diff --git a/packages/server/src/server/agent/providers/codex-app-server-agent.ts b/packages/server/src/server/agent/providers/codex-app-server-agent.ts
index 2aecd18e21..cc667b2494 100644
--- a/packages/server/src/server/agent/providers/codex-app-server-agent.ts
+++ b/packages/server/src/server/agent/providers/codex-app-server-agent.ts
@@ -150,6 +150,15 @@ function isCodexAlreadyUnarchivedError(error: unknown, threadId: string): boolea
 
 const TURN_START_TIMEOUT_MS = 90 * 1000;
 const INTERRUPT_TIMEOUT_MS = 2_000;
+// `turn/interrupt` ends a turn but leaves the shell commands it started running.
+// Each terminate is bounded by the first constant. A turn start waits for the
+// interrupted turn's commands to end, at most the interrupt's own bound plus one
+// terminate's and a margin, so it gives up only when a request outlives its timeout.
+const INTERRUPTED_TURN_TERMINATE_TIMEOUT_MS = 2_000;
+const INTERRUPTED_TURN_CLEANUP_WAIT_MS =
+  INTERRUPT_TIMEOUT_MS + INTERRUPTED_TURN_TERMINATE_TIMEOUT_MS + 500;
+// Turns whose commands are remembered; older turns are forgotten first.
+const INTERRUPTED_TURN_TRACKED_TURNS = 16;
 const CODEX_PROVIDER = "codex" as const;
 // These native provider identities belong to Codex, not to an older custom
 // Paseo provider. Never include them in a custom provider's legacy import scan.
@@ -3476,6 +3485,14 @@ export class CodexAppServerAgentSession implements AgentSession {
   private pendingFileChangeOutputDeltas = new Map<string, string[]>();
   private pendingAssistantMessageBoundary = false;
   private terminalCommandByProcessId = new Map<string, string>();
+  // The root thread's still-running command process ids, keyed by the native turn that
+  // started them. Codex's `thread/backgroundTerminals/list` carries no turn, so
+  // `item/started` is the only record of which turn owns a process.
+  private terminalProcessIdsByTurnId = new Map<
+    string,
+    { processIds: Set<string>; terminatedProcessIds: Set<string>; interruptAccepted: boolean }
+  >();
+  private interruptedTurnCleanup: Promise<void> | null = null;
   private pendingUnlabeledTerminalInteractions = new Map<
     string,
     Array<{ callId: string; stdin: string | null }>
@@ -4431,6 +4448,9 @@ export class CodexAppServerAgentSession implements AgentSession {
         hasDeveloperInstructions: turnStart.hasDeveloperInstructions,
         hasCodexConfig: turnStart.hasCodexConfig,
       });
+      // The interrupted turn's commands end before this turn begins, so none of them
+      // outlives it into the new turn.
+      await this.waitForInterruptedTurnCleanup();
       if (pendingStart.cancelRequested) {
         throw new Error("Codex turn start was interrupted before reaching Codex");
       }
@@ -5036,15 +5056,27 @@ export class CodexAppServerAgentSession implements AgentSession {
     if (!turnId || (foregroundTurnId && this.activeForegroundTurnId !== foregroundTurnId)) {
       throw new Error("Cannot interrupt Codex before turn/started identifies the active turn");
     }
+    const client = this.client;
+    const threadId = this.currentThreadId;
+    const interruptRequest = client.request(
+      "turn/interrupt",
+      {
+        threadId,
+        turnId,
+      },
+      INTERRUPT_TIMEOUT_MS,
+    );
+    // Once Codex accepts the interrupt, end the commands this turn started. Registered
+    // before the await, so a turn start racing this interrupt waits for it. An already-idle
+    // turn was not interrupted, and what it left running stays.
+    this.trackInterruptedTurnCleanup(
+      interruptRequest.then(
+        () => this.endInterruptedTurnProcesses(client, threadId, turnId),
+        () => undefined,
+      ),
+    );
     try {
-      await this.client.request(
-        "turn/interrupt",
-        {
-          threadId: this.currentThreadId,
-          turnId,
-        },
-        INTERRUPT_TIMEOUT_MS,
-      );
+      await interruptRequest;
     } catch (error) {
       if (!isCodexAlreadyIdleInterrupt(error)) {
         throw error;
@@ -5085,6 +5117,137 @@ export class CodexAppServerAgentSession implements AgentSession {
     return !this.client.hasPendingRequests();
   }
 
+  // Remember which turn started a command, so an interrupt ends that turn's commands and
+  // no other turn's. Only the root thread's: a subagent's commands live on its own thread.
+  // A command that starts after its turn's interrupt was accepted is ended as soon as it
+  // is seen.
+  private recordTurnTerminalProcess(
+    parsed: Extract<ParsedCodexNotification, { kind: "item_started" | "item_completed" }>,
+  ): void {
+    const processId = parsed.item.processId;
+    if (
+      parsed.source !== "item" ||
+      !parsed.turnId ||
+      !parsed.threadId ||
+      parsed.threadId !== this.currentThreadId ||
+      typeof processId !== "string" ||
+      !processId ||
+      normalizeCodexThreadItemType(
+        typeof parsed.item.type === "string" ? parsed.item.type : undefined,
+      ) !== "commandExecution"
+    ) {
+      return;
+    }
+    const record = this.terminalProcessIdsByTurnId.get(parsed.turnId);
+    if (parsed.kind === "item_completed") {
+      // Only a completed command has exited. A failed one can still be running:
+      // Codex reports an interrupted turn's live command as failed.
+      if (parsed.item.status === "completed") record?.processIds.delete(processId);
+      return;
+    }
+    const current = record ?? this.getTurnTerminalRecord(parsed.turnId);
+    current.processIds.add(processId);
+    if (current.interruptAccepted && this.client) {
+      this.trackInterruptedTurnCleanup(
+        this.endInterruptedTurnProcesses(this.client, parsed.threadId, parsed.turnId),
+      );
+    }
+  }
+
+  // An accepted interrupt needs a record even before any of its turn's commands is seen:
+  // an `item/started` can still be queued behind an earlier notification's conversion.
+  private getTurnTerminalRecord(turnId: string) {
+    const existing = this.terminalProcessIdsByTurnId.get(turnId);
+    if (existing) return existing;
+    const record = {
+      processIds: new Set<string>(),
+      terminatedProcessIds: new Set<string>(),
+      interruptAccepted: false,
+    };
+    this.terminalProcessIdsByTurnId.set(turnId, record);
+    for (const oldestTurnId of this.terminalProcessIdsByTurnId.keys()) {
+      if (this.terminalProcessIdsByTurnId.size <= INTERRUPTED_TURN_TRACKED_TURNS) break;
+      this.terminalProcessIdsByTurnId.delete(oldestTurnId);
+    }
+    return record;
+  }
+
+  // A later sweep joins the pending one, so a turn start waits for both.
+  private trackInterruptedTurnCleanup(cleanup: Promise<void>): void {
+    const tracked = Promise.all([this.interruptedTurnCleanup, cleanup])
+      .then(() => undefined)
+      .finally(() => {
+        if (this.interruptedTurnCleanup === tracked) this.interruptedTurnCleanup = null;
+      });
+    this.interruptedTurnCleanup = tracked;
+  }
+
+  // Terminate each process the interrupted turn started, by its own id, once each.
+  // `thread/backgroundTerminals/clean` is never used: it ends every terminal on the thread,
+  // an earlier turn's included. A process already gone answers `terminated: false`. Never
+  // rejects; failures are logged.
+  private async endInterruptedTurnProcesses(
+    client: CodexAppServerClient,
+    threadId: string | null,
+    turnId: string,
+  ): Promise<void> {
+    if (!threadId) return;
+    const record = this.getTurnTerminalRecord(turnId);
+    record.interruptAccepted = true;
+    const processIds = [...record.processIds].filter(
+      (processId) => !record.terminatedProcessIds.has(processId),
+    );
+    for (const processId of processIds) record.terminatedProcessIds.add(processId);
+    const logContext = { agentId: this.agentId, provider: CODEX_PROVIDER, threadId, turnId };
+    await Promise.all(
+      processIds.map(async (processId) => {
+        try {
+          const response = await client.request(
+            "thread/backgroundTerminals/terminate",
+            { threadId, processId },
+            INTERRUPTED_TURN_TERMINATE_TIMEOUT_MS,
+          );
+          this.logger.info(
+            { ...logContext, processId, terminated: toObjectRecord(response)?.terminated ?? null },
+            "provider.codex.interrupt.terminal_terminated",
+          );
+        } catch (error) {
+          this.logger.warn(
+            { ...logContext, processId, err: error },
+            "provider.codex.interrupt.terminal_terminate_failed",
+          );
+        }
+      }),
+    );
+  }
+
+  // A new turn starts only after every pending sweep of interrupted turns' commands has
+  // ended, or after the bound, whichever is first.
+  private async waitForInterruptedTurnCleanup(): Promise<void> {
+    if (!this.interruptedTurnCleanup) return;
+    let timer: ReturnType<typeof setTimeout> | undefined;
+    const timedOut = await Promise.race([
+      (async () => {
+        while (this.interruptedTurnCleanup) await this.interruptedTurnCleanup;
+        return false;
+      })(),
+      new Promise<boolean>((resolve) => {
+        timer = setTimeout(() => resolve(true), INTERRUPTED_TURN_CLEANUP_WAIT_MS);
+      }),
+    ]);
+    clearTimeout(timer);
+    if (timedOut) {
+      this.logger.warn(
+        {
+          agentId: this.agentId,
+          provider: CODEX_PROVIDER,
+          waitMs: INTERRUPTED_TURN_CLEANUP_WAIT_MS,
+        },
+        "provider.codex.interrupt.terminal_cleanup_timed_out",
+      );
+    }
+  }
+
   async close(): Promise<void> {
     this.closed = true;
     this.clearPendingPermissions();
@@ -6209,6 +6372,11 @@ export class CodexAppServerAgentSession implements AgentSession {
       return;
     }
     this.completePendingRootCompactions();
+    // What a turn that was not interrupted leaves running, it left on purpose; no later
+    // interrupt may end it.
+    if (parsed.status !== "interrupted" && this.currentTurnId) {
+      this.terminalProcessIdsByTurnId.delete(this.currentTurnId);
+    }
     if (parsed.status === "failed") {
       this.emitEvent({
         type: "turn_failed",
@@ -6613,6 +6781,7 @@ export class CodexAppServerAgentSession implements AgentSession {
   private async handleItemCompletedNotification(
     parsed: Extract<ParsedCodexNotification, { kind: "item_completed" }>,
   ): Promise<void> {
+    this.recordTurnTerminalProcess(parsed);
     // Codex emits mirrored lifecycle notifications via both `codex/event/item_*`
     // and canonical `item/*`. Render ordinary items only from the canonical
     // channel, but accept a legacy-only child announcement so it can establish
@@ -6775,6 +6944,7 @@ export class CodexAppServerAgentSession implements AgentSession {
   private async handleItemStartedNotification(
     parsed: Extract<ParsedCodexNotification, { kind: "item_started" }>,
   ): Promise<void> {
+    this.recordTurnTerminalProcess(parsed);
     if (shouldIgnoreMirroredLifecycleItem(parsed.source, parsed.item)) {
       return;
     }
diff --git a/packages/server/src/server/agent/providers/codex-interrupted-turn-terminals.test.ts b/packages/server/src/server/agent/providers/codex-interrupted-turn-terminals.test.ts
new file mode 100644
index 0000000000..3d2ea64f9a
--- /dev/null
+++ b/packages/server/src/server/agent/providers/codex-interrupted-turn-terminals.test.ts
@@ -0,0 +1,374 @@
+import { afterEach, describe, expect, test, vi } from "vitest";
+
+import type { AgentSession } from "../agent-sdk-types.js";
+import { createTestLogger } from "../../../test-utils/test-logger.js";
+import { CodexAppServerAgentSession } from "./codex-app-server-agent.js";
+import {
+  createFakeCodexAppServer,
+  type FakeCodexAppServer,
+  waitForNextEvent,
+  waitForTimelineToolCall,
+} from "./codex/test-utils/fake-app-server.js";
+
+const THREAD = "thread-1";
+const TERMINATE = "thread/backgroundTerminals/terminate";
+
+type Handler = (params: unknown) => unknown;
+
+function deferred<T = void>() {
+  let resolve!: (value: T) => void;
+  const promise = new Promise<T>((resolvePromise) => {
+    resolve = resolvePromise;
+  });
+  return { promise, resolve };
+}
+
+function paramsOf(value: unknown): Record<string, unknown> {
+  return value && typeof value === "object" ? (value as Record<string, unknown>) : {};
+}
+
+let sessions: AgentSession[] = [];
+
+afterEach(async () => {
+  for (const session of sessions) await session.close().catch(() => undefined);
+  sessions = [];
+});
+
+/**
+ * A Codex app-server whose interrupt ends the turn the way Codex does: an `interrupted`
+ * turn completion, then the response. `terminate` answers per process.
+ */
+function createHarness(
+  options: {
+    terminate?: (processId: string) => unknown;
+    interruptResponse?: (completeTurn: () => void) => unknown;
+  } = {},
+) {
+  const handlers: Record<string, Handler> = {
+    "turn/interrupt": () => {
+      const completeTurn = () =>
+        appServer.completeTurn({ threadId: THREAD, status: "interrupted" });
+      if (options.interruptResponse) return options.interruptResponse(completeTurn);
+      completeTurn();
+      return {};
+    },
+    [TERMINATE]: (params) =>
+      options.terminate?.(String(paramsOf(params).processId)) ?? { terminated: true },
+  };
+  const appServer: FakeCodexAppServer = createFakeCodexAppServer(handlers);
+  const session = new CodexAppServerAgentSession(
+    {
+      provider: "codex",
+      cwd: "/workspace/project",
+      modeId: "auto",
+      model: "gpt-5.4",
+    },
+    null,
+    createTestLogger(),
+    async () => appServer.child,
+  );
+  sessions.push(session);
+
+  function requests(method: string): Record<string, unknown>[] {
+    return appServer
+      .requests()
+      .filter((message) => message.method === method && "id" in message)
+      .map((message) => paramsOf(message.params));
+  }
+
+  function terminated(): string[] {
+    return requests(TERMINATE)
+      .map((params) => String(params.processId))
+      .sort();
+  }
+
+  // Starts a turn and lets Codex identify it as `nativeTurnId`.
+  async function startTurn(prompt: string, nativeTurnId: string): Promise<void> {
+    const before = requests("turn/start").length;
+    const started = session.startTurn(prompt);
+    await vi.waitFor(() => expect(requests("turn/start")).toHaveLength(before + 1), {
+      timeout: 5_000,
+    });
+    const turnStarted = waitForNextEvent(session, "turn_started");
+    appServer.startsTurn({ threadId: THREAD, turnId: nativeTurnId });
+    await started;
+    await turnStarted;
+  }
+
+  async function runsCommand(params: { turnId: string; processId: string }): Promise<void> {
+    const itemId = `exec-${params.processId}`;
+    const shown = waitForTimelineToolCall(session, itemId);
+    appServer.startsTerminalCommand({
+      threadId: THREAD,
+      turnId: params.turnId,
+      itemId,
+      processId: params.processId,
+      command: `sleep ${params.processId}`,
+    });
+    await shown;
+  }
+
+  async function completesTurn(): Promise<void> {
+    const completed = waitForNextEvent(session, "turn_completed");
+    appServer.completeTurn({ threadId: THREAD });
+    await completed;
+  }
+
+  // Interrupts the running turn and waits for the session to report it canceled, as a
+  // caller does before it starts the next turn: Codex notifications are handled in order
+  // but asynchronously, so the interrupt's answer can arrive before the turn has ended.
+  async function interrupts(): Promise<void> {
+    const canceled = waitForNextEvent(session, "turn_canceled");
+    await session.interrupt();
+    await canceled;
+  }
+
+  return {
+    appServer,
+    session,
+    requests,
+    terminated,
+    startTurn,
+    runsCommand,
+    completesTurn,
+    interrupts,
+  };
+}
+
+// Turn A leaves a server running on purpose and completes. Turn B starts two
+// commands, and a subagent on its own thread starts a third, then B is interrupted.
+async function interruptTurnB(harness: ReturnType<typeof createHarness>): Promise<void> {
+  await harness.startTurn("start a server", "native-A");
+  await harness.runsCommand({ turnId: "native-A", processId: "101" });
+  await harness.completesTurn();
+
+  await harness.startTurn("run two commands", "native-B");
+  await harness.runsCommand({ turnId: "native-B", processId: "201" });
+  // A subagent thread's command shows no row here; the next command's row shows it
+  // was read, because notifications are read in order.
+  harness.appServer.startsTerminalCommand({
+    threadId: "child-thread",
+    turnId: "native-B",
+    itemId: "exec-209",
+    processId: "209",
+    command: "sleep 209",
+  });
+  await harness.runsCommand({ turnId: "native-B", processId: "202" });
+  await harness.interrupts();
+}
+
+describe("an interrupted Codex turn's commands end before the next turn", () => {
+  test("terminates exactly the processes the interrupted turn started, by id, and never cleans", async () => {
+    const harness = createHarness();
+    await interruptTurnB(harness);
+    await harness.startTurn("correction", "native-C");
+
+    expect(harness.terminated()).toEqual(["201", "202"]);
+    expect(harness.requests(TERMINATE).every((params) => params.threadId === THREAD)).toBe(true);
+    // `clean` would end every terminal on the thread, an earlier turn's included.
+    expect(
+      harness.appServer
+        .requests()
+        .filter((message) => String(message.method).startsWith("thread/backgroundTerminals/"))
+        .map((message) => message.method),
+    ).toEqual([TERMINATE, TERMINATE]);
+    harness.appServer.assertNoErrors();
+  });
+
+  test("leaves the next turn's commands running when Codex starts that turn before acknowledging the interrupt", async () => {
+    const acknowledge = deferred();
+    const harness = createHarness({
+      // Codex ends B, starts a turn of its own (a goal continuation), and only then
+      // answers the interrupt.
+      interruptResponse: (completeTurn) => {
+        completeTurn();
+        return acknowledge.promise.then(() => ({}));
+      },
+    });
+    await harness.startTurn("run two commands", "native-B");
+    await harness.runsCommand({ turnId: "native-B", processId: "201" });
+    await harness.runsCommand({ turnId: "native-B", processId: "202" });
+    const interrupting = harness.session.interrupt();
+    await vi.waitFor(() => expect(harness.requests("turn/interrupt")).toHaveLength(1));
+    const autonomousTurn = waitForNextEvent(harness.session, "turn_started");
+    harness.appServer.startsTurn({ threadId: THREAD, turnId: "native-C" });
+    await autonomousTurn;
+    await harness.runsCommand({ turnId: "native-C", processId: "301" });
+
+    acknowledge.resolve();
+    await interrupting;
+    await vi.waitFor(() => expect(harness.terminated()).toEqual(["201", "202"]));
+    await new Promise((resolve) => setTimeout(resolve, 50));
+    expect(harness.terminated()).toEqual(["201", "202"]);
+  });
+
+  test("sends the next turn/start only after the terminates are answered", async () => {
+    const answer = deferred();
+    const harness = createHarness({
+      terminate: () => answer.promise.then(() => ({ terminated: true })),
+    });
+    await interruptTurnB(harness);
+    const next = harness.startTurn("correction", "native-C");
+    await vi.waitFor(() => expect(harness.terminated()).toEqual(["201", "202"]));
+    await new Promise((resolve) => setTimeout(resolve, 200));
+    expect(harness.requests("turn/start")).toHaveLength(2);
+
+    answer.resolve();
+    await next;
+    expect(harness.requests("turn/start")).toHaveLength(3);
+  });
+
+  test.each(["initial", "late"] as const)(
+    "tracks both cleanup sweeps when the %s answer arrives first",
+    async (answeredFirst) => {
+      const first = deferred();
+      const second = deferred();
+      const harness = createHarness({
+        terminate: (processId) =>
+          (processId === "201" ? first : second).promise.then(() => ({ terminated: true })),
+      });
+      await harness.startTurn("run commands", "native-B");
+      await harness.runsCommand({ turnId: "native-B", processId: "201" });
+      await harness.interrupts();
+      await vi.waitFor(() => expect(harness.terminated()).toEqual(["201"]));
+      const next = harness.startTurn("correction", "native-C");
+      await new Promise((resolve) => setTimeout(resolve, 100));
+      expect(harness.requests("turn/start")).toHaveLength(1);
+      // The next turn is already waiting when another process is announced.
+      harness.appServer.startsTerminalCommand({
+        threadId: THREAD,
+        turnId: "native-B",
+        itemId: "late-202",
+        processId: "202",
+        command: "sleep 202",
+      });
+      harness.appServer.startsTerminalCommand({
+        threadId: THREAD,
+        turnId: "native-B",
+        itemId: "duplicate-202",
+        processId: "202",
+        command: "sleep 202",
+      });
+      await vi.waitFor(() => expect(harness.terminated()).toEqual(["201", "202"]));
+      (answeredFirst === "initial" ? first : second).resolve();
+      await new Promise((resolve) => setTimeout(resolve, 100));
+      expect(harness.requests("turn/start")).toHaveLength(1);
+      (answeredFirst === "initial" ? second : first).resolve();
+      await next;
+      expect(harness.terminated()).toEqual(["201", "202"]);
+      // Accepted state survives the completed sweep and a newer foreground turn.
+      harness.appServer.startsTerminalCommand({
+        threadId: THREAD,
+        turnId: "native-B",
+        itemId: "late-203",
+        processId: "203",
+        command: "sleep 203",
+      });
+      await vi.waitFor(() => expect(harness.terminated()).toEqual(["201", "202", "203"]));
+      harness.appServer.assertNoErrors();
+    },
+  );
+
+  test("keeps the first sweep pending when a late sweep answers before the next start", async () => {
+    const first = deferred();
+    const harness = createHarness({
+      terminate: (processId) =>
+        processId === "201"
+          ? first.promise.then(() => ({ terminated: true }))
+          : { terminated: true },
+    });
+    await harness.startTurn("run commands", "native-B");
+    await harness.runsCommand({ turnId: "native-B", processId: "201" });
+    await harness.interrupts();
+    harness.appServer.startsTerminalCommand({
+      threadId: THREAD,
+      turnId: "native-B",
+      itemId: "late-202",
+      processId: "202",
+      command: "sleep 202",
+    });
+    await vi.waitFor(() => expect(harness.terminated()).toEqual(["201", "202"]));
+    const next = harness.startTurn("correction", "native-C");
+    await new Promise((resolve) => setTimeout(resolve, 100));
+    expect(harness.requests("turn/start")).toHaveLength(1);
+    first.resolve();
+    await next;
+    harness.appServer.assertNoErrors();
+  });
+
+  test("forgets completed commands but retains failed commands at interrupt", async () => {
+    const harness = createHarness();
+    await harness.startTurn("run commands", "native-B");
+    for (const processId of ["201", "202"]) {
+      await harness.runsCommand({ turnId: "native-B", processId });
+      harness.appServer.child.stdout.write(
+        JSON.stringify({
+          method: "item/completed",
+          params: {
+            threadId: THREAD,
+            turnId: "native-B",
+            item: {
+              id: `exec-${processId}`,
+              type: "commandExecution",
+              processId,
+              command: `sleep ${processId}`,
+              status: processId === "201" ? "completed" : "failed",
+              exitCode: processId === "201" ? 0 : null,
+            },
+          },
+        }) + "\n",
+      );
+    }
+    // A following command's row is a barrier for both completion handlers.
+    await harness.runsCommand({ turnId: "native-B", processId: "203" });
+    await harness.interrupts();
+    await harness.startTurn("correction", "native-C");
+    expect(harness.terminated()).toEqual(["202", "203"]);
+    harness.appServer.assertNoErrors();
+  });
+
+  test("retains accepted interrupts for only the latest sixteen turns", async () => {
+    const harness = createHarness();
+    for (let index = 0; index < 17; index++) {
+      await harness.startTurn("run a command", `native-${index}`);
+      await harness.interrupts();
+    }
+    await harness.startTurn("correction", "native-current");
+    harness.appServer.startsTerminalCommand({
+      threadId: THREAD,
+      turnId: "native-0",
+      itemId: "evicted-201",
+      processId: "201",
+      command: "sleep 201",
+    });
+    harness.appServer.startsTerminalCommand({
+      threadId: THREAD,
+      turnId: "native-16",
+      itemId: "retained-202",
+      processId: "202",
+      command: "sleep 202",
+    });
+    await harness.runsCommand({ turnId: "native-current", processId: "301" });
+    expect(harness.terminated()).toEqual(["202"]);
+    harness.appServer.assertNoErrors();
+  });
+
+  test("a failing or unanswered terminate does not block or fail the next turn", async () => {
+    const harness = createHarness({
+      // 201 is refused while the next turn waits; 202 is never answered.
+      terminate: (processId) =>
+        processId === "201"
+          ? new Promise((resolve) => setTimeout(resolve, 300)).then(() => ({
+              __jsonRpcError: { code: -32600, message: "invalid background terminal process id" },
+            }))
+          : new Promise(() => {}),
+    });
+    await interruptTurnB(harness);
+    const startedAt = Date.now();
+    await harness.startTurn("correction", "native-C");
+
+    expect(Date.now() - startedAt).toBeLessThan(5_000);
+    expect(harness.requests("turn/start")).toHaveLength(3);
+    expect(harness.terminated()).toEqual(["201", "202"]);
+  }, 15_000);
+});