Fix observer query summaries for UNION and parenthesized SQL

Strip leading parentheses before extracting the SQL operation so
queries like "(SELECT ... UNION ...)" are correctly identified as
SELECT instead of "(SELECT". Append a UNION suffix to summaries
when a UNION clause is detected.

Author: davegaeddert

plain-models/plain/models/otel.py

@@ -64,7 +64,9 @@ def extract_operation_and_target(sql: str) -> tuple[str, str | None, str | None]
     Returns: (operation, summary, collection_name)
     """
     sql_upper = sql.upper().strip()
-    operation = sql_upper.split()[0] if sql_upper else "UNKNOWN"
+
+    # Strip leading parentheses (e.g. UNION queries: "(SELECT ... UNION ...)")
+    operation = sql_upper.lstrip("(").split()[0] if sql_upper else "UNKNOWN"
 
     # Pattern to match quoted and unquoted identifiers
     # Matches: "quoted", `quoted`, [quoted], unquoted.name
@@ -92,6 +94,10 @@ def extract_operation_and_target(sql: str) -> tuple[str, str | None, str | None]
             collection_name = _clean_identifier(match.group(1))
             summary = f"{operation} {collection_name}"
 
+    # Detect UNION queries
+    if " UNION " in sql_upper and summary:
+        summary = f"{summary} UNION"
+
     return operation, summary, collection_name