The max_delete case allowlisted the tree aspect because the surviving extras after a partial --max-delete abort are deletion-order dependent. Under FASTSYNC_PARITY_STRICT a run where the orders coincide was reported as a stale entry (CI failure), while removing the entry made the order-dependent tree mismatch fail. Add a per-case 'compare_tree' flag: max_delete now asserts rc=25 plus the survivor count via extra_check instead of exact tree identity, so the allowlist can be empty. Burn-down reached zero.
- Recursive scans emit a directory entry for every traversed directory that
produced no transferred child, so empty source dirs (and dirs emptied by
filtering) are recreated like rsync; -m prunes them, --files-from/--list-only
never emit implicit dirs.
- A directory entry now replaces a destination regular file (rsync removes the
non-directory) instead of aborting; confined to the secure parent fd.
- -R --no-implied-dirs --files-from: stop refusing a listed file whose parent
is not listed; create the implied parent with default attributes (no source
metadata is captured for it), matching rsync 3.4.1.
- Differential gate: drop min_size/empty_dirs_recursive/dirs_plain allowlist
entries (dirs_plain now hands FastSync the same trailing-slash source as
rsync); add differential test for the files-from implied parent.
- Docs: -d row -> Parity, tally 108/24/24.
No wire change (PROTOCOL_VERSION stays 2.26.0).
Add tests/integration/test_differential_parity.py plus a shared
parity_harness.py and a data-driven parity_caveats.py allowlist. The gate
runs real rsync 3.4.1 and FastSync over the same corpora, compares the
destination trees (paths, hashes, symlink targets, modes, hard-link
grouping) and the normalized -i/--stats/--out-format output, and fails on
any difference not listed in the allowlist. Stale allowlist entries warn
(or fail under FASTSYNC_PARITY_STRICT=1) so the residual list shrinks.
Register parity/parity_ci markers and wire a fast PR job (parity_ci) plus a
push-only full job (parity, strict) into .gitea/workflows/ci.yaml.
Document the gate and the allowlist workflow in tests/integration/README.md.