Merge pull request 'fix: restore saved gridstack layout faithfully (#13)' (#15) from ai/issue-13-persist-layout into main

Reviewed-on: #15
Reviewed-by: pitfriedrich <bp.webservice@gmail.com>

src/main/frontend/components/grid-stack.ts

@@ -20,7 +20,12 @@ class GridStackLayout extends HTMLElement {
     disconnectedCallback() {
         this.observer?.disconnect();
         this.observer = undefined;
-        clearTimeout(this.persistTimer);
+        // Write out a still-pending debounced save instead of dropping it:
+        // a drag/resize followed straight away by navigating to another route
+        // detaches this element inside the debounce window, which used to lose
+        // the very last layout change. The server is not notified — its view is
+        // going away with us.
+        this.flushPersist();
         this.grid?.destroy(false); // keep DOM — Flow owns the children
         this.grid = undefined;
     }
@@ -99,16 +104,28 @@ class GridStackLayout extends HTMLElement {
 
     private schedulePersist() {
         clearTimeout(this.persistTimer);
-        this.persistTimer = setTimeout(() => this.persist(), 150);
+        this.persistTimer = setTimeout(() => {
+            this.persistTimer = undefined;
+            this.persist();
+        }, 150);
     }
 
-    private persist() {
+    private flushPersist() {
+        if (this.persistTimer === undefined) return;
+        clearTimeout(this.persistTimer);
+        this.persistTimer = undefined;
+        this.persist(false);
+    }
+
+    private persist(notifyServer = true) {
         if (!this.grid) return;
         const nodes = this.grid.save(false) as GridStackNode[];
         if (this.storageKey) {
             localStorage.setItem(STORAGE_PREFIX + this.storageKey, JSON.stringify(nodes));
         }
-        (this as any).$server?.onLayoutChange(JSON.stringify(nodes));
+        if (notifyServer) {
+            (this as any).$server?.onLayoutChange(JSON.stringify(nodes));
+        }
     }
 
     private restore() {
@@ -122,13 +139,22 @@ class GridStackLayout extends HTMLElement {
         } catch {
             return;
         }
+        if (!Array.isArray(nodes)) return;
 
-        for (const node of nodes) {
-            if (!node.id) continue;
-            const el = this.querySelector(`:scope > [gs-id="${node.id}"]`) as HTMLElement | null;
-            if (!el) continue; // item no longer present server-side — skip, degrade gracefully
-            this.grid.update(el, { x: node.x, y: node.y, w: node.w, h: node.h });
-        }
+        // Items dropped server-side since the layout was saved are skipped, so a
+        // stale entry degrades gracefully instead of blocking the restore.
+        const known = nodes.filter((node) => node.id
+                && this.querySelector(`:scope > [gs-id="${CSS.escape(String(node.id))}"]`));
+        if (!known.length) return;
+
+        // load() rather than a per-item update() loop: it sorts the saved nodes,
+        // pulls them out of the engine before re-placing them, and does the whole
+        // thing in one batch. Updating item by item let a later item collide with
+        // one already put back and push it off its saved spot for good — the
+        // restored layout was then not the one the user left. load() also re-applies
+        // gridstack's w/h defaults, which save() omits when they are 1.
+        // `false` keeps add/remove off: Flow owns which children exist.
+        this.grid.load(known, false);
     }
 
     private intAttr(el: HTMLElement, name: string): number | undefined {

src/main/java/com/example/components/GridStackLayout.java

@@ -179,18 +179,17 @@ public class GridStackLayout extends Component implements HasSize, HasStyle {
             String id = node.path("id").asString(null);
             if (id == null) continue;
 
-            findItem(id).ifPresent(item -> item.setPosition(
-                    node.path("x").asInt(),
-                    node.path("y").asInt(),
-                    node.path("w").asInt(),
-                    node.path("h").asInt()));
+            // gridstack omits w/h from its saved layout when they are 1, so a
+            // missing value means 1 — defaulting to 0 wrote a zero-sized widget
+            // back onto the item and lost its size on the next attach.
+            int x = node.path("x").asInt(0);
+            int y = node.path("y").asInt(0);
+            int w = node.path("w").asInt(1);
+            int h = node.path("h").asInt(1);
 
-            positions.add(new GridStackItem.Position(
-                    id,
-                    node.path("x").asInt(),
-                    node.path("y").asInt(),
-                    node.path("w").asInt(),
-                    node.path("h").asInt()));
+            findItem(id).ifPresent(item -> item.setPosition(x, y, w, h));
+
+            positions.add(new GridStackItem.Position(id, x, y, w, h));
         }
 
         fireEvent(new LayoutChangeEvent(this, true, positions));