deepseek-harness/packages/subagent/subagent-inprocess/tests/structured.spec.ts

import { describe, expect, it } from 'vitest'
import { Context } from '@deepseek-ai/cordis'
import { createUserMessage, CallId, type ContentBlock, type GenerateOptions } from '@deepseek-ai/dsh-llm'
import { SessionId } from '@deepseek-ai/dsh-session'
import AgentLoop from '@deepseek-ai/dsh-agent-loop'
import { mountAgentLoopTestDependencies } from '@deepseek-ai/dsh-agent-loop-testkit'
import InvariantService from '@deepseek-ai/dsh-invariants'
import * as SessionInvariant from '@deepseek-ai/dsh-session/invariant'
import * as AgentInvariant from '@deepseek-ai/dsh-agent/invariant'
import * as AgentLoopInvariant from '@deepseek-ai/dsh-agent-loop/invariant'
import SubagentService, {
  type ResolvedSubagentStartRequest,
  type SubagentStartRequest,
} from '@deepseek-ai/dsh-subagent'
import type { Config as ToolConfig, ObjectJsonSchema } from '@deepseek-ai/dsh-tools'
import { defineContentToolFixture, RUN_CODE_NAME } from '@deepseek-ai/dsh-tools'
import { MockAdapter, textResponse, toolCallResponse } from '../../../core/agent-loop/tests/mock-adapter.ts'
import { startInProcessRun } from '../src/index.ts'
import {
  STRUCTURED_OUTPUT_INSTRUCTION,
  STRUCTURED_OUTPUT_TOOL,
} from '../src/structured.ts'

const testToolSignal = new AbortController().signal

type Script = ConstructorParameters<typeof MockAdapter>[0]

async function mountInvariants(ctx: Context): Promise<void> {
  await ctx.plugin(InvariantService)
  await ctx.plugin(SessionInvariant)
  await ctx.plugin(AgentInvariant)
  await ctx.plugin(AgentLoopInvariant)
}

interface CodeRunRequestLike {
  bindings: { global: string; functions: Record<string, (args: unknown) => Promise<unknown>> }[]
}

interface SetupOptions {
  toolMode?: ToolConfig['mode']
  codeRun?: (request: CodeRunRequestLike) => Promise<{ logs: never[]; value?: unknown }>
}

const SCHEMA: ObjectJsonSchema = {
  type: 'object',
  properties: { answer: { type: 'number' }, note: { type: 'string' } },
  required: ['answer'],
}

/**
 * Real loop, scripted model, and inline fresh-conversation provider over the shared driver. Loading
 * spawn/fork here would create a dev-dependency cycle; their specs cover plugin integration while
 * this fixture isolates driver behavior and scripts the child's `structured_output` calls.
 */
async function setup(script: Script, options: SetupOptions = {}) {
  const ctx = new Context()
  const adapter = new MockAdapter(script)
  await mountAgentLoopTestDependencies(ctx, {
    tools: { mode: options.toolMode ?? 'native' },
  })
  if (options.toolMode === 'code' || options.toolMode === 'both') {
    ctx.provide('codeRuntime', {
      language: 'typescript',
      isolation: 'test',
      run: options.codeRun ?? (() => Promise.resolve({ logs: [] })),
    } as never)
  }
  await mountInvariants(ctx)
  await ctx.plugin(AgentLoop, { agents: [] })
  await ctx.plugin(SubagentService)
  const disposeProvider = ctx.subagents.registerProvider({
    name: 'spawn',
    capabilities: { outputSchema: true, depthLimit: true, toolFilter: false, persona: false },
    inheritsParentContext: false,
    start: (request: ResolvedSubagentStartRequest) => startInProcessRun(request, {}),
  })
  ctx.llm.registerAdapter(['mock'], adapter)
  const parent = ctx.agentLoop.create(SessionId('parent'), { provider: 'mock', model: 'mock' })
  return { ctx, parent, adapter, disposeProvider }
}

function structuredRequest(parent: SubagentStartRequest['parent'], extra?: Partial<SubagentStartRequest>): SubagentStartRequest {
  return {
    label: 'produce the answer',
    prompt: [{ type: 'text', text: 'produce the answer' }],
    parent,
    signal: new AbortController().signal,
    outputSchema: SCHEMA,
    ...extra,
  }
}

/** The tool names of one recorded model request. */
function toolNames(request: GenerateOptions): string[] {
  return (request.tools ?? []).map(tool => tool.name)
}

describe('in-process structured output', () => {
  it('captures a valid structured_output call and surfaces result.structured', async () => {
    const { ctx, parent } = await setup([
      toolCallResponse('c1', STRUCTURED_OUTPUT_TOOL, { answer: 42, note: 'done' }),
    ])
    let acknowledgement: unknown
    ctx.on('tools/result', (exec, toolResult) => {
      if (exec.name === STRUCTURED_OUTPUT_TOOL && !toolResult.isError) acknowledgement = toolResult.value
    })
    const run = await ctx.subagents.start('spawn', structuredRequest(parent))
    const result = await run.result
    expect(result.stopReason).toBe('completed')
    expect(result.structured).toEqual({ answer: 42, note: 'done' })
    expect(acknowledgement).toEqual({ recorded: true })
    await run.dispose()
  })

  it('stops the turn after a successful capture — no extra model step is spent', async () => {
    const { ctx, parent, adapter } = await setup([
      toolCallResponse('c1', STRUCTURED_OUTPUT_TOOL, { answer: 1 }),
      textResponse('MUST NOT BE CONSUMED'),
    ])
    const run = await ctx.subagents.start('spawn', structuredRequest(parent))
    await run.result
    // The structured tool marks its successful result as turn-concluding.
    expect(adapter.requests.length).toBe(1)
    await run.dispose()
  })

  it('denies tool calls that FOLLOW the capture in the same response — terminal means terminal', async () => {
    // One model response carrying structured_output FIRST and a side-effecting
    // call after it: the continuation veto only fires at step end, so without
    // the pre-execute deny the trailing call would still run after the final
    // answer was accepted.
    const response = [
      ...toolCallResponse('c1', STRUCTURED_OUTPUT_TOOL, { answer: 5 }).slice(0, -2),
      { type: 'block-start', index: 1, blockType: 'tool-call' },
      { type: 'block-end', index: 1, block: { type: 'tool-call', id: CallId('c2'), name: 'side_effect', arguments: '{}' } },
      { type: 'usage', usage: { inputTokens: 10, outputTokens: 5 } },
      { type: 'finish', reason: { kind: 'tool-calls' } },
    ] as Script[number]
    const { ctx, parent } = await setup([response])
    let sideEffectRan = false
    ctx.tools.register(defineContentToolFixture({
      name: 'side_effect',
      description: 'probe',
      parameters: {},
      execute(): Promise<ContentBlock[]> {
        sideEffectRan = true
        return Promise.resolve([{ type: 'text', text: 'ran' }])
      },
    }))
    const run = await ctx.subagents.start('spawn', structuredRequest(parent))
    const result = await run.result
    expect(result.stopReason).toBe('completed')
    expect(result.structured).toEqual({ answer: 5 })
    // The deny skipped dispatch entirely: the probe body never ran.
    expect(sideEffectRan).toBe(false)
    await run.dispose()
  })

  it('a later prepended pre-execute listener cannot resurrect dispatch after capture', async () => {
    const response = [
      ...toolCallResponse('c1', STRUCTURED_OUTPUT_TOOL, { answer: 5 }).slice(0, -2),
      { type: 'block-start', index: 1, blockType: 'tool-call' },
      { type: 'block-end', index: 1, block: { type: 'tool-call', id: CallId('c2'), name: 'side_effect', arguments: '{}' } },
      { type: 'usage', usage: { inputTokens: 10, outputTokens: 5 } },
      { type: 'finish', reason: { kind: 'tool-calls' } },
    ] as Script[number]
    const { ctx, parent } = await setup([response])
    let sideEffectRan = false
    ctx.tools.register(defineContentToolFixture({
      name: 'side_effect',
      description: 'probe',
      parameters: {},
      execute(): Promise<ContentBlock[]> {
        sideEffectRan = true
        return Promise.resolve([{ type: 'text', text: 'ran' }])
      },
    }))
    const run = await ctx.subagents.start('spawn', structuredRequest(parent))
    // Registered after the child and prepended: this listener returns allow
    // after every downstream pre-execute decision. The service-owned guard
    // runs after the waterfall and can only deny, so the body still cannot run.
    ctx.on('tools/pre-execute', async (_exec, next) => {
      await next()
      return { kind: 'allow' as const }
    }, { prepend: true })

    const result = await run.result
    expect(result.structured).toEqual({ answer: 5 })
    expect(sideEffectRan).toBe(false)
    const child = ctx.agents.get(run.id)
    const sideEffectResult = child?.session.events.find(event =>
      event.type === 'tool/result' && event.data.message.source.callId === 'c2')
    expect(sideEffectResult?.type === 'tool/result' && sideEffectResult.data.message.content[0].isError).toBe(true)
    await run.dispose()
  })

  it('leaves tool calls that PRECEDE the capture in the same response untouched', async () => {
    const response = [
      { type: 'block-start', index: 0, blockType: 'tool-call' },
      { type: 'block-end', index: 0, block: { type: 'tool-call', id: CallId('c1'), name: 'side_effect', arguments: '{}' } },
      ...toolCallResponse('c2', STRUCTURED_OUTPUT_TOOL, { answer: 6 }).map(chunk =>
        'index' in chunk ? { ...chunk, index: 1 } : chunk),
    ] as Script[number]
    const { ctx, parent } = await setup([response])
    let sideEffectRan = false
    ctx.tools.register(defineContentToolFixture({
      name: 'side_effect',
      description: 'probe',
      parameters: {},
      execute(): Promise<ContentBlock[]> {
        sideEffectRan = true
        return Promise.resolve([{ type: 'text', text: 'ran' }])
      },
    }))
    const run = await ctx.subagents.start('spawn', structuredRequest(parent))
    const result = await run.result
    // The call ran BEFORE captured was set: the deny gate only guards the
    // window after the terminal answer landed.
    expect(sideEffectRan).toBe(true)
    expect(result.structured).toEqual({ answer: 6 })
    await run.dispose()
  })

  it('an invalid call gets an INVALID_ARGS isError result and the model retries in-turn', async () => {
    const { ctx, parent } = await setup([
      toolCallResponse('c1', STRUCTURED_OUTPUT_TOOL, { answer: 'not-a-number' }),
      toolCallResponse('c2', STRUCTURED_OUTPUT_TOOL, { answer: 7 }),
    ])
    const run = await ctx.subagents.start('spawn', structuredRequest(parent))
    const result = await run.result
    expect(result.structured).toEqual({ answer: 7 })
    expect(result.stopReason).toBe('completed')
    // The child's log carries the isError tool/result for the invalid call.
    const child = ctx.agents.get(run.id)!
    const results = child.session.events.filter(e => e.type === 'tool/result')
    expect(results.length).toBe(2)
    expect(results[0]!.data.message.content[0].isError).toBe(true)
    await run.dispose()
  })

  it('a clean finish without a capture is an immediate error to the parent — deliberately NO re-prompt', async () => {
    const { ctx, parent, adapter } = await setup([
      textResponse('here is my answer in prose'),
      textResponse('MUST NOT BE CONSUMED'),
    ])
    const run = await ctx.subagents.start('spawn', structuredRequest(parent))
    const result = await run.result
    expect(result.stopReason).toBe('error')
    expect(result.structured).toBeUndefined()
    // Exactly one model request and one caller-supplied user message: no nudge turn exists.
    expect(adapter.requests.length).toBe(1)
    const child = ctx.agents.get(run.id)!
    expect(child.session.events.filter(e => e.type === 'user/message' && e.data.source.kind !== 'plugin').length).toBe(1)
    await run.dispose()
  })

  it('an errored child keeps its honest error result (no capture expected)', async () => {
    // Script exhaustion on the first call → the child turn errors.
    const { ctx, parent, adapter } = await setup([])
    const run = await ctx.subagents.start('spawn', structuredRequest(parent))
    const result = await run.result
    expect(result.stopReason).toBe('error')
    expect(adapter.requests.length).toBe(1)
    await run.dispose()
  })

  it('a cancel landing after a clean capture-less turn settles aborted, not error', async () => {
    const { ctx, parent } = await setup([textResponse('prose, no capture')])
    const controller = new AbortController()
    const run = await ctx.subagents.start('spawn', structuredRequest(parent, { signal: controller.signal }))
    // Cancel synchronously inside the turn's end recording: the cancel
    // contract outranks the schema shortfall, so the result maps to aborted.
    ctx.on('session/event', (session, event) => {
      const child = ctx.agents.get(run.id)
      if (session === child?.session && event.type === 'turn/end') controller.abort('cancelled at turn end')
    })
    const result = await run.result
    expect(result.stopReason).toBe('aborted')
    await run.dispose()
  })

  it('rejects a schema outside the subset loud, before any child exists', async () => {
    const { ctx, parent } = await setup([])
    await expect(ctx.subagents.start('spawn', structuredRequest(parent, {
      outputSchema: { type: 'object', oneOf: [] } as unknown as ObjectJsonSchema,
    }))).rejects.toThrow(/unsupported JSON schema/)
    expect(ctx.agents.get(SessionId('parent'))).toBeDefined()
  })

  it('a schema carrying non-JSON values fails as JsonSchemaError at the validation boundary', async () => {
    const { ctx, parent } = await setup([])
    // Semantic assertion runs before provider startup.
    await expect(ctx.subagents.start('spawn', structuredRequest(parent, {
      outputSchema: { type: 'object', default: () => {} } as unknown as ObjectJsonSchema,
    }))).rejects.toThrow(/unsupported JSON schema.*annotation must be lossless JSON data/)
  })

  it('a post-execute BLOCK on the capture call denies the capture: log and result agree on failure', async () => {
    const { ctx, parent, adapter } = await setup([
      toolCallResponse('c1', STRUCTURED_OUTPUT_TOOL, { answer: 7 }),
      textResponse('continues after the blocked capture'),
    ])
    // A PostToolUse-style hook turns the tool body's provisional success into
    // the authoritative final error observed by the commit notification.
    ctx.on('tools/post-execute', (exec, _result, next) => {
      if (exec.name === STRUCTURED_OUTPUT_TOOL) {
        return Promise.resolve({ kind: 'block' as const, feedback: [{ type: 'text' as const, text: 'capture rejected by hook' }] })
      }
      return next()
    })
    const run = await ctx.subagents.start('spawn', structuredRequest(parent))
    const result = await run.result
    // No capture was committed: the run reports the schema shortfall...
    expect(result.structured).toBeUndefined()
    expect(result.stopReason).toBe('error')
    // ...the logged tool result is the blocked isError with the feedback...
    const child = ctx.agents.get(run.id)!
    const results = child.session.events.filter(e => e.type === 'tool/result')
    expect(results[0]!.data.message.content[0].isError).toBe(true)
    expect(JSON.stringify(results[0]!.data.message.content)).toContain('capture rejected by hook')
    // ...and the turn CONTINUED past the blocked call (no captured veto):
    // the model got to react to the failure with a second step.
    expect(adapter.requests.length).toBe(2)
    await run.dispose()
  })

  it('a post-execute accept-with-replacement still commits the capture', async () => {
    const { ctx, parent } = await setup([
      toolCallResponse('c1', STRUCTURED_OUTPUT_TOOL, { answer: 8 }),
    ])
    ctx.on('tools/post-execute', (exec, _result, next) => {
      if (exec.name === STRUCTURED_OUTPUT_TOOL) {
        return Promise.resolve({ kind: 'accept' as const, content: [{ type: 'text' as const, text: 'recorded (rewritten)' }] })
      }
      return next()
    })
    const run = await ctx.subagents.start('spawn', structuredRequest(parent))
    const result = await run.result
    expect(result.stopReason).toBe('completed')
    expect(result.structured).toEqual({ answer: 8 })
    await run.dispose()
  })

  it('commits only after a later prepended post-execute wrapper returns the authoritative result', async () => {
    const { ctx, parent } = await setup([
      toolCallResponse('c1', STRUCTURED_OUTPUT_TOOL, { answer: 8 }),
      textResponse('capture was rejected'),
    ])
    const run = await ctx.subagents.start('spawn', structuredRequest(parent))
    // Registered after attachment and prepended, so it wraps every listener
    // the child installed. It delegates first, then converts the apparent
    // capture success into the pipeline's authoritative failure.
    ctx.on('tools/post-execute', async (exec, _result, next) => {
      const downstream = await next()
      if (exec.name !== STRUCTURED_OUTPUT_TOOL) return downstream
      return { kind: 'block' as const, feedback: [{ type: 'text' as const, text: 'rejected after downstream' }] }
    }, { prepend: true })

    const result = await run.result
    expect(result.structured).toBeUndefined()
    expect(result.stopReason).toBe('error')
    const child = ctx.agents.get(run.id)
    const captureResult = child?.session.events.find(event =>
      event.type === 'tool/result' && event.data.message.source.callId === 'c1')
    expect(captureResult?.type === 'tool/result' && captureResult.data.message.content[0].isError).toBe(true)
    await run.dispose()
  })

  it('appends the structured instruction to the child REQUEST\'s system text (base prompt preserved)', async () => {
    const { ctx, parent, adapter } = await setup([toolCallResponse('c1', STRUCTURED_OUTPUT_TOOL, { answer: 1 })])
    // A context-wide section stands in for the deployment persona: the
    // instruction must APPEND to the other scoped and global sections, not
    // replace them (AgentOptions has no prompt field — the instruction is an
    // ordinary child-scoped prompt registration).
    ctx.systemPrompt.section({ name: 'test:persona', order: 10, text: 'You are a counter.' })
    const run = await ctx.subagents.start('spawn', structuredRequest(parent))
    await run.result
    const childRequest = adapter.requests.at(-1)!
    expect(childRequest.system).toContain('You are a counter.')
    expect(childRequest.system!.endsWith(STRUCTURED_OUTPUT_INSTRUCTION)).toBe(true)
    expect(childRequest.system!.indexOf(STRUCTURED_OUTPUT_INSTRUCTION)).toBeGreaterThan(0)
    await run.dispose()
  })

  it('keeps pure Code Mode at one wire tool and exposes structured capture through the SDK only', async () => {
    const { ctx, parent, adapter } = await setup([
      toolCallResponse('c1', RUN_CODE_NAME, { code: 'return await tools.structured_output({ answer: 12 })', description: 'Capture the structured answer' }),
    ], {
      toolMode: 'code',
      codeRun: async (request) => {
        const capture = request.bindings.at(0)?.functions[STRUCTURED_OUTPUT_TOOL]
        if (!capture) throw new Error('structured_output binding missing')
        await capture({ answer: 12 })
        return { logs: [], value: 'captured' }
      },
    })
    const run = await ctx.subagents.start('spawn', structuredRequest(parent))

    const result = await run.result
    expect(result.structured).toEqual({ answer: 12 })
    const request = adapter.requests[0]!
    expect(toolNames(request)).toEqual([RUN_CODE_NAME])
    expect(request.system).toContain('interface ToolArgsMap')
    expect(request.system).toContain('interface ToolOutputMap')
    expect(request.system).toContain('recorded: true;')
    expect(request.system).toContain('Promise<ToolOutputMap[K]>')
    expect(request.system).toContain(STRUCTURED_OUTPUT_INSTRUCTION)
    await run.dispose()
  })

  it('discards a nested capture when the enclosing run_code execution fails', async () => {
    const { ctx, parent, adapter } = await setup([
      toolCallResponse('c1', RUN_CODE_NAME, { code: 'await tools.structured_output({ answer: 12 }); throw new Error("boom")', description: 'Capture then fail the program' }),
      textResponse('outer code failed'),
    ], {
      toolMode: 'code',
      codeRun: async (request) => {
        const capture = request.bindings.at(0)?.functions[STRUCTURED_OUTPUT_TOOL]
        if (!capture) throw new Error('structured_output binding missing')
        await capture({ answer: 12 })
        return {
          logs: [],
          error: { kind: 'runtime', message: 'boom after capture' },
        } as never
      },
    })
    const run = await ctx.subagents.start('spawn', structuredRequest(parent))

    const result = await run.result
    expect(result.structured).toBeUndefined()
    expect(result.stopReason).toBe('error')
    expect(adapter.requests).toHaveLength(2)
    const child = ctx.agents.get(run.id)!
    const outer = child.session.events.find(event =>
      event.type === 'tool/result' && event.data.message.source.callId === CallId('c1'))
    expect(outer?.type === 'tool/result' && outer.data.message.content[0].isError).toBe(true)
    await run.dispose()
  })

  it('discards a nested capture when post-policy blocks the enclosing run_code result', async () => {
    const { ctx, parent, adapter } = await setup([
      toolCallResponse('c1', RUN_CODE_NAME, { code: 'return await tools.structured_output({ answer: 12 })', description: 'Capture the structured answer' }),
      textResponse('outer code was blocked'),
    ], {
      toolMode: 'code',
      codeRun: async (request) => {
        const capture = request.bindings.at(0)?.functions[STRUCTURED_OUTPUT_TOOL]
        if (!capture) throw new Error('structured_output binding missing')
        await capture({ answer: 12 })
        return { logs: [], value: 'captured' }
      },
    })
    ctx.on('tools/post-execute', (exec, _result, next) => exec.name === RUN_CODE_NAME
      ? Promise.resolve({ kind: 'block' as const, feedback: [{ type: 'text' as const, text: 'outer blocked' }] })
      : next())
    const run = await ctx.subagents.start('spawn', structuredRequest(parent))

    const result = await run.result
    expect(result.structured).toBeUndefined()
    expect(result.stopReason).toBe('error')
    expect(adapter.requests).toHaveLength(2)
    await run.dispose()
  })

  it('the instruction rides ONLY structured requests: appended for the child, absent for a plain agent', async () => {
    const { ctx, parent, adapter } = await setup([
      textResponse('parent answer'),
      toolCallResponse('c1', STRUCTURED_OUTPUT_TOOL, { answer: 1 }),
    ])
    parent.followup(createUserMessage({ content: [{ type: 'text', text: 'hello' }], source: { kind: 'user' } }))
    await parent.whenIdle()
    expect(adapter.requests[0]!.system ?? '').not.toContain(STRUCTURED_OUTPUT_INSTRUCTION)
    const run = await ctx.subagents.start('spawn', structuredRequest(parent))
    await run.result
    // The loop always assembles a base prompt (the harness identity section),
    // so the instruction APPENDS — never replaces.
    const childSystem = adapter.requests.at(-1)!.system!
    expect(childSystem.endsWith(STRUCTURED_OUTPUT_INSTRUCTION)).toBe(true)
    expect(childSystem.length).toBeGreaterThan(STRUCTURED_OUTPUT_INSTRUCTION.length)
    await run.dispose()
  })

  describe('scoped registration (each child owns its capture tool)', () => {
    it('a plain agent never sees the tool: nothing is registered globally at all', async () => {
      const { ctx, parent, adapter } = await setup([textResponse('parent answer')])
      parent.followup(createUserMessage({ content: [{ type: 'text', text: 'hello' }], source: { kind: 'user' } }))
      await parent.whenIdle()
      // Scoped registration: the global view has no capture tool, ever.
      expect(ctx.tools.get(STRUCTURED_OUTPUT_TOOL)).toBeUndefined()
      expect(toolNames(adapter.requests[0]!)).not.toContain(STRUCTURED_OUTPUT_TOOL)
    })

    it('a structured child sees structured_output with ITS schema; a plain agent never sees the tool', async () => {
      const { ctx, parent, adapter } = await setup([
        // Parent turn (a plain agent): must NOT see the tool.
        textResponse('parent answer'),
        // Child turn: must see it, with the run's schema.
        toolCallResponse('c1', STRUCTURED_OUTPUT_TOOL, { answer: 42 }),
      ])
      parent.followup(createUserMessage({ content: [{ type: 'text', text: 'hello' }], source: { kind: 'user' } }))
      await parent.whenIdle()
      expect(toolNames(adapter.requests[0]!)).not.toContain(STRUCTURED_OUTPUT_TOOL)

      const run = await ctx.subagents.start('spawn', structuredRequest(parent))
      await run.result
      const childRequest = adapter.requests[1]!
      expect(toolNames(childRequest)).toContain(STRUCTURED_OUTPUT_TOOL)
      const entry = childRequest.tools!.find(tool => tool.name === STRUCTURED_OUTPUT_TOOL)!
      expect(entry.parameters).toEqual(SCHEMA)
      await run.dispose()
    })

    it('two concurrent structured children each see their OWN schema', async () => {
      const otherSchema: ObjectJsonSchema = {
        type: 'object',
        properties: { verdict: { type: 'string', enum: ['real', 'bogus'] } },
        required: ['verdict'],
      }
      const { ctx, parent, adapter } = await setup([
        (options: GenerateOptions) => {
          // Answer with whatever schema this child was given — proves each
          // request carried the right one regardless of scheduling order.
          const entry = options.tools!.find(tool => tool.name === STRUCTURED_OUTPUT_TOOL)!
          const args = 'verdict' in (entry.parameters.properties as Record<string, unknown>)
            ? { verdict: 'real' }
            : { answer: 1 }
          return toolCallResponse('c1', STRUCTURED_OUTPUT_TOOL, args)
        },
        (options: GenerateOptions) => {
          const entry = options.tools!.find(tool => tool.name === STRUCTURED_OUTPUT_TOOL)!
          const args = 'verdict' in (entry.parameters.properties as Record<string, unknown>)
            ? { verdict: 'real' }
            : { answer: 1 }
          return toolCallResponse('c2', STRUCTURED_OUTPUT_TOOL, args)
        },
      ])
      const runA = await ctx.subagents.start('spawn', structuredRequest(parent))
      const runB = await ctx.subagents.start('spawn', structuredRequest(parent, { outputSchema: otherSchema }))
      const [a, b] = await Promise.all([runA.result, runB.result])
      expect(a.structured).toEqual({ answer: 1 })
      expect(b.structured).toEqual({ verdict: 'real' })
      const schemas = adapter.requests.map(request =>
        request.tools!.find(tool => tool.name === STRUCTURED_OUTPUT_TOOL)!.parameters)
      expect(schemas).toContainEqual(SCHEMA)
      expect(schemas).toContainEqual(otherSchema)
      await runA.dispose()
      await runB.dispose()
    })

    it('places the capture tool and instruction in their canonical orders', async () => {
      const { ctx, parent, adapter } = await setup([
        toolCallResponse('c1', STRUCTURED_OUTPUT_TOOL, { answer: 7 }),
      ])
      // A global tool sorts lexicographically after structured_output, while a
      // global section above the 190 band follows the capture instruction.
      ctx.tools.register(defineContentToolFixture({
        name: 'zz_probe',
        description: 'probe',
        parameters: {},
        execute: () => Promise.resolve([{ type: 'text', text: 'x' }]),
      }))
      ctx.systemPrompt.section({ name: 'after-band', order: 200, text: 'AFTER-BAND' })
      const run = await ctx.subagents.start('spawn', structuredRequest(parent))
      await run.result
      const request = adapter.requests[0]!
      const names = toolNames(request)
      expect(names.indexOf(STRUCTURED_OUTPUT_TOOL)).toBeGreaterThanOrEqual(0)
      expect(names.indexOf(STRUCTURED_OUTPUT_TOOL)).toBeLessThan(names.indexOf('zz_probe'))
      const system = request.system ?? ''
      const instructionAt = system.indexOf(STRUCTURED_OUTPUT_INSTRUCTION)
      expect(instructionAt).toBeGreaterThanOrEqual(0)
      expect(system.indexOf('AFTER-BAND')).toBeGreaterThan(instructionAt)
      await run.dispose()
    })

    it('a non-structured agent request keeps tools ABSENT when it had none (no tools: [] materialized)', async () => {
      const { parent, adapter } = await setup([textResponse('plain')])
      parent.followup(createUserMessage({ content: [{ type: 'text', text: 'q' }], source: { kind: 'user' } }))
      await parent.whenIdle()
      const request = adapter.requests[0]!
      expect(request.tools).toBeUndefined()
      await new Promise(resolve => setTimeout(resolve, 0))
    })

    it('registrations ride the child fiber: disposing the run removes them; a provider reload mid-run cannot', async () => {
      const { ctx, parent, disposeProvider } = await setup([
        toolCallResponse('c1', STRUCTURED_OUTPUT_TOOL, { answer: 4 }),
      ])
      expect(ctx.tools.get(STRUCTURED_OUTPUT_TOOL)).toBeUndefined()
      const run = await ctx.subagents.start('spawn', structuredRequest(parent))
      // A backend hot-reload mid-run must not unregister the capture tool out
      // from under the live child: the registration rides the CHILD's fiber.
      disposeProvider()
      const result = await run.result
      expect(result.structured).toEqual({ answer: 4 })
      const child = ctx.agents.get(run.id)!
      expect(ctx.tools.get(STRUCTURED_OUTPUT_TOOL, child)).toBeDefined()
      await run.dispose()
      // Child disposed ⇒ its scoped registrations are gone.
      expect(ctx.tools.get(STRUCTURED_OUTPUT_TOOL, child)).toBeUndefined()
    })
  })

  it('a structured_output call from an agent WITHOUT a structured run is UNKNOWN_TOOL (the tool does not exist for it)', async () => {
    const { ctx, parent } = await setup([])
    const result = await ctx.tools.execute({
      signal: testToolSignal,
      callId: 'x' as never,
      name: STRUCTURED_OUTPUT_TOOL,
      arguments: { answer: 1 },
      agent: parent,
    })
    expect(result.isError).toBe(true)
    expect(result.error?.info?.code).toBe('UNKNOWN_TOOL')
  })

  it('a structured_output call with NO calling agent at all is UNKNOWN_TOOL', async () => {
    const { ctx } = await setup([])
    const result = await ctx.tools.execute({
      signal: testToolSignal,
      callId: 'x' as never,
      name: STRUCTURED_OUTPUT_TOOL,
      arguments: { answer: 1 },
    })
    expect(result.isError).toBe(true)
    expect(result.error?.info?.code).toBe('UNKNOWN_TOOL')
  })

  it('a failed execution stage is discarded and never promoted by a later call', async () => {
    const { ctx, parent } = await setup([
      toolCallResponse('c1', STRUCTURED_OUTPUT_TOOL, { answer: 1 }),
    ])
    const run = await ctx.subagents.start('spawn', structuredRequest(parent))
    // A prepended post-execute listener blocks the first capture without
    // delegating. The final-result notification discards that execution's
    // stage when it observes the error.
    let blocks = 1
    ctx.on('tools/post-execute', (exec, _result, next) => {
      if (exec.name === STRUCTURED_OUTPUT_TOOL && blocks > 0) {
        blocks -= 1
        return Promise.resolve({ kind: 'block' as const, feedback: [{ type: 'text' as const, text: 'rejected' }] })
      }
      return next()
    }, { prepend: true })
    const result = await run.result
    const child = ctx.agents.get(run.id)!
    // The blocked capture must NOT surface as structured success…
    expect(result.stopReason).toBe('error')
    expect(result.structured).toBeUndefined()
    // …and a LATER invalid call (its own body staged nothing) must not
    // resurrect c1's discarded value: drive the pipeline directly.
    const invalid = await ctx.tools.execute({
      signal: testToolSignal,
      callId: 'c2' as never,
      name: STRUCTURED_OUTPUT_TOOL,
      arguments: { answer: 'not-a-number' },
      agent: child,
    })
    expect(invalid.isError).toBe(true)
    // A fresh valid call still captures ITS OWN value.
    const valid = await ctx.tools.execute({
      signal: testToolSignal,
      callId: 'c3' as never,
      name: STRUCTURED_OUTPUT_TOOL,
      arguments: { answer: 9 },
      agent: child,
    })
    expect(valid.isError).toBeFalsy()
    await run.dispose()
  })

  it('reusing a failed execution\'s call id never promotes its discarded stage', async () => {
    const { ctx, parent } = await setup([
      toolCallResponse('c1', STRUCTURED_OUTPUT_TOOL, { answer: 1 }),
    ])
    const run = await ctx.subagents.start('spawn', structuredRequest(parent))
    // Block the first capture after its body stages a value. Its final error
    // discards that execution's stage.
    let blocks = 1
    ctx.on('tools/post-execute', (exec, _result, next) => {
      if (exec.name === STRUCTURED_OUTPUT_TOOL && blocks > 0) {
        blocks -= 1
        return Promise.resolve({ kind: 'block' as const, feedback: [{ type: 'text' as const, text: 'rejected' }] })
      }
      return next()
    }, { prepend: true })
    await run.result
    const child = ctx.agents.get(run.id)!
    // A SECOND capture call with the SAME call id whose body never stages
    // (invalid args throw before the stage): the discarded value must not ride
    // its acceptance.
    const reused = await ctx.tools.execute({
      signal: testToolSignal,
      callId: 'c1' as never,
      name: STRUCTURED_OUTPUT_TOOL,
      arguments: { answer: 'not-a-number' },
      agent: child,
    })
    expect(reused.isError).toBe(true)
    // Nothing was ever committed: a fresh valid call is still required.
    const valid = await ctx.tools.execute({
      signal: testToolSignal,
      callId: 'c1' as never,
      name: STRUCTURED_OUTPUT_TOOL,
      arguments: { answer: 5 },
      agent: child,
    })
    expect(valid.isError).toBeFalsy()
    await run.dispose()
  })

  it('a pre-execute deny with call-id reuse cannot promote another execution\'s stage', async () => {
    const { ctx, parent } = await setup([
      toolCallResponse('c1', STRUCTURED_OUTPUT_TOOL, { answer: 1 }),
    ])
    const run = await ctx.subagents.start('spawn', structuredRequest(parent))
    // Discard the first capture's stage via a final post-execute block.
    let blocks = 1
    ctx.on('tools/post-execute', (exec, _result, next) => {
      if (exec.name === STRUCTURED_OUTPUT_TOOL && blocks > 0) {
        blocks -= 1
        return Promise.resolve({ kind: 'block' as const, feedback: [{ type: 'text' as const, text: 'rejected' }] })
      }
      return next()
    }, { prepend: true })
    await run.result
    const child = ctx.agents.get(run.id)!
    // A prepended pre-execute deny skips the body, while the denied call still
    // reaches the final notification with the same adapter-minted call id.
    const offDeny = ctx.on('tools/pre-execute', (exec) => {
      if (exec.name === STRUCTURED_OUTPUT_TOOL) {
        return Promise.resolve({ kind: 'deny' as const, reason: 'outer veto' })
      }
      return undefined as never
    }, { prepend: true })
    const denied = await ctx.tools.execute({
      signal: testToolSignal,
      callId: 'c1' as never,
      name: STRUCTURED_OUTPUT_TOOL,
      arguments: { answer: 2 },
      agent: child,
    })
    expect(denied.isError).toBe(true)
    offDeny()
    // The discarded value was never promoted: a fresh valid call is required
    // (and succeeds, proving the runtime is not wedged).
    const valid = await ctx.tools.execute({
      signal: testToolSignal,
      callId: 'c1' as never,
      name: STRUCTURED_OUTPUT_TOOL,
      arguments: { answer: 5 },
      agent: child,
    })
    expect(valid.isError).toBeFalsy()
    await run.dispose()
  })
})