refactor(background-agent): dedupe manager prompt cleanup paths

Add targeted regression coverage for pending parent bookkeeping and launch/resume prompt failure behavior before extracting narrow helper methods inside BackgroundManager.

Keep launch-only skill content and missing-agent formatting explicit, keep resume on direct promptAsync semantics, and reuse shared helper paths for pending registration, prompt body construction, and prompt-dispatch cleanup.

Co-authored-by: Codex <noreply@openai.com>

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

@@ -1572,6 +1572,189 @@ describe("BackgroundManager.trackTask", () => {
   })
 })
 
+describe("BackgroundManager.launch and resume cleanup regressions", () => {
+  test("launch should register pending task under parent before background start finishes", async () => {
+    //#given
+    let releaseCreate: (() => void) | undefined
+    const createGate = new Promise<void>((resolve) => {
+      releaseCreate = resolve
+    })
+    const client = {
+      session: {
+        get: async () => ({ data: { directory: "/test/dir" } }),
+        create: async () => {
+          await createGate
+          return { data: { id: "session-launch-pending" } }
+        },
+        promptAsync: async () => ({}),
+        abort: async () => ({}),
+      },
+    }
+    const manager = new BackgroundManager({ client, directory: tmpdir() } as unknown as PluginInput)
+
+    //#when
+    const task = await manager.launch({
+      description: "pending registration",
+      prompt: "launch prompt",
+      agent: "explore",
+      parentSessionID: "parent-launch-pending",
+      parentMessageID: "msg-launch-pending",
+    })
+
+    //#then
+    expect(getPendingByParent(manager).get("parent-launch-pending")?.has(task.id)).toBe(true)
+    expect(manager.getTask(task.id)?.status).toBe("pending")
+
+    releaseCreate?.()
+    await flushBackgroundNotifications()
+    manager.shutdown()
+  })
+
+  test("launch should clean pending bookkeeping and format missing-agent prompt errors", async () => {
+    //#given
+    const abortedSessionIDs: string[] = []
+    const promptAsyncCalls: string[] = []
+    const client = {
+      session: {
+        get: async () => ({ data: { directory: "/test/dir" } }),
+        create: async () => ({ data: { id: "session-launch-error" } }),
+        promptAsync: async (args: { path: { id: string } }) => {
+          promptAsyncCalls.push(args.path.id)
+          if (args.path.id === "session-launch-error") {
+            throw new Error("agent.name is undefined")
+          }
+          return {}
+        },
+        abort: async (args: { path: { id: string } }) => {
+          abortedSessionIDs.push(args.path.id)
+          return {}
+        },
+        messages: async () => ({ data: [] }),
+      },
+    }
+    const manager = new BackgroundManager({ client, directory: tmpdir() } as unknown as PluginInput)
+
+    //#when
+    const launchedTask = await manager.launch({
+      description: "launch prompt error",
+      prompt: "launch prompt",
+      agent: "missing-agent",
+      parentSessionID: "parent-launch-error",
+      parentMessageID: "msg-launch-error",
+    })
+    await flushBackgroundNotifications()
+    await new Promise((resolve) => setTimeout(resolve, 10))
+
+    //#then
+    const storedTask = manager.getTask(launchedTask.id)
+    expect(storedTask?.status).toBe("interrupt")
+    expect(storedTask?.error).toBe('Agent "missing-agent" not found. Make sure the agent is registered in your opencode.json or provided by a plugin.')
+    expect(storedTask?.concurrencyKey).toBeUndefined()
+    expect(storedTask?.completedAt).toBeInstanceOf(Date)
+    expect(getPendingByParent(manager).get("parent-launch-error")).toBeUndefined()
+    expect(abortedSessionIDs).toContain("session-launch-error")
+    expect(promptAsyncCalls).toContain("parent-launch-error")
+
+    manager.shutdown()
+  })
+
+  test("resume should clean pending bookkeeping and preserve raw prompt errors", async () => {
+    //#given
+    const abortedSessionIDs: string[] = []
+    const promptAsyncCalls: string[] = []
+    const client = {
+      session: {
+        promptAsync: async (args: { path: { id: string } }) => {
+          promptAsyncCalls.push(args.path.id)
+          if (args.path.id === "session-resume-error") {
+            throw new Error("resume prompt exploded")
+          }
+          return {}
+        },
+        abort: async (args: { path: { id: string } }) => {
+          abortedSessionIDs.push(args.path.id)
+          return {}
+        },
+        messages: async () => ({ data: [] }),
+      },
+    }
+    const manager = new BackgroundManager({ client, directory: tmpdir() } as unknown as PluginInput)
+    const task: BackgroundTask = {
+      id: "task-resume-error",
+      sessionID: "session-resume-error",
+      parentSessionID: "parent-before-resume-error",
+      parentMessageID: "msg-before-resume-error",
+      description: "resume prompt error",
+      prompt: "resume prompt",
+      agent: "explore",
+      status: "completed",
+      startedAt: new Date(),
+      completedAt: new Date(),
+      concurrencyGroup: "explore",
+    }
+    getTaskMap(manager).set(task.id, task)
+
+    //#when
+    await manager.resume({
+      sessionId: "session-resume-error",
+      prompt: "resume now",
+      parentSessionID: "parent-resume-error",
+      parentMessageID: "msg-resume-error",
+    })
+    await flushBackgroundNotifications()
+    await new Promise((resolve) => setTimeout(resolve, 10))
+
+    //#then
+    expect(task.status).toBe("interrupt")
+    expect(task.error).toBe("resume prompt exploded")
+    expect(task.concurrencyKey).toBeUndefined()
+    expect(task.completedAt).toBeInstanceOf(Date)
+    expect(getPendingByParent(manager).get("parent-resume-error")).toBeUndefined()
+    expect(abortedSessionIDs).toContain("session-resume-error")
+    expect(promptAsyncCalls).toContain("parent-resume-error")
+
+    manager.shutdown()
+  })
+
+  test("trackTask should move pending bookkeeping when parent session changes", async () => {
+    //#given
+    const manager = createBackgroundManager()
+    stubNotifyParentSession(manager)
+    const existingTask: BackgroundTask = {
+      id: "task-parent-move",
+      sessionID: "session-parent-move",
+      parentSessionID: "parent-before-move",
+      parentMessageID: "msg-before-move",
+      description: "tracked external task",
+      prompt: "",
+      agent: "task",
+      status: "running",
+      startedAt: new Date(),
+      progress: {
+        toolCalls: 0,
+        lastUpdate: new Date(),
+      },
+    }
+    getTaskMap(manager).set(existingTask.id, existingTask)
+    getPendingByParent(manager).set("parent-before-move", new Set([existingTask.id]))
+
+    //#when
+    await manager.trackTask({
+      taskId: existingTask.id,
+      sessionID: existingTask.sessionID!,
+      parentSessionID: "parent-after-move",
+      description: existingTask.description,
+      agent: existingTask.agent,
+    })
+
+    //#then
+    expect(getPendingByParent(manager).get("parent-before-move")).toBeUndefined()
+    expect(getPendingByParent(manager).get("parent-after-move")?.has(existingTask.id)).toBe(true)
+
+    manager.shutdown()
+  })
+})
+
 describe("BackgroundManager.resume concurrency key", () => {
   let manager: BackgroundManager
 

src/features/background-agent/manager.ts

@@ -291,11 +291,7 @@ export class BackgroundManager {
       this.taskHistory.record(input.parentSessionID, { id: task.id, agent: input.agent, description: input.description, status: "pending", category: input.category })
 
       // Track for batched notifications immediately (pending state)
-      if (input.parentSessionID) {
-        const pending = this.pendingByParent.get(input.parentSessionID) ?? new Set()
-        pending.add(task.id)
-        this.pendingByParent.set(input.parentSessionID, pending)
-      }
+      this.registerPendingTaskForParent(input.parentSessionID, task.id)
 
       // Add to queue
       const key = this.getConcurrencyKeyFromInput(input)
@@ -481,59 +477,21 @@ export class BackgroundManager {
     // Include model if caller provided one (e.g., from Sisyphus category configs)
     // IMPORTANT: variant must be a top-level field in the body, NOT nested inside model
     // OpenCode's PromptInput schema expects: { model: { providerID, modelID }, variant: "max" }
-    const launchModel = input.model
-      ? { providerID: input.model.providerID, modelID: input.model.modelID }
-      : undefined
-    const launchVariant = input.model?.variant
-
     promptWithModelSuggestionRetry(this.client, {
       path: { id: sessionID },
-      body: {
+      body: this.buildTaskPromptBody({
+        sessionID,
         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),
-          }
-          setSessionTools(sessionID, tools)
-          return tools
-        })(),
-        parts: [createInternalAgentTextPart(input.prompt)],
-      },
+        model: input.model,
+        skillContent: input.skillContent,
+        prompt: input.prompt,
+      }),
     }).catch((error) => {
-      log("[background-agent] promptAsync error:", error)
-      const existingTask = this.findBySession(sessionID)
-      if (existingTask) {
-        existingTask.status = "interrupt"
-        const errorMessage = error instanceof Error ? error.message : String(error)
-        if (errorMessage.includes("agent.name") || errorMessage.includes("undefined")) {
-          existingTask.error = `Agent "${input.agent}" not found. Make sure the agent is registered in your opencode.json or provided by a plugin.`
-        } else {
-          existingTask.error = errorMessage
-        }
-        existingTask.completedAt = new Date()
-        if (existingTask.concurrencyKey) {
-          this.concurrencyManager.release(existingTask.concurrencyKey)
-          existingTask.concurrencyKey = undefined
-        }
-
-        removeTaskToastTracking(existingTask.id)
-
-        // Abort the session to prevent infinite polling hang
-        this.client.session.abort({
-          path: { id: sessionID },
-        }).catch(() => {})
-
-        this.markForNotification(existingTask)
-        this.enqueueNotificationForParent(existingTask.parentSessionID, () => this.notifyParentSession(existingTask)).catch(err => {
-          log("[background-agent] Failed to notify on error:", err)
-        })
-      }
+      this.handlePromptDispatchError(task, error, {
+        agentName: input.agent,
+        errorLogLabel: "[background-agent] promptAsync error:",
+        notifyLogLabel: "[background-agent] Failed to notify on error:",
+      })
     })
   }
 
@@ -582,6 +540,95 @@ export class BackgroundManager {
     return input.agent
   }
 
+  private registerPendingTaskForParent(parentSessionID: string | undefined, taskId: string): void {
+    if (!parentSessionID) {
+      return
+    }
+
+    const pending = this.pendingByParent.get(parentSessionID) ?? new Set<string>()
+    pending.add(taskId)
+    this.pendingByParent.set(parentSessionID, pending)
+  }
+
+  private buildTaskPromptTools(sessionID: string, agent: string): Record<string, boolean> {
+    const tools = {
+      task: false,
+      call_omo_agent: true,
+      question: false,
+      ...getAgentToolRestrictions(agent),
+    }
+    setSessionTools(sessionID, tools)
+    return tools
+  }
+
+  private buildTaskPromptBody(options: {
+    sessionID: string
+    agent: string
+    model?: BackgroundTask["model"]
+    skillContent?: string
+    prompt: string
+  }): {
+    agent: string
+    model?: { providerID: string; modelID: string }
+    variant?: string
+    system?: string
+    tools: Record<string, boolean>
+    parts: ReturnType<typeof createInternalAgentTextPart>[]
+  } {
+    const model = options.model
+      ? { providerID: options.model.providerID, modelID: options.model.modelID }
+      : undefined
+    const variant = options.model?.variant
+
+    return {
+      agent: options.agent,
+      ...(model ? { model } : {}),
+      ...(variant ? { variant } : {}),
+      ...(options.skillContent ? { system: options.skillContent } : {}),
+      tools: this.buildTaskPromptTools(options.sessionID, options.agent),
+      parts: [createInternalAgentTextPart(options.prompt)],
+    }
+  }
+
+  private handlePromptDispatchError(
+    task: BackgroundTask,
+    error: unknown,
+    options: {
+      agentName?: string
+      errorLogLabel: string
+      notifyLogLabel: string
+    }
+  ): void {
+    log(options.errorLogLabel, error)
+
+    task.status = "interrupt"
+    const errorMessage = error instanceof Error ? error.message : String(error)
+    if (options.agentName && (errorMessage.includes("agent.name") || errorMessage.includes("undefined"))) {
+      task.error = `Agent "${options.agentName}" not found. Make sure the agent is registered in your opencode.json or provided by a plugin.`
+    } else {
+      task.error = errorMessage
+    }
+    task.completedAt = new Date()
+
+    if (task.concurrencyKey) {
+      this.concurrencyManager.release(task.concurrencyKey)
+      task.concurrencyKey = undefined
+    }
+
+    removeTaskToastTracking(task.id)
+
+    if (task.sessionID) {
+      this.client.session.abort({
+        path: { id: task.sessionID },
+      }).catch(() => {})
+    }
+
+    this.markForNotification(task)
+    this.enqueueNotificationForParent(task.parentSessionID, () => this.notifyParentSession(task)).catch(err => {
+      log(options.notifyLogLabel, err)
+    })
+  }
+
   /**
    * Track a task created elsewhere (e.g., from task) for notification tracking.
    * This allows tasks created by other tools to receive the same toast/prompt notifications.
@@ -618,9 +665,7 @@ export class BackgroundManager {
 
       // Track for batched notifications if task is pending or running
       if (existingTask.status === "pending" || existingTask.status === "running") {
-        const pending = this.pendingByParent.get(input.parentSessionID) ?? new Set()
-        pending.add(existingTask.id)
-        this.pendingByParent.set(input.parentSessionID, pending)
+        this.registerPendingTaskForParent(input.parentSessionID, existingTask.id)
       } else if (!parentChanged) {
         // Only clean up if parent didn't change (already cleaned above if it did)
         this.cleanupPendingByParent(existingTask)
@@ -662,11 +707,7 @@ export class BackgroundManager {
     this.startPolling()
     this.taskHistory.record(input.parentSessionID, { id: task.id, sessionID: input.sessionID, agent: input.agent || "task", description: input.description, status: "running", startedAt: task.startedAt })
 
-    if (input.parentSessionID) {
-      const pending = this.pendingByParent.get(input.parentSessionID) ?? new Set()
-      pending.add(task.id)
-      this.pendingByParent.set(input.parentSessionID, pending)
-    }
+    this.registerPendingTaskForParent(input.parentSessionID, task.id)
 
     log("[background-agent] Registered external task:", { taskId: task.id, sessionID: input.sessionID })
 
@@ -728,11 +769,7 @@ export class BackgroundManager {
       subagentSessions.add(existingTask.sessionID)
     }
 
-    if (input.parentSessionID) {
-      const pending = this.pendingByParent.get(input.parentSessionID) ?? new Set()
-      pending.add(existingTask.id)
-      this.pendingByParent.set(input.parentSessionID, pending)
-    }
+    this.registerPendingTaskForParent(input.parentSessionID, existingTask.id)
 
     const toastManager = getTaskToastManager()
     if (toastManager) {
@@ -756,54 +793,18 @@ export class BackgroundManager {
     // Fire-and-forget prompt via promptAsync (no response body needed)
     // Include model if task has one (preserved from original launch with category config)
     // variant must be top-level in body, not nested inside model (OpenCode PromptInput schema)
-    const resumeModel = existingTask.model
-      ? { providerID: existingTask.model.providerID, modelID: existingTask.model.modelID }
-      : undefined
-    const resumeVariant = existingTask.model?.variant
-
     this.client.session.promptAsync({
       path: { id: existingTask.sessionID },
-      body: {
+      body: this.buildTaskPromptBody({
+        sessionID: existingTask.sessionID,
         agent: existingTask.agent,
-        ...(resumeModel ? { model: resumeModel } : {}),
-        ...(resumeVariant ? { variant: resumeVariant } : {}),
-        tools: (() => {
-          const tools = {
-            task: false,
-            call_omo_agent: true,
-            question: false,
-            ...getAgentToolRestrictions(existingTask.agent),
-          }
-          setSessionTools(existingTask.sessionID!, tools)
-          return tools
-        })(),
-        parts: [createInternalAgentTextPart(input.prompt)],
-      },
+        model: existingTask.model,
+        prompt: input.prompt,
+      }),
     }).catch((error) => {
-      log("[background-agent] resume prompt error:", error)
-      existingTask.status = "interrupt"
-      const errorMessage = error instanceof Error ? error.message : String(error)
-      existingTask.error = errorMessage
-      existingTask.completedAt = new Date()
-
-      // Release concurrency on error to prevent slot leaks
-      if (existingTask.concurrencyKey) {
-        this.concurrencyManager.release(existingTask.concurrencyKey)
-        existingTask.concurrencyKey = undefined
-      }
-
-      removeTaskToastTracking(existingTask.id)
-
-      // Abort the session to prevent infinite polling hang
-      if (existingTask.sessionID) {
-        this.client.session.abort({
-          path: { id: existingTask.sessionID },
-        }).catch(() => {})
-      }
-
-      this.markForNotification(existingTask)
-      this.enqueueNotificationForParent(existingTask.parentSessionID, () => this.notifyParentSession(existingTask)).catch(err => {
-        log("[background-agent] Failed to notify on resume error:", err)
+      this.handlePromptDispatchError(existingTask, error, {
+        errorLogLabel: "[background-agent] resume prompt error:",
+        notifyLogLabel: "[background-agent] Failed to notify on resume error:",
       })
     })