The digest salts content with the path relative to root (portability, #1774),
but the stat-index memo was keyed by absolute path only — so the same file
hashed under two roots (which happens within one `--out` run) served whichever
digest was computed first, making file_hash order-dependent and poisoning the
persisted stat-index across runs. Store one digest per salt under a "hashes"
map; legacy un-salted "hash" entries are never trusted (recompute once). Digest
computation is byte-identical, so existing cache entries still hit.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>