diff --git a/lib/editor/canvas/pen_interactive_viewer.dart b/lib/editor/canvas/pen_interactive_viewer.dart
index 52d7c40..4c60988 100644
--- a/lib/editor/canvas/pen_interactive_viewer.dart
+++ b/lib/editor/canvas/pen_interactive_viewer.dart
@@ -194,13 +194,20 @@ class _PenInteractiveViewerState extends State<PenInteractiveViewer>
     // The transitional frame itself is skipped.
     if (details.pointerCount != _lastPointerCount) {
       _lastPointerCount = details.pointerCount;
-      _scaleStart = _transformer.value.getMaxScaleOnAxis();
+      // Anchor the new baseline to the CLEAN tracked scale (_lastAppliedScale),
+      // NOT a fresh matrix read-back. Windows touch flickers the pointer count
+      // (2↔1↔2) mid-pinch, firing this re-baseline spuriously; reading
+      // getMaxScaleOnAxis() at that glitchy instant popped _scaleStart to a
+      // noisy value, so the absolute map K = scaleStart / rawScaleAtBaseline
+      // oscillated frame-to-frame (the reported "zoom jump"). Using
+      // _lastAppliedScale makes the displayed scale CONTINUOUS across the
+      // re-baseline: target == _lastAppliedScale at this instant, regardless of
+      // any transient in the live matrix.
+      _scaleStart = _lastAppliedScale;
       _referenceFocalPoint = _transformer.toScene(details.localFocalPoint);
       _lastRawScale = details.scale;
-      _lastAppliedScale = _scaleStart!;
-      // Re-anchor the absolute mapping: from here, cumulative scale is measured
-      // relative to THIS frame's details.scale (so the next good frame starts
-      // from _scaleStart, not _scaleStart * a stale cumulative value).
+      // Re-anchor the cumulative scale to THIS frame's details.scale so the next
+      // good frame resumes from _scaleStart (not _scaleStart × a stale ratio).
       _rawScaleAtBaseline = details.scale;
       InputDiagnostics.instance.recordRebaseline();
       return;