refactor agent pre-step inbox lifecycle

packages/context/session-reference/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/context/session-reference/README.md
-README.md: 66df45b18df6d859239c8d3216d6c8b9fa61ab23
-README.zh.md: b59a98b86baf88f53429bc2409ad1776b1638736
+README.md: dec478467929fe20a9866bea29c6e1d03e4d6408
+README.zh.md: 420973cd786afe7db5f0c44ff5af7b9d2135c056

packages/context/session-reference/README.md

@@ -14,7 +14,7 @@ English | [中文](README.zh.md)
 
 Preparation calls `ctx.sessionQuery.readSurface()` once per distinct source and never rereads it after enqueue. It projects only direct-user `user/message`, direct-user `steering/message`, assistant text, and `user/message` checkpoints carrying the canonical `dsh-compact` source marker from the folded current surface. For a source prompt that already contains baked prefix context, projection reads only its model-hidden display content, preventing recursive snapshot propagation. Shadowed pre-compaction events, tools, reasoning, context, plugin-generated user messages other than marked compact checkpoints, and unfinished assistant chunks are excluded. A compacted source therefore contributes its latest checkpoint plus retained later conversation, not restored shadowed text.
 
-The context source is `{ kind: 'session-reference', version: 1, references }`; each reference records its source id and label, capture seq, compact presence, retained/omitted message counts, omitted UTF-8 bytes, and truncation state. The standard TUI preserves admission ownership without attaching context to the generic inbox record: outside the next-step acceptance window, a one-shot `agent/prompt-submit` wrapper adds the snapshot only to an allowed decision; during prompt admission or an open turn, `inject()` and `steer()` stage beside each other for the same safe boundary. The target log therefore records a sourced context `user/message` followed by the readable direct `user/message` or `steering/message`. Later source mutation, compaction, or deletion cannot change target replay.
+The context source is `{ kind: 'session-reference', version: 1, references }`; each reference records its source id and label, capture seq, compact presence, retained/omitted message counts, omitted UTF-8 bytes, and truncation state. When the agent is idle, the standard TUI installs a one-shot `agent/pre-step` wrapper that adds the snapshot only to an `enter` decision containing the claimed direct prompt. While the agent is running, it calls `inject()` immediately before `steer()`, placing both messages in the next-step inbox for the same later claim. The target log therefore records a sourced context `user/message` followed by the readable direct `user/message` or `steering/message`. Later source mutation, compaction, or deletion cannot change target replay.
 
 ## Configuration
 

packages/context/session-reference/README.zh.md

@@ -14,7 +14,7 @@
 
 准备阶段会对每个不同源调用一次 `ctx.sessionQuery.readSurface()`，入队后绝不重读。它仅投影折叠后当前表层中的用户直接发出的 `user/message`、用户直接发出的 `steering/message`、assistant 文本，以及 `user/message` 检查点；这类检查点携带规范 `dsh-compact` 源标记。对于已经包含固化前缀上下文的源提示词，投影只读取其对模型隐藏的显示内容，以防止快照递归传播。已遮蔽的压缩（compaction）前事件、工具、推理（reasoning）、上下文、除已标记 compact 检查点外的插件生成 user 消息，以及未完成的 assistant 分片均会被排除。因此，已压缩源只会提供最新检查点及其后保留的会话内容，不会还原已遮蔽的文本。
 
-上下文源为 `{ kind: 'session-reference', version: 1, references }`；每条引用会记录其源 id 与 label、捕获 seq、是否存在 compact、已保留／已省略消息数、已省略 UTF-8 字节数与截断状态。标准 TUI 在不把上下文附加到通用 inbox 记录的情况下保留接纳归属：next-step 接收窗口之外，一次性 `agent/prompt-submit` 包装层只为获准决策添加快照；提示词接纳期间或轮次打开时，`inject()` 与 `steer()` 会并排暂存到同一安全边界。目标日志因此会先记录一条带来源信息的上下文 `user/message`，再记录可读的直接 `user/message` 或 `steering/message`。后续源变更、压缩或删除都无法改变目标回放。
+上下文源为 `{ kind: 'session-reference', version: 1, references }`；每条引用会记录其源 id 与 label、捕获 seq、是否存在 compact、已保留／已省略消息数、已省略 UTF-8 字节数与截断状态。agent 空闲时，标准 TUI 会安装一次性的 `agent/pre-step` 包装层，只把快照添加到包含已领取直接提示词的 `enter` 决策。agent 运行时，它会紧接着调用 `inject()` 和 `steer()`，把两条消息放入 next-step inbox，等待后续同一次领取。目标日志因此会先记录一条带来源信息的上下文 `user/message`，再记录可读的直接 `user/message` 或 `steering/message`。后续源变更、压缩或删除都无法改变目标回放。
 
 ## 配置