New user prompt disappears after opening a subagent from message history in Ultra multi-agent mode

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

Codex Desktop app version not captured. I can provide it if needed.

What subscription do you have?

Not provided.

What platform is your computer?

macOS on Apple Silicon (arm64).

What issue are you seeing?

In Ultra reasoning mode with multi-agent collaboration enabled, a newly submitted user guidance message can disappear from the main conversation view after opening a subagent from a historical message.

This occurs while the main task and its subagents are still actively running: I type a guidance message in the main composer and press Enter to send it. The message initially appears in the main conversation, then disappears after the navigation action below.

The issue is specific to the navigation path:

• After pressing Enter to send a new guidance message during active execution, clicking a subagent reference in an older/historical message opens that agent in the sidebar and causes the newly sent user message to disappear from the main transcript.
• Opening the same subagent directly from the sidebar does not cause the newly sent user message to disappear.

This makes the main conversation UI unreliable during multi-agent work. It is unclear from the UI whether the prompt merely became hidden or whether it was also lost from the active task context.

What steps can reproduce the bug?

1. Start a Codex Desktop task with Ultra reasoning and multi-agent collaboration enabled.
2. Let the task create at least one subagent, and keep the main task/subagents running.
3. While execution is still in progress, type a new user guidance message in the main composer and press Enter to send it.
4. Confirm that the newly sent user message appears in the main message area.
5. In an older/historical message, click the referenced subagent so that the subagent opens in the sidebar.
6. Observe that the user guidance message sent in step 3 disappears from the main conversation area.
7. Repeat the test, but open the same subagent directly from the sidebar instead of from the historical message.

What is the expected behavior?

Opening a subagent from either a historical message or the sidebar should not remove or hide any already-sent user message from the main conversation transcript.

Both navigation paths should preserve the same conversation state, including the most recently submitted guidance message.

Additional information

• The issue was observed specifically during Ultra-mode multi-agent collaboration.
• The direct-sidebar path acts as a control case: it opens the agent without causing the newly sent user message to disappear.
• No sensitive prompts, task IDs, repository paths, or logs are included in this report.