diff --git a/src/TrackLabConstants.ts b/src/TrackLabConstants.ts
index 8294c04..1e958d4 100644
--- a/src/TrackLabConstants.ts
+++ b/src/TrackLabConstants.ts
@@ -97,3 +97,8 @@ export const CONTROL_ICON_SIZE = 20;
 export const CONTROL_PANEL_ROWS_SPACING = 12;
 export const CONTROL_PANEL_X_MARGIN = 12;
 export const CONTROL_PANEL_Y_MARGIN = 12;
+
+// ── Graph zoom ─────────────────────────────────────────────────────────────
+// Multiplicative zoom step applied by wheel ticks and the zoom-in/zoom-out
+// buttons on the configurable graph. A value of 1.1 zooms by 10% per step.
+export const GRAPH_ZOOM_FACTOR = 1.1;
diff --git a/src/screen-name/graph/AxisGestureHandler.ts b/src/screen-name/graph/AxisGestureHandler.ts
index 50541ef..08bb094 100644
--- a/src/screen-name/graph/AxisGestureHandler.ts
+++ b/src/screen-name/graph/AxisGestureHandler.ts
@@ -17,6 +17,7 @@
 import type { ChartRectangle, ChartTransform } from "scenerystack/bamboo";
 import { Range, Vector2 } from "scenerystack/dot";
 import { DragListener, type Pointer, type Rectangle } from "scenerystack/scenery";
+import { GRAPH_ZOOM_FACTOR } from "../../TrackLabConstants.js";
 import trackLab from "../../TrackLabNamespace.js";
 import type GraphDataManager from "./GraphDataManager.js";
 import type { ChartConfig, GraphDimensions } from "./GraphInteractionHandler.js";
@@ -39,8 +40,6 @@ export default class AxisGestureHandler {
   private graphWidth: number;
   private graphHeight: number;
 
-  private readonly zoomFactor: number = 1.1;
-
   public constructor(chartConfig: ChartConfig, regions: AxisInteractionRegions, dimensions: GraphDimensions) {
     this.chartTransform = chartConfig.chartTransform;
     this.chartRectangle = chartConfig.chartRectangle;
@@ -77,14 +76,13 @@ export default class AxisGestureHandler {
     // Read the current model range for this axis.
     const getRange = (): Range => (isX ? this.chartTransform.modelXRange : this.chartTransform.modelYRange);
 
-    // Apply a new range for this axis and update tick spacing.
+    // Apply a new range for this axis via the data manager (sets isManuallyZoomed,
+    // updates chartTransform, and updates tick spacing atomically).
     const setRange = (range: Range): void => {
       if (isX) {
-        this.chartTransform.setModelXRange(range);
-        this.dataManager.updateTickSpacing(range, this.chartTransform.modelYRange);
+        this.dataManager.setRange(range, this.chartTransform.modelYRange);
       } else {
-        this.chartTransform.setModelYRange(range);
-        this.dataManager.updateTickSpacing(this.chartTransform.modelXRange, range);
+        this.dataManager.setRange(this.chartTransform.modelXRange, range);
       }
     };
 
@@ -125,7 +123,6 @@ export default class AxisGestureHandler {
         if (activePointers.size === 1) {
           singleTouchStart = coord(pt);
           initialRange = getRange().copy();
-          this.dataManager.setManuallyZoomed(true);
         } else if (activePointers.size === 2) {
           const points = Array.from(activePointers.values());
           const p0 = points[0];
@@ -135,7 +132,6 @@ export default class AxisGestureHandler {
             initialPinchMidpoint = (coord(p0) + coord(p1)) / 2;
             initialRange = getRange().copy();
             singleTouchStart = null;
-            this.dataManager.setManuallyZoomed(true);
           }
         }
       },
@@ -229,7 +225,6 @@ export default class AxisGestureHandler {
       start: (event) => {
         mouseDragStart = coord(event.pointer.point);
         mouseDragInitialRange = getRange().copy();
-        this.dataManager.setManuallyZoomed(true);
       },
 
       drag: (event) => {
@@ -278,7 +273,7 @@ export default class AxisGestureHandler {
         const modelCenter = isX ? modelPos.x : modelPos.y;
 
         const currentRange = getRange();
-        const zoomFactor = delta < 0 ? this.zoomFactor : 1 / this.zoomFactor;
+        const zoomFactor = delta < 0 ? GRAPH_ZOOM_FACTOR : 1 / GRAPH_ZOOM_FACTOR;
 
         setRange(
           new Range(
@@ -286,7 +281,6 @@ export default class AxisGestureHandler {
             modelCenter + (currentRange.max - modelCenter) / zoomFactor,
           ),
         );
-        this.dataManager.setManuallyZoomed(true);
       },
     });
   }
diff --git a/src/screen-name/graph/GraphDataManager.ts b/src/screen-name/graph/GraphDataManager.ts
index b8bf1c3..fe2fea7 100644
--- a/src/screen-name/graph/GraphDataManager.ts
+++ b/src/screen-name/graph/GraphDataManager.ts
@@ -319,6 +319,21 @@ export default class GraphDataManager {
     return Math.max(spacing, rangeLength / 20);
   }
 
+  /**
+   * Apply a new x/y range to the chart, mark the view as manually zoomed, and
+   * update tick spacing — all in one atomic call.
+   *
+   * All gesture handlers should use this method instead of mutating
+   * chartTransform directly, so that range validation and the manually-zoomed
+   * flag are always applied together.
+   */
+  public setRange(xRange: Range, yRange: Range): void {
+    this.isManuallyZoomed = true;
+    this.chartTransform.setModelXRange(xRange);
+    this.chartTransform.setModelYRange(yRange);
+    this.updateTickSpacing(xRange, yRange);
+  }
+
   /**
    * Set the manually zoomed flag (called by interaction handlers)
    */
diff --git a/src/screen-name/graph/PanGestureHandler.ts b/src/screen-name/graph/PanGestureHandler.ts
index 8c98993..7c026a1 100644
--- a/src/screen-name/graph/PanGestureHandler.ts
+++ b/src/screen-name/graph/PanGestureHandler.ts
@@ -61,9 +61,7 @@ export default class PanGestureHandler {
         break;
     }
 
-    this.chartTransform.setModelXRange(newXRange);
-    this.chartTransform.setModelYRange(newYRange);
-    this.dataManager.updateTickSpacing(newXRange, newYRange);
+    this.dataManager.setRange(newXRange, newYRange);
   }
 
   // ── Private setup helpers ──────────────────────────────────────────────────
@@ -79,9 +77,6 @@ export default class PanGestureHandler {
         dragStartModelPoint = this.chartTransform.viewToModelPosition(viewPoint);
         dragStartXRange = this.chartTransform.modelXRange.copy();
         dragStartYRange = this.chartTransform.modelYRange.copy();
-
-        // Suppress auto-scaling while the user is panning
-        this.dataManager.setManuallyZoomed(true);
       },
 
       drag: (event) => {
@@ -98,9 +93,7 @@ export default class PanGestureHandler {
         const newXRange = new Range(dragStartXRange.min + deltaX, dragStartXRange.max + deltaX);
         const newYRange = new Range(dragStartYRange.min + deltaY, dragStartYRange.max + deltaY);
 
-        this.chartTransform.setModelXRange(newXRange);
-        this.chartTransform.setModelYRange(newYRange);
-        this.dataManager.updateTickSpacing(newXRange, newYRange);
+        this.dataManager.setRange(newXRange, newYRange);
       },
 
       end: () => {
diff --git a/src/screen-name/graph/ZoomGestureHandler.ts b/src/screen-name/graph/ZoomGestureHandler.ts
index 20c41ca..996452c 100644
--- a/src/screen-name/graph/ZoomGestureHandler.ts
+++ b/src/screen-name/graph/ZoomGestureHandler.ts
@@ -9,6 +9,7 @@
 import type { ChartRectangle, ChartTransform } from "scenerystack/bamboo";
 import { Range, Vector2 } from "scenerystack/dot";
 import type { Pointer } from "scenerystack/scenery";
+import { GRAPH_ZOOM_FACTOR } from "../../TrackLabConstants.js";
 import trackLab from "../../TrackLabNamespace.js";
 import type GraphDataManager from "./GraphDataManager.js";
 import type { ChartConfig, GraphDimensions } from "./GraphInteractionHandler.js";
@@ -17,7 +18,6 @@ export default class ZoomGestureHandler {
   private readonly chartTransform: ChartTransform;
   private readonly chartRectangle: ChartRectangle;
   private readonly dataManager: GraphDataManager;
-  private readonly zoomFactor: number = 1.1; // 10% zoom per wheel tick
 
   private graphWidth: number;
   private graphHeight: number;
@@ -58,7 +58,7 @@ export default class ZoomGestureHandler {
    */
   public zoomIn(): void {
     const center = new Vector2(this.graphWidth / 2, this.graphHeight / 2);
-    this.zoom(this.zoomFactor, center, true);
+    this.zoom(GRAPH_ZOOM_FACTOR, center);
   }
 
   /**
@@ -66,7 +66,7 @@ export default class ZoomGestureHandler {
    */
   public zoomOut(): void {
     const center = new Vector2(this.graphWidth / 2, this.graphHeight / 2);
-    this.zoom(1 / this.zoomFactor, center, true);
+    this.zoom(1 / GRAPH_ZOOM_FACTOR, center);
   }
 
   // ── Private setup helpers ──────────────────────────────────────────────────
@@ -79,9 +79,9 @@ export default class ZoomGestureHandler {
         const pointerPoint = this.chartRectangle.globalToLocalPoint(event.pointer.point);
 
         if (delta < 0) {
-          this.zoom(this.zoomFactor, pointerPoint);
+          this.zoom(GRAPH_ZOOM_FACTOR, pointerPoint);
         } else {
-          this.zoom(1 / this.zoomFactor, pointerPoint);
+          this.zoom(1 / GRAPH_ZOOM_FACTOR, pointerPoint);
         }
       },
     });
@@ -122,7 +122,6 @@ export default class ZoomGestureHandler {
             initialMidpoint = point0.average(point1);
             initialXRange = this.chartTransform.modelXRange.copy();
             initialYRange = this.chartTransform.modelYRange.copy();
-            this.dataManager.setManuallyZoomed(true);
           }
         }
       },
@@ -152,9 +151,7 @@ export default class ZoomGestureHandler {
           const yMin = initialModelCenter.y - (initialModelCenter.y - initialYRange.min) * zoomFactor;
           const yMax = initialModelCenter.y + (initialYRange.max - initialModelCenter.y) * zoomFactor;
 
-          this.chartTransform.setModelXRange(new Range(xMin, xMax));
-          this.chartTransform.setModelYRange(new Range(yMin, yMax));
-          this.dataManager.updateTickSpacing(this.chartTransform.modelXRange, this.chartTransform.modelYRange);
+          this.dataManager.setRange(new Range(xMin, xMax), new Range(yMin, yMax));
         }
       },
 
@@ -193,13 +190,8 @@ export default class ZoomGestureHandler {
    *
    * @param factor - >1 zooms in, <1 zooms out
    * @param centerPoint - Zoom anchor in local view coordinates
-   * @param setManualFlag - When true, suppresses subsequent auto-rescaling
    */
-  public zoom(factor: number, centerPoint: Vector2, setManualFlag: boolean = true): void {
-    if (setManualFlag) {
-      this.dataManager.setManuallyZoomed(true);
-    }
-
+  public zoom(factor: number, centerPoint: Vector2): void {
     const currentXRange = this.chartTransform.modelXRange;
     const currentYRange = this.chartTransform.modelYRange;
     const modelCenter = this.chartTransform.viewToModelPosition(centerPoint);
@@ -209,12 +201,7 @@ export default class ZoomGestureHandler {
     const yMin = modelCenter.y - (modelCenter.y - currentYRange.min) / factor;
     const yMax = modelCenter.y + (currentYRange.max - modelCenter.y) / factor;
 
-    const newXRange = new Range(xMin, xMax);
-    const newYRange = new Range(yMin, yMax);
-
-    this.chartTransform.setModelXRange(newXRange);
-    this.chartTransform.setModelYRange(newYRange);
-    this.dataManager.updateTickSpacing(newXRange, newYRange);
+    this.dataManager.setRange(new Range(xMin, xMax), new Range(yMin, yMax));
   }
 
   private resetZoom(): void {
diff --git a/src/screen-name/model/SimModel.ts b/src/screen-name/model/SimModel.ts
index 89ee080..3594d4b 100644
--- a/src/screen-name/model/SimModel.ts
+++ b/src/screen-name/model/SimModel.ts
@@ -56,6 +56,20 @@ export class SimModel {
     return this.overlayTools.modelViewTransformProperty.value.inversePosition2(pixelPoint);
   }
 
+  /**
+   * Record a digitized point on the given track at the current playback position.
+   *
+   * The view passes raw inputs (track id + pixel position); this method
+   * coordinates all sub-model interactions so the view does not need to reach
+   * into playback or overlayTools directly.
+   */
+  public recordTrackPoint(trackId: string, pixelPoint: Vector2): void {
+    const time = this.playback.currentTimeProperty.value;
+    const frame = Math.round(time * this.playback.frameRateProperty.value);
+    const modelPt = this.overlayTools.modelViewTransformProperty.value.inversePosition2(pixelPoint);
+    this.tracking.addPointToTrack(trackId, frame, time, modelPt.x, modelPt.y);
+  }
+
   // ── Video source activation ─────────────────────────────────────────────
   // Each method sets all affected sub-model properties atomically so that no
   // intermediate state is visible to subscribers.
diff --git a/src/screen-name/view/DigitizingOverlayNode.ts b/src/screen-name/view/DigitizingOverlayNode.ts
index 1c5462d..b24f897 100644
--- a/src/screen-name/view/DigitizingOverlayNode.ts
+++ b/src/screen-name/view/DigitizingOverlayNode.ts
@@ -23,6 +23,8 @@ type DigitizingOverlayNodeOptions = {
   playback: VideoPlaybackModel;
   magnifyVideoProperty: TReadOnlyProperty<boolean>;
   modelViewTransformProperty: TReadOnlyProperty<Transform3>;
+  /** Record a digitized point on the given track at the given pixel position. */
+  recordPoint: (trackId: string, pixelPoint: Vector2) => void;
 };
 
 const OUTER_R = 20;
@@ -390,12 +392,7 @@ export class DigitizingOverlayNode extends Node {
           const rawLocalPt = digitizingOverlay.globalToLocalPoint(event.pointer.point);
           const localPt = event.pointer.type === "touch" ? rawLocalPt.plusXY(0, -TOUCH_CURSOR_OFFSET_Y) : rawLocalPt;
 
-          const time = playback.currentTimeProperty.value;
-          const frame = Math.round(time * playback.frameRateProperty.value);
-
-          const modelPt = modelViewTransformProperty.value.inversePosition2(localPt);
-
-          tracking.addPointToTrack(activeId, frame, time, modelPt.x, modelPt.y);
+          options.recordPoint(activeId, localPt);
           onPointAdded();
         },
         tandem: Tandem.OPT_OUT,
diff --git a/src/screen-name/view/VideoPlayerNode.ts b/src/screen-name/view/VideoPlayerNode.ts
index 8987af1..861cd97 100644
--- a/src/screen-name/view/VideoPlayerNode.ts
+++ b/src/screen-name/view/VideoPlayerNode.ts
@@ -144,6 +144,7 @@ export class VideoPlayerNode extends Node {
         playback: model.playback,
         magnifyVideoProperty: model.overlayTools.magnifyVideoProperty,
         modelViewTransformProperty: model.overlayTools.modelViewTransformProperty,
+        recordPoint: (trackId, pixelPoint) => model.recordTrackPoint(trackId, pixelPoint),
       },
       () => this.stepForward(),
     );