Improve Reddit chat and media reliability

tests/web/media-route.test.ts

@@ -1,6 +1,7 @@
 import express from 'express';
 import type { AddressInfo } from 'node:net';
 import { afterEach, describe, expect, it, vi } from 'vitest';
+import { MediaResponseSchema } from '../../packages/api-contracts/src/media.js';
 import type { WebContext } from '../../src/web/context.js';
 import { createMediaRouter } from '../../src/web/routes/media.js';
 
@@ -63,4 +64,35 @@ describe('media route username presentation', () => {
     expect(JSON.stringify(body)).not.toContain('t2_missing');
     expect(body[0]).toMatchObject({ chatUsername: null, sender: 'Unknown Reddit user' });
   });
+
+  it('keeps the internal account ID out of the public media item', async () => {
+    const context = {
+      logger: { error: vi.fn() },
+      services: {
+        media: { getMediaItems: vi.fn().mockResolvedValue([{
+          accountId: 't2_owner', id: 'one', chatUsername: 'alice', chatRoomId: 'room-one', sender: 'alice',
+          timestamp: 1, originalUrl: 'mxc://one', fileName: 'one.jpg', relativePath: 'one.jpg', createdAt: 2,
+        }]) },
+        chat: {
+          getCachedConversations: vi.fn().mockResolvedValue([]),
+          resolveSenderDisplay: vi.fn((identity: string) => identity),
+        },
+        redditAccounts: {
+          get: vi.fn().mockReturnValue({ accountId: 't2_owner', redditUsername: 'owner' }),
+        },
+      },
+    } as unknown as WebContext;
+    const app = express().use('/api', createMediaRouter(context));
+
+    const response = await request(app, '/api/media');
+    const body: unknown = await response.json();
+
+    expect(MediaResponseSchema.parse(body)).toEqual([
+      expect.objectContaining({
+        id: 'one',
+        owner: { accountId: 't2_owner', redditUsername: 'owner' },
+      }),
+    ]);
+    expect(body).not.toEqual([expect.objectContaining({ accountId: expect.anything() })]);
+  });
 });