Phase 2.6 previously launched parallel claude -p sessions in the same
working directory, causing git race conditions and repository corruption.
Changes:
- Add Phase 2.55 (pre-flight safety checks): clean tree, plan file
tracking, scope fence overlap validation, stale worktree cleanup
- Rewrite Phase 2.6 with git worktree isolation: each parallel session
gets its own worktree and branch, merged back sequentially
- Add merge conflict detection and abort (no silent data loss)
- Add unconditional worktree cleanup (even on failure)
- Add hard rules 11-13 (worktree mandatory, cleanup, sequential merge)
- Session-scoped progress file naming for --session mode
- Update headless launch template with worktree support and cleanup trap
- Bump version to 1.5.0
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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