must reproduce the above
+    copyright notice, this list of conditions and the following disclaimers
+    in the documentation and/or other materials provided with the
+    distribution.
+
+    Neither the names of Mozilla,
+    nor the names of its contributors may be used to endorse
+    or promote products derived from this Software without specific prior
+    written permission. 
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE FOR
+ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+SOFTWARE OR THE USE OR OTHER DEALINGS WITH THE SOFTWARE.
+
+==============================================================================
+
+This program uses portions of Node.js source code located in src/library_path.js,
+in accordance with the terms of the MIT license. Node's license follows:
+
+    """
+        Copyright Joyent, Inc. and other Node contributors. All rights reserved.
+        Permission is hereby granted, free of charge, to any person obtaining a copy
+        of this software and associated documentation files (the "Software"), to
+        deal in the Software without restriction, including without limitation the
+        rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+        sell copies of the Software, and to permit persons to whom the Software is
+        furnished to do so, subject to the following conditions:
+
+        The above copyright notice and this permission notice shall be included in
+        all copies or substantial portions of the Software.
+
+        THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+        IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+        FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+        AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+        LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+        FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+        IN THE SOFTWARE.
+    """
+
+The musl libc project is bundled in this repo, and it has the MIT license, see
+system/lib/libc/musl/COPYRIGHT
+
+The third_party/ subdirectory contains code with other licenses. None of it is
+used by default, but certain options use it (e.g., the optional closure compiler
+flag will run closure compiler from third_party/).
+
@@ -0,0 +1,714 @@
+/*
+ * Copyright 2020 The Emscripten Authors.  All rights reserved.
+ * Emscripten is available under two separate licenses, the MIT license and the
+ * University of Illinois/NCSA Open Source License.  Both these licenses can be
+ * found in the LICENSE file.
+ */
+#ifndef __emscripten_xmmintrin_h__
+#define __emscripten_xmmintrin_h__
+
+#include <wasm_simd128.h>
+
+#include <limits.h>
+#include <math.h>
+#include <string.h>
+
+#ifndef __SSE__
+#error "SSE instruction set not enabled"
+#endif
+
+#ifdef WASM_SIMD_COMPAT_SLOW
+#define DIAGNOSE_SLOW diagnose_if(1, "Instruction emulated via slow path.", "warning")
+#else
+#define DIAGNOSE_SLOW
+#endif
+
+// Emscripten SIMD support doesn't support MMX/float32x2/__m64.
+// However, we support loading and storing 2-vectors, so
+// recognize the type at least.
+typedef float __m64 __attribute__((__vector_size__(8), __aligned__(8)));
+typedef __f32x4 __m128;
+typedef v128_t __m128i;
+
+#define __f32x4_shuffle(__a, __b, __c0, __c1, __c2, __c3)                   \
+  ((v128_t)(__builtin_shufflevector((__f32x4)(__a), (__f32x4)(__b), __c0,   \
+                                    __c1, __c2, __c3)))
+
+// This is defined as a macro because __builtin_shufflevector requires its
+// mask argument to be a compile-time constant.
+#define _mm_shuffle_ps(__a, __b, __mask) __extension__ ({ \
+  ((__m128)__f32x4_shuffle(__a, __b, \
+                           (((__mask) >> 0) & 0x3) + 0, \
+                           (((__mask) >> 2) & 0x3) + 0, \
+                           (((__mask) >> 4) & 0x3) + 4, \
+                           (((__mask) >> 6) & 0x3) + 4)); })
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_set_ps(float __z, float __y, float __x, float __w)
+{
+  return (__m128)wasm_f32x4_make(__w, __x, __y, __z);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_setr_ps(float __z, float __y, float __x, float __w)
+{
+  return (__m128)wasm_f32x4_make(__z, __y, __x, __w);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_set_ss(float __w)
+{
+  return (__m128)wasm_f32x4_make(__w, 0, 0, 0);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_set_ps1(float __w)
+{
+  return (__m128)wasm_f32x4_splat(__w);
+}
+
+#define _mm_set1_ps _mm_set_ps1
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_setzero_ps(void)
+{
+  return (__m128)wasm_f32x4_const(0.f, 0.f, 0.f, 0.f);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_load_ps(const float *__p)
+{
+  return *(__m128*)__p;
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_loadl_pi(__m128 __a, const void /*__m64*/ *__p)
+{
+  return (__m128)wasm_v128_load64_lane(__p, (v128_t)__a, 0);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_loadh_pi(__m128 __a, const void /*__m64*/ *__p)
+{
+  return (__m128)wasm_v128_load64_lane(__p, (v128_t)__a, 1);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_loadr_ps(const float *__p)
+{
+  __m128 __v = _mm_load_ps(__p);
+  return (__m128)__f32x4_shuffle(__v, __v, 3, 2, 1, 0);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_loadu_ps(const float *__p)
+{
+  return (__m128)wasm_v128_load(__p);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_load_ps1(const float *__p)
+{
+  return (__m128)wasm_v32x4_load_splat(__p);
+}
+#define _mm_load1_ps _mm_load_ps1
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_load_ss(const float *__p)
+{
+  return (__m128)wasm_v128_load32_zero(__p);
+}
+
+static __inline__ void __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_storel_pi(__m64 *__p, __m128 __a)
+{
+  wasm_v128_store64_lane((void*)__p, (v128_t)__a, 0);
+}
+
+static __inline__ void __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_storeh_pi(__m64 *__p, __m128 __a)
+{
+  wasm_v128_store64_lane((void*)__p, (v128_t)__a, 1);
+}
+
+static __inline__ void __attribute__((__always_inline__, __nodebug__))
+_mm_store_ps(float *__p, __m128 __a)
+{
+  *(__m128 *)__p = __a;
+}
+// No NTA cache hint available.
+#define _mm_stream_ps _mm_store_ps
+
+#define _MM_HINT_T0 3
+#define _MM_HINT_T1 2
+#define _MM_HINT_T2 1
+#define _MM_HINT_NTA 0
+// No prefetch available, dummy it out.
+static __inline__ void __attribute__((__always_inline__, __nodebug__))
+_mm_prefetch(const void *__p, int __i)
+{
+  ((void)__p);
+  ((void)__i);
+}
+
+static __inline__ void __attribute__((__always_inline__, __nodebug__))
+_mm_sfence(void)
+{
+  // Wasm/SharedArrayBuffer memory model is sequentially consistent.
+  // Perhaps a future version of the spec can provide a related fence.
+  __sync_synchronize();
+}
+
+#define _MM_SHUFFLE(w, z, y, x) (((w) << 6) | ((z) << 4) | ((y) << 2) | (x))
+
+static __inline__ void __attribute__((__always_inline__, __nodebug__))
+_mm_storer_ps(float *__p, __m128 __a)
+{
+  _mm_store_ps(__p, _mm_shuffle_ps(__a, __a, _MM_SHUFFLE(0, 1, 2, 3)));
+}
+
+static __inline__ void __attribute__((__always_inline__, __nodebug__))
+_mm_store_ps1(float *__p, __m128 __a)
+{
+  _mm_store_ps(__p, _mm_shuffle_ps(__a, __a, _MM_SHUFFLE(0, 0, 0, 0)));
+}
+#define _mm_store1_ps _mm_store_ps1
+
+static __inline__ void __attribute__((__always_inline__, __nodebug__))
+_mm_store_ss(float *__p, __m128 __a)
+{
+  wasm_v128_store32_lane((void*)__p, (v128_t)__a, 0);
+}
+
+static __inline__ void __attribute__((__always_inline__, __nodebug__))
+_mm_storeu_ps(float *__p, __m128 __a)
+{
+  struct __unaligned {
+    __m128 __v;
+  } __attribute__((__packed__, __may_alias__));
+  ((struct __unaligned *)__p)->__v = __a;
+}
+
+static __inline__ int __attribute__((__always_inline__, __nodebug__))
+_mm_movemask_ps(__m128 __a)
+{
+  return (int)wasm_i32x4_bitmask((v128_t)__a);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_move_ss(__m128 __a, __m128 __b)
+{
+  return (__m128)__f32x4_shuffle(__a, __b, 4, 1, 2, 3);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_add_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)wasm_f32x4_add((v128_t)__a, (v128_t)__b);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_add_ss(__m128 __a, __m128 __b)
+{
+  return _mm_move_ss(__a, _mm_add_ps(__a, __b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_sub_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)wasm_f32x4_sub((v128_t)__a, (v128_t)__b);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_sub_ss(__m128 __a, __m128 __b)
+{
+  return _mm_move_ss(__a, _mm_sub_ps(__a, __b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_mul_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)wasm_f32x4_mul((v128_t)__a, (v128_t)__b);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_mul_ss(__m128 __a, __m128 __b)
+{
+  return _mm_move_ss(__a, _mm_mul_ps(__a, __b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_div_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)wasm_f32x4_div((v128_t)__a, (v128_t)__b);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_div_ss(__m128 __a, __m128 __b)
+{
+  return _mm_move_ss(__a, _mm_div_ps(__a, __b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_min_ps(__m128 __a, __m128 __b)
+{
+//  return (__m128)wasm_f32x4_pmin((v128_t)__a, (v128_t)__b); // TODO: Migrate to this, once it works in VMs
+  return (__m128)wasm_v128_bitselect((v128_t)__a, (v128_t)__b, (v128_t)wasm_f32x4_lt((v128_t)__a, (v128_t)__b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_min_ss(__m128 __a, __m128 __b)
+{
+  return _mm_move_ss(__a, _mm_min_ps(__a, __b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_max_ps(__m128 __a, __m128 __b)
+{
+//  return (__m128)wasm_f32x4_pmax((v128_t)__a, (v128_t)__b); // TODO: Migrate to this, once it works in VMs
+  return (__m128)wasm_v128_bitselect((v128_t)__a, (v128_t)__b, (v128_t)wasm_f32x4_gt((v128_t)__a, (v128_t)__b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_max_ss(__m128 __a, __m128 __b)
+{
+  return _mm_move_ss(__a, _mm_max_ps(__a, __b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_rcp_ps(__m128 __a)
+{
+    return (__m128)wasm_f32x4_div((v128_t)_mm_set1_ps(1.0f), (v128_t)__a);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_rcp_ss(__m128 __a)
+{
+  return _mm_move_ss(__a, _mm_rcp_ps(__a));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_sqrt_ps(__m128 __a)
+{
+  return (__m128)wasm_f32x4_sqrt((v128_t)__a);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_sqrt_ss(__m128 __a)
+{
+  return _mm_move_ss(__a, _mm_sqrt_ps(__a));
+}
+
+#define _mm_rsqrt_ps(__a) _mm_rcp_ps(_mm_sqrt_ps((__a)))
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_rsqrt_ss(__m128 __a)
+{
+  return _mm_move_ss(__a, _mm_rsqrt_ps(__a));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_unpackhi_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)__f32x4_shuffle(__a, __b, 2, 6, 3, 7);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_unpacklo_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)__f32x4_shuffle(__a, __b, 0, 4, 1, 5);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_movehl_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)__f32x4_shuffle(__a, __b, 6, 7, 2, 3);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_movelh_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)__f32x4_shuffle(__a, __b, 0, 1, 4, 5);
+}
+
+#define _MM_TRANSPOSE4_PS(row0, row1, row2, row3) \
+  do { \
+    __m128 __row0 = (row0); \
+    __m128 __row1 = (row1); \
+    __m128 __row2 = (row2); \
+    __m128 __row3 = (row3); \
+    __m128 __tmp0 = _mm_unpacklo_ps(__row0, __row1); \
+    __m128 __tmp1 = _mm_unpackhi_ps(__row0, __row1); \
+    __m128 __tmp2 = _mm_unpacklo_ps(__row2, __row3); \
+    __m128 __tmp3 = _mm_unpackhi_ps(__row2, __row3); \
+    (row0) = _mm_movelh_ps(__tmp0, __tmp2); \
+    (row1) = _mm_movehl_ps(__tmp2, __tmp0); \
+    (row2) = _mm_movelh_ps(__tmp1, __tmp3); \
+    (row3) = _mm_movehl_ps(__tmp3, __tmp1); \
+  } while (0)
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_cmplt_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)wasm_f32x4_lt((v128_t)__a, (v128_t)__b);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_cmplt_ss(__m128 __a, __m128 __b)
+{
+  return _mm_move_ss(__a, _mm_cmplt_ps(__a, __b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_cmple_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)wasm_f32x4_le((v128_t)__a, (v128_t)__b);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_cmple_ss(__m128 __a, __m128 __b)
+{
+  return _mm_move_ss(__a, _mm_cmple_ps(__a, __b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_cmpeq_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)wasm_f32x4_eq((v128_t)__a, (v128_t)__b);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_cmpeq_ss(__m128 __a, __m128 __b)
+{
+  return _mm_move_ss(__a, _mm_cmpeq_ps(__a, __b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_cmpge_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)wasm_f32x4_ge((v128_t)__a, (v128_t)__b);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_cmpge_ss(__m128 __a, __m128 __b)
+{
+  return _mm_move_ss(__a, _mm_cmpge_ps(__a, __b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_cmpgt_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)wasm_f32x4_gt((v128_t)__a, (v128_t)__b);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_cmpgt_ss(__m128 __a, __m128 __b)
+{
+  return _mm_move_ss(__a, _mm_cmpgt_ps(__a, __b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW)) _mm_cmpord_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)wasm_v128_and(wasm_f32x4_eq((v128_t)__a, (v128_t)__a),
+                               wasm_f32x4_eq((v128_t)__b, (v128_t)__b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW)) _mm_cmpord_ss(__m128 __a, __m128 __b)
+{
+  return _mm_move_ss(__a, _mm_cmpord_ps(__a, __b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW)) _mm_cmpunord_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)wasm_v128_or(wasm_f32x4_ne((v128_t)__a, (v128_t)__a),
+                              wasm_f32x4_ne((v128_t)__b, (v128_t)__b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW)) _mm_cmpunord_ss(__m128 __a, __m128 __b)
+{
+  return _mm_move_ss(__a, _mm_cmpunord_ps(__a, __b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_and_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)wasm_v128_and((v128_t)__a, (v128_t)__b);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_andnot_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)wasm_v128_andnot((v128_t)__b, (v128_t)__a);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_or_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)wasm_v128_or((v128_t)__a, (v128_t)__b);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_xor_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)wasm_v128_xor((v128_t)__a, (v128_t)__b);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_cmpneq_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)wasm_f32x4_ne((v128_t)__a, (v128_t)__b);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_cmpneq_ss(__m128 __a, __m128 __b)
+{
+  return _mm_move_ss(__a, _mm_cmpneq_ps(__a, __b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_cmpnge_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)wasm_v128_not((v128_t)_mm_cmpge_ps(__a, __b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_cmpnge_ss(__m128 __a, __m128 __b)
+{
+  return _mm_move_ss(__a, _mm_cmpnge_ps(__a, __b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_cmpngt_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)wasm_v128_not((v128_t)_mm_cmpgt_ps(__a, __b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_cmpngt_ss(__m128 __a, __m128 __b)
+{
+  return _mm_move_ss(__a, _mm_cmpngt_ps(__a, __b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_cmpnle_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)wasm_v128_not((v128_t)_mm_cmple_ps(__a, __b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_cmpnle_ss(__m128 __a, __m128 __b)
+{
+  return _mm_move_ss(__a, _mm_cmpnle_ps(__a, __b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_cmpnlt_ps(__m128 __a, __m128 __b)
+{
+  return (__m128)wasm_v128_not((v128_t)_mm_cmplt_ps(__a, __b));
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_cmpnlt_ss(__m128 __a, __m128 __b)
+{
+  return _mm_move_ss(__a, _mm_cmpnlt_ps(__a, __b));
+}
+
+static __inline__ int __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_comieq_ss(__m128 __a, __m128 __b)
+{
+  return wasm_f32x4_extract_lane((v128_t)__a, 0) == wasm_f32x4_extract_lane((v128_t)__b, 0);
+}
+
+static __inline__ int __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_comige_ss(__m128 __a, __m128 __b)
+{
+  return wasm_f32x4_extract_lane((v128_t)__a, 0) >= wasm_f32x4_extract_lane((v128_t)__b, 0);
+}
+
+static __inline__ int __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_comigt_ss(__m128 __a, __m128 __b)
+{
+  return wasm_f32x4_extract_lane((v128_t)__a, 0) > wasm_f32x4_extract_lane((v128_t)__b, 0);
+}
+
+static __inline__ int __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_comile_ss(__m128 __a, __m128 __b)
+{
+  return wasm_f32x4_extract_lane((v128_t)__a, 0) <= wasm_f32x4_extract_lane((v128_t)__b, 0);
+}
+
+static __inline__ int __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_comilt_ss(__m128 __a, __m128 __b)
+{
+  return wasm_f32x4_extract_lane((v128_t)__a, 0) < wasm_f32x4_extract_lane((v128_t)__b, 0);
+}
+
+static __inline__ int __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_comineq_ss(__m128 __a, __m128 __b)
+{
+  return wasm_f32x4_extract_lane((v128_t)__a, 0) != wasm_f32x4_extract_lane((v128_t)__b, 0);
+}
+
+static __inline__ int __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_ucomieq_ss(__m128 __a, __m128 __b)
+{
+  return wasm_f32x4_extract_lane((v128_t)__a, 0) == wasm_f32x4_extract_lane((v128_t)__b, 0);
+}
+
+static __inline__ int __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_ucomige_ss(__m128 __a, __m128 __b)
+{
+  return wasm_f32x4_extract_lane((v128_t)__a, 0) >= wasm_f32x4_extract_lane((v128_t)__b, 0);
+}
+
+static __inline__ int __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_ucomigt_ss(__m128 __a, __m128 __b)
+{
+  return wasm_f32x4_extract_lane((v128_t)__a, 0) > wasm_f32x4_extract_lane((v128_t)__b, 0);
+}
+
+static __inline__ int __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_ucomile_ss(__m128 __a, __m128 __b)
+{
+  return wasm_f32x4_extract_lane((v128_t)__a, 0) <= wasm_f32x4_extract_lane((v128_t)__b, 0);
+}
+
+static __inline__ int __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_ucomilt_ss(__m128 __a, __m128 __b)
+{
+  return wasm_f32x4_extract_lane((v128_t)__a, 0) < wasm_f32x4_extract_lane((v128_t)__b, 0);
+}
+
+static __inline__ int __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_ucomineq_ss(__m128 __a, __m128 __b)
+{
+  return wasm_f32x4_extract_lane((v128_t)__a, 0) != wasm_f32x4_extract_lane((v128_t)__b, 0);
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_cvtsi32_ss(__m128 __a, int __b)
+{
+  __f32x4 __v = (__f32x4)__a;
+  __v[0] = (float)__b;
+  return (__m128)__v;
+}
+#define _mm_cvt_si2ss _mm_cvtsi32_ss
+
+static __inline__ int __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW)) _mm_cvtss_si32(__m128 __a)
+{
+  float e = ((__f32x4)__a)[0];
+  if (e < 2147483648.0f && e >= -2147483648.0f && (lrint(e) != 0 || fabsf(e) < 2.f))
+    return lrint(e);
+  else
+    return (int)0x80000000;
+}
+#define _mm_cvt_ss2si _mm_cvtss_si32
+
+static __inline__ int __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW)) _mm_cvttss_si32(__m128 __a)
+{
+  float e = ((__f32x4)__a)[0];
+  if (e < 2147483648.0f && e >= -2147483648.0f && (lrint(e) != 0 || fabsf(e) < 2.f))
+    return (int)e;
+  else
+    return (int)0x80000000;
+}
+#define _mm_cvtt_ss2si _mm_cvttss_si32
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_cvtsi64_ss(__m128 __a, long long __b)
+{
+  __f32x4 __v = (__f32x4)__a;
+  __v[0] = (float)__b;
+  return (__m128)__v;
+}
+
+static __inline__ long long __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_cvtss_si64(__m128 __a)
+{
+  float e = ((__f32x4)__a)[0];
+  long long x = llrintf(e);
+  if (e <= LLONG_MAX && e >= LLONG_MIN && (x != 0 || fabsf(e) < 2.f))
+    return x;
+  else
+    return 0x8000000000000000LL;
+}
+
+static __inline__ long long __attribute__((__always_inline__, __nodebug__, DIAGNOSE_SLOW))
+_mm_cvttss_si64(__m128 __a)
+{
+  float e = ((__f32x4)__a)[0];
+  long long x = llrintf(e);
+  if (e <= LLONG_MAX && e >= LLONG_MIN && (x != 0 || fabsf(e) < 2.f))
+    return (long long)e;
+  else
+    return 0x8000000000000000LL;
+}
+
+static __inline__ float __attribute__((__always_inline__, __nodebug__))
+_mm_cvtss_f32(__m128 __a)
+{
+  return (float)((__f32x4)__a)[0];
+}
+
+#define _mm_malloc(__size, __align) memalign((__align), (__size))
+#define _mm_free free
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_undefined()
+{
+  __m128 val;
+  return val;
+}
+
+static __inline__ __m128 __attribute__((__always_inline__, __nodebug__))
+_mm_undefined_ps()
+{
+  __m128 val;
+  return val;
+}
+
+#define _MM_EXCEPT_MASK       0x003f
+#define _MM_EXCEPT_INVALID    0x0001
+#define _MM_EXCEPT_DENORM     0x0002
+#define _MM_EXCEPT_DIV_ZERO   0x0004
+#define _MM_EXCEPT_OVERFLOW   0x0008
+#define _MM_EXCEPT_UNDERFLOW  0x0010
+#define _MM_EXCEPT_INEXACT    0x0020
+
+#define _MM_MASK_MASK         0x1f80
+#define _MM_MASK_INVALID      0x0080
+#define _MM_MASK_DENORM       0x0100
+#define _MM_MASK_DIV_ZERO     0x0200
+#define _MM_MASK_OVERFLOW     0x0400
+#define _MM_MASK_UNDERFLOW    0x0800
+#define _MM_MASK_INEXACT      0x1000
+
+#define _MM_ROUND_MASK        0x6000
+#define _MM_ROUND_NEAREST     0x0000
+#define _MM_ROUND_DOWN        0x2000
+#define _MM_ROUND_UP          0x4000
+#define _MM_ROUND_TOWARD_ZERO 0x6000
+
+#define _MM_FLUSH_ZERO_MASK   0x8000
+#define _MM_FLUSH_ZERO_ON     0x8000
+#define _MM_FLUSH_ZERO_OFF    0x0000
+
+static __inline__ int __attribute__((__always_inline__, __nodebug__))
+_mm_getcsr()
+{
+  return _MM_MASK_INEXACT | _MM_MASK_DENORM | _MM_MASK_DIV_ZERO | _MM_MASK_OVERFLOW | _MM_MASK_UNDERFLOW | _MM_MASK_INVALID
+    | _MM_ROUND_NEAREST | _MM_FLUSH_ZERO_OFF;
+}
+
+#define _MM_GET_EXCEPTION_STATE() (_mm_getcsr() & _MM_EXCEPT_MASK)
+#define _MM_GET_EXCEPTION_MASK() (_mm_getcsr() & _MM_MASK_MASK)
+#define _MM_GET_ROUNDING_MODE() (_mm_getcsr() & _MM_ROUND_MASK)
+#define _MM_GET_FLUSH_ZERO_MODE() (_mm_getcsr() & _MM_FLUSH_ZERO_MASK)
+
+// Unavailable functions:
+// void _MM_SET_EXCEPTION_STATE(unsigned int __a);
+// void _MM_SET_EXCEPTION_MASK(unsigned int __a);
+// void _MM_GET_ROUNDING_MODE(unsigned int __a);
+// void _MM_GET_FLUSH_ZERO_MODE(unsigned int __a);
+
+#endif /* __emscripten_xmmintrin_h__ */
@@ -0,0 +1,327 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+#[cfg(all(target_arch = "wasm32", target_os = "unknown"))]
+mod shim;
+
+use libwebp_sys as ffi;
+use std::ffi::CStr;
+use std::ptr;
+use wasm_bindgen::prelude::*;
+
+const DEMUX_ABI: i32 = ffi::WEBP_DEMUX_ABI_VERSION as i32;
+const MUX_ABI: i32 = ffi::WEBP_MUX_ABI_VERSION as i32;
+const ENCODER_ABI: i32 = ffi::WEBP_ENCODER_ABI_VERSION as i32;
+const DECODER_ABI: i32 = ffi::WEBP_DECODER_ABI_VERSION as i32;
+const LOSSLESS_FORMAT: i32 = 2;
+
+fn webp_data(bytes: &[u8]) -> ffi::WebPData {
+    ffi::WebPData {
+        bytes: bytes.as_ptr(),
+        size: bytes.len(),
+    }
+}
+
+#[wasm_bindgen]
+pub fn webp_probe(bytes: &[u8]) -> Result<Box<[u32]>, JsError> {
+    let data = webp_data(bytes);
+    let dmux = unsafe { ffi::WebPDemuxInternal(&data, 0, ptr::null_mut(), DEMUX_ABI) };
+    if dmux.is_null() {
+        return Err(JsError::new("webp demux failed"));
+    }
+    let get = |feature| unsafe { ffi::WebPDemuxGetI(dmux, feature) };
+    let width = get(ffi::WebPFormatFeature::WEBP_FF_CANVAS_WIDTH);
+    let height = get(ffi::WebPFormatFeature::WEBP_FF_CANVAS_HEIGHT);
+    let frame_count = get(ffi::WebPFormatFeature::WEBP_FF_FRAME_COUNT);
+    let loop_count = get(ffi::WebPFormatFeature::WEBP_FF_LOOP_COUNT);
+    let flags = get(ffi::WebPFormatFeature::WEBP_FF_FORMAT_FLAGS);
+    let has_alpha = flags & ffi::WebPFeatureFlags::ALPHA_FLAG as u32 != 0;
+    let all_lossless = unsafe { all_frames_lossless(dmux) };
+    unsafe { ffi::WebPDemuxDelete(dmux) };
+    Ok(Box::new([
+        width,
+        height,
+        frame_count,
+        loop_count,
+        has_alpha as u32,
+        all_lossless as u32,
+    ]))
+}
+
+unsafe fn all_frames_lossless(dmux: *const ffi::WebPDemuxer) -> bool {
+    unsafe {
+        let mut iter: ffi::WebPIterator = std::mem::zeroed();
+        if ffi::WebPDemuxGetFrame(dmux, 1, &mut iter) == 0 {
+            return false;
+        }
+        let mut lossless = true;
+        loop {
+            let mut features: ffi::WebPBitstreamFeatures = std::mem::zeroed();
+            let status = ffi::WebPGetFeaturesInternal(
+                iter.fragment.bytes,
+                iter.fragment.size,
+                &mut features,
+                DECODER_ABI,
+            );
+            if status != ffi::VP8StatusCode::VP8_STATUS_OK || features.format != LOSSLESS_FORMAT {
+                lossless = false;
+                break;
+            }
+            if ffi::WebPDemuxNextFrame(&mut iter) == 0 {
+                break;
+            }
+        }
+        ffi::WebPDemuxReleaseIterator(&mut iter);
+        lossless
+    }
+}
+
+#[wasm_bindgen]
+pub struct AnimDecoder {
+    dec: *mut ffi::WebPAnimDecoder,
+    _bytes: Box<[u8]>,
+    frame: *mut u8,
+    timestamp: i32,
+}
+
+#[wasm_bindgen]
+impl AnimDecoder {
+    #[wasm_bindgen(constructor)]
+    pub fn new(bytes: Box<[u8]>) -> Result<AnimDecoder, JsError> {
+        let dec = unsafe {
+            let mut options: ffi::WebPAnimDecoderOptions = std::mem::zeroed();
+            if ffi::WebPAnimDecoderOptionsInitInternal(&mut options, DEMUX_ABI) == 0 {
+                return Err(JsError::new("webp decoder options init failed"));
+            }
+            options.color_mode = ffi::WEBP_CSP_MODE::MODE_RGBA;
+            options.use_threads = 0;
+            let data = webp_data(&bytes);
+            ffi::WebPAnimDecoderNewInternal(&data, &options, DEMUX_ABI)
+        };
+        if dec.is_null() {
+            return Err(JsError::new("webp decoder init failed"));
+        }
+        Ok(AnimDecoder {
+            dec,
+            _bytes: bytes,
+            frame: ptr::null_mut(),
+            timestamp: 0,
+        })
+    }
+
+    #[wasm_bindgen(js_name = next)]
+    pub fn next_frame(&mut self) -> Result<bool, JsError> {
+        if unsafe { ffi::WebPAnimDecoderHasMoreFrames(self.dec) } == 0 {
+            return Ok(false);
+        }
+        let mut frame = ptr::null_mut();
+        let mut timestamp = 0;
+        if unsafe { ffi::WebPAnimDecoderGetNext(self.dec, &mut frame, &mut timestamp) } == 0 {
+            return Err(JsError::new("webp frame decode failed"));
+        }
+        self.frame = frame;
+        self.timestamp = timestamp;
+        Ok(true)
+    }
+
+    #[wasm_bindgen(getter)]
+    pub fn frame_ptr(&self) -> u32 {
+        self.frame as usize as u32
+    }
+
+    #[wasm_bindgen(getter)]
+    pub fn end_timestamp(&self) -> i32 {
+        self.timestamp
+    }
+}
+
+impl Drop for AnimDecoder {
+    fn drop(&mut self) {
+        unsafe { ffi::WebPAnimDecoderDelete(self.dec) };
+    }
+}
+
+#[wasm_bindgen]
+pub struct AnimEncoder {
+    enc: *mut ffi::WebPAnimEncoder,
+    width: u32,
+    height: u32,
+    lossless: bool,
+}
+
+#[wasm_bindgen]
+impl AnimEncoder {
+    #[wasm_bindgen(constructor)]
+    pub fn new(
+        width: u32,
+        height: u32,
+        loop_count: u32,
+        lossless: bool,
+    ) -> Result<AnimEncoder, JsError> {
+        let (kmin, kmax) = if lossless { (9, 17) } else { (4, 5) };
+        let enc = unsafe {
+            let mut options: ffi::WebPAnimEncoderOptions = std::mem::zeroed();
+            if ffi::WebPAnimEncoderOptionsInitInternal(&mut options, MUX_ABI) == 0 {
+                return Err(JsError::new("webp encoder options init failed"));
+            }
+            options.anim_params.loop_count = loop_count.min(i32::MAX as u32) as i32;
+            options.anim_params.bgcolor = 0;
+            options.minimize_size = 0;
+            options.allow_mixed = 0;
+            options.kmin = kmin;
+            options.kmax = kmax;
+            ffi::WebPAnimEncoderNewInternal(width as i32, height as i32, &options, MUX_ABI)
+        };
+        if enc.is_null() {
+            return Err(JsError::new("webp encoder init failed"));
+        }
+        Ok(AnimEncoder {
+            enc,
+            width,
+            height,
+            lossless,
+        })
+    }
+
+    pub fn add(
+        &mut self,
+        rgba: &[u8],
+        start_ms: i32,
+        quality: f32,
+        method: i32,
+    ) -> Result<(), JsError> {
+        if rgba.len() as u64 != u64::from(self.width) * u64::from(self.height) * 4 {
+            return Err(JsError::new("webp frame size mismatch"));
+        }
+        let added = unsafe {
+            let mut config: ffi::WebPConfig = std::mem::zeroed();
+            if ffi::WebPConfigInitInternal(
+                &mut config,
+                ffi::WebPPreset::WEBP_PRESET_DEFAULT,
+                quality,
+                ENCODER_ABI,
+            ) == 0
+            {
+                return Err(JsError::new("webp config init failed"));
+            }
+            config.quality = quality;
+            config.method = method;
+            config.lossless = self.lossless as i32;
+            config.thread_level = 0;
+            config.alpha_quality = 100;
+            config.exact = 0;
+            config.use_sharp_yuv = 0;
+            let mut picture: ffi::WebPPicture = std::mem::zeroed();
+            if ffi::WebPPictureInitInternal(&mut picture, ENCODER_ABI) == 0 {
+                return Err(JsError::new("webp picture init failed"));
+            }
+            picture.width = self.width as i32;
+            picture.height = self.height as i32;
+            picture.use_argb = 1;
+            if ffi::WebPPictureImportRGBA(&mut picture, rgba.as_ptr(), self.width as i32 * 4) == 0 {
+                ffi::WebPPictureFree(&mut picture);
+                return Err(JsError::new("webp picture import failed"));
+            }
+            let added = ffi::WebPAnimEncoderAdd(self.enc, &mut picture, start_ms, &config);
+            ffi::WebPPictureFree(&mut picture);
+            added
+        };
+        if added == 0 {
+            return Err(self.error("webp frame encode failed"));
+        }
+        Ok(())
+    }
+
+    pub fn finish(&mut self, end_ms: i32) -> Result<Vec<u8>, JsError> {
+        if unsafe { ffi::WebPAnimEncoderAdd(self.enc, ptr::null_mut(), end_ms, ptr::null()) } == 0 {
+            return Err(self.error("webp encoder flush failed"));
+        }
+        let mut data = ffi::WebPData::default();
+        if unsafe { ffi::WebPAnimEncoderAssemble(self.enc, &mut data) } == 0 {
+            return Err(self.error("webp assemble failed"));
+        }
+        let out = unsafe { std::slice::from_raw_parts(data.bytes, data.size) }.to_vec();
+        unsafe { ffi::WebPFree(data.bytes as *mut _) };
+        Ok(out)
+    }
+
+    fn error(&self, what: &str) -> JsError {
+        let message = unsafe { ffi::WebPAnimEncoderGetError(self.enc) };
+        if message.is_null() {
+            return JsError::new(what);
+        }
+        let detail = unsafe { CStr::from_ptr(message) }.to_string_lossy();
+        JsError::new(&format!("{what}: {detail}"))
+    }
+}
+
+impl Drop for AnimEncoder {
+    fn drop(&mut self) {
+        unsafe { ffi::WebPAnimEncoderDelete(self.enc) };
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn frame(width: u32, height: u32, seed: u8) -> Vec<u8> {
+        (0..width * height)
+            .flat_map(|index| {
+                let value = (index as u8).wrapping_mul(seed);
+                [
+                    value,
+                    seed,
+                    value ^ seed,
+                    if index % 3 == 0 { 0 } else { 255 },
+                ]
+            })
+            .collect()
+    }
+
+    fn encode(lossless: bool) -> Vec<u8> {
+        let mut encoder = AnimEncoder::new(16, 8, 3, lossless).expect("encoder");
+        let delays = [40, 70, 10];
+        let mut start = 0;
+        for (index, delay) in delays.iter().enumerate() {
+            encoder
+                .add(&frame(16, 8, index as u8 + 1), start, 75.0, 4)
+                .expect("add");
+            start += delay;
+        }
+        encoder.finish(start).expect("finish")
+    }
+
+    #[test]
+    fn probe_reports_canvas_frames_loop_alpha_and_lossless() {
+        let lossless = encode(true);
+        assert_eq!(
+            &*webp_probe(&lossless).expect("probe"),
+            &[16, 8, 3, 3, 1, 1]
+        );
+        let lossy = encode(false);
+        let probe = webp_probe(&lossy).expect("probe");
+        assert_eq!(&probe[..5], &[16, 8, 3, 3, 1]);
+        assert_eq!(probe[5], 0);
+    }
+
+    #[test]
+    fn lossless_round_trip_keeps_pixels_and_end_timestamps() {
+        let bytes = encode(true);
+        let mut decoder = AnimDecoder::new(bytes.into_boxed_slice()).expect("decoder");
+        let mut ends = Vec::new();
+        let mut index = 0u8;
+        while decoder.next_frame().expect("next") {
+            let pixels = unsafe { std::slice::from_raw_parts(decoder.frame, 16 * 8 * 4) };
+            let expected = frame(16, 8, index + 1);
+            for (got, want) in pixels.chunks(4).zip(expected.chunks(4)) {
+                assert_eq!(got[3], want[3]);
+                if want[3] != 0 {
+                    assert_eq!(got, want);
+                }
+            }
+            ends.push(decoder.end_timestamp());
+            index += 1;
+        }
+        assert_eq!(ends, [40, 110, 120]);
+    }
+}
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+use std::alloc::{Layout, alloc, alloc_zeroed, dealloc};
+use std::ffi::{c_int, c_void};
+
+const ALIGN: usize = 16;
+
+unsafe fn shim_alloc(size: usize, zeroed: bool) -> *mut c_void {
+    let Some(full) = size.checked_add(ALIGN) else {
+        return std::ptr::null_mut();
+    };
+    let Ok(layout) = Layout::from_size_align(full, ALIGN) else {
+        return std::ptr::null_mut();
+    };
+    unsafe {
+        let ptr = if zeroed {
+            alloc_zeroed(layout)
+        } else {
+            alloc(layout)
+        };
+        if ptr.is_null() {
+            return std::ptr::null_mut();
+        }
+        ptr.cast::<usize>().write(full);
+        ptr.add(ALIGN).cast()
+    }
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn fluxwebp_shim_malloc(size: usize) -> *mut c_void {
+    unsafe { shim_alloc(size, false) }
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn fluxwebp_shim_calloc(nmemb: usize, size: usize) -> *mut c_void {
+    match nmemb.checked_mul(size) {
+        Some(total) => unsafe { shim_alloc(total, true) },
+        None => std::ptr::null_mut(),
+    }
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn fluxwebp_shim_free(ptr: *mut c_void) {
+    if ptr.is_null() {
+        return;
+    }
+    unsafe {
+        let base = ptr.cast::<u8>().sub(ALIGN);
+        let full = base.cast::<usize>().read();
+        dealloc(base, Layout::from_size_align_unchecked(full, ALIGN));
+    }
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn fluxwebp_shim_qsort(
+    base: *mut c_void,
+    n: usize,
+    size: usize,
+    compar: unsafe extern "C" fn(*const c_void, *const c_void) -> c_int,
+) {
+    if n < 2 || size == 0 {
+        return;
+    }
+    unsafe {
+        let bytes = std::slice::from_raw_parts_mut(base.cast::<u8>(), n * size);
+        let copy = bytes.to_vec();
+        let mut idx: Vec<usize> = (0..n).collect();
+        idx.sort_by(|&a, &b| {
+            let r = compar(
+                copy.as_ptr().add(a * size).cast(),
+                copy.as_ptr().add(b * size).cast(),
+            );
+            r.cmp(&0)
+        });
+        for (dst, &src) in idx.iter().enumerate() {
+            bytes[dst * size..dst * size + size]
+                .copy_from_slice(&copy[src * size..src * size + size]);
+        }
+    }
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn fluxwebp_shim_pow(x: f64, y: f64) -> f64 {
+    x.powf(y)
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn fluxwebp_shim_log(x: f64) -> f64 {
+    x.ln()
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn fluxwebp_shim_log10(x: f64) -> f64 {
+    x.log10()
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn fluxwebp_shim_expf(x: f32) -> f32 {
+    x.exp()
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn fluxwebp_shim_logf(x: f32) -> f32 {
+    x.ln()
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn fluxwebp_shim_round(x: f64) -> f64 {
+    x.round()
+}
@@ -11,6 +11,18 @@ const FONT_LICENSE_FILES = [
 	{source: 'LICENSE-IBM-PLEX.txt', asset: 'assets/fonts-LICENSE-IBM-PLEX.txt'},
 ];

+const WASM_LICENSE_FILES = [
+	{source: 'libfluxcore/NOTICE.md', asset: 'assets/libfluxcore-NOTICE.txt'},
+	{source: 'libfluxcore/LICENSE-ZSTD.txt', asset: 'assets/libfluxcore-LICENSE-ZSTD.txt'},
+	{source: 'libfluxcore/LICENSE-ZSTD-SYS.txt', asset: 'assets/libfluxcore-LICENSE-ZSTD-SYS.txt'},
+	{source: 'libfluxcore/LICENSE-ZSTD-RS.txt', asset: 'assets/libfluxcore-LICENSE-ZSTD-RS.txt'},
+	{source: 'libfluxwebp/NOTICE.md', asset: 'assets/libfluxwebp-NOTICE.txt'},
+	{source: 'libfluxwebp/LICENSE-LIBWEBP.txt', asset: 'assets/libfluxwebp-LICENSE-LIBWEBP.txt'},
+	{source: 'libfluxwebp/PATENTS-LIBWEBP.txt', asset: 'assets/libfluxwebp-PATENTS-LIBWEBP.txt'},
+	{source: 'libfluxwebp/LICENSE-LIBWEBP-SYS.txt', asset: 'assets/libfluxwebp-LICENSE-LIBWEBP-SYS.txt'},
+	{source: 'libfluxwebp/simd/LICENSE', asset: 'assets/libfluxwebp-LICENSE-EMSCRIPTEN.txt'},
+];
+
 function resolveStaticCdnEndpoint(staticCdnEndpoint) {
 	const value = staticCdnEndpoint?.trim().replace(/\/+$/, '');
 	return value || STATIC_CDN_ENDPOINT_PLACEHOLDER;
@@ -23,7 +35,8 @@ function generateManifest(staticCdnEndpoint) {
 		short_name: 'Fluxer',
 		description:
 			'Fluxer is a free and open source instant messaging and VoIP platform built for friends, groups, and communities.',
-		start_url: '/',
+		id: '/',
+		start_url: '/app',
 		display: 'standalone',
 		orientation: 'portrait-primary',
 		theme_color: '#4641D9',
@@ -31,6 +44,7 @@ function generateManifest(staticCdnEndpoint) {
 		categories: ['social', 'communication'],
 		lang: 'en',
 		scope: '/',
+		scope_extensions: [],
 		icons: [
 			{
 				src: `${cdn}/web/android-chrome-192x192.png`,
@@ -86,17 +100,18 @@ export class StaticFilesPlugin {
 	constructor(options = {}) {
 		this.staticCdnEndpoint = options.staticCdnEndpoint;
 		this.fontsDir = options.fontsDir;
+		this.wasmCratesDir = options.wasmCratesDir;
 	}

-	emitFontLicenses(compilation) {
-		if (!this.fontsDir) {
+	emitLicenseFiles(compilation, dir, files, subject) {
+		if (!dir) {
 			return;
 		}
-		for (const {source, asset} of FONT_LICENSE_FILES) {
-			const sourcePath = path.join(this.fontsDir, source);
+		for (const {source, asset} of files) {
+			const sourcePath = path.join(dir, source);
 			if (!fs.existsSync(sourcePath)) {
 				throw new Error(
-					`StaticFilesPlugin: ${sourcePath} is missing. The bundled fonts may not be redistributed without it.`,
+					`StaticFilesPlugin: ${sourcePath} is missing. The bundled ${subject} may not be redistributed without it.`,
 				);
 			}
 			compilation.emitAsset(asset, new sources.RawSource(fs.readFileSync(sourcePath)));
@@ -117,7 +132,8 @@ export class StaticFilesPlugin {
 						new sources.RawSource(generateBrowserConfig(this.staticCdnEndpoint)),
 					);
 					compilation.emitAsset('robots.txt', new sources.RawSource(generateRobotsTxt()));
-					this.emitFontLicenses(compilation);
+					this.emitLicenseFiles(compilation, this.fontsDir, FONT_LICENSE_FILES, 'fonts');
+					this.emitLicenseFiles(compilation, this.wasmCratesDir, WASM_LICENSE_FILES, 'WebAssembly modules');
 				},
 			);
 		});
@@ -4,6 +4,7 @@ import {marketingUrl} from '@app/features/messaging/utils/MessagingUrlUtils';

 export const Routes = {
 	HOME: '/',
+	APP: '/app',
 	LOGIN: '/login',
 	REGISTER: '/register',
 	FORGOT_PASSWORD: '/forgot',
@@ -214,7 +214,7 @@ export const RootComponent: React.FC<{children?: React.ReactNode}> = observer(({
 		) {
 			return;
 		}
-		if (location.pathname === Routes.HOME) {
+		if (location.pathname === Routes.HOME || location.pathname === Routes.APP) {
 			return;
 		}
 		hasStartedRestoreRef.current = true;
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: AGPL-3.0-or-later

+import {Routes} from '@app/app/Routes';
 import {RootComponent} from '@app/app/router/components/RootComponent';
 import {NotFoundPage} from '@app/features/app/components/pages/NotFoundPage';
 import {getDefaultLandingPath} from '@app/features/navigation/utils/DefaultLandingUtils';
@@ -22,3 +23,9 @@ export const homeRoute = createRoute({
 	path: '/',
 	onEnter: () => new Redirect(getDefaultLandingPath()),
 });
+export const appRoute = createRoute({
+	getParentRoute: () => rootRoute,
+	id: 'app',
+	path: Routes.APP,
+	onEnter: () => new Redirect(getDefaultLandingPath()),
+});
@@ -7,11 +7,12 @@ import {
 	premiumCallbackRoute,
 } from '@app/app/router/routes/AppRoutes';
 import {authRouteTree} from '@app/app/router/routes/AuthRoutes';
-import {homeRoute, notFoundRoute, rootRoute} from '@app/app/router/routes/RootRoutes';
+import {appRoute, homeRoute, notFoundRoute, rootRoute} from '@app/app/router/routes/RootRoutes';
 import type {RouteConfig} from '@app/features/platform/components/router/RouterTypes';

 const routeTree = rootRoute.addChildren([
 	homeRoute,
+	appRoute,
 	notFoundRoute,
 	premiumCallbackRoute,
 	matureContentCheckCallbackRoute,
@@ -29,7 +29,7 @@ interface ForwardOriginChannel {
 interface BuildForwardDefaultDestinationsRequest {
 	readonly frequentIds: ReadonlyArray<string>;
 	readonly history: ReadonlyArray<string>;
-	readonly isValid: (row: ForwardRowIdentity) => boolean;
+	readonly accepts: (row: ForwardRowIdentity) => boolean;
 	readonly mode: ForwardResultType | null;
 	readonly origin: ForwardDestination | null;
 	readonly pinned: ReadonlyArray<ForwardDestination>;
@@ -51,7 +51,7 @@ export function resolveForwardOrigin(
 export function buildForwardDefaultDestinations({
 	frequentIds,
 	history,
-	isValid,
+	accepts,
 	mode,
 	origin,
 	pinned,
@@ -64,7 +64,7 @@ export function buildForwardDefaultDestinations({
 		...history.slice(0, HISTORY_LIMIT).map((channelId) => resolveChannel(channelId)),
 		...frequentIds.slice(0, FREQUENT_LIMIT).map((channelId) => resolveChannel(channelId)),
 	];
-	const rows = candidates.filter((row): row is ForwardRowIdentity => row != null && isValid(row));
+	const rows = candidates.filter((row): row is ForwardRowIdentity => row != null && accepts(row));
 	const originSelected =
 		origin != null && selected.some((destination) => destination.type === origin.type && destination.id === origin.id);
 	const hiddenIds = origin == null || originSelected ? [] : [origin.id];
@@ -79,10 +79,10 @@ export function buildForwardDefaultDestinations({

 export function filterForwardSearchRows(
 	results: ReadonlyArray<ForwardRowIdentity>,
-	isValid: (row: ForwardRowIdentity) => boolean,
+	accepts: (row: ForwardRowIdentity) => boolean,
 ): ReadonlyArray<ForwardDestinationRow> {
 	return dedupeRows(
-		results.filter((result) => isValid(result)),
+		results.filter((result) => accepts(result)),
 		[],
 	);
 }
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
HampusandGitHub	01f53a168d	feat(push): gate relay delivery on operator consent (#2984 )	2026-09-27 20:33:10 +02:00
HampusandGitHub	336b8b7dcd	fix(forward): make an @silent comment silence the forward too (#2983 )	2026-09-27 20:13:14 +02:00
HampusandGitHub	48d0034239	fix(app-proxy): trust the Play app signing certificate (#2982 )	2026-09-27 19:37:40 +02:00
HampusandGitHub	677ef8491e	fix(desktop): back off failed app loads and offer a retry (#2980 )	2026-09-27 16:18:01 +02:00
HampusandGitHub	6a6119ed1e	fix(push): preview forwarded message content (#2979 )	2026-09-27 13:33:22 +02:00
HampusandGitHub	931327d1dc	fix(push): stop sending notifications for system messages (#2978 )	2026-09-27 13:33:18 +02:00
HampusandGitHub	858a2d9e2b	fix(oauth): stop granting scopes the user turned off (#2968 )	2026-09-26 13:48:23 +02:00
HampusandGitHub	841fb7af41	feat(auth): migrate passkeys to fluxer.com (#2964 )	2026-09-25 22:33:50 +02:00
HampusandGitHub	08e65d41c0	fix(api): clear the perks-sanitized latch when premium returns (#2963 )	2026-09-25 20:13:00 +02:00
HampusandGitHub	f76c4dc041	fix(api): cancel only the subscription the refund belongs to (#2962 )	2026-09-25 20:10:54 +02:00
HampusandGitHub	f1f8ba2031	fix(app): add copy link to link channel context menus (#2959 )	2026-09-25 18:16:20 +02:00
HampusandGitHub	5ab8d745c0	fix(i18n): correct the fluxer.com migration translations (#2958 )	2026-09-25 17:46:07 +02:00
HampusandGitHub	ff62bc89a4	feat(app): add passkey popup bridge for password managers (#2957 )	2026-09-25 17:43:19 +02:00
HampusandGitHub	838bbdb5ec	fix(app): only start the domain migration when the app opens (#2956 )	2026-09-25 16:44:58 +02:00
HampusandGitHub	1c36a59b2c	feat(app): rework quick switcher ranking and show origin icons (#2953 )	2026-09-25 13:59:25 +02:00
HampusandGitHub	6730a242db	feat(web): prepare the fluxer.com domain migration (#2952 )	2026-09-25 13:43:34 +02:00
HampusandGitHub	e62ae77643	refactor(config): trim the default passkey origin list (#2951 )	2026-09-25 13:42:02 +02:00
HampusandGitHub	f4f39e6a89	feat(app): show where forward destinations come from (#2950 )	2026-09-25 13:12:17 +02:00
HampusandGitHub	00bf74cef5	fix(app): handle swapped overwrites when comparing channels (#2949 )	2026-09-24 23:38:04 +02:00
HampusandGitHub	c1c45d835f	fix(app): only parse markdown in rich embeds (#2948 )	2026-09-24 22:50:34 +02:00
HampusandGitHub	bbfe809bef	fix(app): crop animated images on web with libwebp (#2947 )	2026-09-24 22:45:53 +02:00
HampusandGitHub	e0843ac4f5	fix(app): keep guild folder expansion state local (#2944 )	2026-09-24 17:52:33 +02:00
HampusandGitHub	43741cdad8	fix(gateway): always trim the connect snapshot for guild connects (#2943 )	2026-09-24 17:09:48 +02:00
HampusandGitHub	b8e3807262	Revert "fix(push): deliver direct messages without holding them" (#2942 )	2026-09-24 17:09:44 +02:00
HampusandGitHub	3304f01a84	chore(i18n): recompile uk error catalog (#2941 )	2026-09-24 17:09:36 +02:00
fluxer-weblate[bot]andGitHub	2ba463235b	chore(i18n): update translations from Weblate (#2909 )	2026-09-24 16:25:26 +02:00
fluxer-weblate[bot]andGitHub	15136fed59	chore(i18n): update translations from Weblate (#2923 )	2026-09-24 16:25:05 +02:00
HampusandGitHub	6013581dd9	fix(push): deliver direct messages without holding them (#2938 )	2026-09-24 16:21:42 +02:00
HampusandGitHub	7a91f128e9	fix(app-proxy): drop link preview metadata on self-hosted (#2936 )	2026-09-24 16:07:00 +02:00
HampusandGitHub	963ffc5550	feat(push): scope read clears to the enrolled cohort (#2935 )	2026-09-24 15:15:45 +02:00