style: integrate CodeRabbit review feedback

- Add

@pytest
.mark.unit to streaming fix tests
- Simplify API key fallback: nested ternary → (x or y) or None
- Clean up commented-out event handler code in app.py
- Add language specifiers to markdown code blocks (text, bash)
- Remove redundant fallback in judges.py _extract_key_findings

All 138 tests passing.

docs/bugs/P1_MAGENTIC_STREAMING_AND_KEY_PERSISTENCE.md

@@ -14,7 +14,7 @@
 
 ### Symptoms
 When running Magentic (Advanced) mode, the UI shows hundreds of individual lines like:
-```
+```text
 📡 STREAMING: Below
 📡 STREAMING: is
 📡 STREAMING: a
@@ -157,7 +157,7 @@ Gradio's `ChatInterface` with `additional_inputs` has known issues:
 - Replaced all `OpenAIModel` imports with `OpenAIChatModel` in `src/app.py` and `src/utils/llm_factory.py`.
 
 ### Test Results
-```
+```bash
 uv run pytest tests/ -q
 ============================= 138 passed in 20.60s =============================
 ```

src/agent_factory/judges.py

@@ -451,12 +451,12 @@ class MockJudgeHandler:
 
     def _extract_key_findings(self, evidence: list[Evidence], max_findings: int = 5) -> list[str]:
         """Extract key findings from evidence titles."""
-        findings = _extract_titles_from_evidence(
+        # Helper guarantees non-empty list when fallback_message is provided
+        return _extract_titles_from_evidence(
             evidence,
             max_items=max_findings,
             fallback_message="No specific findings extracted (demo mode)",
         )
-        return findings if findings else ["No specific findings extracted (demo mode)"]
 
     def _extract_drug_candidates(self, question: str, evidence: list[Evidence]) -> list[str]:
         """Extract drug candidates - demo mode returns honest message."""

src/app.py

@@ -127,10 +127,8 @@ async def research_agent(
         yield "Please enter a research question."
         return
 
-    # BUG FIX: Use state for persistence, fallback to textbox
-    # If user just entered a key (api_key is not empty), use it and update state
-    # Otherwise, use the persisted state value
-    user_api_key = api_key.strip() if api_key else api_key_state.strip() if api_key_state else None
+    # BUG FIX: Prefer freshly-entered key, then persisted state
+    user_api_key = (api_key.strip() or api_key_state.strip()) or None
 
     # Check available keys
     has_openai = bool(os.getenv("OPENAI_API_KEY"))
@@ -267,14 +265,8 @@ def create_demo() -> tuple[gr.ChatInterface, gr.Accordion]:
         ],
     )
 
-    # Wire up API key change to update state
-    # This ensures that when user types, state is updated.
-    # When examples are clicked (and only modify first 2 args), state remains.
-    # Note: This requires a Blocks context, which ChatInterface doesn't expose easily here.
-    # However, by removing the empty strings from the examples list above,
-    # we prevent the API key from being overwritten in the first place,
-    # so the api_key textbox retains its value, and research_agent receives it directly.
-    # api_key_input.change(lambda x: x, inputs=api_key_input, outputs=api_key_state)
+    # API key persists because examples only include [message, mode] columns,
+    # so Gradio doesn't overwrite the api_key textbox when examples are clicked.
 
     return demo, additional_inputs_accordion
 

tests/unit/test_streaming_fix.py

@@ -7,6 +7,7 @@ import pytest
 from src.utils.models import AgentEvent
 
 
+@pytest.mark.unit
 @pytest.mark.asyncio
 async def test_streaming_events_are_buffered_not_spammed():
     """
@@ -92,6 +93,7 @@ async def test_streaming_events_are_buffered_not_spammed():
         app_module.configure_orchestrator = original_configure
 
 
+@pytest.mark.unit
 @pytest.mark.asyncio
 async def test_api_key_state_parameter_exists():
     """