fix(web): polish playlist edit-mode shift+click range selection

Two small correctness fixes on top of the existing row-click selection
in playlist edit mode.

- `EditAwareTracksTable` now resets its shift-key ref on `window` blur.
  Previously, holding Shift while Cmd/Alt-Tabbing away would leave the
  ref stuck true (the keyup fires in the other window), so the next
  click on return was interpreted as a shift-extend.
- `TrackSelectionContext.toggle` now keeps the anchor row stable across
  a sequence of shift-clicks. The anchor only moves on a plain click.
  This matches Finder / Gmail / Drive: click A, shift-click C selects
  A..C; a follow-up shift-click E then selects A..E (not C..E).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: dylanjeffers

packages/web/src/components/collection/desktop/edit-mode/tracks/EditAwareTracksTable.tsx

@@ -42,11 +42,18 @@ export const EditAwareTracksTable = (props: EditAwareTracksTableProps) => {
     const up = (e: KeyboardEvent) => {
       if (e.key === 'Shift') shiftRef.current = false
     }
+    // Without this, Cmd/Alt-Tabbing away while holding Shift leaves shiftRef
+    // stuck true because the keyup fires in the other window.
+    const reset = () => {
+      shiftRef.current = false
+    }
     window.addEventListener('keydown', down)
     window.addEventListener('keyup', up)
+    window.addEventListener('blur', reset)
     return () => {
       window.removeEventListener('keydown', down)
       window.removeEventListener('keyup', up)
+      window.removeEventListener('blur', reset)
     }
   }, [isEditingThis])
 

packages/web/src/components/collection/desktop/edit-mode/tracks/TrackSelectionContext.tsx

@@ -42,10 +42,13 @@ export const TrackSelectionProvider = ({
 
   const toggle = useCallback<SelectionContextValue['toggle']>(
     (id, index, opts) => {
+      const isShiftRange = !!opts?.shift && lastIndexRef.current !== null
       setSelectedState((prev) => {
         const next = new Set(prev)
-        if (opts?.shift && lastIndexRef.current !== null) {
-          const [a, b] = [lastIndexRef.current, index].sort((x, y) => x - y)
+        if (isShiftRange) {
+          const [a, b] = [lastIndexRef.current as number, index].sort(
+            (x, y) => x - y
+          )
           for (let i = a; i <= b; i += 1) {
             const sliceId = orderedIds[i]
             if (sliceId !== undefined) next.add(sliceId)
@@ -55,9 +58,13 @@ export const TrackSelectionProvider = ({
         } else {
           next.add(id)
         }
-        lastIndexRef.current = index
         return next
       })
+      // Keep the anchor stable across a shift-click sequence (matches
+      // Finder / Gmail / Drive). A plain click resets the anchor.
+      if (!isShiftRange) {
+        lastIndexRef.current = index
+      }
     },
     [orderedIds]
   )