fix(core): preserve GUID case in replica map validation (#880)

The _validate_guid function was forcing GUIDs to uppercase, causing
FID mismatches in downstream systems (e.g. RootIOHandler) that perform
case-sensitive comparisons against the file's original GUID.

Author: chrisburr

diracx-core/src/diracx/core/models/replica_map.py

@@ -103,17 +103,19 @@ def _validate_guid(value: str) -> str:
     """Validate GUID checksum format.
 
     The format is 8-4-4-4-12 hexadecimal digits with hyphens (UUID format).
+    The original case is preserved to avoid mismatches with downstream systems.
     Example: 6032CB7C-32DC-EC11-9A66-D85ED3091D71
     """
-    value = value.upper()
     if len(value) != 36:
         raise ValueError(
             f"GUID checksum must be 36 characters long (including hyphens), got {len(value)}: {value}"
         )
 
     # Validate UUID format: 8-4-4-4-12 with hyphens
     if not re.match(
-        r"^[0-9A-F]{8}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{4}-[0-9A-F]{12}$", value
+        r"^[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}$",
+        value,
+        re.IGNORECASE,
     ):
         raise ValueError(f"GUID checksum must follow format 8-4-4-4-12 (UUID): {value}")
 

diracx-core/tests/test_replica_map.py

@@ -112,17 +112,17 @@ def test_valid_guid_uppercase(self):
         )
 
     def test_valid_guid_lowercase(self):
-        """Test that valid lowercase GUID is normalized to uppercase."""
+        """Test that valid lowercase GUID is preserved as-is."""
         assert (
             _validate_guid("6032cb7c-32dc-ec11-9a66-d85ed3091d71")
-            == "6032CB7C-32DC-EC11-9A66-D85ED3091D71"
+            == "6032cb7c-32dc-ec11-9a66-d85ed3091d71"
         )
 
     def test_valid_guid_mixed_case(self):
-        """Test that valid mixed case GUID is normalized to uppercase."""
+        """Test that valid mixed case GUID is preserved as-is."""
         assert (
             _validate_guid("6032cb7C-32DC-ec11-9A66-d85eD3091d71")
-            == "6032CB7C-32DC-EC11-9A66-D85ED3091D71"
+            == "6032cb7C-32DC-ec11-9A66-d85eD3091d71"
         )
 
     def test_guid_wrong_length_raises_error(self):