rebuild(stage-1): establish isolated application skeleton

next/backend/http/__init__.py

@@ -0,0 +1 @@
+"""HTTP delivery layer."""

next/backend/http/errors.py

@@ -0,0 +1,22 @@
+from __future__ import annotations
+
+import uuid
+
+from fastapi import FastAPI, Request
+from fastapi.responses import JSONResponse
+
+
+def install_error_handlers(application: FastAPI) -> None:
+    @application.exception_handler(Exception)
+    async def unexpected_error(_request: Request, _error: Exception) -> JSONResponse:
+        correlation_id = uuid.uuid4().hex
+        return JSONResponse(
+            status_code=500,
+            content={
+                "error": {
+                    "code": "internal_error",
+                    "message": "服务暂时不可用，请稍后重试。",
+                    "correlation_id": correlation_id,
+                }
+            },
+        )

next/backend/http/router.py

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+from fastapi import APIRouter
+
+from backend.http.routes.health import router as health_router
+
+api_router = APIRouter()
+api_router.include_router(health_router)

next/backend/http/routes/__init__.py

@@ -0,0 +1 @@
+"""Transport-only route modules."""

next/backend/http/routes/health.py

@@ -0,0 +1,17 @@
+from fastapi import APIRouter, Request
+from pydantic import BaseModel
+
+router = APIRouter(tags=["health"])
+
+
+class HealthResponse(BaseModel):
+    status: str
+    environment: str
+
+
+@router.get("/health", response_model=HealthResponse)
+def health(request: Request) -> HealthResponse:
+    return HealthResponse(
+        status="ok",
+        environment=request.app.state.settings.environment,
+    )