feat: add official wechat session exchange boundary

apps/api/src/main.ts

@@ -1,9 +1,10 @@
 import "reflect-metadata";
-import { Controller, Get, Injectable, Module } from "@nestjs/common";
+import { Body, Controller, Get, Injectable, Module, Post } from "@nestjs/common";
 import { NestFactory } from "@nestjs/core";
 import { FastifyAdapter } from "@nestjs/platform-fastify";
 import type { NestFastifyApplication } from "@nestjs/platform-fastify";
 import { PrismaClient } from "@prisma/client";
+import { WechatAuthService } from "./wechat-auth.js";
 
 @Injectable()
 export class PrismaService extends PrismaClient {
@@ -20,7 +21,35 @@ export class HealthController {
   }
 }
 
-@Module({ controllers: [HealthController], providers: [PrismaService], exports: [PrismaService] })
+@Controller("public")
+export class PublicController {
+  @Get("brand")
+  brand(): { message: string } {
+    return { message: "public brand endpoint is ready" };
+  }
+
+  @Get("services")
+  services(): { message: string } {
+    return { message: "public services endpoint is ready" };
+  }
+}
+
+@Controller("customer/session")
+export class CustomerSessionController {
+  constructor(private readonly wechatAuth: WechatAuthService) {}
+
+  @Post("wechat")
+  async wechatLogin(@Body() body: { code?: string }): Promise<{ openid: string }> {
+    const session = await this.wechatAuth.exchangeCode(body.code ?? "");
+    return { openid: session.openid };
+  }
+}
+
+@Module({
+  controllers: [HealthController, PublicController, CustomerSessionController],
+  providers: [PrismaService, WechatAuthService],
+  exports: [PrismaService, WechatAuthService],
+})
 export class AppModule {}
 
 export async function createApp(): Promise<NestFastifyApplication> {