parity: --info=mount/stats, --stats dir breakdown, --debug categories

--info=mount now prints rsync's mount-point skip line (matching rsync
3.4.1, which emits it for repeated -xx and drops the mount-point dir);
--info=stats enables the same block as --stats; -x is repeatable.
--stats counts traversed directories for the Number of files breakdown
even when no directory metadata is captured (-r without -t/-p).
--debug enables real output for flist/del/hash/deltasum/recv/filter/send
at their natural FastSync events (synthetic categories stay inert).

--stats and --debug rows keep their documented residual status.

tests/integration/test_parity_debug.py

@@ -0,0 +1,105 @@
+"""`--debug=FLAGS` natural-event categories (no-wire).
+
+FastSync maps the rsync `--debug` categories that correspond to a real event it
+already performs (``flist``, ``del``, ``hash``/``deltasum``, ``recv``,
+``filter`` and ``send``) onto debug output.  A normal run prints none of it.
+"""
+import os
+import sys
+
+import pytest
+
+sys.path.insert(0, os.path.dirname(__file__))
+from common import TEST_DATA_DIR, run_client, clean_dir, get_dest_received_dir, ServerManager
+
+
+def _make_tree(root):
+    clean_dir(root)
+    os.makedirs(os.path.join(root, "sub"))
+    with open(os.path.join(root, "a.txt"), "wb") as fh:
+        fh.write(b"alpha\n")
+    with open(os.path.join(root, "keep.log"), "wb") as fh:
+        fh.write(b"log\n")
+    with open(os.path.join(root, "sub", "b.txt"), "wb") as fh:
+        fh.write(b"beta\n")
+
+
+@pytest.mark.ci
+def test_debug_flist_and_send_emit_output(shared_server):
+    """`--debug=flist,send` produces category-tagged debug output."""
+    source = os.path.join(TEST_DATA_DIR, "dbg_src")
+    dest = os.path.join(TEST_DATA_DIR, "dbg_dst")
+    _make_tree(source)
+    clean_dir(dest)
+    result, _ = run_client(source, dest, flags=["-a", "--debug=flist,send"],
+                           port=shared_server.port)
+    assert result.returncode == 0, (result.stderr or result.stdout)[:300]
+    assert "flist: scanning" in result.stdout, result.stdout
+    assert "send: " in result.stdout, result.stdout
+
+
+@pytest.mark.ci
+def test_debug_filter_emits_excluded_entry(shared_server):
+    source = os.path.join(TEST_DATA_DIR, "dbg_filter_src")
+    dest = os.path.join(TEST_DATA_DIR, "dbg_filter_dst")
+    _make_tree(source)
+    clean_dir(dest)
+    result, _ = run_client(source, dest,
+                           flags=["-a", "--debug=filter", "--exclude=*.log"],
+                           port=shared_server.port)
+    assert result.returncode == 0, (result.stderr or result.stdout)[:300]
+    assert "filter: excluded keep.log" in result.stdout, result.stdout
+
+
+@pytest.mark.ci
+def test_debug_hash_and_recv_emit_on_incremental(shared_server):
+    source = os.path.join(TEST_DATA_DIR, "dbg_hash_src")
+    dest = os.path.join(TEST_DATA_DIR, "dbg_hash_dst")
+    _make_tree(source)
+    clean_dir(dest)
+    result, _ = run_client(source, dest,
+                           flags=["-a", "--incremental", "--checksum",
+                                  "--debug=hash,recv"],
+                           port=shared_server.port)
+    assert result.returncode == 0, (result.stderr or result.stdout)[:300]
+    assert "hash: " in result.stdout, result.stdout
+    assert "recv: " in result.stdout, result.stdout
+
+
+@pytest.mark.ci
+def test_debug_del_emits_deleted_path():
+    """`--debug=del` reports the paths the receiver actually removed.
+
+    A deletion-capable server is required (the shared fixture refuses
+    client-requested deletion)."""
+    source = os.path.join(TEST_DATA_DIR, "dbg_del_src")
+    dest = os.path.join(TEST_DATA_DIR, "dbg_del_dst")
+    _make_tree(source)
+    clean_dir(dest)
+    seeded = get_dest_received_dir(dest, source)
+    os.makedirs(seeded)
+    with open(os.path.join(seeded, "extra.tmp"), "wb") as fh:
+        fh.write(b"stale\n")
+    server = ServerManager()
+    server.start(extra_args=["--allow-super", "--allow-delete"])
+    try:
+        result, _ = run_client(source, dest, flags=["-a", "--delete", "--debug=del"],
+                               port=server.port)
+    finally:
+        server.stop()
+    assert result.returncode == 0, (result.stderr or result.stdout)[:300]
+    assert "del: " in result.stdout and "extra.tmp" in result.stdout, result.stdout
+    assert not os.path.exists(os.path.join(seeded, "extra.tmp"))
+
+
+@pytest.mark.ci
+def test_normal_run_has_no_debug_output(shared_server):
+    source = os.path.join(TEST_DATA_DIR, "dbg_quiet_src")
+    dest = os.path.join(TEST_DATA_DIR, "dbg_quiet_dst")
+    _make_tree(source)
+    clean_dir(dest)
+    result, _ = run_client(source, dest, flags=["-a"], port=shared_server.port)
+    assert result.returncode == 0, (result.stderr or result.stdout)[:300]
+    assert "[DEBUG]" not in result.stdout
+    assert "flist: scanning" not in result.stdout
+    assert "send: " not in result.stdout