fix(user-interaction): reject ask_user_question from delegated subagents

packages/ui/user-interaction/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/ui/user-interaction/README.md
-README.md: d62e75d110b8be339c5f9449b0834320f695ac99
-README.zh.md: 55258e85e56df2375ed8f195fa0b3b731a9cb816
+README.md: 3459f915f2cd94d4083975440731661d8aeb9108
+README.zh.md: 26d40e98dbcc15ef18a85cd98205defb765d4469

packages/ui/user-interaction/README.md

@@ -18,7 +18,7 @@ Abstract user-interaction seam. It owns `ctx.userInteraction`, the service a mod
 - `AskUserQuestionIntent` — `{ kind: 'plan-review', approve }`; the tagged presentation intent below.
 - `AskUserQuestionAnswer` — `{ answers: [{ id, selected, custom? }] }`.
 - `UserInteractionProvider` — UI implementation with `ask(request)`.
-- `UserInteractionError` — `HarnessError` subclass with codes such as `EMPTY_QUESTIONS`, `BAD_INTENT`, `NO_PROVIDER`, `DUPLICATE_PROVIDER`, and `ASK_ABORTED`.
+- `UserInteractionError` — `HarnessError` subclass with codes such as `EMPTY_QUESTIONS`, `BAD_INTENT`, `NO_PROVIDER`, `DUPLICATE_PROVIDER`, `ASK_ABORTED`, and `DELEGATED_CALLER`.
 
 When an answer includes `custom`, `selected` is empty; custom text is an override rather than a supplement to selected choices. A UI may preserve a skipped item as `{ id, selected: [] }`, keeping the existing answer shape while retaining other answers in the batch.
 
@@ -32,7 +32,7 @@ This is the interface package. Model-facing consumers such as `@deepseek-ai/dsh-
 
 ## Model Experience
 
-Indirectly, through `dsh-tool-ask-user`, which retains a successful provider answer as compact JSON or one of these failures: `Error: ask_user_question was aborted before the user answered`, `Error: ask_user_question requires at least one question`, `Error: no user-interaction provider is registered`, or `Error: <message>`. Waiting for the human adds no tokens.
+Indirectly, through `dsh-tool-ask-user`, which retains a successful provider answer as compact JSON or one of these failures: `Error: ask_user_question was aborted before the user answered`, `Error: ask_user_question requires at least one question`, `Error: ask_user_question is unavailable to delegated subagents; delegate the question to the top-level agent`, `Error: no user-interaction provider is registered`, or `Error: <message>`. Waiting for the human adds no tokens.
 
 #### KV Cache effect
 

packages/ui/user-interaction/README.zh.md

@@ -18,7 +18,7 @@
 - `AskUserQuestionIntent`：`{ kind: 'plan-review', approve }`；即下文的带标签呈现意图。
 - `AskUserQuestionAnswer`：`{ answers: [{ id, selected, custom? }] }`。
 - `UserInteractionProvider`：包含 `ask(request)` 的 UI 实现。
-- `UserInteractionError`：`HarnessError` 的子类，包含 `EMPTY_QUESTIONS`、`BAD_INTENT`、`NO_PROVIDER`、`DUPLICATE_PROVIDER` 和 `ASK_ABORTED` 等代码。
+- `UserInteractionError`：`HarnessError` 的子类，包含 `EMPTY_QUESTIONS`、`BAD_INTENT`、`NO_PROVIDER`、`DUPLICATE_PROVIDER`、`ASK_ABORTED` 和 `DELEGATED_CALLER` 等代码。
 
 当回答包含 `custom` 时，`selected` 为空；自定义文本是所选选项的替代，而不是补充。UI 可以把跳过的条目保留为 `{ id, selected: [] }`，既维持现有回答形态，也保留该批次中的其他回答。
 
@@ -32,7 +32,7 @@
 
 ## 模型体验
 
-间接地，通过 `dsh-tool-ask-user`：它会将成功的提供方回答保留为紧凑 JSON，或返回以下失败之一：`Error: ask_user_question was aborted before the user answered`、`Error: ask_user_question requires at least one question`、`Error: no user-interaction provider is registered` 或 `Error: <message>`。等待人类回答不会增加 token。
+间接地，通过 `dsh-tool-ask-user`：它会将成功的提供方回答保留为紧凑 JSON，或返回以下失败之一：`Error: ask_user_question was aborted before the user answered`、`Error: ask_user_question requires at least one question`、`Error: ask_user_question is unavailable to delegated subagents; delegate the question to the top-level agent`、`Error: no user-interaction provider is registered` 或 `Error: <message>`。等待人类回答不会增加 token。
 
 #### KV Cache 影响
 

packages/ui/user-interaction/src/index.ts

@@ -77,8 +77,15 @@ export class UserInteractionService extends Service {
   /**
    * Ask the active UI provider and wait for the user's answer.
    *
+   * Human-interaction requests are only valid from a top-level agent: a
+   * delegated subagent has no human answerer in its own context, so asking
+   * there would block forever. This mirrors the goal tools' top-level-only
+   * authority (`create_goal` rejects non-top-level agents).
+   *
    * @param request Questions, owner agent, and abort signal.
    * @returns The answer chosen or typed by the human.
+   * @throws {UserInteractionError} code `DELEGATED_CALLER` when the calling
+   *   agent is a delegated subagent (`session.header.delegationDepth > 0`).
    */
   async ask(request: AskUserQuestionRequest): Promise<AskUserQuestionAnswer> {
     if (request.signal?.aborted) {
@@ -87,6 +94,11 @@ export class UserInteractionService extends Service {
     if (request.questions.length === 0) {
       throw new UserInteractionError('ask_user_question requires at least one question', 'EMPTY_QUESTIONS')
     }
+    if ((request.agent?.session.header.delegationDepth ?? 0) > 0) {
+      throw new UserInteractionError(
+        'ask_user_question is unavailable to delegated subagents; delegate the question to the top-level agent',
+        'DELEGATED_CALLER')
+    }
     // A presentation intent asserts two things the types cannot: that the
     // named approve label is one of this question's own options, and that a
     // plan-review carries the plan it is a review of. A UI honouring the

packages/ui/user-interaction/tests/user-interaction.spec.ts

@@ -1,5 +1,7 @@
 import { describe, expect, it, vi } from 'vitest'
 import { Context } from 'cordis'
+import type { Agent } from '@deepseek-ai/dsh-agent'
+import SessionStore from '@deepseek-ai/dsh-session'
 import UserInteractionService, {
   UserInteractionError,
   type AskUserQuestionRequest,
@@ -84,6 +86,39 @@ describe('UserInteractionService', () => {
     expect(p.ask).not.toHaveBeenCalled()
   })
 
+  it('rejects a delegated subagent before reaching the provider', async () => {
+    const ctx = new Context()
+    await ctx.plugin(SessionStore)
+    await ctx.plugin(UserInteractionService)
+    const p = { ask: vi.fn(async () => ({ answers: [] })) }
+    ctx.userInteraction.registerProvider(p)
+    const session = ctx.sessions.create(undefined, { meta: { delegationDepth: 1 } })
+    const agent = { session } as unknown as Agent
+
+    await expect(ctx.userInteraction.ask({
+      questions: [{ id: 'confirm', question: 'Proceed?' }],
+      agent,
+    })).rejects.toMatchObject({ name: 'UserInteractionError', code: 'DELEGATED_CALLER' })
+    expect(p.ask).not.toHaveBeenCalled()
+  })
+
+  it('still reaches the provider for a top-level agent (delegationDepth 0)', async () => {
+    const ctx = new Context()
+    await ctx.plugin(SessionStore)
+    await ctx.plugin(UserInteractionService)
+    const p = provider('yes')
+    ctx.userInteraction.registerProvider(p)
+    const session = ctx.sessions.create(undefined, { meta: { delegationDepth: 0 } })
+    const agent = { session } as unknown as Agent
+
+    const result = await ctx.userInteraction.ask({
+      questions: [{ id: 'confirm', question: 'Proceed?' }],
+      agent,
+    })
+
+    expect(result).toEqual({ answers: [{ id: 'confirm', selected: ['yes'] }] })
+  })
+
   it('rejects an intent whose approve label names none of its own options', async () => {
     const ctx = new Context()
     await ctx.plugin(UserInteractionService)