merger-ai's local-checkout sync stashed under fusion-ai-merge-sync-<taskId>,
a label none of merger.ts's reclamation machinery matches — every path keys
off the fusion-merger-autostash: prefix. Those entries were never classified,
never subsumed-dropped, never age-swept, and never surfaced as orphans holding
work, so they accumulated indefinitely: six entries dating back a month were
found on one working tree, and their age made real lost work indistinguishable
from litter. merger-ai now labels through buildAutostashLabel, and the legacy
prefix stays recognized so already-leaked entries are reclaimed rather than
stranded in developers' stash lists.
Routing them into that machinery first required fixing what it does with
untracked files. A stash created with --include-untracked keeps them in a
third parent (<sha>^3) that git stash show omits, so an untracked-only stash
read as empty — and all three copies of the liveness check treated empty as
"subsumed, safe to drop". Every leaked ai-sync stash carried untracked files,
so the fix would otherwise have destroyed the work it was meant to reclaim.
Liveness now resolves through one authority, classifyStashContent, which reads
both sides, diffs untracked paths against <sha>^3 rather than the stash commit
(whose tree never contained them), and treats unreadable state as unknown and
therefore undroppable.
Age-based sweeping is left alone: it drops by timestamp without consulting
content, which is deliberate bounded retention and the backstop against this
same accumulation, not a safety gap.
Regression test uses real git — the defect lives in git's stash object model,
so a mocked git can neither express nor catch it — and asserts the invariant
across tracked-only, untracked-only, and mixed stashes in both live and
subsumed states. The mixed shape (tracked subsumed, untracked live) is the one
that silently lost work.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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