Can't edit a message in a side chat (`/side`)

What version of the Codex App are you using (From “About Codex” dialog)?

Version 26.601.20914 • Released Jun 2, 2026

What subscription do you have?

Plus

What platform is your computer?

Darwin 21.6.0 arm64 arm

What issue are you seeing?

The last-sent message in a /side chat has an edit button on it, which can be clicked to edit the sent message's content (and "Cancel" / "Send" buttons appear within the message, as expected). But clicking "Send" results in a red "Failed to edit message" error (near the top of the app window), with the message still in edit mode and not sent.

What steps can reproduce the bug?

1. Open a /side chat and send a message
2. Click the edit button on the sent message, edit something, then click "Send"
3. Observe the error

What is the expected behavior?

The message is edited and resent

Additional information

_No response_