diff --git a/packages/paperclip-runner/src/live/runnerd-codex-transport.test.ts b/packages/paperclip-runner/src/live/runnerd-codex-transport.test.ts
index debd0c6e3f..99c26734f8 100644
--- a/packages/paperclip-runner/src/live/runnerd-codex-transport.test.ts
+++ b/packages/paperclip-runner/src/live/runnerd-codex-transport.test.ts
@@ -2158,6 +2158,32 @@ it.each(["installed", "explicit"] as const)("records the selected %s Codex comma
   }
 });
 
+it.each([false, true])("binds detached-process guidance only for a trusted persistent computer (%s)", async (computer) => {
+  const root = await mkdtemp(join(tmpdir(), "paperclip-computer-process-guidance-"));
+  const runnerBinary = join(root, "runnerd");
+  await writeFile(runnerBinary, "unexecuted fixture artifact", { mode: 0o700 });
+  let instructions = "";
+  const { transport } = createCapabilityRunnerdCodexTransport({
+    provider: "codex", runnerBinary, stateDirectory: root, sourceCodexHome: "",
+    codexCommand: "/qualified/codex", persistentAgentHome: computer ? "/agent/home" : undefined,
+    controlPlaneRegistration: async (authority) => {
+      instructions = String((authority.store.state.runAttachTemplate!.provider as { instructions: string }).instructions);
+      throw new Error("fixture_stop_before_runner_launch");
+    },
+    runnerProcessLauncher: () => { throw new Error("must not launch"); },
+  });
+  try {
+    await expect(transport.request("thread/start", { cwd: root, model: "gpt-6.1-sol", dynamicTools: [],
+      developerInstructions: "Preserve the task instructions." })).rejects.toThrow("fixture_stop_before_runner_launch");
+    expect(instructions).toContain("Preserve the task instructions.");
+    expect(instructions.includes("nohup setsid")).toBe(computer);
+    if (computer) {
+      expect(instructions).toContain("stop when its warm timeout expires");
+      expect(instructions).toContain("Do not create services or change runner ownership");
+    }
+  } finally { await transport.close(); await rm(root, { recursive: true, force: true }); }
+});
+
 it("rejects remote Codex without a guest executable before resolving controller dependencies", async () => {
   const root = await mkdtemp(join(tmpdir(), "paperclip-runner-remote-codex-command-"));
   const runnerBinary = join(root, "runnerd");