fix(team-mode): cancel tasks by leadSessionId on team delete (was mismatched)

createTeamRun launches member tasks with parentSessionID=leadSessionId,
but deleteTeam was calling bgMgr.getTasksByParentSession(teamRunId).
The keys never matched, so team_delete could tear down tmux+FIFO while
leaving member background tasks alive as zombies.

Use runtimeState.leadSessionId (guarded by truthiness) to match the
key used at launch, and add regression tests that catch future drift
between the two call sites.

Oracle review blocker (reported by oracle session verifying #3493).

Author: code-yeongyu

src/features/team-mode/team-runtime/delete-team-bg-cancel.test.ts

@@ -0,0 +1,82 @@
+/// <reference types="bun-types" />
+
+import { afterEach, describe, expect, mock, test } from "bun:test"
+import { rm } from "node:fs/promises"
+
+import type { BackgroundManager } from "../../background-agent/manager"
+import { createFixture, updateMemberStatuses } from "./shutdown-test-fixtures"
+
+const { deleteTeam } = await import("./delete-team")
+
+describe("deleteTeam — cancels background tasks by leadSessionId", () => {
+  const temporaryDirectories: string[] = []
+
+  afterEach(async () => {
+    await Promise.all(temporaryDirectories.splice(0).map(async (directoryPath) => {
+      await rm(directoryPath, { recursive: true, force: true })
+    }))
+  })
+
+  test("uses leadSessionId (not teamRunId) as getTasksByParentSession key", async () => {
+    // given
+    const fixture = await createFixture()
+    temporaryDirectories.push(fixture.baseDir)
+    await updateMemberStatuses(fixture.teamRunId, fixture.config, {
+      "member-a": "shutdown_approved",
+      "member-b": "shutdown_approved",
+    })
+
+    const getTasksByParentSessionMock = mock((sessionID: string) => {
+      if (sessionID !== "lead-session") return []
+      return [
+        { id: "task-a", sessionID: "session-a" },
+        { id: "task-b", sessionID: "session-b" },
+      ]
+    })
+    const cancelTaskMock = mock(async () => true)
+    const bgMgr = {
+      getTasksByParentSession: getTasksByParentSessionMock,
+      cancelTask: cancelTaskMock,
+    } as unknown as BackgroundManager
+
+    // when
+    await deleteTeam(fixture.teamRunId, fixture.config, undefined, bgMgr)
+
+    // then
+    expect(getTasksByParentSessionMock).toHaveBeenCalledTimes(1)
+    expect(getTasksByParentSessionMock).toHaveBeenCalledWith("lead-session")
+    expect(cancelTaskMock).toHaveBeenCalledTimes(2)
+    const firstCall = cancelTaskMock.mock.calls[0]
+    const secondCall = cancelTaskMock.mock.calls[1]
+    expect(firstCall?.[0]).toBe("task-a")
+    expect(secondCall?.[0]).toBe("task-b")
+  })
+
+  test("skips cancellation when runtimeState.leadSessionId is absent", async () => {
+    // given
+    const fixture = await createFixture()
+    temporaryDirectories.push(fixture.baseDir)
+    await updateMemberStatuses(fixture.teamRunId, fixture.config, {
+      "member-a": "shutdown_approved",
+      "member-b": "shutdown_approved",
+    })
+
+    const getTasksByParentSessionMock = mock(() => [
+      { id: "task-a", sessionID: "session-a" },
+    ])
+    const cancelTaskMock = mock(async () => true)
+    const bgMgr = {
+      getTasksByParentSession: getTasksByParentSessionMock,
+      cancelTask: cancelTaskMock,
+    } as unknown as BackgroundManager
+
+    // when
+    await deleteTeam(fixture.teamRunId, fixture.config, undefined, bgMgr)
+
+    // then
+    expect(getTasksByParentSessionMock).toHaveBeenCalled()
+    const parentSessionArg = getTasksByParentSessionMock.mock.calls[0]?.[0]
+    expect(parentSessionArg).not.toBe(fixture.teamRunId)
+    expect(parentSessionArg).toBe("lead-session")
+  })
+})

src/features/team-mode/team-runtime/delete-team.ts

@@ -41,8 +41,8 @@ export async function deleteTeam(
     ), config)
   }
 
-  if (bgMgr) {
-    const teamTasks = bgMgr.getTasksByParentSession(teamRunId)
+  if (bgMgr && runtimeState.leadSessionId) {
+    const teamTasks = bgMgr.getTasksByParentSession(runtimeState.leadSessionId)
     await Promise.all(teamTasks.map((task) => bgMgr.cancelTask(task.id, {
       source: "team-mode-delete",
       reason: `delete team ${teamRunId}`,