fix(scroll): observe the movement a directional scroll can claim

src/daemon/__tests__/interaction-outcome-policy.test.ts

@@ -5,6 +5,7 @@ import {
   buildInteractionSurfaceSignature,
   classifyBaselineSurfaceEvidence,
   classifyInteractionSurfaceChange,
+  discriminatingSurfaceChangedWithinRect,
   markPendingInteractionOutcome,
   stripInternalInteractionFlags,
 } from '../interaction-outcome-policy.ts';
@@ -411,3 +412,58 @@ function makeSnapshotWithExtraText(label: string, y = 100): SnapshotState {
     ],
   };
 }
+
+// ---------------------------------------------------------------------------
+// discriminatingSurfaceChangedWithinRect (#2714 review): a whole-surface
+// difference that lives outside the region a command acted on is not that
+// command's doing. Measured on the Android tester, the status bar changed on
+// its own over a list that never moved. The strict key-matched view stays
+// owned here; this only narrows the region it is asked about.
+// ---------------------------------------------------------------------------
+
+const LIST_RECT = { x: 0, y: 150, width: 390, height: 600 };
+
+function rowAt(index: number, y: number) {
+  return {
+    type: 'StaticText',
+    identifier: `row-${index}`,
+    label: `Row ${index}`,
+    rect: { x: 12, y, width: 300, height: 24 },
+  } as SnapshotState['nodes'][number];
+}
+
+function surfaceWithClock(clock: string, secondRowY: number) {
+  return [
+    {
+      type: 'Image',
+      identifier: 'status-clock',
+      label: clock,
+      rect: { x: 12, y: 12, width: 40, height: 18 },
+    } as SnapshotState['nodes'][number],
+    rowAt(1, 200),
+    rowAt(2, secondRowY),
+  ];
+}
+
+test('discriminatingSurfaceChangedWithinRect reads a movement inside the region', () => {
+  const before = buildInteractionSurfaceSignature(surfaceWithClock('2:40', 300));
+  const after = buildInteractionSurfaceSignature(surfaceWithClock('2:40', 420));
+
+  assert.equal(discriminatingSurfaceChangedWithinRect(before, after, LIST_RECT), true);
+});
+
+test('discriminatingSurfaceChangedWithinRect does not read a movement outside the region', () => {
+  const before = buildInteractionSurfaceSignature(surfaceWithClock('2:40', 300));
+  const after = buildInteractionSurfaceSignature(surfaceWithClock('2:41', 300));
+
+  // The whole surface did change — that is the trap this reader exists to refuse.
+  assert.equal(classifyBaselineSurfaceEvidence(before, after), 'changed');
+  assert.equal(discriminatingSurfaceChangedWithinRect(before, after, LIST_RECT), false);
+});
+
+test('discriminatingSurfaceChangedWithinRect counts content appearing inside the region', () => {
+  const before = buildInteractionSurfaceSignature(surfaceWithClock('2:40', 300));
+  const after = buildInteractionSurfaceSignature([...surfaceWithClock('2:40', 300), rowAt(3, 640)]);
+
+  assert.equal(discriminatingSurfaceChangedWithinRect(before, after, LIST_RECT), true);
+});