---
name: cua-driver
description: Drive a native macOS app via the cua-driver CLI (default) or MCP server — snapshot its AX tree, click/type/scroll by element_index, verify via re-snapshot. Use when the user asks you to operate, drive, automate, or perform a GUI task in a real macOS application on the host (e.g. "open a file in TextEdit", "navigate to /Applications in Finder", "click the Save button in Numbers").
---

# cua-driver

Orchestrates macOS app automation via `cua-driver`. Whenever a user
asks to drive a native macOS app, follow the loop in this skill rather
than calling tools ad-hoc — the snapshot-before-action invariant is not
optional and silently breaks if you skip it.

## The no-foreground contract — read this first

**The user's frontmost app MUST NOT change.** This is the whole
reason cua-driver exists. Users pay for the right to keep typing in
their editor while an agent drives another app in the background.
Violate this rule and every other nice property the driver gives
you (no cursor warp, no Space switch, no window raise) stops
mattering — you just shipped the Accessibility Inspector with extra
steps.

Before running any shell command, ask: **"does this raise,
activate, foreground, or make-key any app?"** If yes, don't run it.
Every one of the commands below activates the target on macOS and
is therefore forbidden unless the user **explicitly** asked for
frontmost state:

- **Every form of the `open` CLI — `open -a <App>`, `open -b
  <bundle-id>`, `open <file>`, `open <path-to-App.app>`, `open
  <url>` — always activates.** macOS routes all forms through
  LaunchServices, which unhides and foregrounds the target
  regardless of whether you passed an app name, a bundle id, a
  document, a URL, or the bundle path itself. The activation
  happens even when the only intent was "start the process."
  **Never use `open` for any app launch.** This includes launching
  a just-built .app from a local build dir (e.g. `open
  build/Build/Products/Debug/MyApp.app`) — resolve the
  `CFBundleIdentifier` from `Info.plist` and use `launch_app`
  with that id. See "The narrow carve-out" below for why
  `launch_app` is safe even when the app internally calls
  `NSApp.activate`.
- `osascript -e 'tell application "X" to activate'` —
  activates by design. Same for `... to open <file>`,
  `... to launch`, and anything with `activate` in the tell block.
- `osascript -e 'tell application "System Events" to ... frontmost'`
  in a mutating form (setting `frontmost` rather than reading it).
- AppleScript files that invoke `activate`, `launch`, or `open`
  against the target app.
- `cliclick` (moves the user's real cursor to the target coords
  before clicking — a focus-steal-equivalent even if the app's
  window state is unchanged).
- `CGEventPost` with `cghidEventTap` targeting a coordinate over
  a different app's window (warps the cursor, possibly activates
  on hit).
- `AppleScriptTask`, `NSAppleScript`, `Process` wrapping `osascript`
  that contains any of the above.
- `NSRunningApplication.activate(options:)` called from your own
  helper binary — same class.
- Dock clicks and any `open` invocation (see the first bullet —
  every form of `open` goes through LaunchServices which
  activates, full stop).
- **Keyboard shortcuts that semantically mean "focus here" —
  most notably Chrome / Safari / Arc's `⌘L` (focus omnibox) and
  Finder's `⌘⇧G` (Go to Folder).** These aren't pure key events —
  the receiving app interprets "user wants to type here" as
  activation intent and raises its window to be key. Even when
  delivered to a backgrounded pid via `hotkey`, the downstream app
  pulls focus. **For omnibox navigation specifically**, the correct
  path is `launch_app({bundle_id: "com.google.Chrome", urls:
  ["https://…"]})` — no omnibox dance, no `⌘L`, no focus-steal. Do
  NOT try `set_value` on the omnibox: Chrome's commit logic requires
  a "user-typed" signal that neither an AX value write nor
  `CGEvent.postToPid` keystrokes supply from a backgrounded pid —
  the URL lands in the field but Return fires as a no-op. See
  `WEB_APPS.md` → "Navigate to a URL" for the full pattern. The
  general principle: a shortcut that says "put my cursor inside this
  app" is a focus-steal; a shortcut that says "do this thing" (copy,
  save, quit) is fine.
- **Tab-switching shortcuts in browsers (`⌘1..⌘9`, `⌘]`, `⌘[`,
  `⌘⇧[`, `⌘⇧]`) are visibly disruptive even when delivered to a
  backgrounded pid.** The app's key handler processes the shortcut,
  the window re-renders the new tab's content, the user sees their
  tabs flipping. There is no AX-only workaround: page content (HTML,
  form state, `AXWebArea`) populates only for the focused tab;
  inspecting a background tab requires activating it, which is the
  visible flip. Observed with Dia; the same mechanic applies to every
  Chromium-family browser (Chrome, Arc, Brave, Edge).

  **Prefer the windows-over-tabs pattern**: for each URL you need to
  drive backgrounded, use `launch_app({bundle_id, urls: [url]})` —
  browsers open each URL in a new **window**. Each window has its own
  `window_id`, its own AX tree, and can be inspected / interacted with
  via `element_index` without activating or switching anything. Tabs
  are a UX grouping for humans; cua-driver workflows should default to
  windows. See `WEB_APPS.md` → "Tabs vs windows" for the full pattern.

  Tab-title enumeration (read-only) IS safe — walk a window's toolbar
  AX tree for `AXTab` / `AXRadioButton` children and read their
  `AXTitle`s. Tab switching (activating one) is not.

Reading frontmost state is fine (`osascript -e 'tell application
"System Events" to get name of first application process whose
frontmost is true'`). Mutating it is not.

**Corollary — the AXMenuBar rule.** `AXMenuBarItem` + AXPick
dispatches at the AX layer regardless of which app is frontmost,
but macOS's on-screen menu bar always belongs to the frontmost
app. If you drive a *backgrounded* app's menu bar, the AX call
succeeds but the viewer sees the dispatch rendered over the
*frontmost* app's menu bar — confusing in any observed session and
routinely a silent no-op too, because action menu items go
`DISABLED` when their owning app isn't the key window. **So: only
use menu-bar navigation when the target is already frontmost.** For
backgrounded targets, read state via in-window AX (window title,
toolbar `AXStaticText`) and dispatch via in-window `element_index`
or pixel clicks — both paths are frontmost-insensitive. Full
rationale in "Navigating native menu bars" below.

**"Open \<app\>" in user speech means launch, not activate.**
`cua-driver launch_app` is the one correct path for process
startup — it's idempotent (no-op on a running app), returns the
pid, and has an internal `FocusRestoreGuard` that catches
`NSApp.activate(ignoringOtherApps:)` calls the target makes during
`application(_:open:)` and clobbers the frontmost back to what it
was before the launch. That guard is why `launch_app` with `urls`
(e.g. `{"bundle_id": "com.colliderli.iina", "urls": ["~/video.mp4"]}`)
is safe even for apps that normally foreground on media-load
(Chrome, Electron, media players).

## Defaults — always prefer cua-driver over shell shims

**Default transport is the `cua-driver` CLI** — `Bash` shelling out
to `cua-driver <tool-name> '<JSON-args>'`. MCP tools (prefix
`mcp__cua-driver__*`) only when the user explicitly asks for them.
CLI wins because it picks up rebuilds instantly, failures are
easier to diagnose, and there's no per-tool schema-load overhead.

Every reference to `click(...)`, `get_window_state(...)` etc. in this
skill means `cua-driver click '{...}'` — translate to MCP form only
when MCP is requested.

### Claude Code computer-use compatibility mode

For normal Claude Code use, keep the default CLI or `cua-driver` MCP server path above. If the user explicitly wants Claude Code's vision/computer-use-style flow, they can register:

```bash
claude mcp add --transport stdio cua-computer-use -- cua-driver mcp --claude-code-computer-use-compat
```

Observation: Claude Code vision flows appear to treat a screenshot MCP tool as the image-grounding anchor. This compatibility mode keeps the normal CuaDriver tools and changes only `screenshot`. The compatibility `screenshot` requires `pid` and `window_id`, captures only that target window, and returns the window-local pixel coordinate frame. Start with `launch_app` or `list_windows`, then call `screenshot({pid, window_id})`; do not assume desktop coordinates or a full-screen capture.

Use MCP for this Claude Code vision/computer-use-style path. Do not shell out to `cua-driver screenshot` as a substitute: CLI screenshots still work as CuaDriver calls, but they do not expose the `mcp__cua-computer-use__screenshot` tool name that Claude Code appears to use as the image-grounding cue.

Intent → tool mapping. If you find yourself reaching for the right
column, something has gone wrong — re-read "The no-foreground
contract" above:

| Intent | Use | Don't use |
|---|---|---|
| Open / launch an app | `launch_app({bundle_id})` or `launch_app({bundle_id, urls:[...]})` | `open -a`, `osascript 'tell app … to launch/activate/open'` |
| Find a pid | `list_apps` or `launch_app`'s return | `pgrep`, `ps`, `osascript frontmost` |
| Enumerate an app's windows | `list_windows({pid})` — or read the `windows` array `launch_app` already returns | `osascript 'every window of app …'` |
| Click / type / scroll / keys | `click`, `type_text`, `scroll`, `press_key`, `hotkey` | `osascript`, `cliclick`, raw `CGEvent`, `open <url>` |
| Drag / drag-and-drop / marquee select | `drag({pid, from_x, from_y, to_x, to_y})` (pixel-only — macOS AX has no semantic drag) | `cliclick dd:`, `osascript drag` |
| Screenshot | `screenshot` or the PNG in `get_window_state` | `screencapture` |
| Quit an app | ask the user first, then `hotkey({pid, keys:["cmd","q"]})` | `kill`, `killall`, `pkill` |
| Hand a file/URL to an app | `launch_app({bundle_id, urls:[<path>]})` | `open -a <App> <path>`, `open <url>` |

### The narrow carve-out

The **only** legitimate use of `osascript -e 'tell app X to
activate'` is when the user **explicitly** asked for frontmost
state ("bring Chrome to the front", "make it frontmost", "I want
to see X"). Reaching for it because a tool call returned something
confusing is wrong — that's the skill's classic foot-in-the-door
failure mode and it steals focus every time.

When a cua-driver call surprises you, diagnose cua-driver first:

- **Tiny screenshot / empty `tree_markdown`?** Check
  `cua-driver get_config` → `capture_mode`. Default `"som"` returns
  both the AX tree and screenshot. `"vision"` omits the AX tree
  (PNG only), `"ax"` omits the PNG. If a snapshot lacks a tree,
  `capture_mode` is almost certainly `"vision"` — either reason
  purely from the PNG or flip to `"som"` / `"ax"` via `set_config`.
- **`has_screenshot: false`?** The window capture failed (transient
  race against a close, or the window has no backing store yet).
  Re-snapshot; if persistent, pick a different `window_id` via
  `list_windows`.
- **`Invalid element_index` / `No cached AX state`?** You either
  skipped `get_window_state` this turn or passed a different
  `window_id` than the one the snapshot cached against. The cache
  is keyed on `(pid, window_id)` — indices don't carry across
  windows of the same app. Re-snapshot with the same window_id
  you're about to click in.
- **Sparse Chromium AX tree?** Retry `get_window_state` once — the
  tree populates on second call.

Only after those are ruled out, and only if the user's action
genuinely needs frontmost state, fall through to the activate
fallback. Always name the focus steal in your response ("I'll
briefly bring Chrome to the front because …").

### Self-check pattern

Before every `Bash` call whose command line touches any macOS app
(launching, opening, clicking, typing, scripting, screenshotting),
run the self-check:

1. **Does this command foreground the target?** If yes — stop and
   translate to the cua-driver equivalent from the mapping table.
2. **Does this command move the user's real cursor?** (`cliclick`,
   any `CGEventPost` at `cghidEventTap` over another app's window).
   If yes — stop; use `click({pid, x, y})` which routes per-pid
   via SkyLight and never warps the cursor.
3. **Does this command bypass cua-driver entirely?** (`osascript`
   mutating GUI state, AppleScript files, external helpers.) If
   yes — stop; find the cua-driver tool that does the intent.

If all three are "no," the command is safe. If you can't answer,
default to stop and ask rather than proceed. A single `open -a`
run by accident kills the demo, the trust, and the user's in-flight
editor state.

## Prerequisites — check before starting

1. `cua-driver` is on `$PATH` (`which cua-driver`). If not, point the
   user at `scripts/install-local.sh` and stop.
2. Run `cua-driver check_permissions` (with the daemon up — see step 3).
   The default behavior also raises the system permission dialogs for
   any missing grants, so the user can grant on the spot. If either
   grant still reads `false` after that (user dismissed the dialog),
   tell them to open System Settings → Privacy & Security and grant
   Accessibility and Screen Recording to `CuaDriver.app`, then stop.
   Pass `'{"prompt":false}'` for a purely read-only status check that
   won't steal focus.
3. Start the daemon with `open -n -g -a CuaDriver --args serve` (the
   recommended form — goes through LaunchServices so TCC attributes
   the process to CuaDriver.app). `cua-driver serve &` also works;
   the CLI auto-relaunches through `open -n -g -a CuaDriver` when it
   detects a wrong-TCC context (any IDE-spawned shell: Claude Code,
   Cursor, VS Code, Conductor). Verify with `cua-driver status`.

## Using cua-driver from the shell

Tool names are `snake_case`, management subcommands are
`kebab-case` — no ambiguity. Tools invoked as `cua-driver
<tool-name> '<JSON-args>'`. Management subcommands:

- `open -n -g -a CuaDriver --args serve` — start persistent daemon
  (**required** for `element_index` workflows; without it each CLI
  invocation spawns a fresh process and the per-pid element cache
  dies between calls). `cua-driver serve &` also works — the CLI
  auto-relaunches via `open` when the shell's TCC context is wrong.
  Pass `--no-relaunch` / `CUA_DRIVER_NO_RELAUNCH=1` to opt out.
- `cua-driver stop` / `status`
- `cua-driver list-tools`, `describe <tool>`
- `cua-driver recording start|stop|status` — see `RECORDING.md`

Canonical multi-step workflow:

```
open -n -g -a CuaDriver --args serve
cua-driver launch_app '{"bundle_id":"com.apple.calculator"}'
# → {pid: 844, windows: [{window_id: 10725, ...}]}
cua-driver get_window_state '{"pid":844,"window_id":10725}'
cua-driver click '{"pid":844,"window_id":10725,"element_index":14}'
cua-driver stop
```

## Agent cursor overlay

Visual cursor overlay for demos and screen recordings. Default:
enabled. Toggle with `cua-driver set_agent_cursor_enabled
'{"enabled":true|false}'`. A triangle pointer Bezier-glides to each
click target, ring-ripples on landing, idle-hides after ~1.5s.
Motion knobs: `set_agent_cursor_motion` takes any subset of
`start_handle`, `end_handle`, `arc_size`, `arc_flow`, `spring` —
tuneable at runtime, persisted to config.

Requires an AppKit runloop, which `cua-driver serve` / `mcp`
bootstraps. One-shot CLI invocations skip the overlay entirely.

## The core invariant — snapshot before AND after every action

**Every action MUST be bracketed by `get_window_state(pid, window_id)`**:

- **Before** — the pre-action snapshot resolves the `element_index`
  you're about to use. Indices from previous turns are stale; the
  server replaces the element index map on every snapshot, keyed
  on `(pid, window_id)`. Indices from turn N don't resolve in turn
  N+1, and indices from window A don't resolve against window B of
  the same app. Skip this and element-indexed actions fail with
  `No cached AX state`.
- **After** — the post-action snapshot verifies the action actually
  landed. Without it you can't tell a silent no-op from a real
  effect. The AX tree change (new value, new window, disappeared
  menu, disabled button, etc.) is your evidence that the action
  fired. If nothing changed, the action probably failed silently —
  say so, don't assume success.

This applies to pixel clicks too — re-snapshot after to confirm the
click landed on the intended target.

### Why window selection is the caller's job now

`get_app_state` used to pick a window for you via a max-area heuristic
that returned the wrong surface on apps with large off-screen utility
panels. Concrete reproducer: IINA's OpenSubtitles helper (600×432
off-screen) out-area'd the visible 320×240 player window, so
`get_app_state(pid)` screenshot'd the invisible panel and clicks landed
there silently. The new `get_window_state(pid, window_id)` makes the
caller name the window explicitly — the driver validates that the
window belongs to the pid and is on the current Space, then snapshots
exactly what was asked for. Enumerate candidates via `list_windows` or
read the `windows` array `launch_app` already returns.

## Behavior matrix

Two orthogonal axes shape what the agent can do.

**capture_mode → addressing mode**

| `capture_mode` | `get_window_state` returns | Use for actions |
|---|---|---|
| **`som`** (default) | tree + screenshot | `element_index` preferred; pixel fallback |
| **`ax`** | tree only (no PNG) | `element_index` only |
| **`vision`** | PNG only (no tree) | pixel only — see [SCREENSHOT.md](./SCREENSHOT.md) |

`vision` was renamed from `screenshot` — the old name still decodes
as a deprecated alias, so an on-disk `"capture_mode": "screenshot"`
keeps working. Default is `som` so element_index clicks work the
first time a user calls `get_window_state`; the other modes are
opt-in when the caller specifically doesn't want one half of the
work. Note the tool named `screenshot` is separate (raw PNG, no AX
walk) and unrelated to the capture mode.

When a snapshot looks wrong (tiny screenshot / empty tree), check
`cua-driver get_config` for `capture_mode` before anything else.

Pure-vision mode has its own caveats — Claude Code's vision
pipeline downsamples dense text aggressively, so pixel grounding
takes multiple correction cycles on text-heavy UIs. Read
[SCREENSHOT.md](./SCREENSHOT.md) before driving anything in that
mode; it documents the iterate/annotate/verify recipe plus the
JPEG-over-PNG finding.

**Window state → what works**

| state | `get_window_state` | `click`/`set_value` (AX) | `press_key` commit (Return/Space/Tab) | pixel click |
|---|---|---|---|---|
| frontmost | ✅ | ✅ | ✅ | ✅ |
| backgrounded / visible | ✅ | ✅ | ✅ | ✅ |
| **minimized** (Dock genie) | ✅ | ✅ (no deminiaturize — AX actions fire on the minimized window in place) | ❌ silent no-op / system beep — use `set_value` or click equivalent | ❌ no on-screen bounds |
| hidden (`hides=true` / `NSApp.hide`) | ✅ | ✅ | depends | ❌ |
| on another Space | ⚠️ AX tree often stripped to menu-bar-only on SwiftUI apps (System Settings) — AppKit apps usually fine. Response carries `off_space: true` + `window_space_ids` so you can detect it | ✅ | ✅ | ❌ window not in current-Space list |

**Critical cell — minimized + keyboard commit.** The keystroke
reaches the app but AX focus doesn't propagate to renderer focus on
a minimized window. Workarounds in order of preference:
`set_value` to write the field's entire value directly, or AX-click
a commit-equivalent button (Go, Submit, checkbox). Tell the user
the window needs to un-minimize only as a last resort.

## The canonical loop

```
launch_app(target)
  → pick window_id from the returned `windows` array
    (or call list_windows(pid) separately)
  → get_window_state(pid, window_id)
    → [act]  # every action also takes (pid, window_id)
  → get_window_state(pid, window_id) → verify
```

`launch_app` now returns a `windows` array alongside the pid, so the
common case collapses to two calls (`launch_app` → `get_window_state`)
without a separate `list_windows` hop.

### 1. Resolve target pid — always via `launch_app`

**Always start with `launch_app`**, whether or not the target is already
running. It's idempotent (relaunching returns the existing pid with no
side effects) and gives you the pid in one call — no `list_apps` hop.

- `launch_app({bundle_id: "com.apple.finder"})` — preferred, unambiguous.
- `launch_app({name: "Calculator"})` — when bundle_id isn't known.

`launch_app` is a **hidden-launch primitive by design** — that's the
entire point of cua-driver: agents drive apps in the background while
the user keeps typing in their real foreground app. The target's
window is initialized (AX tree fully populated, clickable via
`element_index`, the pid appears in `list_apps`) but not drawn on
screen. The driver never activates or unhides apps on its own; that
would violate the no-foreground contract the whole driver exists to
protect.

If the user explicitly wants the window visible (usually for a demo
or recording), they unhide it themselves — Dock click, Cmd-Tab, or
Spotlight. Do not reach for `open` / `osascript activate` as a
shortcut to make the window visible; those paths break the backgrounded
invariant on every call, not just the call that "needed" the
foreground. Say out loud what the user needs to do ("click the
Todo app in your Dock to bring it forward") and let them do it.

Never shell out to **any** form of `open` (including `open
<path-to-App.app>` for a just-built binary — resolve the bundle id
from `Info.plist` and use `launch_app` with that), `osascript 'tell
app … to launch/open'`, or similar. Those paths activate the target,
bypass the driver's focus-restore guard, and require a Bash
permission prompt the agent loop shouldn't be burning on app launch.
See "Prefer cua-driver tools over shell shims" above for the full
intent → tool mapping.

`list_apps` is for app-level discovery (answering "what's installed /
running / frontmost?") — not part of the core action loop. Skip it in
the loop. For **window-level** questions — "does this app have a
visible window?", "which Space is this window on?", "which of this
pid's windows is the main one?" — call `list_windows` instead; the
app record doesn't carry window state on purpose. In the common
single-window case you can skip `list_windows` entirely and read the
`windows` array that `launch_app` already returned.

### 2. Snapshot and act by element_index

Call `get_window_state({pid, window_id})` with the `window_id` from
`launch_app`'s `windows` array (or a fresh `list_windows({pid})` if
you're interacting with a long-lived process). The default `som`
capture_mode returns **both the AX tree and screenshot**, so the
canonical loop works immediately without any config change. The rest
of this section walks through `som` mode. If you're in `vision` mode
(PNG only, no AX tree), flip back: `cua-driver set_config '{"key":
"capture_mode", "value": "som"}'`.

In `som` mode (the default) the response carries:

- `tree_markdown` — every actionable element tagged `[N]`. That `N`
  is the `element_index`. The tree can be very large (Finder is
  ~1600 elements, ~190 KB); when it exceeds token limits the MCP
  harness saves it to a file and returns the path. Use `Bash` +
  `jq -r '.tree_markdown'` + `grep` to pull the section you need.
- `screenshot_file_path` — absolute path to the saved screenshot when
  `screenshot_out_file` was passed. Absent otherwise.
- `screenshot_width` / `_height` / `_scale_factor` — dimensions of the
  captured image. Present whenever a screenshot was taken.
**Getting the screenshot as a file (CLI and context-constrained agents):**

```bash
# write to file — stdout stays readable (AX tree / summary only, no base64)
cua-driver get_window_state '{"pid":N,"window_id":W,"screenshot_out_file":"/tmp/shot.jpg"}'

# CLI --screenshot-out-file flag is equivalent and works for all capture modes
cua-driver get_window_state '{"pid":N,"window_id":W}' --screenshot-out-file /tmp/shot.jpg
```

Pass `screenshot_out_file` when using `get_window_state` via CLI or from an
agent whose context window can't absorb ~31 KB of inline base64 (e.g.
OpenCode with a local Ollama model). The MCP image content block is omitted
from the response when this param is set — the model receives only the AX
tree and `screenshot_file_path`, then reads the image from disk.

**Reason over both the tree AND the screenshot — they're
complementary, not redundant.** In `som` mode every
turn's `get_window_state` gives you both halves and you should pull
signal from each:

- The **AX tree** tells you *what's clickable* — roles, labels,
  `element_index` handles, advertised actions, parent-child
  structure. This is the ground truth for dispatching.
- The **screenshot** tells you *which one* — the tree often has
  many buttons with similar or empty labels ("Delete", "OK",
  anonymous UUID-labeled buttons, five `AXStaticText = " "`), and
  visual context disambiguates. Captions, colors, layout relationships
  visible in pixels often don't show up in the AX tree at all
  (especially in Chromium / Electron / web content).

Canonical pattern: look at the screenshot to decide "the blue
Subscribe button on the top-right of the video card", then walk the
tree to find the matching `AXButton` and dispatch by its
`element_index`. Don't try to do it from just the tree — you'll
pick the wrong element when labels repeat. Don't try to do it from
just the screenshot — you lose the reliable AX-action path and the
safe backgrounded-dispatch.

Reach for pixel coordinates only when the target is a canvas /
video / WebGL / custom-drawn surface that isn't in the AX tree
(see Pixel-coordinate clicks below).

The `actions=[...]` list on each element is **advisory**, not
authoritative. cua-driver does not pre-flight check against it —
`click({pid, element_index})` always attempts `AXPress` (or the
action you pass) and surfaces whatever the target returns. Many
apps accept `AXPress` on elements that don't advertise it — Chrome's
omnibox suggestion `AXMenuItem` is a live example. **Try the click
first** — pivot only on the returned AX error code.

Dispatch table (every row assumes a `(pid, window_id)` pair from the
last `get_window_state`; `window_id` is required alongside
`element_index`, ignored on pixel-only forms unless you want to
anchor the conversion against a specific window):

| Intent | Tool | Notes |
|---|---|---|
| List an app's windows | `list_windows({pid})` | returns `window_id`, `title`, `bounds`, `z_index`, `is_on_screen`, `on_current_space`. Already included in `launch_app`'s response — only call this for long-lived pids |
| Snapshot a window | `get_window_state({pid, window_id})` | returns `tree_markdown` + `screenshot_*`; populates the `(pid, window_id)` element_index cache |
| Left click | `click({pid, window_id, element_index})` | default `action: "press"`. Pixel form: `click({pid, x, y})` (window_id optional — when supplied, pinpoints the anchor window) — `modifier: ["cmd"]` |
| Double-click / open | `double_click({pid, window_id, element_index})` | AXOpen when advertised (Finder items, openable rows); else stamped pixel double-click at the element's center. Pixel form: `double_click({pid, x, y})` — primer-gated recipe lands on backgrounded Chromium web content (YouTube fullscreen, Finder open-on-dbl). `click({..., count: 2})` still works and routes through the same recipe; `double_click` is the intent-first spelling |
| Right click / context menu | `right_click({pid, window_id, element_index})` or `click({pid, window_id, element_index, action: "show_menu"})` | Chromium web-content coerces pixel right-click to left — see `WEB_APPS.md` |
| Type at cursor | `type_text({pid, text, window_id, element_index})` | `AXSelectedText` write; focuses first |
| Set whole field value | `set_value({pid, window_id, element_index, value})` | sliders, steppers, text fields; **use for keyboard-commit workarounds on minimized windows** |
| Scroll | `scroll({pid, direction, amount, by, window_id, element_index})` | synthesizes PageUp/PageDown/arrows via SLEventPostToPid |
| Focus + send key | `press_key({pid, key, window_id, element_index, modifiers})` | element_index sets AXFocused, then posts key |
| Send key to pid | `press_key({pid, key, modifiers})` | no focus change; key goes to pid's current focus |
| Modifier combo | `hotkey({pid, keys})` | e.g. `["cmd","c"]`; posted per-pid, not HID tap |
| Unicode keystrokes | `type_text({pid, text, delay_ms})` | AX write with automatic CGEvent fallback; reaches Chromium/Electron inputs |

**All keyboard/text primitives require `pid`.** There is no
frontmost-routed variant — every key goes to the named target via
`CGEvent.postToPid`, so the driver cannot leak keystrokes into the
user's foreground app.

**Why `element_index` is the primary path:** works on hidden /
occluded / off-Space windows, no focus steal, stable across
rebuilds, labels tell you what you're clicking. Reach for pixel
coordinates only when AX can't.

### Pixel-coordinate clicks

The pixel path (`click({pid, x, y})`) is for surfaces the AX tree
doesn't reach — canvases, video players, WebGL, custom-drawn controls.
Coords are **window-local screenshot pixels** (same space as the PNG
`get_window_state` returns). Top-left origin, y-down. The driver
handles screen-point conversion internally. Passing `window_id`
alongside `x, y` is optional but recommended — it pins the
coordinate conversion to the window whose screenshot produced the
pixel, rather than the driver's heuristic choice.

#### Reading coordinates from the PNG

PNGs returned by `get_window_state` are capped at **1568 px
long-side by default** (`max_image_dimension` config), matching
Anthropic's multimodal-vision downsampling limit. That means the
image the model reasons over and the image the click tool's
coordinate system lives in are the **same resolution** — just look
at the PNG, pick a pixel, click at that pixel. No scaling math.

This is the default because the mismatch between "rendered
thumbnail" and "native PNG" was a recurring coord-estimation
footgun. If you opt out (explicit `max_image_dimension=0` for
pixel-perfect verification flows), the old rule applies: don't
eyeball coords from whatever your client renders — it may be
2-4× smaller than the PNG on disk, and a 2% error in thumbnail
space becomes ~80 px in the real image. Use the crosshair recipe
below against the full-resolution file in that case.

1. `get_window_state({pid, window_id})` returns an image capped
   at 1568 long-side (default) plus its dimensions
   (`screenshot_width` / `screenshot_height`). Write the bytes to
   disk with `--screenshot-out-file <path>` in any capture mode — works
   identically in `vision` (where it's the only way) and `som`
   (where it sidesteps the jq + base64 dance on the spliced
   `screenshot_png_b64` field).
2. You are a multimodal model — look at the PNG. Since the PNG
   matches what you see, pick the target pixel directly. No
   fractional math needed.
3. When precision matters (small targets, dense UIs), draw a
   crosshair on the image (do **not** crop — cropping loses the
   coordinate system and requires error-prone offset math) and
   show it before clicking:

```python
from PIL import Image, ImageDraw
img = Image.open('/tmp/shot.png')
draw = ImageDraw.Draw(img)
x, y = <your_coordinate>
r = 18
draw.ellipse([x-r, y-r, x+r, y+r], outline='red', width=4)
draw.line([x-30, y, x+30, y], fill='red', width=3)
draw.line([x, y-30, x, y+30], fill='red', width=3)
img.save('/tmp/shot_annotated.png')
```

4. Only dispatch the click after the user (or your own re-read of
   the annotated image) confirms the crosshair is on target.

#### Addressing variants

- `click({pid, x, y})` — single left-click.
- `click({pid, x, y, count: 2})` — double-click.
- `click({pid, x, y, modifier: ["cmd"]})` — cmd-click. Accepts any
  subset of `cmd/shift/option/ctrl`.
- `right_click({pid, x, y})` — also takes `modifier`.

The pixel path animates the agent cursor overlay but never warps
the real cursor. If the pid has no on-screen window the call errors
with `pid X has no on-screen window` — you need a visible window to
anchor the conversion.

#### How the pixel click is dispatched

The recipe is the backgrounded "noraise" sequence: yabai's
focus-without-raise SLPS event records followed by an off-screen
user-activation primer and the real click, all stamped via
`SLEventPostToPid`. The target app becomes AppKit-active for event
routing but its window does **not** rise to the front of the
z-stack, and macOS's "switch to Space with windows for app" follow
is suppressed. Full mechanics in
`Sources/CuaDriverCore/Input/MouseInput.swift` (`clickViaAuthSignedPost`)
and the companion `FocusWithoutRaise.swift`.

#### Known limits

- **Chromium `<video>` play/pause**: pixel click is often rejected
  by HTML5's click-to-play handler on some builds. Use keyboard
  instead: `press_key({pid, key: "k"})` (YouTube) or
  `press_key({pid, key: "space"})` (generic). Keyboard events
  travel through a different auth envelope.
- **Pixel right-click on Chromium web content** coerces to a
  left-click — a known Chromium renderer-IPC limitation that affects
  every non-HID-tap synthesis path. For context menus on
  AX-addressable elements (links, buttons, toolbar items), use
  `right_click({pid, element_index})` instead.

### Canvases, viewports, games (Blender, Unity, GHOST, Qt, wxWidgets)

Apps whose main surface is an OpenGL / Metal / Qt / wxWidgets
viewport expose **no useful AX tree** — the whole surface is one
opaque `AXGroup` or `AXWindow` from AX's perspective. Per-pid event
paths (`SLEventPostToPid`, `CGEvent.postToPid`) are filtered by the
viewport's own event-source check and silently dropped — the event
loop wants "real HID origin".

The working pattern:

1. Bring the target frontmost (a brief `osascript activate` is
   acceptable here — this is the carve-out the skill's osascript
   gate allows).
2. `CGEvent.post(tap: .cghidEventTap)` with a leading `mouseMoved`
   event (~30 ms before the click). `cua-driver click` when the
   target is frontmost automatically takes this path.
3. Accept that the real cursor visibly moves — `cghidEventTap` is
   the system HID stream, the cursor warps to the click point.

There is no backgrounded path that reaches these apps today.

## Navigating native menu bars (AXMenuBar)

**Only drive the menu bar when the target app is frontmost.** This
is the single most-misused cua-driver capability. If the target is
backgrounded, don't reach for `AXMenuBarItem` + AXPick — use
in-window `element_index` or pixel clicks instead. Two reasons, one
functional and one perceptual:

- **Functional:** menu items that touch document/playback/editor
  state go `DISABLED` when their owning app isn't the key window
  (Preview rotate, IINA speed change, most editor commands). AXPick
  + AXPress will dispatch successfully from the driver's side but
  no-op at the target — you get a silent false-pass.
- **Perceptual (matters for demos, screen recordings, and anything
  the user watches live):** macOS's screen-rendered menu bar
  always belongs to the *frontmost* app. AXPick on a backgrounded
  app's `AXMenuBarItem` dispatches to that app's per-process menu at
  the AX layer, but any visible menu render happens over the
  frontmost app's menu bar — the viewer sees an IINA submenu
  flashing on top of Chrome's menus, which reads as "the agent
  clicked the wrong app." The AX call was correct; the frame the
  user sees is not. For recorded or observed sessions, this is an
  integrity bug even though it's not a correctness bug.

**Good decision rule:** if the target is not already frontmost, do
not use `AXMenuBarItem` at all. For *reading* in-window state,
snapshot the window AX tree — most apps expose the same state via
an in-window `AXStaticText`, title bar, or toolbar. For *dispatching*
actions, use in-window `element_index` (buttons, toolbar items) or
pixel clicks on in-window controls — both dispatch via AppKit's
window-under-pointer hit-test and are **not** frontmost-gated.

When the target IS frontmost, the menu-bar flow below is fine and
the canonical path for menus.

### The two-snapshot pattern (target frontmost only)

Menu contents are a two-snapshot flow. Closed AXMenu subtrees are
deliberately skipped during snapshot — otherwise every app's File /
Edit / View hierarchy plus every Recent Items macOS has ever seen
would inflate the tree 10-100x. But once a menu is *open*, its
AXMenuItem children do receive `element_index` values so you can
click them normally.

1. Find the `[N] AXMenuBarItem "<Menu Name>"` in the tree.
2. `click({pid, element_index: N, action: "pick"})` — menu bar items
   implement `AXPick` ("open my submenu"), not `AXPress`. Using the
   default action on an AXMenuBarItem is a no-op.
3. Re-snapshot. The expanded menu's items now appear under the bar
   item as `[M] AXMenuItem "<Item Name>"`.
4. Click the target item — most items respond to `AXPress` (default
   action). Submenus nest under the item and are walked the same way.
5. Re-snapshot and verify.

If you ever need to back out without selecting, `press_key({pid, key:
"escape"})` closes the open menu. Leaving a menu expanded between
turns poisons subsequent snapshots for that pid.

### Commands gated on the target being frontmost

Some menu items and global shortcuts (Preview's Tools → Rotate
Right, ⌘R; anything in the View menu that manipulates the current
document; most editor commands) are **disabled unless the target
app is the key / frontmost window**. You'll see it in the AX tree
as `DISABLED` on the menu item even though the user's intent is
obviously valid.

Before activating, confirm you're in this narrow case — the menu
item still reads `DISABLED` after a fresh snapshot AND the action
the user requested genuinely requires frontmost (Preview rotate,
View menu document manipulation, editor commands). If either
check fails, don't activate.

When both checks pass, the driver has no `activate` tool
(deliberately — the whole point is backgroundable control), so
this is the one legitimate `osascript` fallback:

```
osascript -e 'tell application "<App Name>" to activate'
```

Then re-snapshot — the menu item loses its `DISABLED` tag — and
`click({action: "pick"})` the item. Alternatively, a `hotkey`
call delivered to the now-frontmost app works for the shortcut
form (`⌘R`, `⌘+`, etc.).

**Always name the focus steal in your response** so the user isn't
surprised — "Briefly activating Preview to enable Tools → Rotate
Right" or similar. Don't silently steal focus. You don't need to
restore the previous frontmost afterwards unless the user asks —
they can cmd-tab back.

## Web-rendered apps (browsers, Electron, Tauri)

For Chrome / Edge / Brave / Arc / Safari, Electron apps (Slack,
VSCode, Notion, Discord), and Tauri apps — see **`WEB_APPS.md`**.

Covers: sparse AX tree population (retry-once pattern for Chromium),
URL navigation via omnibox suggestions, the `set_value` workaround
for keyboard commits on **minimized** windows (Return silently
no-ops — symptom is a macOS system beep; use `set_value` or click a
clickable equivalent), scrolling via synthetic PageUp/Down keystrokes,
in-page clicks, and typing into web inputs.

Chromium web content specifically also coerces `right_click` back to
left — use `element_index` for AX-addressable targets and accept the
limit otherwise.

### Browser JS primitives — `page` tool and `get_window_state(javascript=)`

When the AX tree doesn't expose the data you need (common in
Chromium/Electron — the tree is sparse for web content), use the
`page` tool or the `javascript` param on `get_window_state` to query
the DOM directly via Apple Events. Requires "Allow JavaScript from
Apple Events" to be enabled — see `WEB_APPS.md` for the setup path.

**Three actions on the `page` tool:**

- `page({pid, window_id, action: "get_text"})` — returns
  `document.body.innerText`. Fastest way to read page content, prices,
  article text, or any raw text the AX tree truncates or omits.

- `page({pid, window_id, action: "query_dom", css_selector: "a[href]",
  attributes: ["href"]})` — runs `querySelectorAll` and returns each
  match's tag, text, and requested attributes as a JSON array. Use for
  table rows, link hrefs, data attributes, structured page data.

- `page({pid, window_id, action: "execute_javascript", javascript:
  "..."})` — raw JS. Wrap in an IIFE with try-catch. Don't use this for
  elements already indexed by `get_window_state` — `click` and
  `set_value` are more reliable there.

**Co-located read — `get_window_state` with `javascript`:**

```
get_window_state({pid, window_id, javascript: "document.title"})
```

Runs the JS and appends the result as a `## JavaScript result` section
alongside the AX snapshot — one round-trip instead of two. Use this
when you need both the element tree (for subsequent clicks) and some
page data in the same turn.

**Decision rule — AX vs JS:**

| Need | Use |
|---|---|
| Click / type into an element | `get_window_state` → `click` / `set_value` (AX, works backgrounded) |
| Read text the AX tree drops | `page(get_text)` or `get_window_state(javascript=)` |
| Scrape structured data (tables, hrefs) | `page(query_dom)` |
| Trigger JS events / mutations | `page(execute_javascript)` |

Supported backends:

| App type | How | Context |
|---|---|---|
| Chrome / Brave / Edge | Apple Events `execute javascript` | Full DOM ✅ |
| Safari | Apple Events `do JavaScript` | Full DOM ✅ |
| Electron (VS Code, Cursor…) | SIGUSR1 → V8 inspector → CDP | Main process only: `process`, `Buffer` — no `document`, no `require` in sandboxed apps |
| Electron (with `--remote-debugging-port`) | CDP page target | Full DOM ✅ |

**Electron sandbox note:** SIGUSR1 connects to the Node.js *main* process.
Sandboxed Electron apps (VS Code, Cursor) strip `require` and Electron
APIs there. Useful for: `process.env`, `process.versions`, `process.cwd()`,
`process.pid`. For full DOM/renderer access, launch the app with
`--remote-debugging-port=9222` — cua-driver will detect and prefer the
page target automatically.

Arc returns no values; Firefox has no JS-via-AppleEvents support — see
`WEB_APPS.md` for the full matrix.

### 3. Re-snapshot and verify — mandatory

**Always** call `get_window_state({pid, window_id})` after the action.
This isn't optional verification — it's the second half of the
snapshot invariant.

Check the AX tree diff: a changed value, a new element, a new
window, or the disappearance of the thing you just clicked (menus
collapse after selection, buttons may become disabled, etc.). If
nothing changed, the action likely failed silently — **tell the
user what you attempted and what you observed**, don't paper over
with "done" language. Agents that skip this step report success on
silently-dropped actions — the single most common failure mode.

## Recording trajectories

Session-scoped action recording + replay, for demos, regressions, and
training data. Only invoke when the user explicitly asks to record a
session — the skill does not auto-enable this. CLI surface:
`cua-driver recording start|stop|status`; raw tool: `set_recording`.

See **`RECORDING.md`** for the full flow: enable/disable, turn folder
contents, replay via `replay_trajectory`, and the element_index
doesn't-survive-across-sessions caveat.

## Common error patterns

| Error text | Meaning | Fix |
|---|---|---|
| `No cached AX state for pid X window_id W` | You either skipped `get_window_state` this turn, or passed a different `window_id` to the click than the one the snapshot cached against | Call `get_window_state({pid: X, window_id: W})` first — the same window_id you intend to click in |
| `Invalid element_index N for pid X window_id W` | Index is stale or out of range | Re-run `get_window_state` with the same window_id, pick a fresh index from the new tree |
| `window_id W belongs to pid P, not …` | Passed a window_id that's owned by a different process | Use `list_windows({pid: X})` to enumerate this pid's own windows |
| `AX action AXPress failed with code …` | Element doesn't support AXPress | Try `show_menu`, `confirm`, `cancel`, or `pick` |
| macOS system-alert beep on `press_key` with no visible change | Target window is minimized; Return / Space / Tab commits don't establish real renderer focus on minimized windows | AX-click a clickable equivalent (Go button, Submit button, checkbox) instead of pressing the key; see "Keyboard commits on minimized windows" under the Browser section |
| `Accessibility permission not granted` | TCC not granted | Stop; tell user to grant in System Settings |
| `Screen Recording permission not granted` | TCC not granted for capture | Affects `screenshot` and `get_window_state` (which always captures). Grant in System Settings — the driver can't operate without it |

## Things to avoid

- **Never** reuse an `element_index` across a re-snapshot of the same pid.
- **Never** translate screenshot pixels into a click — the screenshot
  is for visual disambiguation, not coordinates. Use the
  `element_index`.
- **Prefer AX over pixels.** `click({pid, x, y})` works for
  canvas / WebView regions, but it lands blindly and skips the
  agent-cursor overlay. Exhaust AX paths (menu bars, cmd-k palettes,
  toolbar items, keyboard shortcuts) before dropping to coordinates.
- **Never** drive destructive actions (delete files, close unsaved
  documents, send messages, submit forms) without explicit user
  intent for that specific destructive step.
- **Never** launch apps autonomously; confirm with the user first
  unless their original request clearly implies the launch.

## Example end-to-end task

**User:** "Open the Downloads folder in Finder."

1. `launch_app({bundle_id: "com.apple.finder", urls: ["~/Downloads"]})`
   → `{pid: 844, windows: [{window_id: 6123, title: "Downloads", ...}]}`.
   Idempotent launch; plus Finder opens a hidden window rooted at
   `~/Downloads` via `application(_:open:)` — zero activation, no
   focus steal. The `windows` array lets you skip a `list_windows` hop.
2. `get_window_state({pid: 844, window_id: 6123})` → verify an
   `AXWindow` whose title contains "Downloads" is present with a
   populated AX subtree (sidebar, list view, files).
3. Done.

If the user instead asks to navigate *within* an already-open Finder
window, use the menu-bar flow from the "Navigating native menu bars"
section above (click Go → pick a menu item → re-snapshot → click it).
