google-docs MCP: OAuth token not persisted between sessions (re-auth every terminal)

Summary

After upgrading to Claude Code 2.1.70, the google-docs MCP server requires Google OAuth consent approval on every new terminal session. Previously (2.1.56), authentication persisted across sessions.

Expected behavior

Authenticate once, token persists across terminal sessions.

Actual behavior

Every new terminal opens the Google OAuth consent screen in the browser. Must click "Allow" each time.

Evidence

The token cache directory exists but is empty — no token file is ever written:

$ ls -la ~/.config/google-drive-mcp/
total 0
drwxr-xr-x  2 craigfilek  staff  64 Mar  5 17:27 .
drwxr-xr-x 11 craigfilek  staff 352 Feb 22 19:33 ..

The OAuth client config exists at ~/.mcp-credentials/google-drive-credentials.json (created Feb 21), but the refresh/access token that should be cached in ~/.config/google-drive-mcp/ is never written.

Environment

• macOS (Darwin 24.6.0)
• Claude Code 2.1.70 (upgraded from 2.1.56 via Homebrew)
• Google Docs MCP (built-in)