feat(subagent): make final reports the continuable return contract

A continuable child could finish without giving its parent a usable
result: the report tool was described as optional and its default
delivery stayed quiet. Install the child-scoped report obligation (tool
description plus the tool:report prompt section), default reportDelivery
to wakeup, bind shipped subagent_fork delegations to one-shot so fork
keeps its prefix reuse, and extend the ACP snapshot harness to pin child
system prompts alongside child tool schemas.

.agents/notes/implemented/architecture/2026-08-10-fork-children-stay-one-shot.i18n.yaml

@@ -0,0 +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 .agents/notes/implemented/architecture/2026-08-10-fork-children-stay-one-shot.md
+2026-08-10-fork-children-stay-one-shot.md: 030bed3c1b516a54afd5f97b00000ed7ceaf64d8
+2026-08-10-fork-children-stay-one-shot.zh.md: 4b033a70c3674315c491e85be67a1d357aeac51b

.agents/notes/implemented/architecture/2026-08-10-fork-children-stay-one-shot.md

@@ -0,0 +1,49 @@
+# Agent Note: Forked children stay one-shot
+
+Status: implemented
+
+English | [中文](2026-08-10-fork-children-stay-one-shot.zh.md)
+
+## Problem
+
+Fork's only difference from spawn is that the child Session is seeded with the parent's completed-turn prefix ([subagent-fork](../../../../packages/subagent/subagent-fork/README.md)). That seed costs real tokens — the inherited history is re-sent in every child request — and its one concrete payoff is provider-side prefix reuse: under the same provider and model, a child request whose leading bytes are identical to the parent's re-prefills none of the shared span. Anything a child scope adds *ahead* of the inherited history spends that payoff, because reuse stops at the first differing byte.
+
+The child-scoped `report` return channel is now the largest such addition, and since [the report obligation](../feature/2026-08-06-continuable-child-report-obligation.md) it is two deltas rather than one: the `report` tool schema and the `tool:report` system-prompt section. Both live in the request head — the system block and the tool block precede every message — so a continuable forked child invalidates reuse before the first inherited turn and re-prefills the whole transcript it was forked to reuse. That composition pays fork's duplication cost and collects none of its benefit, while the parent still holds a reusable prefix the child could have shared.
+
+## Decision
+
+Every shipped composition binds the fork delegation tool to `backgroundMode: one-shot`: [the base bundle](../../../../packages/bundle/base/cordis.patch.yml), [the ACP example](../../../../examples/acp-agent/cordis.yml), and [the headless example](../../../../examples/headless-agent/cordis.yml). The base bundle leaves `run_in_background` available, because it mounts a task service; the two examples set `enableRunInBackground: false`, because they mount none and a one-shot background start would otherwise fail at call time on a missing `tasks` service.
+
+One-shot children — foreground and background alike — are created through `SubagentService.start()`, which never enters the continuable activation-setup registry, so neither `report` nor its prompt section is installed. A forked one-shot child's system prompt and tool schemas therefore equal its parent's, apart from the `persona` and `toolFilter` deltas a deployment opts into per delegation tool.
+
+`spawn` keeps `backgroundMode: continuable`. Continuable children and the report obligation ship unchanged for the provider whose child starts with no inherited prefix to protect, so this decision costs the report channel nothing.
+
+### The restriction is composition, not code
+
+`ForkProvider.prepareContinuable` stays implemented and `ctx.subagents.startContinuable()` still accepts `fork`; only the shipped `cordis.yml` rows changed. `tool-subagent` knows both the provider's `inheritsParentContext` and its own `backgroundMode` at mount, so a load-time rejection of the pair was available and is deliberately not added: the pair is not wrong in general. It is wrong only while a child-scope delta precedes inherited history, and the package that creates that delta — [`dsh-tool-subagent-report`](../../../../packages/subagent/tool-subagent-report/README.md) — is separately installable and, by its own design, invisible to `tool-subagent`. A deployment that omits the report package can run continuable forked children with the prefix intact. Encoding one roster's consequence as a delegation-tool invariant would make the tool assert something it cannot observe.
+
+The reintroduction condition is recorded as a `TODO(fork-continuable-prefix-reuse)` marker on `prepareContinuable` itself, the one method the shipped compositions do not call, and tracked as issue #2124: continuable fork reopens when a child's system prompt and tool schemas can match its parent's byte for byte.
+
+## Alternatives considered
+
+**Reject `inheritsParentContext` + `continuable` at mount.** A loud load-time failure would prevent silent reintroduction, which is what the configuration change cannot do. Rejected because the delegation tool cannot see the report package and the combination is legitimate without it; the invariant would be false for a deployment that never installs a child-scope delta, and `tool-subagent` would be asserting a fact owned by the roster.
+
+**Stop mounting the fork provider at all.** This was the broader form of the restriction. Rejected because foreground fork *is* the prefix-reusing case and is untouched by the report channel, so a full ban gives up the capability without buying anything the one-shot binding does not already buy — and would leave no shipped composition exercising session seeding.
+
+**Ship continuable forked children and accept the loss.** Rejected because the loss is total rather than marginal: reuse breaks ahead of the inherited history, so the child pays full prefill on a transcript it duplicated for the sole purpose of not paying it. A deployment that wants a long-lived child with no inherited context already has `spawn`.
+
+**Make `report` visible to every Agent.** A global registration would restore byte-identical prefixes by giving parent and child the same schema and section. Rejected because roots, one-shot children, remote children, and agentless callers would advertise a tool with no derivable recipient, and execution-time rejection would make schema visibility disagree with authority — the scope-local decision the [report tool Agent Note](../feature/2026-07-30-continuable-subagent-report-tool.md) already settled.
+
+**Install the child-scope deltas after the inherited history.** Rejected as unrepresentable: the system prompt and the tool schemas are request-head structures in every provider's wire format, so no ordering within them can place a child-only addition behind the message list.
+
+## Consequences
+
+- No shipped composition creates a continuable forked child; `subagent_fork` returns a result to its caller's turn, and `send_message` addresses only spawned children.
+- A forked child's request prefix stays byte-identical to its parent's unless the deployment configures `persona` or `toolFilter` on the fork delegation tool, so the token cost of seeding buys provider-side reuse again.
+- The fork provider's continuable path has no production caller and no assembled-composition coverage. It keeps its package-level tests, and the seam still accepts it, so a bundle or `--patch` overlay can reintroduce it with no code change and no warning.
+- `subagent_fork`'s model-visible schema changes: the continuable background wording is replaced by the one-shot task wording in the base bundle, and disappears entirely from the two examples. The affected keyless snapshot tool-schema sidecars are re-recorded in the same change.
+- The report obligation's reach narrows to spawned children in shipped deployments. Its default `wakeup` scheduling, authority model, and coverage are unchanged.
+
+### Accepted risks
+
+The constraint lives in three configuration files and a code comment, not in a gate. A future bundle row or profile patch can set `backgroundMode: continuable` on a fork tool and silently reintroduce the prefix loss; nothing fails loud. That is the accepted cost of not encoding one roster's consequence into `tool-subagent`.

.agents/notes/implemented/architecture/2026-08-10-fork-children-stay-one-shot.zh.md

@@ -0,0 +1,49 @@
+# Agent Note: fork 出的 child 保持 one-shot
+
+Status: implemented
+
+[English](2026-08-10-fork-children-stay-one-shot.md) | 中文
+
+## 问题
+
+fork 与 spawn 的唯一区别是 child 的 Session 会以 parent 已完成轮次的前缀作为初始内容（见 [subagent-fork](../../../../packages/subagent/subagent-fork/README.md)）。这份初始内容有实打实的 token 成本——继承的历史会在 child 的每次请求中重新发送——而它唯一确定的回报是提供方侧的前缀复用：在提供方与模型相同的前提下，起始字节与 parent 逐字节相同的 child 请求，无需为这段共享区间重新预填充。任何由 child 作用域添加在继承历史*之前*的内容都会消耗掉这份回报，因为复用在第一个不同字节处即告停止。
+
+作用域局部的 `report` 返回通道现在是此类添加中最大的一项，而自[report 义务](../feature/2026-08-06-continuable-child-report-obligation.md)起它是两项而非一项增量：`report` 工具 schema，以及 `tool:report` 系统提示词 section。两者都位于请求头部——系统块与工具块先于所有消息——因此一个可继续的 fork child 会在第一条继承轮次之前就使复用失效，并重新预填充它当初 fork 就是为了复用的整份 transcript（文本记录）。这种组合付出了 fork 的复制成本却收不到它的收益，而 parent 手上仍握着一份 child 本可共享的可复用前缀。
+
+## 决策
+
+所有随附组合都把 fork 委派工具绑定为 `backgroundMode: one-shot`：[base 组合包](../../../../packages/bundle/base/cordis.patch.yml)、[ACP 示例](../../../../examples/acp-agent/cordis.yml)与[headless 示例](../../../../examples/headless-agent/cordis.yml)。base 组合包保留 `run_in_background`，因为它挂载了 task 服务；两个示例设置 `enableRunInBackground: false`，因为它们都不挂载 task 服务，否则一次 one-shot 后台启动会在调用时因缺少 `tasks` 服务而失败。
+
+one-shot child——前台与后台皆然——经由 `SubagentService.start()` 创建，该路径从不进入可继续的 activation setup 注册表，因此 `report` 与它的提示词 section 都不会被安装。于是一个 fork 出的 one-shot child 的系统提示词与工具 schema 与其 parent 相同，只差部署逐个委派工具主动选择的 `persona` 与 `toolFilter` 增量。
+
+`spawn` 保持 `backgroundMode: continuable`。对于 child 起步时本就没有继承前缀需要保护的那个提供方，可继续 child 与 report 义务随附行为不变，因此本决策没有让 report 通道付出任何代价。
+
+### 该限制在于组合，不在于代码
+
+`ForkProvider.prepareContinuable` 仍然实现完好，`ctx.subagents.startContinuable()` 也仍接受 `fork`；改动的只有随附的 `cordis.yml` 行。`tool-subagent` 在挂载时同时知道提供方的 `inheritsParentContext` 与自身的 `backgroundMode`，因此一个加载期拒绝该组合的检查是可行的，而这里刻意不加：该组合并非普遍错误。它只在某个 child 作用域增量位于继承历史之前时才是错的，而产生该增量的包——[`dsh-tool-subagent-report`](../../../../packages/subagent/tool-subagent-report/README.md)——是独立安装的，并且按其自身设计对 `tool-subagent` 不可见。一个不安装 report 包的部署可以在前缀完好的前提下运行可继续的 fork child。把某一份插件清单的后果写成委派工具的不变量，会让该工具断言它无法观察到的事实。
+
+重新开放的条件记录为 `prepareContinuable` 方法上的 `TODO(fork-continuable-prefix-reuse)` 标记——随附组合不调用这个方法——并由 issue #2124 跟踪：当 child 的系统提示词与工具 schema 能与其 parent 逐字节一致时，可继续 fork 即可重新开放。
+
+## 备选方案
+
+**在挂载时拒绝 `inheritsParentContext` 与 `continuable` 的组合。** 一次响亮的加载期失败可以阻止悄然的重新引入，而配置改动做不到这一点。否决的原因是委派工具看不到 report 包，且在没有它时该组合是合法的；对于从不安装任何 child 作用域增量的部署，这个不变量是假的，而 `tool-subagent` 会去断言一件由插件清单拥有的事实。
+
+**干脆不挂载 fork 提供方。** 这是该限制更彻底的形式。否决的原因是前台 fork *正是*复用前缀的那种情形，且不受 report 通道影响，因此全面禁用会在不换来任何 one-shot 绑定尚未换来的东西的同时放弃该能力——并且随附组合将没有任何一个演练 session 初始内容。
+
+**照常随附可继续的 fork child 并接受这份损失。** 否决的原因是这份损失是全额而非边际的：复用在继承历史之前就已中断，于是 child 为一份自己复制过来、目的恰恰是不必付费的 transcript 付了全额预填充。想要一个没有继承上下文的长期 child 的部署，本来就有 `spawn`。
+
+**让 `report` 对每个 Agent 可见。** 全局注册会通过让 parent 与 child 拥有相同的 schema 与 section 来恢复逐字节相同的前缀。否决的原因是根 agent、one-shot child、远端 child 与无 agent 调用方都会宣告一件推导不出收件方的工具，而执行期拒绝会让 schema 可见性与权限彼此矛盾——这正是[report 工具 Agent Note](../feature/2026-07-30-continuable-subagent-report-tool.md)已经定下的作用域局部决策。
+
+**把 child 作用域增量安装到继承历史之后。** 否决的原因是它无法表达：在每个提供方的协议格式中，系统提示词与工具 schema 都是请求头部结构，因此它们内部的任何排序都无法把仅属于 child 的添加放到消息列表之后。
+
+## 后果
+
+- 没有任何随附组合会创建可继续的 fork child；`subagent_fork` 把结果返回给调用方的轮次，而 `send_message` 只寻址 spawn 出的 child。
+- 除非部署在 fork 委派工具上配置了 `persona` 或 `toolFilter`，fork child 的请求前缀与其 parent 逐字节相同，因此初始内容的 token 成本重新换来了提供方侧的复用。
+- fork 提供方的可继续路径没有生产调用方，也没有整体组装层面的覆盖。它保留自己的包内测试，seam 也仍然接受它，因此某个组合包或 `--patch` 覆盖层可以无需改动代码、也不会有任何警告地把它重新引入。
+- `subagent_fork` 面向模型的 schema 发生变化：base 组合包中可继续的后台措辞被 one-shot 的 task 措辞取代，在两个示例中则完全消失。受影响的无密钥快照工具 schema 伴随文件在同一次改动中重新记录。
+- 在随附部署中，report 义务的覆盖范围收窄到 spawn 出的 child。它的 `wakeup` 默认调度、权限模型与覆盖均保持不变。
+
+### 已接受的风险
+
+该限制存在于三个配置文件与一处代码注释中，而不在门禁里。未来某个组合包行或 profile 补丁可以在 fork 工具上设置 `backgroundMode: continuable`，从而悄然重新引入前缀损失；没有任何东西会失败得很响亮。这就是不把某一份插件清单的后果写入 `tool-subagent` 所接受的代价。

.agents/notes/implemented/feature/2026-07-30-continuable-subagent-report-tool.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 .agents/notes/implemented/feature/2026-07-30-continuable-subagent-report-tool.md
-2026-07-30-continuable-subagent-report-tool.md: 6a607f1da48fdfde36b2d9351f131dd3ef67ba7f
-2026-07-30-continuable-subagent-report-tool.zh.md: b4d65fc71695e9fca46f4e2c69c9749745de260a
+2026-07-30-continuable-subagent-report-tool.md: d4681d0ea30335a5537525927ecad615e6edd8b8
+2026-07-30-continuable-subagent-report-tool.zh.md: 731225d2a5b788997704fafe9331901ca9b84393

.agents/notes/implemented/feature/2026-07-30-continuable-subagent-report-tool.md

@@ -12,7 +12,7 @@ Treating every final assistant message as an implicit result would conflate turn
 
 ## Decision
 
-Add the independently installed `@deepseek-ai/dsh-tool-subagent-report` package. It contributes an ordinary model-facing `report` tool to each continuable in-process child Activation. A child may call it zero or multiple times in a turn. Success neither concludes the turn, settles the Activation, nor prevents later parent follow-ups, and finishing a turn never reports automatically.
+Add the independently installed `@deepseek-ai/dsh-tool-subagent-report` package. It contributes an ordinary model-facing `report` tool to each continuable in-process child Activation. The mechanism accepts zero or multiple calls in a turn; the child is separately instructed to call it once before finishing ([the report obligation](2026-08-06-continuable-child-report-obligation.md)). Success neither concludes the turn, settles the Activation, nor prevents later parent follow-ups, and finishing a turn never reports automatically.
 
 The feature is a collaboration control, not a result-bearing execution wrapper. It adds no Task, `SubagentRun`, result promise, Activation state, delivery queue, or replay path.
 
@@ -22,7 +22,7 @@ The feature is a collaboration control, not a result-bearing execution wrapper.
 
 `messageId` is the stable `MessageId` of the user-role message accepted by the parent. It is not an `InboxItemId`: quiet delivery creates no inbox occurrence, while waking delivery creates one occurrence for the same stable message. It is also not a read receipt, parent-log acknowledgement, turn-completion receipt, or persistence flush.
 
-The description states that reporting is explicit, repeatable, direct-parent-only, and non-terminal. It warns that a failed tool result may still follow an accepted send because a later `tools/post-execute` failure can replace the result. Without an idempotency key, stronger wording would encourage duplicate retries after ambiguous failure.
+The description states that reporting is required before finishing, repeatable, direct-parent-only, and non-terminal. It warns that a failed tool result may still follow an accepted send because a later `tools/post-execute` failure can replace the result. Without an idempotency key, stronger wording would encourage duplicate retries after ambiguous failure.
 
 The tool uses generic rendering with no locations. Its acknowledgement includes `messageId`. Scope-local registration keeps presentation and execution aligned: roots, one-shot children, remote providers, sibling scopes, and agentless execution neither see nor execute `report`. It installs after the child's global `toolFilter`, so a delegation allow-list cannot accidentally remove the structural return channel; deployments that require no return channel omit the package.
 
@@ -36,7 +36,7 @@ Nested reporting crosses exactly one edge. A grandchild reports to its direct ch
 
 ### Delivery policy
 
-The package validates `reportDelivery: 'quiet' | 'wakeup'`; the default is `quiet`.
+The package validates `reportDelivery: 'quiet' | 'wakeup'`; the default is `wakeup` ([why the default reversed](2026-08-06-continuable-child-report-obligation.md)).
 
 Quiet delivery calls `parent.inject()`. It adds model-visible context without starting a parent model request: an idle parent appends before the call returns, while an admitting or running parent stages the report for the next safe log position. It creates no inbox occurrence and therefore no synthetic continuation-manager acceptance record.
 
@@ -56,13 +56,13 @@ The subagent seam adds `registerContinuableSetup(contribution): () => void`, bac
 
 The registry owns registration, per-child installation records, setup rollback, child-scope cleanup, and immediate revocation. Applying a batch returns the Agent setup commit that revalidates provisioning after every setup await and immediately before Agent publication. A throwing or concurrently revoked contribution therefore rejects before either Agent or Session publication and rolls back the batch. New registrations affect a resident child only on its next Activation; removing a registration first closes it to new setup and then revokes every provisioning or resident installation immediately. Registration disposal and child-context disposal are idempotent and attempt every release before aggregating failures.
 
-This seam keeps the continuation manager unaware of tool names. The report package installs only `report`; `@deepseek-ai/dsh-tool-subagent-control` independently installs parent-side `send_message` and `list_agents`. A deployment can install either direction, both, or neither. Providers remain data-only, durable descriptors do not snapshot report availability or delivery mode, and cold resume uses the deployment's current contributions and policy.
+This seam keeps the continuation manager unaware of tool names. The report package installs only `report` and its child-scoped guidance section; `@deepseek-ai/dsh-tool-subagent-control` independently installs parent-side `send_message` and `list_agents`. A deployment can install either direction, both, or neither. Providers remain data-only, durable descriptors do not snapshot report availability or delivery mode, and cold resume uses the deployment's current contributions and policy.
 
 ### Snapshot coverage
 
-The ACP snapshot harness adds `waitForSubagentTurnEnd`, selecting the Nth harvested child by the same order as `session.N.jsonl`. It waits for a closed child turn containing a request header so a continuable child's earlier descriptor-seed turn cannot satisfy the boundary. This lets the assembled quiet-mode scenario wait for the child-side report without inventing a parent-visible signal.
+The ACP snapshot harness adds `waitForSubagentTurnEnd`, selecting the Nth harvested child by the same order as `session.N.jsonl`. It waits for a closed child turn containing a request header so a continuable child's earlier descriptor-seed turn cannot satisfy the boundary. This lets the assembled scenario wait for the child-side report without inventing a parent-visible signal.
 
-The authored snapshot starts a continuable child, executes the real scope-local `report` tool, confirms that the idle parent is not woken, and then submits a later parent prompt that consumes the framed report. It declares child schema pin `1`, so the otherwise non-global `report` schema is checked against `tool-schemas.1.expected.json` while the root keeps the default schema pin. The generated tool catalog separately mints a child scope to include the same scope-local schema.
+The authored snapshot starts a continuable child, executes the real scope-local `report` tool, observes the one ordinary parent turn the default waking delivery creates, and then submits a later parent prompt that consumes the framed report. It declares child pins `1`, so the otherwise non-global `report` schema and the child's own prompt are checked against `tool-schemas.1.expected.json` and `system-prompt.1.expected.md` while the root keeps the class pins. The generated tool catalog separately mints a child scope to include the same scope-local schema.
 
 ## Alternatives considered
 
@@ -72,7 +72,7 @@ Automatic delivery cannot represent zero reports, progress reports, or several s
 
 ### Always wake the parent
 
-Waking on every report creates unsolicited turns and can cascade through nested subagents. Quiet delivery matches background coordination better as the default, while deployments that require immediate action can select wakeup.
+Waking on every report creates unsolicited turns and can cascade through nested subagents. Quiet delivery was chosen as the default on the assumption that the parent had another reason to read its context. [The report obligation](2026-08-06-continuable-child-report-obligation.md) supersedes that choice: a parked background coordinator has no such reason, so waking is the default and this paragraph now records why `quiet` still exists.
 
 ### Let the child choose the delivery mode
 
@@ -103,16 +103,16 @@ A post-creation revocation check can reject the Activation only after the Agent
 - A continuable in-process child exposes exactly one scope-local `report` schema only while the report package's contribution is installed; unrelated Agents never expose it.
 - The tool returns the parent message's stable `MessageId`. Quiet delivery has no `InboxItemId`; waking delivery has a separate inbox occurrence.
 - Only the exact resident child may report, and only to the exact live direct parent derived from durable lineage. The service has no recipient parameter or offline fallback.
-- Quiet delivery is the validated default and never starts a parent request. Wakeup creates exactly one later FIFO turn and never steers an open turn.
+- Waking delivery is the validated default: it creates exactly one later FIFO turn and never steers an open turn. Quiet delivery never starts a parent request.
 - Child cancellation or disposal after parent acceptance does not retract the report. Before acceptance, child disposal, drain, parent loss, or caller cancellation rejects the operation.
 - Fresh and resumed Activations compose current setup contributions before publication. Grants wait for the next Activation; revocation is immediate for resident children.
 - Unit coverage pins visibility, allow-list behavior, both delivery modes, stable message and sender identities, nested routing, invalid senders, absent parents, cancellation, drain, revocation races, and the absence of Tasks or implicit final reporting.
-- The keyless assembled snapshot proves the real child tool, quiet non-wakeup behavior, durable parent framing, and later parent consumption.
+- The keyless assembled snapshot proves the real child tool, the one waking parent turn, durable parent framing, and later parent consumption.
 
 ### Accepted risks
 
 The acceptance boundary is weaker than durable end-to-end delivery. A crash can leave the result ambiguous, and retries may duplicate reports.
 
-Wakeup mode can amplify model work when nested children report frequently. Deployment ownership and a quiet default limit but do not remove that risk.
+Waking delivery can amplify model work when nested children report frequently. Deployment ownership through `reportDelivery` bounds but does not remove that risk.
 
 Registry presence is the parent liveness signal. A host-owned parent whose `AgentHandle.dispose()` has started but has not yet unwound its scope can still accept and append a report that it will not act on in this process. Closing that gap requires an Agent-level disposal-start signal rather than subagent-layer inference.

.agents/notes/implemented/feature/2026-07-30-continuable-subagent-report-tool.zh.md

@@ -12,7 +12,7 @@ Status: implemented
 
 ## 决策
 
-新增可独立安装的 `@deepseek-ai/dsh-tool-subagent-report` 包。它会向每个可继续进程内 child Activation 贡献一个普通的面向模型 `report` 工具。child 在一个轮次中可调用零次或多次。调用成功既不会结束该轮次或结算 Activation，也不会阻止 parent 之后继续 follow-up；完成轮次也绝不会自动报告。
+新增可独立安装的 `@deepseek-ai/dsh-tool-subagent-report` 包。它会向每个可继续进程内 child Activation 贡献一个普通的面向模型 `report` 工具。机制本身接受一个轮次中调用零次或多次；child 会另行被要求在结束前调用一次（见[报告义务](2026-08-06-continuable-child-report-obligation.md)）。调用成功既不会结束该轮次或结算 Activation，也不会阻止 parent 之后继续 follow-up；完成轮次也绝不会自动报告。
 
 该功能是协作控制，不是承载结果的执行包装层。它不新增 Task、`SubagentRun`、结果 promise、Activation 状态、投递队列或回放路径。
 
@@ -22,7 +22,7 @@ Status: implemented
 
 `messageId` 是 parent 接受的用户角色消息所对应的稳定 `MessageId`。它不是 `InboxItemId`：静默投递不创建 inbox 条目实例，唤醒投递则会为同一条稳定消息创建一个条目实例。它也不是已读回执、parent 日志确认、轮次完成回执或持久化 flush。
 
-工具描述会明确报告操作是显式、可重复、仅限直接 parent 且不会结束轮次的。它还会警告：发送被接受后，后续 `tools/post-execute` 失败可能替换工具结果，因此工具结果失败时内容仍可能已经送达。没有幂等键时，更强的表述会诱导调用方在结果不明确的失败后重复重试。
+工具描述会明确报告操作在结束前必须执行、可重复、仅限直接 parent 且不会结束轮次。它还会警告：发送被接受后，后续 `tools/post-execute` 失败可能替换工具结果，因此工具结果失败时内容仍可能已经送达。没有幂等键时，更强的表述会诱导调用方在结果不明确的失败后重复重试。
 
 该工具使用不带 location 的通用渲染，其确认中包含 `messageId`。作用域局部注册使呈现与执行保持一致：root、one-shot child、远程提供方、同级作用域和无 agent（智能体）执行既不能看到，也不能执行 `report`。它会在 child 的全局 `toolFilter` 之后安装，因此委派 allow-list 不会意外移除这条结构性返回通道；不需要返回通道的部署不安装该包。
 
@@ -36,7 +36,7 @@ root、one-shot child、伪造对象、陈旧 Agent 和同 id 替换对象都以
 
 ### 投递策略
 
-该包会校验 `reportDelivery: 'quiet' | 'wakeup'`，默认值为 `quiet`。
+该包会校验 `reportDelivery: 'quiet' | 'wakeup'`，默认值为 `wakeup`（见[默认值反转的理由](2026-08-06-continuable-child-report-obligation.md)）。
 
 静默投递调用 `parent.inject()`。它会添加模型可见上下文，但不启动 parent 模型请求：若 parent 空闲，则在调用返回前追加消息；若 parent 正在准入或运行，则暂存报告，留到下一个安全日志位置。该模式不创建 inbox 条目实例，因此也不会产生虚构的继续执行管理器接受记录。
 
@@ -56,13 +56,13 @@ subagent seam 新增 `registerContinuableSetup(contribution): () => void`，由
 
 注册表负责注册、每个 child 的安装记录、设置回滚、child 作用域清理和立即撤销。应用一个批次会返回 Agent setup 提交对象，用于在所有 setup 的 await 均结算后、紧邻 Agent 发布前重新校验配置状态。因此，某项贡献抛出异常或被并发撤销时，会在 Agent 与会话发布前拒绝操作并回滚该批次。新注册项只会在驻留 child 的下一个 Activation 生效；移除注册项时，会先将它对新设置关闭，再立即撤销为正在配置或驻留的每个 child 安装的实例。注册 dispose（资源释放）与 child 上下文 dispose 都是幂等的，两者都会先尝试每项释放，再聚合失败。
 
-该 seam 使继续执行管理器无需知道工具名。report 包只安装 `report`；`@deepseek-ai/dsh-tool-subagent-control` 则独立安装 parent 侧的 `send_message` 和 `list_agents`。部署时可安装任一方向、同时安装两者或两者均不安装。提供方仍只负责数据，持久化描述符不会对 report 可用性或投递模式建立快照，冷恢复则使用部署当前的贡献与策略。
+该 seam 使继续执行管理器无需知道工具名。report 包只安装 `report` 及其 child 作用域指引 section；`@deepseek-ai/dsh-tool-subagent-control` 则独立安装 parent 侧的 `send_message` 和 `list_agents`。部署时可安装任一方向、同时安装两者或两者均不安装。提供方仍只负责数据，持久化描述符不会对 report 可用性或投递模式建立快照，冷恢复则使用部署当前的贡献与策略。
 
 ### 快照覆盖
 
-ACP（Agent Client Protocol）快照 harness 新增 `waitForSubagentTurnEnd`，按与 `session.N.jsonl` 相同的顺序选择第 N 个已收集 child。它会等待一个包含请求 header 的已闭合 child 轮次，以防可继续 child 早期播种描述符的轮次错误满足该边界。这样，整体组装的静默模式场景无需伪造 parent 可见信号，就能等待 child 侧报告。
+ACP（Agent Client Protocol）快照 harness 新增 `waitForSubagentTurnEnd`，按与 `session.N.jsonl` 相同的顺序选择第 N 个已收集 child。它会等待一个包含请求 header 的已闭合 child 轮次，以防可继续 child 早期播种描述符的轮次错误满足该边界。这样，整体组装的场景无需伪造 parent 可见信号，就能等待 child 侧报告。
 
-手写快照会启动一个可继续 child，执行真实的作用域局部 `report` 工具，确认空闲 parent 未被唤醒，然后提交一条后续 parent 提示词，使其消费封装后的报告。它声明 child schema pin `1`，因此本不属于全局的 `report` schema 会与 `tool-schemas.1.expected.json` 比对，root 则继续使用默认 schema pin。生成的工具目录会另外铸造一个 child 作用域，以收录同一个作用域局部 schema。
+手写快照会启动一个可继续 child，执行真实的作用域局部 `report` 工具，观察默认唤醒投递所产生的那一个普通 parent 轮次，然后提交一条后续 parent 提示词，使其消费封装后的报告。它声明 child pin `1`，因此本不属于全局的 `report` schema 与该 child 自身的提示词会分别与 `tool-schemas.1.expected.json` 和 `system-prompt.1.expected.md` 比对，root 则继续使用类别 pin。生成的工具目录会另外铸造一个 child 作用域，以收录同一个作用域局部 schema。
 
 ## 曾考虑的替代方案
 
@@ -72,7 +72,7 @@ ACP（Agent Client Protocol）快照 harness 新增 `waitForSubagentTurnEnd`，
 
 ### 始终唤醒 parent
 
-每次报告都唤醒 parent 会产生未经请求的轮次，还可能沿嵌套 subagent 级联扩散。静默投递更适合作为后台协调的默认值，而需要立即处理的部署可选择 wakeup。
+每次报告都唤醒 parent 会产生未经请求的轮次，还可能沿嵌套 subagent 级联扩散。当初选择静默投递作为默认值，前提是 parent 还有别的理由去读自己的上下文。[报告义务](2026-08-06-continuable-child-report-obligation.md)取代了该选择：已经停驻的后台协调者并没有这样的理由，因此唤醒成为默认值，而本段现在记录的是 `quiet` 为何仍然保留。
 
 ### 允许 child 选择投递模式
 
@@ -103,16 +103,16 @@ ACP（Agent Client Protocol）快照 harness 新增 `waitForSubagentTurnEnd`，
 - 只有安装 report 包贡献时，可继续进程内 child 才会恰好暴露一个作用域局部 `report` schema；无关 Agent 永远不会暴露该 schema。
 - 工具返回 parent 消息的稳定 `MessageId`。静默投递没有 `InboxItemId`；唤醒投递会产生一个单独的 inbox 条目实例。
 - 只有确切的驻留 child 才能报告，且只能报告给根据持久化谱系推导的确切在线直接 parent。服务不接受接收方参数，也不提供离线 fallback。
-- 静默投递是校验后的默认模式，绝不会启动 parent 请求。wakeup 会恰好创建一个后续 FIFO 轮次，绝不 steering 已开始的轮次。
+- 唤醒投递是校验后的默认模式：它会恰好创建一个后续 FIFO 轮次，绝不 steering 已开始的轮次。静默投递则绝不会启动 parent 请求。
 - parent 接受后取消或 dispose child 不会撤回报告。接受前，child dispose、drain、parent 丢失或调用方取消都会拒绝操作。
 - 新建和恢复的 Activation 都会在发布前组合当前设置贡献。新授权等待下一个 Activation 才生效，而已驻留 child 的授权撤销立即生效。
 - 单元覆盖固定可见性、allow-list 行为、两种投递模式、稳定的消息与发送方身份、嵌套路由、无效发送方、缺失的 parent、取消、drain、撤销竞争，以及不存在 Task 或隐式最终报告。
-- 无密钥整体组装快照证明真实 child 工具、静默且不唤醒的行为、持久化 parent 封装，以及 parent 后续消费。
+- 无密钥整体组装快照证明真实 child 工具、那一个被唤醒的 parent 轮次、持久化 parent 封装，以及 parent 后续消费。
 
 ### 已接受的风险
 
 该接受边界弱于持久化端到端投递。崩溃可能导致结果不明，重试则可能重复报告。
 
-wakeup 模式可能在嵌套 child 频繁报告时放大模型工作量。由部署所有者控制并默认静默，可以限制该风险，但无法完全消除。
+唤醒投递可能在嵌套 child 频繁报告时放大模型工作量。通过 `reportDelivery` 交由部署所有者控制，可以限制该风险，但无法完全消除。
 
 注册表中的存在性就是 parent 在线信号。宿主拥有的 parent 如果已开始 `AgentHandle.dispose()` 但尚未完成其作用域清理，仍可能接受并追加一条本进程不会再处理的报告。要弥合这个缺口，需要 Agent 层面的 dispose 开始信号，不能由 subagent 层推断。

.agents/notes/implemented/feature/2026-08-06-continuable-child-report-obligation.i18n.yaml

@@ -0,0 +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 .agents/notes/implemented/feature/2026-08-06-continuable-child-report-obligation.md
+2026-08-06-continuable-child-report-obligation.md: ba52c72a94350d637699f778342093e71f2ed442
+2026-08-06-continuable-child-report-obligation.zh.md: 5c4178e0e095dac5b1e50ad92ef75d0138940439

.agents/notes/implemented/feature/2026-08-06-continuable-child-report-obligation.md

@@ -0,0 +1,60 @@
+# Agent Note: The continuable child return channel is an obligation
+
+Status: implemented
+
+English | [中文](2026-08-06-continuable-child-report-obligation.zh.md)
+
+## Problem
+
+A continuable background child owns its own Session, so nothing it writes there reaches the agent that started it. [The report tool](2026-07-30-continuable-subagent-report-tool.md) gave that child a return channel and then presented it as one option among several: the schema said "call this zero or more times", nothing in the child's prompt asked it to call the tool at all, and the accepted default scheduling (`quiet`) added the report to a parked parent's next request without waking it.
+
+Each of those choices is defensible alone. Together they made the return channel unusable as a delegation contract. A child that finished its work, wrote its answer into its own transcript, and stopped left the parent with nothing; a child that did report reached a parent that had already parked and would not read the report until something unrelated woke it. External reports of parents busy-polling `list_agents`, re-sending messages to settled children, and abandoning `subagent` for `workflow` all reduce to the same missing guarantee.
+
+## Decision
+
+The return channel is an instruction the child receives, not a capability it may discover. The report package installs two scope-local registrations into every continuable in-process child, and one disposer revokes both:
+
+- the `report` tool, whose description now states that the child calls it once before finishing with a self-contained final result, and earlier for progress that changes what the parent should do next;
+- a `tool:report` system-prompt section at order 117 carrying the same obligation in the child's own voice, so a child that never reads tool descriptions closely still receives it.
+
+`reportDelivery` now defaults to `wakeup`. An accepted report creates exactly one ordinary later parent turn and wakes a parked parent driver; it still never steers an open turn. `quiet` remains available for deployments that prefer unread reports over turn amplification.
+
+### Why the section and the description both exist
+
+They address different failure modes. The tool description is read when the model is already considering `report`; the prompt section is read when it is deciding whether it is finished. The obligation belongs at both points because the failure this fixes — a child that simply stops — happens at the second one.
+
+The section is registered on the child's own scope, the same mechanism [child composition](../../../../packages/subagent/subagent/src/child-agent.ts) already uses for a shadowing persona, so the parent and every sibling see neither the tool nor the guidance. `installReportTool` rolls the section back if tool registration fails, and its returned disposer attempts both revocations before surfacing cleanup failures.
+
+### Instruction, not enforcement
+
+Nothing rejects a child that never reports. No runtime path inspects whether a report was sent, and `report` still accepts zero or many calls per turn. The change is model-facing wording plus a scheduling default; the service authority, acknowledgement, and recovery contracts are unchanged.
+
+That boundary is deliberate: prompt text can only reach a child that is still running its own loop. A child stopped by an error, a token ceiling, cancellation, or teardown never gets the chance to comply. Covering those cases needs an account the runtime keeps itself, which this package cannot supply and does not claim to.
+
+### Snapshot coverage
+
+The assembled ACP `subagent-report` scenario now exercises the shipped default: the child reports, the parked parent takes one ordinary turn on that report, and a later prompt still reads the report back out of the durable log. Because the child's scope now composes a prompt the class pin cannot describe, the snapshot harness gained `pinsChildSystemPrompts`, the exact counterpart of the existing `pinsChildToolSchemas`: it moves one child fixture's prompt into `system-prompt.<n>.expected.md`, leaves every other request-header field to the class pin, requires the sidecar exactly when declared, and rejects a sidecar identical to that class pin so a redundant copy cannot drift.
+
+## Alternatives considered
+
+**Keep `quiet` as the default and rely on the prompt alone.** This was the shipped position, and it supersedes nothing on its own: a report the parent never reads is indistinguishable from a report never sent. The [report-tool note's](2026-07-30-continuable-subagent-report-tool.md) rejection of always-waking assumed the parent had another reason to look at its context; a parked background coordinator does not. Turn amplification is the real cost, and it is now the reason `quiet` still exists rather than the reason it is the default.
+
+**Let the child choose the delivery mode per call.** Unchanged from the original rejection: the model would own scheduler pressure, and behavior would vary per call rather than per deployment.
+
+**Put the obligation only in the tool description.** A description is read while choosing among tools. The child this change targets is not choosing a tool; it believes it is done. Prompt guidance is the surface that reaches that decision.
+
+**Enforce the obligation at settlement by rejecting a silent child.** There is nothing to reject: by the time settlement is observable the child's loop is over, and failing its teardown would destroy work rather than deliver it. Delivering the terminal facts unconditionally from the runtime is the answer to that case, and it belongs to the continuation manager, not to this package.
+
+## Consequences
+
+- Every continuable in-process child with this package loaded carries one extra prompt section and a longer `report` description in every request; no other Agent's request changes.
+- The default deployment wakes the parent once per accepted report. A nested tree that reports frequently consumes extra parent turns; `quiet` is the documented escape.
+- `installReportTool` requires `ctx.systemPrompt` in the child scope, so the package declares `systemPrompt` in `inject` and fails at load rather than at the next child materialization.
+- Unit coverage pins the new default, two load-bearing instruction phrases, the section's child-only scope against both the parent and a sibling, and rollback or revocation of both registrations.
+- Three assembled ACP scenarios with continuable children pin the complete instruction text through the new sidecar; a future change to any child-scoped section fails those scenarios instead of passing silently.
+
+### Accepted risks
+
+Waking by default amplifies model work in deep trees. The deployment owns that through `reportDelivery`, and the amplification is bounded by one turn per accepted report.
+
+A child can still finish without reporting, and this change cannot detect it. Closing that case needs the runtime's own settlement account, which this package does not own.

.agents/notes/implemented/feature/2026-08-06-continuable-child-report-obligation.zh.md

@@ -0,0 +1,60 @@
+# Agent Note: 可继续 child 的返回通道是一项义务
+
+Status: implemented
+
+[English](2026-08-06-continuable-child-report-obligation.md) | 中文
+
+## 问题
+
+可继续后台 child 拥有自己的 Session，因此它写在那里的任何内容都不会到达启动它的 agent。[report 工具](2026-07-30-continuable-subagent-report-tool.md)为该 child 提供了一条返回通道，却把它呈现为若干选项之一：schema 里写着「可调用零次或多次」，child 的提示词中没有任何地方要求它调用该工具，而已采纳的默认调度（`quiet`）会把报告加入已停驻 parent 的下一次请求，却不唤醒它。
+
+这些选择单独看都站得住脚。合在一起，它们让这条返回通道无法作为委派契约使用。一个完成工作、把答案写进自己 transcript（文本记录）随后停止的 child，会让 parent 一无所获；而确实上报了的 child，面对的是一个已经停驻、要等到别的事件把它唤醒才会读到报告的 parent。外部反馈中的 parent 忙轮询 `list_agents`、反复向已结算 child 发送消息、以及放弃 `subagent` 改用 `workflow`，都可归结为同一处缺失的保证。
+
+## 决策
+
+返回通道是 child 收到的一条指令，而不是它需要自行发现的能力。report 包会向每个可继续进程内 child 安装两项作用域局部注册，并由同一个 disposer 撤销两者：
+
+- `report` 工具，其描述现在说明 child 要在结束前调用一次并给出自足的最终结果，并在部分进展会改变 parent 下一步动作时提前调用；
+- 一个 order 为 117 的 `tool:report` 系统提示词 section，用 child 自己的语气承载同一条义务，使从不细读工具描述的 child 仍能收到它。
+
+`reportDelivery` 的默认值现在是 `wakeup`。一条被接受的报告恰好创建一个普通的后续 parent 轮次并唤醒停驻的 parent 驱动；它仍然绝不 steering（中途引导）已开始的轮次。对于宁可让报告无人阅读也要避免轮次放大的部署，`quiet` 依旧可用。
+
+### 为什么 section 与描述同时存在
+
+两者针对不同的失效模式。工具描述是在模型已经在考虑 `report` 时被读到的；提示词 section 是在它判断自己是否已经完成时被读到的。这条义务必须同时出现在两处，因为本次修复的失效——child 直接停下——发生在第二处。
+
+该 section 注册在 child 自己的作用域上，与[child 组合](../../../../packages/subagent/subagent/src/child-agent.ts)为遮蔽式 persona 已经使用的机制相同，因此 parent 与所有同级都看不到该工具与该指引。工具注册失败时，`installReportTool` 会回滚该 section；它返回的 disposer 会先尝试撤销两项注册，再抛出清理失败。
+
+### 是指令，不是强制
+
+没有任何东西会拒绝一个从不上报的 child。没有任何运行时路径会检查是否发送过报告，`report` 仍接受一个轮次中调用零次或多次。本次改动是面向模型的措辞加上一个调度默认值；服务权限、确认与恢复契约都保持不变。
+
+这条边界是刻意划定的：提示词文本只能到达仍在运行自身循环的 child。被错误、token 上限、取消或拆卸终止的 child 根本没有机会遵守。覆盖这些情形需要由运行时自己保存的记账，而本包无法提供，也不声称提供。
+
+### 快照覆盖
+
+整体组装的 ACP `subagent-report` 场景现在演练随附的默认行为：child 上报，停驻的 parent 就该报告执行一个普通轮次，随后的提示词仍能从持久化日志中把报告读回来。由于该 child 的作用域现在组合出类别 pin 无法描述的提示词，快照 harness 新增了 `pinsChildSystemPrompts`，它与既有 `pinsChildToolSchemas` 完全对称：把一个 child fixture 的提示词移入 `system-prompt.<n>.expected.md`，其余请求 header 字段仍归类别 pin 所有，要求 sidecar 恰好在声明时存在，并拒绝与该类别 pin 完全相同的 sidecar，使冗余副本无法悄悄漂移。
+
+## 备选方案
+
+**保留 `quiet` 作为默认值，只依赖提示词。** 这曾是随附的立场，而它本身什么也没有解决：一条 parent 从不阅读的报告，与一条从未发送的报告无法区分。[report 工具 Agent Note](2026-07-30-continuable-subagent-report-tool.md)对「始终唤醒」的否决，前提是 parent 还有别的理由去查看自己的上下文；已停驻的后台协调者并没有。轮次放大才是真正的代价，而它现在是 `quiet` 仍然保留的理由，而不是它作为默认值的理由。
+
+**让 child 按调用选择投递模式。** 与最初的否决相同：模型将掌握调度压力，行为也会随调用而非随部署变化。
+
+**只把义务写在工具描述里。** 描述是在从多个工具中选择时被读到的。本次改动针对的 child 并不在选择工具，它认为自己已经做完了。提示词指引才是能触及该判断的界面。
+
+**在结算时拒绝沉默的 child，以此强制该义务。** 没有什么可以拒绝：当结算可被观察时 child 的循环已经结束，让它的拆卸失败只会毁掉工作而不会送达结果。由运行时无条件投递终止事实才是这一情形的答案，而它属于继续执行管理器，不属于本包。
+
+## 后果
+
+- 加载本包后，每个可继续进程内 child 的每次请求都会多出一个提示词 section 和一段更长的 `report` 描述；其他任何 Agent 的请求都不变。
+- 默认部署会为每条被接受的报告唤醒 parent 一次。频繁上报的嵌套树会消耗额外的 parent 轮次；`quiet` 是有文档记载的退路。
+- `installReportTool` 需要 child 作用域中的 `ctx.systemPrompt`，因此本包在 `inject` 中声明 `systemPrompt`，从而在加载时失败，而不是等到下一次 child 物化时。
+- 单元覆盖固定了新默认值、两处关键指令措辞、该 section 相对 parent 与同级均仅限 child 的作用域，以及两项注册在安装回滚或撤销时的清理。
+- 三个带可继续 child 的整体组装 ACP 场景通过新的 sidecar 逐字固定完整的 child 提示词；今后任何对 child 作用域 section 的改动都会让这些场景失败，而不是悄悄通过。
+
+### 已接受的风险
+
+默认唤醒会在深层树中放大模型工作量。部署通过 `reportDelivery` 掌握该取舍，且放大幅度以每条被接受报告一个轮次为界。
+
+child 仍可能不上报就结束，本次改动无法检测这一点。补上这一情形需要运行时自己的结算记账，而本包并不拥有它。