Two recall paths shared the hasRecalledForFirstTurn flag: the agent_start
subscription (maybeRecallOnAgentStart, fire-and-forget with an unawaited
background prompt rebuild) and beforeAgentStartPrompt (awaited before the
turn builds). When the event path consumed the flag first,
beforeAgentStartPrompt returned undefined and the recalled context reached
the model only if the background rebuild had already landed -- on a fast
turn it had not, so autoRecall intermittently never reached the model.
Make beforeAgentStartPrompt the sole injection path and drop the racing
agent_start recall.
Fixes#7568
roboomp
510661437f