A full backup opened its repository at the start of a step and wrote the
catalog at the end of it, without the catalog lock. A per-user export or
restore that wrote the catalog in between could lose its entry, or the
snapshot could lose its own.
The final step now only stores the snapshot object and moves the run to a
new 'commit' phase. BackupService then records the snapshot under the
catalog lock, from a repository opened inside that lock; if the lock is
busy, the next step retries the commit. Repository::writeSnapshot() keeps
its old behaviour as putSnapshot() plus recordSnapshot().
TreeWalker walks one or more roots in a stable segment-wise order with
exclusions and resumes after a cursor; ParentCursor merge-joins the
previous snapshot in the same order. BackupRun no longer keeps a file
list or the parent's entries in memory or in its state.
Dev tooling via composer (phpunit, psalm, nextcloud/ocp); vendor/ is
mounted from outside the repository by a helper script. 28 unit tests
ported from the phase-0 spikes (round trips, corruption, wrong keys,
dedup, incremental runs, partial restore, tampering, object binding,
time-boxed steps, file changed between steps).
dillard