Google Sheets output adapter blocked on OAuth complexity

[matthewod11-stack]

Description

Google Sheets output adapter was deferred from Phase 6 to Phase 7 due to OAuth complexity — consent screen setup, token refresh, and secure credential storage are non-trivial for a CLI tool.

Current State

• packages/output/ has output-json, output-csv, output-markdown, and output-notion adapters planned
• No output-sheets package exists yet
• Phase 6 (Output Adapters) is the current phase; Sheets was moved to Phase 7

Suggested Fix

• Implement Google OAuth 2.0 flow with PKCE for CLI (localhost redirect)
• Handle consent screen requirements (Google Cloud project, OAuth client ID)
• Implement token refresh and secure storage in ~/.sourcerer/credentials/
• Build output-sheets adapter conforming to the output adapter interface
• Add integration tests with a test spreadsheet

Verification

• pnpm build passes
• pnpm test passes
• OAuth flow completes end-to-end in local dev
• Candidate data writes to a Google Sheet correctly

Automation Hints

scope: packages/output/
do-not-touch: packages/core/src/types/, packages/scoring/
approach: add-new-adapter
risk: high
max-files-changed: 20
blocked-by: none
bail-if: Google API console requires organizational verification for OAuth scopes

Priority

Low