diff --git a/client/src/components/cos/tabs/RelaunchAgentModal.jsx b/client/src/components/cos/tabs/RelaunchAgentModal.jsx
index 842834b40b..44820877bd 100644
--- a/client/src/components/cos/tabs/RelaunchAgentModal.jsx
+++ b/client/src/components/cos/tabs/RelaunchAgentModal.jsx
@@ -6,6 +6,7 @@ import Modal from '../../ui/Modal';
 import AppContextPicker from '../../AppContextPicker';
 import ProviderModelSelector from '../../ProviderModelSelector';
 import { FormField } from '../../ui/FormField';
+import CollapsibleText from '../../ui/CollapsibleText';
 import { useAsyncAction } from '../../../hooks/useAsyncAction';
 import { effortAwareModelOptions, seedModelEffort } from '../../../utils/providers';
 
@@ -104,7 +105,20 @@ export default function RelaunchAgentModal({ agent, providers, apps, onDone, onC
 
       <div className="mb-4 p-3 bg-port-bg border border-port-border rounded-lg">
         <div className="text-sm text-gray-400 mb-1">Current task</div>
-        <div className="text-white">{taskDescription}</div>
+        {/* A task description is the agent's whole prompt — routinely hundreds of
+            lines. Rendered in full it pushes the provider/model selects and the
+            Relaunch button off a phone screen, so it opens clamped. Expanding
+            swaps in a height-capped scroll box rather than unclamping in place:
+            the point of the dialog is the controls below it, and an expanded
+            prompt must not bury them again. */}
+        <CollapsibleText
+          id={`relaunch-task-${agent?.id || 'current'}`}
+          text={taskDescription}
+          lines={3}
+          className="text-white"
+          expandedContent={taskDescription}
+          expandedClassName="max-h-48 overflow-y-auto whitespace-pre-wrap"
+        />
         <div className="text-sm text-gray-400 mt-2">
           This stops the running agent and requeues the same task on the worktree it leaves
           behind — no second agent, and nothing to clean up afterward.
diff --git a/client/src/components/cos/tabs/RelaunchAgentModal.test.jsx b/client/src/components/cos/tabs/RelaunchAgentModal.test.jsx
index 67c6466100..1c3c314acf 100644
--- a/client/src/components/cos/tabs/RelaunchAgentModal.test.jsx
+++ b/client/src/components/cos/tabs/RelaunchAgentModal.test.jsx
@@ -1,4 +1,4 @@
-import { beforeEach, describe, expect, it, vi } from 'vitest';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
 import { render, screen, waitFor } from '@testing-library/react';
 import userEvent from '@testing-library/user-event';
 
@@ -43,6 +43,12 @@ beforeEach(() => {
   api.relaunchCosAgent.mockResolvedValue({ success: true, taskId: 'task-abc', mode: 'requeued' });
 });
 
+// A prototype getter spy would otherwise survive a failing assertion and leak
+// into every test that runs after it.
+afterEach(() => {
+  vi.restoreAllMocks();
+});
+
 describe('RelaunchAgentModal', () => {
   it('submits the stalled run\'s own settings when the user changes nothing', async () => {
     const user = userEvent.setup();
@@ -92,6 +98,31 @@ describe('RelaunchAgentModal', () => {
     expect(toast.success).not.toHaveBeenCalledWith(expect.stringMatching(/queued again/i));
   });
 
+  // A task description is the agent's whole prompt. Rendered in full it pushes
+  // the provider/model selects and the Relaunch button off a phone screen, so
+  // the dialog must open on a clamped preview and cap the expanded body's height.
+  it('opens the task prompt collapsed and caps it in a scroll box when expanded', async () => {
+    // jsdom reports 0 for scrollHeight and clientHeight alike, so nothing ever
+    // measures as overflowing without this.
+    vi.spyOn(HTMLElement.prototype, 'scrollHeight', 'get').mockReturnValue(500);
+    const user = userEvent.setup();
+    const prompt = Array.from({ length: 200 }, (_, i) => `step ${i}`).join('\n');
+    renderModal({ agent: { ...STALLED_AGENT, metadata: { ...STALLED_AGENT.metadata, taskDescription: prompt } } });
+
+    const preview = document.getElementById('relaunch-task-agent-live');
+    expect(preview.className).toContain('line-clamp-3');
+
+    await user.click(screen.getByRole('button', { name: /show more/i }));
+
+    const expanded = document.getElementById('relaunch-task-agent-live');
+    expect(expanded.className).not.toContain('line-clamp-3');
+    expect(expanded.className).toContain('max-h-48');
+    expect(expanded.className).toContain('overflow-y-auto');
+    // The way back matters most on a phone — expanding must not strand the user
+    // in the prompt with the form below it out of reach.
+    expect(screen.getByRole('button', { name: /show less/i })).toBeInTheDocument();
+  });
+
   it('keeps the dialog open and surfaces the error when the relaunch fails', async () => {
     const user = userEvent.setup();
     const onClose = vi.fn();