* Google: preserve Gemini CLI OAuth failure context
Port the diagnostics-only fix to the bundled Google OAuth implementation so user-facing setup errors explain why automatic Gemini CLI client-config discovery failed.
Constraint: #54289 may remove or gate automatic Gemini CLI credential extraction
Rejected: Change extraction consent behavior here | security/product decision belongs in #54289
Confidence: medium
Scope-risk: narrow
Tested: pnpm test -- extensions/google/oauth.test.ts
Tested: pnpm check
Tested: pnpm format:check extensions/google/oauth.credentials.ts extensions/google/oauth.test.ts
Not-tested: full pnpm test suite
* Google: clarify Gemini bundle fallback diagnostic comment
Keep the follow-up limited to the explanatory comment so it matches the diagnostic error preservation added around bundle traversal failures.
Constraint: comment-only cleanup after diagnostics port
Confidence: high
Scope-risk: narrow
Tested: pnpm format:check extensions/google/oauth.credentials.ts
Not-tested: tests not run; comment-only change
* fix: resolve OAuth test rebase conflict
96e1b8c3ba