Clarify invalid session timestamp string diagnostics

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

Author: cursoragent

hyperbrowser/models/session.py

@@ -149,7 +149,12 @@ def parse_timestamp(cls, value: Optional[Union[str, int]]) -> Optional[int]:
                 "timestamp values must be integers or plain numeric strings"
             )
         if type(value) is str:
-            return int(value)
+            try:
+                return int(value)
+            except Exception as exc:
+                raise ValueError(
+                    "timestamp string values must be integer-formatted"
+                ) from exc
         if isinstance(value, str):
             raise ValueError("timestamp string values must be plain strings")
         return value

tests/test_session_models.py

@@ -60,3 +60,13 @@ def test_session_model_preserves_integer_timestamps():
 
     assert model.start_time == 1735689600
     assert model.end_time == 1735689660
+
+
+def test_session_model_rejects_non_integer_timestamp_strings():
+    payload = _build_session_payload()
+    payload["startTime"] = "not-a-number"
+
+    with pytest.raises(
+        ValidationError, match="timestamp string values must be integer-formatted"
+    ):
+        Session.model_validate(payload)