fix(app): gate one-Tab message focus behind an experiment (#2762)

fluxer_admin/src/templates/pages/instance_config.rs

@@ -5,9 +5,10 @@ use crate::{
         AppPublicConfigResponse, ExperimentDeliveryConfigResponse, GatewayRolloutConfigResponse,
         InstanceConfigResponse, InstanceIntegrationsResponse, InstanceMediaResponse,
         InstancePolicyResponse, InstanceRegistrationResponse, LimitConfigResponse,
-        MessageHoverTrackingConfigResponse, NoiseSuppressionBackend, PendingRegistrationResponse,
-        RegistrationUrlResponse, SsoConfigResponse, VOICE_NS_MAX_GUILD_OVERRIDES,
-        VOICE_NS_MAX_TARGETED_USERS, VoiceNoiseSuppressionConfigResponse,
+        MessageHoverTrackingConfigResponse, MessageKeyboardFocusConfigResponse,
+        NoiseSuppressionBackend, PendingRegistrationResponse, RegistrationUrlResponse,
+        SsoConfigResponse, VOICE_NS_MAX_GUILD_OVERRIDES, VOICE_NS_MAX_TARGETED_USERS,
+        VoiceNoiseSuppressionConfigResponse,
     },
     config::AdminConfig,
     middleware::auth::AuthContext,
@@ -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))
                         (message_hover_tracking_section(base, csrf_token, &instance_config.message_hover_tracking))
+                        (message_keyboard_focus_section(base, csrf_token, &instance_config.message_keyboard_focus))
                         (experiment_delivery_section(base, csrf_token, &instance_config.experiment_delivery))
                         @if let Some(limit_config) = limit_config {
                             (limit_config_section(base, limit_config))
@@ -1280,6 +1282,110 @@ fn message_hover_tracking_section(
     )
 }
 
+fn message_keyboard_focus_section(
+    base: &str,
+    csrf_token: &str,
+    message_keyboard_focus: &MessageKeyboardFocusConfigResponse,
+) -> Markup {
+    let status = if message_keyboard_focus.enabled {
+        ("Live", BadgeVariant::Success)
+    } else {
+        ("Inert", BadgeVariant::Default)
+    };
+    let included_user_ids = message_keyboard_focus.included_user_ids.join("\n");
+    let excluded_user_ids = message_keyboard_focus.excluded_user_ids.join("\n");
+    section_card_with_description(
+        "Message Keyboard Focus",
+        "Picks whether targeted clients run the keyboard navigation rework in the message list. \
+         A targeted client reaches the message list from the composer with one Tab, walks \
+         messages with the arrow keys through revealed blocked groups, and draws the focus ring \
+         inside each row. While the master switch below is off every client keeps the keyboard \
+         navigation it ships with, whatever the rest of these fields say.",
+        html! {
+            form method="post" action={(base) "/instance-config?action=update_message_keyboard_focus"} {
+                (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 " (message_keyboard_focus.config_version)
+                        }
+                    }
+                    (checkbox(
+                        "message_keyboard_focus_enabled",
+                        "true",
+                        "Serve message keyboard focus assignments to clients",
+                        message_keyboard_focus.enabled,
+                        true,
+                    ))
+                    p class="text-xs text-neutral-500" {
+                        "Off is the safe state. With this unchecked every client is told the \
+                         rollout is inert and keeps its current keyboard navigation, so the rollout \
+                         and targeting fields below have no effect at all."
+                    }
+
+                    h3 class="text-sm font-semibold text-neutral-900" { "Rollout" }
+                    (number_field(
+                        "message_keyboard_focus_rollout_basis_points",
+                        "Rollout (basis points)",
+                        &message_keyboard_focus.rollout_basis_points.to_string(),
+                        Some(0), Some(10000), "1",
+                        Some("Share of users bucketed into the canary, in basis points: 0 is nobody, 100 is 1%, 10000 is everybody."),
+                    ))
+                    div class="flex flex-col gap-2" {
+                        (text_input(
+                            "message_keyboard_focus_rollout_salt",
+                            "Rollout Salt",
+                            &message_keyboard_focus.rollout_salt,
+                            "message-keyboard-focus-v1",
+                        ))
+                        p class="text-xs text-neutral-500" {
+                            "Seeds the bucketing hash. Changing it reshuffles which users fall \
+                             inside the percentage above. Leave it alone to keep the current \
+                             cohort stable."
+                        }
+                    }
+                    div class="flex flex-col gap-2" {
+                        (textarea_input(
+                            "message_keyboard_focus_included_user_ids",
+                            "Always-on User IDs",
+                            "1500000000000000001\n1500000000000000002",
+                            &included_user_ids,
+                            4,
+                            false,
+                        ))
+                        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(
+                            "message_keyboard_focus_excluded_user_ids",
+                            "Never-on User IDs",
+                            "1500000000000000003\n1500000000000000004",
+                            &excluded_user_ids,
+                            4,
+                            false,
+                        ))
+                        p class="text-xs text-neutral-500" {
+                            "Same format. Exclusion wins over both the always-on list and the \
+                             percentage, so this is the per-user kill switch."
+                        }
+                    }
+
+                    (form_actions(html! {
+                        (submit_button("Save Message Keyboard Focus Configuration"))
+                    }))
+                }
+            }
+        },
+    )
+}
+
 fn experiment_delivery_section(
     base: &str,
     csrf_token: &str,