The PreToolUse guard blocked ALL edits while in the main checkout — including files
outside the repo (auto-memory, /tmp, scratchpad). Now it only denies edits to files
under the main checkout's working tree; external files are allowed.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Multiple sessions sharing this one checkout clobbered each other (branch switches,
edits landing on the wrong branch). Enforce per-session isolation:
- worktree.bgIsolation=worktree + baseRef=fresh (native bg-session isolation)
- PreToolUse(Edit|Write|NotebookEdit) hook DENIES edits while in the main checkout
- SessionStart hook directs each session to EnterWorktree (fresh worktree, off main)
.claude/hooks/worktree-guard.sh detects main-vs-worktree via git-dir != git-common-dir.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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