diff --git a/tfbpapi/virtual_db.py b/tfbpapi/virtual_db.py
index 5ac1178..2f5ca09 100644
--- a/tfbpapi/virtual_db.py
+++ b/tfbpapi/virtual_db.py
@@ -43,6 +43,7 @@
 from __future__ import annotations
 
 import logging
+import re
 from functools import lru_cache
 from pathlib import Path
 from typing import Any
@@ -580,7 +581,6 @@ def _register_all_views(self) -> None:
             if not self._is_comparative(repo_id, config_name):
                 self._enrich_raw_view(db_name)
 
-        # 5. Comparative expanded views (pre-parsed composite IDs)
         # 5. Comparative expanded views (pre-parsed composite IDs)
         for db_name, (repo_id, config_name) in self._db_name_map.items():
             repo_cfg = self.config.repositories.get(repo_id)
@@ -833,18 +833,26 @@ def qualify(col: str) -> str:
         if prop_result is not None:
             _derived_exprs, _prop_raw_cols = prop_result
             for expr in _derived_exprs:
-                # Detect CAST(<field> AS _enum_<key>) AS <key> patterns
-                # where <field> == <key> (in-place factor override)
-                if not expr.startswith("CAST("):
-                    continue
+                # Detect factor CAST expressions of the form:
+                # CAST(CAST(<field> AS VARCHAR) AS _enum_<key>) AS <key>
+                # where <field> == <key> (in-place factor override).
+                # The output column name is the last " AS <name>" token.
                 parts = expr.rsplit(" AS ", 1)
                 if len(parts) != 2:
                     continue
                 out_col = parts[1].strip()
-                # Check whether the source field has the same name as
-                # the output column (in-place override case)
-                cast_inner = parts[0][len("CAST(") :]
-                src_field = cast_inner.split(" AS ")[0].strip()
+                # Extract the innermost source field from the CAST chain.
+                # Handles both:
+                #   CAST(CAST(<field> AS VARCHAR) AS _enum_<key>)
+                #   CAST(CAST(CAST(<field> AS BIGINT) AS VARCHAR) AS _enum_<key>)
+                m = re.match(
+                    r"CAST\(CAST\((?:CAST\()?(\w+)(?:\s+AS\s+BIGINT\))?"
+                    r"\s+AS\s+VARCHAR\)\s+AS\s+_enum_\w+\)",
+                    parts[0],
+                )
+                if m is None:
+                    continue
+                src_field = m.group(1)
                 if src_field == out_col and out_col in all_parquet_cols:
                     # Find a unique _orig name
                     candidate = f"{out_col}_orig"
@@ -894,8 +902,16 @@ def add_col(col: str) -> None:
         # Add derived property expressions from the VirtualDB config
         if prop_result is not None:
             derived_exprs, prop_raw_cols = prop_result
-            # Ensure source columns needed by expressions are selected
-            for col in prop_raw_cols:
+            # Ensure source columns needed by expressions are selected.
+            # For external metadata datasets, restrict to columns physically
+            # present in the metadata parquet -- data columns must not bleed
+            # into the meta view.
+            allowed_raw_cols = (
+                [c for c in prop_raw_cols if c in actual_meta_cols]
+                if is_external
+                else prop_raw_cols
+            )
+            for col in allowed_raw_cols:
                 add_col(col)
             # Rewrite CAST expressions to use the _orig alias when the
             # source field was renamed to avoid collision.
@@ -1230,7 +1246,17 @@ def _resolve_property_columns(
                         card, config_name, mapping.field
                     )
                     self._ensure_enum_type(enum_type, levels)
-                    expressions.append(f"CAST({mapping.field} AS {enum_type}) AS {key}")
+                    # If all levels are integer-valued strings (e.g. '0',
+                    # '90'), the parquet column may be DOUBLE (e.g. 90.0).
+                    # Cast through BIGINT first to strip the decimal before
+                    # converting to VARCHAR so '90.0' becomes '90'.
+                    all_int = all(re.fullmatch(r"-?\d+", lv) for lv in levels)
+                    inner = (
+                        f"CAST({mapping.field} AS BIGINT)" if all_int else mapping.field
+                    )
+                    expressions.append(
+                        f"CAST(CAST({inner} AS VARCHAR)" f" AS {enum_type}) AS {key}"
+                    )
                 elif key == mapping.field:
                     # no-op -- column already present as raw col
                     pass