feat(driver): add EraseText to the device driver surface

internal/driver/chrome/driver.go

@@ -193,6 +193,23 @@ func (d *Driver) InputText(_ context.Context, text string) error {
 	)
 }
 
+// EraseText clears the focused field. InputText above already replaces via
+// select-all, so the character count is not needed to bound the deletion.
+func (d *Driver) EraseText(_ context.Context, _ int) error {
+	return chromedp.Run(d.tabCtx,
+		chromedp.ActionFunc(func(ctx context.Context) error {
+			if err := chromedp.Evaluate(`
+				(function() {
+					const el = document.activeElement;
+					if (el && typeof el.select === 'function') el.select();
+				})()`, nil).Do(ctx); err != nil {
+				return err
+			}
+			return input.InsertText("").Do(ctx)
+		}),
+	)
+}
+
 func (d *Driver) Swipe(_ context.Context, fromX, fromY, toX, toY int, duration time.Duration) error {
 	millis := max(duration.Milliseconds(), 50)
 	script := fmt.Sprintf(`

internal/driver/driver.go

@@ -20,6 +20,10 @@ type DeviceDriver interface {
 	DoubleTap(ctx context.Context, x, y int) error
 	DoubleTapSelector(ctx context.Context, selector string) error
 	InputText(ctx context.Context, text string) error
+	// EraseText deletes characterCount characters from the focused field.
+	// The runner calls it before InputText so the verb replaces existing
+	// content instead of appending to it.
+	EraseText(ctx context.Context, characterCount int) error
 	Swipe(ctx context.Context, fromX, fromY, toX, toY int, duration time.Duration) error
 	PressKey(ctx context.Context, key string) error
 	LongPress(ctx context.Context, x, y int) error

internal/driver/mock/mock.go

@@ -19,6 +19,7 @@ const (
 	ActionDoubleTap         ActionKind = "double_tap"
 	ActionDoubleTapSelector ActionKind = "double_tap_selector"
 	ActionInputText         ActionKind = "input_text"
+	ActionEraseText         ActionKind = "erase_text"
 	ActionSwipe             ActionKind = "swipe"
 	ActionPressKey          ActionKind = "press_key"
 	ActionLongPress         ActionKind = "long_press"
@@ -32,19 +33,20 @@ const (
 )
 
 type Action struct {
-	Kind         ActionKind
+	Kind           ActionKind
-	BundleID     string
+	BundleID       string
-	ClearState   bool
+	ClearState     bool
-	X, Y         int
+	X, Y           int
-	FromX, FromY int
+	FromX, FromY   int
-	ToX, ToY     int
+	ToX, ToY       int
-	Duration     time.Duration
+	Duration       time.Duration
-	Selector     string
+	Selector       string
-	Text         string
+	Text           string
-	Key          string
+	CharacterCount int
-	LogLevel     string
+	Key            string
-	LogSince     time.Time
+	LogLevel       string
-	Idle         time.Duration
+	LogSince       time.Time
+	Idle           time.Duration
 }
 
 // Driver is an in-memory Driver implementation for unit tests.
@@ -210,6 +212,14 @@ func (d *Driver) InputText(ctx context.Context, text string) error {
 	return nil
 }
 
+func (d *Driver) EraseText(ctx context.Context, characterCount int) error {
+	if err := d.failure(ActionEraseText); err != nil {
+		return err
+	}
+	d.record(Action{Kind: ActionEraseText, CharacterCount: characterCount})
+	return nil
+}
+
 func (d *Driver) Swipe(ctx context.Context, fromX, fromY, toX, toY int, duration time.Duration) error {
 	if err := d.failure(ActionSwipe); err != nil {
 		return err

internal/driver/sidecar/client.go

@@ -137,6 +137,11 @@ func (c *Client) InputText(ctx context.Context, text string) error {
 	return err
 }
 
+func (c *Client) EraseText(ctx context.Context, characterCount int) error {
+	_, err := c.stub.EraseText(ctx, &driverpb.EraseTextRequest{CharacterCount: int32(characterCount)})
+	return err
+}
+
 func (c *Client) Swipe(ctx context.Context, fromX, fromY, toX, toY int, duration time.Duration) error {
 	_, err := c.stub.Swipe(ctx, &driverpb.SwipeRequest{
 		From:           &driverpb.Point{X: int32(fromX), Y: int32(fromY)},