feat(grouping): Add helper to combine hints

src/sentry/grouping/enhancer/__init__.py

@@ -257,6 +257,46 @@ def _split_rules(
     )
 
 
+def _combine_hints(
+    variant_name: str,
+    frame_component: FrameGroupingComponent,
+    in_app_hint: str | None,
+    contributes_hint: str | None,
+) -> str | None:
+    """
+    Given possible in-app and contributes hints, determine the frame's final hint.
+    """
+    frame_type = "in-app" if frame_component.in_app else "system"
+
+    # In-app hints never apply to the system stacktrace, so even if the contributes hint is `None`,
+    # it's the one we want
+    if variant_name == "system":
+        return contributes_hint
+
+    # From here on out everything we're doing is for the app variant
+
+    # System frames never contribute to the app stacktrace, so if they've already been marked out of
+    # app, we don't care whether or not they're ignored (or un-ignored), because they weren't going
+    # to count anyway.
+    if frame_type == "system":
+        return in_app_hint
+
+    # If only one hint exists, return that one
+    if in_app_hint and not contributes_hint:
+        return in_app_hint
+    if contributes_hint and not in_app_hint:
+        return contributes_hint
+
+    # If neither hint exists, return None
+    if not in_app_hint and not contributes_hint:
+        return None
+
+    # Combine the hints in such as way that we get "marked in-app by xxx AND un-ignored by yyy" and
+    # "marked in-app by xxx BUT ignored by yyy"
+    conjunction = "and" if frame_component.contributes else "but"
+    return f"{in_app_hint} {conjunction} {contributes_hint}"
+
+
 def is_valid_profiling_matcher(matchers: list[str]) -> bool:
     for matcher in matchers:
         if not matcher.startswith(VALID_PROFILING_MATCHER_PREFIXES):
@@ -683,6 +723,8 @@ def assemble_stacktrace_component(
             else:
                 contributes = rust_frame.contributes
 
+            frame_component.update(contributes=contributes)
+
             hint = get_hint_for_frame(variant_name, frame, frame_component, rust_frame)
             if self.run_split_enhancements:
                 split_in_app_hint = (
@@ -696,7 +738,7 @@ def assemble_stacktrace_component(
                     variant_name, frame, frame_component, contributes_rust_frame, "contributes"
                 )
 
-            frame_component.update(contributes=contributes, hint=hint)
+            frame_component.update(hint=hint)
 
             # Add this frame to our tally
             key = f"{"in_app" if frame_component.in_app else "system"}_{"contributing" if frame_component.contributes else "non_contributing"}_frames"

tests/sentry/grouping/enhancements/test_hints.py

@@ -6,7 +6,7 @@
 import pytest
 
 from sentry.grouping.component import FrameGroupingComponent
-from sentry.grouping.enhancer import get_hint_for_frame
+from sentry.grouping.enhancer import _combine_hints, get_hint_for_frame
 
 
 @dataclass
@@ -431,3 +431,35 @@ def test_get_hint_for_frame(
         get_hint_for_frame(variant_name, frame, frame_component, rust_frame, desired_hint_type)  # type: ignore[arg-type]
         == expected_result
     )
+
+
+@pytest.mark.parametrize(
+    ["variant_name", "in_app", "contributes", "in_app_hint", "contributes_hint", "expected_result"],
+    [
+        ("app", True, True, in_app_hint, None, in_app_hint),
+        ("app", True, True, in_app_hint, unignored_hint, f"{in_app_hint} and {unignored_hint}"),
+        ("app", True, False, in_app_hint, ignored_hint, f"{in_app_hint} but {ignored_hint}"),
+        ("app", False, True, out_of_app_hint, None, out_of_app_hint),
+        ("app", False, True, out_of_app_hint, unignored_hint, out_of_app_hint),
+        ("app", False, False, out_of_app_hint, ignored_hint, out_of_app_hint),
+        ("system", True, True, None, None, None),
+        ("system", True, True, None, unignored_hint, unignored_hint),
+        ("system", True, False, None, ignored_hint, ignored_hint),
+        ("system", False, True, None, None, None),
+        ("system", False, True, None, unignored_hint, unignored_hint),
+        ("system", False, False, None, ignored_hint, ignored_hint),
+    ],
+)
+def test_combining_hints(
+    variant_name,
+    in_app,
+    contributes,
+    in_app_hint,
+    contributes_hint,
+    expected_result,
+):
+    frame_component = FrameGroupingComponent(in_app=in_app, contributes=contributes, values=[])
+    assert (
+        _combine_hints(variant_name, frame_component, in_app_hint, contributes_hint)
+        == expected_result
+    )