Disable unavailable subreddits after Reddit 404

tests/reddit-api.test.ts

@@ -480,14 +480,29 @@ describe('RedditApiClient', () => {
   });
 
   describe('getNewPosts', () => {
-    it('returns empty array for 404 subreddit', async () => {
+    it('throws a permanent-disable signal for a plain 404 subreddit', async () => {
       const error = { isAxiosError: true, response: { status: 404 } };
       const mockAxios = { get: vi.fn().mockRejectedValue(error) };
       vi.mocked(axios.create).mockReturnValue(mockAxios as any);
 
       const client2 = new RedditApiClient(getTestConfig(), logger);
-      const result = await client2.getNewPosts('nonexistent');
-      expect(result).toEqual([]);
+      await expect(client2.getNewPosts('nonexistent')).rejects.toMatchObject({
+        name: 'RedditSubredditUnavailableError', subreddit: 'nonexistent',
+      });
+    });
+
+    it('throws the same permanent-disable signal for Reddit banned responses', async () => {
+      const error = {
+        isAxiosError: true,
+        response: { status: 404, data: { reason: 'banned', message: 'Not Found', error: 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.getNewPosts('banned-sub')).rejects.toMatchObject({
+        name: 'RedditSubredditUnavailableError', subreddit: 'banned-sub',
+      });
     });
 
     it('returns empty array and explains an initial 403 access denial', async () => {