Enforce explicit display max-length keyword binding

Co-authored-by: Shri Sukhani <shrisukhani@users.noreply.github.com>

Author: cursoragent

tests/test_display_helper_usage.py

@@ -1,4 +1,5 @@
 from pathlib import Path
+import ast
 
 import pytest
 
@@ -54,3 +55,25 @@ def test_key_formatting_helper_usage_is_centralized():
             helper_usage_files.add(relative_path)
 
     assert helper_usage_files == ALLOWED_KEY_FORMAT_CALL_FILES
+
+
+def test_key_formatting_helper_calls_use_explicit_max_length_keyword():
+    missing_max_length_keyword_calls: list[str] = []
+
+    for path in _python_files():
+        relative_path = path.relative_to(HYPERBROWSER_ROOT)
+        if relative_path not in ALLOWED_KEY_FORMAT_CALL_FILES:
+            continue
+        module = read_module_ast(path)
+        for node in ast.walk(module):
+            if not isinstance(node, ast.Call):
+                continue
+            if not isinstance(node.func, ast.Name):
+                continue
+            if node.func.id != "format_string_key_for_error":
+                continue
+            if any(keyword.arg == "max_length" for keyword in node.keywords):
+                continue
+            missing_max_length_keyword_calls.append(f"{relative_path}:{node.lineno}")
+
+    assert missing_max_length_keyword_calls == []