feat(plugins): add runtime handshake boundary

src/k1link/web/app.py

@@ -32,6 +32,7 @@ from k1link.web.plugin_runtime import (
     PluginActionNotFoundError,
     PluginExecutionError,
     PluginNotFoundError,
+    PluginRuntimeUnavailableError,
 )
 from k1link.web.session_api import build_session_router
 
@@ -175,11 +176,17 @@ async def request_validation_error_handler(
 
 @app.get("/api/health")
 def health() -> dict[str, Any]:
+    runtime_health = plugin_environment.runtime_health
+    runtimes_ready = all(item["status"] == "ready" for item in runtime_health)
     return {
-        "ok": True,
-        "status": "ok",
+        "ok": runtimes_ready,
+        "status": "ok" if runtimes_ready else "degraded",
         "service": "mission-core-control-plane",
         "version": __version__,
+        "plugin_runtimes": {
+            "ready": sum(item["status"] == "ready" for item in runtime_health),
+            "total": len(runtime_health),
+        },
     }
 
 
@@ -199,6 +206,11 @@ def get_device_models() -> dict[str, Any]:
         raise HTTPException(status_code=500, detail=str(exc)) from exc
 
 
+@app.get("/api/v1/device-plugin-runtimes")
+def get_device_plugin_runtimes() -> dict[str, Any]:
+    return {"items": list(plugin_environment.runtime_health)}
+
+
 @app.post("/api/v1/device-plugins/{plugin_id}/actions/{action_id}")
 async def invoke_device_plugin_action(
     plugin_id: str,
@@ -216,6 +228,8 @@ async def invoke_device_plugin_action(
         raise HTTPException(status_code=400, detail=str(exc)) from exc
     except PluginExecutionError as exc:
         raise HTTPException(status_code=502, detail=str(exc)) from exc
+    except PluginRuntimeUnavailableError as exc:
+        raise HTTPException(status_code=503, detail=str(exc)) from exc
 
 
 @app.websocket("/api/v1/device-plugins/{plugin_id}/events")
@@ -232,7 +246,7 @@ async def device_plugin_events(websocket: WebSocket, plugin_id: str) -> None:
         return
     except (PluginNotFoundError, PluginActionNotFoundError):
         await websocket.close(code=1008, reason="Device plugin is not available")
-    except PluginExecutionError:
+    except (PluginExecutionError, PluginRuntimeUnavailableError):
         await websocket.close(code=1011, reason="Device plugin state stream failed")