feat: persist settings and enrich conversation context

tests/reddit-api.test.ts

@@ -1,5 +1,7 @@
 import { describe, it, expect, vi, beforeEach } from 'vitest';
 import axios from 'axios';
+import type { AxiosInstance } from 'axios';
+import type { BrowserContext } from 'playwright';
 import { RedditApiClient } from '../src/reddit/api.js';
 import type { RedditPost } from '../src/reddit/api.js';
 import { createMockLogger } from '../tests/mockLogger.js';
@@ -394,6 +396,44 @@ describe('RedditApiClient', () => {
     });
   });
 
+  describe('resolveUsernameToT2', () => {
+    it('uses the imported Reddit session and normalizes the account ID', async () => {
+      const mockAxios = {
+        get: vi.fn().mockResolvedValue({ data: { data: { id: 'abc123' } } }),
+      };
+      vi.mocked(axios.create).mockReturnValue(mockAxios as unknown as AxiosInstance);
+      const client2 = new RedditApiClient(getTestConfig(), logger);
+      const cookies = vi.fn().mockResolvedValue([
+        { name: 'reddit_session', value: 'session-value' },
+      ]);
+      client2.setBrowserContext({ cookies } as unknown as BrowserContext);
+
+      await expect(client2.resolveUsernameToT2('alice')).resolves.toBe('t2_abc123');
+      expect(mockAxios.get).toHaveBeenCalledWith('/user/alice/about.json', {
+        params: { raw_json: 1 },
+        headers: { Cookie: 'reddit_session=session-value' },
+      });
+    });
+
+    it('returns null only when Reddit confirms the user is missing', async () => {
+      const error = { isAxiosError: true, response: { status: 404 } };
+      const mockAxios = { get: vi.fn().mockRejectedValue(error) };
+      vi.mocked(axios.create).mockReturnValue(mockAxios as unknown as AxiosInstance);
+      const client2 = new RedditApiClient(getTestConfig(), logger);
+
+      await expect(client2.resolveUsernameToT2('missing')).resolves.toBeNull();
+    });
+
+    it('does not misclassify a 403 as an unknown user', async () => {
+      const error = { isAxiosError: true, response: { status: 403 } };
+      const mockAxios = { get: vi.fn().mockRejectedValue(error) };
+      vi.mocked(axios.create).mockReturnValue(mockAxios as unknown as AxiosInstance);
+      const client2 = new RedditApiClient(getTestConfig(), logger);
+
+      await expect(client2.resolveUsernameToT2('alice')).rejects.toBe(error);
+    });
+  });
+
   describe('getNewPosts', () => {
     it('returns empty array for 404 subreddit', async () => {
       const error = { isAxiosError: true, response: { status: 404 } };