The scan recorded a directory's ETag when it was *discovered* as a child of
another, not when its own contents were read. A scan that stopped early
therefore stored ETags for subtrees it had never listed; the next scan probed
those ETags, found them unchanged, and pruned folders whose contents had
never been seen. Their images never entered the catalog at all, and no later
scan would ever look again.
Each stack entry now carries the validator its parent reported, recorded only
once the directory has been listed. An interrupted scan re-reads that folder
next time — slower, and correct.
Two related fixes fall out. The scan root is now probed and recorded even
though no parent described it, without which the one-request no-op sync that
ETag pruning exists for could never fire at the root. And a pruned directory
keeps its recorded entry, rather than dropping out and forcing a full walk of
that subtree on the following scan.
Assisted-by: LLM
dtourolle
57f8d42a5c