Date Picker popup doesn't propagate shadow DOM events into the light DOM

[teetotum]

What is the issue with the HTML Standard?

It seems the input type="date" standard does not specify whether or not any DOM events (click, keydown, etc) originating in the picker popup shadow DOM should be created with composed = true.

General developer documentation regarding UA generated events inside shadow DOM suggests that such events should be observable by event listeners in the regular DOM (i.e. light DOM) and therefore composed = true.

All UA-dispatched UI events are composed (click/touch/mouseover/copy/paste, etc.).
https://developer.mozilla.org/en-US/docs/Web/API/Event/composed

A quick test with chrome and firefox showed that (in at least those two browsers) currently no shadow DOM events are propagated.

<input type="date" id="input" />
<script>
  const input = document.getElementById("input");
  input.addEventListener("keydown", (e) => { console.log("bubbling keydown " + e.key); });
  input.addEventListener("keydown", (e) => { console.log("capturing keydown " + e.key); }, { capture: true });
  input.addEventListener("click", (e) => { console.log("bubbling click"); });
  input.addEventListener("click", (e) => { console.log("capturing click"); }, { capture: true });
</script>

User expectation (I currently have a sample size of 1 (just myself)) is that the user interaction with the date picker popup is observable in the light DOM.
Are there any security concerns forbidding such a motion?

At the moment I'm not sure whether this is just a gap in the specification or should be treated as a bug in the tested browsers.

[annevk]

Behavior for internal shadow roots is not specified to this extent. Furthermore, form controls and definitely their pickers are UI which makes requiring uniform behavior not really tenable.