* filer_pb: build BFS child paths with FullPath.Child
A start path with a trailing slash produced "/dir//sub" for every
subdirectory, and the filer only trims a trailing slash, so those
listings came back empty and the walk stopped after the first level.
Claude-Session: https://claude.ai/code/session_01Jp9tXRpBv9gvh8fkaVFqxQ
* filer_pb: normalize the BFS start path
Entries directly under the start path were reported with the caller's
trailing slash, so filer.meta.backup wrote them under a directory the
incremental stream never names again.
Claude-Session: https://claude.ai/code/session_01Jp9tXRpBv9gvh8fkaVFqxQ
* filer_pb: walk a re-delivered directory only once in TraverseBfs
A directory handed back twice by a listing (a page-boundary race with
concurrent renames, or a store whose ordering misbehaves) was enqueued
twice; the second walk re-lists the same subtree and can keep the
traversal from ever terminating.
Claude-Session: https://claude.ai/code/session_01XH7iM88ZqWMEvsLB8tkWPQ
* filer_pb: fail a directory listing whose pagination stops advancing
A full page ending on the very name the cursor started from re-fetches
the same page forever; a store whose listing order does not advance past
the cursor turns any full-directory read into a silent infinite loop.
Return an error naming the stuck cursor instead.
Claude-Session: https://claude.ai/code/session_01XH7iM88ZqWMEvsLB8tkWPQ
* shell: skip foreign-collection manifests in fs.mergeVolumes
Every manifest chunk in the namespace was resolved, downloading its
manifest needle, even when the merge plan only touches one collection.
Sub-chunks live in the manifest's own collection, so a manifest on a
volume outside the plan's collections cannot reference a source volume;
skip it and spare a cluster-wide download pass that looks like a hang
after the real moves finish.
Claude-Session: https://claude.ai/code/session_01XH7iM88ZqWMEvsLB8tkWPQ
Chris Lu