Merge branch 'master' into fix-violation-step-attribution

examples/folio/sanderling/spec.ts

@@ -10,7 +10,7 @@ import {
   weighted,
   whenRoute,
 } from "@sanderling/spec";
-import { defaultActions } from "@sanderling/spec/defaults";
+import { defaultActions, doubleTaps } from "@sanderling/spec/defaults";
 import {
   computeHomeTotalBalance,
   parseTypedAmount,
@@ -174,11 +174,16 @@ export const properties = {
 
 export const setup = login;
 
-// Targeted depth (addAccount / addTxn) drives the deep flows; defaultActions
+// Weights declare testing intent. The transaction chain is the focus: it is
-// adds breadth so the fuzzer wanders the whole app and types edge-case values
+// the deepest flow and both balance properties observe it. Account creation
-// into every field, stressing the balance invariants above.
+// stays in the mix because newAccountBalanceIsZero needs fresh accounts to
+// fire. doubleTaps gets explicit weight on every screen because rapid
+// double-submission is a failure mode these forms must be idempotent under.
+// defaultActions adds breadth so the fuzzer wanders the whole app and types
+// edge-case values into every field.
 export const actionsRoot = weighted(
-  [50, addAccount],
+  [25, addAccount],
-  [30, addTxn],
+  [45, addTxn],
-  [20, defaultActions],
+  [5, doubleTaps],
+  [25, defaultActions],
 );

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

@@ -104,14 +104,18 @@ func (c *Client) TapSelector(ctx context.Context, selector string) error {
 	return err
 }
 
-// doubleTapGap is the inter-tap delay for DoubleTap: short enough to land both
+// doubleTapGap is the inter-tap delay for the selector fallback: short enough
-// events inside a sub-100 ms race window, long enough for the sidecar to
+// to land both events inside a sub-100 ms race window, long enough for the
-// serialize two MotionEvent streams. The sidecar exposes no native double-tap
+// sidecar to serialize two MotionEvent streams.
-// RPC, so the gesture is two Taps with this gap.
 const doubleTapGap = 50 * time.Millisecond
 
+// DoubleTap dispatches the native RPC so the backend can land both taps as
+// close together as the platform allows. Composing two Tap round trips from
+// here spreads them by hundreds of milliseconds on iOS, wide enough for
+// navigation to interleave between the taps.
 func (c *Client) DoubleTap(ctx context.Context, x, y int) error {
-	return doubleTap(ctx, func() error { return c.Tap(ctx, x, y) })
+	_, err := c.stub.DoubleTap(ctx, &driverpb.Point{X: int32(x), Y: int32(y)})
+	return err
 }
 
 func (c *Client) DoubleTapSelector(ctx context.Context, selector string) error {
@@ -137,6 +141,11 @@ 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)},

internal/hierarchy/hierarchy.go

@@ -75,6 +75,7 @@ type Element struct {
 type Node struct {
 	Element
 	Children []*Node `json:"-"`
+	tree     *Tree
 }
 
 // Tree is a flat collection of every node in a hierarchy dump, in pre-order.
@@ -180,7 +181,7 @@ func Parse(text string) (*Tree, error) {
 }
 
 func walkNode(node *treeNodeJSON, tree *Tree) *Node {
-	n := &Node{Element: *elementFromNode(node)}
+	n := &Node{Element: *elementFromNode(node), tree: tree}
 	tree.Elements = append(tree.Elements, &n.Element)
 	for i := range node.Children {
 		n.Children = append(n.Children, walkNode(&node.Children[i], tree))
@@ -333,69 +334,50 @@ func (t *Tree) FindAllBySelectorPath(path []Selector) []*Node {
 	return t.Root.FindAllBySelectorPath(path)
 }
 
-// Find returns the first Node in this node's subtree (descendants only) matching
+// Find returns the first Node scoped to this node (descendants, with spatial
-// the string selector. Path queries within the selector are not supported here.
+// fallback) matching the string selector. Path queries within the selector are
+// not supported here.
 func (n *Node) Find(selector string) *Node {
-	kind, value, ok := parseSelector(selector)
+	return firstNode(n.FindAll(selector))
-	if !ok {
-		return nil
-	}
-	for _, child := range n.Children {
-		if nodes := searchSubtree(child, kind, value); len(nodes) > 0 {
-			return nodes[0]
-		}
-	}
-	return nil
 }
 
-// FindAll returns all Nodes in this node's subtree (descendants only) matching
+// FindAll returns all Nodes scoped to this node (descendants, with spatial
-// the string selector.
+// fallback) matching the string selector.
 func (n *Node) FindAll(selector string) []*Node {
 	kind, value, ok := parseSelector(selector)
 	if !ok {
 		return nil
 	}
-	var result []*Node
+	return n.scopedNodes(func(element *Element) bool {
-	for _, child := range n.Children {
+		return match(element, kind, value)
-		result = append(result, searchSubtree(child, kind, value)...)
+	})
-	}
-	return result
 }
 
-// FindBySelector returns the first Node in this node's subtree matching sel (AND semantics).
+// FindBySelector returns the first Node scoped to this node matching sel (AND semantics).
 func (n *Node) FindBySelector(sel Selector) *Node {
-	for _, child := range n.Children {
+	return firstNode(n.FindAllBySelector(sel))
-		if nodes := searchSubtreeBySelector(child, sel); len(nodes) > 0 {
-			return nodes[0]
-		}
-	}
-	return nil
 }
 
-// FindAllBySelector returns all Nodes in this node's subtree matching sel (AND semantics).
+// FindAllBySelector returns all Nodes scoped to this node matching sel (AND semantics).
 func (n *Node) FindAllBySelector(sel Selector) []*Node {
-	var result []*Node
+	return n.scopedNodes(func(element *Element) bool {
-	for _, child := range n.Children {
+		return matchSelector(element, sel)
-		result = append(result, searchSubtreeBySelector(child, sel)...)
+	})
-	}
-	return result
 }
 
 // FindBySelectorPath walks a chain of selectors. The first selector is matched
-// against descendants of the receiver; each subsequent selector is matched
+// in the receiver's scope; each subsequent selector is matched in the scope of
-// against descendants of the previous match. Returns the deepest match or nil.
+// the previous match. Returns the deepest match or nil.
 func (n *Node) FindBySelectorPath(path []Selector) *Node {
 	if len(path) == 0 {
 		return nil
 	}
-	for _, child := range n.Children {
+	for _, candidate := range n.FindAllBySelector(path[0]) {
-		for _, candidate := range searchSubtreeBySelector(child, path[0]) {
+		if len(path) == 1 {
-			if len(path) == 1 {
+			return candidate
-				return candidate
+		}
-			}
+		if deeper := candidate.FindBySelectorPath(path[1:]); deeper != nil {
-			if deeper := candidate.FindBySelectorPath(path[1:]); deeper != nil {
+			return deeper
-				return deeper
-			}
 		}
 	}
 	return nil
@@ -407,19 +389,86 @@ func (n *Node) FindAllBySelectorPath(path []Selector) []*Node {
 	if len(path) == 0 {
 		return nil
 	}
+	var result []*Node
+	for _, candidate := range n.FindAllBySelector(path[0]) {
+		if len(path) == 1 {
+			result = append(result, candidate)
+			continue
+		}
+		result = append(result, candidate.FindAllBySelectorPath(path[1:])...)
+	}
+	return result
+}
+
+func firstNode(nodes []*Node) *Node {
+	if len(nodes) == 0 {
+		return nil
+	}
+	return nodes[0]
+}
+
+// scopedNodes returns this node's descendants matching accept, in pre-order.
+// When no descendant matches, nodes spatially contained in this node's bounds
+// are matched instead. Compose on iOS emits a testTag node as an empty leaf
+// sibling of the content it labels rather than as an ancestor, so descendant
+// search under the tagged node finds nothing; bounds containment recovers the
+// intended scope.
+func (n *Node) scopedNodes(accept func(*Element) bool) []*Node {
 	var result []*Node
 	for _, child := range n.Children {
-		for _, candidate := range searchSubtreeBySelector(child, path[0]) {
+		collectMatches(child, accept, &result)
-			if len(path) == 1 {
+	}
-				result = append(result, candidate)
+	if len(result) > 0 {
-				continue
+		return result
-			}
+	}
-			result = append(result, candidate.FindAllBySelectorPath(path[1:])...)
+	for _, candidate := range n.spatialScope() {
+		if accept(&candidate.Element) {
+			result = append(result, candidate)
 		}
 	}
 	return result
 }
 
+func collectMatches(node *Node, accept func(*Element) bool, result *[]*Node) {
+	if accept(&node.Element) {
+		*result = append(*result, node)
+	}
+	for _, child := range node.Children {
+		collectMatches(child, accept, result)
+	}
+}
+
+// spatialScope returns every node in the tree, in pre-order, whose positive
+// bounds lie fully inside this node's bounds, excluding the node itself.
+func (n *Node) spatialScope() []*Node {
+	if n.tree == nil || n.tree.Root == nil {
+		return nil
+	}
+	if n.Bounds.Width() <= 0 || n.Bounds.Height() <= 0 {
+		return nil
+	}
+	var result []*Node
+	var walk func(*Node)
+	walk = func(candidate *Node) {
+		if candidate != n &&
+			candidate.Bounds.Width() > 0 && candidate.Bounds.Height() > 0 &&
+			containsBounds(n.Bounds, candidate.Bounds) {
+			result = append(result, candidate)
+		}
+		for _, child := range candidate.Children {
+			walk(child)
+		}
+	}
+	walk(n.tree.Root)
+	return result
+}
+
+// containsBounds reports whether outer fully contains inner (inclusive).
+func containsBounds(outer, inner Bounds) bool {
+	return inner.Left >= outer.Left && inner.Top >= outer.Top &&
+		inner.Right <= outer.Right && inner.Bottom <= outer.Bottom
+}
+
 func findPathNode(root *Node, segments []string) *Node {
 	if root == nil || len(segments) == 0 {
 		return nil
@@ -440,18 +489,12 @@ func findPathNode(root *Node, segments []string) *Node {
 }
 
 func findPathDescendantsNode(root *Node, segments []string) *Node {
-	kind, value, ok := parseSelector(segments[0])
+	for _, node := range root.FindAll(segments[0]) {
-	if !ok {
+		if len(segments) == 1 {
-		return nil
+			return node
-	}
+		}
-	for _, child := range root.Children {
+		if result := findPathDescendantsNode(node, segments[1:]); result != nil {
-		for _, node := range searchSubtree(child, kind, value) {
+			return result
-			if len(segments) == 1 {
-				return node
-			}
-			if result := findPathDescendantsNode(node, segments[1:]); result != nil {
-				return result
-			}
 		}
 	}
 	return nil
@@ -477,19 +520,13 @@ func findPathAllNodes(root *Node, segments []string) []*Node {
 }
 
 func findPathAllDescendantsNodes(root *Node, segments []string) []*Node {
-	kind, value, ok := parseSelector(segments[0])
-	if !ok {
-		return nil
-	}
 	var result []*Node
-	for _, child := range root.Children {
+	for _, node := range root.FindAll(segments[0]) {
-		for _, node := range searchSubtree(child, kind, value) {
+		if len(segments) == 1 {
-			if len(segments) == 1 {
+			result = append(result, node)
-				result = append(result, node)
+			continue
-				continue
-			}
-			result = append(result, findPathAllDescendantsNodes(node, segments[1:])...)
 		}
+		result = append(result, findPathAllDescendantsNodes(node, segments[1:])...)
 	}
 	return result
 }

internal/hierarchy/hierarchy_test.go

@@ -730,3 +730,145 @@ func TestExplicitPackageAttributeWins(t *testing.T) {
 		t.Errorf("package = %q, want app.folio (explicit attr should win)", got)
 	}
 }
+
+// iosFlatDump mirrors the Compose-on-iOS accessibility shape: the testTag node
+// surfaces as an empty leaf SIBLING of the container holding the content it
+// labels, with equal bounds, instead of as an ancestor.
+const iosFlatDump = `{
+  "attributes": {"bounds": "[0,0][402,874]"},
+  "children": [
+    {
+      "attributes": {"accessibilityText": "Folio", "bounds": "[0,0][402,874]"},
+      "children": [
+        {
+          "attributes": {"resource-id": "LoginScreen", "bounds": "[0,62][402,840]"},
+          "children": []
+        },
+        {
+          "attributes": {"bounds": "[0,62][402,840]"},
+          "children": [
+            {
+              "attributes": {"accessibilityText": "EMAIL", "bounds": "[20,106][60,120]"},
+              "children": []
+            },
+            {
+              "attributes": {"resource-id": "LoginEmail", "accessibilityText": "Email", "bounds": "[34,125][368,173]"},
+              "children": [
+                {"attributes": {"bounds": "[34,125][368,173]"}, "children": []}
+              ]
+            },
+            {
+              "attributes": {"resource-id": "LoginPassword", "accessibilityText": "Password", "bounds": "[34,205][368,253]"},
+              "children": []
+            },
+            {
+              "attributes": {"text": "Sign in", "bounds": "[20,297][382,345]"},
+              "children": []
+            },
+            {
+              "attributes": {"resource-id": "LoginSubmit", "accessibilityText": "Sign in", "bounds": "[20,297][382,345]"},
+              "children": [
+                {"attributes": {"text": "Sign in", "resource-id": "SubmitLabel", "bounds": "[168,312][233,330]"}, "children": []}
+              ]
+            }
+          ]
+        }
+      ]
+    },
+    {
+      "attributes": {"bounds": "[0,0][402,54]"},
+      "children": [
+        {
+          "attributes": {"resource-id": "StatusClock", "accessibilityText": "3:24 PM", "bounds": "[55,22][92,42]"},
+          "children": []
+        }
+      ]
+    }
+  ]
+}`
+
+func TestIOSFlatSelectorPathFallsBackToBounds(t *testing.T) {
+	tree, err := Parse(iosFlatDump)
+	if err != nil {
+		t.Fatalf("Parse: %v", err)
+	}
+	path := []Selector{
+		{Filters: []AttrFilter{{Attr: "testTag", Value: "LoginScreen"}}},
+		{Filters: []AttrFilter{{Attr: "testTag", Value: "LoginEmail"}}},
+	}
+	node := tree.FindBySelectorPath(path)
+	if node == nil {
+		t.Fatal("expected LoginEmail via bounds containment under leaf LoginScreen")
+	}
+	if node.ResourceID != "LoginEmail" {
+		t.Fatalf("got %q, want LoginEmail", node.ResourceID)
+	}
+}
+
+func TestIOSFlatStringPathFallsBackToBounds(t *testing.T) {
+	tree, _ := Parse(iosFlatDump)
+	element := tree.Find("id:LoginScreen > id:LoginSubmit")
+	if element == nil {
+		t.Fatal("expected LoginSubmit via bounds containment under leaf LoginScreen")
+	}
+	if element.ResourceID != "LoginSubmit" {
+		t.Fatalf("got %q, want LoginSubmit", element.ResourceID)
+	}
+}
+
+func TestIOSFlatScopedNodeFindFallsBackToBounds(t *testing.T) {
+	tree, _ := Parse(iosFlatDump)
+	screen := tree.FindNode("id:LoginScreen")
+	if screen == nil {
+		t.Fatal("expected LoginScreen node")
+	}
+	node := screen.Find("id:LoginPassword")
+	if node == nil {
+		t.Fatal("expected LoginPassword via bounds containment")
+	}
+	if node.ResourceID != "LoginPassword" {
+		t.Fatalf("got %q, want LoginPassword", node.ResourceID)
+	}
+}
+
+func TestIOSFlatFindAllBySelectorPathReturnsEachField(t *testing.T) {
+	tree, _ := Parse(iosFlatDump)
+	path := []Selector{
+		{Filters: []AttrFilter{{Attr: "testTag", Value: "LoginScreen"}}},
+		{Filters: []AttrFilter{{Attr: "label", Value: "word"}}},
+	}
+	// label "word" substring-matches "Password" only.
+	nodes := tree.FindAllBySelectorPath(path)
+	if len(nodes) != 1 {
+		t.Fatalf("got %d nodes, want 1", len(nodes))
+	}
+	if nodes[0].ResourceID != "LoginPassword" {
+		t.Fatalf("got %q, want LoginPassword", nodes[0].ResourceID)
+	}
+}
+
+func TestIOSFlatSpatialScopeExcludesOutsideBounds(t *testing.T) {
+	tree, _ := Parse(iosFlatDump)
+	// StatusClock sits in the status bar above LoginScreen's bounds; the
+	// spatial fallback must not leak it into the screen's scope.
+	if tree.Find("id:LoginScreen > id:StatusClock") != nil {
+		t.Fatal("StatusClock is outside LoginScreen bounds, expected nil")
+	}
+}
+
+func TestIOSFlatStructuralChildStillPreferred(t *testing.T) {
+	tree, _ := Parse(iosFlatDump)
+	submit := tree.FindNode("id:LoginSubmit")
+	if submit == nil {
+		t.Fatal("expected LoginSubmit node")
+	}
+	// "Sign in" exists as the structural child of LoginSubmit and as an
+	// equal-bounds sibling decoration; the structural child must win.
+	node := submit.Find("text:Sign in")
+	if node == nil {
+		t.Fatal("expected structural child match")
+	}
+	if node.ResourceID != "SubmitLabel" {
+		t.Fatalf("expected the structural child SubmitLabel, got id=%q", node.ResourceID)
+	}
+}

internal/runner/runner.go

@@ -497,6 +497,15 @@ func applyAction(ctx context.Context, drv driver.DeviceDriver, action verifier.A
 				return err
 			}
 		}
+		// InputText replaces the field's content: erase what the target
+		// holds before typing. Appending instead lets repeated draws grow
+		// the field without bound (e.g. into a max-length validation error
+		// the fuzzer can never escape) and makes retried typing land twice.
+		if count := existingTextLength(action, tree); count > 0 {
+			if err := drv.EraseText(ctx, count); err != nil {
+				return err
+			}
+		}
 		return drv.InputText(ctx, action.Text)
 	case verifier.ActionKindSwipe:
 		duration := time.Duration(action.DurationMillis) * time.Millisecond
@@ -547,6 +556,20 @@ func collectLogs(ctx context.Context, drv driver.DeviceDriver, since time.Time)
 	return result
 }
 
+// existingTextLength returns the character count of the InputText target's
+// current text, so the runner can erase it before typing. Zero when the
+// target cannot be resolved or holds no text.
+func existingTextLength(action verifier.Action, tree *hierarchy.Tree) int {
+	if action.On == "" || tree == nil {
+		return 0
+	}
+	element := tree.Find(action.On)
+	if element == nil {
+		return 0
+	}
+	return len([]rune(element.Text))
+}
+
 func resolveCoordinates(action verifier.Action, tree *hierarchy.Tree) (int, int, bool) {
 	// When On is empty, X/Y are authoritative (web V8 path emits coordinates
 	// directly from getBoundingClientRect; the runtime nullifies unresolved

internal/runner/runner_test.go

@@ -550,6 +550,52 @@ func TestRunner_LogsWaitForIdleDriverErrors(t *testing.T) {
 	}
 }
 
+func TestApplyAction_InputTextErasesExistingTextBeforeTyping(t *testing.T) {
+	tree, err := hierarchy.Parse(`{"attributes":{"resource-id":"root","bounds":"[0,0,1080,2340]"},"children":[
+		{"attributes":{"resource-id":"username","text":"stale-value","bounds":"[10,10,500,100]"},"children":[]}
+	]}`)
+	if err != nil {
+		t.Fatalf("Parse: %v", err)
+	}
+	driverMock := mockdriver.New()
+	action := verifier.Action{Kind: verifier.ActionKindInputText, On: "id:username", Text: "alice"}
+
+	if err := applyAction(context.Background(), driverMock, action, tree); err != nil {
+		t.Fatalf("applyAction: %v", err)
+	}
+	actions := driverMock.Actions()
+	if len(actions) != 3 {
+		t.Fatalf("want tap, erase, input; got %v", actions)
+	}
+	if actions[0].Kind != mockdriver.ActionTap {
+		t.Errorf("first action = %v, want tap", actions[0].Kind)
+	}
+	if actions[1].Kind != mockdriver.ActionEraseText || actions[1].CharacterCount != len("stale-value") {
+		t.Errorf("second action = %+v, want erase_text of %d characters", actions[1], len("stale-value"))
+	}
+	if actions[2].Kind != mockdriver.ActionInputText || actions[2].Text != "alice" {
+		t.Errorf("third action = %+v, want input_text alice", actions[2])
+	}
+}
+
+func TestApplyAction_InputTextSkipsEraseWhenTargetEmpty(t *testing.T) {
+	tree, err := hierarchy.Parse(`{"attributes":{"resource-id":"root","bounds":"[0,0,1080,2340]"},"children":[
+		{"attributes":{"resource-id":"username","bounds":"[10,10,500,100]"},"children":[]}
+	]}`)
+	if err != nil {
+		t.Fatalf("Parse: %v", err)
+	}
+	driverMock := mockdriver.New()
+	action := verifier.Action{Kind: verifier.ActionKindInputText, On: "id:username", Text: "alice"}
+
+	if err := applyAction(context.Background(), driverMock, action, tree); err != nil {
+		t.Fatalf("applyAction: %v", err)
+	}
+	if containsAction(driverMock.Actions(), mockdriver.ActionEraseText, "") {
+		t.Errorf("empty field must not be erased: %v", driverMock.Actions())
+	}
+}
+
 func TestApplyAction_InputTextSurfacesFocusTapError(t *testing.T) {
 	t.Run("selector focus tap fails", func(t *testing.T) {
 		driverMock := mockdriver.New()

proto/driverpb/driver.pb.go

@@ -213,6 +213,50 @@ func (x *Text) GetValue() string {
 	return ""
 }
 
+type EraseTextRequest struct {
+	state          protoimpl.MessageState `protogen:"open.v1"`
+	CharacterCount int32                  `protobuf:"varint,1,opt,name=character_count,json=characterCount,proto3" json:"character_count,omitempty"`
+	unknownFields  protoimpl.UnknownFields
+	sizeCache      protoimpl.SizeCache
+}
+
+func (x *EraseTextRequest) Reset() {
+	*x = EraseTextRequest{}
+	mi := &file_driverpb_driver_proto_msgTypes[4]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *EraseTextRequest) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*EraseTextRequest) ProtoMessage() {}
+
+func (x *EraseTextRequest) ProtoReflect() protoreflect.Message {
+	mi := &file_driverpb_driver_proto_msgTypes[4]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use EraseTextRequest.ProtoReflect.Descriptor instead.
+func (*EraseTextRequest) Descriptor() ([]byte, []int) {
+	return file_driverpb_driver_proto_rawDescGZIP(), []int{4}
+}
+
+func (x *EraseTextRequest) GetCharacterCount() int32 {
+	if x != nil {
+		return x.CharacterCount
+	}
+	return 0
+}
+
 type Selector struct {
 	state         protoimpl.MessageState `protogen:"open.v1"`
 	Value         string                 `protobuf:"bytes,1,opt,name=value,proto3" json:"value,omitempty"`
@@ -222,7 +266,7 @@ type Selector struct {
 
 func (x *Selector) Reset() {
 	*x = Selector{}
-	mi := &file_driverpb_driver_proto_msgTypes[4]
+	mi := &file_driverpb_driver_proto_msgTypes[5]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -234,7 +278,7 @@ func (x *Selector) String() string {
 func (*Selector) ProtoMessage() {}
 
 func (x *Selector) ProtoReflect() protoreflect.Message {
-	mi := &file_driverpb_driver_proto_msgTypes[4]
+	mi := &file_driverpb_driver_proto_msgTypes[5]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -247,7 +291,7 @@ func (x *Selector) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use Selector.ProtoReflect.Descriptor instead.
 func (*Selector) Descriptor() ([]byte, []int) {
-	return file_driverpb_driver_proto_rawDescGZIP(), []int{4}
+	return file_driverpb_driver_proto_rawDescGZIP(), []int{5}
 }
 
 func (x *Selector) GetValue() string {
@@ -268,7 +312,7 @@ type Image struct {
 
 func (x *Image) Reset() {
 	*x = Image{}
-	mi := &file_driverpb_driver_proto_msgTypes[5]
+	mi := &file_driverpb_driver_proto_msgTypes[6]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -280,7 +324,7 @@ func (x *Image) String() string {
 func (*Image) ProtoMessage() {}
 
 func (x *Image) ProtoReflect() protoreflect.Message {
-	mi := &file_driverpb_driver_proto_msgTypes[5]
+	mi := &file_driverpb_driver_proto_msgTypes[6]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -293,7 +337,7 @@ func (x *Image) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use Image.ProtoReflect.Descriptor instead.
 func (*Image) Descriptor() ([]byte, []int) {
-	return file_driverpb_driver_proto_rawDescGZIP(), []int{5}
+	return file_driverpb_driver_proto_rawDescGZIP(), []int{6}
 }
 
 func (x *Image) GetPng() []byte {
@@ -326,7 +370,7 @@ type HierarchyJSON struct {
 
 func (x *HierarchyJSON) Reset() {
 	*x = HierarchyJSON{}
-	mi := &file_driverpb_driver_proto_msgTypes[6]
+	mi := &file_driverpb_driver_proto_msgTypes[7]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -338,7 +382,7 @@ func (x *HierarchyJSON) String() string {
 func (*HierarchyJSON) ProtoMessage() {}
 
 func (x *HierarchyJSON) ProtoReflect() protoreflect.Message {
-	mi := &file_driverpb_driver_proto_msgTypes[6]
+	mi := &file_driverpb_driver_proto_msgTypes[7]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -351,7 +395,7 @@ func (x *HierarchyJSON) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use HierarchyJSON.ProtoReflect.Descriptor instead.
 func (*HierarchyJSON) Descriptor() ([]byte, []int) {
-	return file_driverpb_driver_proto_rawDescGZIP(), []int{6}
+	return file_driverpb_driver_proto_rawDescGZIP(), []int{7}
 }
 
 func (x *HierarchyJSON) GetJson() string {
@@ -371,7 +415,7 @@ type SnapshotResponse struct {
 
 func (x *SnapshotResponse) Reset() {
 	*x = SnapshotResponse{}
-	mi := &file_driverpb_driver_proto_msgTypes[7]
+	mi := &file_driverpb_driver_proto_msgTypes[8]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -383,7 +427,7 @@ func (x *SnapshotResponse) String() string {
 func (*SnapshotResponse) ProtoMessage() {}
 
 func (x *SnapshotResponse) ProtoReflect() protoreflect.Message {
-	mi := &file_driverpb_driver_proto_msgTypes[7]
+	mi := &file_driverpb_driver_proto_msgTypes[8]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -396,7 +440,7 @@ func (x *SnapshotResponse) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use SnapshotResponse.ProtoReflect.Descriptor instead.
 func (*SnapshotResponse) Descriptor() ([]byte, []int) {
-	return file_driverpb_driver_proto_rawDescGZIP(), []int{7}
+	return file_driverpb_driver_proto_rawDescGZIP(), []int{8}
 }
 
 func (x *SnapshotResponse) GetHierarchy() *HierarchyJSON {
@@ -422,7 +466,7 @@ type Duration struct {
 
 func (x *Duration) Reset() {
 	*x = Duration{}
-	mi := &file_driverpb_driver_proto_msgTypes[8]
+	mi := &file_driverpb_driver_proto_msgTypes[9]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -434,7 +478,7 @@ func (x *Duration) String() string {
 func (*Duration) ProtoMessage() {}
 
 func (x *Duration) ProtoReflect() protoreflect.Message {
-	mi := &file_driverpb_driver_proto_msgTypes[8]
+	mi := &file_driverpb_driver_proto_msgTypes[9]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -447,7 +491,7 @@ func (x *Duration) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use Duration.ProtoReflect.Descriptor instead.
 func (*Duration) Descriptor() ([]byte, []int) {
-	return file_driverpb_driver_proto_rawDescGZIP(), []int{8}
+	return file_driverpb_driver_proto_rawDescGZIP(), []int{9}
 }
 
 func (x *Duration) GetMillis() int64 {
@@ -468,7 +512,7 @@ type HealthStatus struct {
 
 func (x *HealthStatus) Reset() {
 	*x = HealthStatus{}
-	mi := &file_driverpb_driver_proto_msgTypes[9]
+	mi := &file_driverpb_driver_proto_msgTypes[10]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -480,7 +524,7 @@ func (x *HealthStatus) String() string {
 func (*HealthStatus) ProtoMessage() {}
 
 func (x *HealthStatus) ProtoReflect() protoreflect.Message {
-	mi := &file_driverpb_driver_proto_msgTypes[9]
+	mi := &file_driverpb_driver_proto_msgTypes[10]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -493,7 +537,7 @@ func (x *HealthStatus) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use HealthStatus.ProtoReflect.Descriptor instead.
 func (*HealthStatus) Descriptor() ([]byte, []int) {
-	return file_driverpb_driver_proto_rawDescGZIP(), []int{9}
+	return file_driverpb_driver_proto_rawDescGZIP(), []int{10}
 }
 
 func (x *HealthStatus) GetReady() bool {
@@ -528,7 +572,7 @@ type SwipeRequest struct {
 
 func (x *SwipeRequest) Reset() {
 	*x = SwipeRequest{}
-	mi := &file_driverpb_driver_proto_msgTypes[10]
+	mi := &file_driverpb_driver_proto_msgTypes[11]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -540,7 +584,7 @@ func (x *SwipeRequest) String() string {
 func (*SwipeRequest) ProtoMessage() {}
 
 func (x *SwipeRequest) ProtoReflect() protoreflect.Message {
-	mi := &file_driverpb_driver_proto_msgTypes[10]
+	mi := &file_driverpb_driver_proto_msgTypes[11]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -553,7 +597,7 @@ func (x *SwipeRequest) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use SwipeRequest.ProtoReflect.Descriptor instead.
 func (*SwipeRequest) Descriptor() ([]byte, []int) {
-	return file_driverpb_driver_proto_rawDescGZIP(), []int{10}
+	return file_driverpb_driver_proto_rawDescGZIP(), []int{11}
 }
 
 func (x *SwipeRequest) GetFrom() *Point {
@@ -588,7 +632,7 @@ type PressKeyRequest struct {
 
 func (x *PressKeyRequest) Reset() {
 	*x = PressKeyRequest{}
-	mi := &file_driverpb_driver_proto_msgTypes[11]
+	mi := &file_driverpb_driver_proto_msgTypes[12]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -600,7 +644,7 @@ func (x *PressKeyRequest) String() string {
 func (*PressKeyRequest) ProtoMessage() {}
 
 func (x *PressKeyRequest) ProtoReflect() protoreflect.Message {
-	mi := &file_driverpb_driver_proto_msgTypes[11]
+	mi := &file_driverpb_driver_proto_msgTypes[12]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -613,7 +657,7 @@ func (x *PressKeyRequest) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use PressKeyRequest.ProtoReflect.Descriptor instead.
 func (*PressKeyRequest) Descriptor() ([]byte, []int) {
-	return file_driverpb_driver_proto_rawDescGZIP(), []int{11}
+	return file_driverpb_driver_proto_rawDescGZIP(), []int{12}
 }
 
 func (x *PressKeyRequest) GetKey() string {
@@ -636,7 +680,7 @@ type RecentLogsRequest struct {
 
 func (x *RecentLogsRequest) Reset() {
 	*x = RecentLogsRequest{}
-	mi := &file_driverpb_driver_proto_msgTypes[12]
+	mi := &file_driverpb_driver_proto_msgTypes[13]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -648,7 +692,7 @@ func (x *RecentLogsRequest) String() string {
 func (*RecentLogsRequest) ProtoMessage() {}
 
 func (x *RecentLogsRequest) ProtoReflect() protoreflect.Message {
-	mi := &file_driverpb_driver_proto_msgTypes[12]
+	mi := &file_driverpb_driver_proto_msgTypes[13]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -661,7 +705,7 @@ func (x *RecentLogsRequest) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use RecentLogsRequest.ProtoReflect.Descriptor instead.
 func (*RecentLogsRequest) Descriptor() ([]byte, []int) {
-	return file_driverpb_driver_proto_rawDescGZIP(), []int{12}
+	return file_driverpb_driver_proto_rawDescGZIP(), []int{13}
 }
 
 func (x *RecentLogsRequest) GetSinceUnixMillis() int64 {
@@ -687,7 +731,7 @@ type LogEntries struct {
 
 func (x *LogEntries) Reset() {
 	*x = LogEntries{}
-	mi := &file_driverpb_driver_proto_msgTypes[13]
+	mi := &file_driverpb_driver_proto_msgTypes[14]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -699,7 +743,7 @@ func (x *LogEntries) String() string {
 func (*LogEntries) ProtoMessage() {}
 
 func (x *LogEntries) ProtoReflect() protoreflect.Message {
-	mi := &file_driverpb_driver_proto_msgTypes[13]
+	mi := &file_driverpb_driver_proto_msgTypes[14]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -712,7 +756,7 @@ func (x *LogEntries) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use LogEntries.ProtoReflect.Descriptor instead.
 func (*LogEntries) Descriptor() ([]byte, []int) {
-	return file_driverpb_driver_proto_rawDescGZIP(), []int{13}
+	return file_driverpb_driver_proto_rawDescGZIP(), []int{14}
 }
 
 func (x *LogEntries) GetEntries() []*LogEntry {
@@ -734,7 +778,7 @@ type LogEntry struct {
 
 func (x *LogEntry) Reset() {
 	*x = LogEntry{}
-	mi := &file_driverpb_driver_proto_msgTypes[14]
+	mi := &file_driverpb_driver_proto_msgTypes[15]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -746,7 +790,7 @@ func (x *LogEntry) String() string {
 func (*LogEntry) ProtoMessage() {}
 
 func (x *LogEntry) ProtoReflect() protoreflect.Message {
-	mi := &file_driverpb_driver_proto_msgTypes[14]
+	mi := &file_driverpb_driver_proto_msgTypes[15]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -759,7 +803,7 @@ func (x *LogEntry) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use LogEntry.ProtoReflect.Descriptor instead.
 func (*LogEntry) Descriptor() ([]byte, []int) {
-	return file_driverpb_driver_proto_rawDescGZIP(), []int{14}
+	return file_driverpb_driver_proto_rawDescGZIP(), []int{15}
 }
 
 func (x *LogEntry) GetUnixMillis() int64 {
@@ -799,7 +843,7 @@ type MetricsRequest struct {
 
 func (x *MetricsRequest) Reset() {
 	*x = MetricsRequest{}
-	mi := &file_driverpb_driver_proto_msgTypes[15]
+	mi := &file_driverpb_driver_proto_msgTypes[16]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -811,7 +855,7 @@ func (x *MetricsRequest) String() string {
 func (*MetricsRequest) ProtoMessage() {}
 
 func (x *MetricsRequest) ProtoReflect() protoreflect.Message {
-	mi := &file_driverpb_driver_proto_msgTypes[15]
+	mi := &file_driverpb_driver_proto_msgTypes[16]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -824,7 +868,7 @@ func (x *MetricsRequest) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use MetricsRequest.ProtoReflect.Descriptor instead.
 func (*MetricsRequest) Descriptor() ([]byte, []int) {
-	return file_driverpb_driver_proto_rawDescGZIP(), []int{15}
+	return file_driverpb_driver_proto_rawDescGZIP(), []int{16}
 }
 
 func (x *MetricsRequest) GetBundleId() string {
@@ -845,7 +889,7 @@ type MetricsResponse struct {
 
 func (x *MetricsResponse) Reset() {
 	*x = MetricsResponse{}
-	mi := &file_driverpb_driver_proto_msgTypes[16]
+	mi := &file_driverpb_driver_proto_msgTypes[17]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -857,7 +901,7 @@ func (x *MetricsResponse) String() string {
 func (*MetricsResponse) ProtoMessage() {}
 
 func (x *MetricsResponse) ProtoReflect() protoreflect.Message {
-	mi := &file_driverpb_driver_proto_msgTypes[16]
+	mi := &file_driverpb_driver_proto_msgTypes[17]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -870,7 +914,7 @@ func (x *MetricsResponse) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use MetricsResponse.ProtoReflect.Descriptor instead.
 func (*MetricsResponse) Descriptor() ([]byte, []int) {
-	return file_driverpb_driver_proto_rawDescGZIP(), []int{16}
+	return file_driverpb_driver_proto_rawDescGZIP(), []int{17}
 }
 
 func (x *MetricsResponse) GetCpuPercent() float64 {
@@ -912,7 +956,9 @@ const file_driverpb_driver_proto_rawDesc = "" +
 	"\x01x\x18\x01 \x01(\x05R\x01x\x12\f\n" +
 	"\x01y\x18\x02 \x01(\x05R\x01y\"\x1c\n" +
 	"\x04Text\x12\x14\n" +
-	"\x05value\x18\x01 \x01(\tR\x05value\" \n" +
+	"\x05value\x18\x01 \x01(\tR\x05value\";\n" +
+	"\x10EraseTextRequest\x12'\n" +
+	"\x0fcharacter_count\x18\x01 \x01(\x05R\x0echaracterCount\" \n" +
 	"\bSelector\x12\x14\n" +
 	"\x05value\x18\x01 \x01(\tR\x05value\"G\n" +
 	"\x05Image\x12\x10\n" +
@@ -957,13 +1003,16 @@ const file_driverpb_driver_proto_rawDesc = "" +
 	"cpuPercent\x12\x1d\n" +
 	"\n" +
 	"heap_bytes\x18\x02 \x01(\x03R\theapBytes\x12,\n" +
-	"\x12total_memory_bytes\x18\x03 \x01(\x03R\x10totalMemoryBytes2\xff\b\n" +
+	"\x12total_memory_bytes\x18\x03 \x01(\x03R\x10totalMemoryBytes2\x98\n" +
+	"\n" +
 	"\x06Driver\x12J\n" +
 	"\x06Launch\x12#.sanderling.driver.v1.LaunchRequest\x1a\x1b.sanderling.driver.v1.Empty\x12E\n" +
 	"\tTerminate\x12\x1b.sanderling.driver.v1.Empty\x1a\x1b.sanderling.driver.v1.Empty\x12?\n" +
-	"\x03Tap\x12\x1b.sanderling.driver.v1.Point\x1a\x1b.sanderling.driver.v1.Empty\x12J\n" +
+	"\x03Tap\x12\x1b.sanderling.driver.v1.Point\x1a\x1b.sanderling.driver.v1.Empty\x12E\n" +
+	"\tDoubleTap\x12\x1b.sanderling.driver.v1.Point\x1a\x1b.sanderling.driver.v1.Empty\x12J\n" +
 	"\vTapSelector\x12\x1e.sanderling.driver.v1.Selector\x1a\x1b.sanderling.driver.v1.Empty\x12D\n" +
-	"\tInputText\x12\x1a.sanderling.driver.v1.Text\x1a\x1b.sanderling.driver.v1.Empty\x12H\n" +
+	"\tInputText\x12\x1a.sanderling.driver.v1.Text\x1a\x1b.sanderling.driver.v1.Empty\x12P\n" +
+	"\tEraseText\x12&.sanderling.driver.v1.EraseTextRequest\x1a\x1b.sanderling.driver.v1.Empty\x12H\n" +
 	"\x05Swipe\x12\".sanderling.driver.v1.SwipeRequest\x1a\x1b.sanderling.driver.v1.Empty\x12N\n" +
 	"\bPressKey\x12%.sanderling.driver.v1.PressKeyRequest\x1a\x1b.sanderling.driver.v1.Empty\x12E\n" +
 	"\tLongPress\x12\x1b.sanderling.driver.v1.Point\x1a\x1b.sanderling.driver.v1.Empty\x12F\n" +
@@ -990,66 +1039,71 @@ func file_driverpb_driver_proto_rawDescGZIP() []byte {
 	return file_driverpb_driver_proto_rawDescData
 }
 
-var file_driverpb_driver_proto_msgTypes = make([]protoimpl.MessageInfo, 18)
+var file_driverpb_driver_proto_msgTypes = make([]protoimpl.MessageInfo, 19)
 var file_driverpb_driver_proto_goTypes = []any{
 	(*Empty)(nil),             // 0: sanderling.driver.v1.Empty
 	(*LaunchRequest)(nil),     // 1: sanderling.driver.v1.LaunchRequest
 	(*Point)(nil),             // 2: sanderling.driver.v1.Point
 	(*Text)(nil),              // 3: sanderling.driver.v1.Text
-	(*Selector)(nil),          // 4: sanderling.driver.v1.Selector
+	(*EraseTextRequest)(nil),  // 4: sanderling.driver.v1.EraseTextRequest
-	(*Image)(nil),             // 5: sanderling.driver.v1.Image
+	(*Selector)(nil),          // 5: sanderling.driver.v1.Selector
-	(*HierarchyJSON)(nil),     // 6: sanderling.driver.v1.HierarchyJSON
+	(*Image)(nil),             // 6: sanderling.driver.v1.Image
-	(*SnapshotResponse)(nil),  // 7: sanderling.driver.v1.SnapshotResponse
+	(*HierarchyJSON)(nil),     // 7: sanderling.driver.v1.HierarchyJSON
-	(*Duration)(nil),          // 8: sanderling.driver.v1.Duration
+	(*SnapshotResponse)(nil),  // 8: sanderling.driver.v1.SnapshotResponse
-	(*HealthStatus)(nil),      // 9: sanderling.driver.v1.HealthStatus
+	(*Duration)(nil),          // 9: sanderling.driver.v1.Duration
-	(*SwipeRequest)(nil),      // 10: sanderling.driver.v1.SwipeRequest
+	(*HealthStatus)(nil),      // 10: sanderling.driver.v1.HealthStatus
-	(*PressKeyRequest)(nil),   // 11: sanderling.driver.v1.PressKeyRequest
+	(*SwipeRequest)(nil),      // 11: sanderling.driver.v1.SwipeRequest
-	(*RecentLogsRequest)(nil), // 12: sanderling.driver.v1.RecentLogsRequest
+	(*PressKeyRequest)(nil),   // 12: sanderling.driver.v1.PressKeyRequest
-	(*LogEntries)(nil),        // 13: sanderling.driver.v1.LogEntries
+	(*RecentLogsRequest)(nil), // 13: sanderling.driver.v1.RecentLogsRequest
-	(*LogEntry)(nil),          // 14: sanderling.driver.v1.LogEntry
+	(*LogEntries)(nil),        // 14: sanderling.driver.v1.LogEntries
-	(*MetricsRequest)(nil),    // 15: sanderling.driver.v1.MetricsRequest
+	(*LogEntry)(nil),          // 15: sanderling.driver.v1.LogEntry
-	(*MetricsResponse)(nil),   // 16: sanderling.driver.v1.MetricsResponse
+	(*MetricsRequest)(nil),    // 16: sanderling.driver.v1.MetricsRequest
-	nil,                       // 17: sanderling.driver.v1.LaunchRequest.EnvEntry
+	(*MetricsResponse)(nil),   // 17: sanderling.driver.v1.MetricsResponse
+	nil,                       // 18: sanderling.driver.v1.LaunchRequest.EnvEntry
 }
 var file_driverpb_driver_proto_depIdxs = []int32{
-	17, // 0: sanderling.driver.v1.LaunchRequest.env:type_name -> sanderling.driver.v1.LaunchRequest.EnvEntry
+	18, // 0: sanderling.driver.v1.LaunchRequest.env:type_name -> sanderling.driver.v1.LaunchRequest.EnvEntry
-	6,  // 1: sanderling.driver.v1.SnapshotResponse.hierarchy:type_name -> sanderling.driver.v1.HierarchyJSON
+	7,  // 1: sanderling.driver.v1.SnapshotResponse.hierarchy:type_name -> sanderling.driver.v1.HierarchyJSON
-	5,  // 2: sanderling.driver.v1.SnapshotResponse.screenshot:type_name -> sanderling.driver.v1.Image
+	6,  // 2: sanderling.driver.v1.SnapshotResponse.screenshot:type_name -> sanderling.driver.v1.Image
 	2,  // 3: sanderling.driver.v1.SwipeRequest.from:type_name -> sanderling.driver.v1.Point
 	2,  // 4: sanderling.driver.v1.SwipeRequest.to:type_name -> sanderling.driver.v1.Point
-	14, // 5: sanderling.driver.v1.LogEntries.entries:type_name -> sanderling.driver.v1.LogEntry
+	15, // 5: sanderling.driver.v1.LogEntries.entries:type_name -> sanderling.driver.v1.LogEntry
 	1,  // 6: sanderling.driver.v1.Driver.Launch:input_type -> sanderling.driver.v1.LaunchRequest
 	0,  // 7: sanderling.driver.v1.Driver.Terminate:input_type -> sanderling.driver.v1.Empty
 	2,  // 8: sanderling.driver.v1.Driver.Tap:input_type -> sanderling.driver.v1.Point
-	4,  // 9: sanderling.driver.v1.Driver.TapSelector:input_type -> sanderling.driver.v1.Selector
+	2,  // 9: sanderling.driver.v1.Driver.DoubleTap:input_type -> sanderling.driver.v1.Point
-	3,  // 10: sanderling.driver.v1.Driver.InputText:input_type -> sanderling.driver.v1.Text
+	5,  // 10: sanderling.driver.v1.Driver.TapSelector:input_type -> sanderling.driver.v1.Selector
-	10, // 11: sanderling.driver.v1.Driver.Swipe:input_type -> sanderling.driver.v1.SwipeRequest
+	3,  // 11: sanderling.driver.v1.Driver.InputText:input_type -> sanderling.driver.v1.Text
-	11, // 12: sanderling.driver.v1.Driver.PressKey:input_type -> sanderling.driver.v1.PressKeyRequest
+	4,  // 12: sanderling.driver.v1.Driver.EraseText:input_type -> sanderling.driver.v1.EraseTextRequest
-	2,  // 13: sanderling.driver.v1.Driver.LongPress:input_type -> sanderling.driver.v1.Point
+	11, // 13: sanderling.driver.v1.Driver.Swipe:input_type -> sanderling.driver.v1.SwipeRequest
-	0,  // 14: sanderling.driver.v1.Driver.Screenshot:input_type -> sanderling.driver.v1.Empty
+	12, // 14: sanderling.driver.v1.Driver.PressKey:input_type -> sanderling.driver.v1.PressKeyRequest
-	0,  // 15: sanderling.driver.v1.Driver.Hierarchy:input_type -> sanderling.driver.v1.Empty
+	2,  // 15: sanderling.driver.v1.Driver.LongPress:input_type -> sanderling.driver.v1.Point
-	0,  // 16: sanderling.driver.v1.Driver.Snapshot:input_type -> sanderling.driver.v1.Empty
+	0,  // 16: sanderling.driver.v1.Driver.Screenshot:input_type -> sanderling.driver.v1.Empty
-	12, // 17: sanderling.driver.v1.Driver.RecentLogs:input_type -> sanderling.driver.v1.RecentLogsRequest
+	0,  // 17: sanderling.driver.v1.Driver.Hierarchy:input_type -> sanderling.driver.v1.Empty
-	8,  // 18: sanderling.driver.v1.Driver.WaitForIdle:input_type -> sanderling.driver.v1.Duration
+	0,  // 18: sanderling.driver.v1.Driver.Snapshot:input_type -> sanderling.driver.v1.Empty
-	0,  // 19: sanderling.driver.v1.Driver.Health:input_type -> sanderling.driver.v1.Empty
+	13, // 19: sanderling.driver.v1.Driver.RecentLogs:input_type -> sanderling.driver.v1.RecentLogsRequest
-	15, // 20: sanderling.driver.v1.Driver.Metrics:input_type -> sanderling.driver.v1.MetricsRequest
+	9,  // 20: sanderling.driver.v1.Driver.WaitForIdle:input_type -> sanderling.driver.v1.Duration
-	0,  // 21: sanderling.driver.v1.Driver.Launch:output_type -> sanderling.driver.v1.Empty
+	0,  // 21: sanderling.driver.v1.Driver.Health:input_type -> sanderling.driver.v1.Empty
-	0,  // 22: sanderling.driver.v1.Driver.Terminate:output_type -> sanderling.driver.v1.Empty
+	16, // 22: sanderling.driver.v1.Driver.Metrics:input_type -> sanderling.driver.v1.MetricsRequest
-	0,  // 23: sanderling.driver.v1.Driver.Tap:output_type -> sanderling.driver.v1.Empty
+	0,  // 23: sanderling.driver.v1.Driver.Launch:output_type -> sanderling.driver.v1.Empty
-	0,  // 24: sanderling.driver.v1.Driver.TapSelector:output_type -> sanderling.driver.v1.Empty
+	0,  // 24: sanderling.driver.v1.Driver.Terminate:output_type -> sanderling.driver.v1.Empty
-	0,  // 25: sanderling.driver.v1.Driver.InputText:output_type -> sanderling.driver.v1.Empty
+	0,  // 25: sanderling.driver.v1.Driver.Tap:output_type -> sanderling.driver.v1.Empty
-	0,  // 26: sanderling.driver.v1.Driver.Swipe:output_type -> sanderling.driver.v1.Empty
+	0,  // 26: sanderling.driver.v1.Driver.DoubleTap:output_type -> sanderling.driver.v1.Empty
-	0,  // 27: sanderling.driver.v1.Driver.PressKey:output_type -> sanderling.driver.v1.Empty
+	0,  // 27: sanderling.driver.v1.Driver.TapSelector:output_type -> sanderling.driver.v1.Empty
-	0,  // 28: sanderling.driver.v1.Driver.LongPress:output_type -> sanderling.driver.v1.Empty
+	0,  // 28: sanderling.driver.v1.Driver.InputText:output_type -> sanderling.driver.v1.Empty
-	5,  // 29: sanderling.driver.v1.Driver.Screenshot:output_type -> sanderling.driver.v1.Image
+	0,  // 29: sanderling.driver.v1.Driver.EraseText:output_type -> sanderling.driver.v1.Empty
-	6,  // 30: sanderling.driver.v1.Driver.Hierarchy:output_type -> sanderling.driver.v1.HierarchyJSON
+	0,  // 30: sanderling.driver.v1.Driver.Swipe:output_type -> sanderling.driver.v1.Empty
-	7,  // 31: sanderling.driver.v1.Driver.Snapshot:output_type -> sanderling.driver.v1.SnapshotResponse
+	0,  // 31: sanderling.driver.v1.Driver.PressKey:output_type -> sanderling.driver.v1.Empty
-	13, // 32: sanderling.driver.v1.Driver.RecentLogs:output_type -> sanderling.driver.v1.LogEntries
+	0,  // 32: sanderling.driver.v1.Driver.LongPress:output_type -> sanderling.driver.v1.Empty
-	0,  // 33: sanderling.driver.v1.Driver.WaitForIdle:output_type -> sanderling.driver.v1.Empty
+	6,  // 33: sanderling.driver.v1.Driver.Screenshot:output_type -> sanderling.driver.v1.Image
-	9,  // 34: sanderling.driver.v1.Driver.Health:output_type -> sanderling.driver.v1.HealthStatus
+	7,  // 34: sanderling.driver.v1.Driver.Hierarchy:output_type -> sanderling.driver.v1.HierarchyJSON
-	16, // 35: sanderling.driver.v1.Driver.Metrics:output_type -> sanderling.driver.v1.MetricsResponse
+	8,  // 35: sanderling.driver.v1.Driver.Snapshot:output_type -> sanderling.driver.v1.SnapshotResponse
-	21, // [21:36] is the sub-list for method output_type
+	14, // 36: sanderling.driver.v1.Driver.RecentLogs:output_type -> sanderling.driver.v1.LogEntries
-	6,  // [6:21] is the sub-list for method input_type
+	0,  // 37: sanderling.driver.v1.Driver.WaitForIdle:output_type -> sanderling.driver.v1.Empty
+	10, // 38: sanderling.driver.v1.Driver.Health:output_type -> sanderling.driver.v1.HealthStatus
+	17, // 39: sanderling.driver.v1.Driver.Metrics:output_type -> sanderling.driver.v1.MetricsResponse
+	23, // [23:40] is the sub-list for method output_type
+	6,  // [6:23] is the sub-list for method input_type
 	6,  // [6:6] is the sub-list for extension type_name
 	6,  // [6:6] is the sub-list for extension extendee
 	0,  // [0:6] is the sub-list for field type_name
@@ -1066,7 +1120,7 @@ func file_driverpb_driver_proto_init() {
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: unsafe.Slice(unsafe.StringData(file_driverpb_driver_proto_rawDesc), len(file_driverpb_driver_proto_rawDesc)),
 			NumEnums:      0,
-			NumMessages:   18,
+			NumMessages:   19,
 			NumExtensions: 0,
 			NumServices:   1,
 		},

proto/driverpb/driver.proto

@@ -11,8 +11,16 @@ service Driver {
   rpc Terminate(Empty) returns (Empty);
 
   rpc Tap(Point) returns (Empty);
+  // DoubleTap lands two taps as close together as the platform allows.
+  // Composing two Tap calls from the client spreads them by hundreds of
+  // milliseconds on iOS, wide enough for navigation to interleave, which
+  // defeats double-submission testing.
+  rpc DoubleTap(Point) returns (Empty);
   rpc TapSelector(Selector) returns (Empty);
   rpc InputText(Text) returns (Empty);
+  // EraseText deletes characters from the focused field so InputText can
+  // replace existing content instead of appending to it.
+  rpc EraseText(EraseTextRequest) returns (Empty);
   rpc Swipe(SwipeRequest) returns (Empty);
   rpc PressKey(PressKeyRequest) returns (Empty);
   rpc LongPress(Point) returns (Empty);
@@ -47,6 +55,10 @@ message Text {
   string value = 1;
 }
 
+message EraseTextRequest {
+  int32 character_count = 1;
+}
+
 message Selector {
   string value = 1;
 }

proto/driverpb/driver_grpc.pb.go

@@ -22,8 +22,10 @@ const (
 	Driver_Launch_FullMethodName      = "/sanderling.driver.v1.Driver/Launch"
 	Driver_Terminate_FullMethodName   = "/sanderling.driver.v1.Driver/Terminate"
 	Driver_Tap_FullMethodName         = "/sanderling.driver.v1.Driver/Tap"
+	Driver_DoubleTap_FullMethodName   = "/sanderling.driver.v1.Driver/DoubleTap"
 	Driver_TapSelector_FullMethodName = "/sanderling.driver.v1.Driver/TapSelector"
 	Driver_InputText_FullMethodName   = "/sanderling.driver.v1.Driver/InputText"
+	Driver_EraseText_FullMethodName   = "/sanderling.driver.v1.Driver/EraseText"
 	Driver_Swipe_FullMethodName       = "/sanderling.driver.v1.Driver/Swipe"
 	Driver_PressKey_FullMethodName    = "/sanderling.driver.v1.Driver/PressKey"
 	Driver_LongPress_FullMethodName   = "/sanderling.driver.v1.Driver/LongPress"
@@ -43,8 +45,16 @@ type DriverClient interface {
 	Launch(ctx context.Context, in *LaunchRequest, opts ...grpc.CallOption) (*Empty, error)
 	Terminate(ctx context.Context, in *Empty, opts ...grpc.CallOption) (*Empty, error)
 	Tap(ctx context.Context, in *Point, opts ...grpc.CallOption) (*Empty, error)
+	// DoubleTap lands two taps as close together as the platform allows.
+	// Composing two Tap calls from the client spreads them by hundreds of
+	// milliseconds on iOS, wide enough for navigation to interleave, which
+	// defeats double-submission testing.
+	DoubleTap(ctx context.Context, in *Point, opts ...grpc.CallOption) (*Empty, error)
 	TapSelector(ctx context.Context, in *Selector, opts ...grpc.CallOption) (*Empty, error)
 	InputText(ctx context.Context, in *Text, opts ...grpc.CallOption) (*Empty, error)
+	// EraseText deletes characters from the focused field so InputText can
+	// replace existing content instead of appending to it.
+	EraseText(ctx context.Context, in *EraseTextRequest, opts ...grpc.CallOption) (*Empty, error)
 	Swipe(ctx context.Context, in *SwipeRequest, opts ...grpc.CallOption) (*Empty, error)
 	PressKey(ctx context.Context, in *PressKeyRequest, opts ...grpc.CallOption) (*Empty, error)
 	LongPress(ctx context.Context, in *Point, opts ...grpc.CallOption) (*Empty, error)
@@ -98,6 +108,16 @@ func (c *driverClient) Tap(ctx context.Context, in *Point, opts ...grpc.CallOpti
 	return out, nil
 }
 
+func (c *driverClient) DoubleTap(ctx context.Context, in *Point, opts ...grpc.CallOption) (*Empty, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(Empty)
+	err := c.cc.Invoke(ctx, Driver_DoubleTap_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
 func (c *driverClient) TapSelector(ctx context.Context, in *Selector, opts ...grpc.CallOption) (*Empty, error) {
 	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
 	out := new(Empty)
@@ -118,6 +138,16 @@ func (c *driverClient) InputText(ctx context.Context, in *Text, opts ...grpc.Cal
 	return out, nil
 }
 
+func (c *driverClient) EraseText(ctx context.Context, in *EraseTextRequest, opts ...grpc.CallOption) (*Empty, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(Empty)
+	err := c.cc.Invoke(ctx, Driver_EraseText_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
 func (c *driverClient) Swipe(ctx context.Context, in *SwipeRequest, opts ...grpc.CallOption) (*Empty, error) {
 	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
 	out := new(Empty)
@@ -225,8 +255,16 @@ type DriverServer interface {
 	Launch(context.Context, *LaunchRequest) (*Empty, error)
 	Terminate(context.Context, *Empty) (*Empty, error)
 	Tap(context.Context, *Point) (*Empty, error)
+	// DoubleTap lands two taps as close together as the platform allows.
+	// Composing two Tap calls from the client spreads them by hundreds of
+	// milliseconds on iOS, wide enough for navigation to interleave, which
+	// defeats double-submission testing.
+	DoubleTap(context.Context, *Point) (*Empty, error)
 	TapSelector(context.Context, *Selector) (*Empty, error)
 	InputText(context.Context, *Text) (*Empty, error)
+	// EraseText deletes characters from the focused field so InputText can
+	// replace existing content instead of appending to it.
+	EraseText(context.Context, *EraseTextRequest) (*Empty, error)
 	Swipe(context.Context, *SwipeRequest) (*Empty, error)
 	PressKey(context.Context, *PressKeyRequest) (*Empty, error)
 	LongPress(context.Context, *Point) (*Empty, error)
@@ -259,12 +297,18 @@ func (UnimplementedDriverServer) Terminate(context.Context, *Empty) (*Empty, err
 func (UnimplementedDriverServer) Tap(context.Context, *Point) (*Empty, error) {
 	return nil, status.Error(codes.Unimplemented, "method Tap not implemented")
 }
+func (UnimplementedDriverServer) DoubleTap(context.Context, *Point) (*Empty, error) {
+	return nil, status.Error(codes.Unimplemented, "method DoubleTap not implemented")
+}
 func (UnimplementedDriverServer) TapSelector(context.Context, *Selector) (*Empty, error) {
 	return nil, status.Error(codes.Unimplemented, "method TapSelector not implemented")
 }
 func (UnimplementedDriverServer) InputText(context.Context, *Text) (*Empty, error) {
 	return nil, status.Error(codes.Unimplemented, "method InputText not implemented")
 }
+func (UnimplementedDriverServer) EraseText(context.Context, *EraseTextRequest) (*Empty, error) {
+	return nil, status.Error(codes.Unimplemented, "method EraseText not implemented")
+}
 func (UnimplementedDriverServer) Swipe(context.Context, *SwipeRequest) (*Empty, error) {
 	return nil, status.Error(codes.Unimplemented, "method Swipe not implemented")
 }
@@ -370,6 +414,24 @@ func _Driver_Tap_Handler(srv interface{}, ctx context.Context, dec func(interfac
 	return interceptor(ctx, in, info, handler)
 }
 
+func _Driver_DoubleTap_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(Point)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(DriverServer).DoubleTap(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: Driver_DoubleTap_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(DriverServer).DoubleTap(ctx, req.(*Point))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
 func _Driver_TapSelector_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
 	in := new(Selector)
 	if err := dec(in); err != nil {
@@ -406,6 +468,24 @@ func _Driver_InputText_Handler(srv interface{}, ctx context.Context, dec func(in
 	return interceptor(ctx, in, info, handler)
 }
 
+func _Driver_EraseText_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(EraseTextRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(DriverServer).EraseText(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: Driver_EraseText_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(DriverServer).EraseText(ctx, req.(*EraseTextRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
 func _Driver_Swipe_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
 	in := new(SwipeRequest)
 	if err := dec(in); err != nil {
@@ -605,6 +685,10 @@ var Driver_ServiceDesc = grpc.ServiceDesc{
 			MethodName: "Tap",
 			Handler:    _Driver_Tap_Handler,
 		},
+		{
+			MethodName: "DoubleTap",
+			Handler:    _Driver_DoubleTap_Handler,
+		},
 		{
 			MethodName: "TapSelector",
 			Handler:    _Driver_TapSelector_Handler,
@@ -613,6 +697,10 @@ var Driver_ServiceDesc = grpc.ServiceDesc{
 			MethodName: "InputText",
 			Handler:    _Driver_InputText_Handler,
 		},
+		{
+			MethodName: "EraseText",
+			Handler:    _Driver_EraseText_Handler,
+		},
 		{
 			MethodName: "Swipe",
 			Handler:    _Driver_Swipe_Handler,

proto/driverpb/driver_test.go

@@ -16,8 +16,10 @@ func TestDriverServiceDescriptor(t *testing.T) {
 		"Launch":      true,
 		"Terminate":   true,
 		"Tap":         true,
+		"DoubleTap":   true,
 		"TapSelector": true,
 		"InputText":   true,
+		"EraseText":   true,
 		"Swipe":       true,
 		"PressKey":    true,
 		"LongPress":   true,

sidecar/src/main/kotlin/dev/sanderling/sidecar/DriverBackend.kt

@@ -4,8 +4,18 @@ interface DriverBackend {
     fun launch(bundleId: String, clearState: Boolean, env: Map<String, String> = emptyMap())
     fun terminate(bundleId: String)
     fun tap(x: Int, y: Int)
+
+    // doubleTap lands two taps as close together as the platform allows.
+    // The default composes two taps back-to-back; backends with higher
+    // per-tap latency override to tighten the gap.
+    fun doubleTap(x: Int, y: Int) {
+        tap(x, y)
+        tap(x, y)
+    }
+
     fun tapSelector(selector: String)
     fun inputText(text: String)
+    fun eraseText(characterCount: Int)
     fun swipe(fromX: Int, fromY: Int, toX: Int, toY: Int, durationMillis: Long)
     fun pressKey(key: String)
     fun longPress(x: Int, y: Int)
@@ -402,6 +412,16 @@ class StubDriverBackend(
         runAdb(listOf("shell", "input", "text", escapeForAdbInputText(text)))
     }
 
+    @Volatile var lastEraseCharacterCount: Int? = null
+        private set
+
+    override fun eraseText(characterCount: Int) {
+        lastEraseCharacterCount = characterCount
+        repeat(characterCount) {
+            runAdb(listOf("shell", "input", "keyevent", "KEYCODE_DEL"))
+        }
+    }
+
     @Volatile var lastSwipe: SwipeRecord? = null
         private set
     @Volatile var lastKey: String? = null
@@ -531,6 +551,8 @@ class MaestroDriverBackend(private val serial: String?) : DriverBackend {
 
     override fun inputText(text: String) = driver.inputText(text)
 
+    override fun eraseText(characterCount: Int) = driver.eraseText(characterCount)
+
     override fun swipe(fromX: Int, fromY: Int, toX: Int, toY: Int, durationMillis: Long) =
         driver.swipe(maestro.Point(fromX, fromY), maestro.Point(toX, toY), maxOf(durationMillis, 250L))
 
@@ -629,6 +651,7 @@ private fun pngHeight(bytes: ByteArray): Int {
 
 class IosDriverBackend(private val udid: String) : DriverBackend {
     private lateinit var driver: maestro.drivers.IOSDriver
+    private lateinit var localDevice: ios.LocalIOSDevice
     private val reconnectLock = java.util.concurrent.locks.ReentrantLock()
 
     init {
@@ -670,6 +693,7 @@ class IosDriverBackend(private val udid: String) : DriverBackend {
             deviceController = simctlDevice,
             insights = maestro.utils.NoopInsights,
         )
+        localDevice = device
         driver = maestro.drivers.IOSDriver(device, maestro.utils.NoopInsights)
         driver.open()
         warmup()
@@ -720,6 +744,19 @@ class IosDriverBackend(private val udid: String) : DriverBackend {
 
     override fun tap(x: Int, y: Int) = withReconnect { driver.tap(maestro.Point(x, y)) }
 
+    // The second tap request is already queued at the XCTest runner while the
+    // first executes, so the on-device gap collapses to the runner's
+    // turnaround instead of a full transport round trip. Sequential requests
+    // leave a gap wide enough for the app to navigate between the taps.
+    override fun doubleTap(x: Int, y: Int): Unit = withReconnect {
+        val point = maestro.Point(x, y)
+        val firstTap = java.util.concurrent.CompletableFuture.runAsync { driver.tap(point) }
+        Thread.sleep(40)
+        driver.tap(point)
+        firstTap.join()
+        Unit
+    }
+
     override fun longPress(x: Int, y: Int) = withReconnect { driver.longPress(maestro.Point(x, y)) }
 
     override fun tapSelector(selector: String) = withReconnect {
@@ -730,6 +767,8 @@ class IosDriverBackend(private val udid: String) : DriverBackend {
 
     override fun inputText(text: String) = withReconnect { driver.inputText(text) }
 
+    override fun eraseText(characterCount: Int) = withReconnect { driver.eraseText(characterCount) }
+
     override fun swipe(fromX: Int, fromY: Int, toX: Int, toY: Int, durationMillis: Long) = withReconnect {
         driver.swipe(maestro.Point(fromX, fromY), maestro.Point(toX, toY), maxOf(durationMillis, 250L))
     }
@@ -750,7 +789,7 @@ class IosDriverBackend(private val udid: String) : DriverBackend {
 
     override fun hierarchy(): String = withReconnect {
         com.fasterxml.jackson.module.kotlin.jacksonObjectMapper()
-            .writeValueAsString(driver.contentDescriptor(false))
+            .writeValueAsString(iosAxElementToTreeNode(localDevice.viewHierarchy(false).axElement))
     }
 
     override fun recentLogs(sinceUnixMillis: Long, minLevel: String): List<LogLine> = emptyList()
@@ -784,3 +823,115 @@ private fun keyCodeToMaestro(adbKeyCode: String): maestro.KeyCode? {
         else -> null
     }
 }
+
+// XCUIElementType raw values that accept a tap. The XCTest hierarchy carries
+// no clickable flag, so tappability is derived from the element type that
+// XCUITest itself derives from the accessibility traits.
+internal val IOS_CLICKABLE_ELEMENT_TYPES = setOf(
+    9,  // button
+    10, // radioButton
+    12, // checkBox
+    14, // popUpButton
+    15, // comboBox
+    16, // menuButton
+    17, // toolbarButton
+    20, // key
+    37, // segmentedControl
+    40, // switch
+    41, // toggle
+    42, // link
+    54, // menuItem
+    75, // cell
+    79, // stepper
+    80, // tab
+)
+
+// XCUIElementType raw values that accept text input.
+internal val IOS_EDITABLE_ELEMENT_TYPES = setOf(
+    45, // searchField
+    49, // textField
+    50, // secureTextField
+    52, // textView
+)
+
+// XCUIElementType raw values that scroll.
+internal val IOS_SCROLLABLE_ELEMENT_TYPES = setOf(
+    26, // table
+    32, // collectionView
+    46, // scrollView
+    58, // webView
+)
+
+// Checkable element types and the value convention ("1" when on) mirror the
+// upstream content-descriptor mapping.
+internal val IOS_CHECKABLE_ELEMENT_TYPES = setOf(
+    12, // checkBox
+    40, // switch
+    41, // toggle
+)
+
+private val IOS_ELEMENT_TYPE_NAMES = arrayOf(
+    "Any", "Other", "Application", "Group", "Window", "Sheet", "Drawer",
+    "Alert", "Dialog", "Button", "RadioButton", "RadioGroup", "CheckBox",
+    "DisclosureTriangle", "PopUpButton", "ComboBox", "MenuButton",
+    "ToolbarButton", "Popover", "Keyboard", "Key", "NavigationBar", "TabBar",
+    "TabGroup", "Toolbar", "StatusBar", "Table", "TableRow", "TableColumn",
+    "Outline", "OutlineRow", "Browser", "CollectionView", "Slider",
+    "PageIndicator", "ProgressIndicator", "ActivityIndicator",
+    "SegmentedControl", "Picker", "PickerWheel", "Switch", "Toggle", "Link",
+    "Image", "Icon", "SearchField", "ScrollView", "ScrollBar", "StaticText",
+    "TextField", "SecureTextField", "DatePicker", "TextView", "Menu",
+    "MenuItem", "MenuBar", "MenuBarItem", "Map", "WebView", "IncrementArrow",
+    "DecrementArrow", "Timeline", "RatingIndicator", "ValueIndicator",
+    "SplitGroup", "Splitter", "RelevanceIndicator", "ColorWell", "HelpTag",
+    "Matte", "DockItem", "Ruler", "RulerMarker", "Grid", "LevelIndicator",
+    "Cell", "LayoutArea", "LayoutItem", "Handle", "Stepper", "Tab",
+    "TouchBar", "StatusItem",
+)
+
+internal fun iosElementTypeName(elementType: Int): String =
+    IOS_ELEMENT_TYPE_NAMES.getOrElse(elementType) { "Other" }
+
+// iosAxElementToTreeNode maps the raw XCTest accessibility tree to the
+// TreeNode JSON shape the runner parses. The upstream content-descriptor
+// mapping drops the element type, leaving no way to tell buttons and text
+// fields apart, so fuzz verbs found no tap or typing candidates on iOS.
+internal fun iosAxElementToTreeNode(element: hierarchy.AXElement): Map<String, Any?> {
+    val elementType = element.elementType
+    val title = element.title.orEmpty()
+    val value = element.value.orEmpty()
+    val label = element.label.orEmpty()
+    val editable = elementType in IOS_EDITABLE_ELEMENT_TYPES
+    val checked = elementType in IOS_CHECKABLE_ELEMENT_TYPES && value == "1"
+    // text carries the element's visible string, matching what Android
+    // surfaces in its text attribute. Editable fields expose only their
+    // typed content: their label is the field caption (e.g. "Email"), and
+    // leaking it into text would make an empty field look filled. Static
+    // text and buttons carry the visible string in the label.
+    val text = if (editable) value else title.ifEmpty { value }.ifEmpty { label }
+    val attributes = linkedMapOf(
+        "accessibilityText" to label,
+        "title" to title,
+        "value" to value,
+        "text" to text,
+        "hintText" to element.placeholderValue.orEmpty(),
+        "resource-id" to element.identifier.orEmpty(),
+        "bounds" to element.frame.boundsString,
+        "class" to iosElementTypeName(elementType),
+        "enabled" to element.enabled.toString(),
+        "focused" to element.hasFocus.toString(),
+        "selected" to element.selected.toString(),
+        "checked" to checked.toString(),
+        "scrollable" to (elementType in IOS_SCROLLABLE_ELEMENT_TYPES).toString(),
+    )
+    return linkedMapOf(
+        "attributes" to attributes,
+        "children" to element.children.map { iosAxElementToTreeNode(it) },
+        "clickable" to (elementType in IOS_CLICKABLE_ELEMENT_TYPES),
+        "enabled" to element.enabled,
+        "focused" to element.hasFocus,
+        "checked" to checked,
+        "selected" to element.selected,
+        "editable" to editable,
+    )
+}

sidecar/src/main/kotlin/dev/sanderling/sidecar/DriverService.kt

@@ -4,6 +4,7 @@ import com.google.protobuf.ByteString
 import dev.sanderling.driver.v1.DriverGrpc
 import dev.sanderling.driver.v1.Duration
 import dev.sanderling.driver.v1.Empty
+import dev.sanderling.driver.v1.EraseTextRequest
 import dev.sanderling.driver.v1.HealthStatus
 import dev.sanderling.driver.v1.HierarchyJSON
 import dev.sanderling.driver.v1.Image
@@ -53,6 +54,13 @@ class DriverService(
         }
     }
 
+    override fun doubleTap(request: Point, responseObserver: StreamObserver<Empty>) {
+        runRpc(responseObserver) {
+            backend.doubleTap(request.x, request.y)
+            Empty.getDefaultInstance()
+        }
+    }
+
     override fun longPress(request: Point, responseObserver: StreamObserver<Empty>) {
         runRpc(responseObserver) {
             backend.longPress(request.x, request.y)
@@ -74,6 +82,13 @@ class DriverService(
         }
     }
 
+    override fun eraseText(request: EraseTextRequest, responseObserver: StreamObserver<Empty>) {
+        runRpc(responseObserver) {
+            backend.eraseText(request.characterCount)
+            Empty.getDefaultInstance()
+        }
+    }
+
     override fun swipe(request: SwipeRequest, responseObserver: StreamObserver<Empty>) {
         runRpc(responseObserver) {
             val from = request.from

sidecar/src/test/kotlin/dev/sanderling/sidecar/DriverServiceTest.kt

@@ -3,6 +3,7 @@ package dev.sanderling.sidecar
 import dev.sanderling.driver.v1.DriverGrpc
 import dev.sanderling.driver.v1.Duration
 import dev.sanderling.driver.v1.Empty
+import dev.sanderling.driver.v1.EraseTextRequest
 import dev.sanderling.driver.v1.LaunchRequest
 import dev.sanderling.driver.v1.Point
 import dev.sanderling.driver.v1.PressKeyRequest
@@ -82,6 +83,42 @@ class DriverServiceTest {
         assertEquals("hello world", backend.lastInputText)
     }
 
+    @Test fun doubleTapDefaultComposesTwoTaps() {
+        // Interface delegation would bind the default doubleTap to the
+        // delegate, bypassing the tap override, so implement the interface
+        // directly.
+        val taps = mutableListOf<Pair<Int, Int>>()
+        val backend = object : DriverBackend {
+            override fun launch(bundleId: String, clearState: Boolean, env: Map<String, String>) {}
+            override fun terminate(bundleId: String) {}
+            override fun tap(x: Int, y: Int) { taps.add(x to y) }
+            override fun tapSelector(selector: String) {}
+            override fun inputText(text: String) {}
+            override fun eraseText(characterCount: Int) {}
+            override fun swipe(fromX: Int, fromY: Int, toX: Int, toY: Int, durationMillis: Long) {}
+            override fun pressKey(key: String) {}
+            override fun longPress(x: Int, y: Int) {}
+            override fun screenshot(): Triple<ByteArray, Int, Int> = Triple(byteArrayOf(), 0, 0)
+            override fun hierarchy(): String = "{}"
+            override fun recentLogs(sinceUnixMillis: Long, minLevel: String): List<LogLine> = emptyList()
+            override fun waitForIdle(durationMillis: Long) {}
+            override fun healthy(): Boolean = true
+            override fun metrics(bundleId: String): MetricsSample = MetricsSample(0.0, 0L, 0L)
+        }
+        val client = newClient(backend)
+
+        client.doubleTap(Point.newBuilder().setX(120).setY(340).build())
+        assertEquals(listOf(120 to 340, 120 to 340), taps)
+    }
+
+    @Test fun eraseTextForwardsCharacterCount() {
+        val backend = StubDriverBackend("android")
+        val client = newClient(backend)
+
+        client.eraseText(EraseTextRequest.newBuilder().setCharacterCount(11).build())
+        assertEquals(11, backend.lastEraseCharacterCount)
+    }
+
     @Test fun screenshotReturnsBackendBytes() {
         val backend = object : DriverBackend by StubDriverBackend("android") {
             override fun screenshot(): Triple<ByteArray, Int, Int> = Triple(byteArrayOf(1, 2, 3), 1080, 2340)

sidecar/src/test/kotlin/dev/sanderling/sidecar/InputTextTest.kt

@@ -15,6 +15,18 @@ class InputTextTest {
         assertEquals(listOf(listOf("shell", "input", "text", "Emergency%sFund")), commands)
     }
 
+    @Test fun eraseTextSendsOneDeleteKeyPerCharacter() {
+        val commands = mutableListOf<List<String>>()
+        val backend = StubDriverBackend("android") { commands.add(it) }
+
+        backend.eraseText(3)
+
+        assertEquals(
+            List(3) { listOf("shell", "input", "keyevent", "KEYCODE_DEL") },
+            commands,
+        )
+    }
+
     @Test fun escapeForAdbInputTextSubstitutesSpaces() {
         assertEquals("hello%sworld", StubDriverBackend.escapeForAdbInputText("hello world"))
     }

sidecar/src/test/kotlin/dev/sanderling/sidecar/IosHierarchyTest.kt

@@ -0,0 +1,126 @@
+package dev.sanderling.sidecar
+
+import hierarchy.AXElement
+import hierarchy.AXFrame
+import org.junit.Test
+import kotlin.test.assertEquals
+
+class IosHierarchyTest {
+
+    private fun element(
+        elementType: Int,
+        label: String = "",
+        identifier: String = "",
+        title: String = "",
+        value: String = "",
+        placeholderValue: String = "",
+        children: ArrayList<AXElement> = arrayListOf(),
+    ) = AXElement(
+        label,
+        elementType,
+        identifier,
+        0,
+        0L,
+        0,
+        false,
+        0,
+        false,
+        placeholderValue,
+        value,
+        AXFrame(10f, 20f, 100f, 50f),
+        true,
+        title,
+        children,
+    )
+
+    @Test
+    fun buttonIsClickableNotEditable() {
+        val node = iosAxElementToTreeNode(element(elementType = 9, label = "Sign in", identifier = "LoginSubmit"))
+        assertEquals(true, node["clickable"])
+        assertEquals(false, node["editable"])
+        @Suppress("UNCHECKED_CAST")
+        val attributes = node["attributes"] as Map<String, String>
+        assertEquals("Button", attributes["class"])
+        assertEquals("LoginSubmit", attributes["resource-id"])
+        assertEquals("Sign in", attributes["accessibilityText"])
+    }
+
+    @Test
+    fun textFieldIsEditableNotClickable() {
+        val node = iosAxElementToTreeNode(element(elementType = 49, value = "[email protected]"))
+        assertEquals(false, node["clickable"])
+        assertEquals(true, node["editable"])
+        @Suppress("UNCHECKED_CAST")
+        val attributes = node["attributes"] as Map<String, String>
+        assertEquals("TextField", attributes["class"])
+        assertEquals("[email protected]", attributes["text"])
+        assertEquals("[email protected]", attributes["value"])
+    }
+
+    @Test
+    fun titleWinsOverValueForText() {
+        val node = iosAxElementToTreeNode(element(elementType = 48, title = "Heading", value = "ignored"))
+        @Suppress("UNCHECKED_CAST")
+        val attributes = node["attributes"] as Map<String, String>
+        assertEquals("Heading", attributes["text"])
+        assertEquals("StaticText", attributes["class"])
+    }
+
+    @Test
+    fun staticTextFallsBackToLabelForText() {
+        val node = iosAxElementToTreeNode(element(elementType = 48, label = "$1,234.00"))
+        @Suppress("UNCHECKED_CAST")
+        val attributes = node["attributes"] as Map<String, String>
+        assertEquals("$1,234.00", attributes["text"])
+    }
+
+    @Test
+    fun buttonFallsBackToLabelForText() {
+        val node = iosAxElementToTreeNode(element(elementType = 9, label = "Sign in"))
+        @Suppress("UNCHECKED_CAST")
+        val attributes = node["attributes"] as Map<String, String>
+        assertEquals("Sign in", attributes["text"])
+    }
+
+    @Test
+    fun emptyTextFieldDoesNotLeakLabelIntoText() {
+        val node = iosAxElementToTreeNode(element(elementType = 49, label = "Email"))
+        @Suppress("UNCHECKED_CAST")
+        val attributes = node["attributes"] as Map<String, String>
+        assertEquals("", attributes["text"])
+        assertEquals("Email", attributes["accessibilityText"])
+    }
+
+    @Test
+    fun switchOnIsChecked() {
+        val node = iosAxElementToTreeNode(element(elementType = 40, value = "1"))
+        assertEquals(true, node["checked"])
+        assertEquals(true, node["clickable"])
+    }
+
+    @Test
+    fun scrollViewIsScrollable() {
+        val node = iosAxElementToTreeNode(element(elementType = 46))
+        @Suppress("UNCHECKED_CAST")
+        val attributes = node["attributes"] as Map<String, String>
+        assertEquals("true", attributes["scrollable"])
+        assertEquals("ScrollView", attributes["class"])
+    }
+
+    @Test
+    fun childrenAreMappedRecursively() {
+        val child = element(elementType = 48, title = "Inner")
+        val node = iosAxElementToTreeNode(element(elementType = 1, children = arrayListOf(child)))
+        @Suppress("UNCHECKED_CAST")
+        val children = node["children"] as List<Map<String, Any?>>
+        assertEquals(1, children.size)
+        @Suppress("UNCHECKED_CAST")
+        val childAttributes = children[0]["attributes"] as Map<String, String>
+        assertEquals("Inner", childAttributes["text"])
+    }
+
+    @Test
+    fun unknownElementTypeFallsBackToOther() {
+        assertEquals("Other", iosElementTypeName(999))
+    }
+}

sidecar/src/test/kotlin/dev/sanderling/sidecar/SnapshotHandlerTest.kt

@@ -60,6 +60,7 @@ class SnapshotHandlerTest {
             override fun tap(x: Int, y: Int) {}
             override fun tapSelector(selector: String) {}
             override fun inputText(text: String) {}
+            override fun eraseText(characterCount: Int) {}
             override fun swipe(fromX: Int, fromY: Int, toX: Int, toY: Int, durationMillis: Long) {}
             override fun pressKey(key: String) {}
             override fun longPress(x: Int, y: Int) {}