Every navigation rebuilt the breadcrumb with one `GET /api/folders/{id}` per path
segment (a depth-D folder = D requests, each no-store) purely to label the trail.
Add an id→name cache, populated wherever a name is already known:
- every listing names its children, so `cacheFolder` records them, and
- `getFolder` records the folder it fetched.
`buildCrumbs` now reads names from the cache and only fetches the ids it hasn't
seen. During normal step-by-step navigation each ancestor was named by its
parent's listing, so the breadcrumb resolves with ZERO extra requests; only a
cold deep-link fetches its unknown ancestors (still in parallel). Folder renames
update the cache immediately so the trail stays correct.
The cache is a small LRU (cap 1000 — names are tiny) and is independent of the
listing cache (names survive a listing invalidation).
Validated: 3 new unit tests (listing populates child names, getFolder records,
rename overwrites) → 46 frontend tests green; npm run check; headless render of
the real files route (list + grid) — no errors.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01M8Vb9QHmLZnEMzHz7MrFy6
Claude
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