feat: add config schema and loader with env var expansion

src/config/loader.test.ts

@@ -0,0 +1,71 @@
+import { describe, it, expect } from 'vitest';
+import { loadConfig } from './loader.js';
+import { writeFileSync, mkdirSync, rmSync } from 'fs';
+import { join } from 'path';
+import { tmpdir } from 'os';
+
+describe('loadConfig', () => {
+  const testDir = join(tmpdir(), 'flynn-test-config');
+
+  it('loads valid config from file', () => {
+    mkdirSync(testDir, { recursive: true });
+    const configPath = join(testDir, 'config.yaml');
+    writeFileSync(configPath, `
+telegram:
+  bot_token: "test-token"
+  allowed_chat_ids: [123456789]
+server:
+  port: 18800
+models:
+  default:
+    provider: anthropic
+    model: claude-sonnet
+`);
+
+    const config = loadConfig(configPath);
+
+    expect(config.telegram.bot_token).toBe('test-token');
+    expect(config.telegram.allowed_chat_ids).toContain(123456789);
+    expect(config.server.port).toBe(18800);
+    expect(config.models.default.provider).toBe('anthropic');
+
+    rmSync(testDir, { recursive: true });
+  });
+
+  it('expands environment variables', () => {
+    mkdirSync(testDir, { recursive: true });
+    const configPath = join(testDir, 'config.yaml');
+    process.env.TEST_BOT_TOKEN = 'env-token-value';
+    writeFileSync(configPath, `
+telegram:
+  bot_token: \${TEST_BOT_TOKEN}
+  allowed_chat_ids: [123]
+server:
+  port: 18800
+models:
+  default:
+    provider: anthropic
+    model: claude-sonnet
+`);
+
+    const config = loadConfig(configPath);
+
+    expect(config.telegram.bot_token).toBe('env-token-value');
+
+    delete process.env.TEST_BOT_TOKEN;
+    rmSync(testDir, { recursive: true });
+  });
+
+  it('throws on invalid config', () => {
+    mkdirSync(testDir, { recursive: true });
+    const configPath = join(testDir, 'config.yaml');
+    writeFileSync(configPath, `
+telegram:
+  bot_token: ""
+`);
+
+    expect(() => loadConfig(configPath)).toThrow();
+
+    rmSync(testDir, { recursive: true });
+  });
+});