CtrlK
BlogDocsLog inGet started
Tessl Logo

vm-lab

Parallels macOS VM lab: GUI automation, Peekaboo, TCC, Ghostty.

66

Quality

78%

Does it follow best practices?

Run evals on this skill

Adds up to 20 points to the overall score

View guide

SecuritybySnyk

Passed

No findings from the security scan

Fix and improve this skill with Tessl

tessl review fix ./skills/vm-lab/SKILL.md
SKILL.md
Quality
Evals
Security

VM Lab

Use this when the task needs a clean macOS VM to test GUI automation, TCC prompts, screenshot capture, clicking, typing, performance, or "two-way validation" of Peekaboo-like tools.

Core idea: run the tool under test inside the guest, but verify it from outside the guest with Parallels screenshots and host-side observations. Do not close apps you do not own.

Safety Rules

  • Treat the VM snapshot as disposable, not the host.
  • Never print secrets. If op is needed, follow the 1Password skill and run it only inside tmux.
  • Prefer fresh app windows you create yourself: TextEdit, a local HTML test page, or a small test app.
  • Avoid modifying host state except temporary screenshots under /tmp.
  • For git repos inside the VM, use HTTPS remotes and normal branch discipline.

VM Discovery

List VMs:

prlctl list --all

Get VM status/IP:

prlctl list --info "macOS Tahoe"

Run guest commands as Peter:

prlctl exec "macOS Tahoe" \
  'sudo -u steipete -H /bin/zsh -lc '\''source ~/.zprofile 2>/dev/null || true; uname -a'\'''

Capture an independent host-side screenshot:

prlctl capture "macOS Tahoe" --file /tmp/vm-reference.png
sips -g pixelWidth -g pixelHeight /tmp/vm-reference.png

TCC / GUI Attribution

For macOS Screen Recording and Accessibility, the responsible process matters.

  • prlctl exec is headless and can fail to produce useful Screen Recording attribution.
  • Launch the test command from a visible terminal app in the guest when Screen Recording is involved.
  • Ghostty works as a GUI terminal if installed.
  • After a first failed capture, check System Settings > Privacy & Security > Screen & System Audio Recording.
  • permissions status run through prlctl exec may still report Screen Recording false after Ghostty is allowed; validate Screen Recording by rerunning the capture from Ghostty.

Open the Screen Recording pane:

prlctl exec "macOS Tahoe" \
  'sudo -u steipete -H open "x-apple.systempreferences:com.apple.preference.security?Privacy_ScreenCapture"'

Open Ghostty:

prlctl exec "macOS Tahoe" 'sudo -u steipete -H open -a Ghostty'

Running Commands Through Ghostty

Best path: create a guest script with prlctl exec, open/focus Ghostty, then type only a short launcher path into the visible terminal.

Guest script pattern:

prlctl exec "macOS Tahoe" 'sudo -u steipete -H /bin/zsh -lc '\''cat > /tmp/run-vm-lab.zsh <<EOF
#!/bin/zsh
source ~/.zprofile 2>/dev/null || true
cd ~/Projects/Peekaboo || exit 1
Apps/CLI/.build/debug/peekaboo image --path /tmp/peekaboo-vm.png --json
rc=$?
echo "EXIT:$rc"
[ -f /tmp/peekaboo-vm.png ] && sips -g pixelWidth -g pixelHeight /tmp/peekaboo-vm.png
echo "Press return to close..."
read _
exit $rc
EOF
chmod +x /tmp/run-vm-lab.zsh
ln -sf /tmp/run-vm-lab.zsh /tmp/r
open -a Ghostty'\'''

Then link the launcher into Ghostty's home directory and type ./r with scripts/parallels_type.py. This avoids unreliable path characters in Parallels key injection.

prlctl exec "macOS Tahoe" \
  "sudo -u steipete -H /bin/zsh -lc 'ln -sf /tmp/run-vm-lab.zsh ~/r'"
python3 skills/vm-lab/scripts/parallels_type.py "macOS Tahoe" $'./r\n'

Avoid long command typing. Parallels key injection uses its own key-code table and can be layout-sensitive.

Known Pitfalls

  • macOS clipboard APIs may fail from prlctl exec; pbcopy, AppleScript clipboard, and Peekaboo paste can all fail in headless guest context.
  • open -na Ghostty.app --args -e ... may only focus an existing Ghostty window on macOS; do not assume it runs the command.
  • prlctl exec may re-join argv through a guest shell; for complex payloads, pass one fully shell-quoted command string or create the file with a tiny Python writer.
  • Parallels send-key-event --key uses Parallels key values, not macOS virtual key codes.
  • For normal typing, send prlctl send-key-event <vm> --key <key> with no --event; explicit press/release can repeat or stick. Return is an exception: use press then release.
  • Prefer one prlctl send-key-event --json batch over many separate send-key-event processes; separate calls can drift under focus/latency.
  • Use PRL_KEY_ENTER = 36, PRL_KEY_SLASH = 61, PRL_KEY_R = 27, PRL_KEY_T = 28, PRL_KEY_M = 58, PRL_KEY_P = 33.
  • If keystrokes produce garbage, send Return to clear the line, create a shorter launcher, then retry.
  • If Peekaboo permission probes hang with Screen Recording missing and emit SWIFT TASK CONTINUATION MISUSE, record it as a product bug; do not confuse it with the VM harness.

Two-Way Validation

For each GUI action, verify through two independent signals:

  • Tool-under-test output: JSON, screenshot file, AX result, or app state.
  • External verifier: prlctl capture, host-side image inspection, file content in guest, or process/window state.

Examples:

  • Screenshot: compare Peekaboo image dimensions/content against prlctl capture.
  • Click: use Peekaboo to click a test button, then verify both guest app state and host screenshot.
  • Type: use Peekaboo to type into a controlled text field, then verify AX value and host screenshot.
  • Performance: wrap commands with /usr/bin/time -p; repeat cold/warm runs; keep outputs in /tmp.

Peekaboo VM Baseline

Inside guest:

cd ~/Projects/Peekaboo
git pull --recurse-submodules
swift build --package-path Apps/CLI
Apps/CLI/.build/debug/peekaboo --version
Apps/CLI/.build/debug/peekaboo permissions status --json

Host-side reference capture:

prlctl capture "macOS Tahoe" --file /tmp/vm-prlctl-reference.png

Guest-side Peekaboo capture through Ghostty:

/tmp/r

Compare:

prlctl exec "macOS Tahoe" \
  'sudo -u steipete -H /bin/zsh -lc '\''sips -g pixelWidth -g pixelHeight /tmp/peekaboo-vm.png'\'''
sips -g pixelWidth -g pixelHeight /tmp/vm-prlctl-reference.png

Reporting

When handing off, include only:

  • VM name and OS build.
  • repo commit tested.
  • permission state.
  • commands that passed/failed.
  • independent verifier result.
  • product bugs discovered.
Repository
steipete/agent-scripts
Last updated
First committed

Is this your skill?

If you maintain this skill, you can claim it as your own. Once claimed, you can manage eval scenarios, bundle related skills, attach documentation or rules, and ensure cross-agent compatibility.