🤖 fix: hide synthetic queued messages from the user queue UI

[ammar-agent]

Summary

Background bash monitor wake prompts (and other system-injected messages) no longer flash in the queued-message banner or leak into the composer: MessageQueue now tracks per-entry synthetic origin and all user-facing queue surfaces exclude synthetic entries.

Background

When a background bash monitor matched output while the owner session was actively streaming, the wake prompt was deliberately queued with queueDispatchMode: "tool-end" so it could preempt at the next tool boundary. The queue's synthetic: true flag was only used to re-tag the outgoing batch for transcript metadata — queued-message-changed emitted getMessages()/getDisplayText() verbatim. The raw system prompt ("A background bash monitor matched output. …") therefore appeared in the user queue banner until the next tool boundary flushed it, complete with Edit/Send-now affordances that could pull system text into the input box. The same gap affected every synthetic queue producer (goal continuations, workspace-turn follow-ups, compaction handler follow-ups) and restoreQueueToInput() on user interrupt.

Implementation

System vs user segregation now lives in the queue's data model:

• MessageQueue stores QueueEntry { text, synthetic } instead of bare strings. Dispatch (produceMessage) still joins all entries in order.
• The former getMessages()/getDisplayText() are replaced by explicitly named getUserMessages()/getUserDisplayText(), which exclude synthetic entries. The /compact and agent-skill rawCommand shortcuts only apply when no synthetic entry shares the queue, so rawCommand never misrepresents a mixed batch.
• AgentSession builds its queued-message-changed payload through a shared buildQueuedMessageChangedEvent() (used by both live emits and the reconnect replay snapshot), so both paths only expose user-authored entries.
• restoreQueueToInput() restores only user content; a synthetic-only queue is still cleared (canceling wake callbacks as before) but emits no restore-to-input event.

No schema or frontend changes needed: the wire format is unchanged, and the frontend's existing queuedMessages.length > 0 content check naturally hides synthetic-only queues.

Risks

Low-to-moderate: touches the queue snapshot every workspace uses for the queued banner, interrupt-restore, and reconnect replay. For all-user queues, behavior is byte-identical to before. The main behavioral change is intentional: synthetic entries disappear from display/restore surfaces while still dispatching. Covered by new unit tests for synthetic-only, mixed, and rawCommand-adjacent cases plus session-level event assertions.

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Generated with mux • Model: anthropic:claude-fable-5 • Thinking: high

[ammar-agent]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Already looking forward to the next diff.

Reviewed commit: a552803a3f

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