test(#5413): scope resize snapshot to dropdown handler

tests/test_reasoning_chip_btw_fixes.py

@@ -344,12 +344,18 @@ class TestResizeHandlerSymmetry:
     def test_resize_repositions_reasoning_dropdown(self):
         # The global resize handler must handle both composerModelDropdown AND
         # composerReasoningDropdown to keep them aligned when the window resizes.
-        m = re.search(
+        handlers = re.findall(
             r"window\.addEventListener\(\s*['\"]resize['\"][\s\S]*?\}\s*\)\s*;",
             UI_JS,
         )
-        assert m, "window resize handler not found in ui.js"
-        handler = m.group(0)
+        handler = next(
+            (
+                block for block in handlers
+                if "composerModelDropdown" in block and "_positionModelDropdown" in block
+            ),
+            None,
+        )
+        assert handler, "composer model dropdown resize handler not found in ui.js"
         assert "composerReasoningDropdown" in handler, (
             "window resize handler must also re-position composerReasoningDropdown "
             "while it's open (symmetric with the existing model-dropdown branch)"