* fix(fs): route thumbnail writes through FSEntryStore
Add FSEntryStore.updateEntryThumbnailByUuid, which sets a thumbnail with
no owner check (callers authorize) and refreshes the entry cache, with an
optional expected-value guard.
The thumbnails extension's inline data: URL migration, its copy
duplication, and the legacy /update-fsentry-thumbnail endpoint now write
through it instead of raw UPDATEs, so cached entries stop serving the old
thumbnail. The migration validates the image like the upload path, awaits
the write, and only repoints a row that still holds the data URL; a read
that loses that race deletes its upload.
* fix(fs): report a thumbnail update by whether the row changed
updateEntryThumbnailByUuid returned the refreshed entry, which is null
when the cache misses and the replica hasn't seen the row yet. The
read-time migration took that null for a lost race and deleted the object
the row had just been pointed at. It now returns whether the UPDATE
changed a row; the cache refresh still runs after it.
* fix(thumbnails): duplicate a copied thumbnail with GetObject + PutObject instead of CopyObject
CopyObject names its source as `<bucket>/<key>` in a header, which skips
any path in the client's endpoint, so it can miss an object that
Bucket/Key requests reach. The copy handler now reads the source object
(still behind the HeadObject size bound) and writes it under the copy's
key with its content type.
* fix(thumbnails): check the GetObject length before buffering a copied thumbnail
The size check runs on a HEAD and the read on a separate GET, so an object
replaced in between was read whole into memory. Reject a GET response whose
length exceeds the cap and destroy its body before reading.
A copied fsentry kept its source's thumbnail pointer verbatim, so both
rows shared one S3 thumbnail object. fs.remove.node deletes the
pointed-to object, so the first removal among the sharers — e.g. the
remove performed by a replace-on-copy — broke every other sharer's
thumbnail. FSService already emits fs.copy.node for exactly this
reason (its doc comment describes the duplication), but the thumbnails
extension never subscribed to it.
Add the missing handler: S3-copy the thumbnail to a freshly minted key
and repoint the copied row, under the same only-keys-we-minted trust
rule as the read/remove paths. If the shared object is already gone
(pre-fix damage), null the pointer instead of leaving the row
advertising a thumbnail it doesn't have.
Daniel Salazar