Claude Code: Fix A2A communication - add missing /a2a/jsonrpc endpoint

The A2A JSON-RPC endpoint was missing, causing all A2A communication
to fail with 404 errors. Added proper /a2a/jsonrpc POST endpoint that:
- Handles message/send method from other HuggingClaw agents
- Processes messages through the brain
- Returns proper JSON-RPC 2.0 responses
- Updates worker state during processing

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app.py

@@ -284,6 +284,133 @@ def get_agents():
     }]
 
 
+class A2AMessage(BaseModel):
+    """A2A message format."""
+    messageId: str
+    role: str
+    parts: list
+
+
+class A2AParts(BaseModel):
+    """A2A message parts."""
+    type: str
+    text: str
+
+
+class A2AParams(BaseModel):
+    """A2A request params."""
+    message: A2AMessage
+
+
+class A2ARequest(BaseModel):
+    """A2A JSON-RPC request format."""
+    jsonrpc: str = "2.0"
+    id: str
+    method: str
+    params: Optional[A2AParams] = None
+
+
+@app.post("/a2a/jsonrpc")
+async def a2a_jsonrpc(request: Request):
+    """
+    A2A JSON-RPC endpoint for agent-to-agent communication.
+
+    Handles message/send method from other HuggingClaw agents.
+    """
+    try:
+        # Parse JSON-RPC request
+        body = await request.json()
+        msg_id = body.get("id", "")
+        method = body.get("method", "")
+
+        # Handle message/send method
+        if method == "message/send":
+            params = body.get("params", {})
+            message_data = params.get("message", {})
+            parts = message_data.get("parts", [])
+
+            # Extract text from parts
+            user_message = ""
+            for part in parts:
+                if part.get("type") == "text" or part.get("kind") == "text":
+                    user_message = part.get("text", "")
+                    break
+
+            # Update worker state to processing
+            global _worker_state
+            _worker_state["current_state"] = "processing"
+            _worker_state["last_heartbeat"] = datetime.utcnow().isoformat() + "+00:00"
+
+            try:
+                # Process message through brain
+                from error_handlers import handle_brain_response
+                response_text = handle_brain_response(user_message)
+
+                # Reset state to idle after processing
+                _worker_state["current_state"] = "idle"
+
+                # Return A2A JSON-RPC success response
+                return JSONResponse({
+                    "jsonrpc": "2.0",
+                    "id": msg_id,
+                    "result": {
+                        "status": {
+                            "state": "completed",
+                            "message": {
+                                "parts": [{
+                                    "type": "text",
+                                    "kind": "text",
+                                    "text": response_text
+                                }]
+                            }
+                        }
+                    }
+                }, status_code=200)
+
+            except Exception as e:
+                # Reset state on error
+                _worker_state["current_state"] = "idle"
+                logger.error(f"[A2A] Brain processing failed: {e}")
+
+                # Return A2A error response
+                return JSONResponse({
+                    "jsonrpc": "2.0",
+                    "id": msg_id,
+                    "result": {
+                        "status": {
+                            "state": "failed",
+                            "message": {
+                                "parts": [{
+                                    "type": "text",
+                                    "text": f"Error: {str(e)}"
+                                }]
+                            }
+                        }
+                    }
+                }, status_code=200)
+
+        # Unknown method
+        return JSONResponse({
+            "jsonrpc": "2.0",
+            "id": msg_id,
+            "error": {
+                "code": -32601,
+                "message": f"Method not found: {method}"
+            }
+        }, status_code=200)
+
+    except Exception as e:
+        logger.error(f"[A2A] Request parsing failed: {e}")
+        return JSONResponse({
+            "jsonrpc": "2.0",
+            "id": "",
+            "error": {
+                "code": -32700,
+                "message": "Parse error"
+            }
+        }, status_code=400)
+
+
 # CRITICAL: Main block to ensure uvicorn.run() executes immediately
 # This ensures server binds to 0.0.0.0:7860 regardless of agent initialization
 if __name__ == "__main__":