feat: add agent API and operational analytics

tests/chat-service-progressive-backfill.test.ts

@@ -85,13 +85,9 @@ describe('ChatService progressive full backfill', () => {
       expect(repos.messagesRepo.getResponseRateTrend()).toEqual([
         expect.objectContaining({ totalSent: 1, totalResponses: 1, responseRate: 100 }),
       ]);
-      expect(repos.successfulMessagesRepo.getRecent()).toEqual([
-        expect.objectContaining({
-          originalMessage: 'Hello Alice',
-          postTitle: 'Source post',
-          subreddit: 'example',
-        }),
-      ]);
+      // A single reply counts toward response performance, but the
+      // reciprocal-engagement policy excludes it from learning examples.
+      expect(repos.successfulMessagesRepo.getRecent()).toEqual([]);
     } finally {
       db.close();
       await fs.rm(tmpDir, { recursive: true, force: true });