Reviewer flagged a race left open by the streaming guard added in #2455:
getUserInput() arms onInputCallback and schedules an 800 ms goal
continuation timer; when /goal set takes the streaming branch (or any
extension/hook starts a turn inside that window), the timer fired
unchecked. The downstream onInputCallback resolved the main waiter with
a goal-continuation submission, submitInteractiveInput called
session.promptCustomMessage without a streamingBehavior, and the same
AgentBusyError the PR set out to fix resurfaced.
Make the continuation timer streaming-aware: at fire time, bail out
when session.isStreaming || isCompacting || hasPostPromptWork is true.
Reuses the auto-submit busy check loop mode already relies on (renamed
#isLoopAutoSubmitBlocked -> #isAutoSubmitBlocked since both flows have
the same notion of 'agent is busy, do not submit'). The next agent_end
in #handleGoalSessionEvent reschedules normally.
Fixes#2454