Server
- /api/download/:id answers Range with a strong ETag ("<id>.<gen>") and honours
If-Range; a stale partial gets the whole current file (streamed, so Bun does
not re-apply the Range itself). Uploads get the same treatment.
- GET /api/download/:id/prepare never blocks: ready {gen,size,sha256,etag,ext},
working (server still fetching), legacy (HEVC / too long / cache offline),
failed. Recently refused prepares are remembered for 10 minutes.
Browser
- The OPFS worker saves in 8 MiB ranges, writes at the byte offset, flushes
each chunk, retries each chunk 6 times with backoff (30 s idle timeout) and
keeps the .part plus a .part.json sidecar naming the server copy it belongs
to. A changed copy restarts cleanly; the finished file is hashed once and
checked against the server's SHA-256.
- SaveQueue remembers unfinished saves and resumes them on start, online,
return to the foreground and every 2 minutes while visible; one at a time.
- Downloads shows live MB progress, 'Preparing on server', 'Verifying', and
paused saves with Resume and Cancel (confirmed).
- listVideos ignores the sidecars; new listPartials/discardPartial helpers.
Verified in Chromium through a connection-dropping proxy: paused at 8 MiB,
auto-resumed after a reload from byte 8388608, final SHA-256 matched.
