fix(app): stabilize timeline scrolling during updates

Publish real virtual-row measurements while suppressing momentum-breaking scroll writes, then reconcile the reader anchor once scrolling settles. Keep live patches out of the timeline during active gestures and add Electron coverage for tall-row overlap, residual motion, and existing-message updates.
2026-07-17 02:05:22 +08:00
parent d9f31bbe8a
commit d399ab154f
5 changed files with 513 additions and 17 deletions
@@ -7,6 +7,7 @@ test('virtualizer scroll writes are discarded throughout a user scroll', () => {
  let scrolling = true;
  const element = { scrollTop: 100 };
  const writes = [];
+  const suppressed = [];
  const instance = { scrollElement: element };
  const policy = createSessionTimelineScrollPolicy({
    isUserScrolling: () => scrolling,
@@ -14,11 +15,19 @@ test('virtualizer scroll writes are discarded throughout a user scroll', () => {
      writes.push({ offset, ...options });
      element.scrollTop = offset + (options.adjustments || 0);
    },
+    onSuppressedAdjustment: (offset, options) => {
+      suppressed.push({ offset, ...options });
+    },
  });

  policy.scrollToFn(100, { behavior: 'auto', adjustments: 24 }, instance);
  policy.scrollToFn(124, { behavior: 'auto' }, instance);
  assert.deepEqual(writes, [], 'momentum is never interrupted by a programmatic write');
+  assert.deepEqual(
+    suppressed,
+    [{ offset: 100, behavior: 'auto', adjustments: 24 }],
+    'measurement adjustments are exposed for compositor compensation',
+  );

  scrolling = false;
  assert.equal(element.scrollTop, 100, 'scrollend never replays a suppressed correction');