Fix #1523: [Bug] timed_with_status decorator silently swallows exceptions and returns None

src/memos/utils.py

@@ -179,6 +179,7 @@ def wrapper(*args, **kwargs):
                 if fallback is not None and callable(fallback):
                     result = fallback(e, *args, **kwargs)
                     return result
+                raise
             finally:
                 elapsed_ms = (time.perf_counter() - start) * 1000.0
 

tests/test_utils_timing_exception_reraise.py

@@ -0,0 +1,59 @@
+"""Test that timed_with_status re-raises exceptions when no fallback is configured.
+
+Regression test for issue #1523: timed_with_status decorator silently swallowed
+exceptions and returned None when no fallback was provided, masking real errors.
+"""
+
+import pytest
+
+from memos.utils import timed_with_status
+
+
+class TestTimedWithStatusExceptionReraise:
+    """Verify that exceptions are re-raised when no fallback is configured."""
+
+    def test_exception_reraised_when_no_fallback(self):
+        """When no fallback is configured, exceptions should propagate to caller."""
+
+        @timed_with_status(log_prefix="test_func")
+        def failing_func():
+            raise ValueError("upstream error")
+
+        with pytest.raises(ValueError, match="upstream error"):
+            failing_func()
+
+    def test_exception_reraised_preserves_type(self):
+        """The re-raised exception should preserve its original type."""
+
+        class CustomError(Exception):
+            pass
+
+        @timed_with_status()
+        def custom_error_func():
+            raise CustomError("specific error")
+
+        with pytest.raises(CustomError, match="specific error"):
+            custom_error_func()
+
+    def test_fallback_still_works(self):
+        """When fallback is provided, it should still be called instead of re-raising."""
+
+        @timed_with_status(fallback=lambda exc, *args, **kwargs: "fallback_result")
+        def failing_with_fallback():
+            raise RuntimeError("error")
+
+        result = failing_with_fallback()
+        assert result == "fallback_result"
+
+    def test_no_implicit_none_return(self):
+        """Decorated function should never return None on exception without fallback."""
+
+        @timed_with_status()
+        def fail_and_return():
+            raise KeyError("missing key")
+
+        # Should raise, not return None
+        with pytest.raises(KeyError):
+            result = fail_and_return()
+            # This line should never execute
+            assert result is not None, "Function returned None instead of raising"