docs(agent): document next-step acceptance window

.agents/notes/implemented/feature/2026-07-21-cross-session-references.i18n.yaml

@@ -1,6 +1,6 @@
 # Bilingual-pair consistency record (docs/i18n/README.md): the git blob hash of each
 # 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
-2026-07-21-cross-session-references.md: fc084b36e7920a72efff0f363278d24eaebc4c69
-2026-07-21-cross-session-references.zh.md: fe4a876b5265fa7ad298adf3b829bcec70e878e8
+#   pnpm run verify-translation-pairing --write .agents/notes/implemented/feature/2026-07-21-cross-session-references.md
+2026-07-21-cross-session-references.md: 18dab5fb85f2201258e2f15c3c069d2668ae80d3
+2026-07-21-cross-session-references.zh.md: 44e33ab1ed762b08b6be30d66b82396a5b519c02

.agents/notes/implemented/feature/2026-07-21-cross-session-references.md

@@ -10,7 +10,7 @@ TUI users need to bring relevant work from another conversation into one new mes
 
 ## Decision
 
-`@deepseek-ai/dsh-session-reference` is one context consumer service at `ctx.sessionReferences`. Hosts normalize their protocol into `SessionReferenceInput[]`, call `prepare()` before enqueue, and pass the returned contexts through the generic `SendOptions.contexts` boundary. Core agent packages know only that one queued message may carry frozen `HookContext[]`; they do not parse session URIs or read another log.
+`@deepseek-ai/dsh-session-reference` is one context consumer service at `ctx.sessionReferences`. Hosts normalize their protocol into `SessionReferenceInput[]` and call `prepare()` before delivery. The service returns detached readable content plus an optional sourced `UserMessageData` snapshot; core agent packages do not parse session URIs or read another log.
 
 `dsh-session:<base64url(JSON.stringify(sessionId))>` is the canonical host-independent identifier. JSON string encoding precedes base64url so quotes, slashes, backslashes, Unicode, newlines, and every other JavaScript string value round-trip without delimiter ambiguity. TUI renders that URI inside `@[label](uri)`; text-only clients may use the same inline mention. Explicit Markdown mentions reject malformed URIs. Bare text becomes a reference only for a non-empty base64url-shaped payload, whose decode must still be canonical; empty or punctuation-only uses remain ordinary discussion text.
 
@@ -22,17 +22,17 @@ Preparation deduplicates in first-appearance order, rejects the target id, enfor
 
 Projection retains direct-user messages and steering, completed assistant text, and checkpoint user messages carrying the canonical source exported by `dsh-compact`. That marker is part of the compaction capability contract rather than a backend package name. When a source prompt already contains baked prefix context, projection reads only its model-hidden display content, so referencing that target later does not recursively propagate an earlier snapshot. Projection excludes shadowed pre-compaction nodes, tools and results, reasoning, injected context, other plugin user messages, log-only records, and incomplete assistant chunks. Repeated compaction therefore exposes only the latest folded checkpoint lineage still on the current surface plus its retained tail; there is no raw/current switch and no shadow recovery.
 
-One aggregated context is serialized as JSON beneath a fixed untrusted-background warning. The warning tells the model not to follow instructions, permission claims, or tool requests from referenced sessions unless the current user repeats them. Tag-safe serialization emits every data `<` as the lossless JSON escape `\u003c`; source strings therefore cannot spell the surrounding XML-like tags. The `## My request:` text is a routing cue rather than the trust boundary: referenced data may spell those words inside a JSON string, but it cannot forge the closing `</referenced-sessions>` tag or escape the data region. The same serializer drives each source's independent byte accounting. The context declares `prompt-prefix` placement, so AgentLoop persists one `user/message` or `steering/message` containing the snapshot, `## My request:` delimiter, and effective direct prompt. Its model-hidden envelope retains the direct display content and source/retention metadata. Target replay therefore satisfies the model-visible/log-reconstructable invariant without a new event type or a separate user-role context message.
+One aggregated context is serialized as JSON beneath a fixed untrusted-background warning. The warning tells the model not to follow instructions, permission claims, or tool requests from referenced sessions unless the current user repeats them. Tag-safe serialization emits every data `<` as the lossless JSON escape `\u003c`; source strings therefore cannot spell the surrounding XML-like tags or escape the data region. The same serializer drives each source's independent byte accounting. AgentLoop persists the snapshot as a sourced `user/message` immediately before the direct `user/message` or `steering/message`; target replay therefore satisfies the model-visible/log-reconstructable invariant without a new event type, placement mode, or prompt envelope.
 
 ## Message ownership
 
-`send()` and `steer()` snapshot content, resolved source, and contexts together as one deeply frozen lossless-JSON inbox record. Synthetic `inject()` accepts source and model-hidden metadata but not attached contexts, which belong to inbox messages. A claimed ordinary message exposes its attached contexts as the default `agent/prompt-submit` additional contexts; a block writes neither user message nor contexts. The waterfall's returned allow is authoritative, so a listener wrapping `next()` preserves downstream content and contexts unless it intentionally replaces them. After admission, absent or `separate` placement writes an independent `context/message`, while `prompt-prefix` placement bakes context and the effective request into one prompt event. Drained steering bypasses `agent/prompt-submit` but applies the same placement split. Late steering retains the same record when converted to queued input, while cancellation, disposal, and terminal discard drop message and contexts together. `agent/queued` reports the frozen contexts so the observation event describes the complete retained item.
+TUI owns the snapshot/direct-message transaction without extending the generic inbox record. Outside the next-step acceptance window, it installs a one-shot outer `agent/prompt-submit` listener before `followup()`; an allowed decision receives the snapshot as `additionalContexts`, while a blocked or discarded prompt releases the listener and writes neither message. During prompt admission or an open turn, TUI calls `inject(snapshot)` then `steer(prompt)`, and AgentLoop stages both for the same safe boundary. If admission fails before that boundary, both remain staged for retry or a later admitted prompt; cancellation or disposal may discard them. The [separate-context decision](../architecture/2026-07-24-separate-context-injection-from-turn-execution.md) owns this generic delivery boundary.
 
-This preserves host driving semantics: TUI decides `send()` versus `steer()` from the agent state after preparation, so only its queued path dispatches UserPromptSubmit hooks. Reference preparation is not a new steering protocol and does not create a turn by itself.
+Reference preparation is not a new steering protocol and does not create a turn by itself. A `followup()` outside the next-step acceptance window dispatches prompt admission; steering inside the window bypasses it while retaining snapshot order through the shared outbox.
 
 ## Host adapters
 
-TUI combines session candidates with the existing `@` file provider. Each candidate displays the latest folded session title and falls back to the session id; lookup follows the editor's cancellation signal, and session id, cwd, and mention labels escape external terminal controls while the canonical URI retains the original id. TUI prepares only submissions containing structured mentions, disables duplicate submit while awaiting snapshots, restores failed input, renders the prompt envelope's display content as the user message, and renders its session-reference metadata as a compact source list instead of exposing the complete JSON in the terminal.
+TUI combines session candidates with the existing `@` file provider. Each candidate displays the latest folded session title and falls back to the session id; lookup follows the editor's cancellation signal, and session id, cwd, and mention labels escape external terminal controls while the canonical URI retains the original id. TUI prepares only submissions containing structured mentions, disables duplicate submit while awaiting snapshots, restores failed input, renders the readable direct content as the user message, and renders session-reference source metadata as a compact source list instead of exposing the complete JSON in the terminal.
 
 The [automation-only ACP transport](../simplification/2026-07-23-acp-automation-only-protocol.md) deliberately does not mount session-query or session-reference services.
 
@@ -45,15 +45,15 @@ Each of at most three references is independently capped at 65,536 UTF-8 bytes b
 - **Wait for SQLite FTS5** — rejected because snapshot correctness requires exact id reads and canonical surface folding, not content search. FTS improves discovery only.
 - **Put mention syntax in `Agent.send()`** — rejected because it would make the core protocol parse one host's presentation syntax and prevent typed non-text hosts from sharing the semantic layer.
 - **Implement references separately in each host** — rejected because projection, security warning, retention, and persistence would drift across hosts.
-- **Place a separate user-role context message beside the prompt** — rejected because two adjacent user messages weaken the prompt's deictic binding: in `@foo what does this session discuss?`, the model may resolve “this session” as the current conversation instead of the referenced snapshot.
-- **Bake the prefix host-side before `send()`** — rejected because `agent/prompt-submit` must inspect and rewrite only the direct prompt. The effective prompt and attached contexts meet only after admission in AgentLoop, which can apply an `allow.content` rewrite consistently to both combined model content and `envelope.displayContent`; earlier host assembly would expose snapshot bytes to the hook or let those two views diverge.
+- **Attach context to `SendOptions` and the inbox record** — rejected because generic delivery would own a domain transaction through admission, steering, cancellation, and observation. A domain-specific admission wrapper and the existing next-step outbox preserve the required pairing without enlarging every message.
+- **Bake the prefix host-side before `send()`** — rejected because `agent/prompt-submit` must inspect and rewrite only the direct prompt. Keeping the snapshot as a separate sourced message preserves that boundary and lets TUI hide background bytes from the direct user bubble.
 - **Replay the raw source log or restore shadowed events** — rejected because compact defines the current model surface and may intentionally retire sensitive or expensive history.
 - **Resume or fork the source** — rejected because the feature supplies read-only background for one target message, not identity or lifecycle continuity.
 - **Inject at request time by rereading the source** — rejected because the reference would become nondeterministic, cancellation races could alter its bytes, and target replay would depend on external mutable state.
 
 ## Verification
 
-Unit and integration coverage pins URI round-trips and text-boundary punctuation, explicit malformed references, title-aware candidate ranking, terminal-control escaping, projection exclusions, non-recursive prompt-envelope projection, backend-independent compact checkpoints, tag-safe framing, deduplication, self-reference, count limits, all-or-nothing reads, prompt cancellation against a non-settling storage read, independent per-source byte retention, frozen message ownership, prompt blocking, send/steer placement, title isolation, missing capability, and compact TUI replay. A keyless TUI snapshot runs the real agent loop: the source surface replaces old user/assistant history with a compact checkpoint, the target submits a mention, and the captured model request contains one user message ordered as snapshot, request delimiter, and current prompt, without either shadowed string.
+Unit and integration coverage pins URI round-trips and text-boundary punctuation, explicit malformed references, title-aware candidate ranking, terminal-control escaping, projection exclusions, non-recursive snapshot projection, backend-independent compact checkpoints, tag-safe framing, deduplication, self-reference, count limits, all-or-nothing reads, prompt cancellation against a non-settling storage read, independent per-source byte retention, prompt blocking, admission-time staging, send/steer placement, title isolation, missing capability, and compact TUI replay. A keyless TUI snapshot runs the real agent loop: the source surface replaces old user/assistant history with a compact checkpoint, the target submits a mention, and the captured model request contains a sourced snapshot message followed by the readable current prompt, without either shadowed string.
 
 ## Consequences
 

.agents/notes/implemented/feature/2026-07-21-cross-session-references.zh.md

@@ -10,7 +10,7 @@ TUI 用户需要把另一场对话中的相关工作带入一条新消息，但
 
 ## 决策
 
-`@deepseek-ai/dsh-session-reference` 是注册在 `ctx.sessionReferences` 上的单一上下文消费服务。宿主先把各自的协议规范化为 `SessionReferenceInput[]`，在入队前调用 `prepare()`，再通过通用的 `SendOptions.contexts` 边界传递返回的上下文。核心 agent 包只知道一条排队消息可以携带已冻结的 `HookContext[]`；它们既不解析会话 URI，也不读取其他日志。
+`@deepseek-ai/dsh-session-reference` 是注册在 `ctx.sessionReferences` 上的单一上下文消费服务。宿主先把各自的协议规范化为 `SessionReferenceInput[]`，并在交付前调用 `prepare()`。该服务返回分离的可读内容和一份可选的、带来源信息的 `UserMessageData` 快照；核心 agent 包既不解析会话 URI，也不读取其他日志。
 
 `dsh-session:<base64url(JSON.stringify(sessionId))>` 是与宿主无关的规范标识符。系统先执行 JSON 字符串编码，再执行 base64url 编码，因此引号、正斜杠、反斜杠、Unicode、换行符以及其他任意 JavaScript 字符串值都能无损往返，不会因分隔符产生歧义。TUI 把该 URI 渲染到 `@[label](uri)` 中；纯文本客户端可以使用同一种行内提及标记。显式 Markdown 提及标记会拒绝格式错误的 URI。裸文本只有在负载非空且形状符合 base64url 时才会成为引用，而且解码过程仍须通过规范性校验；空负载或只含标点符号的用法仍按普通讨论文本处理。
 
@@ -22,17 +22,17 @@ TUI 用户需要把另一场对话中的相关工作带入一条新消息，但
 
 投影会保留直接用户消息与 steering（中途引导）、已完成的 assistant 文本，以及携带由 `dsh-compact` 导出的规范来源标记的检查点用户消息。该标记属于压缩功能契约的一部分，而非某个后端包名称。当源提示词已包含合并写入的前缀上下文时，投影只读取其模型不可见的显示内容，因此后续引用该目标不会递归传播先前的快照。投影会排除压缩前已被遮蔽的节点、工具及其结果、推理（reasoning）、注入的上下文、其他插件用户消息、仅用于日志的记录，以及尚未完成的 assistant 分片。因此，重复压缩只会暴露当前表层仍保留的最新折叠检查点谱系及其尾部消息；系统不提供 raw/current 开关，也不恢复被遮蔽的内容。
 
-系统把一个聚合上下文序列化为 JSON，并置于固定的不可信背景警告之后。该警告要求模型不要遵循被引用会话中的指令、权限声明或工具请求，除非当前用户再次提出这些内容。标签安全序列化会把数据中的每个 `<` 无损转义为 JSON `\u003c`；因此源字符串无法拼出外围类似 XML 的标签。`## My request:` 文本只是路由提示，不是信任边界：被引用数据可以在 JSON 字符串中包含这些词，但无法伪造闭合的 `</referenced-sessions>` 标签，也无法逃逸数据区域。同一个序列化器会独立核算每个源的字节数。该上下文声明 `prompt-prefix` 放置方式，因此 AgentLoop 会持久化一条 `user/message` 或 `steering/message`，其中包含快照、`## My request:` 分隔符和最终生效的直接提示词。其模型不可见封套保留直接显示内容以及来源与保留元数据。因此，目标回放无需新增事件类型或单独的用户角色上下文消息，也能满足「模型可见／日志可重建」不变量。
+系统把一个聚合上下文序列化为 JSON，并置于固定的不可信背景警告之后。该警告要求模型不要遵循被引用会话中的指令、权限声明或工具请求，除非当前用户再次提出这些内容。标签安全序列化会把数据中的每个 `<` 无损转义为 JSON `\u003c`；因此源字符串无法拼出外围类似 XML 的标签，也无法逃逸数据区域。同一个序列化器会独立核算每个源的字节数。AgentLoop 会把快照持久化为一条带来源信息的 `user/message`，紧接在直接 `user/message` 或 `steering/message` 之前。因此，目标回放无需新增事件类型、放置模式或提示词封套，也能满足「模型可见／日志可重建」不变量。
 
 ## 消息所有权
 
-`send()` 与 `steer()` 会把内容、解析后的来源和上下文一起快照为一条深度冻结、无损 JSON 的收件箱记录。合成的 `inject()` 接受来源和模型不可见的元数据，但不接受附加上下文，因为上下文属于收件箱消息。普通消息被认领后，其附带的上下文会作为 `agent/prompt-submit` 的默认附加上下文公开；提示词被阻止时，系统既不写入用户消息，也不写入上下文。waterfall（瀑布式事件）返回的 allow 结果具有最终权威性，因此监听器包装 `next()` 时会保留下游内容与上下文，除非它有意替换这些值。消息被接纳后，未指定放置方式或指定为 `separate` 时会写入独立的 `context/message`；指定为 `prompt-prefix` 时则会把上下文与最终生效的请求合并写入同一个提示词事件。排空 steering 消息时会绕过 `agent/prompt-submit`，但采用相同的放置方式分流。延迟到达的 steering 转换为排队输入时保留同一条记录；取消、dispose（资源释放）和到达终止态后的丢弃则会同时丢弃消息与上下文。`agent/queued` 会报告已冻结的上下文，使观察事件能够描述完整的保留项。
+TUI 负责快照／直接消息事务，不扩展通用收件箱记录。在 next-step 接受窗口之外，它会在调用 `followup()` 前安装一次性的外层 `agent/prompt-submit` 监听器；获准决策会把快照作为 `additionalContexts` 接收，而被阻止或丢弃的提示词会释放监听器，并且不写入任何消息。提示词准入期间或轮次打开时，TUI 会依次调用 `inject(snapshot)` 和 `steer(prompt)`，AgentLoop 则将两者暂存到同一个安全边界。如果准入在抵达该边界前失败，两者都会保留暂存状态，供重试或后续获准提示词使用；取消或资源释放可能丢弃它们。这一通用交付边界由[上下文分离决策](../architecture/2026-07-24-separate-context-injection-from-turn-execution.md)规定。
 
-这保留了宿主的驱动语义：TUI 在准备完成后根据 agent 状态决定调用 `send()` 还是 `steer()`，因此只有它的排队路径才会分派 UserPromptSubmit 钩子。引用准备过程不是新的 steering 协议，本身也不会创建轮次。
+引用准备过程不是新的 steering 协议，本身也不会创建轮次。在 next-step 接受窗口之外调用 `followup()` 会分派提示词准入；窗口内的 steering 会绕过它，同时通过共享 outbox 保持快照顺序。
 
 ## 宿主适配器
 
-TUI 把会话候选与现有 `@` 文件提供方组合在一起。每个候选项显示最新折叠后的会话标题，没有标题时回退到 session id。候选查询遵循编辑器的取消信号；session id、cwd 和提及标签中的外部终端控制字符会被转义，但规范 URI 仍保留原始 id。TUI 只准备包含结构化提及标记的提交；等待快照时禁用重复提交；失败时恢复输入；它把提示词封套的显示内容渲染为用户消息，并把其中的会话引用元数据渲染为精简的来源列表，不在终端中暴露完整 JSON。
+TUI 把会话候选与现有 `@` 文件提供方组合在一起。每个候选项显示最新折叠后的会话标题，没有标题时回退到 session id。候选查询遵循编辑器的取消信号；session id、cwd 和提及标签中的外部终端控制字符会被转义，但规范 URI 仍保留原始 id。TUI 只准备包含结构化提及标记的提交；等待快照时禁用重复提交；失败时恢复输入；它把可读的直接内容渲染为用户消息，并把会话引用来源元数据渲染为精简的来源列表，不在终端中暴露完整 JSON。
 
 [仅面向自动化的 ACP（Agent Client Protocol）传输层](../simplification/2026-07-23-acp-automation-only-protocol.md)有意不挂载会话查询或会话引用服务。
 
@@ -45,15 +45,15 @@ TUI 把会话候选与现有 `@` 文件提供方组合在一起。每个候选
 - **等待 SQLite FTS5**：不予采纳，因为快照正确性依赖按准确 id 读取和规范表层折叠，而不是内容搜索。FTS 只改进候选发现。
 - **把提及标记语法放入 `Agent.send()`**：不予采纳，因为这会迫使核心协议解析某个宿主的展示语法，并阻止带类型的非文本宿主复用同一语义层。
 - **在每个宿主中分别实现引用**：不予采纳，因为投影、安全警告、保留策略和持久化会在不同宿主之间逐渐偏离。
-- **在提示词旁放置单独的用户角色上下文消息**：不予采纳，因为相邻的两条用户消息会削弱提示词的指示语绑定：在 `@foo what does this session discuss?` 中，模型可能把「this session」解析为当前对话，而不是被引用的快照。
-- **在调用 `send()` 前由宿主合并前缀**：不予采纳，因为 `agent/prompt-submit` 必须只检查和改写直接提示词。最终生效的提示词与附加上下文只有在 AgentLoop 接纳后才汇合；此时 AgentLoop 可以把 `allow.content` 改写一致应用于合并后的模型内容和 `envelope.displayContent`。若由宿主更早组装，就会向该钩子暴露快照字节，或使这两个视图发生偏离。
+- **把上下文附加到 `SendOptions` 和收件箱记录**：不予采纳，因为通用投递将不得不负责贯穿准入、steering、取消和观察的领域事务。领域专用的准入包装层和现有 next-step outbox 可以保持所需配对，而无需扩大每条消息。
+- **在调用 `send()` 前由宿主合并前缀**：不予采纳，因为 `agent/prompt-submit` 必须只检查和改写直接提示词。将快照保留为独立的带来源消息，可以维持该边界，并让 TUI 从直接用户气泡中隐藏背景字节。
 - **回放原始源日志或恢复被遮蔽的事件**：不予采纳，因为压缩定义了当前模型表层，并且可能有意淘汰敏感或开销高昂的历史内容。
 - **恢复或 fork 源会话**：不予采纳，因为本功能只为一条目标消息提供只读背景，不提供身份或生命周期连续性。
 - **在请求时重新读取源会话并注入**：不予采纳，因为这会让引用变得不确定，取消竞态可能改变其字节内容，目标回放也会依赖可变的外部状态。
 
 ## 验证
 
-单元与集成测试覆盖 URI 无损往返与文本边界标点、显式格式错误的引用、会考虑标题的候选排序、终端控制字符转义、投影排除规则、提示词封套的非递归投影、与后端无关的压缩检查点、标签安全封套、去重、自引用、数量限制、读取的全有或全无、存储读取不结束时取消提示词、逐源独立字节保留、冻结的消息所有权、提示词阻止、send／steer 放置方式、标题隔离、功能缺失和精简的 TUI 回放。无密钥 TUI 快照会运行真实的 agent loop（智能体循环）：源表层用一个压缩检查点替换旧的用户／assistant 历史，目标会话提交一个提及标记，捕获到的模型请求只包含一条用户消息，其中依次为快照、请求分隔符和当前提示词，并且不包含任一被遮蔽的字符串。
+单元与集成测试覆盖 URI 无损往返与文本边界标点、显式格式错误的引用、会考虑标题的候选排序、终端控制字符转义、投影排除规则、快照的非递归投影、与后端无关的压缩检查点、标签安全封套、去重、自引用、数量限制、读取的全有或全无、存储读取不结束时取消提示词、逐源独立字节保留、提示词阻止、准入期间的暂存、send／steer 放置方式、标题隔离、功能缺失和精简的 TUI 回放。无密钥 TUI 快照会运行真实的 agent loop（智能体循环）：源表层用一个压缩检查点替换旧的用户／assistant 历史，目标会话提交一个提及标记，捕获到的模型请求包含一条带来源的快照消息，后面跟随可读的当前提示词，并且不包含任一被遮蔽的字符串。
 
 ## 后果