(feature) Add managed rsync verbosity for dry-runs

Add default dry-run rsync output flags so long-running dry-runs expose
file-list, progress, stats, and itemized change information in their
run-specific log files.

Avoid duplicating user-supplied itemize or --info arguments so operators
can still tune rsync output from global or host configuration.

src/pobsync/rsync.py

@@ -10,6 +10,9 @@ from pathlib import Path
 from typing import Callable, Sequence
 
 
+DEFAULT_DRY_RUN_OUTPUT_ARGS = ["--itemize-changes", "--info=flist2,progress2,stats2"]
+
+
 @dataclass(frozen=True)
 class RsyncResult:
     exit_code: int
@@ -44,6 +47,8 @@ def build_rsync_command(
     cmd: list[str] = [rsync_binary]
 
     cmd.extend(list(rsync_args))
+    if dry_run:
+        _append_default_dry_run_output_args(cmd)
 
     # includes/excludes: keep it simple for now:
     # - if includes are provided, user is responsible for correct rsync include logic.
@@ -116,3 +121,19 @@ def _terminate_process_group(process: subprocess.Popen) -> None:
     except subprocess.TimeoutExpired:
         os.killpg(process.pid, signal.SIGKILL)
         process.wait(timeout=10)
+
+
+def _append_default_dry_run_output_args(command: list[str]) -> None:
+    if not _has_itemize_arg(command):
+        command.append("--itemize-changes")
+    if not any(arg.startswith("--info=") for arg in command):
+        command.append("--info=flist2,progress2,stats2")
+
+
+def _has_itemize_arg(command: list[str]) -> bool:
+    for arg in command:
+        if arg == "--itemize-changes":
+            return True
+        if arg.startswith("-") and not arg.startswith("--") and "i" in arg:
+            return True
+    return False

src/pobsync_backend/tests/test_run_scheduled_config_source.py

@@ -93,6 +93,8 @@ class RunScheduledConfigSourceTests(SimpleTestCase):
         def fake_run_rsync(command, log_path, timeout_seconds, cancel_check=None):
             self.assertEqual(log_path, Path("/tmp/pobsync-dryrun/web-01/run-42/rsync.log"))
             self.assertEqual(timeout_seconds, 900)
+            self.assertIn("--itemize-changes", command)
+            self.assertIn("--info=flist2,progress2,stats2", command)
             log_path.parent.mkdir(parents=True, exist_ok=True)
             log_path.write_text("run 42\n", encoding="utf-8")
             return RsyncResult(exit_code=0, command=command)
@@ -110,6 +112,30 @@ class RunScheduledConfigSourceTests(SimpleTestCase):
         self.assertEqual(result["log"], "/tmp/pobsync-dryrun/web-01/run-42/rsync.log")
         self.assertEqual(result["timeout_seconds"], 900)
 
+    def test_dry_run_does_not_duplicate_custom_output_args(self) -> None:
+        config_source = FakeConfigSource()
+
+        def effective_config_for_host(host: str) -> dict:
+            config = FakeConfigSource.effective_config_for_host(config_source, host)
+            config["rsync"]["args_effective"] = ["--archive", "--itemize-changes", "--info=name1,stats2"]
+            return config
+
+        config_source.effective_config_for_host = effective_config_for_host
+
+        with patch("pobsync.commands.run_scheduled.run_rsync") as run_rsync:
+            run_rsync.return_value = RsyncResult(exit_code=0, command=["rsync"])
+            run_scheduled(
+                prefix=Path("/missing-prefix"),
+                host="web-01",
+                dry_run=True,
+                config_source=config_source,
+            )
+
+        command = run_rsync.call_args.args[0]
+        self.assertEqual(command.count("--itemize-changes"), 1)
+        self.assertNotIn("--info=flist2,progress2,stats2", command)
+        self.assertIn("--info=name1,stats2", command)
+
     def test_dry_run_reports_cancelled_rsync(self) -> None:
         def fake_run_rsync(command, log_path, timeout_seconds, cancel_check=None):
             self.assertTrue(cancel_check())