Worktree spawns now fetch only. The agent's branch is cut from
origin/* and the root checkout - which may hold the operator's own
work - is never fast-forwarded, merged, or re-parked by a spawn. A
failed fetch on a worktree spawn is fatal instead of a silent note:
the contract is 'starts at the remote's latest push', and cutting a
branch from stale refs would break it quietly.
Hardening around the same contract: the branch start falls back
origin/HEAD -> origin/main -> origin/master when the head pin is
missing, and a stale agent/<name> branch left behind by a deleted
agent is reset to the remote tip (-B) instead of silently shadowing
it - while -B's refusal to move a branch checked out elsewhere keeps
in-flight agents protected. Root/subdir placements (schedule firings,
mise-init) keep the fast-forward behavior for their shared tree, as
does the explicit sync command.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01731mKtVzsfeT4Vi3TvkR48
Claude
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