The bug: fully-deduplicated snapshots (every chunk already in storage
from a prior run) had an empty snapshot_blobs table. The metadata-
export pipeline then dropped all blob/blob_chunks rows from the
exported database, leaving file_chunks references to chunks whose
blobs were no longer recorded. Restore fails on every file with
"chunk X not found in any blob".
Fix: at CompleteSnapshot time, run an INSERT OR IGNORE that links
every blob holding a chunk referenced by this snapshot's files into
snapshot_blobs. New blobs uploaded during the snapshot are already
recorded (no-op for them); dedup-referenced blobs are added.
The cleanup query in deleteOrphanedBlobs already restricts to
snapshot_blobs entries for the current snapshot — so once
snapshot_blobs is correctly populated, the exported database
contains the full set of blob/blob_chunks rows needed for restore.
Regression test: TestDedupOnlySnapshotRestores creates two
identical snapshots (the second uploads zero new blobs) and
restores the second. Without the fix, restore fails on every file.
sneak
132f7149ca