fix desktop icon grid gap at right edge: stretch column pitch so right-anchored stacks sit flush

src/app/components/useDesktopIcons.ts

@@ -53,11 +53,20 @@ export function useDesktopIcons(
   const [positions, setPositions] = useState<Record<string, IconPosition>>({});
   const [dragId, setDragId] = useState<string | null>(null);
   const cellRef = useRef({ w: DEFAULT_CELL_WIDTH, h: DEFAULT_CELL_HEIGHT });
-  const gridRef = useRef<{ cols: number; rows: number; originX: number; originY: number }>({
+  const gridRef = useRef<{
+    cols: number;
+    rows: number;
+    originX: number;
+    originY: number;
+    pitchX: number;
+    pitchY: number;
+  }>({
     cols: 1,
     rows: 1,
     originX: 10,
     originY: 12,
+    pitchX: DEFAULT_CELL_WIDTH + GRID_GAP,
+    pitchY: DEFAULT_CELL_HEIGHT + GRID_GAP,
   });
   const suppressRef = useRef(false);
 
@@ -71,8 +80,10 @@ export function useDesktopIcons(
 
   /**
    * Work out the grid from where the launcher stacks actually sit. The icon
-   * width/height (plus the flex gap) is the cell pitch, and the left/top stack
-   * offsets give column 0 / row 0. Falls back to sensible values before mount.
+   * width/height is the cell size and the left/top stack offsets give column 0 /
+   * row 0; the column pitch is stretched a touch so the right-hand stacks stay
+   * flush with the right margin instead of stopping up to a cell short. Falls
+   * back to sensible values before mount.
    */
   const measure = useCallback(() => {
     const root = rootRef.current;
@@ -86,11 +97,13 @@ export function useDesktopIcons(
 
     // Each stack renders from its own top offset; the left stack defines row 0,
     // the top-right stack shares it and the bottom-right stack defines the last
-    // row band. Use the smallest top as the grid origin.
+    // row band. Use the smallest top as the grid origin. The right-anchored
+    // stacks also give the true right margin.
     let cellW = 0;
     let cellH = 0;
     let originX = Infinity;
     let originY = Infinity;
+    let rightMargin = Infinity;
 
     stacks.forEach((stack) => {
       const stackRect = stack.getBoundingClientRect();
@@ -109,45 +122,60 @@ export function useDesktopIcons(
         const r = el.getBoundingClientRect();
         cellW = Math.max(cellW, r.width);
         cellH = Math.max(cellH, r.height);
+        rightMargin = Math.min(rightMargin, rootRect.right - r.right);
       });
     });
 
     if (!Number.isFinite(originX)) originX = 10;
     if (!Number.isFinite(originY)) originY = 12;
+    if (!Number.isFinite(rightMargin)) rightMargin = 10;
     if (cellW <= 0 || cellH <= 0) return;
 
-    const pitchX = cellW + GRID_GAP;
     const pitchY = cellH + GRID_GAP;
     const width = root.clientWidth || window.innerWidth;
     const height = (root.clientHeight || window.innerHeight) - TASKBAR_HEIGHT;
 
+    // Columns tile from the left, but the services/friends stacks are anchored
+    // to the right edge. A fixed pitch leaves up to a full cell of slack on the
+    // right (the remainder of width / pitch), which pulled those icons away from
+    // the border. Stretch the column pitch a hair so the first and last columns
+    // land flush on both margins; the extra gap is a few px and stays uniform.
+    const minPitchX = cellW + GRID_GAP;
+    const span = width - originX - rightMargin;
+    const cols = Math.max(1, Math.floor((span + GRID_GAP) / minPitchX));
+    let pitchX = minPitchX;
+    if (cols > 1) {
+      const stretched = (span - cellW) / (cols - 1);
+      if (stretched > pitchX) pitchX = stretched;
+    }
+
     cellRef.current = { w: cellW, h: cellH };
     gridRef.current = {
-      cols: Math.max(1, Math.floor((width - originX) / pitchX)),
+      cols,
       rows: Math.max(1, Math.floor((height - originY) / pitchY)),
       originX,
       originY,
+      pitchX,
+      pitchY,
     };
   }, [rootRef]);
 
   const posToCell = useCallback(
     (p: IconPosition): Cell => {
-      const { w: cellW, h: cellH } = cellRef.current;
       const g = gridRef.current;
       return clampCell(
-        Math.round((p.x - g.originX) / (cellW + GRID_GAP)),
-        Math.round((p.y - g.originY) / (cellH + GRID_GAP))
+        Math.round((p.x - g.originX) / g.pitchX),
+        Math.round((p.y - g.originY) / g.pitchY)
       );
     },
     [clampCell]
   );
 
   const cellToPos = useCallback((c: Cell): IconPosition => {
-    const { w: cellW, h: cellH } = cellRef.current;
     const g = gridRef.current;
     return {
-      x: g.originX + c.col * (cellW + GRID_GAP),
-      y: g.originY + c.row * (cellH + GRID_GAP),
+      x: g.originX + c.col * g.pitchX,
+      y: g.originY + c.row * g.pitchY,
     };
   }, []);
 
@@ -217,7 +245,6 @@ export function useDesktopIcons(
   const defaultCells = useCallback(
     (keys: string[]): Record<string, IconPosition> => {
       const root = rootRef.current;
-      const { w: cellW, h: cellH } = cellRef.current;
       const g = gridRef.current;
       const out: Record<string, IconPosition> = {};
       if (!root) return out;
@@ -225,8 +252,8 @@ export function useDesktopIcons(
       const stacks = Array.from(
         root.querySelectorAll<HTMLElement>(".win-icons")
       ).filter((el) => el.querySelector("[data-drag-id]"));
-      const pitchX = cellW + GRID_GAP;
-      const pitchY = cellH + GRID_GAP;
+      const pitchX = g.pitchX;
+      const pitchY = g.pitchY;
       const rootRect = root.getBoundingClientRect();
 
       // Natural cell for each icon: the one its stack actually renders it in.
@@ -267,8 +294,8 @@ export function useDesktopIcons(
       const { w: cellW, h: cellH } = cellRef.current;
       const g = gridRef.current;
       return clampCell(
-        Math.floor((x - g.originX + GRID_GAP / 2) / (cellW + GRID_GAP)),
-        Math.floor((y - g.originY + GRID_GAP / 2) / (cellH + GRID_GAP))
+        Math.floor((x - g.originX + (g.pitchX - cellW) / 2) / g.pitchX),
+        Math.floor((y - g.originY + (g.pitchY - cellH) / 2) / g.pitchY)
       );
     },
     [clampCell]