Merge pull request #4074 from code-yeongyu/fix/delegate-task-spawn

fix(delegate-task): start child prompts reliably

src/agents/agent-builder.test.ts

@@ -1,16 +1,15 @@
-import { describe, test, expect } from "bun:test"
+import { describe, expect, test } from "bun:test"
 import { buildAgent } from "./agent-builder"
 import type { AgentFactory } from "./types"
 
 describe("#given an agent factory with mode", () => {
-  const mockFactory = ((model: string) => ({
+  const mockFactory: AgentFactory = Object.assign((model: string) => ({
     name: "test-agent",
     description: "Test",
     instructions: "test",
     model,
     temperature: 0.1,
-  })) as AgentFactory
-  mockFactory.mode = "subagent"
+  }), { mode: "subagent" as const })
 
   test("#when building agent from factory", () => {
     const agent = buildAgent(mockFactory, "test-model")
@@ -19,14 +18,13 @@ describe("#given an agent factory with mode", () => {
 })
 
 describe("#given an agent factory with mode=primary", () => {
-  const mockFactory = ((model: string) => ({
+  const mockFactory: AgentFactory = Object.assign((model: string) => ({
     name: "primary-agent",
     description: "Primary Test",
     instructions: "test",
     model,
     temperature: 0.1,
-  })) as AgentFactory
-  mockFactory.mode = "primary"
+  }), { mode: "primary" as const })
 
   test("#when building agent from factory", () => {
     const agent = buildAgent(mockFactory, "test-model")
@@ -50,15 +48,14 @@ describe("#given an agent config object without mode", () => {
 })
 
 describe("#given an agent factory with mode but config already has mode", () => {
-  const mockFactory = ((model: string) => ({
+  const mockFactory: AgentFactory = Object.assign((model: string) => ({
     name: "override-agent",
     description: "Override Test",
     instructions: "test",
     model,
     temperature: 0.1,
-    mode: "all",
-  })) as AgentFactory
-  mockFactory.mode = "subagent"
+    mode: "all" as const,
+  }), { mode: "subagent" as const })
 
   test("#when building agent from factory", () => {
     const agent = buildAgent(mockFactory, "test-model")

src/agents/builtin-agents/available-skills.test.ts

@@ -2,10 +2,12 @@ import { describe, expect, test } from "bun:test"
 
 import { buildAvailableSkills } from "./available-skills"
 
+type DiscoveredSkills = Parameters<typeof buildAvailableSkills>[0]
+
 describe("buildAvailableSkills", () => {
   test("includes team-mode when team mode is enabled", () => {
     // given
-    const discoveredSkills = []
+    const discoveredSkills: DiscoveredSkills = []
 
     // when
     const availableSkills = buildAvailableSkills(discoveredSkills, undefined, undefined, true)
@@ -16,7 +18,7 @@ describe("buildAvailableSkills", () => {
 
   test("excludes team-mode when team mode is disabled", () => {
     // given
-    const discoveredSkills = []
+    const discoveredSkills: DiscoveredSkills = []
 
     // when
     const availableSkills = buildAvailableSkills(discoveredSkills, undefined, undefined, false)

src/features/background-agent/fallback-retry-handler.test.ts

@@ -1,10 +1,12 @@
 import { afterAll, beforeEach, describe, expect, mock, test } from "bun:test"
 import { tryFallbackRetry, type FallbackRetryHandlerDeps } from "./fallback-retry-handler"
 import type { FallbackEntry } from "../../shared/model-requirements"
+import type { ProviderModelsCache } from "../../shared/connected-providers-cache"
+import { QUESTION_DENIED_SESSION_PERMISSION } from "../../shared/question-denied-session-permission"
 
 const sharedLogMock = mock(() => {})
 const readConnectedProvidersCacheMock = mock(() => null)
-const readProviderModelsCacheMock = mock((): { connected: string[] } | null => null)
+const readProviderModelsCacheMock = mock((): ProviderModelsCache | null => null)
 const shouldRetryErrorMock = mock(() => true)
 const getNextFallbackMock = mock((chain: FallbackEntry[], attempt: number) => chain[attempt])
 const hasMoreFallbacksMock = mock((chain: FallbackEntry[], attempt: number) => attempt < chain.length)
@@ -258,6 +260,20 @@ describe("tryFallbackRetry", () => {
       expect(retryInput?.onSessionCreated).toBe(onSessionCreated)
     })
 
+    test("preserves delegated launch context in retry input", async () => {
+      const args = createDefaultArgs({
+        skillContent: "delegated skill system",
+        sessionPermission: QUESTION_DENIED_SESSION_PERMISSION,
+      })
+
+      await tryFallbackRetry(args)
+
+      const key = `${args.task.model!.providerID}/${args.task.model!.modelID}`
+      const retryInput = args.queuesByKey.get(key)?.[0]?.input
+      expect(retryInput?.skillContent).toBe("delegated skill system")
+      expect(retryInput?.sessionPermission).toEqual(QUESTION_DENIED_SESSION_PERMISSION)
+    })
+
     test("finalizes the failed attempt, creates a new pending attempt, and enqueues its explicit attemptID", async () => {
       const args = createDefaultArgs({
         status: "running",
@@ -416,7 +432,11 @@ describe("tryFallbackRetry", () => {
 
   describe("#given disconnected fallback providers with connected preferred provider", () => {
     test("keeps fallback entry and selects connected preferred provider", async () => {
-      readProviderModelsCacheMock.mockReturnValueOnce({ connected: ["provider-a"] })
+      readProviderModelsCacheMock.mockReturnValueOnce({
+        connected: ["provider-a"],
+        models: {},
+        updatedAt: new Date("2026-05-16T00:00:00.000Z").toISOString(),
+      })
       selectFallbackProviderMock.mockImplementationOnce(
         (_providers: string[], preferredProviderID?: string) => preferredProviderID ?? "provider-b",
       )

src/features/background-agent/fallback-retry-handler.ts

@@ -197,6 +197,8 @@ export async function tryFallbackRetry(args: {
     teamRunId: task.teamRunId,
     model: nextModel,
     fallbackChain: task.fallbackChain,
+    skillContent: task.skillContent,
+    sessionPermission: task.sessionPermission,
     category: task.category,
     isUnstableAgent: task.isUnstableAgent,
     onSessionCreated: task.onSessionCreated,

src/features/background-agent/manager.test.ts

@@ -1,21 +1,32 @@
-declare const require: (name: string) => any
-const { describe, test, expect, beforeEach, afterEach, afterAll, spyOn, mock } = require("bun:test")
+import { tmpdir } from "node:os"
+import { describe, test, expect, beforeEach, afterEach, afterAll, spyOn, mock } from "bun:test"
+import type { PluginInput } from "@opencode-ai/plugin"
+import * as sharedModule from "../../shared"
+import {
+  clearAllDelegatedChildSessionBootstrap,
+  getDelegatedChildSessionBootstrap,
+} from "../../shared/delegated-child-session-bootstrap"
+import { promptAsyncAfterSessionIdle } from "../../shared/prompt-async-gate"
+import { clearSessionPromptParams, getSessionPromptParams } from "../../shared/session-prompt-params-state"
+import {
+  getSessionAgent,
+  registerAgentName,
+  _resetForTesting as resetClaudeCodeSessionState,
+  subagentSessions,
+} from "../claude-code-session-state"
+import { _resetTaskToastManagerForTesting, initTaskToastManager } from "../task-toast-manager/manager"
+import type { ConcurrencyManager } from "./concurrency"
+import { MIN_IDLE_TIME_MS } from "./constants"
+import { BackgroundManager } from "./manager"
+import { _resetForTesting as resetProcessCleanupState } from "./process-cleanup"
+import { clearBackgroundTaskRegistryForTesting } from "./task-registry"
+import type { BackgroundTask, ResumeInput } from "./types"
 
 afterAll(() => { mock.restore() })
 
-import { getSessionPromptParams, clearSessionPromptParams } from "../../shared/session-prompt-params-state"
-import { tmpdir } from "node:os"
-import type { PluginInput } from "@opencode-ai/plugin"
-import * as sharedModule from "../../shared"
-import { _resetForTesting as resetClaudeCodeSessionState, registerAgentName, subagentSessions } from "../claude-code-session-state"
-import type { BackgroundTask, ResumeInput } from "./types"
-import { MIN_IDLE_TIME_MS } from "./constants"
-import { BackgroundManager } from "./manager"
-import { ConcurrencyManager } from "./concurrency"
-import { promptAsyncAfterSessionIdle } from "../../shared/prompt-async-gate"
-import { initTaskToastManager, _resetTaskToastManagerForTesting } from "../task-toast-manager/manager"
-import { _resetForTesting as resetProcessCleanupState } from "./process-cleanup"
-
+afterEach(() => {
+  clearBackgroundTaskRegistryForTesting()
+})
 
 const TASK_TTL_MS = 30 * 60 * 1000
 type PendingParentWakeForTest = {
@@ -186,6 +197,30 @@ function cast<T>(value: unknown): T {
   return value as T
 }
 
+async function expectRejectsWithMessage(promise: Promise<unknown>, expectedMessage: string): Promise<void> {
+  await promise.then(
+    () => {
+      throw new Error(`Expected promise to reject with ${expectedMessage}`)
+    },
+    (error: unknown) => {
+      expect(String(error)).toContain(expectedMessage)
+    },
+  )
+}
+
+async function expectResolvesDefined(promise: Promise<unknown>): Promise<void> {
+  const result = await promise
+  expect(result).toBeDefined()
+}
+
+async function expectResolvesMatchObject<TActual extends object>(
+  promise: Promise<TActual>,
+  expected: Partial<TActual>,
+): Promise<void> {
+  const result = await promise
+  expect(result).toMatchObject(expected)
+}
+
 function createPluginInput(client: unknown, directory = tmpdir()): PluginInput {
   return cast<PluginInput>({ client, directory })
 }
@@ -458,6 +493,77 @@ describe("BackgroundManager session.error fallback hydration", () => {
   })
 })
 
+describe("BackgroundManager delegated child-session bootstrap", () => {
+  test("registers launch bootstrap before first prompt and clears it after completion", async () => {
+    //#given
+    clearAllDelegatedChildSessionBootstrap()
+    const observedBootstrapPrompts: string[] = []
+    const client = {
+      session: {
+        get: async () => ({ data: { directory: tmpdir() } }),
+        create: async () => ({ data: { id: "ses_background_bootstrap" } }),
+        promptAsync: async () => {
+          const bootstrap = getDelegatedChildSessionBootstrap("ses_background_bootstrap")
+          observedBootstrapPrompts.push(bootstrap?.retryParts[0]?.text ?? "")
+          return {}
+        },
+        abort: async () => ({}),
+      },
+    }
+    const manager = new BackgroundManager({ pluginContext: createPluginInput(client) })
+    stubNotifyParentSession(manager)
+    const task = createMockTask({
+      id: "bg_bootstrap",
+      parentSessionId: "parent-session",
+      status: "pending",
+      queuedAt: new Date(),
+      prompt: "background bootstrap prompt",
+      agent: "sisyphus-junior",
+      skillContent: "background delegated skill system",
+      category: "quick",
+      model: { providerID: "anthropic", modelID: "claude-haiku-4-5" },
+      fallbackChain: [{ model: "gpt-5.4", providers: ["openai"], variant: "high" }],
+    })
+    getTaskMap(manager).set(task.id, task)
+    const input = {
+      description: task.description,
+      prompt: task.prompt,
+      agent: task.agent,
+      parentSessionId: task.parentSessionId,
+      parentMessageId: task.parentMessageId,
+      parentModel: task.parentModel,
+      parentAgent: task.parentAgent,
+      parentTools: task.parentTools,
+      model: task.model,
+      fallbackChain: task.fallbackChain,
+      skillContent: task.skillContent,
+      category: task.category,
+    }
+
+    try {
+      //#when
+      await (cast<{ startTask: (item: { task: BackgroundTask; input: typeof input }) => Promise<void> }>(manager))
+        .startTask({ task, input })
+      await flushBackgroundNotifications()
+
+      //#then
+      expect(observedBootstrapPrompts[0]).toContain("background bootstrap prompt")
+      const bootstrap = getDelegatedChildSessionBootstrap("ses_background_bootstrap")
+      expect(bootstrap?.system).toBe("background delegated skill system")
+      expect(bootstrap?.tools?.question).toBe(false)
+      expect(bootstrap?.tools?.task).toBe(false)
+      expect(getDelegatedChildSessionBootstrap("ses_background_bootstrap")).toBeDefined()
+
+      const completed = await tryCompleteTaskForTest(manager, task)
+      expect(completed).toBe(true)
+      expect(getDelegatedChildSessionBootstrap("ses_background_bootstrap")).toBeUndefined()
+    } finally {
+      manager.shutdown()
+      clearAllDelegatedChildSessionBootstrap()
+    }
+  })
+})
+
 describe("BackgroundManager prompt rejection fallback routing", () => {
   test("routes launch-time prompt rejections into tryFallbackRetry before marking interrupt", async () => {
     //#given
@@ -635,7 +741,13 @@ describe("BackgroundManager retry observability", () => {
 
     //#then
     expect(queuePendingParentWake).toHaveBeenCalledTimes(1)
-    const [sessionID, notification, promptContext, shouldReply] = queuePendingParentWake.mock.calls[0]
+    const retryingCall = cast<Array<[string, string, Record<string, unknown>, boolean]>>(
+      queuePendingParentWake.mock.calls,
+    )[0]
+    if (!retryingCall) {
+      throw new Error("Expected retrying parent wake call")
+    }
+    const [sessionID, notification, promptContext, shouldReply] = retryingCall
     expect(sessionID).toBe("parent-session")
     expect(promptContext).toEqual({})
     expect(shouldReply).toBe(false)
@@ -2767,7 +2879,7 @@ describe("BackgroundManager - Non-blocking Queue Integration", () => {
       const result = manager.launch(input)
 
       // then
-      await expect(result).rejects.toThrow("Agent parameter is required after sanitization")
+      await expectRejectsWithMessage(result, "Agent parameter is required after sanitization")
     })
 
     test("should initialize attempt state for a newly launched task", async () => {
@@ -3089,7 +3201,7 @@ describe("BackgroundManager - Non-blocking Queue Integration", () => {
       const result = manager.launch(input)
 
       // then
-      await expect(result).rejects.toThrow("background_task.maxDepth=3")
+      await expectRejectsWithMessage(result, "background_task.maxDepth=3")
     })
 
     test("allows multiple descendants without a root spawn cap", async () => {
@@ -3118,7 +3230,7 @@ describe("BackgroundManager - Non-blocking Queue Integration", () => {
       const result = manager.launch(input)
 
       // then
-      await expect(result).resolves.toBeDefined()
+      await expectResolvesDefined(result)
     })
 
     test("allows spawn assertions after reserveSubagentSpawn without a root spawn cap", async () => {
@@ -3139,7 +3251,7 @@ describe("BackgroundManager - Non-blocking Queue Integration", () => {
       const result = manager.assertCanSpawn("session-root")
 
       // then
-      await expect(result).resolves.toMatchObject({
+      await expectResolvesMatchObject(result, {
         rootSessionID: "session-root",
         childDepth: 1,
       })
@@ -3172,7 +3284,7 @@ describe("BackgroundManager - Non-blocking Queue Integration", () => {
       const result = manager.launch(input)
 
       // then
-      await expect(result).rejects.toThrow("background_task.maxDepth cannot be enforced safely")
+      await expectRejectsWithMessage(result, "background_task.maxDepth cannot be enforced safely")
     })
 
     test("allows replacement launch when a queued task is cancelled before session starts", async () => {
@@ -3672,7 +3784,7 @@ describe("BackgroundManager - Non-blocking Queue Integration", () => {
       // Complete via internal method (session.status events go through the poller, not handleEvent)
       await tryCompleteTaskForTest(manager, internalTask)
 
-      await expect(manager.launch(input)).resolves.toBeDefined()
+      await expectResolvesDefined(manager.launch(input))
     })
 
     test("allows relaunch after running task is cancelled", async () => {
@@ -3701,7 +3813,7 @@ describe("BackgroundManager - Non-blocking Queue Integration", () => {
 
       await manager.cancelTask(task.id)
 
-      await expect(manager.launch(input)).resolves.toBeDefined()
+      await expectResolvesDefined(manager.launch(input))
     })
 
     test("allows relaunch after task errors", async () => {
@@ -3734,7 +3846,7 @@ describe("BackgroundManager - Non-blocking Queue Integration", () => {
       })
       await new Promise((resolve) => setTimeout(resolve, 100))
 
-      await expect(manager.launch(input)).resolves.toBeDefined()
+      await expectResolvesDefined(manager.launch(input))
     })
 
     test("allows repeated relaunch after pending tasks are cancelled", async () => {
@@ -3762,8 +3874,8 @@ describe("BackgroundManager - Non-blocking Queue Integration", () => {
       await manager.cancelTask(task1.id)
       await manager.cancelTask(task2.id)
 
-      await expect(manager.launch(input)).resolves.toBeDefined()
-      await expect(manager.launch(input)).resolves.toBeDefined()
+      await expectResolvesDefined(manager.launch(input))
+      await expectResolvesDefined(manager.launch(input))
     })
   })
 
@@ -4977,10 +5089,12 @@ describe("BackgroundManager.handleEvent - session.error", () => {
 
   const mockVerifySessionExists = (manager: BackgroundManager, sessionExists: boolean): void => {
     verifySessionExistsSpy?.mockRestore()
-    verifySessionExistsSpy = spyOn(
+    const spy = spyOn(
       cast<{ verifySessionExists: (sessionID: string) => Promise<boolean> }>(manager),
       "verifySessionExists",
-    ).mockResolvedValue(sessionExists)
+    )
+    spy.mockImplementation(async () => sessionExists)
+    verifySessionExistsSpy = spy
   }
 
   const stubProcessKey = (manager: BackgroundManager) => {
@@ -6721,6 +6835,157 @@ describe("BackgroundManager regression fixes - resume and aborted notification",
     manager.shutdown()
   })
 
+  test("should resolve a completed task registered by an earlier plugin manager instance", () => {
+    //#given
+    const firstManager = createBackgroundManager()
+    const secondManager = createBackgroundManager()
+    const task: BackgroundTask = {
+      id: "task-cross-manager-regression",
+      sessionId: "session-cross-manager-regression",
+      parentSessionId: "parent-session",
+      parentMessageId: "msg-1",
+      description: "cross manager regression",
+      prompt: "test",
+      agent: "explore",
+      status: "completed",
+      startedAt: new Date(),
+      completedAt: new Date(),
+    }
+
+    //#when
+    ;(cast<{ addTask: (task: BackgroundTask) => void }>(firstManager)).addTask(task)
+
+    //#then
+    const resolvedTask = secondManager.getTask(task.id)
+    expect(resolvedTask?.sessionId).toBe(task.sessionId)
+
+    firstManager.shutdown()
+    secondManager.shutdown()
+  })
+
+  test("should redact active task prompts resolved from an earlier plugin manager instance", () => {
+    //#given
+    const firstManager = createBackgroundManager()
+    const secondManager = createBackgroundManager()
+    const task: BackgroundTask = {
+      id: "task-cross-manager-active-redaction",
+      parentSessionId: "parent-session",
+      parentMessageId: "msg-1",
+      description: "cross manager active redaction",
+      prompt: "secret prompt",
+      agent: "explore",
+      status: "pending",
+      queuedAt: new Date(),
+    }
+
+    //#when
+    ;(cast<{ addTask: (task: BackgroundTask) => void }>(firstManager)).addTask(task)
+    task.sessionId = "session-cross-manager-active-redaction"
+    task.status = "running"
+    task.startedAt = new Date()
+    task.progress = {
+      lastUpdate: new Date(),
+      toolCalls: 1,
+      countedToolPartIDs: new Set(["part-1"]),
+    }
+
+    //#then
+    const localTask = firstManager.getTask(task.id)
+    const registeredTask = secondManager.getTask(task.id)
+    expect(localTask?.prompt).toBe("secret prompt")
+    expect(registeredTask?.sessionId).toBe(task.sessionId)
+    expect(registeredTask?.prompt).toBe("[redacted]")
+    expect(registeredTask?.progress?.countedToolPartIDs).toEqual(new Set(["part-1"]))
+
+    firstManager.shutdown()
+    secondManager.shutdown()
+  })
+
+  test("should resolve archived completed task from an earlier plugin manager instance", () => {
+    //#given
+    const firstManager = createBackgroundManager()
+    const secondManager = createBackgroundManager()
+    const task: BackgroundTask = {
+      id: "task-cross-manager-archive-regression",
+      sessionId: "session-cross-manager-archive-regression",
+      parentSessionId: "parent-session",
+      parentMessageId: "msg-1",
+      description: "cross manager archive regression",
+      prompt: "sensitive prompt",
+      agent: "explore",
+      status: "completed",
+      startedAt: new Date(),
+      completedAt: new Date(),
+    }
+    getTaskMap(firstManager).set(task.id, task)
+
+    //#when
+    ;(cast<{ removeTask: (task: BackgroundTask) => void }>(firstManager)).removeTask(task)
+
+    //#then
+    const resolvedTask = secondManager.getTask(task.id)
+    expect(resolvedTask?.sessionId).toBe(task.sessionId)
+    expect(resolvedTask?.prompt).toBe("[redacted]")
+
+    firstManager.shutdown()
+    secondManager.shutdown()
+  })
+
+  test("should archive terminal registry tasks during earlier manager shutdown", async () => {
+    //#given
+    const firstManager = createBackgroundManager()
+    const secondManager = createBackgroundManager()
+    const task: BackgroundTask = {
+      id: "task-shutdown-archive-regression",
+      sessionId: "session-shutdown-archive-regression",
+      parentSessionId: "parent-session",
+      parentMessageId: "msg-1",
+      description: "shutdown archive regression",
+      prompt: "sensitive shutdown prompt",
+      agent: "explore",
+      status: "completed",
+      startedAt: new Date(),
+      completedAt: new Date(),
+    }
+    ;(cast<{ addTask: (task: BackgroundTask) => void }>(firstManager)).addTask(task)
+
+    //#when
+    await firstManager.shutdown()
+
+    //#then
+    const resolvedTask = secondManager.getTask(task.id)
+    expect(resolvedTask?.sessionId).toBe(task.sessionId)
+    expect(resolvedTask?.prompt).toBe("[redacted]")
+
+    await secondManager.shutdown()
+  })
+
+  test("should forget active registry tasks during earlier manager shutdown", async () => {
+    //#given
+    const firstManager = createBackgroundManager()
+    const secondManager = createBackgroundManager()
+    const task: BackgroundTask = {
+      id: "task-shutdown-active-regression",
+      sessionId: "session-shutdown-active-regression",
+      parentSessionId: "parent-session",
+      parentMessageId: "msg-1",
+      description: "shutdown active regression",
+      prompt: "test",
+      agent: "explore",
+      status: "running",
+      startedAt: new Date(),
+    }
+    ;(cast<{ addTask: (task: BackgroundTask) => void }>(firstManager)).addTask(task)
+
+    //#when
+    await firstManager.shutdown()
+
+    //#then
+    expect(secondManager.getTask(task.id)).toBeUndefined()
+
+    await secondManager.shutdown()
+  })
+
   test("should cap completed task archive size at 100 entries", () => {
     //#given
     const manager = createBackgroundManager()
@@ -6848,6 +7113,62 @@ describe("BackgroundManager - tool permission spread order", () => {
     manager.shutdown()
   })
 
+  test("startTask updates tracked session agent when launch falls back to general", async () => {
+    //#given
+    const promptCalls: Array<{ path: { id: string }; body: Record<string, unknown> }> = []
+    let promptCallCount = 0
+    const client = {
+      session: {
+        get: async () => ({ data: { directory: "/test/dir" } }),
+        create: async () => ({ data: { id: "session-manager-fallback" } }),
+        promptAsync: async (args: { path: { id: string }; body: Record<string, unknown> }) => {
+          promptCallCount++
+          promptCalls.push(args)
+          if (promptCallCount === 1) {
+            throw new Error("Agent not found: missing-agent")
+          }
+          return {}
+        },
+      },
+    }
+    const manager = new BackgroundManager({ pluginContext: createPluginInput(client) })
+    const task: BackgroundTask = {
+      id: "task-manager-fallback",
+      status: "pending",
+      queuedAt: new Date(),
+      description: "test task",
+      prompt: "test prompt",
+      agent: "missing-agent",
+      parentSessionId: "parent-session",
+      parentMessageId: "parent-message",
+    }
+    const input: import("./types").LaunchInput = {
+      description: task.description,
+      prompt: task.prompt,
+      agent: task.agent,
+      parentSessionId: task.parentSessionId,
+      parentMessageId: task.parentMessageId,
+    }
+
+    try {
+      //#when
+      await (cast<{ startTask: (item: { task: BackgroundTask; input: import("./types").LaunchInput }) => Promise<void> }>(manager))
+        .startTask({ task, input })
+      await new Promise((resolve) => setTimeout(resolve, 50))
+
+      //#then
+      expect(promptCalls).toHaveLength(2)
+      expect(promptCalls[0].body.agent).toBe("missing-agent")
+      expect(promptCalls[1].body.agent).toBe("general")
+      expect(task.agent).toBe("general")
+      expect(getSessionAgent("session-manager-fallback")).toBe("general")
+      expect(getDelegatedChildSessionBootstrap("session-manager-fallback")?.tools?.call_omo_agent).toBe(true)
+    } finally {
+      manager.shutdown()
+      clearAllDelegatedChildSessionBootstrap()
+    }
+  })
+
   test("resume respects explore agent restrictions", async () => {
     //#given
     let capturedTools: Record<string, unknown> | undefined
@@ -6992,6 +7313,7 @@ describe("BackgroundManager.launch - attempt state initialization", () => {
 describe("BackgroundManager attempt lifecycle bindings", () => {
   test("startTask binds the created session to the queued attempt ID and mirrors task projection", async () => {
     //#given
+    resetClaudeCodeSessionState()
     const client = {
       session: {
         get: async () => ({ data: { directory: "/test/dir" } }),
@@ -7064,6 +7386,68 @@ describe("BackgroundManager attempt lifecycle bindings", () => {
       status: "error",
       error: "first attempt failed",
     })
+    expect(getSessionAgent("session-attempt-2")).toBe("sisyphus-junior")
+
+    manager.shutdown()
+  })
+
+  test("startTask clears child session agent state when task is cancelled before launch binding", async () => {
+    //#given
+    resetClaudeCodeSessionState()
+    const sessionID = "session-cancelled-prelaunch"
+    const client = {
+      session: {
+        get: async () => ({ data: { directory: "/test/dir" } }),
+        create: async () => ({ data: { id: sessionID } }),
+        promptAsync: async () => ({}),
+        abort: async () => ({}),
+      },
+    }
+    const manager = new BackgroundManager({ pluginContext: createPluginInput(client) })
+    const task: BackgroundTask = {
+      id: "task-cancel-prelaunch",
+      status: "pending",
+      queuedAt: new Date(),
+      description: "cancel before bind",
+      prompt: "continue",
+      agent: "sisyphus-junior",
+      parentSessionId: "parent-session",
+      parentMessageId: "parent-message",
+      model: { providerID: "anthropic", modelID: "claude-haiku-4.5" },
+      attempts: [
+        {
+          attemptId: "attempt-1",
+          attemptNumber: 1,
+          providerId: "anthropic",
+          modelId: "claude-haiku-4.5",
+          status: "pending",
+        },
+      ],
+      currentAttemptID: "attempt-1",
+      attemptCount: 1,
+    }
+    const input: import("./types").LaunchInput = {
+      description: task.description,
+      prompt: task.prompt,
+      agent: task.agent,
+      parentSessionId: task.parentSessionId,
+      parentMessageId: task.parentMessageId,
+      model: task.model,
+      onSessionCreated: async () => {
+        // simulate parent flipping task to cancelled between create and bind
+        task.status = "cancelled"
+        const internal = cast<{ tasks: Map<string, BackgroundTask> }>(manager)
+        internal.tasks.set(task.id, task)
+      },
+    }
+
+    //#when
+    await (cast<{
+      startTask: (item: { task: BackgroundTask; input: import("./types").LaunchInput; attemptID: string }) => Promise<void>
+    }>(manager)).startTask({ task, input, attemptID: "attempt-1" })
+
+    //#then
+    expect(getSessionAgent(sessionID)).toBeUndefined()
 
     manager.shutdown()
   })

src/features/background-agent/manager.ts

@@ -1,99 +1,107 @@
-
+import { join } from "node:path"
 import type { PluginInput } from "@opencode-ai/plugin"
+import type { BackgroundTaskConfig, TmuxConfig } from "../../config/schema"
+import { setContinuationMarkerSource } from "../../features/run-continuation-state"
 import type { ModelFallbackControllerAccessor } from "../../hooks/model-fallback"
-import { isAgentNotFoundError, FALLBACK_AGENT, buildFallbackBody } from "./spawner"
-import type {
-  BackgroundTask,
-  BackgroundTaskAttempt,
-  LaunchInput,
-  ResumeInput,
-} from "./types"
-import { TaskHistory } from "./task-history"
+import { type PromptAsyncGateResult, promptAsyncAfterSessionIdle } from "../../hooks/shared/prompt-async-gate"
+import { isSessionActive as isOpenCodeSessionActive } from "../../hooks/shared/session-idle-settle"
 import {
-  log,
+  createInternalAgentTextPart,
   getAgentToolRestrictions,
+  log,
+  messagesInDirectory,
   normalizePromptTools,
   normalizeSDKResponse,
-  resolveInheritedPromptTools,
-  createInternalAgentTextPart,
-  messagesInDirectory,
   promptWithRetryInDirectory,
+  resolveInheritedPromptTools,
 } from "../../shared"
+import {
+  clearDelegatedChildSessionBootstrap,
+  registerDelegatedChildSessionBootstrap,
+} from "../../shared/delegated-child-session-bootstrap"
 import { resolveMessageEventSessionID, resolveSessionEventID } from "../../shared/event-session-id"
+import {
+  hasMoreFallbacks,
+  shouldRetryError,
+} from "../../shared/model-error-classifier"
+import { SessionCategoryRegistry } from "../../shared/session-category-registry"
 import { applySessionPromptParams } from "../../shared/session-prompt-params-helpers"
 import { setSessionTools } from "../../shared/session-tools-store"
-import { SessionCategoryRegistry } from "../../shared/session-category-registry"
-import { ConcurrencyManager } from "./concurrency"
-import type { BackgroundTaskConfig, TmuxConfig } from "../../config/schema"
 import { isInsideTmux } from "../../shared/tmux"
-import {
-  shouldRetryError,
-  hasMoreFallbacks,
-} from "../../shared/model-error-classifier"
-import {
-  POLLING_INTERVAL_MS,
-  TASK_CLEANUP_DELAY_MS,
-  TASK_TTL_MS,
-  type QueueItem,
-} from "./constants"
-
-import { subagentSessions } from "../claude-code-session-state"
+import { clearSessionAgent, setSessionAgent, subagentSessions, updateSessionAgent } from "../claude-code-session-state"
+import { MESSAGE_STORAGE } from "../hook-message-injector"
 import { getTaskToastManager } from "../task-toast-manager"
-import { formatDuration } from "./duration-formatter"
-import {
-  buildBackgroundTaskNotificationText,
-  type BackgroundTaskNotificationTask,
-} from "./background-task-notification-template"
-import {
-  isAbortedSessionError,
-  extractErrorName,
-  extractErrorMessage,
-  extractErrorStatusCode,
-  getSessionErrorMessage,
-  isRecord,
-} from "./error-classifier"
-import { tryFallbackRetry } from "./fallback-retry-handler"
+import { abortWithTimeout } from "./abort-with-timeout"
 import {
   bindAttemptSession,
   ensureCurrentAttempt,
-  findAttemptBySession,
   finalizeAttempt,
+  findAttemptBySession,
   getCurrentAttempt,
   startAttempt,
 } from "./attempt-lifecycle"
-import { registerManagerForCleanup, unregisterManagerForCleanup } from "./process-cleanup"
-import { setContinuationMarkerSource } from "../../features/run-continuation-state"
-import { isSessionActive as isOpenCodeSessionActive } from "../../hooks/shared/session-idle-settle"
-import { promptAsyncAfterSessionIdle, type PromptAsyncGateResult } from "../../hooks/shared/prompt-async-gate"
+import {
+  type BackgroundTaskNotificationTask,
+  buildBackgroundTaskNotificationText,
+} from "./background-task-notification-template"
 import {
   findNearestMessageExcludingCompaction,
   resolvePromptContextFromSessionMessages,
 } from "./compaction-aware-message-resolver"
-import { handleSessionIdleBackgroundEvent } from "./session-idle-event-handler"
-import { MESSAGE_STORAGE } from "../hook-message-injector"
-import { join } from "node:path"
-import { pruneStaleTasksAndNotifications, type SessionStatusMap } from "./task-poller"
-import { checkAndInterruptStaleTasks } from "./task-poller"
+import { ConcurrencyManager } from "./concurrency"
+import {
+  POLLING_INTERVAL_MS,
+  type QueueItem,
+  TASK_CLEANUP_DELAY_MS,
+  TASK_TTL_MS,
+} from "./constants"
+import { formatDuration } from "./duration-formatter"
+import {
+  extractErrorMessage,
+  extractErrorName,
+  extractErrorStatusCode,
+  getSessionErrorMessage,
+  isAbortedSessionError,
+  isRecord,
+} from "./error-classifier"
+import { tryFallbackRetry } from "./fallback-retry-handler"
+import {
+  type CircuitBreakerSettings,
+  detectRepetitiveToolUse,
+  recordToolCall,
+  resolveCircuitBreakerSettings,
+} from "./loop-detector"
+import { ParentWakeNotifier, type ParentWakePromptContext } from "./parent-wake-notifier"
+import { registerManagerForCleanup, unregisterManagerForCleanup } from "./process-cleanup"
 import { removeTaskToastTracking } from "./remove-task-toast-tracking"
-import { abortWithTimeout } from "./abort-with-timeout"
 import {
   MIN_SESSION_GONE_POLLS,
   verifySessionExists as verifySessionStillExists,
 } from "./session-existence"
+import { handleSessionIdleBackgroundEvent } from "./session-idle-event-handler"
 import { isActiveSessionStatus, isTerminalSessionStatus } from "./session-status-classifier"
-import {
-  detectRepetitiveToolUse,
-  recordToolCall,
-  resolveCircuitBreakerSettings,
-  type CircuitBreakerSettings,
-} from "./loop-detector"
+import { buildFallbackBody, FALLBACK_AGENT, isAgentNotFoundError } from "./spawner"
 import {
   createSubagentDepthLimitError,
   getMaxSubagentDepth,
   resolveSubagentSpawnContext,
   type SubagentSpawnContext,
 } from "./subagent-spawn-limits"
-import { ParentWakeNotifier, type ParentWakePromptContext } from "./parent-wake-notifier"
+import { TaskHistory } from "./task-history"
+import { checkAndInterruptStaleTasks, pruneStaleTasksAndNotifications, type SessionStatusMap } from "./task-poller"
+import {
+  archiveBackgroundTask,
+  forgetBackgroundTask,
+  getRegisteredBackgroundTask,
+  rememberBackgroundTask,
+} from "./task-registry"
+import type {
+  BackgroundTask,
+  BackgroundTaskAttempt,
+  LaunchInput,
+  ResumeInput,
+} from "./types"
+
 type OpencodeClient = PluginInput["client"]
 
 type ResumeTaskSnapshot = {
@@ -111,6 +119,13 @@ type ResumeTaskSnapshot = {
   concurrencyGroup?: string
 }
 
+const TERMINAL_BACKGROUND_TASK_STATUSES = new Set<BackgroundTask["status"]>([
+  "completed",
+  "error",
+  "cancelled",
+  "interrupt",
+])
+
 const PENDING_PARENT_WAKE_RETRY_MS = 1_000
 const PENDING_PARENT_WAKE_DEBOUNCE_MS = 100
 const PARENT_WAKE_ACCEPTED_MESSAGE_SKEW_MS = 5_000
@@ -376,6 +391,7 @@ export class BackgroundManager {
   private addTask(task: BackgroundTask): void {
     this.completedTaskArchive.delete(task.id)
     this.tasks.set(task.id, task)
+    rememberBackgroundTask(task)
     if (!task.parentSessionId) {
       return
     }
@@ -387,6 +403,7 @@ export class BackgroundManager {
 
   private removeTask(task: BackgroundTask): void {
     this.archiveCompletedTask(task)
+    archiveBackgroundTask(task)
     this.tasks.delete(task.id)
     this.removeTaskFromParentIndex(task.id, task.parentSessionId)
   }
@@ -557,6 +574,8 @@ export class BackgroundManager {
         parentTools: input.parentTools,
         model: input.model,
         fallbackChain: input.fallbackChain,
+        skillContent: input.skillContent,
+        sessionPermission: input.sessionPermission,
         attemptCount: 0,
         category: input.category,
         onSessionCreated: input.onSessionCreated,
@@ -659,6 +678,7 @@ export class BackgroundManager {
 
           // Abort the orphaned session if one was created before the error
           if (item.task.sessionId) {
+            clearDelegatedChildSessionBootstrap(item.task.sessionId)
             await this.abortSessionWithLogging(item.task.sessionId, "startTask error cleanup")
           }
 
@@ -729,6 +749,7 @@ export class BackgroundManager {
     const sessionID = createResult.data.id
 
     if (task.status === "cancelled") {
+      clearDelegatedChildSessionBootstrap(sessionID)
       await this.abortSessionWithLogging(sessionID, "cancelled pre-start cleanup")
       this.concurrencyManager.release(concurrencyKey)
       return
@@ -737,8 +758,11 @@ export class BackgroundManager {
     await input.onSessionCreated?.(sessionID)
     this.settlePreStartDescendantReservation(task)
     subagentSessions.add(sessionID)
+    setSessionAgent(sessionID, input.agent)
 
     if (this.tasks.get(task.id)?.status === "cancelled") {
+      clearDelegatedChildSessionBootstrap(sessionID)
+      clearSessionAgent(sessionID)
       await this.abortSessionWithLogging(sessionID, "cancelled during launch setup")
       subagentSessions.delete(sessionID)
       if (task.rootSessionId) {
@@ -750,6 +774,8 @@ export class BackgroundManager {
 
     const boundAttempt = bindAttemptSession(task, attemptID, sessionID, input.model)
     if (!boundAttempt) {
+      clearDelegatedChildSessionBootstrap(sessionID)
+      clearSessionAgent(sessionID)
       await this.abortSessionWithLogging(sessionID, "stale attempt binding cleanup")
       subagentSessions.delete(sessionID)
       if (task.rootSessionId) {
@@ -805,21 +831,6 @@ The fallback retry session is now created and can be inspected directly.
     this.taskHistory.record(input.parentSessionId, { id: task.id, sessionID, agent: input.agent, description: input.description, status: "running", category: input.category, startedAt: task.startedAt })
     this.startPolling()
 
-    log("[background-agent] Launching task:", { taskId: task.id, sessionID, agent: input.agent })
-
-    const toastManager = getTaskToastManager()
-    if (toastManager) {
-      toastManager.updateTask(task.id, "running")
-    }
-
-    log("[background-agent] Calling prompt (fire-and-forget) for launch with:", {
-      sessionID,
-      agent: input.agent,
-      model: input.model,
-      hasSkillContent: !!input.skillContent,
-      promptLength: input.prompt.length,
-    })
-
     // Fire-and-forget prompt via promptAsync (no response body needed)
     // OpenCode prompt payload accepts model provider/model IDs and top-level variant only.
     // Temperature/topP and provider-specific options are applied through chat.params.
@@ -835,23 +846,46 @@ The fallback retry session is now created and can be inspected directly.
       applySessionPromptParams(sessionID, input.model)
     }
 
+    const launchTools = {
+      task: false,
+      call_omo_agent: true,
+      question: false,
+      ...getAgentToolRestrictions(input.agent, {
+        includeTeamToolDenylist: input.teamRunId === undefined,
+      }),
+    }
+    setSessionTools(sessionID, launchTools)
+
+    log("[background-agent] Launching task:", { taskId: task.id, sessionID, agent: input.agent })
+    registerDelegatedChildSessionBootstrap({
+      sessionID,
+      promptText: input.prompt,
+      fallbackChain: input.fallbackChain,
+      category: input.category,
+      system: input.skillContent,
+      tools: launchTools,
+      modelFallbackControllerAccessor: this.modelFallbackControllerAccessor,
+    })
+
+    const toastManager = getTaskToastManager()
+    if (toastManager) {
+      toastManager.updateTask(task.id, "running")
+    }
+
+    log("[background-agent] Calling prompt (fire-and-forget) for launch with:", {
+      sessionID,
+      agent: input.agent,
+      model: input.model,
+      hasSkillContent: !!input.skillContent,
+      promptLength: input.prompt.length,
+    })
+
     const promptBody = {
       agent: input.agent,
       ...(launchModel ? { model: launchModel } : {}),
       ...(launchVariant ? { variant: launchVariant } : {}),
       system: input.skillContent,
-      tools: (() => {
-        const tools = {
-          task: false,
-          call_omo_agent: true,
-          question: false,
-          ...getAgentToolRestrictions(input.agent, {
-            includeTeamToolDenylist: input.teamRunId === undefined,
-          }),
-        }
-        setSessionTools(sessionID, tools)
-        return tools
-      })(),
+      tools: launchTools,
       parts: [createInternalAgentTextPart(input.prompt)],
     }
 
@@ -870,7 +904,18 @@ The fallback retry session is now created and can be inspected directly.
           const fallbackBody = buildFallbackBody(promptBody, FALLBACK_AGENT, {
             includeTeamToolDenylist: input.teamRunId === undefined,
           })
-          setSessionTools(sessionID, fallbackBody.tools as Record<string, boolean>)
+          const fallbackTools = fallbackBody.tools as Record<string, boolean>
+          setSessionTools(sessionID, fallbackTools)
+          updateSessionAgent(sessionID, FALLBACK_AGENT)
+          registerDelegatedChildSessionBootstrap({
+            sessionID,
+            promptText: input.prompt,
+            fallbackChain: input.fallbackChain,
+            category: input.category,
+            system: input.skillContent,
+            tools: fallbackTools,
+            modelFallbackControllerAccessor: this.modelFallbackControllerAccessor,
+          })
           await promptWithRetryInDirectory(this.client, {
             path: { id: sessionID },
             body: fallbackBody,
@@ -926,6 +971,7 @@ The fallback retry session is now created and can be inspected directly.
 
         // Abort the session to prevent infinite polling hang
         // Awaited to prevent dangling promise during subagent teardown (Bun/WebKit SIGABRT)
+        clearDelegatedChildSessionBootstrap(sessionID)
         await this.abortSessionWithLogging(sessionID, "launch error cleanup")
 
         this.markForNotification(existingTask)
@@ -960,7 +1006,7 @@ The fallback retry session is now created and can be inspected directly.
   }
 
   getTask(id: string): BackgroundTask | undefined {
-    return this.tasks.get(id) ?? this.completedTaskArchive.get(id)
+    return this.tasks.get(id) ?? this.completedTaskArchive.get(id) ?? getRegisteredBackgroundTask(id)
   }
 
   getTasksByParentSession(sessionID: string): BackgroundTask[] {
@@ -1313,6 +1359,7 @@ The fallback retry session is now created and can be inspected directly.
       // Abort the session to prevent infinite polling hang
       // Awaited to prevent dangling promise during subagent teardown (Bun/WebKit SIGABRT)
       if (existingTask.sessionId) {
+        clearDelegatedChildSessionBootstrap(existingTask.sessionId)
         await this.abortSessionWithLogging(existingTask.sessionId, "resume error cleanup")
       }
 
@@ -1650,6 +1697,7 @@ The fallback retry session is now created and can be inspected directly.
       }
 
       this.rootDescendantCounts.delete(sessionID)
+      clearDelegatedChildSessionBootstrap(sessionID)
       SessionCategoryRegistry.remove(sessionID)
     }
 
@@ -1732,6 +1780,7 @@ The fallback retry session is now created and can be inspected directly.
     this.scheduleTaskRemoval(task.id)
 
     if (task.sessionId) {
+      clearDelegatedChildSessionBootstrap(task.sessionId)
       SessionCategoryRegistry.remove(task.sessionId)
       await this.abortSessionWithLogging(task.sessionId, `${reason} cleanup`)
     }
@@ -1838,6 +1887,7 @@ The fallback retry session is now created and can be inspected directly.
     }
     this.scheduleTaskRemoval(task.id)
     if (task.sessionId) {
+      clearDelegatedChildSessionBootstrap(task.sessionId)
       SessionCategoryRegistry.remove(task.sessionId)
     }
 
@@ -1895,6 +1945,7 @@ The task was re-queued on a fallback model after a retryable failure.
     if (retried && previousSessionID) {
       this.clearSessionOutputObserved(previousSessionID)
       this.clearSessionTodoObservation(previousSessionID)
+      clearDelegatedChildSessionBootstrap(previousSessionID)
       subagentSessions.delete(previousSessionID)
     }
     return retried
@@ -2059,6 +2110,7 @@ The task was re-queued on a fallback model after a retryable failure.
       this.clearTaskHistoryWhenParentTasksGone(task.parentSessionId)
       if (task.sessionId) {
         subagentSessions.delete(task.sessionId)
+        clearDelegatedChildSessionBootstrap(task.sessionId)
         SessionCategoryRegistry.remove(task.sessionId)
       }
       log("[background-agent] Removed completed task from memory:", taskId)
@@ -2134,6 +2186,7 @@ The task was re-queued on a fallback model after a retryable failure.
       // Awaited to prevent dangling promise during subagent teardown (Bun/WebKit SIGABRT)
       await this.abortSessionWithLogging(task.sessionId, `task cancellation (${source})`)
 
+      clearDelegatedChildSessionBootstrap(task.sessionId)
       SessionCategoryRegistry.remove(task.sessionId)
     }
 
@@ -2259,6 +2312,7 @@ The task was re-queued on a fallback model after a retryable failure.
       // Awaited to prevent dangling promise during subagent teardown (Bun/WebKit SIGABRT)
       await this.abortSessionWithLogging(task.sessionId, `task completion (${source})`)
 
+      clearDelegatedChildSessionBootstrap(task.sessionId)
       SessionCategoryRegistry.remove(task.sessionId)
     }
 
@@ -2588,6 +2642,7 @@ The task was re-queued on a fallback model after a retryable failure.
     removeTaskToastTracking(task.id)
     this.scheduleTaskRemoval(task.id)
     if (task.sessionId) {
+      clearDelegatedChildSessionBootstrap(task.sessionId)
       SessionCategoryRegistry.remove(task.sessionId)
     }
 
@@ -2775,6 +2830,12 @@ The task was re-queued on a fallback model after a retryable failure.
 
     // Release concurrency for all running tasks
     for (const task of this.tasks.values()) {
+      if (TERMINAL_BACKGROUND_TASK_STATUSES.has(task.status)) {
+        archiveBackgroundTask(task)
+      } else {
+        forgetBackgroundTask(task.id)
+      }
+
       if (task.concurrencyKey) {
         this.concurrencyManager.release(task.concurrencyKey)
         task.concurrencyKey = undefined
@@ -2795,6 +2856,7 @@ The task was re-queued on a fallback model after a retryable failure.
 
     for (const sessionID of trackedSessionIDs) {
       subagentSessions.delete(sessionID)
+      clearDelegatedChildSessionBootstrap(sessionID)
       SessionCategoryRegistry.remove(sessionID)
     }
 

src/features/background-agent/spawner.test.ts

@@ -1,10 +1,10 @@
-import { describe, test, expect, mock, afterEach } from "bun:test"
-import { createTask, startTask } from "./spawner"
-import type { BackgroundTask } from "./types"
+import { afterEach, describe, expect, mock, test } from "bun:test"
 import {
   clearSessionPromptParams,
   getSessionPromptParams,
 } from "../../shared/session-prompt-params-state"
+import { createTask, startTask } from "./spawner"
+import type { BackgroundTask } from "./types"
 
 describe("background-agent spawner agent-not-found fallback", () => {
   afterEach(() => {
@@ -694,6 +694,67 @@ describe("background-agent spawner fallback model promotion", () => {
     expect(promptCalls).toHaveLength(1)
     expect(promptCalls[0]?.body?.agent).toBe("Hephaestus - Deep Agent")
   })
+
+  test("persists the same normalized agent used by promptAsync into session-agent state (GH-3259 follow-up)", async () => {
+    //#given - ZWSP+sort-prefix wrapped agent name
+    const promptCalls: Array<{ body?: { agent?: string } }> = []
+    const sessionID = "ses_child_normalized"
+    const wrappedAgent = "\u200B\u200B5|Hephaestus - Deep Agent"
+
+    const client = {
+      session: {
+        get: async () => ({ data: { directory: "/parent/dir" } }),
+        create: async () => ({ data: { id: sessionID } }),
+        promptAsync: async (args?: { body?: { agent?: string } }) => {
+          promptCalls.push(args ?? {})
+          return {}
+        },
+      },
+    }
+
+    const { _resetForTesting: resetState, getSessionAgent } = await import("../claude-code-session-state")
+    resetState()
+
+    const task = createTask({
+      description: "Normalized agent storage",
+      prompt: "Do work",
+      agent: wrappedAgent,
+      parentSessionId: "ses_parent",
+      parentMessageId: "msg_parent",
+    })
+
+    const item = {
+      task,
+      input: {
+        description: task.description,
+        prompt: task.prompt,
+        agent: task.agent,
+        parentSessionId: task.parentSessionId,
+        parentMessageId: task.parentMessageId,
+        parentModel: task.parentModel,
+        parentAgent: task.parentAgent,
+        model: task.model,
+      },
+    }
+
+    const ctx = {
+      client,
+      directory: "/fallback",
+      concurrencyManager: { release: () => {} },
+      tmuxEnabled: false,
+      onTaskError: () => {},
+    }
+
+    //#when
+    await startTask(item as never, ctx as never)
+    await new Promise((resolve) => setTimeout(resolve, 0))
+
+    //#then
+    expect(promptCalls).toHaveLength(1)
+    const dispatchedAgent = promptCalls[0]?.body?.agent
+    expect(dispatchedAgent).toBe("Hephaestus - Deep Agent")
+    expect(getSessionAgent(sessionID)).toBe(dispatchedAgent)
+  })
 })
 
 describe("background-agent spawner tmux callback ordering", () => {

src/features/background-agent/spawner.ts

@@ -1,13 +1,14 @@
-import type { BackgroundTask, LaunchInput, ResumeInput } from "./types"
-import type { OpencodeClient, OnSubagentSessionCreated, QueueItem } from "./constants"
-import { log, getAgentToolRestrictions, createInternalAgentTextPart, promptWithRetryInDirectory } from "../../shared"
+import { createInternalAgentTextPart, getAgentToolRestrictions, log, promptWithRetryInDirectory } from "../../shared"
+import { stripAgentListSortPrefix } from "../../shared/agent-display-names"
 import { releasePromptAsyncReservation } from "../../shared/prompt-async-gate"
 import { applySessionPromptParams } from "../../shared/session-prompt-params-helpers"
-import { subagentSessions } from "../claude-code-session-state"
-import { getTaskToastManager } from "../task-toast-manager"
+import { setSessionTools } from "../../shared/session-tools-store"
 import { isInsideTmux } from "../../shared/tmux"
-import { stripAgentListSortPrefix } from "../../shared/agent-display-names"
+import { setSessionAgent, subagentSessions, updateSessionAgent } from "../claude-code-session-state"
+import { getTaskToastManager } from "../task-toast-manager"
 import type { ConcurrencyManager } from "./concurrency"
+import type { OnSubagentSessionCreated, OpencodeClient, QueueItem } from "./constants"
+import type { BackgroundTask, LaunchInput, ResumeInput } from "./types"
 
 export const FALLBACK_AGENT = "general"
 
@@ -65,7 +66,13 @@ export function createTask(input: LaunchInput): BackgroundTask {
     teamRunId: input.teamRunId,
     parentModel: input.parentModel,
     parentAgent: input.parentAgent,
+    parentTools: input.parentTools,
     model: input.model,
+    fallbackChain: input.fallbackChain,
+    skillContent: input.skillContent,
+    sessionPermission: input.sessionPermission,
+    category: input.category,
+    isUnstableAgent: input.isUnstableAgent,
     onSessionCreated: input.onSessionCreated,
   }
 }
@@ -116,8 +123,10 @@ export async function startTask(
   }
 
   const sessionID = createResult.data.id
+  const normalizedAgent = stripAgentListSortPrefix(input.agent)
   await input.onSessionCreated?.(sessionID)
   subagentSessions.add(sessionID)
+  setSessionAgent(sessionID, normalizedAgent)
 
   task.status = "running"
   task.startedAt = new Date()
@@ -129,7 +138,7 @@ export async function startTask(
   task.concurrencyKey = concurrencyKey
   task.concurrencyGroup = concurrencyKey
 
-  log("[background-agent] Launching task:", { taskId: task.id, sessionID, agent: input.agent })
+  log("[background-agent] Launching task:", { taskId: task.id, sessionID, agent: normalizedAgent })
 
   const toastManager = getTaskToastManager()
   if (toastManager) {
@@ -138,7 +147,7 @@ export async function startTask(
 
   log("[background-agent] Calling prompt (fire-and-forget) for launch with:", {
     sessionID,
-    agent: input.agent,
+    agent: normalizedAgent,
     model: input.model,
     hasSkillContent: !!input.skillContent,
     promptLength: input.prompt.length,
@@ -151,7 +160,6 @@ export async function startTask(
       }
     : undefined
   const launchVariant = input.model?.variant
-  const normalizedAgent = stripAgentListSortPrefix(input.agent)
 
   applySessionPromptParams(sessionID, input.model)
 
@@ -170,6 +178,7 @@ export async function startTask(
     },
     parts: [createInternalAgentTextPart(input.prompt)],
   }
+  setSessionTools(sessionID, promptBody.tools)
 
   // Must fire BEFORE tmux callback: attach client needs session activity to render TUI.
   const promptChain = promptWithRetryInDirectory(client, {
@@ -184,11 +193,15 @@ export async function startTask(
       })
       try {
         releasePromptAsyncReservation(sessionID, "model-suggestion-retry")
+        const fallbackBody = buildFallbackBody(promptBody, FALLBACK_AGENT, {
+          includeTeamToolDenylist: input.teamRunId === undefined,
+        })
+        const fallbackTools = fallbackBody.tools as Record<string, boolean>
+        setSessionTools(sessionID, fallbackTools)
+        updateSessionAgent(sessionID, FALLBACK_AGENT)
         await promptWithRetryInDirectory(client, {
           path: { id: sessionID },
-          body: buildFallbackBody(promptBody, FALLBACK_AGENT, {
-            includeTeamToolDenylist: input.teamRunId === undefined,
-          }),
+          body: fallbackBody,
         }, parentDirectory)
         task.agent = FALLBACK_AGENT
         return
@@ -310,6 +323,7 @@ export async function resumeTask(
     },
     parts: [createInternalAgentTextPart(input.prompt)],
   }
+  setSessionTools(sessionID, resumeBody.tools)
 
   promptWithRetryInDirectory(client, {
     path: { id: sessionID },
@@ -323,11 +337,15 @@ export async function resumeTask(
       })
       try {
         releasePromptAsyncReservation(sessionID, "model-suggestion-retry")
+        const fallbackBody = buildFallbackBody(resumeBody, FALLBACK_AGENT, {
+          includeTeamToolDenylist: task.teamRunId === undefined,
+        })
+        const fallbackTools = fallbackBody.tools as Record<string, boolean>
+        setSessionTools(sessionID, fallbackTools)
+        updateSessionAgent(sessionID, FALLBACK_AGENT)
         await promptWithRetryInDirectory(client, {
           path: { id: sessionID },
-          body: buildFallbackBody(resumeBody, FALLBACK_AGENT, {
-            includeTeamToolDenylist: task.teamRunId === undefined,
-          }),
+          body: fallbackBody,
         }, directory)
         task.agent = FALLBACK_AGENT
         return

src/features/background-agent/task-registry.ts

@@ -0,0 +1,137 @@
+import type { BackgroundTask } from "./types"
+
+const MAX_COMPLETED_TASK_REGISTRY_SIZE = 100
+const REGISTRY_KEY = "__omoBackgroundTaskRegistry"
+
+type BackgroundTaskRegistry = {
+  activeTasks: Map<string, () => BackgroundTask>
+  completedTasks: Map<string, BackgroundTask>
+}
+
+type GlobalWithBackgroundTaskRegistry = typeof globalThis & {
+  [REGISTRY_KEY]?: BackgroundTaskRegistry
+}
+
+const TERMINAL_TASK_STATUSES = new Set<BackgroundTask["status"]>([
+  "completed",
+  "error",
+  "cancelled",
+  "interrupt",
+])
+
+function getRegistry(): BackgroundTaskRegistry {
+  const registryGlobal = globalThis as GlobalWithBackgroundTaskRegistry
+  registryGlobal[REGISTRY_KEY] ??= {
+    activeTasks: new Map<string, () => BackgroundTask>(),
+    completedTasks: new Map<string, BackgroundTask>(),
+  }
+  const registry = registryGlobal[REGISTRY_KEY]
+  return registry
+}
+
+function cloneProgress(progress: BackgroundTask["progress"]): BackgroundTask["progress"] {
+  if (!progress) {
+    return undefined
+  }
+
+  return {
+    ...progress,
+    countedToolPartIDs: progress.countedToolPartIDs ? new Set(progress.countedToolPartIDs) : undefined,
+  }
+}
+
+function cloneAttempts(attempts: BackgroundTask["attempts"]): BackgroundTask["attempts"] {
+  if (!attempts) {
+    return undefined
+  }
+
+  return attempts.map((attempt) => ({ ...attempt }))
+}
+
+function cloneRegisteredTask(task: BackgroundTask): BackgroundTask {
+  return {
+    id: task.id,
+    rootSessionId: task.rootSessionId,
+    parentSessionId: task.parentSessionId,
+    parentMessageId: task.parentMessageId,
+    teamRunId: task.teamRunId,
+    description: task.description,
+    prompt: "[redacted]",
+    agent: task.agent,
+    spawnDepth: task.spawnDepth,
+    sessionId: task.sessionId,
+    status: task.status,
+    queuedAt: task.queuedAt,
+    startedAt: task.startedAt,
+    completedAt: task.completedAt,
+    result: task.result,
+    progress: cloneProgress(task.progress),
+    parentModel: task.parentModel,
+    model: task.model,
+    fallbackChain: task.fallbackChain,
+    attemptCount: task.attemptCount,
+    concurrencyKey: task.concurrencyKey,
+    concurrencyGroup: task.concurrencyGroup,
+    parentAgent: task.parentAgent,
+    parentTools: task.parentTools,
+    isUnstableAgent: task.isUnstableAgent,
+    error: task.error,
+    category: task.category,
+    retryNotification: task.retryNotification ? { ...task.retryNotification } : undefined,
+    attempts: cloneAttempts(task.attempts),
+    currentAttemptID: task.currentAttemptID,
+    lastMsgCount: task.lastMsgCount,
+    stablePolls: task.stablePolls,
+    consecutiveMissedPolls: task.consecutiveMissedPolls,
+  }
+}
+
+function trimCompletedTasks(registry: BackgroundTaskRegistry): void {
+  while (registry.completedTasks.size > MAX_COMPLETED_TASK_REGISTRY_SIZE) {
+    const oldestTaskID = registry.completedTasks.keys().next().value
+    if (typeof oldestTaskID !== "string") {
+      return
+    }
+    registry.completedTasks.delete(oldestTaskID)
+  }
+}
+
+export function rememberBackgroundTask(task: BackgroundTask): void {
+  const registry = getRegistry()
+  registry.completedTasks.delete(task.id)
+  registry.activeTasks.set(task.id, () => cloneRegisteredTask(task))
+}
+
+export function archiveBackgroundTask(task: BackgroundTask): void {
+  const registry = getRegistry()
+  registry.activeTasks.delete(task.id)
+  registry.completedTasks.delete(task.id)
+  if (!task.sessionId || !TERMINAL_TASK_STATUSES.has(task.status)) {
+    return
+  }
+  registry.completedTasks.set(task.id, cloneRegisteredTask(task))
+  trimCompletedTasks(registry)
+}
+
+export function getRegisteredBackgroundTask(taskID: string): BackgroundTask | undefined {
+  const registry = getRegistry()
+  const activeTask = registry.activeTasks.get(taskID)
+  if (activeTask) {
+    return activeTask()
+  }
+
+  const completedTask = registry.completedTasks.get(taskID)
+  return completedTask ? cloneRegisteredTask(completedTask) : undefined
+}
+
+export function forgetBackgroundTask(taskID: string): void {
+  const registry = getRegistry()
+  registry.activeTasks.delete(taskID)
+  registry.completedTasks.delete(taskID)
+}
+
+export function clearBackgroundTaskRegistryForTesting(): void {
+  const registry = getRegistry()
+  registry.activeTasks.clear()
+  registry.completedTasks.clear()
+}

src/features/background-agent/types.ts

@@ -73,6 +73,8 @@ export interface BackgroundTask {
   parentAgent?: string
   /** Parent session's tool restrictions for notification prompts */
   parentTools?: Record<string, boolean>
+  skillContent?: string
+  sessionPermission?: SessionPermissionRule[]
   /** Marks if the task was launched from an unstable agent/category */
   isUnstableAgent?: boolean
   /** Category used for this task (e.g., 'quick', 'visual-engineering') */

src/hooks/runtime-fallback/auto-retry.ts

@@ -6,8 +6,9 @@ import { getSessionAgent } from "../../features/claude-code-session-state"
 import { getFallbackModelsForSession } from "./fallback-models"
 import { prepareFallback } from "./fallback-state"
 import { SessionCategoryRegistry } from "../../shared/session-category-registry"
+import { clearDelegatedChildSessionBootstrap } from "../../shared/delegated-child-session-bootstrap"
 import { buildRetryModelPayload } from "./retry-model-payload"
-import { getLastUserRetryParts } from "./last-user-retry-parts"
+import { getLastUserRetryPayload } from "./last-user-retry-parts"
 import { extractSessionMessages } from "./session-messages"
 import { resolveRegisteredAgentName } from "../../features/claude-code-session-state"
 import {
@@ -143,7 +144,8 @@ export function createAutoRetryHelpers(deps: HookDeps) {
         path: { id: sessionID },
         query: { directory: ctx.directory },
       })
-      const retryParts = getLastUserRetryParts(messagesResp)
+      const retryPayload = getLastUserRetryPayload(messagesResp, sessionID)
+      const retryParts = retryPayload.retryParts
       if (retryParts.length > 0) {
         log(`[${HOOK_NAME}] Auto-retrying with fallback model (${source})`, {
           sessionID,
@@ -165,6 +167,8 @@ export function createAutoRetryHelpers(deps: HookDeps) {
             body: {
               ...(launchAgent ? { agent: launchAgent } : {}),
               ...retryModelPayload,
+              ...(retryPayload.system ? { system: retryPayload.system } : {}),
+              ...(retryPayload.tools ? { tools: retryPayload.tools } : {}),
               parts: retryParts,
             },
             query: { directory: ctx.directory },
@@ -239,6 +243,7 @@ export function createAutoRetryHelpers(deps: HookDeps) {
         sessionRetryInFlight.delete(sessionID)
         sessionAwaitingFallbackResult.delete(sessionID)
         clearSessionFallbackTimeout(sessionID)
+        clearDelegatedChildSessionBootstrap(sessionID)
         SessionCategoryRegistry.remove(sessionID)
         sessionStatusRetryKeys.delete(sessionID)
         cleanedCount++

src/hooks/runtime-fallback/index.test.ts

@@ -1,8 +1,14 @@
-import { describe, expect, test, beforeEach, afterEach, mock } from "bun:test"
-import type { RuntimeFallbackConfig, OhMyOpenCodeConfig } from "../../config"
+import { afterEach, beforeEach, describe, expect, mock, test } from "bun:test"
+import { unsafeTestValue } from "../../../test-support/unsafe-test-value"
+import type { OhMyOpenCodeConfig, RuntimeFallbackConfig } from "../../config"
+import {
+  clearAllDelegatedChildSessionBootstrap,
+  getDelegatedChildSessionBootstrap,
+  registerDelegatedChildSessionBootstrap,
+} from "../../shared/delegated-child-session-bootstrap"
 import * as loggerModule from "../../shared/logger"
 import { SessionCategoryRegistry } from "../../shared/session-category-registry"
-import { unsafeTestValue } from "../../../test-support/unsafe-test-value"
+import type { RuntimeFallbackPluginInput } from "./types"
 
 type RuntimeFallbackModule = typeof import("./hook")
 
@@ -16,6 +22,7 @@ describe("runtime-fallback", () => {
     logCalls = []
     toastCalls = []
     SessionCategoryRegistry.clear()
+    clearAllDelegatedChildSessionBootstrap()
 
     const cacheBuster = `${Date.now()}-${Math.random()}`
 
@@ -32,6 +39,7 @@ describe("runtime-fallback", () => {
 
   afterEach(() => {
     SessionCategoryRegistry.clear()
+    clearAllDelegatedChildSessionBootstrap()
     mock.restore()
   })
 
@@ -42,8 +50,8 @@ describe("runtime-fallback", () => {
       abort?: (args: unknown) => Promise<unknown>
       status?: () => Promise<unknown>
     }
-  }) {
-    return unsafeTestValue({
+  }): RuntimeFallbackPluginInput {
+    return unsafeTestValue<RuntimeFallbackPluginInput>({
       client: {
         tui: {
           showToast: async (opts: { body: { title: string; message: string; variant: string; duration: number } }) => {
@@ -489,6 +497,122 @@ describe("runtime-fallback", () => {
       })
     })
 
+    test("should retry delegated child session from bootstrap when history has no user prompt", async () => {
+      const promptCalls: Array<Record<string, unknown>> = []
+      const hook = createRuntimeFallbackHook(
+        createMockPluginInput({
+          session: {
+            messages: async () => ({ data: [] }),
+            promptAsync: async (args) => {
+              promptCalls.push(args as Record<string, unknown>)
+              return {}
+            },
+          },
+        }),
+        {
+          config: createMockConfig({ notify_on_fallback: false }),
+          pluginConfig: createMockPluginConfigWithCategoryModel(
+            "quick",
+            "anthropic/claude-haiku-4-5",
+            ["openai/gpt-5.4(high)"],
+          ),
+        },
+      )
+      const sessionID = "test-delegated-empty-history-bootstrap"
+      registerDelegatedChildSessionBootstrap({
+        sessionID,
+        promptText: "inspect src/tools/delegate-task and report the issue",
+        category: "quick",
+        system: "delegated child system prompt",
+        tools: { call_omo_agent: true, question: false, task: false },
+      })
+
+      await hook.event({
+        event: {
+          type: "session.error",
+          properties: {
+            sessionID,
+            error: { statusCode: 429, message: "Rate limit exceeded before history persisted" },
+          },
+        },
+      })
+
+      expect(promptCalls).toHaveLength(1)
+      const promptBody = promptCalls[0]?.body as {
+        model?: { providerID?: string; modelID?: string }
+        parts?: Array<{ type?: string; text?: string }>
+        system?: string
+        tools?: Record<string, boolean>
+        variant?: string
+      } | undefined
+      expect(promptBody?.model).toEqual({ providerID: "openai", modelID: "gpt-5.4" })
+      expect(promptBody?.variant).toBe("high")
+      expect(promptBody?.system).toBe("delegated child system prompt")
+      expect(promptBody?.tools?.question).toBe(false)
+      expect(promptBody?.tools?.call_omo_agent).toBe(true)
+      expect(promptBody?.parts?.[0]?.text).toContain("inspect src/tools/delegate-task")
+    })
+
+    test("should use persisted user prompt while preserving delegated bootstrap launch context", async () => {
+      const promptCalls: Array<Record<string, unknown>> = []
+      const sessionID = "test-delegated-history-prefers-persisted-user"
+      const hook = createRuntimeFallbackHook(
+        createMockPluginInput({
+          session: {
+            messages: async () => ({
+              data: [
+                {
+                  info: { role: "user" },
+                  parts: [{ type: "text", text: "persisted child task prompt" }],
+                },
+              ],
+            }),
+            promptAsync: async (args) => {
+              promptCalls.push(args as Record<string, unknown>)
+              return {}
+            },
+          },
+        }),
+        {
+          config: createMockConfig({ notify_on_fallback: false }),
+          pluginConfig: createMockPluginConfigWithCategoryModel(
+            "test",
+            "anthropic/claude-haiku-4-5",
+            ["openai/gpt-5.4"],
+          ),
+        },
+      )
+      registerDelegatedChildSessionBootstrap({
+        sessionID,
+        promptText: "bootstrap copy should not be reused",
+        system: "persisted delegated child system prompt",
+        tools: { call_omo_agent: true, question: false, task: false },
+      })
+      SessionCategoryRegistry.register(sessionID, "test")
+
+      await hook.event({
+        event: {
+          type: "session.error",
+          properties: {
+            sessionID,
+            error: { statusCode: 429, message: "Rate limit after prompt persisted" },
+          },
+        },
+      })
+
+      expect(promptCalls).toHaveLength(1)
+      const promptBody = promptCalls[0]?.body as {
+        parts?: Array<{ type?: string; text?: string }>
+        system?: string
+        tools?: Record<string, boolean>
+      } | undefined
+      expect(promptBody?.parts?.[0]?.text).toBe("persisted child task prompt")
+      expect(promptBody?.system).toBe("persisted delegated child system prompt")
+      expect(promptBody?.tools?.question).toBe(false)
+      expect(promptBody?.tools?.call_omo_agent).toBe(true)
+      expect(getDelegatedChildSessionBootstrap(sessionID)).toBeUndefined()
+    })
+
     test("should trigger fallback on Copilot auto-retry signal in message.updated", async () => {
       const hook = createRuntimeFallbackHook(createMockPluginInput(), {
         config: createMockConfig({ notify_on_fallback: false }),

src/hooks/runtime-fallback/last-user-retry-parts.ts

@@ -1,15 +1,36 @@
 import { extractSessionMessages } from "./session-messages"
+import {
+  clearDelegatedChildSessionBootstrap,
+  getDelegatedChildSessionBootstrap,
+} from "../../shared/delegated-child-session-bootstrap"
+
+type RetryPart = { type: "text"; text: string }
+
+export type LastUserRetryPayload = {
+  retryParts: RetryPart[]
+  system?: string
+  tools?: Record<string, boolean>
+}
 
 export function getLastUserRetryParts(
   messagesResponse: unknown,
-): Array<{ type: "text"; text: string }> {
+  sessionID?: string,
+): RetryPart[] {
+  return getLastUserRetryPayload(messagesResponse, sessionID).retryParts
+}
+
+export function getLastUserRetryPayload(
+  messagesResponse: unknown,
+  sessionID?: string,
+): LastUserRetryPayload {
+  const bootstrap = sessionID ? getDelegatedChildSessionBootstrap(sessionID) : undefined
   const messages = extractSessionMessages(messagesResponse)
   const lastUserMessage = messages?.filter((message) => message.info?.role === "user").pop()
   const lastUserParts =
     lastUserMessage?.parts
     ?? (lastUserMessage?.info?.parts as Array<{ type?: string; text?: string }> | undefined)
 
-  return (lastUserParts ?? [])
+  const retryParts = (lastUserParts ?? [])
     .filter(
       (part): part is { type: "text"; text: string } =>
         part.type === "text"
@@ -17,4 +38,25 @@ export function getLastUserRetryParts(
         && part.text.length > 0,
     )
     .map((part) => ({ type: "text" as const, text: part.text }))
+
+  if (retryParts.length > 0) {
+    if (sessionID) {
+      clearDelegatedChildSessionBootstrap(sessionID)
+    }
+    return {
+      retryParts,
+      ...(bootstrap?.system ? { system: bootstrap.system } : {}),
+      ...(bootstrap?.tools ? { tools: bootstrap.tools } : {}),
+    }
+  }
+
+  if (!sessionID) {
+    return { retryParts }
+  }
+
+  return {
+    retryParts: bootstrap?.retryParts ?? [],
+    ...(bootstrap?.system ? { system: bootstrap.system } : {}),
+    ...(bootstrap?.tools ? { tools: bootstrap.tools } : {}),
+  }
 }

src/hooks/runtime-fallback/types.ts

@@ -16,6 +16,8 @@ export interface RuntimeFallbackPluginInput {
         body: {
           agent?: string
           model: { providerID: string; modelID: string }
+          system?: string
+          tools?: Record<string, boolean>
           parts: Array<{ type: "text"; text: string }>
         }
         query: { directory: string }

src/hooks/shared/prompt-async-gate.test.ts

@@ -91,6 +91,36 @@ describe("promptAsyncAfterSessionIdle", () => {
     expect(promptCalls).toBe(1)
   })
 
+  test("#given SDK promptAsync depends on its session receiver #when the gate dispatches #then method binding is preserved", async () => {
+    // given
+    const session = {
+      _client: { accepted: true },
+      async promptAsync(
+        this: { _client: { accepted: boolean } },
+        input: { path: { id: string }, body: { parts: unknown[] } },
+      ) {
+        return { accepted: this._client.accepted, sessionID: input.path.id }
+      },
+    }
+    const client = { session }
+
+    // when
+    const result = await promptAsyncAfterSessionIdle({
+      client,
+      sessionID: "ses_bound_prompt_async",
+      input: { path: { id: "ses_bound_prompt_async" }, body: { parts: [] } },
+      source: "test:bound-prompt-async",
+      settleMs: 0,
+      postDispatchHoldMs: 0,
+    })
+
+    // then
+    expect(result).toEqual({
+      status: "dispatched",
+      response: { accepted: true, sessionID: "ses_bound_prompt_async" },
+    })
+  })
+
   test("#given session.status reports busy #when an internal promptAsync is requested #then no prompt is sent", async () => {
     // given
     let promptCalls = 0
@@ -445,4 +475,34 @@ describe("promptAsyncAfterSessionIdle", () => {
     expect(second.status).toBe("reserved")
     expect(promptCalls).toBe(1)
   })
+
+  test("#given SDK prompt depends on its session receiver #when the gate dispatches #then method binding is preserved", async () => {
+    // given
+    const session = {
+      _client: { accepted: true },
+      async prompt(
+        this: { _client: { accepted: boolean } },
+        input: { path: { id: string }, body: { parts: unknown[] } },
+      ) {
+        return { accepted: this._client.accepted, sessionID: input.path.id }
+      },
+    }
+    const client = { session }
+
+    // when
+    const result = await promptAfterSessionIdle({
+      client,
+      sessionID: "ses_bound_prompt",
+      input: { path: { id: "ses_bound_prompt" }, body: { parts: [] } },
+      source: "test:bound-prompt",
+      settleMs: 0,
+      postDispatchHoldMs: 0,
+    })
+
+    // then
+    expect(result).toEqual({
+      status: "dispatched",
+      response: { accepted: true, sessionID: "ses_bound_prompt" },
+    })
+  })
 })

src/shared/delegated-child-session-bootstrap.ts

@@ -0,0 +1,85 @@
+import type { ModelFallbackControllerAccessor } from "../hooks/model-fallback"
+import { createInternalAgentTextPart } from "./internal-initiator-marker"
+import type { FallbackEntry } from "./model-requirements"
+import { SessionCategoryRegistry } from "./session-category-registry"
+
+export type DelegatedChildSessionRetryPart = {
+  type: "text"
+  text: string
+}
+
+export type DelegatedChildSessionBootstrap = {
+  retryParts: DelegatedChildSessionRetryPart[]
+  fallbackChain?: FallbackEntry[]
+  category?: string
+  system?: string
+  tools?: Record<string, boolean>
+}
+
+const delegatedChildSessionBootstraps = new Map<string, DelegatedChildSessionBootstrap>()
+
+function cloneRetryParts(parts: DelegatedChildSessionRetryPart[]): DelegatedChildSessionRetryPart[] {
+  return parts.map((part) => ({ type: part.type, text: part.text }))
+}
+
+function cloneFallbackChain(fallbackChain: FallbackEntry[] | undefined): FallbackEntry[] | undefined {
+  return fallbackChain?.map((entry) => ({
+    ...entry,
+    providers: [...entry.providers],
+  }))
+}
+
+function cloneTools(tools: Record<string, boolean> | undefined): Record<string, boolean> | undefined {
+  return tools ? { ...tools } : undefined
+}
+
+export function registerDelegatedChildSessionBootstrap(_args: {
+  sessionID: string
+  promptText: string
+  fallbackChain?: FallbackEntry[]
+  category?: string
+  system?: string
+  tools?: Record<string, boolean>
+  modelFallbackControllerAccessor?: ModelFallbackControllerAccessor
+}): void {
+  const retryParts = [createInternalAgentTextPart(_args.promptText)]
+  const fallbackChain = cloneFallbackChain(_args.fallbackChain)
+  const tools = cloneTools(_args.tools)
+  delegatedChildSessionBootstraps.set(_args.sessionID, {
+    retryParts,
+    ...(fallbackChain ? { fallbackChain } : {}),
+    ...(_args.category ? { category: _args.category } : {}),
+    ...(_args.system ? { system: _args.system } : {}),
+    ...(tools ? { tools } : {}),
+  })
+
+  _args.modelFallbackControllerAccessor?.setSessionFallbackChain(_args.sessionID, fallbackChain)
+  if (_args.category) {
+    SessionCategoryRegistry.register(_args.sessionID, _args.category)
+  }
+}
+
+export function getDelegatedChildSessionBootstrap(_sessionID: string): DelegatedChildSessionBootstrap | undefined {
+  const bootstrap = delegatedChildSessionBootstraps.get(_sessionID)
+  if (!bootstrap) {
+    return undefined
+  }
+
+  const fallbackChain = cloneFallbackChain(bootstrap.fallbackChain)
+  const tools = cloneTools(bootstrap.tools)
+  return {
+    retryParts: cloneRetryParts(bootstrap.retryParts),
+    ...(fallbackChain ? { fallbackChain } : {}),
+    ...(bootstrap.category ? { category: bootstrap.category } : {}),
+    ...(bootstrap.system ? { system: bootstrap.system } : {}),
+    ...(tools ? { tools } : {}),
+  }
+}
+
+export function clearDelegatedChildSessionBootstrap(_sessionID: string): void {
+  delegatedChildSessionBootstraps.delete(_sessionID)
+}
+
+export function clearAllDelegatedChildSessionBootstrap(): void {
+  delegatedChildSessionBootstraps.clear()
+}

src/shared/prompt-async-gate.ts

@@ -217,12 +217,13 @@ export async function promptAsyncAfterSessionIdle<TInput = PromptAsyncInput>(arg
   } = args
   const postDispatchHoldMs = args.postDispatchHoldMs ?? DEFAULT_PROMPT_ASYNC_POST_DISPATCH_HOLD_MS
   const dispatchTimeoutMs = args.dispatchTimeoutMs ?? DEFAULT_PROMPT_DISPATCH_TIMEOUT_MS
-  const promptAsync = client.session?.promptAsync
+  const session = client.session
 
-  if (typeof promptAsync !== "function") {
+  if (typeof session?.promptAsync !== "function") {
     log("[prompt-async-gate] promptAsync unavailable", { sessionID, source })
     return { status: "unavailable" }
   }
+  const dispatchPromptAsync = session.promptAsync.bind(session)
 
   return dispatchAfterSessionIdle({
     sessionName: "promptAsync",
@@ -234,7 +235,7 @@ export async function promptAsyncAfterSessionIdle<TInput = PromptAsyncInput>(arg
     postDispatchHoldMs,
     dispatchTimeoutMs,
     checkStatus: args.checkStatus !== false,
-    dispatch: (dispatchInput) => promptAsync(dispatchInput),
+    dispatch: (dispatchInput) => dispatchPromptAsync(dispatchInput),
   })
 }
 
@@ -257,12 +258,13 @@ export async function promptAfterSessionIdle<TInput = PromptAsyncInput>(args: {
   } = args
   const postDispatchHoldMs = args.postDispatchHoldMs ?? DEFAULT_PROMPT_ASYNC_POST_DISPATCH_HOLD_MS
   const dispatchTimeoutMs = args.dispatchTimeoutMs ?? DEFAULT_PROMPT_DISPATCH_TIMEOUT_MS
-  const prompt = client.session?.prompt
+  const session = client.session
 
-  if (typeof prompt !== "function") {
+  if (typeof session?.prompt !== "function") {
     log("[prompt-async-gate] prompt unavailable", { sessionID, source })
     return { status: "unavailable" }
   }
+  const dispatchPrompt = session.prompt.bind(session)
 
   return dispatchAfterSessionIdle({
     sessionName: "prompt",
@@ -274,7 +276,7 @@ export async function promptAfterSessionIdle<TInput = PromptAsyncInput>(args: {
     postDispatchHoldMs,
     dispatchTimeoutMs,
     checkStatus: args.checkStatus !== false,
-    dispatch: (dispatchInput) => prompt(dispatchInput),
+    dispatch: (dispatchInput) => dispatchPrompt(dispatchInput),
   })
 }
 

src/tools/call-omo-agent/sync-executor.test.ts

@@ -1,5 +1,5 @@
 import { unsafeTestValue } from "../../../test-support/unsafe-test-value"
-const { describe, test, expect, mock } = require("bun:test")
+import { describe, test, expect, mock } from "bun:test"
 
 type ExecuteSync = typeof import("./sync-executor").executeSync
 
@@ -13,6 +13,7 @@ type PromptAsyncInput = {
     variant?: string
     temperature?: number
     topP?: number
+    maxOutputTokens?: number
     options?: Record<string, unknown>
   }
 }
@@ -342,6 +343,64 @@ describe("executeSync", () => {
     expect(deps.setSessionFallbackChain).toHaveBeenCalledWith("ses-fallback", fallbackChain)
   })
 
+  test("registers child-session bootstrap and tracked prompt state before sync prompt dispatch", async () => {
+    //#given
+    const executeSync = await importExecuteSync()
+    const { _resetForTesting, getSessionAgent } = require("../../features/claude-code-session-state")
+    const { clearAllDelegatedChildSessionBootstrap, getDelegatedChildSessionBootstrap } = require("../../shared/delegated-child-session-bootstrap")
+    const { clearSessionTools, getSessionTools } = require("../../shared/session-tools-store")
+    const deps = createDependencies({
+      createOrGetSession: mock(async () => ({ sessionID: "ses-call-bootstrap", isNew: true })),
+    })
+    const toolContext = createToolContext()
+    const observed: Array<{
+      agent: string | undefined
+      tools: Record<string, boolean> | undefined
+      bootstrap: ReturnType<typeof getDelegatedChildSessionBootstrap>
+    }> = []
+    const recorder = createPromptAsyncRecorder(async () => {
+      observed.push({
+        agent: getSessionAgent("ses-call-bootstrap"),
+        tools: getSessionTools("ses-call-bootstrap"),
+        bootstrap: getDelegatedChildSessionBootstrap("ses-call-bootstrap"),
+      })
+      return { data: {} }
+    })
+    const args = {
+      subagent_type: "explore",
+      description: "bootstrap state",
+      prompt: "collect bootstrap evidence",
+      run_in_background: false,
+    }
+    const fallbackChain = [
+      { providers: ["openai"], model: "gpt-5.4", variant: "high" },
+    ]
+
+    try {
+      //#when
+      await executeSync(
+        args,
+        toolContext,
+        createContext(recorder.promptAsync) as never,
+        deps,
+        fallbackChain
+      )
+
+      //#then
+      expect(observed[0]?.agent).toBe("explore")
+      expect(observed[0]?.tools?.question).toBe(false)
+      expect(observed[0]?.tools?.task).toBe(false)
+      expect(observed[0]?.bootstrap?.retryParts[0]?.text).toContain("collect bootstrap evidence")
+      expect(observed[0]?.bootstrap?.tools?.question).toBe(false)
+      expect(observed[0]?.bootstrap?.fallbackChain?.[0]?.model).toBe("gpt-5.4")
+      expect(getDelegatedChildSessionBootstrap("ses-call-bootstrap")).toBeUndefined()
+    } finally {
+      clearAllDelegatedChildSessionBootstrap()
+      clearSessionTools()
+      _resetForTesting()
+    }
+  })
+
   test("returns dedicated agent-not-found error with task metadata", async () => {
     //#given
     const executeSync = await importExecuteSync()

src/tools/call-omo-agent/sync-executor.ts

@@ -1,15 +1,20 @@
-import type { CallOmoAgentArgs } from "./types"
 import type { PluginInput } from "@opencode-ai/plugin"
-import { subagentSessions, syncSubagentSessions } from "../../features/claude-code-session-state"
-import { getAgentToolRestrictions, log } from "../../shared"
-import { applySessionPromptParams } from "../../shared/session-prompt-params-helpers"
-import type { DelegatedModelConfig } from "../../shared/model-resolution-types"
-import type { FallbackEntry } from "../../shared/model-requirements"
-import { getAgentDisplayName, stripAgentListSortPrefix } from "../../shared/agent-display-names"
+import { setSessionAgent, subagentSessions, syncSubagentSessions } from "../../features/claude-code-session-state"
 import { promptAsyncAfterSessionIdle } from "../../hooks/shared/prompt-async-gate"
+import { getAgentToolRestrictions, log } from "../../shared"
+import { getAgentDisplayName, stripAgentListSortPrefix } from "../../shared/agent-display-names"
+import {
+  clearDelegatedChildSessionBootstrap,
+  registerDelegatedChildSessionBootstrap,
+} from "../../shared/delegated-child-session-bootstrap"
+import type { FallbackEntry } from "../../shared/model-requirements"
+import type { DelegatedModelConfig } from "../../shared/model-resolution-types"
+import { applySessionPromptParams } from "../../shared/session-prompt-params-helpers"
+import { deleteSessionTools, setSessionTools } from "../../shared/session-tools-store"
 import { waitForCompletion } from "./completion-poller"
 import { processMessages } from "./message-processor"
 import { createOrGetSession } from "./session-creator"
+import type { CallOmoAgentArgs } from "./types"
 
 type SessionWithPromptAsync = {
   promptAsync: (opts: { path: { id: string }; body: Record<string, unknown> }) => Promise<unknown>
@@ -58,6 +63,14 @@ function buildPromptGenerationParams(model: DelegatedModelConfig | undefined): R
   }
 }
 
+function buildSyncPromptTools(agent: string): Record<string, boolean> {
+  return {
+    ...getAgentToolRestrictions(agent),
+    task: false,
+    question: false,
+  }
+}
+
 export async function executeSync(
   args: CallOmoAgentArgs,
   toolContext: {
@@ -105,6 +118,16 @@ export async function executeSync(
     log(`[call_omo_agent] Sending prompt to session ${sessionID}`)
     log(`[call_omo_agent] Prompt text:`, args.prompt.substring(0, 100))
     const normalizedSubagentType = stripAgentListSortPrefix(args.subagent_type)
+    const promptAgent = getAgentDisplayName(normalizedSubagentType)
+    const promptTools = buildSyncPromptTools(normalizedSubagentType)
+    setSessionAgent(sessionID, promptAgent)
+    setSessionTools(sessionID, promptTools)
+    registerDelegatedChildSessionBootstrap({
+      sessionID,
+      promptText: args.prompt,
+      fallbackChain,
+      tools: promptTools,
+    })
 
     try {
       if (!hasPromptAsync(ctx.client.session)) {
@@ -119,12 +142,8 @@ export async function executeSync(
         input: {
           path: { id: sessionID },
           body: {
-            agent: getAgentDisplayName(normalizedSubagentType),
-            tools: {
-              ...getAgentToolRestrictions(normalizedSubagentType),
-              task: false,
-              question: false,
-            },
+            agent: promptAgent,
+            tools: promptTools,
             parts: [{ type: "text", text: args.prompt }],
             ...(model ? { model: { providerID: model.providerID, modelID: model.modelID } } : {}),
             ...(model?.variant ? { variant: model.variant } : {}),
@@ -160,9 +179,14 @@ export async function executeSync(
       deps.clearSessionFallbackChain(sessionID)
     }
 
+    if (sessionID) {
+      clearDelegatedChildSessionBootstrap(sessionID)
+    }
+
     if (sessionID && createdSessionForExecution) {
       subagentSessions.delete(sessionID)
       syncSubagentSessions.delete(sessionID)
+      deleteSessionTools(sessionID)
     }
   }
 }

src/tools/delegate-task/sync-prompt-sender.ts

@@ -1,18 +1,18 @@
-import type { DelegateTaskArgs, OpencodeClient, DelegatedModelConfig } from "./types"
 import type { SisyphusAgentConfig } from "../../config/schema"
-import { isPlanFamily } from "./constants"
-import { buildTaskPrompt } from "./prompt-builder"
+import { stripInvisibleAgentCharacters } from "../../shared/agent-display-names"
+import { getAgentToolRestrictions } from "../../shared/agent-tool-restrictions"
+import { createInternalAgentTextPart } from "../../shared/internal-initiator-marker"
 import {
   promptSyncWithModelSuggestionRetry,
   promptWithModelSuggestionRetry,
 } from "../../shared/model-suggestion-retry"
-import { routePromptRetry, routePromptSyncRetry } from "../../shared/session-route"
-import { formatDetailedError } from "./error-formatting"
-import { getAgentToolRestrictions } from "../../shared/agent-tool-restrictions"
-import { stripInvisibleAgentCharacters } from "../../shared/agent-display-names"
 import { applySessionPromptParams } from "../../shared/session-prompt-params-helpers"
+import { routePromptRetry, routePromptSyncRetry } from "../../shared/session-route"
 import { setSessionTools } from "../../shared/session-tools-store"
-import { createInternalAgentTextPart } from "../../shared/internal-initiator-marker"
+import { isPlanFamily } from "./constants"
+import { formatDetailedError } from "./error-formatting"
+import { buildTaskPrompt } from "./prompt-builder"
+import type { DelegatedModelConfig, DelegateTaskArgs, OpencodeClient } from "./types"
 
 type SendSyncPromptDeps = {
   promptWithModelSuggestionRetry: typeof promptWithModelSuggestionRetry
@@ -52,6 +52,15 @@ function isUnexpectedEofError(error: unknown): boolean {
   return lowered.includes("unexpected eof") || lowered.includes("json parse error")
 }
 
+export function buildSyncPromptTools(agentToUse: string): Record<string, boolean> {
+  return {
+    task: isPlanFamily(agentToUse),
+    call_omo_agent: true,
+    question: false,
+    ...getAgentToolRestrictions(agentToUse),
+  }
+}
+
 export async function sendSyncPrompt(
   client: OpencodeClient,
   input: {
@@ -67,15 +76,9 @@ export async function sendSyncPrompt(
   },
   deps: SendSyncPromptDeps = sendSyncPromptDeps
 ): Promise<string | null> {
-  const allowTask = isPlanFamily(input.agentToUse)
   const tddEnabled = input.sisyphusAgentConfig?.tdd
   const effectivePrompt = buildTaskPrompt(input.args.prompt, input.agentToUse, tddEnabled)
-  const tools = {
-    task: allowTask,
-    call_omo_agent: true,
-    question: false,
-    ...getAgentToolRestrictions(input.agentToUse),
-  }
+  const tools = buildSyncPromptTools(input.agentToUse)
   setSessionTools(input.sessionID, tools)
 
   applySessionPromptParams(input.sessionID, input.categoryModel)

src/tools/delegate-task/sync-task.test.ts

@@ -1,4 +1,4 @@
-const { describe, test, expect, beforeEach, afterEach, mock, spyOn } = require("bun:test")
+import { describe, test, expect, beforeEach, afterEach, mock, spyOn } from "bun:test"
 
 function clearRequireCache(modulePath: string): void {
   const resolvedPath = require.resolve(modulePath)
@@ -27,6 +27,8 @@ describe("executeSyncTask - cleanup on error paths", () => {
     addTaskCalls = []
     deleteCalls = []
     addCalls = []
+    const { clearAllDelegatedChildSessionBootstrap } = require("../../shared/delegated-child-session-bootstrap")
+    clearAllDelegatedChildSessionBootstrap()
 
     clearRequireCache("./sync-task")
 
@@ -62,6 +64,8 @@ describe("executeSyncTask - cleanup on error paths", () => {
     mock.restore()
     resetToastManager?.()
     resetToastManager = null
+    const { clearAllDelegatedChildSessionBootstrap } = require("../../shared/delegated-child-session-bootstrap")
+    clearAllDelegatedChildSessionBootstrap()
   })
 
   test("cleans up toast and subagentSessions when fetchSyncResult returns ok: false", async () => {
@@ -664,6 +668,69 @@ describe("executeSyncTask - cleanup on error paths", () => {
     })
   })
 
+  test("registers child-session bootstrap before sync prompt and clears it after completion", async () => {
+    const mockClient = {
+      session: {
+        create: async () => ({ data: { id: "ignored" } }),
+      },
+    }
+
+    const { executeSyncTask } = require("./sync-task")
+    const { getDelegatedChildSessionBootstrap } = require("../../shared/delegated-child-session-bootstrap")
+    const observedBootstrapPrompts: string[] = []
+    const observedBootstrapSystems: Array<string | undefined> = []
+    const observedBootstrapTools: Array<Record<string, boolean> | undefined> = []
+
+    const deps = {
+      createSyncSession: async () => ({ ok: true as const, sessionID: "ses_bootstrap_sync" }),
+      sendSyncPrompt: async (_client: unknown, input: { sessionID: string }) => {
+        const bootstrap = getDelegatedChildSessionBootstrap(input.sessionID)
+        observedBootstrapPrompts.push(bootstrap?.retryParts[0]?.text ?? "")
+        observedBootstrapSystems.push(bootstrap?.system)
+        observedBootstrapTools.push(bootstrap?.tools)
+        return null
+      },
+      pollSyncSession: async () => null,
+      fetchSyncResult: async () => ({ ok: true as const, textContent: "sync result" }),
+    }
+
+    const mockCtx = {
+      sessionID: "parent-session",
+      callID: "call-123",
+      metadata: () => {},
+    }
+
+    const mockExecutorCtx = {
+      client: mockClient,
+      directory: "/tmp",
+      onSyncSessionCreated: null,
+      modelFallbackControllerAccessor: {
+        setSessionFallbackChain: () => {},
+        clearSessionFallbackChain: () => {},
+      },
+    }
+
+    const args = {
+      prompt: "sync bootstrap prompt",
+      description: "sync bootstrap task",
+      category: "quick",
+      load_skills: [],
+      run_in_background: false,
+      command: null,
+    }
+
+    const result = await executeSyncTask(args, mockCtx, mockExecutorCtx, {
+      sessionID: "parent-session",
+    }, "sisyphus-junior", undefined, "sync delegated skill system", undefined, undefined, deps)
+
+    expect(result).toContain("sync result")
+    expect(observedBootstrapPrompts[0]).toContain("sync bootstrap prompt")
+    expect(observedBootstrapSystems[0]).toBe("sync delegated skill system")
+    expect(observedBootstrapTools[0]?.question).toBe(false)
+    expect(observedBootstrapTools[0]?.call_omo_agent).toBe(true)
+    expect(getDelegatedChildSessionBootstrap("ses_bootstrap_sync")).toBeUndefined()
+  })
+
   test("replays sync session side effects for retry-created sessions", async () => {
     const mockClient = {
       session: {

src/tools/delegate-task/sync-task.ts

@@ -1,19 +1,25 @@
-import type { ModelFallbackInfo } from "../../features/task-toast-manager/types"
-import type { DelegateTaskArgs, ToolContextWithMetadata, DelegatedModelConfig } from "./types"
-import type { ExecutorContext, ParentContext } from "./executor-types"
+import { setSessionAgent, subagentSessions, syncSubagentSessions } from "../../features/claude-code-session-state"
 import { getTaskToastManager } from "../../features/task-toast-manager"
+import type { ModelFallbackInfo } from "../../features/task-toast-manager/types"
 import { publishToolMetadata } from "../../features/tool-metadata-store"
-import { subagentSessions, syncSubagentSessions, setSessionAgent } from "../../features/claude-code-session-state"
-import { log } from "../../shared/logger"
-import { SessionCategoryRegistry } from "../../shared/session-category-registry"
-import { formatDuration } from "./time-formatter"
-import { formatDetailedError } from "./error-formatting"
-import { syncTaskDeps, type SyncTaskDeps } from "./sync-task-deps"
-import { getNextSyncFallbackModel, retrySyncPromptWithFallbacks } from "./sync-task-fallback"
 import { buildTaskMetadataBlock } from "../../features/tool-metadata-store/task-metadata-contract"
-import { resolveMetadataModel } from "./resolve-metadata-model"
-import { shouldRetryError } from "../../shared/model-error-classifier"
 import type { ModelFallbackState } from "../../hooks/model-fallback/hook"
+import {
+  clearDelegatedChildSessionBootstrap,
+  registerDelegatedChildSessionBootstrap,
+} from "../../shared/delegated-child-session-bootstrap"
+import { log } from "../../shared/logger"
+import { shouldRetryError } from "../../shared/model-error-classifier"
+import { SessionCategoryRegistry } from "../../shared/session-category-registry"
+import { formatDetailedError } from "./error-formatting"
+import type { ExecutorContext, ParentContext } from "./executor-types"
+import { buildTaskPrompt } from "./prompt-builder"
+import { resolveMetadataModel } from "./resolve-metadata-model"
+import { buildSyncPromptTools } from "./sync-prompt-sender"
+import { type SyncTaskDeps, syncTaskDeps } from "./sync-task-deps"
+import { getNextSyncFallbackModel, retrySyncPromptWithFallbacks } from "./sync-task-fallback"
+import { formatDuration } from "./time-formatter"
+import type { DelegatedModelConfig, DelegateTaskArgs, ToolContextWithMetadata } from "./types"
 
 function shouldAttemptPollErrorRecovery(pollError: string): boolean {
   const trimmed = pollError.trim()
@@ -107,11 +113,15 @@ export async function executeSyncTask(
       subagentSessions.add(newSessionID)
       syncSubagentSessions.add(newSessionID)
       setSessionAgent(newSessionID, agentToUse)
-      executorCtx.modelFallbackControllerAccessor?.setSessionFallbackChain(newSessionID, fallbackChain)
-
-      if (args.category) {
-        SessionCategoryRegistry.register(newSessionID, args.category)
-      }
+      registerDelegatedChildSessionBootstrap({
+        sessionID: newSessionID,
+        promptText: buildTaskPrompt(args.prompt, agentToUse, executorCtx.sisyphusAgentConfig?.tdd),
+        fallbackChain,
+        category: args.category,
+        system: systemContent,
+        tools: buildSyncPromptTools(agentToUse),
+        modelFallbackControllerAccessor: executorCtx.modelFallbackControllerAccessor,
+      })
 
       if (onSyncSessionCreated) {
         log("[task] Invoking onSyncSessionCreated callback", { sessionID: newSessionID, parentID: parentContext.sessionID })
@@ -131,7 +141,6 @@ export async function executeSyncTask(
     const publishSyncMetadata = async (
       currentSessionID: string,
       currentModel: DelegatedModelConfig | undefined,
-      currentTaskId: string,
       spawnDepth: number,
     ): Promise<void> => {
       await publishToolMetadata(ctx, {
@@ -171,7 +180,7 @@ export async function executeSyncTask(
         modelInfo,
       })
     }
-    await publishSyncMetadata(sessionID, categoryModel, taskId, spawnContext.childDepth)
+    await publishSyncMetadata(sessionID, categoryModel, spawnContext.childDepth)
 
     const syncPromptInput = {
       sessionID,
@@ -199,6 +208,7 @@ export async function executeSyncTask(
     const cleanupRetrySession = (currentSessionID: string): void => {
       subagentSessions.delete(currentSessionID)
       syncSubagentSessions.delete(currentSessionID)
+      clearDelegatedChildSessionBootstrap(currentSessionID)
       executorCtx.modelFallbackControllerAccessor?.clearSessionFallbackChain(currentSessionID)
       SessionCategoryRegistry.remove(currentSessionID)
     }
@@ -304,7 +314,7 @@ export async function executeSyncTask(
             })
           }
           if (taskId) {
-            await publishSyncMetadata(activeSessionID, effectiveCategoryModel, taskId, spawnContext.childDepth)
+            await publishSyncMetadata(activeSessionID, effectiveCategoryModel, spawnContext.childDepth)
           }
           continue
         }
@@ -329,7 +339,7 @@ export async function executeSyncTask(
         modelRoutingNote = `\nModel: ${actualModelStr}${args.category ? ` (category: ${args.category})` : ""}`
       }
 
-      await publishSyncMetadata(activeSessionID, effectiveCategoryModel, taskId!, spawnContext.childDepth)
+      await publishSyncMetadata(activeSessionID, effectiveCategoryModel, spawnContext.childDepth)
 
       return `Task completed in ${duration}.
 
@@ -364,6 +374,7 @@ ${buildTaskMetadataBlock({
     if (syncSessionID) {
       subagentSessions.delete(syncSessionID)
       syncSubagentSessions.delete(syncSessionID)
+      clearDelegatedChildSessionBootstrap(syncSessionID)
       executorCtx.modelFallbackControllerAccessor?.clearSessionFallbackChain(syncSessionID)
       SessionCategoryRegistry.remove(syncSessionID)
     }