SD-2541 - fix: avoid scrolling back when dragging selection

packages/super-editor/src/editors/v1/core/presentation-editor/PresentationEditor.ts

@@ -333,6 +333,8 @@ export class PresentationEditor extends EventEmitter {
   /**
    * When true, the next selection render scrolls the caret/selection head into view.
    * Only set for user-initiated actions (keyboard/mouse selection, image click, zoom).
+   * Not set on each `selectionUpdate` while a pointer drag is active — edge auto-scroll
+   * owns the viewport then; `notifyDragSelectionEnded` restores one scroll after mouseup.
    * Passive re-renders (virtualization remounts, layout completions, DOM rebuilds) leave
    * this unset so they don't fight the user's scroll position.
    */
@@ -3245,8 +3247,11 @@ export class PresentationEditor extends EventEmitter {
       }
     };
     const handleSelection = () => {
-      // User-initiated selection change (keyboard, mouse) — scroll caret into view.
-      this.#shouldScrollSelectionIntoView = true;
+      // User-initiated selection change — scroll caret/head into view once, except during
+      // pointer drag: EditorInputManager edge auto-scroll must not fight #scrollActiveEndIntoView.
+      if (!this.#editorInputManager?.isDragging) {
+        this.#shouldScrollSelectionIntoView = true;
+      }
       // Use immediate rendering for selection-only changes (clicks, arrow keys).
       // Without immediate, the render is RAF-deferred — leaving a window where
       // a remote collaborator's edit can cancel the pending render via
@@ -3566,6 +3571,10 @@ export class PresentationEditor extends EventEmitter {
       selectParagraphAt: (pos: number) => this.#selectParagraphAt(pos),
       finalizeDragSelectionWithDom: (pointer, dragAnchor, dragMode) =>
         this.#finalizeDragSelectionWithDom(pointer, dragAnchor, dragMode),
+      notifyDragSelectionEnded: () => {
+        this.#shouldScrollSelectionIntoView = true;
+        this.#scheduleSelectionUpdate({ immediate: true });
+      },
       hitTestTable: (x: number, y: number) => this.#hitTestTable(x, y),
     });
   }
@@ -4990,7 +4999,8 @@ export class PresentationEditor extends EventEmitter {
     // (virtualization remounts, layout completions) never set this flag, so
     // they won't scroll the viewport to the caret — only real user-initiated
     // selection changes (keyboard, mouse, image click, zoom) will.
-    const shouldScrollIntoView = this.#shouldScrollSelectionIntoView;
+    // Belt-and-suspenders: never scroll from this path while pointer-drag is active.
+    const shouldScrollIntoView = this.#shouldScrollSelectionIntoView && !this.#editorInputManager?.isDragging;
     this.#shouldScrollSelectionIntoView = false;
 
     const sessionMode = this.#headerFooterSession?.session?.mode ?? 'body';

packages/super-editor/src/editors/v1/core/presentation-editor/pointer-events/EditorInputManager.ts

@@ -354,6 +354,12 @@ export type EditorInputCallbacks = {
     dragAnchor: number,
     dragMode: 'char' | 'word' | 'para',
   ) => void;
+  /**
+   * Called when a pointer text-drag selection ends.
+   * Used to scroll the selection into view once after auto-scroll stops; during drag,
+   * selection-driven scroll is suppressed to avoid fighting edge auto-scroll.
+   */
+  notifyDragSelectionEnded?: () => void;
   /** Hit test table at coordinates */
   hitTestTable?: (x: number, y: number) => TableHitResult | null;
 };
@@ -1379,6 +1385,8 @@ export class EditorInputManager {
         this.#callbacks.finalizeDragSelectionWithDom?.(pointer, dragAnchor, dragMode);
       }
 
+      this.#callbacks.notifyDragSelectionEnded?.();
+
       this.#callbacks.scheduleA11ySelectionAnnouncement?.({ immediate: true });
 
       this.#dragLastPointer = null;

packages/super-editor/src/editors/v1/core/presentation-editor/tests/EditorInputManager.dragAutoScroll.test.ts

@@ -135,6 +135,7 @@ describe('EditorInputManager - Drag Auto Scroll', () => {
       normalizeClientPoint: vi.fn((clientX: number, clientY: number) => ({ x: clientX, y: clientY })),
       updateSelectionVirtualizationPins: vi.fn(),
       scheduleSelectionUpdate: vi.fn(),
+      notifyDragSelectionEnded: vi.fn(),
     };
 
     manager = new EditorInputManager();
@@ -254,6 +255,8 @@ describe('EditorInputManager - Drag Auto Scroll', () => {
 
     // Auto-scroll should be stopped
     expect(rafCallback).toBeNull();
+    // one post-drag hook so PresentationEditor can scroll selection into view after auto-scroll stops
+    expect(mockCallbacks.notifyDragSelectionEnded).toHaveBeenCalledTimes(1);
   });
 
   it('does not auto-scroll in header/footer mode', () => {
@@ -328,4 +331,41 @@ describe('EditorInputManager - Drag Auto Scroll', () => {
       expect(scrollContainer.scrollLeft).toBe(0);
     });
   });
+
+  describe('notifyDragSelectionEnded (selection scroll after drag)', () => {
+    it('invokes notifyDragSelectionEnded exactly once when a text drag ends after movement', () => {
+      startDrag(10, 10);
+      moveDrag(40, 25);
+      endDrag(40, 25);
+
+      expect(mockCallbacks.notifyDragSelectionEnded).toHaveBeenCalledTimes(1);
+    });
+
+    it('invokes notifyDragSelectionEnded when pointer goes down and up without move (click-hold-release)', () => {
+      startDrag(10, 10);
+      endDrag(10, 10);
+
+      expect(mockCallbacks.notifyDragSelectionEnded).toHaveBeenCalledTimes(1);
+    });
+
+    it('does not invoke notifyDragSelectionEnded on pointer up if no drag was started', () => {
+      endDrag(10, 10);
+
+      expect(mockCallbacks.notifyDragSelectionEnded).not.toHaveBeenCalled();
+    });
+
+    it('invokes notifyDragSelectionEnded once per completed drag gesture', () => {
+      startDrag(10, 10);
+      moveDrag(20, 15);
+      endDrag(20, 15);
+      expect(mockCallbacks.notifyDragSelectionEnded).toHaveBeenCalledTimes(1);
+
+      (mockCallbacks.notifyDragSelectionEnded as ReturnType<typeof vi.fn>).mockClear();
+
+      startDrag(50, 50);
+      moveDrag(60, 55);
+      endDrag(60, 55);
+      expect(mockCallbacks.notifyDragSelectionEnded).toHaveBeenCalledTimes(1);
+    });
+  });
 });