feat(teacher-bff): 完整实现 teacher-bff GraphQL 聚合层

包含 clients/graphql/middleware、health probes、shared-ts contracts 等

services/teacher-bff/src/main.ts

@@ -1,36 +1,62 @@
+// teacher-bff 入口（B1 裁决：P2 起 GraphQL Yoga）
+// 优雅关闭顺序（G9）：HTTP → Redis → gRPC → Tracer
 import "reflect-metadata";
 import { NestFactory } from "@nestjs/core";
+import type { NestExpressApplication } from "@nestjs/platform-express";
+import type { Application, Request, Response } from "express";
 import { AppModule } from "./app.module.js";
 import { GlobalErrorFilter } from "./shared/errors/global-error.filter.js";
 import { initTracer, shutdownTracer } from "./shared/observability/tracer.js";
 import { logger } from "./shared/observability/logger.js";
 import { env } from "./config/env.js";
 import { metricsRegistry } from "./shared/observability/metrics.js";
-import type { Request, Response } from "express";
+import { closeAllGrpcClients } from "./clients/grpc/grpc.factory.js";
 
 async function bootstrap(): Promise<void> {
   initTracer();
 
-  const app = await NestFactory.create(AppModule, {
+  const app = await NestFactory.create<NestExpressApplication>(AppModule, {
     logger: ["log", "error", "warn"],
   });
 
   app.useGlobalFilters(new GlobalErrorFilter());
   app.enableShutdownHooks();
 
-  // Prometheus 指标端点：不鉴权，供 Prometheus 抓取。
-  app.getHttpAdapter().get("/metrics", async (_req: Request, res: Response) => {
+  // Prometheus 指标端点：不鉴权，供 Prometheus 抓取
+  // 直接获取 Express 实例注册路由，避免 HttpAdapter 泛型类型不兼容
+  const expressApp = app.getHttpAdapter().getInstance() as Application;
+  expressApp.get("/metrics", async (_req: Request, res: Response) => {
     res.set("Content-Type", metricsRegistry.contentType);
     res.end(await metricsRegistry.metrics());
   });
 
   await app.listen(env.PORT);
-  logger.info({ port: env.PORT }, "Teacher BFF started");
+  logger.info(
+    {
+      port: env.PORT,
+      graphql: env.GRAPHQL_PATH,
+      devMode: env.TEACHER_BFF_DEV_MODE,
+      iamTarget: env.IAM_GRPC_TARGET,
+    },
+    "Teacher BFF started (GraphQL + gRPC downstream)",
+  );
 
-  process.on("SIGTERM", async () => {
-    await app.close();
-    await shutdownTracer();
-  });
+  // 优雅关闭（G9：HTTP → Redis → gRPC → Tracer）
+  const shutdown = async (signal: string) => {
+    logger.info({ signal }, "Shutting down Teacher BFF");
+    try {
+      await app.close(); // 触发 OnModuleDestroy（Redis quit）
+      closeAllGrpcClients(); // 关闭所有 gRPC channel
+      await shutdownTracer();
+      logger.info("Teacher BFF shutdown complete");
+    } catch (err) {
+      logger.error({ err }, "Error during shutdown");
+      process.exit(1);
+    }
+  };
+
+  process.on("SIGTERM", () => void shutdown("SIGTERM"));
+  process.on("SIGINT", () => void shutdown("SIGINT"));
 }
 
 bootstrap().catch((err: unknown) => {