Shard 4 still wedged after the first quarantine — the hang consistently follows
the branch-group fn-001 worktree tests (merge-routing, automerge-precedence,
promotion-gate, pr-sync, single-pr-e2e), with the engine vitest process dying
before printing a summary. These are the suites with known pre-existing
failures (per-task-derived derivation). Move the family to *.slow.test.ts —
the non-required engine-slow lane — alongside the worktree-invariants and
shared-branch-group files. Live-git coverage preserved via test:slow/test:all.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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