get_quota_project() does not respect GOOGLE_CLOUD_QUOTA_PROJECT env var

[JoshuaShunk]

Problem

get_quota_project() in src/auth.rs reads quota_project_id exclusively from ADC files (GOOGLE_APPLICATION_CREDENTIALS or ~/.config/gcloud/application_default_credentials.json). It does not check the GOOGLE_CLOUD_QUOTA_PROJECT environment variable.

This is inconsistent with all official Google client libraries (Python, Go, Java, Node.js, C#), which support GOOGLE_CLOUD_QUOTA_PROJECT as a standard override with higher priority than the credentials file. See Google's documentation on setting the quota project.

Impact

When gws is embedded in a third-party tool that provides its own OAuth token via GOOGLE_WORKSPACE_CLI_TOKEN, the x-goog-user-project header is still read from the user's local ADC file. If the user has gcloud configured for a different GCP project (common for developers working on their own GCP projects), API calls fail with errors like:

Gmail API has not been used in project <wrong-project> before or it is disabled.

There is no way to override this without modifying the user's ADC file.

Expected Behavior

get_quota_project() should check GOOGLE_CLOUD_QUOTA_PROJECT first, consistent with the precedence defined by Google:

1. Programmatic (client option)
2. GOOGLE_CLOUD_QUOTA_PROJECT environment variable
3. quota_project_id from credentials file

Related

• fix(client): For ADC, send x-goog-user-project header #215 — Added get_quota_project() and x-goog-user-project support
• fix(client): Move x-goog-user-project header to API requests only #242 — Moved the header to API requests only
• google-auth-library-python PR #1163 — Added GOOGLE_CLOUD_QUOTA_PROJECT support
• Google docs: Set the quota project

[JoshuaShunk]

I have a fix ready at JoshuaShunk/cli@fix/respect-google-cloud-quota-project — will open a PR once non-collaborator PRs are re-enabled (per #249). The change adds GOOGLE_CLOUD_QUOTA_PROJECT as the highest-priority source in get_quota_project(), includes tests, and passes fmt/clippy locally.