Add flag indicating mismatch between documentation and functionality

docs/generate_indices.py

@@ -56,6 +56,8 @@ def generate_rst_file(error: QueryErrorCode) -> None:
         "",
         f"**Message**: ``{error.message}``",
         "",
+        f"**Documentation / interface conformance**: ``{error.docs_interface_flag}``",
+        "",
         error.docs.strip()
         if error.docs.strip()
         else "**Description**: " + error.message,

docs/source/dev_docs/linter_development.rst

@@ -19,6 +19,10 @@ Each linter must override the `validate_tokens()` method and the `validate_query
 Best practices
 --------------
 - **Use standardized linter messages** defined in `constants.QueryErrorCode`.
+  Each message tuple includes a documentation/interface conformance flag:
+  ``DOCS_INTERFACE_OK`` when implementation behavior conforms to documented rules, and
+  ``DOCS_INTERFACE_MISMATCH`` when diagnostics enforce a documented rule that does not
+  fully match observed database behavior.
 - **Add details** in messages for guidance (e.g., invalid format, missing logic).
 - Ensure **valid token sequences** using the `VALID_TOKEN_SEQUENCES` dictionary.
 - Consider using **utility methods** provided by `linter_base.py`: