make meta.yml atomic and add a few things like schema_version, proper base and rsync.command

src/pobsync/commands/run_scheduled.py

@@ -3,8 +3,6 @@ from __future__ import annotations
 from pathlib import Path
 from typing import Any
 
-import yaml
-
 from ..config.load import load_global_config, load_host_config
 from ..config.merge import build_effective_config
 from ..errors import ConfigError
@@ -20,7 +18,7 @@ from ..snapshot import (
     snapshot_dir_name,
     utc_now,
 )
-from ..util import ensure_dir, realpath_startswith, sanitize_host
+from ..util import ensure_dir, realpath_startswith, sanitize_host, write_yaml_atomic
 
 
 def _host_backup_dirs(backup_root: str, host: str) -> HostBackupDirs:
@@ -56,8 +54,21 @@ def select_scheduled_base(dirs: HostBackupDirs) -> Path | None:
     return _find_latest_snapshot(dirs.manual)
 
 
-def write_meta(path: Path, data: dict[str, Any]) -> None:
+def _base_meta_from_path(base_dir: Path | None) -> dict[str, Any] | None:
-    path.write_text(yaml.safe_dump(data, sort_keys=False), encoding="utf-8")
+    if base_dir is None:
+        return None
+
+    kind = base_dir.parent.name
+    if kind not in ("scheduled", "manual"):
+        # Should not happen with current selection logic, but keep meta robust.
+        kind = "unknown"
+
+    return {
+        "kind": kind,
+        "dirname": base_dir.name,
+        "id": None,
+        "path": None,
+    }
 
 
 def run_scheduled(prefix: Path, host: str, dry_run: bool) -> dict[str, Any]:
@@ -158,31 +169,15 @@ def run_scheduled(prefix: Path, host: str, dry_run: bool) -> dict[str, Any]:
         incomplete_dir = dirs.incomplete / snap_name
         data_dir = incomplete_dir / "data"
         meta_dir = incomplete_dir / "meta"
-        
+
         ensure_dir(data_dir)
         ensure_dir(meta_dir)
 
         meta_path = meta_dir / "meta.yaml"
         log_path = meta_dir / "rsync.log"
 
-        meta: dict[str, Any] = {
+        # Pre-build command so we can record it in metadata.
-            "id": snap_id,
-            "host": host,
-            "type": "scheduled",
-            "label": None,
-            "status": "running",
-            "started_at": format_iso_z(ts),
-            "ended_at": None,
-            "base_snapshot": None,
-            "rsync": {"exit_code": None, "stats": {}},
-            "overrides": {"includes": [], "excludes": [], "base": None},
-        }
-
-        log_path.touch(exist_ok=True)
-        write_meta(meta_path, meta)
-
         dest = str(data_dir) + "/"
-
         cmd = build_rsync_command(
             rsync_binary=str(rsync_binary),
             rsync_args=list(rsync_args),
@@ -197,18 +192,38 @@ def run_scheduled(prefix: Path, host: str, dry_run: bool) -> dict[str, Any]:
             extra_includes=list(includes),
         )
 
+        meta: dict[str, Any] = {
+            "schema_version": 1,
+            "id": snap_id,
+            "host": host,
+            "type": "scheduled",
+            "label": None,
+            "status": "running",
+            "started_at": format_iso_z(ts),
+            "ended_at": None,
+            "duration_seconds": None,
+            "base": _base_meta_from_path(base_dir),
+            "rsync": {"exit_code": None, "command": cmd, "stats": {}},
+            # Keep existing fields for future expansion / compatibility with current structure.
+            "overrides": {"includes": [], "excludes": [], "base": None},
+        }
+
+        log_path.touch(exist_ok=True)
+        write_yaml_atomic(meta_path, meta)
+
         result = run_rsync(cmd, log_path=log_path, timeout_seconds=timeout_seconds)
 
         end_ts = utc_now()
         meta["ended_at"] = format_iso_z(end_ts)
+        meta["duration_seconds"] = int((end_ts - ts).total_seconds())
         meta["rsync"]["exit_code"] = result.exit_code
         meta["status"] = "success" if result.exit_code == 0 else "failed"
-        write_meta(meta_path, meta)
+        write_yaml_atomic(meta_path, meta)
 
         if not log_path.exists():
             meta["status"] = "failed"
             meta["rsync"]["exit_code"] = 99
-            write_meta(meta_path, meta)
+            write_yaml_atomic(meta_path, meta)
             return {
                 "ok": False,
                 "dry_run": False,

src/pobsync/util.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import os
 import re
+import tempfile
 from pathlib import Path
 from typing import Any
 
@@ -25,7 +26,6 @@ def sanitize_host(host: str) -> str:
     return host
 
 
-
 def ensure_dir(path: Path, mode: int = 0o750) -> None:
     path.mkdir(parents=True, exist_ok=True)
     try:
@@ -62,3 +62,60 @@ def to_json_safe(obj: Any) -> Any:
         return obj
     return str(obj)
 
+
+def write_yaml_atomic(path: Path, data: Any) -> None:
+    """
+    Write YAML to `path` atomically.
+
+    Strategy:
+      - Write to a temp file in the same directory
+      - fsync temp file
+      - os.replace(temp, path) (atomic on POSIX)
+      - fsync directory entry (best-effort)
+
+    This helps avoid partial/corrupt meta files on crashes.
+    """
+    # Local import to keep module load light; PyYAML is already a project dependency.
+    import yaml  # type: ignore[import-not-found]
+
+    parent = path.parent
+    parent.mkdir(parents=True, exist_ok=True)
+
+    tmp_fd: int | None = None
+    tmp_path: Path | None = None
+
+    try:
+        with tempfile.NamedTemporaryFile(
+            mode="w",
+            encoding="utf-8",
+            dir=str(parent),
+            prefix=path.name + ".",
+            suffix=".tmp",
+            delete=False,
+        ) as tf:
+            tmp_fd = tf.fileno()
+            tmp_path = Path(tf.name)
+            tf.write(yaml.safe_dump(data, sort_keys=False))
+            tf.flush()
+            os.fsync(tmp_fd)
+
+        os.replace(str(tmp_path), str(path))
+
+        # Best-effort directory fsync (helps durability across power loss on some FS)
+        try:
+            dir_fd = os.open(str(parent), os.O_DIRECTORY)
+            try:
+                os.fsync(dir_fd)
+            finally:
+                os.close(dir_fd)
+        except OSError:
+            pass
+
+    finally:
+        # If anything failed before replace(), try to clean up temp file
+        if tmp_path is not None and tmp_path.exists():
+            try:
+                tmp_path.unlink()
+            except OSError:
+                pass
+