fix(backend): Wire up MCP config in session_manager send_message

- Ensure MCP config file is created before CLI calls
- Pass --mcp-config flag to Claude CLI for atomizer tools access
- Add mcp__atomizer-tools__* to allowed tools in user mode
- Enables canvas validate/execute/interpret intent tools

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

atomizer-dashboard/backend/api/services/session_manager.py

@@ -45,7 +45,13 @@ class SessionManager:
         self.store = ConversationStore()
         self.context_builder = ContextBuilder()
         self._cleanup_task: Optional[asyncio.Task] = None
-        self._lock = asyncio.Lock()
+        self._lock: Optional[asyncio.Lock] = None  # Created lazily in async context
+
+    def _get_lock(self) -> asyncio.Lock:
+        """Get or create the async lock (must be called from async context)"""
+        if self._lock is None:
+            self._lock = asyncio.Lock()
+        return self._lock
 
     async def start(self):
         """Start the session manager"""
@@ -82,7 +88,7 @@ class SessionManager:
         Returns:
             ClaudeSession object
         """
-        async with self._lock:
+        async with self._get_lock():
             # Resume existing session if requested and alive
             if resume_session_id and resume_session_id in self.sessions:
                 session = self.sessions[resume_session_id]
@@ -201,12 +207,20 @@ class SessionManager:
         # Build CLI arguments based on mode
         cli_args = ["claude", "--print"]
 
+        # Ensure MCP config exists for atomizer tools
+        mcp_config_path = ATOMIZER_ROOT / f".claude-mcp-{session_id}.json"
+        if not mcp_config_path.exists():
+            mcp_config = self._build_mcp_config(session.mode)
+            with open(mcp_config_path, "w") as f:
+                json.dump(mcp_config, f)
+        cli_args.extend(["--mcp-config", str(mcp_config_path)])
+
         if session.mode == "user":
             # User mode: Allow safe operations including report generation
             # Allow Write tool for report files (STUDY_REPORT.md, *.md in study dirs)
             cli_args.extend([
                 "--allowedTools",
-                "Read Write(**/STUDY_REPORT.md) Write(**/3_results/*.md) Bash(python:*)"
+                "Read Write(**/STUDY_REPORT.md) Write(**/3_results/*.md) Bash(python:*) mcp__atomizer-tools__*"
             ])
         else:
             # Power mode: Full access