feat: serialize public hardware execution

src/cognitive_agent/server.py

@@ -28,7 +28,10 @@ load_local_env(REPOSITORY_ROOT / ".env.auth", override=True)
 from cognitive_agent.auth import AuthConfig, AuthRuntime, verify_password  # noqa: E402
 from cognitive_agent.application.seat_service import SeatDemoService  # noqa: E402
 from cognitive_agent.application.gesture_bridge import GestureCapabilityBridge  # noqa: E402
-from cognitive_agent.infrastructure.can.hardware import HardwareSafetyError  # noqa: E402
+from cognitive_agent.infrastructure.can.hardware import (  # noqa: E402
+    HardwareBusyError,
+    HardwareSafetyError,
+)
 from cognitive_agent.infrastructure.llm.openai_responses import OpenAIIntentError  # noqa: E402
 
 
@@ -110,6 +113,16 @@ class SeatDemoHandler(BaseHTTPRequestHandler):
                         vehicle_id,
                     )
                 )
+            except HardwareBusyError as exc:
+                self._json(
+                    {
+                        "error": "hardware_busy",
+                        "message": str(exc),
+                        "retry_after_seconds": exc.retry_after_seconds,
+                    },
+                    HTTPStatus.CONFLICT,
+                    {"Retry-After": str(exc.retry_after_seconds)},
+                )
             except ValueError as exc:
                 self._json(
                     {"error": "invalid_request", "message": str(exc)},
@@ -189,6 +202,16 @@ class SeatDemoHandler(BaseHTTPRequestHandler):
                 simulation_fault=str(payload.get("simulation_fault", "normal")),
             )
             self._json(result, HTTPStatus.CREATED)
+        except HardwareBusyError as exc:
+            self._json(
+                {
+                    "error": "hardware_busy",
+                    "message": str(exc),
+                    "retry_after_seconds": exc.retry_after_seconds,
+                },
+                HTTPStatus.CONFLICT,
+                {"Retry-After": str(exc.retry_after_seconds)},
+            )
         except HardwareSafetyError as exc:
             self._json(
                 {"error": "hardware_safety_gate", "message": str(exc)},