add scanner metadata cache reuse and control flags

tests/test_scanner.py

@@ -3,6 +3,7 @@
 import os
 import tempfile
 import time
+import csv
 from datetime import datetime, timezone
 from pathlib import Path
 from unittest.mock import patch, MagicMock
@@ -17,6 +18,8 @@ from vlm.scanner import (
     categorize_file,
     scan_library,
     extract_metadata,
+    save_inventory_csv,
+    load_inventory_csv,
 )
 
 
@@ -698,6 +701,63 @@ class TestExtractMetadata:
             assert vf.duration_seconds is None
             assert vf.bitrate_kbps is None
 
+    def test_scan_library_with_metadata_disabled(self, tmp_path):
+        """Test that metadata extraction can be disabled for faster scans."""
+        movie_dir = tmp_path / "movie"
+        movie_dir.mkdir()
+
+        video_file = movie_dir / "test.mp4"
+        video_file.touch()
+
+        config = Config(library_root=tmp_path)
+
+        with patch('subprocess.run') as mock_run:
+            result = scan_library(tmp_path, config, include_video_metadata=False)
+
+        assert len(result) == 1
+        assert result[0].filename == "test.mp4"
+        assert result[0].resolution is None
+        assert result[0].codec is None
+        assert result[0].duration_seconds is None
+        assert result[0].bitrate_kbps is None
+        mock_run.assert_not_called()
+
+    def test_scan_library_reuses_cached_metadata_when_unchanged(self, tmp_path):
+        """Test unchanged files reuse metadata from previous inventory cache."""
+        movie_dir = tmp_path / "movie"
+        movie_dir.mkdir()
+        video_file = movie_dir / "test.mp4"
+        video_file.write_text("test")
+
+        original = VideoFile(
+            path=video_file,
+            filename=video_file.name,
+            size_bytes=video_file.stat().st_size,
+            modified_timestamp=datetime.fromtimestamp(video_file.stat().st_mtime, tz=timezone.utc),
+            category="movie",
+            resolution="1920x1080",
+            codec="h264",
+            duration_seconds=120.5,
+            bitrate_kbps=5000,
+        )
+
+        cache_file = tmp_path / "cached_inventory.csv"
+        save_inventory_csv([original], cache_file, tmp_path)
+        cached_entries = load_inventory_csv(cache_file)
+        metadata_cache = {str(vf.path): vf for vf in cached_entries}
+
+        config = Config(library_root=tmp_path)
+        with patch("subprocess.run") as mock_run:
+            result = scan_library(tmp_path, config, metadata_cache=metadata_cache)
+
+        assert len(result) == 1
+        scanned = result[0]
+        assert scanned.resolution == "1920x1080"
+        assert scanned.codec == "h264"
+        assert scanned.duration_seconds == 120.5
+        assert scanned.bitrate_kbps == 5000
+        mock_run.assert_not_called()
+
 
 
 class TestInventoryReports: