refactor(web): extract range release resolution

apps/web/src/hooks/useTimelineDrag.ts

@@ -39,7 +39,8 @@ import {
 } from "./timelineMultiSelect.js";
 import { beginCanvasMultiSelectSession } from "./timelineMultiSelectSession.js";
 import { reconcileOptimisticEntries } from "./timelineOptimisticAllocations.js";
-import { createRangeSelectionState, finalizeRangeSelection, updateRangeSelectionDraft } from "./timelineRangeSelection.js";
+import { resolveRangeSelectionCancel, resolveRangeSelectionRelease } from "./timelineRangeRelease.js";
+import { createRangeSelectionState, updateRangeSelectionDraft } from "./timelineRangeSelection.js";
 import { type TouchCanvasPointerEvent, type TouchMouseDownEvent } from "./timelineTouchAdapters.js";
 
 const DRAG_CLICK_THRESHOLD_PX = 5;
@@ -716,14 +717,12 @@ export function useTimelineDrag({
       }
 
       // Range select
-      const range = rangeStateRef.current;
-      const selection = finalizeRangeSelection(range, e.clientX, e.clientY);
-      if (selection) {
-        onRangeSelected?.(selection);
+      const release = resolveRangeSelectionRelease(rangeStateRef.current, e.clientX, e.clientY, INITIAL_RANGE_STATE);
+      if (release.kind !== "complete") return;
 
-        rangeStateRef.current = INITIAL_RANGE_STATE;
-        setRangeState(INITIAL_RANGE_STATE);
-      }
+      onRangeSelected?.(release.selection);
+      rangeStateRef.current = release.nextState;
+      setRangeState(release.nextState);
     },
     [finalizeActiveProjectDrag, onRangeSelected],
   );
@@ -731,10 +730,11 @@ export function useTimelineDrag({
   const onCanvasMouseLeave = useCallback(() => {
     // Only cancel project-shift and range-select on canvas leave.
     // Alloc drag is managed by document-level listeners and must NOT be cancelled here.
-    if (rangeStateRef.current.isSelecting) {
-      rangeStateRef.current = INITIAL_RANGE_STATE;
-      setRangeState(INITIAL_RANGE_STATE);
-    }
+    const cancellation = resolveRangeSelectionCancel(rangeStateRef.current, INITIAL_RANGE_STATE);
+    if (!cancellation.didReset) return;
+
+    rangeStateRef.current = cancellation.nextState;
+    setRangeState(cancellation.nextState);
   }, []);
 
   // ── Multi-select (right-click drag) ─────────────────────────────────────────