feat(MAT-174): LLM-based result filtering for cron search jobs

Brave Search results are passed through LiteLLM (claude-haiku) when
job config includes a `criteria` field. LLM returns indices of matching
results, filtering out noise before posting to Matrix.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/test_cron_brave_search.py

@@ -148,3 +148,120 @@ class TestBraveSearchExecutor:
                 bs.BRAVE_API_KEY = original_key
 
         assert result["status"] == "no_results"
+
+    @pytest.mark.asyncio
+    async def test_llm_filter_keeps_matching_results(self):
+        """LLM filter should only keep results that match criteria."""
+        import cron.brave_search as bs
+        orig_key, orig_url, orig_llm_key = bs.BRAVE_API_KEY, bs.LITELLM_URL, bs.LITELLM_KEY
+        bs.BRAVE_API_KEY = "test-key"
+        bs.LITELLM_URL = "http://llm:4000/v1"
+        bs.LITELLM_KEY = "sk-test"
+
+        job = {
+            "id": "j1",
+            "name": "BMW Search",
+            "jobType": "brave_search",
+            "config": {"query": "BMW X3 damaged", "maxResults": 5, "criteria": "Must be BMW X3, petrol, <=2019, damaged"},
+            "targetRoom": "!room:cars",
+            "dedupKeys": [],
+        }
+
+        brave_resp = MagicMock()
+        brave_resp.json.return_value = {"web": {"results": [
+            {"title": "BMW X3 2018 Unfallwagen Benzin", "url": "https://a.com", "description": "Damaged"},
+            {"title": "Toyota Corolla 2020", "url": "https://b.com", "description": "Not a BMW"},
+            {"title": "BMW X3 2017 Diesel crash", "url": "https://c.com", "description": "Diesel"},
+        ]}}
+        brave_resp.raise_for_status = MagicMock()
+
+        llm_resp = MagicMock()
+        llm_resp.json.return_value = {"choices": [{"message": {"content": "[0]"}}]}
+        llm_resp.raise_for_status = MagicMock()
+
+        send_text = AsyncMock()
+
+        with patch("httpx.AsyncClient") as mock_cls:
+            mock_client = AsyncMock()
+            mock_cls.return_value.__aenter__ = AsyncMock(return_value=mock_client)
+            mock_cls.return_value.__aexit__ = AsyncMock(return_value=False)
+            mock_client.get = AsyncMock(return_value=brave_resp)
+            mock_client.post = AsyncMock(return_value=llm_resp)
+
+            try:
+                result = await execute_brave_search(job=job, send_text=send_text)
+            finally:
+                bs.BRAVE_API_KEY, bs.LITELLM_URL, bs.LITELLM_KEY = orig_key, orig_url, orig_llm_key
+
+        assert result["status"] == "success"
+        assert result["newDedupKeys"] == ["https://a.com"]
+        msg = send_text.call_args[0][1]
+        assert "Unfallwagen" in msg
+        assert "Toyota" not in msg
+
+    @pytest.mark.asyncio
+    async def test_llm_filter_no_matches_returns_no_results(self):
+        """When LLM filter rejects all results, status should be no_results."""
+        import cron.brave_search as bs
+        orig_key, orig_url, orig_llm_key = bs.BRAVE_API_KEY, bs.LITELLM_URL, bs.LITELLM_KEY
+        bs.BRAVE_API_KEY = "test-key"
+        bs.LITELLM_URL = "http://llm:4000/v1"
+        bs.LITELLM_KEY = "sk-test"
+
+        job = {
+            "id": "j1", "name": "Search", "jobType": "brave_search",
+            "config": {"query": "test", "criteria": "Must be exactly X"},
+            "targetRoom": "!room:test", "dedupKeys": [],
+        }
+
+        brave_resp = MagicMock()
+        brave_resp.json.return_value = {"web": {"results": [{"title": "Nope", "url": "https://x.com", "description": "No"}]}}
+        brave_resp.raise_for_status = MagicMock()
+
+        llm_resp = MagicMock()
+        llm_resp.json.return_value = {"choices": [{"message": {"content": "[]"}}]}
+        llm_resp.raise_for_status = MagicMock()
+
+        send_text = AsyncMock()
+
+        with patch("httpx.AsyncClient") as mock_cls:
+            mock_client = AsyncMock()
+            mock_cls.return_value.__aenter__ = AsyncMock(return_value=mock_client)
+            mock_cls.return_value.__aexit__ = AsyncMock(return_value=False)
+            mock_client.get = AsyncMock(return_value=brave_resp)
+            mock_client.post = AsyncMock(return_value=llm_resp)
+
+            try:
+                result = await execute_brave_search(job=job, send_text=send_text)
+            finally:
+                bs.BRAVE_API_KEY, bs.LITELLM_URL, bs.LITELLM_KEY = orig_key, orig_url, orig_llm_key
+
+        assert result["status"] == "no_results"
+        send_text.assert_not_called()
+
+    @pytest.mark.asyncio
+    async def test_no_criteria_skips_llm_filter(self, job):
+        """Without criteria, results pass through without LLM call."""
+        import cron.brave_search as bs
+        orig_key = bs.BRAVE_API_KEY
+        bs.BRAVE_API_KEY = "test-key"
+
+        mock_response = MagicMock()
+        mock_response.json.return_value = {"web": {"results": [{"title": "R", "url": "https://new.com", "description": "D"}]}}
+        mock_response.raise_for_status = MagicMock()
+
+        send_text = AsyncMock()
+
+        with patch("httpx.AsyncClient") as mock_cls:
+            mock_client = AsyncMock()
+            mock_cls.return_value.__aenter__ = AsyncMock(return_value=mock_client)
+            mock_cls.return_value.__aexit__ = AsyncMock(return_value=False)
+            mock_client.get = AsyncMock(return_value=mock_response)
+
+            try:
+                result = await execute_brave_search(job=job, send_text=send_text)
+            finally:
+                bs.BRAVE_API_KEY = orig_key
+
+        assert result["status"] == "success"
+        mock_client.post.assert_not_called()