---
source: ~/Developer/virfield/
confidence: 1.0
namespace: work
last_updated: 2026-04-28
tags: [ui-testing, vm, virfield, ddg-vm, xcode]
---

# VM UI Testing — virfield / ddg-vm MCP

**What it is**: macOS VM lifecycle console + MCP server for AI-driven UI test automation.  
**How it runs**: Golden image (built once) → APFS CoW clone per test session → run → delete.  
**MCP config**: `~/Developer/virfield/server/mcp-server.ts` (configured in `.claude/.mcp.json` as `ddg-vm`)  
**Web UI**: `http://localhost:5173` (requires `npm run dev` in `~/Developer/virfield/`)

---

## Standard Agent Flow for UI Tests

### Step 1 — Start a session (single call)

```
vm_prepare_session()
```

This does everything in sequence: clone golden → start VM → wait for SSH → wait for Peekaboo ready.  
Returns `{ vmName, ip }`. Use `vmName` in all subsequent calls.

### Step 2 — Run XCUITests

```
run_tests(
  vm_id: vmName,
  scheme: "DuckDuckGo macOS",
  workspace: "<VMShare path to DuckDuckGo-macOS.xcworkspace>"
)
```

Returns `run_id` immediately. Poll with:

```
get_test_run_status(vm_id: vmName, run_id: run_id)
get_test_results(vm_id: vmName, run_id: run_id)
```

Uses pre-built `xctestrun` from `VMShare/DerivedData` — build must happen on host first.

### Step 3 — Inspect failures

```
peekaboo_image(vm_id: vmName)          # screenshot
peekaboo_see(vm_id: vmName, app: "...")  # AX tree
ax_snapshot(vm_id: vmName, app: "...", name: "before")
ax_diff_last(vm_id: vmName, app: "...")  # what changed
get_crash_reports(vm_id: vmName)       # crash logs
get_log_stream(vm_id: vmName, path: "...", lines: 50)
```

### Step 4 — Cleanup (ALWAYS — especially from Executor)

```
vm_stop(vm_id: vmName)
vm_delete(vm_id: vmName)
```

**Executor must call these before removing its worktree.** Never leave orphaned VMs.

---

## All MCP Tools

| Tool | Purpose |
|------|---------|
| `vm_list` | List all VMs with state, IP, checklist status |
| `vm_prepare_session` | **Main entry point** — clone + start + wait for ready |
| `vm_start` | Start a VM (optionally clone from golden first) |
| `vm_stop` | Stop a running VM |
| `vm_clone_golden` | APFS CoW clone from golden image |
| `vm_delete` | Delete a VM (run VMs only, never golden) |
| `vm_get_ip` | Get IP of running VM |
| `vm_status` | Full status including Peekaboo connection state |
| `vm_ssh_exec` | Run a shell command in VM via SSH |
| `run_tests` | Launch XCUITests in VM (returns run_id immediately) |
| `get_test_run_status` | Poll whether xcodebuild is still running |
| `get_test_results` | Parse test result artifacts for a run_id |
| `get_crash_reports` | Read crash reports from VM |
| `get_log_stream` | Tail a log file from VM |
| `peekaboo_see` | Dump AX accessibility tree for an app |
| `peekaboo_image` | Screenshot from VM |
| `peekaboo_click` | Click by query / element ID / coords |
| `peekaboo_type` | Type text in VM |
| `peekaboo_hotkey` | Send hotkey (e.g. cmd+s) |
| `peekaboo_scroll` | Scroll in VM |
| `peekaboo_list_apps` | List running apps in VM |
| `peekaboo_permissions` | Check Screen Recording / Accessibility permissions |
| `ax_snapshot` | Take named AX snapshot for later diff |
| `ax_diff_last` | Diff current AX state vs last snapshot |
| `ax_diff` | Diff two named snapshots by ID |
| `ax_query` | Query elements from latest snapshot |
| `vm_build_golden` | Build golden VM from IPSW (full 4-phase pipeline) |
| `vm_get_build_state` | Poll golden build progress |
| `vm_list_recordings` | List VNC recordings from build logs |
| `vm_list_screenshots` | List screenshots from build logs |

---

## Executor Integration

When the Executor needs UI tests (bug requires visual verification):

1. Call `vm_prepare_session()` after build succeeds
2. Call `run_tests()` with the scheme
3. Poll `get_test_run_status()` / `get_test_results()`
4. On failure: capture `peekaboo_image()` + `get_crash_reports()` for diagnosis
5. **Always** `vm_stop()` + `vm_delete()` before worktree cleanup

See also: `ui-testing.md` — Swift UITestCase patterns, feature flag setup, test structure.

---

## Notes

- VMs require Apple Silicon + lume (`brew install trycua/tap/lume`)
- Golden image must be built and provisioned before test runs work
- `run_tests` uses pre-built xctestrun — **build on host before running in VM**
- Peekaboo (AX/screenshot proxy) must be running inside the VM — `vm_prepare_session` handles this