diff --git a/apps/youaskm3/web-react/src/App.test.tsx b/apps/youaskm3/web-react/src/App.test.tsx
index aff8c84..fb8f759 100644
--- a/apps/youaskm3/web-react/src/App.test.tsx
+++ b/apps/youaskm3/web-react/src/App.test.tsx
@@ -7,8 +7,8 @@ describe('App', () => {
     expect(screen.getByRole('heading', { name: /youaskm3/i })).toBeInTheDocument()
   })
 
-  it('shows the default runtime URL', () => {
+  it('renders the run button', () => {
     render(<App />)
-    expect(screen.getByText(/localhost:3000/)).toBeInTheDocument()
+    expect(screen.getByRole('button', { name: /run/i })).toBeInTheDocument()
   })
 })
diff --git a/apps/youaskm3/web-react/src/App.tsx b/apps/youaskm3/web-react/src/App.tsx
index deb197b..627fc57 100644
--- a/apps/youaskm3/web-react/src/App.tsx
+++ b/apps/youaskm3/web-react/src/App.tsx
@@ -1,10 +1,36 @@
+import { useMemo } from 'react'
+import { createTraverseClient } from './client/traverseClient'
+import { useExecution } from './hooks/useExecution'
+
+const BASE_URL = import.meta.env.VITE_TRAVERSE_BASE_URL ?? 'http://127.0.0.1:8787'
+const WORKSPACE = import.meta.env.VITE_TRAVERSE_WORKSPACE ?? 'local-default'
+
 function App() {
-  const runtimeUrl = import.meta.env.VITE_TRAVERSE_RUNTIME_URL || 'http://localhost:3000'
+  const client = useMemo(() => createTraverseClient(BASE_URL), [])
+  const { state, run } = useExecution(client, WORKSPACE)
+
+  const handleRun = () => {
+    run('youaskm3.answer', { question: 'What is Traverse?' })
+  }
 
   return (
     <main>
       <h1>youaskm3</h1>
-      <p>Runtime: {runtimeUrl}</p>
+      <p>Runtime: {BASE_URL} · Workspace: {WORKSPACE}</p>
+
+      <button onClick={handleRun} disabled={state.phase === 'loading' || state.phase === 'polling'}>
+        Run
+      </button>
+
+      {state.phase === 'loading' && <p>Starting…</p>}
+      {state.phase === 'polling' && <p>Polling {state.executionId}…</p>}
+      {state.phase === 'succeeded' && (
+        <div>
+          <p>Done: {JSON.stringify(state.result.output)}</p>
+          {state.trace.length > 0 && <p>Trace events: {state.trace.length}</p>}
+        </div>
+      )}
+      {state.phase === 'failed' && <p>Error: {state.error}</p>}
     </main>
   )
 }
diff --git a/apps/youaskm3/web-react/src/client/traverseClient.test.ts b/apps/youaskm3/web-react/src/client/traverseClient.test.ts
new file mode 100644
index 0000000..82358eb
--- /dev/null
+++ b/apps/youaskm3/web-react/src/client/traverseClient.test.ts
@@ -0,0 +1,52 @@
+import { createTraverseClient } from './traverseClient'
+
+const BASE = 'http://localhost:8787'
+
+function mockFetch(responses: Record<string, unknown>) {
+  return vi.fn((url: string) => {
+    const key = Object.keys(responses).find(k => url.includes(k))
+    if (!key) return Promise.resolve({ ok: false, status: 404 })
+    return Promise.resolve({
+      ok: true,
+      json: () => Promise.resolve(responses[key]),
+    })
+  }) as unknown as typeof fetch
+}
+
+describe('createTraverseClient', () => {
+  it('execute posts and returns execution_id', async () => {
+    const fetch = mockFetch({ '/execute': { execution_id: 'exec-1' } })
+    global.fetch = fetch
+    const client = createTraverseClient(BASE)
+    const id = await client.execute('local-default', 'cap.foo', { q: 'hi' })
+    expect(id).toBe('exec-1')
+    expect(fetch).toHaveBeenCalledWith(
+      `${BASE}/v1/workspaces/local-default/execute`,
+      expect.objectContaining({ method: 'POST' }),
+    )
+  })
+
+  it('pollExecution returns result', async () => {
+    const fetch = mockFetch({ '/executions/exec-1': { execution_id: 'exec-1', status: 'succeeded', output: 42 } })
+    global.fetch = fetch
+    const client = createTraverseClient(BASE)
+    const result = await client.pollExecution('local-default', 'exec-1')
+    expect(result.status).toBe('succeeded')
+    expect(result.output).toBe(42)
+  })
+
+  it('fetchTrace returns events', async () => {
+    const fetch = mockFetch({ '/traces/exec-1': [{ event_type: 'start', timestamp: 't0' }] })
+    global.fetch = fetch
+    const client = createTraverseClient(BASE)
+    const trace = await client.fetchTrace('local-default', 'exec-1')
+    expect(trace).toHaveLength(1)
+    expect(trace[0].event_type).toBe('start')
+  })
+
+  it('execute throws on non-ok response', async () => {
+    global.fetch = vi.fn(() => Promise.resolve({ ok: false, status: 500 })) as unknown as typeof fetch
+    const client = createTraverseClient(BASE)
+    await expect(client.execute('ws', 'cap', {})).rejects.toThrow('execute failed: 500')
+  })
+})
diff --git a/apps/youaskm3/web-react/src/client/traverseClient.ts b/apps/youaskm3/web-react/src/client/traverseClient.ts
new file mode 100644
index 0000000..dc538f3
--- /dev/null
+++ b/apps/youaskm3/web-react/src/client/traverseClient.ts
@@ -0,0 +1,54 @@
+export type ExecutionStatus = 'pending' | 'running' | 'succeeded' | 'failed'
+
+export interface ExecutionResult {
+  execution_id: string
+  status: ExecutionStatus
+  output?: unknown
+  error?: string
+}
+
+export interface TraceEvent {
+  event_type: string
+  timestamp: string
+  data?: unknown
+}
+
+export interface TraverseClient {
+  execute(workspaceId: string, capability: string, input: unknown): Promise<string>
+  pollExecution(workspaceId: string, executionId: string): Promise<ExecutionResult>
+  fetchTrace(workspaceId: string, executionId: string): Promise<TraceEvent[]>
+}
+
+export function createTraverseClient(baseUrl: string): TraverseClient {
+  return {
+    async execute(workspaceId, capability, input) {
+      const res = await fetch(
+        `${baseUrl}/v1/workspaces/${workspaceId}/execute`,
+        {
+          method: 'POST',
+          headers: { 'Content-Type': 'application/json' },
+          body: JSON.stringify({ capability, input }),
+        },
+      )
+      if (!res.ok) throw new Error(`execute failed: ${res.status}`)
+      const data = (await res.json()) as { execution_id: string }
+      return data.execution_id
+    },
+
+    async pollExecution(workspaceId, executionId) {
+      const res = await fetch(
+        `${baseUrl}/v1/workspaces/${workspaceId}/executions/${executionId}`,
+      )
+      if (!res.ok) throw new Error(`poll failed: ${res.status}`)
+      return (await res.json()) as ExecutionResult
+    },
+
+    async fetchTrace(workspaceId, executionId) {
+      const res = await fetch(
+        `${baseUrl}/v1/workspaces/${workspaceId}/traces/${executionId}`,
+      )
+      if (!res.ok) throw new Error(`trace fetch failed: ${res.status}`)
+      return (await res.json()) as TraceEvent[]
+    },
+  }
+}
diff --git a/apps/youaskm3/web-react/src/hooks/useExecution.test.ts b/apps/youaskm3/web-react/src/hooks/useExecution.test.ts
new file mode 100644
index 0000000..e6135c1
--- /dev/null
+++ b/apps/youaskm3/web-react/src/hooks/useExecution.test.ts
@@ -0,0 +1,77 @@
+import { renderHook, act } from '@testing-library/react'
+import { useExecution } from './useExecution'
+import type { TraverseClient, ExecutionResult } from '../client/traverseClient'
+
+function makeClient(overrides: Partial<TraverseClient> = {}): TraverseClient {
+  return {
+    execute: vi.fn().mockResolvedValue('exec-1'),
+    pollExecution: vi.fn().mockResolvedValue({
+      execution_id: 'exec-1',
+      status: 'succeeded',
+      output: 'ok',
+    } as ExecutionResult),
+    fetchTrace: vi.fn().mockResolvedValue([]),
+    ...overrides,
+  }
+}
+
+const POLL_MS = 10
+
+describe('useExecution', () => {
+  beforeEach(() => vi.useFakeTimers())
+  afterEach(() => vi.useRealTimers())
+
+  it('starts idle', () => {
+    const { result } = renderHook(() => useExecution(makeClient(), 'ws', POLL_MS))
+    expect(result.current.state.phase).toBe('idle')
+  })
+
+  it('transitions loading → succeeded via polling', async () => {
+    const client = makeClient()
+    const { result } = renderHook(() => useExecution(client, 'ws', POLL_MS))
+
+    act(() => { result.current.run('cap', {}) })
+    expect(result.current.state.phase).toBe('loading')
+
+    // flush execute promise, interval not yet fired
+    await act(async () => { await Promise.resolve() })
+    expect(result.current.state.phase).toBe('polling')
+
+    // fire the poll interval
+    await act(async () => { await vi.advanceTimersByTimeAsync(POLL_MS) })
+    expect(result.current.state.phase).toBe('succeeded')
+  })
+
+  it('transitions to failed when execute throws', async () => {
+    const client = makeClient({
+      execute: vi.fn().mockRejectedValue(new Error('net error')),
+    })
+    const { result } = renderHook(() => useExecution(client, 'ws', POLL_MS))
+
+    await act(async () => {
+      result.current.run('cap', {})
+      await Promise.resolve()
+    })
+
+    expect(result.current.state.phase).toBe('failed')
+    expect((result.current.state as { phase: 'failed'; error: string }).error).toContain('net error')
+  })
+
+  it('transitions to failed when poll returns failed status', async () => {
+    const client = makeClient({
+      pollExecution: vi.fn().mockResolvedValue({
+        execution_id: 'exec-1',
+        status: 'failed',
+        error: 'boom',
+      } as ExecutionResult),
+    })
+    const { result } = renderHook(() => useExecution(client, 'ws', POLL_MS))
+
+    act(() => { result.current.run('cap', {}) })
+    await act(async () => { await Promise.resolve() })
+    await act(async () => { await vi.advanceTimersByTimeAsync(POLL_MS) })
+
+    expect(result.current.state.phase).toBe('failed')
+    expect((result.current.state as { phase: 'failed'; error: string }).error).toBe('boom')
+  })
+})
diff --git a/apps/youaskm3/web-react/src/hooks/useExecution.ts b/apps/youaskm3/web-react/src/hooks/useExecution.ts
new file mode 100644
index 0000000..03c712d
--- /dev/null
+++ b/apps/youaskm3/web-react/src/hooks/useExecution.ts
@@ -0,0 +1,61 @@
+import { useState, useCallback, useRef } from 'react'
+import { type TraverseClient, type ExecutionResult, type TraceEvent } from '../client/traverseClient'
+
+export type ExecutionState =
+  | { phase: 'idle' }
+  | { phase: 'loading' }
+  | { phase: 'polling'; executionId: string }
+  | { phase: 'succeeded'; result: ExecutionResult; trace: TraceEvent[] }
+  | { phase: 'failed'; error: string }
+
+const POLL_TERMINAL: readonly string[] = ['succeeded', 'failed']
+
+export function useExecution(client: TraverseClient, workspaceId: string, pollIntervalMs = 1000) {
+  const [state, setState] = useState<ExecutionState>({ phase: 'idle' })
+  const pollRef = useRef<ReturnType<typeof setInterval> | null>(null)
+
+  const stopPolling = useCallback(() => {
+    if (pollRef.current !== null) {
+      clearInterval(pollRef.current)
+      pollRef.current = null
+    }
+  }, [])
+
+  const run = useCallback(
+    async (capability: string, input: unknown) => {
+      stopPolling()
+      setState({ phase: 'loading' })
+
+      let executionId: string
+      try {
+        executionId = await client.execute(workspaceId, capability, input)
+      } catch (e) {
+        setState({ phase: 'failed', error: String(e) })
+        return
+      }
+
+      setState({ phase: 'polling', executionId })
+
+      pollRef.current = setInterval(async () => {
+        try {
+          const result = await client.pollExecution(workspaceId, executionId)
+          if (POLL_TERMINAL.includes(result.status)) {
+            stopPolling()
+            const trace = await client.fetchTrace(workspaceId, executionId).catch(() => [])
+            if (result.status === 'succeeded') {
+              setState({ phase: 'succeeded', result, trace })
+            } else {
+              setState({ phase: 'failed', error: result.error ?? 'execution failed' })
+            }
+          }
+        } catch (e) {
+          stopPolling()
+          setState({ phase: 'failed', error: String(e) })
+        }
+      }, pollIntervalMs)
+    },
+    [client, workspaceId, stopPolling, pollIntervalMs],
+  )
+
+  return { state, run }
+}