# Interaction Cookbook

Copy-paste recipes for driving a running Flutter app from an agent using the
Playwright-style interaction layer. Every example assumes:

```bash
WS='ws://127.0.0.1:8181/<token>/ws'   # from `discover_debug_apps`
CLI='flutter-mcp-toolkit'              # the built CLI binary
```

All interaction tools run against the shared command catalog and take the
usual nested `connection` object for targeting.

## 1. Tap a button

```bash
# 1. Snapshot → get refs for every interactive widget on screen.
$CLI exec --name semantic_snapshot \
  --args "{\"connection\":{\"targetId\":\"$WS\"}}"

# 2. Tap the ref you want. Pass snapshotId to detect staleness.
$CLI exec --name tap_widget \
  --args "{\"ref\":\"s_1\",\"snapshotId\":4,\"connection\":{\"targetId\":\"$WS\"}}"
```

The response includes `via: "semantic_action"` when Tier 1 succeeded
(`SemanticsOwner.performAction`) or `via: "pointer_events"` when it fell back
to synthetic taps.

## 2. Fill a form field

```bash
# ref comes from a previous semantic_snapshot call.
$CLI exec --name enter_text \
  --args "{\"ref\":\"s_3\",\"text\":\"hello\",\"connection\":{\"targetId\":\"$WS\"}}"
```

`enter_text` prefers `SemanticsAction.setText` and falls back to driving
`EditableTextState.userUpdateTextEditingValue` directly. `TextInputFormatter`s
and `onChanged` fire correctly.

## 3. Scroll to reveal more content

```bash
# Pass a scrollable ref for the deterministic semantic-action path.
$CLI exec --name scroll \
  --args "{\"ref\":\"s_6\",\"direction\":\"down\",\"connection\":{\"targetId\":\"$WS\"}}"

# Without a ref, scroll dispatches a PointerScrollEvent at screen centre
# (desktop-friendly wheel path).
$CLI exec --name scroll \
  --args "{\"direction\":\"down\",\"distance\":400,\"connection\":{\"targetId\":\"$WS\"}}"

# Re-snapshot — off-screen widgets are only in the tree after they scroll in.
$CLI exec --name semantic_snapshot \
  --args "{\"connection\":{\"targetId\":\"$WS\"}}"
```

Direction follows the Playwright convention: `direction: "down"` reveals
content below (the finger swipes up).

## 4. Read runtime state without registering a tool

```bash
$CLI exec --name evaluate_dart_expression \
  --args "{\"expression\":\"AgentState.instance.counter\",\"connection\":{\"targetId\":\"$WS\"}}"
```

Evaluates in the app's root library and returns `{result, kind, classRef}`.
Useful for asserting "did the tap I just issued actually update state?"
without waiting for a visual diff.

## 5. Edit → hot reload → see what changed

```bash
# After editing a Dart file:
$CLI exec --name hot_reload_and_capture \
  --args "{\"connection\":{\"targetId\":\"$WS\"}}"
```

Returns a single response with `hotReload` report, fresh `screenshot`, fresh
`semantics` (new `snapshot_id`), and any app `errors` raised during reassembly.
One round trip replaces the classic "reload, then snapshot, then errors" chain.

## Staleness handshake

Every interaction tool accepts an optional `snapshotId`. If it doesn't match
the server's current snapshot the call returns:

```json
{
  "ok": false,
  "error": "stale_snapshot",
  "providedSnapshotId": 4,
  "currentSnapshotId": 7,
  "message": "Snapshot is stale. Call semantic_snapshot to get fresh refs."
}
```

Handle by re-issuing `semantic_snapshot`, remapping refs, then retrying.

## Known limits (quick reference)

- Refs only resolve against the most recent snapshot.
- Off-screen widgets aren't in the snapshot until they scroll into view.
- Scroll by `ref` is the most reliable path — no-ref scroll uses a
  `PointerScrollEvent` that a full-screen overlay can swallow.
- Widgets without `Semantics` are invisible to the snapshot; reach them via
  `inspect_widget_at_point` + Tier 2 pointer events.
- Platform views / custom text input can't be filled through
  `userUpdateTextEditingValue`; use `evaluate_dart_expression` to set state
  directly.

See [CLI quick recipes](/start_here/cli_quick_recipes) for copy-paste coverage of the shared command catalog.
