Class ConfigFileAuthBackend

src/runtime/config.ts:367–425

// ---------------------------------------------------------------------------
// ConfigFileAuthBackend – stores OAuth credentials inside config.json._auth
// ---------------------------------------------------------------------------

/**
 * Custom AuthStorageBackend that persists OAuth credentials to the `_auth`
 * field of config.json, keeping all configuration in a single file.
 */
export class ConfigFileAuthBackend implements AuthStorageBackend {
  constructor(private configPath: string) {}

  private ensureFile(): void {
    const dir = path.dirname(this.configPath);
    if (!fs.existsSync(dir)) {
      fs.mkdirSync(dir, { recursive: true });
    }
    if (!fs.existsSync(this.configPath)) {
      fs.writeFileSync(this.configPath, "{}", "utf-8");
    }
  }

  private readAuthJson(): string | undefined {
    this.ensureFile();
    try {
      const raw = fs.readFileSync(this.configPath, "utf-8");
      const config = JSON.parse(raw);
      if (config._auth && typeof config._auth === "object") {
        return JSON.stringify(config._auth);
      }
      return undefined;
    } catch {
      return undefined;
    }
  }

  private writeAuthJson(authJson: string): void {
    this.ensureFile();
    try {
      const raw = fs.readFileSync(this.configPath, "utf-8");
      const config = JSON.parse(raw);
      config._auth = JSON.parse(authJson);
      fs.writeFileSync(this.configPath, JSON.stringify(config, null, 2), "utf-8");
    } catch {
      // If config.json is unreadable, write a minimal file
      const config = { _auth: JSON.parse(authJson) };
      fs.writeFileSync(this.configPath, JSON.stringify(config, null, 2), "utf-8");
    }
  }

  withLock<T>(fn: (current: string | undefined) => LockResult<T>): T {
    const current = this.readAuthJson();
    const { result, next } = fn(current);
    if (next !== undefined) {
      this.writeAuthJson(next);
    }
    return result;
  }

  async withLockAsync<T>(fn: (current: string | undefined) => Promise<LockResult<T>>): Promise<T> {
    const current = this.readAuthJson();