fix: enforce message snapshot invariants

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: 44b2f81f7630834f8992f30e707956d86beac20c
-README.zh.md: bec0524ebc575d382c1a70871b4cb252830499b5
+README.md: 9fe207d940ddc80153131c3d76c992804bb83773
+README.zh.md: c7975fe5e0368aa46253c47c15f04e12a24a3b7b

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(message, options)` — the one delivery primitive over the (`target` × `wakeup`) matrix. `message` is an already identified `UserMessage`; callers normally create it with `createUserMessage()` before routing begins. `SendOptions` owns only the `target` and `wakeup` policy. The agent detaches and freezes the complete value without minting or replacing its identity. The message's `agent/inbox/enqueue`/`dequeue`/`discard` events carry it so callers 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(message, options)` — the one delivery primitive over the (`target` × `wakeup`) matrix. `message` is an already identified `UserMessage`; callers normally create it with `createUserMessage()` before routing begins. `SendOptions` owns only the `target` and `wakeup` policy. The agent detaches and freezes the complete value without minting or replacing its identity. The message's `agent/inbox/enqueue`/`dequeue`/`discard` events carry it so callers can correlate a queued item with its lifecycle; enqueue and dequeue also carry the resolved `queued | steering` placement so repeated message identities retire from the correct FIFO. `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(message, options)`：覆盖（`target` × `wakeup`）矩阵的唯一投递原语。`message` 是已有标识的 `UserMessage`；调用方通常会在开始路由前使用 `createUserMessage()` 创建它。`SendOptions` 只持有 `target` 与 `wakeup` 策略。agent 会将完整值与输入分离并冻结，但不会生成或替换其标识。该消息的 `agent/inbox/enqueue`/`dequeue`/`discard` 事件会携带其 id，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(message, options)`：覆盖（`target` × `wakeup`）矩阵的唯一投递原语。`message` 是已有标识的 `UserMessage`；调用方通常会在开始路由前使用 `createUserMessage()` 创建它。`SendOptions` 只持有 `target` 与 `wakeup` 策略。agent 会将完整值与输入分离并冻结，但不会生成或替换其标识。该消息的 `agent/inbox/enqueue`/`dequeue`/`discard` 事件会携带其 id，调用方可据此把排队项与其生命周期关联；入队与出队事件还会携带解析出的 `queued | steering` 路由归类，使重复出现的消息标识能在正确的 FIFO 中完成结算。`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

@@ -248,11 +248,18 @@ declare module 'cordis' {
      * boundary, or steering drained between steps. Fires after the item leaves
      * its FIFO and before it becomes a durable message.
      * @param agent - the agent whose inbox item was claimed.
-     * @param message - the claimed message (matching the `id` from its `agent/inbox/enqueue`).
+     * @param message - the claimed message.
+     * @param placement - the FIFO that claimed this occurrence; together with
+     *   `message.id`, it matches the earliest outstanding enqueue in that FIFO.
      * Scope-filtered dispatch (`@deepseek-ai/dsh-scope`): agent-scoped listeners receive only that agent.
      * @mode emit
      */
-    'agent/inbox/dequeue'(this: Scoped<Agent>, agent: Agent, message: UserMessage): void
+    'agent/inbox/dequeue'(
+      this: Scoped<Agent>,
+      agent: Agent,
+      message: UserMessage,
+      placement: InboxPlacement,
+    ): void
     /**
      * Pending inbox items were dropped without delivering them, so every
      * enqueue occurrence receives exactly one terminal `agent/inbox/dequeue` OR

packages/core/agent/tests/invariant.spec.ts

@@ -60,7 +60,7 @@ describe('agent inbox invariants', () => {
     expect(() => {
       ctx.emit(at, 'agent/inbox/enqueue', agent, info(), 'queued')
       ctx.emit(at, 'agent/inbox/enqueue', agent, info(), 'steering')
-      ctx.emit(at, 'agent/inbox/dequeue', agent, info())
+      ctx.emit(at, 'agent/inbox/dequeue', agent, info(), 'queued')
       ctx.emit(at, 'agent/inbox/discard', agent, [info()])
     }).not.toThrow()
   })
@@ -68,7 +68,7 @@ describe('agent inbox invariants', () => {
   it('rejects a dequeue with no outstanding item', async () => {
     const ctx = await setup()
     const agent = mockAgent('i2')
-    expect(() => { ctx.emit(scopeTarget(agent, agent), 'agent/inbox/dequeue', agent, info()) })
+    expect(() => { ctx.emit(scopeTarget(agent, agent), 'agent/inbox/dequeue', agent, info(), 'queued') })
       .toThrow(/without a matching prior enqueue/)
   })