Both agents work on other machines and push straight to git. A8 and B7
were pinned to 8cddc9f while main had already moved to 7f912f1, and
neither task said to pull first — branching from a stale checkout is how
merges revert other people's work.
Adds an explicit "update your local copy" section to A8 and B7: fetch,
reset to origin/main, record the actual HEAD as BASE_SHA rather than the
SHA printed in the document, and branch from fresh main.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>