@@ -1,6 +1,9 @@
 import assert from 'node:assert/strict';
 import { test } from 'vitest';
-import { listMcpExposedCommandNames } from '../../core/command-descriptor/registry.ts';
+import {
+  listCommandResponseDataTransforms,
+  listMcpExposedCommandNames,
+} from '../../core/command-descriptor/registry.ts';
 import {
   listCommandMetadata,
   listCommandMetadataNames,
@@ -49,6 +52,25 @@ test('common command input accepts web platform selector', () => {
   assert.equal(input.platform, 'web');
 });
 
+test('command response data transforms reference command input fields', () => {
+  const metadataByName = new Map<string, ReturnType<typeof listCommandMetadata>[number]>(
+    listCommandMetadata().map((metadata) => [metadata.name, metadata] as const),
+  );
+
+  for (const { command, transform } of listCommandResponseDataTransforms()) {
+    const metadata = metadataByName.get(command);
+    assert.ok(metadata, `${command} response data transform must have command metadata`);
+
+    const inputFields = new Set(Object.keys(metadata.inputSchema.properties ?? {}));
+    for (const field of Object.keys(transform.fields)) {
+      assert.ok(
+        inputFields.has(field),
+        `${command} response data transform field ${field} must be declared by command input metadata`,
+      );
+    }
+  }
+});
+
 test('command family facets expose one complete metadata and executable surface', () => {
   const familyNames = commandFamilies.map((family) => family.name);
   assert.deepEqual(familyNames, [...new Set(familyNames)], 'command family names must be unique');
 
@@ -141,7 +141,6 @@ const TOUCH_INTERACTION_RESPONSE_DATA_TRANSFORM = {
 
 const FILL_INTERACTION_RESPONSE_DATA_TRANSFORM = {
   fields: {
-    ...TOUCH_INTERACTION_RESPONSE_DATA_TRANSFORM.fields,
     delayMs: { defaultValue: 0 },
   },
 } as const satisfies CommandResponseDataTransform;
@@ -840,3 +839,23 @@ export function resolveCommandResponseDataTransform(
   if (command === undefined) return undefined;
   return RESPONSE_DATA_TRANSFORM_BY_COMMAND.get(command);
 }
+
+export function listCommandResponseDataTransforms(): Array<{
+  command: string;
+  transform: CommandResponseDataTransform;
+}> {
+  return Array.from(RESPONSE_DATA_TRANSFORM_BY_COMMAND, ([command, transform]) => ({
+    command,
+    transform,
+  }));
+}
+
+export function listCommandResponseDataTransformFieldNames(): string[] {
+  return [
+    ...new Set(
+      Array.from(RESPONSE_DATA_TRANSFORM_BY_COMMAND.values()).flatMap((transform) =>
+        Object.keys(transform.fields),
+      ),
+    ),
+  ].sort();
+}
@@ -1,8 +1,13 @@
-import { resolveCommandResponseDataTransform } from './command-descriptor/registry.ts';
+import {
+  listCommandResponseDataTransformFieldNames,
+  resolveCommandResponseDataTransform,
+} from './command-descriptor/registry.ts';
 import type { ResponseDataFieldTransform } from './command-descriptor/types.ts';
 
 export type InteractionResponseDataTransformCommand = 'click' | 'press' | 'fill';
 
+const controlledResponseDataFieldNames = new Set(listCommandResponseDataTransformFieldNames());
+
 export function transformInteractionResponseData(params: {
   command: InteractionResponseDataTransformCommand;
   input: Record<string, unknown> | undefined;
@@ -12,6 +17,7 @@ export function transformInteractionResponseData(params: {
     fields: readCommandResponseDataTransformFields(params.command),
     input: params.input ?? {},
     data: params.data,
+    controlledFields: controlledResponseDataFieldNames,
   });
 }
 
@@ -29,8 +35,11 @@ function applyResponseDataFieldTransforms(params: {
   fields: Record<string, ResponseDataFieldTransform>;
   input: Record<string, unknown>;
   data: Record<string, unknown> | undefined;
+  controlledFields: ReadonlySet<string>;
 }): Record<string, unknown> {
-  const transformed = { ...(params.data ?? {}) };
+  const transformed = Object.fromEntries(
+    Object.entries(params.data ?? {}).filter(([key]) => !params.controlledFields.has(key)),
+  );
   for (const [key, field] of Object.entries(params.fields)) {
     const value = params.input[key] === undefined ? field.defaultValue : params.input[key];
     if (value === undefined || (field.omitDefault === true && value === field.defaultValue)) {