Based on analysis of a live migration (v1.2.42 -> v1.2.47):
1. Absolute worktree paths: Bash tool resets cwd between calls,
so relative cd .upgrade-worktree fails. Store PROJECT_ROOT and
WORKTREE as absolute paths, use them throughout.
2. Smarter tier assessment: discount files from skill merges when
counting — a fork with 3 skills and no other changes is Tier 2,
not Tier 3 just because 24 files changed.
3. Inter-skill conflict analysis: new "Skill Interactions" section
in the migration guide captures conflicts between applied skills
(duplicate declarations, conflicting env var handling).
4. Cleaner swap recipe: use git reset --hard to the upgrade commit
instead of git checkout -B intermediate branch. Backup tag
preserves rollback. Copy guide to /tmp before worktree removal.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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