| name | app-control |
| description | Drive a specific named macOS app via raw input bypassing the Accessibility tree |
| compatibility | Designed for Vellum personal assistants |
| metadata | {"emoji":"🎯","vellum":{"display-name":"App Control","category":"system","feature-flag":"app-control","activation-hints":["User explicitly directs the assistant to drive a specific named app via raw input (emulator, game, OpenGL canvas, custom-rendered Electron app)","User says the macOS Accessibility tree is unhelpful or empty for the target app"],"avoid-when":["Task can be done via the computer-use skill (general macOS UI navigation)","Task can be done via a CLI / API alternative"]}} |
This skill exposes the app_control_* proxy tools for driving a single
named macOS application via raw input — keyboard, mouse, screenshot — that
bypasses the system Accessibility tree. Use it only when explicitly directed
to a specific app where the AX tree is unhelpful (emulators, games, OpenGL
canvases, custom-rendered Electron apps). For general macOS UI navigation
prefer the computer-use skill.
Tools in this skill are proxy tools — execution is forwarded to the connected
macOS client, never handled locally by the assistant.
Cadence
Take 2-3 actions per turn, then yield with a short narration so the user can
interject. Do not chain long sequences without surfacing what you are doing.
Always observe before acting
Call app_control_observe before your first input action whenever the screen
state matters (e.g. you need to know what is on screen, where a UI element is,
or whether the app is even running). Re-observe after actions that may have
moved the window or changed visibility.
observe waits a short settle delay (default ~200ms) before capturing so the
target app and the WindowServer can flush pending input and composite a fresh
frame. If the captured screenshot looks one input behind the latest state
(common with emulators or other slow-feedback apps), pass a larger
settle_ms. For static UIs where you just want a quick snapshot, pass
settle_ms: 0 to skip the wait.
Input choice
- Prefer
app_control_sequence over multiple back-to-back app_control_press
calls when sending an ordered batch of presses (e.g. menu navigation,
repeated movement). Sequence runs in a single round-trip — the target app is
activated once at the start and the keys are sent serially without any
window for keyboard focus to drift to another app between presses. Each step
may carry its own duration_ms (hold) and gap_ms (pause after).
- Prefer
app_control_combo over rapid sequential app_control_press for
simultaneous inputs (e.g. cmd+shift+4). combo holds every key at once;
sequential presses interleave key-down and key-up events.
- Use
app_control_type for literal text into a focused field.
Coordinate caveat
app_control_click and app_control_drag use window-relative coordinates.
The window may move or resize between observation and click — if you are
uncertain whether the window has shifted, re-observe first.
App targeting
Use bundle IDs (e.g. com.example.app) when possible — they are the most
reliable identifier. Fall back to localized process names if a bundle ID is
unavailable.
Ending the session
Call app_control_stop when you are done. Do not auto-quit the controlled
app — stop only ends the app-control session, leaving the app running.
