feat(api): REST API with OpenAPI for other apps, behind Pireon OAuth

A REST adapter next to GraphQL (presenters/http) that calls the same
application services, so validation, permissions and domain errors are the
same: projects (members, board, stats, activity), issues (search, workflow,
assignee, release, links, comments, history), comments, releases and users.
Projects and issues can be addressed by id or key (WEB, WEB-12).

- Swagger UI at /api/docs, document at /api/docs-json and apps/api/openapi.json
  (rewritten by `nx serve api`, like schema.gql) for client generation.
- Every route but health/auth/webhook needs a Pireon token: the document
  declares Pireon OAuth2 (authorization code + PKCE, password) through the
  /api/auth/token proxy, and a bearer scheme for apps with their own client.
- configureApp() shares main.ts setup with the e2e, which now also covers REST.
- SWAGGER_ENABLED / OPENAPI_FILE config; docs 03/05 and library READMEs.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/api/src/app/config.schema.ts

@@ -33,4 +33,9 @@ export const configSchema = Joi.object({
 
   GRAPHQL_PLAYGROUND: Joi.boolean().default(true),
   GRAPHQL_SCHEMA_FILE: Joi.string().allow('').default('apps/api/schema.gql'),
+
+  // REST + OpenAPI for other apps: Swagger UI at /api/docs, JSON at /api/docs-json.
+  SWAGGER_ENABLED: Joi.boolean().default(true),
+  // Where to write the OpenAPI document on startup ('' = don't), like the GraphQL SDL.
+  OPENAPI_FILE: Joi.string().allow('').default('apps/api/openapi.json'),
 });

apps/api/src/app/configure.ts

@@ -0,0 +1,13 @@
+import { INestApplication, ValidationPipe } from '@nestjs/common';
+import { DomainErrorFilter } from '@task-stream/api/shared/presenters';
+import { setupOpenApi } from './openapi';
+
+/** Everything main.ts sets on the app, shared with the e2e tests. */
+export function configureApp(app: INestApplication): void {
+  app.setGlobalPrefix('api');
+  app.enableCors();
+  app.enableShutdownHooks();
+  app.useGlobalPipes(new ValidationPipe({ transform: true, whitelist: true }));
+  app.useGlobalFilters(new DomainErrorFilter());
+  setupOpenApi(app);
+}

apps/api/src/app/health.controller.ts

@@ -5,12 +5,19 @@ import {
   ServiceUnavailableException,
 } from '@nestjs/common';
 import { InjectConnection } from '@nestjs/mongoose';
+import {
+  ApiOkResponse,
+  ApiOperation,
+  ApiServiceUnavailableResponse,
+  ApiTags,
+} from '@nestjs/swagger';
 import { Public } from '@task-stream/api/identity/presenters';
 import { REDIS_CLIENT } from '@task-stream/api/shared/infrastructure';
 import Redis from 'ioredis';
 import { Connection } from 'mongoose';
 import { DataSource } from 'typeorm';
 
+@ApiTags('Health')
 @Controller('health')
 export class HealthController {
   constructor(
@@ -21,6 +28,13 @@ export class HealthController {
 
   @Public()
   @Get()
+  @ApiOperation({ summary: 'API and databases status' })
+  @ApiOkResponse({
+    schema: {
+      example: { status: 'ok', postgres: 'up', mongo: 'up', redis: 'up' },
+    },
+  })
+  @ApiServiceUnavailableResponse({ description: 'A database is down' })
   async check() {
     const checks = await Promise.allSettled([
       this.postgres.query('SELECT 1'),

apps/api/src/app/openapi.ts

@@ -0,0 +1,158 @@
+import { INestApplication } from '@nestjs/common';
+import { ConfigService } from '@nestjs/config';
+import { DocumentBuilder, SwaggerModule } from '@nestjs/swagger';
+import {
+  PIREON_BEARER,
+  PIREON_OAUTH,
+} from '@task-stream/api/identity/presenters';
+import { writeFileSync } from 'node:fs';
+import { join } from 'node:path';
+
+export const API_VERSION = '1.0.0';
+
+const DESCRIPTION = `
+REST API of **Pireon TaskStream** for other apps: projects, tickets (bugs, features,
+UI changes, tasks and QA), workflow, comments, relations and releases.
+
+### Authentication
+Every endpoint (except \`/auth\`, \`/health\` and the webhook) needs a **Pireon access
+token**, so any app or user that consumes it goes through Pireon's OAuth:
+
+- **Authorization Code + PKCE** against \`oauth.pireon.dev/oauth/authorize\`
+  (the "Authorize" button here uses it; register \`<api>/api/docs/oauth2-redirect.html\`
+  as a redirect URI of the client).
+- An app with its own Pireon OAuth client can get tokens from Pireon directly and
+  send them as \`Authorization: Bearer <token>\`.
+
+What you can see and change depends on your role in each project.
+
+### Writes are eventually consistent
+Commands answer \`{ id, key?, version }\` as soon as the event is stored. Reads come from
+a read model that catches up in milliseconds: a \`GET\` right after a write may still
+show the previous version (or 404 right after a create).
+
+### Real time
+For live updates use the GraphQL subscriptions at \`/graphql\` (graphql-ws).
+`.trim();
+
+/**
+ * Builds the OpenAPI document from the REST controllers, serves Swagger UI and
+ * (in development) writes it to OPENAPI_FILE so other apps can generate clients.
+ */
+export function setupOpenApi(app: INestApplication): void {
+  const config = app.get(ConfigService);
+  if (!config.get<boolean>('SWAGGER_ENABLED')) return;
+
+  const pireon =
+    config.get<string>('PIREON_BASE_URL') ?? 'https://oauth.pireon.dev';
+  const scopes = (config.get<string>('PIREON_SCOPES') ?? '')
+    .split(/[\s,]+/)
+    .filter(Boolean);
+  const scopeDocs = Object.fromEntries(
+    scopes.map((scope) => [
+      scope,
+      scope === 'users:read' ? 'Search Pireon users' : scope,
+    ]),
+  );
+  // Token requests go through the API's proxy: Pireon's /oauth/token has no
+  // CORS and the client secret stays on the server.
+  const tokenUrl = '/api/auth/token';
+
+  const document = SwaggerModule.createDocument(
+    app,
+    new DocumentBuilder()
+      .setTitle('Pireon TaskStream API')
+      .setDescription(DESCRIPTION)
+      .setVersion(API_VERSION)
+      .addServer('/', 'This server (the paths already include /api)')
+      .addOAuth2(
+        {
+          type: 'oauth2',
+          description: 'Pireon OAuth2 (Laravel Passport)',
+          flows: {
+            authorizationCode: {
+              authorizationUrl: `${pireon}/oauth/authorize`,
+              tokenUrl,
+              refreshUrl: tokenUrl,
+              scopes: scopeDocs,
+            },
+            ...(config.get<boolean>('PIREON_PASSWORD_GRANT')
+              ? {
+                  password: {
+                    tokenUrl,
+                    refreshUrl: tokenUrl,
+                    scopes: scopeDocs,
+                  },
+                }
+              : {}),
+          },
+        },
+        PIREON_OAUTH,
+      )
+      .addBearerAuth(
+        {
+          type: 'http',
+          scheme: 'bearer',
+          description: 'A Pireon access token obtained elsewhere',
+        },
+        PIREON_BEARER,
+      )
+      .addTag('Projects', 'Projects, members, board, stats and activity')
+      .addTag(
+        'Issues',
+        'Tickets: search, create, workflow, relations, comments',
+      )
+      .addTag('Comments', 'Edit and delete comments')
+      .addTag('Releases', 'Versions that group tickets')
+      .addTag('Users', 'The signed-in user and the Pireon directory')
+      .addTag('Auth', 'Pireon OAuth token proxy')
+      .addTag('Health', 'Liveness of the API and its databases')
+      .addTag('Webhooks', 'Called by Pireon')
+      .build(),
+  );
+
+  // Operations without a security requirement are the public ones (@Public():
+  // health, auth, webhook). Say so explicitly instead of leaving it undefined.
+  for (const path of Object.values(document.paths)) {
+    for (const operation of [
+      path.get,
+      path.post,
+      path.put,
+      path.patch,
+      path.delete,
+    ]) {
+      if (operation && !operation.security) operation.security = [];
+    }
+  }
+
+  const file = config.get<string>('OPENAPI_FILE');
+  if (file) {
+    writeFileSync(
+      join(process.cwd(), file),
+      JSON.stringify(document, null, 2) + '\n',
+    );
+  }
+
+  SwaggerModule.setup('api/docs', app, document, {
+    jsonDocumentUrl: 'api/docs-json',
+    yamlDocumentUrl: 'api/docs-yaml',
+    customSiteTitle: 'Pireon TaskStream API',
+    swaggerOptions: {
+      persistAuthorization: true,
+      initOAuth: {
+        clientId: config.get<string>('PIREON_CLIENT_ID') || undefined,
+        scopes,
+        usePkceWithAuthorizationCodeGrant: true,
+      },
+    },
+    // The Pireon look, as in the web app.
+    customCss: `
+      @import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;600;700&display=swap');
+      .swagger-ui, .swagger-ui .info .title, .swagger-ui .opblock-tag { font-family: Inter, system-ui, sans-serif; }
+      .swagger-ui .topbar { display: none; }
+      .swagger-ui .info .title { background: linear-gradient(100deg, #a347e1, #1879bf); -webkit-background-clip: text; background-clip: text; color: transparent; }
+      .swagger-ui .btn.authorize { color: #a347e1; border-color: #a347e1; }
+      .swagger-ui .btn.authorize svg { fill: #a347e1; }
+    `,
+  });
+}

apps/api/src/main.ts

@@ -1,22 +1,19 @@
-import { Logger, ValidationPipe } from '@nestjs/common';
+import { Logger } from '@nestjs/common';
 import { NestFactory } from '@nestjs/core';
-import { DomainErrorFilter } from '@task-stream/api/shared/presenters';
 import { AppModule } from './app/app.module';
+import { configureApp } from './app/configure';
 
 async function bootstrap() {
   // rawBody: needed to verify Pireon webhook signatures.
   const app = await NestFactory.create(AppModule, { rawBody: true });
-  app.setGlobalPrefix('api');
-  app.enableCors();
-  app.enableShutdownHooks();
-  app.useGlobalPipes(new ValidationPipe({ transform: true, whitelist: true }));
-  app.useGlobalFilters(new DomainErrorFilter());
+  configureApp(app);
 
   const port = process.env['PORT'] || 3000;
   await app.listen(port);
   Logger.log(
     `🚀 GraphQL: http://localhost:${port}/graphql (ws for subscriptions)`,
   );
+  Logger.log(`📘 REST:    http://localhost:${port}/api/docs (OpenAPI)`);
   Logger.log(`❤️  Health:  http://localhost:${port}/api/health`);
 }