decomposer: generate deliverable files for Define the service contract and project architecture for the FastAPI endpoint monitoring service.; Implement the typed monitor CRUD API and concurrency-safe in-memory state according to the service design.; Implement secure on-demand endpoint checks with status updates, latency measurement, robust error handling, and redacted structured logs.; Add operational API endpoints and environment-driven runtime configuration to the monitoring service.; Create automated tests for the monitoring service.; Package the service with Docker and developer documentation.; Validate the complete project.

app/main.py

@@ -0,0 +1,50 @@
+import logging
+from contextlib import asynccontextmanager
+from typing import AsyncIterator
+
+from fastapi import FastAPI, HTTPException, Request
+from fastapi.exceptions import RequestValidationError
+from fastapi.responses import JSONResponse
+
+from app.api import router
+from app.checker import EndpointChecker
+from app.settings import Settings, get_settings
+from app.store import MonitorStore
+
+
+def configure_logging(level: str) -> None:
+    logging.basicConfig(level=level.upper(), format="%(message)s")
+
+
+def create_app(settings: Settings | None = None) -> FastAPI:
+    config = settings or get_settings()
+
+    @asynccontextmanager
+    async def lifespan(application: FastAPI) -> AsyncIterator[None]:
+        configure_logging(config.log_level)
+        application.state.store = MonitorStore()
+        application.state.checker = EndpointChecker(config)
+        yield
+
+    application = FastAPI(title="Endpoint Monitor", version="1.0.0", lifespan=lifespan)
+    application.include_router(router)
+
+    @application.exception_handler(HTTPException)
+    async def http_error(_request: Request, exc: HTTPException) -> JSONResponse:
+        if isinstance(exc.detail, tuple):
+            code, message = exc.detail
+        else:
+            code, message = "http_error", str(exc.detail)
+        return JSONResponse(status_code=exc.status_code,
+                            content={"error": {"code": code, "message": message}},
+                            headers=exc.headers)
+
+    @application.exception_handler(RequestValidationError)
+    async def validation_error(_request: Request, _exc: RequestValidationError) -> JSONResponse:
+        return JSONResponse(status_code=422, content={"error": {
+            "code": "validation_error", "message": "Request validation failed"}})
+
+    return application
+
+
+app = create_app()