fix: Code quality improvements for v5.2.2 release

- Fix pagination bug using continuation_token instead of start_after
- Add stats caching to prevent blocking web apps
- Improve code formatting and type checking
- Add comprehensive unit tests for new features
- Fix test mock usage in object_listing tests

scripts/check_metadata.py

@@ -0,0 +1,101 @@
+#!/usr/bin/env python3
+"""Check which delta files are missing metadata."""
+
+import sys
+from pathlib import Path
+
+# Add src to path for imports
+sys.path.insert(0, str(Path(__file__).parent.parent / "src"))
+
+from deltaglider import create_client
+
+
+def check_bucket_metadata(bucket: str) -> None:
+    """Check all delta files in a bucket for missing metadata.
+
+    Args:
+        bucket: S3 bucket name
+    """
+    client = create_client()
+
+    print(f"Checking delta files in bucket: {bucket}\n")
+    print("=" * 80)
+
+    # List all objects
+    response = client.service.storage.list_objects(bucket=bucket, max_keys=10000)
+
+    missing_metadata = []
+    has_metadata = []
+    total_delta_files = 0
+
+    for obj in response["objects"]:
+        key = obj["key"]
+
+        # Only check .delta files
+        if not key.endswith(".delta"):
+            continue
+
+        total_delta_files += 1
+
+        # Get metadata
+        obj_head = client.service.storage.head(f"{bucket}/{key}")
+
+        if not obj_head:
+            print(f"❌ {key}: Object not found")
+            continue
+
+        metadata = obj_head.metadata
+
+        # Check for required metadata fields
+        required_fields = ["file_size", "file_sha256", "ref_key", "ref_sha256", "delta_size"]
+        missing_fields = [f for f in required_fields if f not in metadata]
+
+        if missing_fields:
+            missing_metadata.append({
+                "key": key,
+                "missing_fields": missing_fields,
+                "has_metadata": bool(metadata),
+                "available_keys": list(metadata.keys()) if metadata else [],
+            })
+            status = "⚠️  MISSING"
+            detail = f"missing: {', '.join(missing_fields)}"
+        else:
+            has_metadata.append(key)
+            status = "✅ OK"
+            detail = f"file_size={metadata.get('file_size')}"
+
+        print(f"{status} {key}")
+        print(f"    {detail}")
+        if metadata:
+            print(f"    Available keys: {', '.join(metadata.keys())}")
+        print()
+
+    # Summary
+    print("=" * 80)
+    print(f"\nSummary:")
+    print(f"  Total delta files: {total_delta_files}")
+    print(f"  With complete metadata: {len(has_metadata)} ({len(has_metadata)/total_delta_files*100:.1f}%)")
+    print(f"  Missing metadata: {len(missing_metadata)} ({len(missing_metadata)/total_delta_files*100:.1f}%)")
+
+    if missing_metadata:
+        print(f"\n❌ Files with missing metadata:")
+        for item in missing_metadata:
+            print(f"  - {item['key']}")
+            print(f"    Missing: {', '.join(item['missing_fields'])}")
+            if item['available_keys']:
+                print(f"    Has: {', '.join(item['available_keys'])}")
+
+        print(f"\n💡 Recommendation:")
+        print(f"  These files should be re-uploaded to get proper metadata and accurate stats.")
+        print(f"  You can re-upload with: deltaglider cp <local-file> s3://{bucket}/<path>")
+    else:
+        print(f"\n✅ All delta files have complete metadata!")
+
+
+if __name__ == "__main__":
+    if len(sys.argv) != 2:
+        print("Usage: python check_metadata.py <bucket-name>")
+        sys.exit(1)
+
+    bucket_name = sys.argv[1]
+    check_bucket_metadata(bucket_name)