feat: show the conversation evidence behind each learning trajectory

Reviewers were asked to include or exclude learning trajectories while
only seeing metadata — credit class, confidence, status. The decisions
and their redacted context turns were already captured and stored, but
no endpoint returned them, so the evidence was unreachable from the UI.

Add GET /api/learning/trajectories/:id and an expandable row on the
learning page that fetches on demand.

Also widen SentMessageSchema to accept matrixEventId, imageOutcomeCredit
and imageOutcomeAt. The learning loop added these to SentMessageRecord
and they flow out of /api/messages, but the strict contract rejected
them, breaking the dashboard.

Enable generation with shadow mode off so eligible examples reach reply
prompts.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/reddit-accounts-service.test.ts

@@ -0,0 +1,104 @@
+import Database from 'better-sqlite3';
+import { afterEach, beforeEach, describe, expect, it } from 'vitest';
+import { RedditAccountsRepository } from '../src/database/account-repositories.js';
+import { runMigrations } from '../src/database/client.js';
+import { AccountAuthContext } from '../src/services/account-auth-context.js';
+import { RedditAccountsService } from '../src/services/reddit-accounts.js';
+
+const silentLogger = {
+  info: () => undefined,
+  warn: () => undefined,
+  error: () => undefined,
+  debug: () => undefined,
+} as never;
+
+describe('removing a Reddit account', () => {
+  let db: Database.Database;
+  let accounts: RedditAccountsRepository;
+  let auth: AccountAuthContext;
+  let stopped: string[];
+  let service: RedditAccountsService;
+
+  beforeEach(() => {
+    db = new Database(':memory:');
+    db.pragma('foreign_keys = ON');
+    runMigrations(db);
+    accounts = new RedditAccountsRepository(db);
+    auth = new AccountAuthContext(silentLogger);
+    stopped = [];
+    const runtimes = {
+      get: () => null,
+      stop: async (accountId: string) => { stopped.push(accountId); },
+    };
+    service = new RedditAccountsService(
+      accounts,
+      { import: async () => { throw new Error('not used'); } } as never,
+      auth,
+      runtimes as never,
+    );
+    accounts.upsertVerified({
+      accountId: 't2_alice',
+      redditUsername: 'alice-bot',
+      matrixUserId: '@t2_alice:reddit.com',
+      cookiesJson: JSON.stringify([{ name: 'reddit_session', value: 'secret' }]),
+      matrixCredentialsJson: JSON.stringify({ accessToken: 'matrix-secret' }),
+      now: 100,
+    });
+  });
+
+  afterEach(() => db.close());
+
+  it('stops the runtime before dropping the account and its stored credentials', async () => {
+    const removed = await service.remove('t2_alice');
+
+    expect(stopped).toEqual(['t2_alice']);
+    expect(removed).toMatchObject({
+      accountId: 't2_alice',
+      redditUsername: 'alice-bot',
+      isRunning: false,
+      status: 'login-required',
+    });
+    expect(accounts.get('t2_alice')).toBeNull();
+    expect(service.list()).toEqual([]);
+  });
+
+  it('drops the authenticated session when the removed account held it', async () => {
+    auth.markAuthenticated({
+      accountId: 't2_alice',
+      redditUsername: 'alice-bot',
+      matrixUserId: '@t2_alice:reddit.com',
+    });
+    expect(auth.getSnapshot().accountId).toBe('t2_alice');
+
+    await service.remove('t2_alice');
+
+    expect(auth.getSnapshot()).toMatchObject({ status: 'login-required', accountId: null });
+  });
+
+  it('leaves another account\'s session alone', async () => {
+    accounts.upsertVerified({
+      accountId: 't2_bob',
+      redditUsername: 'bob-bot',
+      matrixUserId: '@t2_bob:reddit.com',
+      cookiesJson: JSON.stringify([{ name: 'reddit_session', value: 'bob-secret' }]),
+      matrixCredentialsJson: JSON.stringify({ accessToken: 'bob-matrix-secret' }),
+      now: 110,
+    });
+    auth.markAuthenticated({
+      accountId: 't2_bob',
+      redditUsername: 'bob-bot',
+      matrixUserId: '@t2_bob:reddit.com',
+    });
+
+    await service.remove('t2_alice');
+
+    expect(auth.getSnapshot()).toMatchObject({ status: 'authenticated', accountId: 't2_bob' });
+    expect(service.list().map((account) => account.accountId)).toEqual(['t2_bob']);
+  });
+
+  it('refuses to remove an account it does not know, without stopping anything', async () => {
+    await expect(service.remove('t2_missing')).rejects.toThrow('Reddit account not found');
+    expect(stopped).toEqual([]);
+    expect(accounts.get('t2_alice')).not.toBeNull();
+  });
+});