Focus

Snapshot the Compose focus state of a preview and drive directional focus traversal (Up, Down, Left, Right, Next, Previous) so agents can verify keyboard / D-pad navigation without an emulator.

At a glance


Kind	`compose/focus`
Schema version	1
Modules	`:data-focus-core` (published) · `:data-focus-connector`
Render mode	default
Cost	low
Token usage	Inline JSON, not yet benchmarked. See token usage.
Transport	inline
Platforms	Android · Desktop · Wear · shared

What it answers

Which node holds focus right now? What testTag, role, label?
After a directional moveFocus(FocusDirection.Down), where does focus land?
Is there a focus trap, dead end, or unexpected wrap?
Does the focus ring overlay match the focusable bounds the developer expects?

The connector ships a FocusController that drives Compose’s FocusManager and a FocusOverlay that renders the focused-node bounding box on top of the captured PNG.

What it does NOT answer

It does not test physical input devices (rotary, gamepad, IME hardware) — it operates on the abstract FocusDirection enum.
It does not score focus order against a designer-defined intent — it reports what the framework chose; reading whether that’s right is on the reviewer.

Use cases

TV / Wear traversal: render every Up/Down/Left/Right step from a known starting node and confirm the path lands on the intended target.
Dialog focus restoration: verify focus comes back to the trigger button after a dialog dismisses.
Form regression: catch a refactor that accidentally makes a TextField non-focusable.

Override shape

Material3FocusProduct.KIND / FocusOverride and FocusDirection in :data-focus-core and daemon:core.

compose/focus is an override capability, not a focused-node snapshot payload. A renderNow request carries the focus instruction under overrides.focus:

{
  "overrides": {
    "focus": {
      "tabIndex": 1,
      "direction": "Down",
      "step": 1,
      "overlay": true,
      "pressed": false
    }
  }
}

Use compose/semantics to identify the resulting focused node and its boundsInRoot.

Enabling

Pass an override on renderNow.overrides.focus (MCP) to drive traversal, or enable the extension and read focused-node snapshots on every render.

Companion products

UIAutomator hierarchy — uia/hierarchy for the broader set of selector-shaped nodes a click / scroll / type could target.
Layout inspector — compose/semantics for testTag / role / mergeMode of the focused node.