docs(parity): dir-time entry is record-only; empty dirs carried by STATUS_MKDIR

RSYNC_COMPAT.md

@@ -288,7 +288,7 @@ why plain `--append` works on the normal atomic path, not only with `--inplace`.
 | `--write-devices` | Write to devices as files | ❌ Divergent | Writes only into an existing char/block node under the confined receive root (`O_NOFOLLOW` + `O_NONBLOCK`); a missing, symlinked, FIFO-with-no-reader, non-device, or otherwise unusable destination is skipped with a warning rather than allowed or aborted. Deliberate confinement divergence from rsync's more permissive behavior |
 | `-U`, `--atimes` | Preserve access times | ✅ Parity | Captures the source access time (from the scanner's pre-read stat, so it is not clobbered by reading the file for transfer) and transmits it over the wire; the receiver restores it together with the mtime via `futimens`/`utimensat`. Implies metadata transmission (the times travel inside the shared metadata payload), but does not enable ownership application (that stays opt-in via the identity flags). Wire: `atime` fields on the metadata frame + a `preserve_atimes` config boolean; `PROTOCOL_VERSION` bumped **2.11.0 → 2.12.0** |
 | `-N`, `--crtimes` | Preserve create times | ❌ Divergent | Birth-times cannot be set by any portable filesystem call (`utimensat`/`futimens` only set atime/mtime), so this row is an explicit **Divergent** entry (Phase 7 Wave B). Capture + transmit stays: `statx(STATX_BTIME)` on Linux records the source birth time as a wire field; the receiver logs a debug note that it cannot be applied and continues — never failing the transfer and never pretending it worked. On platforms without `statx` it parses as a documented no-op (flag accepted; nothing is captured). Implies metadata transmission. Wire: new `crtime` fields + a `preserve_crtimes` config boolean; `PROTOCOL_VERSION` bumped **2.11.0 → 2.12.0** (see the Phase-4 metadata-time notes) |
-| `-O`, `--omit-dir-times` | Omit dirs from --times | ✅ Parity | Real modifier now that FastSync preserves directory times. With metadata on, the scanner captures every traversed source directory's mtime (and atime under `-U`) and the sender transmits them in trailing `STATUS_DIR_TIMES` frame(s) **after all file data and the optional delete manifest** (chunked at the receiver's `MAX_MANIFEST_ENTRIES` per-frame cap); a dir-time entry only RECORDS metadata and never creates the directory, so empty source directories stay untransferred. The receiver defers applying them until its delete / `--delay-updates` publication phases have committed, so writing or removing a child never clobbers a parent directory's mtime (rsync applies directory times at the end for exactly this reason). When `-O` is set (the boolean crosses the wire) the receiver does not apply any of them; without `-O` an `-a`/`--preserve` transfer now restores directory times (reversing the old "never preserves dir times" divergence). Wire change: the terminal `STATUS_DIR_TIMES` frame; `PROTOCOL_VERSION` bumped **2.16.0 → 2.17.0** |
+| `-O`, `--omit-dir-times` | Omit dirs from --times | ✅ Parity | Real modifier now that FastSync preserves directory times. With metadata on, the scanner captures every traversed source directory's mtime (and atime under `-U`) and the sender transmits them in trailing `STATUS_DIR_TIMES` frame(s) **after all file data and the optional delete manifest** (chunked at the receiver's `MAX_MANIFEST_ENTRIES` per-frame cap); a dir-time entry only RECORDS metadata and never creates the directory (an empty source directory is created by the separate `STATUS_MKDIR` entry the scanner now emits, and `-m/--prune-empty-dirs` suppresses that; the trailing dir-time simply re-applies the metadata). The receiver defers applying them until its delete / `--delay-updates` publication phases have committed, so writing or removing a child never clobbers a parent directory's mtime (rsync applies directory times at the end for exactly this reason). When `-O` is set (the boolean crosses the wire) the receiver does not apply any of them; without `-O` an `-a`/`--preserve` transfer now restores directory times (reversing the old "never preserves dir times" divergence). Wire change: the terminal `STATUS_DIR_TIMES` frame; `PROTOCOL_VERSION` bumped **2.16.0 → 2.17.0** |
 | `-J`, `--omit-link-times` | Omit symlinks from --times | ✅ Parity | Real modifier now that FastSync preserves symlink times. Symlink entries already carried their metadata on `STATUS_SYMLINK`; the receiver now applies it with **no-follow primitives only** (`utimensat(..., AT_SYMLINK_NOFOLLOW)`, plus best-effort `fchmodat(..., AT_SYMLINK_NOFOLLOW)` and policy-gated `fchownat(..., AT_SYMLINK_NOFOLLOW)`), so the link itself is stamped without ever dereferencing it, confined fd-relative below the authorized receive root. A symlink has no children, so the times are applied immediately at creation. When `-J` is set (the boolean crosses the wire) the receiver skips the timestamps (mode/ownership are unaffected); without `-J` an `-a`/`-l` transfer restores symlink mtimes. Wire change alongside `-O`: the shared `STATUS_DIR_TIMES` frame; `PROTOCOL_VERSION` bumped **2.16.0 → 2.17.0** |
 | `--super` | Receiver attempts super-user activities | ❌ Divergent | Safe-subset privilege model. `--super` permits the receiver to attempt already-confined super-user activities (ownership application, char/block device-node creation, `--write-devices`); `--no-super` forbids them even for root; `auto` keeps the historical best-effort attempt. **FastSync never elevates** — no `setuid`/`seteuid`/`setgid` — and `--super` never bypasses the confinement floor, so it diverges from rsync's real elevation. A server `--no-super` veto forces it off for every connection; a privileged standalone listener defaults off without `--allow-super`; daemon modules opt in with `client owner = yes` |
 | `--fake-super` | Store/recover privileged attrs via xattrs | ❌ Divergent | Records the resolved `uid:gid:mode:mtime_sec:mtime_nsec` in a reserved `user.fastsync.stat` xattr and immediately replays mode/times fd-relative, but **never performs a real `chown`** (the owner is recorded for a later privileged restore). The on-disk key and format are FastSync-native, not rsync's `user.rsync.%stat%`, so recordings are not interoperable with rsync — the same class as the native auth and batch formats. Implies metadata transmission; incompatible with `-s` |