Agents spawned by handler were getting branches several commits behind
main. Two compounding causes: sync_project ran 'git pull --ff-only' in
the project root, which only moves whichever branch the root checkout
happens to be on — an agent parked on a feature branch left origin/*
stale (and the pull's 'no tracking information' failure degraded to an
easy-to-miss sync_note). Then worktree spawns cut new branches from the
root's HEAD, inheriting that stale state.
sync_project now fetches origin (refreshing origin/* regardless of the
checkout), re-pins origin/HEAD, and fast-forwards the checkout only when
it sits on the default branch — a diverged default branch still fails
loudly. New worktree branches are cut from origin/HEAD with --no-track
so they start at the remote default branch's tip and don't adopt it as
upstream.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01V7mF6qeryi9nJthaxYkfPm
`git worktree add <path> <branch>` only checks out an existing ref, so
spawning an agent on a fresh feature branch failed with `fatal: invalid
reference` (exit 128) — the branch spawn asks for never exists yet, since
spawn starts from the remote's latest state.
- Detect whether the branch exists; use `git worktree add -b` to create it
when it doesn't, and a plain checkout (git DWIMs remote tracking) when it does.
- Slugify the agent name for the worktree directory so free-form names (a PR
title) no longer put spaces/colons/parens in repo-root paths.
- Surface git's stderr via a WorktreeError instead of a bare "exit status 128";
spawn re-raises it as SpawnError.
Adds tests/test_worktree.py covering new-branch creation, existing-branch
checkout, slugification, the isolation guard, and the clear-error path.
Claude
0xWheatyz