In-review tasks showed other tasks' files in their "files changed"
list. Task branches fork from local main, but the base capture
measured merge-base(HEAD, origin/main) — when local main carried
merged-but-unpushed task commits, the recorded base rewound past
them, and after the post-merge rebase-and-push rewrote those SHAs,
baseCommitSha..HEAD permanently swept the predecessors' files into
the new task's diff.
Extract the capture into base-commit-capture.ts, measure local main
first (origin/main fallback) to match the contamination-base sites,
and add a real-git regression suite covering local-ahead-of-origin.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
68e52e3c35