diff --git a/fluxer_api/src/api/channel/services/StreamService.ts b/fluxer_api/src/api/channel/services/StreamService.ts
index 0f7114140..61bd4360a 100644
--- a/fluxer_api/src/api/channel/services/StreamService.ts
+++ b/fluxer_api/src/api/channel/services/StreamService.ts
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: AGPL-3.0-or-later
 
-import {Permissions} from '@fluxer/constants/src/ChannelConstants';
+import {ChannelTypes, Permissions} from '@fluxer/constants/src/ChannelConstants';
+import {InvalidChannelTypeError} from '@fluxer/errors/src/domains/channel/InvalidChannelTypeError';
 import {InvalidStreamKeyFormatError} from '@fluxer/errors/src/domains/channel/InvalidStreamKeyFormatError';
 import {InvalidStreamThumbnailPayloadError} from '@fluxer/errors/src/domains/channel/InvalidStreamThumbnailPayloadError';
 import {StreamKeyChannelMismatchError} from '@fluxer/errors/src/domains/channel/StreamKeyChannelMismatchError';
@@ -90,6 +91,9 @@ export class StreamService {
 			if (params.parsedKey.guildId !== channel.guildId.toString()) {
 				throw new StreamKeyScopeMismatchError();
 			}
+			if (channel.type !== ChannelTypes.GUILD_VOICE) {
+				throw new InvalidChannelTypeError();
+			}
 			const hasConnect = await this.gatewayService.checkPermission({
 				guildId: channel.guildId,
 				channelId: params.channelId,
@@ -99,8 +103,13 @@ export class StreamService {
 			if (!hasConnect) {
 				throw new MissingPermissionsError();
 			}
-		} else if (params.parsedKey.scope !== 'dm') {
-			throw new StreamKeyScopeMismatchError();
+		} else {
+			if (params.parsedKey.scope !== 'dm') {
+				throw new StreamKeyScopeMismatchError();
+			}
+			if (channel.type !== ChannelTypes.DM && channel.type !== ChannelTypes.GROUP_DM) {
+				throw new InvalidChannelTypeError();
+			}
 		}
 		if (params.parsedKey.channelId !== params.channelId.toString()) {
 			throw new StreamKeyChannelMismatchError();
@@ -166,10 +175,7 @@ export class StreamService {
 			channelId,
 			parsedKey,
 		});
-		const preview = await this.streamPreviewService.getPreview(params.streamKey);
-		if (preview) {
-		}
-		return preview;
+		return this.streamPreviewService.getPreview(params.streamKey);
 	}
 
 	async uploadPreview(params: {
diff --git a/fluxer_api/src/api/channel/tests/StreamChannelType.test.ts b/fluxer_api/src/api/channel/tests/StreamChannelType.test.ts
new file mode 100644
index 000000000..be77809c8
--- /dev/null
+++ b/fluxer_api/src/api/channel/tests/StreamChannelType.test.ts
@@ -0,0 +1,86 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import {APIErrorCodes} from '@fluxer/constants/src/ApiErrorCodes';
+import {ChannelTypes} from '@fluxer/constants/src/ChannelConstants';
+import {afterAll, beforeAll, beforeEach, describe, it} from 'vitest';
+import {createTestAccount} from '../../auth/tests/AuthTestUtils';
+import {type ApiTestHarness, createApiTestHarness} from '../../test/ApiTestHarness';
+import {HTTP_STATUS} from '../../test/TestConstants';
+import {createBuilder} from '../../test/TestRequestBuilder';
+import {createChannel, createDmChannel, createFriendship, createGuild, getChannel} from './ChannelTestUtils';
+
+const CONNECTION_ID = 'conn-channel-type';
+
+describe('stream key channel type gate', () => {
+	let harness: ApiTestHarness;
+
+	beforeAll(async () => {
+		harness = await createApiTestHarness();
+	});
+
+	beforeEach(async () => {
+		await harness.reset();
+	});
+
+	afterAll(async () => {
+		await harness?.shutdown();
+	});
+
+	async function createGuildChannels(): Promise<{
+		token: string;
+		textKey: string;
+		voiceKey: string;
+	}> {
+		const owner = await createTestAccount(harness);
+		const guild = await createGuild(harness, owner.token, 'Stream Type Guild');
+		const textChannel = await getChannel(harness, owner.token, guild.system_channel_id!);
+		const voiceChannel = await createChannel(harness, owner.token, guild.id, 'stream-voice', ChannelTypes.GUILD_VOICE);
+		return {
+			token: owner.token,
+			textKey: `${guild.id}:${textChannel.id}:${CONNECTION_ID}`,
+			voiceKey: `${guild.id}:${voiceChannel.id}:${CONNECTION_ID}`,
+		};
+	}
+
+	it('rejects a region update whose key names a guild text channel', async () => {
+		const {token, textKey} = await createGuildChannels();
+		await createBuilder(harness, token)
+			.patch(`/streams/${textKey}/stream`)
+			.body({region: 'us-east'})
+			.expect(HTTP_STATUS.BAD_REQUEST, APIErrorCodes.INVALID_CHANNEL_TYPE)
+			.execute();
+	});
+
+	it('rejects a preview read whose key names a guild text channel', async () => {
+		const {token, textKey} = await createGuildChannels();
+		await createBuilder(harness, token)
+			.get(`/streams/${textKey}/preview`)
+			.expect(HTTP_STATUS.BAD_REQUEST, APIErrorCodes.INVALID_CHANNEL_TYPE)
+			.execute();
+	});
+
+	it('lets a guild voice key past the type gate and fail on the missing voice state', async () => {
+		const {token, voiceKey} = await createGuildChannels();
+		await createBuilder(harness, token)
+			.patch(`/streams/${voiceKey}/stream`)
+			.body({region: 'us-east'})
+			.expect(HTTP_STATUS.FORBIDDEN, APIErrorCodes.ACCESS_DENIED)
+			.execute();
+	});
+
+	it('lets a guild voice key past the type gate and read an absent preview', async () => {
+		const {token, voiceKey} = await createGuildChannels();
+		await createBuilder(harness, token).get(`/streams/${voiceKey}/preview`).expect(HTTP_STATUS.NOT_FOUND).execute();
+	});
+
+	it('lets a dm key past the type gate and read an absent preview', async () => {
+		const owner = await createTestAccount(harness);
+		const recipient = await createTestAccount(harness);
+		await createFriendship(harness, owner, recipient);
+		const dm = await createDmChannel(harness, owner.token, recipient.userId);
+		await createBuilder(harness, owner.token)
+			.get(`/streams/dm:${dm.id}:${CONNECTION_ID}/preview`)
+			.expect(HTTP_STATUS.NOT_FOUND)
+			.execute();
+	});
+});
diff --git a/fluxer_api/src/api/channel/tests/StreamPreviewOversized.test.ts b/fluxer_api/src/api/channel/tests/StreamPreviewOversized.test.ts
new file mode 100644
index 000000000..4f38a9a0e
--- /dev/null
+++ b/fluxer_api/src/api/channel/tests/StreamPreviewOversized.test.ts
@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+
+import {STREAM_PREVIEW_CONTENT_TYPE_JPEG, STREAM_PREVIEW_MAX_BYTES} from '@fluxer/constants/src/StreamConstants';
+import {afterAll, beforeAll, beforeEach, describe, expect, it} from 'vitest';
+import {createTestAccount} from '../../auth/tests/AuthTestUtils';
+import {Config} from '../../Config';
+import {getCacheService} from '../../middleware/ServiceSingletons';
+import {type ApiTestHarness, createApiTestHarness} from '../../test/ApiTestHarness';
+import {createDmChannel, createFriendship} from './ChannelTestUtils';
+
+const CONNECTION_ID = 'conn-oversized';
+
+describe('stream preview object size ceiling', () => {
+	let harness: ApiTestHarness;
+
+	beforeAll(async () => {
+		harness = await createApiTestHarness();
+	});
+
+	beforeEach(async () => {
+		await harness.reset();
+		harness.storageService.reset();
+	});
+
+	afterAll(async () => {
+		await harness?.shutdown();
+	});
+
+	async function createStoredPreview(fileData: Uint8Array): Promise<{token: string; streamKey: string}> {
+		const owner = await createTestAccount(harness);
+		const viewer = await createTestAccount(harness);
+		await createFriendship(harness, owner, viewer);
+		const dm = await createDmChannel(harness, owner.token, viewer.userId);
+		const streamKey = `dm:${dm.id}:${CONNECTION_ID}`;
+		await getCacheService().set(
+			`stream_preview:${streamKey}`,
+			{
+				bucket: Config.s3.buckets.uploads,
+				key: `stream_previews/${dm.id}-${CONNECTION_ID}.jpg`,
+				updatedAt: Date.now(),
+				ownerId: owner.userId,
+				channelId: dm.id,
+				contentType: STREAM_PREVIEW_CONTENT_TYPE_JPEG,
+			},
+			60,
+		);
+		harness.storageService.configure({fileData});
+		return {token: owner.token, streamKey};
+	}
+
+	it('answers an empty 404 when the stored object is larger than the preview ceiling', async () => {
+		const {token, streamKey} = await createStoredPreview(new Uint8Array(STREAM_PREVIEW_MAX_BYTES + 1));
+		const response = await harness.requestJson({
+			path: `/v1/streams/${streamKey}/preview`,
+			headers: {authorization: token},
+		});
+		expect(response.status).toBe(404);
+		expect(await response.text()).toBe('');
+		expect(harness.storageService.readObjectSpy).toHaveBeenCalledWith(
+			Config.s3.buckets.uploads,
+			expect.any(String),
+			STREAM_PREVIEW_MAX_BYTES,
+		);
+	});
+
+	it('serves a stored object that fits inside the preview ceiling', async () => {
+		const {token, streamKey} = await createStoredPreview(new Uint8Array([0xff, 0xd8, 0x00, 0xff, 0xd9]));
+		const response = await harness.requestJson({
+			path: `/v1/streams/${streamKey}/preview`,
+			headers: {authorization: token},
+		});
+		expect(response.status).toBe(200);
+		expect(response.headers.get('content-type')).toBe(STREAM_PREVIEW_CONTENT_TYPE_JPEG);
+		expect(new Uint8Array(await response.arrayBuffer())).toEqual(new Uint8Array([0xff, 0xd8, 0x00, 0xff, 0xd9]));
+	});
+});
diff --git a/fluxer_api/src/api/infrastructure/StorageService.test.ts b/fluxer_api/src/api/infrastructure/StorageService.test.ts
index 297ee9a19..1c804ae62 100644
--- a/fluxer_api/src/api/infrastructure/StorageService.test.ts
+++ b/fluxer_api/src/api/infrastructure/StorageService.test.ts
@@ -71,9 +71,12 @@ class TestStorageService extends StorageService {
 		this.readObjects.push(
 			maxBytes === undefined ? {bucket: _bucket, key: _key} : {bucket: _bucket, key: _key, maxBytes},
 		);
-		return maxBytes !== undefined && this.sourceData.length > maxBytes
-			? this.sourceData.slice(0, maxBytes)
-			: this.sourceData;
+		if (maxBytes !== undefined && this.sourceData.length > maxBytes) {
+			throw new Error(
+				`Stream exceeds maximum buffer size of ${maxBytes} bytes (got at least ${this.sourceData.length} bytes)`,
+			);
+		}
+		return this.sourceData;
 	}
 
 	override async copyObject(params: CopyObjectTestParams): Promise<void> {
@@ -188,6 +191,40 @@ describe('StorageService.copyObjectWithMetadataStripping', () => {
 	});
 });
 
+interface S3ClientProbe {
+	client: {send: (command: unknown) => Promise<{Body: Readable}>};
+}
+
+function stubObjectBody(service: StorageService, chunks: Array<Uint8Array>): void {
+	(service as unknown as S3ClientProbe).client = {
+		send: async () => ({Body: Readable.from(chunks.map((chunk) => Buffer.from(chunk)))}),
+	};
+}
+
+describe('StorageService.readObject', () => {
+	it('returns the whole object when it fits inside the ceiling', async () => {
+		const service = new StorageService();
+		stubObjectBody(service, [new Uint8Array([1, 2, 3]), new Uint8Array([4, 5])]);
+		const data = await service.readObject('fluxer-uploads', 'stream_previews/preview.jpg', 5);
+		expect(data).toEqual(new Uint8Array([1, 2, 3, 4, 5]));
+	});
+
+	it('rejects an object larger than the ceiling instead of truncating it', async () => {
+		const service = new StorageService();
+		stubObjectBody(service, [new Uint8Array([1, 2, 3]), new Uint8Array([4, 5, 6])]);
+		await expect(service.readObject('fluxer-uploads', 'stream_previews/preview.jpg', 5)).rejects.toThrow(
+			/^Stream exceeds maximum buffer size of 5 bytes/,
+		);
+	});
+
+	it('reads the whole object when no ceiling is given', async () => {
+		const service = new StorageService();
+		stubObjectBody(service, [new Uint8Array([1, 2, 3]), new Uint8Array([4, 5, 6])]);
+		const data = await service.readObject('fluxer-uploads', 'stream_previews/preview.jpg');
+		expect(data).toEqual(new Uint8Array([1, 2, 3, 4, 5, 6]));
+	});
+});
+
 describe('provider selection', () => {
 	interface ClientProbe {
 		client: {config: {region: () => Promise<string>; endpoint?: () => Promise<{hostname: string}>}};