Function parseConfig

Parse Gmail server configuration from CLI arguments and environment.

CLI Arguments (all optional):

• --auth= Authentication mode (default: loopback-oauth) Modes: loopback-oauth, service-account, dcr
• --headless Disable browser auto-open, return auth URL instead
• --redirect-uri= OAuth redirect URI (default: ephemeral loopback)
• --dcr-mode= DCR mode (self-hosted or external, default: self-hosted)
• --dcr-verify-url= External verification endpoint (required for external mode)
• --dcr-store-uri= DCR client storage URI (required for self-hosted mode)
• --port= Enable HTTP transport on specified port
• --stdio Enable stdio transport (default if no port)
• --log-level= Logging level (default: info)
• --storage-dir= Directory for CSV file storage (default: .mcp-z/files)
• --base-url= Base URL for HTTP file serving (optional)

Environment Variables:

• GOOGLE_CLIENT_ID OAuth client ID (REQUIRED)
• GOOGLE_CLIENT_SECRET OAuth client secret (optional)
• AUTH_MODE Default authentication mode (optional)
• HEADLESS Disable browser auto-open (optional)
• DCR_MODE DCR mode (optional, same format as --dcr-mode)
• DCR_VERIFY_URL External verification URL (optional, same as --dcr-verify-url)
• DCR_STORE_URI DCR storage URI (optional, same as --dcr-store-uri)
• PORT Default HTTP port (optional)
• LOG_LEVEL Default logging level (optional)
• STORAGE_DIR Default storage directory (optional)
• BASE_URL Default base URL for file serving (optional)

OAuth Scopes (from constants.ts): openid https://www.googleapis.com/auth/userinfo.profile https://www.googleapis.com/auth/userinfo.email https://mail.google.com/