fix: address CodeRabbit review feedback

- Fix research_agent param types: str | None (Gradio can pass None)
- Add structlog logging for errors instead of exposing raw exceptions
- Update SPEC-22: mark as IMPLEMENTED, remove hardcoded line numbers
- Widen grep scope to match "no gr.Progress in codebase" criterion

docs/specs/SPEC-22-PROGRESS-BAR-REMOVAL.md

@@ -1,6 +1,6 @@
 # SPEC-22: Remove Unsupported gr.Progress from ChatInterface
 
-**Status:** READY FOR IMPLEMENTATION
+**Status:** IMPLEMENTED
 **Priority:** P3 (Technical debt cleanup)
 **Effort:** 15 minutes
 **PR Scope:** Single file fix
@@ -105,12 +105,12 @@ Refactoring from `ChatInterface` to `gr.Blocks` + `gr.Chatbot` just to support `
 
 ## Implementation Checklist
 
-- [ ] Open `src/app.py`
-- [ ] Remove `progress: gr.Progress = gr.Progress()` from `research_agent` signature
-- [ ] Remove all `progress(...)` calls (lines 192, 194, 204)
-- [ ] Add `show_progress="full"` to `gr.ChatInterface` constructor
-- [ ] Verify emoji status yields still present in orchestrator events
-- [ ] Run `make check`
+- [x] Open `src/app.py`
+- [x] Remove `progress: gr.Progress = gr.Progress()` from `research_agent` signature
+- [x] Remove all `progress(...)` calls from `research_agent`
+- [x] Add `show_progress="full"` to `gr.ChatInterface` constructor
+- [x] Verify emoji status yields still present in orchestrator events
+- [x] Run `make check`
 - [ ] Test locally: `uv run python src/app.py`
 
 ---
@@ -118,8 +118,8 @@ Refactoring from `ChatInterface` to `gr.Blocks` + `gr.Chatbot` just to support `
 ## Verification
 
 ```bash
-# Verify no gr.Progress usage
-grep -n "gr.Progress\|progress(" src/app.py
+# Verify no gr.Progress usage in codebase
+grep -rn "gr.Progress" src/
 
 # Should return empty (no matches)
 ```

src/app.py

@@ -5,6 +5,7 @@ from collections.abc import AsyncGenerator
 from typing import Any, Literal
 
 import gradio as gr
+import structlog
 
 from src.config.domain import ResearchDomain
 from src.orchestrators import create_orchestrator
@@ -13,6 +14,8 @@ from src.utils.exceptions import ConfigurationError
 from src.utils.models import OrchestratorConfig
 from src.utils.service_loader import warmup_services
 
+logger = structlog.get_logger(__name__)
+
 OrchestratorMode = Literal["advanced", "hierarchical"]  # Unified Architecture (SPEC-16)
 
 
@@ -126,9 +129,9 @@ def _validate_inputs(
 async def research_agent(
     message: str,
     history: list[dict[str, Any]],
-    domain: str = "sexual_health",
-    api_key: str = "",
-    api_key_state: str = "",
+    domain: str | None = None,
+    api_key: str | None = None,
+    api_key_state: str | None = None,
 ) -> AsyncGenerator[str, None]:
     """
     Gradio chat function that runs the research agent.
@@ -139,9 +142,9 @@ async def research_agent(
     Args:
         message: User's research question
         history: Chat history (Gradio format)
-        domain: Research domain
+        domain: Research domain (None defaults to "sexual_health")
         api_key: Optional user-provided API key (BYOK - auto-detects provider)
-        api_key_state: Persistent API key state (survives example clicks)
+        api_key_state: Persistent API key state (survives example clicks, can be None)
 
     Yields:
         Markdown-formatted responses for streaming
@@ -220,7 +223,8 @@ async def research_agent(
             yield "\n\n".join(response_parts)
 
     except Exception as e:
-        yield f"❌ **Error**: {e!s}"
+        logger.exception("research_agent_failed", error=str(e))
+        yield "❌ **Error**: Something went wrong. Please try again."
 
 
 def create_demo() -> tuple[gr.ChatInterface, gr.Accordion]: