diff --git a/esphome/automation.py b/esphome/automation.py
index 0958e862a8..996181f50b 100644
--- a/esphome/automation.py
+++ b/esphome/automation.py
@@ -701,4 +701,7 @@ async def build_callback_automation(
     # data in the struct.
     if forwarder is None:
         forwarder = TriggerForwarder.template(templ)
+    # RawExpression for aggregate init — both forwarder and obj are codegen
+    # MockObjs (not user input), and there's no Expression type for positional
+    # aggregate initialization (StructInitializer uses named fields).
     cg.add(getattr(parent, callback_method)(cg.RawExpression(f"{forwarder}{{{obj}}}")))