diff --git a/src/features/team-mode/team-runtime/shutdown-helpers.ts b/src/features/team-mode/team-runtime/shutdown-helpers.ts
new file mode 100644
index 000000000..49bbecdc1
--- /dev/null
+++ b/src/features/team-mode/team-runtime/shutdown-helpers.ts
@@ -0,0 +1,78 @@
+import { randomUUID } from "node:crypto"
+import { rm } from "node:fs/promises"
+
+import type { Message, RuntimeState } from "../types"
+
+export const DELETABLE_MEMBER_STATUSES = new Set<RuntimeState["members"][number]["status"]>([
+  "completed",
+  "shutdown_approved",
+  "errored",
+])
+
+export function createShutdownMessage(from: string, to: string, kind: Message["kind"], body: string): Message {
+  return {
+    version: 1,
+    messageId: randomUUID(),
+    from,
+    to,
+    kind,
+    body,
+    timestamp: Date.now(),
+  }
+}
+
+export function getRuntimeMember(runtimeState: RuntimeState, memberName: string): RuntimeState["members"][number] {
+  const member = runtimeState.members.find((candidate) => candidate.name === memberName)
+  if (!member) {
+    throw new Error(`unknown member '${memberName}'`)
+  }
+
+  return member
+}
+
+export function getLeadMemberName(runtimeState: RuntimeState): string {
+  const leadMember = runtimeState.members.find((member) => member.agentType === "leader")
+  if (!leadMember) {
+    throw new Error(`team '${runtimeState.teamRunId}' is missing a lead member`)
+  }
+
+  return leadMember.name
+}
+
+export function createSendContext(
+  runtimeState: RuntimeState,
+  senderName: string,
+): { isLead: boolean; activeMembers: string[] } {
+  const sender = getRuntimeMember(runtimeState, senderName)
+  return {
+    isLead: sender.agentType === "leader",
+    activeMembers: runtimeState.members.map((member) => member.name),
+  }
+}
+
+export function findLatestShutdownRequestIndex(
+  runtimeState: RuntimeState,
+  memberName: string,
+  requesterName?: string,
+): number {
+  for (let index = runtimeState.shutdownRequests.length - 1; index >= 0; index -= 1) {
+    const shutdownRequest = runtimeState.shutdownRequests[index]
+    if (shutdownRequest.memberId !== memberName) continue
+    if (requesterName !== undefined && shutdownRequest.requesterName !== requesterName) continue
+    return index
+  }
+
+  return -1
+}
+
+export async function removeWorktrees(memberPaths: Array<string | undefined>): Promise<string[]> {
+  const removedWorktrees: string[] = []
+
+  for (const memberPath of new Set(memberPaths)) {
+    if (!memberPath) continue
+    await rm(memberPath, { recursive: true, force: true })
+    removedWorktrees.push(memberPath)
+  }
+
+  return removedWorktrees
+}
diff --git a/src/features/team-mode/team-runtime/shutdown-test-fixtures.ts b/src/features/team-mode/team-runtime/shutdown-test-fixtures.ts
new file mode 100644
index 000000000..27b135aff
--- /dev/null
+++ b/src/features/team-mode/team-runtime/shutdown-test-fixtures.ts
@@ -0,0 +1,146 @@
+import { mkdir, mkdtemp, readdir, readFile } from "node:fs/promises"
+import { tmpdir } from "node:os"
+import path from "node:path"
+
+import { TeamModeConfigSchema } from "../../../config/schema/team-mode"
+import type { TeamModeConfig } from "../../../config/schema/team-mode"
+import { sendMessage } from "../team-mailbox/send"
+import { getInboxDir, getRuntimeStateDir, resolveBaseDir } from "../team-registry/paths"
+import { saveRuntimeState, transitionRuntimeState } from "../team-state-store/store"
+import { MessageSchema, type RuntimeState, type TeamSpec } from "../types"
+
+let fixtureCounter = 0
+
+function createUuid(sequence: number): string {
+  return `123e4567-e89b-42d3-a456-${sequence.toString(16).padStart(12, "0")}`
+}
+
+export function createConfig(baseDir: string): TeamModeConfig {
+  return TeamModeConfigSchema.parse({ base_dir: baseDir })
+}
+
+export function createSpec(worktreeRoot: string): TeamSpec {
+  fixtureCounter += 1
+
+  return {
+    version: 1,
+    name: `team-${fixtureCounter.toString(16).padStart(8, "0")}`,
+    createdAt: Date.now(),
+    leadAgentId: "lead",
+    members: [
+      { kind: "subagent_type", name: "lead", subagent_type: "sisyphus", backendType: "in-process", isActive: true },
+      {
+        kind: "category",
+        name: "member-a",
+        category: "deep",
+        prompt: "work on task a",
+        backendType: "in-process",
+        isActive: true,
+        worktreePath: path.join(worktreeRoot, "member-a"),
+      },
+      {
+        kind: "category",
+        name: "member-b",
+        category: "deep",
+        prompt: "work on task b",
+        backendType: "in-process",
+        isActive: true,
+        worktreePath: path.join(worktreeRoot, "member-b"),
+      },
+    ],
+  }
+}
+
+export async function createFixture(options?: { status?: RuntimeState["status"] }): Promise<{
+  baseDir: string
+  config: TeamModeConfig
+  teamRunId: string
+  worktreePaths: string[]
+}> {
+  fixtureCounter += 1
+  const baseDir = await mkdtemp(path.join(tmpdir(), `team-runtime-shutdown-${fixtureCounter}-`))
+  const config = createConfig(baseDir)
+  const worktreeRoot = path.join(baseDir, "fixture-worktrees")
+  const teamRunId = createUuid(fixtureCounter)
+  const runtimeState: RuntimeState = {
+    version: 1,
+    teamRunId,
+    teamName: createSpec(worktreeRoot).name,
+    specSource: "project",
+    createdAt: Date.now(),
+    status: options?.status ?? "active",
+    leadSessionId: "lead-session",
+    members: [
+      { name: "lead", agentType: "leader", status: "pending", pendingInjectedMessageIds: [] },
+      {
+        name: "member-a",
+        agentType: "general-purpose",
+        status: "pending",
+        pendingInjectedMessageIds: [],
+        worktreePath: path.join(worktreeRoot, "member-a"),
+      },
+      {
+        name: "member-b",
+        agentType: "general-purpose",
+        status: "pending",
+        pendingInjectedMessageIds: [],
+        worktreePath: path.join(worktreeRoot, "member-b"),
+      },
+    ],
+    shutdownRequests: [],
+    bounds: {
+      maxMembers: config.max_members,
+      maxParallelMembers: config.max_parallel_members,
+      maxMessagesPerRun: config.max_messages_per_run,
+      maxWallClockMinutes: config.max_wall_clock_minutes,
+      maxMemberTurns: config.max_member_turns,
+    },
+  }
+  await mkdir(getRuntimeStateDir(resolveBaseDir(config), teamRunId), { recursive: true })
+  await saveRuntimeState(runtimeState, config)
+
+  return {
+    baseDir,
+    config,
+    teamRunId: runtimeState.teamRunId,
+    worktreePaths: [path.join(worktreeRoot, "member-a"), path.join(worktreeRoot, "member-b")],
+  }
+}
+
+export async function updateMemberStatuses(
+  teamRunId: string,
+  config: TeamModeConfig,
+  statuses: Record<string, RuntimeState["members"][number]["status"]>,
+): Promise<void> {
+  await transitionRuntimeState(teamRunId, (runtimeState) => ({
+    ...runtimeState,
+    members: runtimeState.members.map((member) => ({
+      ...member,
+      status: statuses[member.name] ?? member.status,
+    })),
+  }), config)
+}
+
+export async function readInboxMessages(teamRunId: string, memberName: string, config: TeamModeConfig) {
+  const inboxDir = getInboxDir(resolveBaseDir(config), teamRunId, memberName)
+  const fileNames = (await readdir(inboxDir)).filter((entry) => entry.endsWith(".json")).sort()
+  return Promise.all(fileNames.map(async (fileName) => {
+    const content = await readFile(path.join(inboxDir, fileName), "utf8")
+    return MessageSchema.parse(JSON.parse(content))
+  }))
+}
+
+export function createTestMessage(overrides?: Partial<Parameters<typeof sendMessage>[0]>) {
+  fixtureCounter += 1
+
+  return MessageSchema.parse({
+    version: 1,
+    messageId: createUuid(fixtureCounter),
+    from: "lead",
+    to: "member-a",
+    kind: "message",
+    body: "hello",
+    timestamp: Date.now(),
+    ...overrides,
+  })
+}
diff --git a/src/features/team-mode/team-runtime/shutdown.test.ts b/src/features/team-mode/team-runtime/shutdown.test.ts
new file mode 100644
index 000000000..14b93f6fe
--- /dev/null
+++ b/src/features/team-mode/team-runtime/shutdown.test.ts
@@ -0,0 +1,396 @@
+/// <reference types="bun-types" />
+
+import { afterEach, describe, expect, mock, spyOn, test } from "bun:test"
+import { access, mkdir, rm } from "node:fs/promises"
+import path from "node:path"
+
+import { sendMessage } from "../team-mailbox/send"
+import { getRuntimeStateDir, resolveBaseDir } from "../team-registry/paths"
+import * as logger from "../../../shared/logger"
+import * as layoutModule from "../team-layout-tmux/layout"
+import * as runtimeStateStore from "../team-state-store/store"
+import { loadRuntimeState, transitionRuntimeState } from "../team-state-store/store"
+import {
+  createFixture,
+  createTestMessage,
+  readInboxMessages,
+  updateMemberStatuses,
+} from "./shutdown-test-fixtures"
+
+const { approveShutdown, deleteTeam, rejectShutdown, requestShutdownOfMember } = await import("./shutdown")
+
+describe("team-runtime shutdown", () => {
+  const temporaryDirectories: string[] = []
+
+  afterEach(async () => {
+    await Promise.all(temporaryDirectories.splice(0).map(async (directoryPath) => {
+      await rm(directoryPath, { recursive: true, force: true })
+    }))
+    mock.restore()
+  })
+
+  test("refuses team deletion while non-lead members are still active", async () => {
+    // given
+    const fixture = await createFixture()
+    temporaryDirectories.push(fixture.baseDir)
+    await updateMemberStatuses(fixture.teamRunId, fixture.config, {
+      "member-a": "running",
+      "member-b": "running",
+    })
+
+    // when
+    const result = deleteTeam(fixture.teamRunId, fixture.config)
+
+    // then
+    await result.then(
+      () => { throw new Error("expected deleteTeam to reject") },
+      (error: unknown) => {
+        if (!(error instanceof Error)) throw error
+        expect(error.message).toBe("members still active")
+      },
+    )
+    const runtimeState = await loadRuntimeState(fixture.teamRunId, fixture.config)
+    expect(runtimeState.status).toBe("active")
+    expect(runtimeState.members.filter((member) => member.agentType !== "leader").map((member) => member.status)).toEqual([
+      "running",
+      "running",
+    ])
+  })
+
+  test("writes shutdown requests to the target inbox and records runtime metadata", async () => {
+    // given
+    const fixture = await createFixture()
+    temporaryDirectories.push(fixture.baseDir)
+
+    // when
+    await requestShutdownOfMember(fixture.teamRunId, "member-a", "lead", fixture.config)
+
+    // then
+    const inboxMessages = await readInboxMessages(fixture.teamRunId, "member-a", fixture.config)
+    const runtimeState = await loadRuntimeState(fixture.teamRunId, fixture.config)
+    expect(inboxMessages).toHaveLength(1)
+    expect(inboxMessages[0]).toEqual(expect.objectContaining({
+      from: "lead",
+      to: "member-a",
+      kind: "shutdown_request",
+      body: "",
+    }))
+    expect(runtimeState.shutdownRequests).toEqual([
+      expect.objectContaining({
+        memberId: "member-a",
+        requesterName: "lead",
+        requestedAt: expect.any(Number),
+      }),
+    ])
+  })
+
+  test("approves shutdown requests and notifies the lead", async () => {
+    // given
+    const fixture = await createFixture()
+    temporaryDirectories.push(fixture.baseDir)
+    await requestShutdownOfMember(fixture.teamRunId, "member-a", "lead", fixture.config)
+
+    // when
+    await approveShutdown(fixture.teamRunId, "member-a", "member-a", fixture.config)
+
+    // then
+    const runtimeState = await loadRuntimeState(fixture.teamRunId, fixture.config)
+    const leadInboxMessages = await readInboxMessages(fixture.teamRunId, "lead", fixture.config)
+    const approvedRequest = runtimeState.shutdownRequests.find((shutdownRequest) => shutdownRequest.memberId === "member-a")
+    expect(approvedRequest?.approvedAt).toEqual(expect.any(Number))
+    expect(runtimeState.members.find((member) => member.name === "member-a")?.status).toBe("shutdown_approved")
+    expect(leadInboxMessages.some((message) => (
+      message.kind === "shutdown_approved"
+      && message.from === "member-a"
+      && message.to === "lead"
+      && message.body === "member-a"
+    ))).toBe(true)
+  })
+
+  test("rejects shutdown requests and replies to the original requester", async () => {
+    // given
+    const fixture = await createFixture()
+    temporaryDirectories.push(fixture.baseDir)
+    await requestShutdownOfMember(fixture.teamRunId, "member-a", "lead", fixture.config)
+
+    // when
+    await rejectShutdown(fixture.teamRunId, "member-a", "not done yet", fixture.config)
+
+    // then
+    const runtimeState = await loadRuntimeState(fixture.teamRunId, fixture.config)
+    const leadInboxMessages = await readInboxMessages(fixture.teamRunId, "lead", fixture.config)
+    const rejectedRequest = runtimeState.shutdownRequests.find((shutdownRequest) => shutdownRequest.memberId === "member-a")
+    expect(rejectedRequest).toEqual(expect.objectContaining({
+      rejectedAt: expect.any(Number),
+      rejectedReason: "not done yet",
+    }))
+    expect(leadInboxMessages.some((message) => (
+      message.kind === "shutdown_rejected"
+      && message.from === "member-a"
+      && message.to === "lead"
+      && message.body === "not done yet"
+    ))).toBe(true)
+  })
+
+  test("deletes team runtime resources after all non-lead members are approved", async () => {
+    // given
+    const fixture = await createFixture()
+    temporaryDirectories.push(fixture.baseDir)
+    await updateMemberStatuses(fixture.teamRunId, fixture.config, {
+      "member-a": "shutdown_approved",
+      "member-b": "shutdown_approved",
+    })
+    await Promise.all(fixture.worktreePaths.map(async (worktreePath) => {
+      await mkdir(worktreePath, { recursive: true })
+    }))
+    // when
+    const result = await deleteTeam(fixture.teamRunId, fixture.config)
+
+    // then
+    expect(result.removedLayout).toBe(false)
+    expect(result.removedWorktrees.sort()).toEqual([...fixture.worktreePaths].sort())
+    await Promise.all(fixture.worktreePaths.map(async (worktreePath) => {
+      await access(worktreePath).then(
+        () => { throw new Error(`expected ${worktreePath} to be removed`) },
+        () => undefined,
+      )
+    }))
+    const runtimeStateDirectory = getRuntimeStateDir(resolveBaseDir(fixture.config), fixture.teamRunId)
+    await access(runtimeStateDirectory).then(
+      () => { throw new Error(`expected ${runtimeStateDirectory} to be removed`) },
+      () => undefined,
+    )
+  })
+
+  test("deletes team even with active members when force=true", async () => {
+    // given
+    const fixture = await createFixture()
+    temporaryDirectories.push(fixture.baseDir)
+    await updateMemberStatuses(fixture.teamRunId, fixture.config, {
+      "member-a": "running",
+      "member-b": "running",
+    })
+    await Promise.all(fixture.worktreePaths.map(async (worktreePath) => {
+      await mkdir(worktreePath, { recursive: true })
+    }))
+
+    // when
+    const result = await deleteTeam(fixture.teamRunId, fixture.config, undefined, undefined, { force: true })
+
+    // then
+    expect(result.removedLayout).toBe(false)
+    expect(result.removedWorktrees.sort()).toEqual([...fixture.worktreePaths].sort())
+    await Promise.all(fixture.worktreePaths.map(async (worktreePath) => {
+      await access(worktreePath).then(
+        () => { throw new Error(`expected ${worktreePath} to be removed`) },
+        () => undefined,
+      )
+    }))
+    const runtimeStateDirectory = getRuntimeStateDir(resolveBaseDir(fixture.config), fixture.teamRunId)
+    await access(runtimeStateDirectory).then(
+      () => { throw new Error(`expected ${runtimeStateDirectory} to be removed`) },
+      () => undefined,
+    )
+  })
+
+  test("force deletes a team stuck in 'creating' status", async () => {
+    // given
+    const fixture = await createFixture({ status: "creating" })
+    temporaryDirectories.push(fixture.baseDir)
+    const transitionedStatuses: string[] = []
+    const originalTransitionRuntimeState = runtimeStateStore.transitionRuntimeState
+    spyOn(runtimeStateStore, "transitionRuntimeState").mockImplementation(async (teamRunId, transition, config) => {
+      const currentRuntimeState = await runtimeStateStore.loadRuntimeState(teamRunId, config)
+      transitionedStatuses.push(transition(currentRuntimeState).status)
+      return await originalTransitionRuntimeState(teamRunId, transition, config)
+    })
+    await updateMemberStatuses(fixture.teamRunId, fixture.config, {
+      "member-a": "pending",
+      "member-b": "pending",
+    })
+
+    // when
+    await deleteTeam(fixture.teamRunId, fixture.config, undefined, undefined, { force: true })
+
+    // then
+    expect(transitionedStatuses).toContain("deleted")
+    const runtimeStateDirectory = getRuntimeStateDir(resolveBaseDir(fixture.config), fixture.teamRunId)
+    await access(runtimeStateDirectory).then(
+      () => { throw new Error(`expected ${runtimeStateDirectory} to be removed`) },
+      () => undefined,
+    )
+  })
+
+  test("force deletes a team in 'orphaned' status", async () => {
+    // given
+    const fixture = await createFixture({ status: "orphaned" })
+    temporaryDirectories.push(fixture.baseDir)
+    const transitionedStatuses: string[] = []
+    const originalTransitionRuntimeState = runtimeStateStore.transitionRuntimeState
+    spyOn(runtimeStateStore, "transitionRuntimeState").mockImplementation(async (teamRunId, transition, config) => {
+      const currentRuntimeState = await runtimeStateStore.loadRuntimeState(teamRunId, config)
+      transitionedStatuses.push(transition(currentRuntimeState).status)
+      return await originalTransitionRuntimeState(teamRunId, transition, config)
+    })
+    await updateMemberStatuses(fixture.teamRunId, fixture.config, {
+      "member-a": "running",
+      "member-b": "running",
+    })
+
+    // when
+    await deleteTeam(fixture.teamRunId, fixture.config, undefined, undefined, { force: true })
+
+    // then
+    expect(transitionedStatuses).toContain("deleted")
+    const runtimeStateDirectory = getRuntimeStateDir(resolveBaseDir(fixture.config), fixture.teamRunId)
+    await access(runtimeStateDirectory).then(
+      () => { throw new Error(`expected ${runtimeStateDirectory} to be removed`) },
+      () => undefined,
+    )
+  })
+
+  test("force removes lead member worktree if present", async () => {
+    // given
+    const fixture = await createFixture()
+    temporaryDirectories.push(fixture.baseDir)
+    const leadWorktreePath = path.join(fixture.baseDir, "fixture-worktrees", "lead")
+    await transitionRuntimeState(fixture.teamRunId, (runtimeState) => ({
+      ...runtimeState,
+      members: runtimeState.members.map((member) => member.name === "lead"
+        ? { ...member, worktreePath: leadWorktreePath }
+        : member),
+    }), fixture.config)
+    await mkdir(leadWorktreePath, { recursive: true })
+    await Promise.all(fixture.worktreePaths.map(async (worktreePath) => {
+      await mkdir(worktreePath, { recursive: true })
+    }))
+    await updateMemberStatuses(fixture.teamRunId, fixture.config, {
+      "member-a": "running",
+      "member-b": "running",
+    })
+
+    // when
+    const result = await deleteTeam(fixture.teamRunId, fixture.config, undefined, undefined, { force: true })
+
+    // then
+    expect(result.removedWorktrees.sort()).toEqual([leadWorktreePath, ...fixture.worktreePaths].sort())
+    await access(leadWorktreePath).then(
+      () => { throw new Error(`expected ${leadWorktreePath} to be removed`) },
+      () => undefined,
+    )
+  })
+
+  test("force continues cleanup when removeTeamLayout throws", async () => {
+    // given
+    const fixture = await createFixture()
+    temporaryDirectories.push(fixture.baseDir)
+    const transitionedStatuses: string[] = []
+    const originalTransitionRuntimeState = runtimeStateStore.transitionRuntimeState
+    spyOn(runtimeStateStore, "transitionRuntimeState").mockImplementation(async (teamRunId, transition, config) => {
+      const currentRuntimeState = await runtimeStateStore.loadRuntimeState(teamRunId, config)
+      transitionedStatuses.push(transition(currentRuntimeState).status)
+      return await originalTransitionRuntimeState(teamRunId, transition, config)
+    })
+    spyOn(layoutModule, "canVisualize").mockReturnValue(true)
+    spyOn(layoutModule, "removeTeamLayout").mockRejectedValue(new Error("layout failed"))
+    const logSpy = spyOn(logger, "log").mockImplementation(() => {})
+    await updateMemberStatuses(fixture.teamRunId, fixture.config, {
+      "member-a": "running",
+      "member-b": "idle",
+    })
+    await Promise.all(fixture.worktreePaths.map(async (worktreePath) => {
+      await mkdir(worktreePath, { recursive: true })
+    }))
+
+    // when
+    const result = await deleteTeam(
+      fixture.teamRunId,
+      fixture.config,
+      { getServerUrl: () => "http://localhost" } as never,
+      undefined,
+      { force: true },
+    )
+
+    // then
+    expect(result.removedLayout).toBe(true)
+    expect(transitionedStatuses).toContain("deleted")
+    expect(logSpy).toHaveBeenCalledWith("team delete layout cleanup failed", {
+      teamRunId: fixture.teamRunId,
+      error: "layout failed",
+    })
+    const runtimeStateDirectory = getRuntimeStateDir(resolveBaseDir(fixture.config), fixture.teamRunId)
+    await access(runtimeStateDirectory).then(
+      () => { throw new Error(`expected ${runtimeStateDirectory} to be removed`) },
+      () => undefined,
+    )
+  })
+
+  test("cancels team background tasks before deleting when force=true", async () => {
+    // given
+    const fixture = await createFixture()
+    temporaryDirectories.push(fixture.baseDir)
+    await updateMemberStatuses(fixture.teamRunId, fixture.config, {
+      "member-a": "running",
+      "member-b": "idle",
+    })
+    const runtimeStatusesDuringCancellation: Array<{ teamStatus: string; memberStatuses: string[] }> = []
+    const cancelTaskMock = mock(async () => {
+      const runtimeState = await loadRuntimeState(fixture.teamRunId, fixture.config)
+      runtimeStatusesDuringCancellation.push({
+        teamStatus: runtimeState.status,
+        memberStatuses: runtimeState.members
+          .filter((member) => member.agentType !== "leader")
+          .map((member) => member.status),
+      })
+      return true
+    })
+    const bgMgr = {
+      getTasksByParentSession: () => [
+        { id: "team-task-a", sessionID: "session-a", parentMessageID: `team-create:${fixture.teamRunId}:member-a` },
+        { id: "team-task-b", sessionID: "session-b", parentMessageID: `team-create:${fixture.teamRunId}:member-b` },
+      ],
+      cancelTask: cancelTaskMock,
+    }
+
+    // when
+    await deleteTeam(fixture.teamRunId, fixture.config, undefined, bgMgr as never, { force: true })
+
+    // then
+    expect(cancelTaskMock).toHaveBeenCalledTimes(2)
+    expect(runtimeStatusesDuringCancellation).toEqual([
+      { teamStatus: "active", memberStatuses: ["running", "idle"] },
+      { teamStatus: "active", memberStatuses: ["running", "idle"] },
+    ])
+  })
+
+  test("blocks mailbox writes while the team is deleting", async () => {
+    // given
+    const fixture = await createFixture()
+    temporaryDirectories.push(fixture.baseDir)
+    await updateMemberStatuses(fixture.teamRunId, fixture.config, {
+      "member-a": "shutdown_approved",
+      "member-b": "shutdown_approved",
+    })
+    await transitionRuntimeState(fixture.teamRunId, (runtimeState) => ({
+      ...runtimeState,
+      status: "deleting",
+    }), fixture.config)
+
+    // when
+    const result = sendMessage(
+      createTestMessage(),
+      fixture.teamRunId,
+      fixture.config,
+      { isLead: true, activeMembers: ["lead", "member-a", "member-b"] },
+    )
+
+    // then
+    await result.then(
+      () => { throw new Error("expected sendMessage to reject") },
+      (error: unknown) => {
+        if (!(error instanceof Error)) throw error
+        expect(error.message).toBe("team is deleting")
+      },
+    )
+  })
+})
diff --git a/src/features/team-mode/team-runtime/shutdown.ts b/src/features/team-mode/team-runtime/shutdown.ts
new file mode 100644
index 000000000..920dd04ba
--- /dev/null
+++ b/src/features/team-mode/team-runtime/shutdown.ts
@@ -0,0 +1,146 @@
+import type { TeamModeConfig } from "../../../config/schema/team-mode"
+import { sendMessage } from "../team-mailbox/send"
+import { loadRuntimeState, transitionRuntimeState } from "../team-state-store/store"
+import {
+  createSendContext,
+  createShutdownMessage,
+  findLatestShutdownRequestIndex,
+  getLeadMemberName,
+  getRuntimeMember,
+} from "./shutdown-helpers"
+export { deleteTeam } from "./delete-team"
+
+export async function requestShutdownOfMember(
+  teamRunId: string,
+  targetMemberName: string,
+  requesterName: string,
+  config: TeamModeConfig,
+): Promise<void> {
+  const runtimeState = await loadRuntimeState(teamRunId, config)
+  getRuntimeMember(runtimeState, targetMemberName)
+  getRuntimeMember(runtimeState, requesterName)
+
+  const existingRequestIndex = findLatestShutdownRequestIndex(runtimeState, targetMemberName, requesterName)
+  const existingRequest = existingRequestIndex >= 0
+    ? runtimeState.shutdownRequests[existingRequestIndex]
+    : undefined
+  if (existingRequest && existingRequest.approvedAt === undefined && existingRequest.rejectedAt === undefined) {
+    return
+  }
+
+  await sendMessage(
+    createShutdownMessage(requesterName, targetMemberName, "shutdown_request", ""),
+    teamRunId,
+    config,
+    createSendContext(runtimeState, requesterName),
+  )
+
+  await transitionRuntimeState(teamRunId, (currentRuntimeState) => {
+    const duplicateRequestIndex = findLatestShutdownRequestIndex(currentRuntimeState, targetMemberName, requesterName)
+    const duplicateRequest = duplicateRequestIndex >= 0
+      ? currentRuntimeState.shutdownRequests[duplicateRequestIndex]
+      : undefined
+    if (duplicateRequest && duplicateRequest.approvedAt === undefined && duplicateRequest.rejectedAt === undefined) {
+      return currentRuntimeState
+    }
+
+    return {
+      ...currentRuntimeState,
+      shutdownRequests: [
+        ...currentRuntimeState.shutdownRequests,
+        { memberId: targetMemberName, requesterName, requestedAt: Date.now() },
+      ],
+    }
+  }, config)
+}
+
+export async function approveShutdown(
+  teamRunId: string,
+  memberName: string,
+  approverName: string,
+  config: TeamModeConfig,
+): Promise<void> {
+  const runtimeState = await loadRuntimeState(teamRunId, config)
+  getRuntimeMember(runtimeState, approverName)
+  const shutdownRequestIndex = findLatestShutdownRequestIndex(runtimeState, memberName)
+  if (shutdownRequestIndex < 0) {
+    throw new Error(`shutdown request missing for '${memberName}'`)
+  }
+
+  const existingRequest = runtimeState.shutdownRequests[shutdownRequestIndex]
+  if (existingRequest?.approvedAt !== undefined) {
+    return
+  }
+
+  const updatedRuntimeState = await transitionRuntimeState(teamRunId, (currentRuntimeState) => {
+    const currentRequestIndex = findLatestShutdownRequestIndex(currentRuntimeState, memberName)
+    if (currentRequestIndex < 0) {
+      throw new Error(`shutdown request missing for '${memberName}'`)
+    }
+
+    const currentRequest = currentRuntimeState.shutdownRequests[currentRequestIndex]
+    if (!currentRequest || currentRequest.approvedAt !== undefined) {
+      return currentRuntimeState
+    }
+
+    return {
+      ...currentRuntimeState,
+      members: currentRuntimeState.members.map((member) => {
+        if (member.name !== memberName || member.status === "completed" || member.status === "errored") {
+          return member
+        }
+
+        return { ...member, status: "shutdown_approved" }
+      }),
+      shutdownRequests: currentRuntimeState.shutdownRequests.map((shutdownRequest, index) => index === currentRequestIndex
+        ? { ...shutdownRequest, approvedAt: Date.now() }
+        : shutdownRequest),
+    }
+  }, config)
+
+  await sendMessage(
+    createShutdownMessage(approverName, getLeadMemberName(updatedRuntimeState), "shutdown_approved", memberName),
+    teamRunId,
+    config,
+    createSendContext(updatedRuntimeState, approverName),
+  )
+}
+
+export async function rejectShutdown(
+  teamRunId: string,
+  memberName: string,
+  reason: string,
+  config: TeamModeConfig,
+): Promise<void> {
+  const runtimeState = await loadRuntimeState(teamRunId, config)
+  const shutdownRequestIndex = findLatestShutdownRequestIndex(runtimeState, memberName)
+  if (shutdownRequestIndex < 0) {
+    throw new Error(`shutdown request missing for '${memberName}'`)
+  }
+
+  const shutdownRequest = runtimeState.shutdownRequests[shutdownRequestIndex]
+  if (shutdownRequest.rejectedAt !== undefined && shutdownRequest.rejectedReason === reason) {
+    return
+  }
+
+  await sendMessage(
+    createShutdownMessage(memberName, shutdownRequest.requesterName, "shutdown_rejected", reason),
+    teamRunId,
+    config,
+    createSendContext(runtimeState, memberName),
+  )
+
+  await transitionRuntimeState(teamRunId, (currentRuntimeState) => {
+    const currentRequestIndex = findLatestShutdownRequestIndex(currentRuntimeState, memberName)
+    if (currentRequestIndex < 0) {
+      throw new Error(`shutdown request missing for '${memberName}'`)
+    }
+
+    return {
+      ...currentRuntimeState,
+      shutdownRequests: currentRuntimeState.shutdownRequests.map((currentRequest, index) => index === currentRequestIndex
+        ? { ...currentRequest, rejectedAt: Date.now(), rejectedReason: reason }
+        : currentRequest),
+    }
+  }, config)
+}