fix(agent-loop): preserve deferred message boundaries

packages/core/agent/README.i18n.yaml

@@ -2,5 +2,5 @@
 # side as of the last confirmed-consistent state. Both languages carry equal authority;
 # after editing either side, bring the other along and re-record with:
 #   pnpm run verify-translation-pairing --write packages/core/agent/README.md
-README.md: d71ea99001d9e764265550e0b50f898e2da541ff
-README.zh.md: 8fea509eacbf22ae8616fdbb7c8ed4074d955528
+README.md: b9e7914ac2238b677e5c799db58ca54088140352
+README.zh.md: 1a88f0d2e4c4619defae95a4cbe49caec7768599

packages/core/agent/README.md

@@ -58,7 +58,7 @@ Turn and step boundaries and the model token stream are durable `session/event`
 
 The handle every plugin programs against:
 
-- `agent.send(input, options)` — the one delivery primitive over the (`target` × `wakeup`) matrix. `input` is the existing `UserMessageData { content, source }`, while `SendOptions` requires only the routing policy `target` and `wakeup`. It returns the accepted message's opaque `AgentMessageId`, which the message's `agent/inbox/enqueue`/`dequeue`/`discard` events carry so a caller can correlate a queued item with its lifecycle; enqueue also carries the resolved `queued | steering` placement so listeners never reconstruct acceptance-time routing from later state. `target: 'next-turn'` queues one independent FIFO item that, if admitted, becomes the sole ordinary prompt in its turn. `target: 'next-step'` with `wakeup: true` submits steering, while `target: 'next-step'` with `wakeup: false` injects durable context without running the model. The [one-send-one-turn Agent Note](../../../.agents/notes/implemented/simplification/2026-07-17-one-send-one-turn.md) owns the turn rationale.
+- `agent.send(input, options)` — the one delivery primitive over the (`target` × `wakeup`) matrix. `input` is the existing `UserMessageData { content, source }`, while `SendOptions` requires only the routing policy `target` and `wakeup`. The agent snapshots and freezes `input` before publication or queueing, so later caller or observer mutation cannot change the accepted message. It returns the accepted message's opaque `AgentMessageId`, which the message's `agent/inbox/enqueue`/`dequeue`/`discard` events carry so a caller can correlate a queued item with its lifecycle; enqueue also carries the resolved `queued | steering` placement so listeners never reconstruct acceptance-time routing from later state. `target: 'next-turn'` queues one independent FIFO item that, if admitted, becomes the sole ordinary prompt in its turn. `target: 'next-step'` with `wakeup: true` submits steering, while `target: 'next-step'` with `wakeup: false` injects durable context without running the model. The [one-send-one-turn Agent Note](../../../.agents/notes/implemented/simplification/2026-07-17-one-send-one-turn.md) owns the turn rationale.
 - `agent.followup(input)` — the `next-turn`/wakeup preset of `send()`: queue an ordinary follow-up turn and wake the driver.
 - `agent.steer(input)` — the `next-step`/wakeup preset: during prompt admission or an open turn, stage steering for the next safe boundary without dispatching `agent/prompt-submit`; outside that acceptance window, delegate to a woken follow-up. Admission failure leaves staged steering for retry or a later admitted prompt, while cancellation or disposal may discard it.
 - `agent.inject(input)` — the `next-step`/no-wakeup preset: append model-facing context without running the model; the next request sees a verbatim user-role message whose provenance is carried by the required `input.source`. During prompt admission or an open turn, injection waits in the outbox for the next safe boundary. Outside that acceptance window, it appends immediately without opening a turn; a context-only admission batch takes this fallback if admission closes without a turn, while context staged beside steering remains pending with it. Persistence reacts to `session/event` independently. Injection emits no `agent/inbox/*` event.

packages/core/agent/README.zh.md

@@ -58,7 +58,7 @@ Agent *创建* 由实现 `AgentFactory` 的插件（`dsh-agent-loop`）提供，
 
 每个插件面向的 handle：
 
-- `agent.send(input, options)`：覆盖（`target` × `wakeup`）矩阵的唯一投递原语。`input` 是既有的 `UserMessageData { content, source }`，而 `SendOptions` 只要求路由策略 `target` 与 `wakeup`。它返回被接受消息的不透明 `AgentMessageId`，由该消息的 `agent/inbox/enqueue`/`dequeue`/`discard` 事件携带，调用方可据此把排队项与其生命周期关联；入队事件还会携带解析出的 `queued | steering` 路由归类，使监听器无需从后续状态重建接收时的路由。`target: 'next-turn'` 排队一条独立 FIFO 项，获准后成为其轮次中唯一的普通提示词。`target: 'next-step'` 且 `wakeup: true` 提交 steering（中途引导），而 `target: 'next-step'` 且 `wakeup: false` 注入持久上下文，不运行模型。轮次原理由 [one-send-one-turn Agent Note](../../../.agents/notes/implemented/simplification/2026-07-17-one-send-one-turn.md)拥有。
+- `agent.send(input, options)`：覆盖（`target` × `wakeup`）矩阵的唯一投递原语。`input` 是既有的 `UserMessageData { content, source }`，而 `SendOptions` 只要求路由策略 `target` 与 `wakeup`。agent 会在发布或入队前为 `input` 创建快照并将其冻结，因此调用方或观察方后续的修改无法改变已接受的消息。它返回被接受消息的不透明 `AgentMessageId`，由该消息的 `agent/inbox/enqueue`/`dequeue`/`discard` 事件携带，调用方可据此把排队项与其生命周期关联；入队事件还会携带解析出的 `queued | steering` 路由归类，使监听器无需从后续状态重建接收时的路由。`target: 'next-turn'` 排队一条独立 FIFO 项，获准后成为其轮次中唯一的普通提示词。`target: 'next-step'` 且 `wakeup: true` 提交 steering（中途引导），而 `target: 'next-step'` 且 `wakeup: false` 注入持久上下文，不运行模型。轮次原理由 [one-send-one-turn Agent Note](../../../.agents/notes/implemented/simplification/2026-07-17-one-send-one-turn.md)拥有。
 - `agent.followup(input)`：`send()` 的 `next-turn`／wakeup 预设：排队一个普通后续轮次并唤醒驱动器。
 - `agent.steer(input)`：`next-step`／wakeup 预设：提示词接纳期间或轮次打开时，为下一个安全边界暂存 steering，且不分发 `agent/prompt-submit`；该接收窗口之外则委托给会唤醒的后续轮次。接纳失败会保留暂存的 steering，以供重试或之后获准的提示词使用，而取消或 dispose 可能丢弃它。
 - `agent.inject(input)`：`next-step`／不唤醒预设：追加面向模型的上下文而不运行模型；下一次请求会看到一条逐字的 user role 消息，其来源由必填的 `input.source` 携带。提示词接纳期间或轮次打开时，注入会在 outbox 中等待下一个安全边界。该接收窗口之外，它会立即追加而不开启轮次；如果接纳结束却未开启轮次，仅含上下文的接纳批次会采用这一回退，而与 steering 一同暂存的上下文则会随其继续待处理。持久化独立地响应 `session/event`。注入不发出 `agent/inbox/*` 事件。

packages/core/agent/src/types.ts

@@ -77,8 +77,8 @@ export function AgentMessageId(id: string): AgentMessageId {
 /**
  * One accepted {@link Agent.send} message, carried by the `agent/inbox/*` live
  * events. `id` is the value `send` returned to the caller, stable across this
- * message's enqueue, dequeue, and discard events. Its content and source are
- * the exact input values accepted by the agent.
+ * message's enqueue, dequeue, and discard events. The agent snapshots and
+ * freezes the accepted content and source before enqueue observers receive it.
  */
 export interface AgentMessage extends UserMessageData {
   /** The id `send` returned for this message. */
@@ -172,6 +172,7 @@ export interface Agent {
    *   immediately without opening a turn. If admission closes without a turn,
    *   a context-only boundary appends immediately; context staged beside
    *   steering remains pending with it.
+   * The agent snapshots and freezes `input` before publishing or queueing it.
    * @param input - model-facing content and its producer provenance.
    * @param options - target queue and wakeup decision.
    * @returns the accepted message's {@link AgentMessageId}, stable across its `agent/inbox/*` events.