feat(api): M4 - API Service with better-sqlite3 and robust type safety

apps/api/.eslintrc.json

@@ -0,0 +1,19 @@
+{
+  "extends": [
+    "eslint:recommended",
+    "plugin:@typescript-eslint/recommended"
+  ],
+  "parser": "@typescript-eslint/parser",
+  "parserOptions": {
+    "ecmaVersion": 2020,
+    "sourceType": "module",
+    "project": "./tsconfig.json"
+  },
+  "plugins": ["@typescript-eslint"],
+  "rules": {
+    "@typescript-eslint/no-explicit-any": "off",
+    "@typescript-eslint/no-unused-vars": ["error", { "argsIgnorePattern": "^_" }]
+  },
+  "ignorePatterns": ["dist", "node_modules", "test", "**/*.d.ts", "**/*.js"]
+}
+

apps/api/.gitignore

@@ -0,0 +1,21 @@
+# Build output
+dist
+*.tsbuildinfo
+
+# Dependencies
+node_modules
+
+# Environment
+.env
+.env.local
+
+# Database
+*.db
+*.db-journal
+
+# Test coverage
+coverage
+
+# Logs
+*.log
+

apps/api/jest.config.js

@@ -0,0 +1,19 @@
+module.exports = {
+  preset: 'ts-jest',
+  testEnvironment: 'node',
+  roots: ['<rootDir>/test'],
+  testMatch: ['**/*.test.ts'],
+  collectCoverageFrom: [
+    'src/**/*.ts',
+    '!src/**/*.d.ts',
+  ],
+  coverageThreshold: {
+    global: {
+      branches: 80,
+      functions: 80,
+      lines: 80,
+      statements: 80,
+    },
+  },
+};
+

apps/api/package.json

@@ -6,12 +6,26 @@
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
   "scripts": {
-    "dev": "echo 'API dev server not yet implemented'",
-    "build": "echo 'API build not yet implemented'",
-    "test": "echo 'API tests not yet implemented'",
+    "dev": "tsx watch src/index.ts",
+    "build": "tsc",
+    "test": "jest",
     "lint": "eslint src"
   },
-  "dependencies": {},
-  "devDependencies": {}
+  "dependencies": {
+    "@togglekit/flags-core-ts": "workspace:*",
+    "fastify": "^4.25.2",
+    "@fastify/cors": "^8.5.0",
+    "better-sqlite3": "^9.2.2",
+    "zod": "^3.22.4"
+  },
+  "devDependencies": {
+    "@types/better-sqlite3": "^7.6.8",
+    "@types/node": "^20.11.0",
+    "tsx": "^4.7.0",
+    "typescript": "^5.3.3",
+    "jest": "^29.7.0",
+    "@types/jest": "^29.5.11",
+    "ts-jest": "^29.1.1"
+  }
 }
 

apps/api/src/app.ts

@@ -0,0 +1,79 @@
+/**
+ * Fastify application factory
+ * Creates and configures the Fastify server instance
+ */
+
+import Fastify, { FastifyInstance } from 'fastify';
+import cors from '@fastify/cors';
+import { configRoutes } from './routes/config';
+import { flagRoutes } from './routes/flags';
+import { evaluateRoutes } from './routes/evaluate';
+
+export interface AppOptions {
+  logger?: boolean;
+  cors?: {
+    origin: string | string[] | boolean;
+  };
+}
+
+/**
+ * Create and configure Fastify application
+ */
+export async function createApp(options: AppOptions = {}): Promise<FastifyInstance> {
+  const app = Fastify({
+    logger: options.logger ?? true,
+    disableRequestLogging: false,
+    requestIdHeader: 'x-request-id',
+  });
+
+  // Register CORS
+  await app.register(cors, {
+    origin: options.cors?.origin ?? true,
+    credentials: true,
+  });
+
+  // Health check endpoint
+  app.get('/health', async () => {
+    return { status: 'ok', timestamp: new Date().toISOString() };
+  });
+
+  // Register routes
+  await app.register(configRoutes);
+  await app.register(flagRoutes);
+  await app.register(evaluateRoutes);
+
+  // Global error handler
+  app.setErrorHandler((error, request, reply) => {
+    request.log.error(error);
+
+    // Handle validation errors
+    if (error.validation) {
+      return reply.status(400).send({
+        error: 'Bad Request',
+        message: 'Validation failed',
+        statusCode: 400,
+        details: error.validation,
+      });
+    }
+
+    // Default error response
+    const statusCode = error.statusCode ?? 500;
+    return reply.status(statusCode).send({
+      error: error.name || 'Internal Server Error',
+      message: error.message || 'An unexpected error occurred',
+      statusCode,
+    });
+  });
+
+  // 404 handler
+  app.setNotFoundHandler((request, reply) => {
+    return reply.status(404).send({
+      error: 'Not Found',
+      message: `Route ${request.method} ${request.url} not found`,
+      statusCode: 404,
+    });
+  });
+
+  return app;
+}
+