When an OAuth invalid_grant error is encountered, Claude Code now proactively clears the stale refresh token from both the file-based and config-based credential stores, rather than leaving it to fail on every subsequent request. This should reduce repeated auth failures after token expiration.
Evidence
New invalid_grant detection and token clearing (search for "invalid_grant", "tengu_oauth_refresh_token_cleared_invalid_grant", "tengu_wif_user_oauth_refresh_token_cleared")
Strings lifted out of the shipped bundle, so the claim above can be checked against them.