review fix: preserve idle waiter quiescence

.agents/notes/implemented/simplification/2026-07-17-one-send-one-turn.md

@@ -8,13 +8,13 @@ English | [中文](2026-07-17-one-send-one-turn.zh.md)
 
 An ordinary `Agent.send()` payload is one complete caller message. Opportunistically draining every waiting payload into one turn would make adjacent calls share a boundary according to driver timing: calls from one synchronous stack, neighboring microtasks, event listeners, and model callbacks could be grouped differently even though callers used the same API.
 
-An ordinary turn owns prompt admission, `turn/start`, `turn/end`, and the durability checkpoint. Combining messages would let a later ordinary message join an earlier message's model request instead of observing the earlier ordinary turn's closed result in the same session log, while mixed allowed and blocked prompts would require lifecycle states no caller explicitly requested.
+An ordinary turn contains prompt admission, `turn/start`, `turn/end`, and the durability checkpoint. Combining messages would let a later ordinary message join an earlier message's model request instead of observing the earlier ordinary turn's closed result in the same session log, while mixed allowed and blocked prompts would require lifecycle states no caller explicitly requested.
 
 `steer()` already expresses joining the active turn, while `inject()` records model-facing context without acting as an ordinary message. Implicit ordinary-send batching would make `send()` overlap both explicit operations instead of preserving a single meaning.
 
 ## Decision
 
-Each successful `send()` synchronously validates agent state, snapshots and freezes content, appends one independent FIFO item, and publishes `agent/queued`. The loop dequeues at most one ordinary item for each turn start. If two ordinary items are both claimed, the second ordinary turn starts only after the first ordinary turn ends and its durability checkpoint settles; broad cancellation, disposal, or a pre-start failure can discard an unstarted item without creating an empty turn.
+Each successful `send()` synchronously validates agent state, snapshots and freezes content, appends one independent FIFO item, and publishes `agent/queued`. The loop dequeues at most one ordinary item for each turn start. If two ordinary items both reach turn processing, the second ordinary turn starts only after the first ordinary turn ends and its durability checkpoint settles; broad cancellation, disposal, or a pre-start failure can discard an unstarted item without creating an empty turn.
 
 Prompt admission decides one message. An allowed prompt becomes that turn's `user/message`; a blocked prompt appends one durable `prompt/blocked` and ends that one-message turn as `rejected`. There are no mixed-batch or all-blocked-batch branches.
 
@@ -34,6 +34,6 @@ Running `steer()` appends to the active turn's steering FIFO. Idle `steer()` del
 
 ## Consequences
 
-Ordinary turn boundaries are deterministic, and a claimed FIFO successor observes the preceding claimed ordinary turn's closed session result after that turn's checkpoint settles; settlement does not mean a failed flush became durable. Several queued items can still run under one global `running` interval, and broad cancellation can discard the entire unstarted tail, so status and quiescence remain agent-wide observations rather than per-message results.
+Ordinary turn boundaries are deterministic, and a FIFO successor that reaches turn processing observes the preceding completed ordinary turn's closed session result after that turn's checkpoint settles; settlement does not mean a failed flush became durable. Several queued items can still run under one global `running` interval, and broad cancellation can discard the entire unstarted tail, so status and quiescence remain agent-wide observations rather than per-message results.
 
 Workloads that relied on coincidental ordinary-send batching make more model requests, incur more checkpoints, and may take longer to drain; FIFO queues may grow under sustained producers. Ordinary-send batching can return only through an explicit measured contract.