Schema 15 queues ops with a sealed transaction, keeps the section image in
16 KiB chunks and payloads by hash, and runs the cache in WAL with full sync.
A keystroke on a 3000-paragraph page writes ~19 KB to the cache instead of
~13 MB; publishing reads 2 KiB of the section instead of three whole copies, and
idle polls read the header only. A moved remote is read once and the queue
replays over it, merging per object; keep-mine restores a remotely deleted
page. Schema-14 caches convert once behind a recovery archive and roll back on
any mismatch. The cache lab tools read the new schema.

Assisted-by: claude-opus-5.5
Assisted-by: claude-opus-5