/compact: agent activity indicator fires immediately when next message is queued, making it look like the message was sent mid-compact #3915

Summary

When /compact is running and the user types and submits a new message, the message appears in BOTH the queued-message stack AND the main chat history, and the "working" activity indicator kicks on right away — as if the message had been sent to the LLM mid-compaction.

Actual behavior (verified)

Functionally this is correct: the agent does not actually receive or respond to the queued message until /compact finishes. The bug is purely visual / UX.

Expected

While /compact is still running, a newly typed message should:

• Stay visible only in the queued stack
• NOT appear duplicated in the main chat transcript
• NOT trigger the "working" / activity indicator

The activity indicator and transcript echo should only fire once /compact completes and the message is actually dispatched to the model.

Why this matters

Users currently believe their message was sent prematurely and either re-send it, cancel, or assume /compact silently failed. The deceptive UI undermines trust in /compact.