Require string type for env header JSON input

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

Author: cursoragent

hyperbrowser/header_utils.py

@@ -39,7 +39,11 @@ def normalize_headers(
 
 
 def parse_headers_env_json(raw_headers: Optional[str]) -> Optional[Dict[str, str]]:
-    if raw_headers is None or not raw_headers.strip():
+    if raw_headers is None:
+        return None
+    if not isinstance(raw_headers, str):
+        raise HyperbrowserError("HYPERBROWSER_HEADERS must be a string")
+    if not raw_headers.strip():
         return None
     try:
         parsed_headers = json.loads(raw_headers)

tests/test_header_utils.py

@@ -36,6 +36,13 @@ def test_parse_headers_env_json_ignores_blank_values():
     assert parse_headers_env_json("   ") is None
 
 
+def test_parse_headers_env_json_rejects_non_string_input():
+    with pytest.raises(
+        HyperbrowserError, match="HYPERBROWSER_HEADERS must be a string"
+    ):
+        parse_headers_env_json(123)  # type: ignore[arg-type]
+
+
 def test_parse_headers_env_json_rejects_invalid_json():
     with pytest.raises(
         HyperbrowserError, match="HYPERBROWSER_HEADERS must be valid JSON object"