Update app/mapper.py

app/mapper.py

@@ -65,6 +65,8 @@ def save_dynamic_aliases() -> None:
 # ----------  schema versioning  ---------- #
 def ensure_schema_version(duck: duckdb.DuckDBPyConnection, df: pd.DataFrame) -> str:
     duck.execute("CREATE SCHEMA IF NOT EXISTS main")
+
+    # versioning metadata
     duck.execute("""
         CREATE TABLE IF NOT EXISTS main.schema_versions (
             version INTEGER PRIMARY KEY,
@@ -72,26 +74,40 @@ def ensure_schema_version(duck: duckdb.DuckDBPyConnection, df: pd.DataFrame) ->
             created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
         )
     """)
-    latest = duck.execute("SELECT * FROM main.schema_versions ORDER BY version DESC LIMIT 1").fetchone()
+
     new_signature = sorted(df.columns.tolist())
+    latest = duck.execute(
+        "SELECT version, columns FROM main.schema_versions ORDER BY version DESC LIMIT 1"
+    ).fetchone()
 
-    if latest:
+    if latest is None:
+        version = 1
+    else:
         latest_cols = sorted(json.loads(latest[1]))
         if latest_cols == new_signature:
+            # ✅ schema unchanged → reuse existing table
             return f"main.canonical_v{latest[0]}"
-        new_version = latest[0] + 1
-    else:
-        new_version = 1
-    duck.execute("INSERT INTO main.schema_versions (version, columns) VALUES (?, ?)",
-                 (new_version, json.dumps(new_signature)))
-    print(f"[schema] → canonical_v{new_version}")
-    table_name = f"main.canonical_v{new_version}"
+        version = latest[0] + 1
+
+    # ✅ record new schema version
+    duck.execute(
+        "INSERT INTO main.schema_versions (version, columns) VALUES (?, ?)",
+        (version, json.dumps(new_signature))
+    )
+
+    table = f"main.canonical_v{version}"
+
+    # ✅ create new table with ALL columns directly (safe)
+    col_defs = []
     for col in df.columns:
-        col_lower = col.lower()
         dtype = map_pandas_to_duck(col, df[col])
-        if col_lower not in {c.lower() for c in duck.execute(f"PRAGMA table_info('{table_name}')").df()['name']}:
-            duck.execute(f"ALTER TABLE {table_name} ADD COLUMN {col} {dtype}")
-            print(f"[schema] ➕ added {col}:{dtype} to {table_name}")
+        col_defs.append(f"{col} {dtype}")
+
+    duck.execute(f"CREATE TABLE {table} ({', '.join(col_defs)})")
+
+    print(f"[schema] ✅ created {table}")
+    return table
+
 
 def reconcile_latest_schema(duck: duckdb.DuckDBPyConnection) -> None:
     tables = [r[0] for r in duck.execute("""