Harden display helper max-length validation boundaries

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

Author: cursoragent

hyperbrowser/display_utils.py

@@ -1,12 +1,15 @@
-from hyperbrowser.type_utils import is_plain_string
+from hyperbrowser.type_utils import is_plain_int, is_plain_string
 
 _TRUNCATED_DISPLAY_SUFFIX = "... (truncated)"
 _DEFAULT_BLANK_KEY_FALLBACK = "<blank key>"
+_DEFAULT_MAX_DISPLAY_LENGTH = 200
 
 
 def normalize_display_text(value: object, *, max_length: int) -> str:
     if not is_plain_string(value):
         return ""
+    if not is_plain_int(max_length) or max_length <= 0:
+        max_length = _DEFAULT_MAX_DISPLAY_LENGTH
     try:
         sanitized_value = "".join(
             "?" if ord(character) < 32 or ord(character) == 127 else character

tests/test_display_utils.py

@@ -37,6 +37,15 @@ class _StringSubclass(str):
     assert normalize_display_text(_StringSubclass("value"), max_length=20) == ""
 
 
+def test_normalize_display_text_uses_default_length_for_non_int_max_length():
+    assert normalize_display_text("value", max_length="invalid") == "value"  # type: ignore[arg-type]
+
+
+def test_normalize_display_text_uses_default_length_for_non_positive_max_length():
+    assert normalize_display_text("value", max_length=0) == "value"
+    assert normalize_display_text("value", max_length=-10) == "value"
+
+
 def test_format_string_key_for_error_returns_normalized_key():
     assert format_string_key_for_error(" \nkey\t ", max_length=20) == "?key?"