d218b3a39e
Ref-store damage (a deleted refs/heads/main, an interrupted ref update) can leave an
existing vault repo without a 'main' branch. The cycle's ensureBranch('docmost','main')
+ checkout then throw every poll ("pathspec 'main' did not match"), wedging the space
forever with no self-heal — ensureRepo only creates branches on a FRESH git init
(found via web-test corruption charter, reproduced deterministically).
Add VaultGit.ensureMainBranch() and call it in the cycle preflight (after
clearStaleGitLocks, before the branch setup): if 'main' is missing, re-create it from
the 'docmost' mirror branch (they track each other) else from HEAD. Same
wedge-forever family as D3-N3.
Verified on the stand: deleting refs/heads/main now self-heals (main restored, the
edit reaches the vault, 0 pathspec errors) — was wedged forever. Unit test (real temp
repo: delete main -> ensureMainBranch restores it from docmost). git-sync suite green (708).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>