feat: added functionality of saving and loadiing

for supported browsers, using the File System Access API.
otherwise, fallback to download the file and then you can load from download

ref: N25B-189

src/pages/VisProgPage/VisProg.tsx

@@ -20,6 +20,7 @@ import graphReducer from "./visualProgrammingUI/GraphReducer.ts";
 import useFlowStore from './visualProgrammingUI/VisProgStores.tsx';
 import type {FlowState} from './visualProgrammingUI/VisProgTypes.tsx';
 import styles from './VisProg.module.css'
+import SaveLoadPanel from './visualProgrammingUI/components/SaveLoadPanel.tsx';
 
 // --| config starting params for flow |--
 
@@ -100,6 +101,9 @@ const VisProgUI = () => {
           <Panel position="top-center" className={styles.dndPanel}>
             <DndToolbar/> {/* contains the drag and drop panel for nodes */}
           </Panel>
+          <Panel position = "bottom-left" className={styles.saveLoadPanel}>
+            <SaveLoadPanel></SaveLoadPanel>
+            </Panel>
           <Controls/>
           <Background/>
         </ReactFlow>

src/pages/VisProgPage/visualProgrammingUI/components/DragDropSidebar.tsx

@@ -150,22 +150,7 @@ export function DndToolbar() {
   );
 
   return (
-    
-    
     <div>
-      <div className={`flex-col gap-lg padding-md ${styles.saveLoadPanel }`}>
-        <div className="description">
-          You can save and load your graph here.
-        </div>
-        <div className={`flex-row gap-lg ${styles.dndNodeContainer}`}>
-          <button className={styles.draggableNodePhase}>
-            Save Graph
-          </button>
-          <button className={styles.draggableNodeNorm} >
-            Load Graph
-          </button>
-        </div>
-      </div>
 
       <div className={`flex-col gap-lg padding-md ${styles.innerDndPanel}`}>
         <div className="description">

src/pages/VisProgPage/visualProgrammingUI/components/SaveLoadPanel.tsx

@@ -0,0 +1,136 @@
+import React from "react";
+import useFlowStore from "../VisProgStores";
+import styles from "../../VisProg.module.css";
+import { useReactFlow, type Edge } from "@xyflow/react";
+import type { AppNode } from "../VisProgTypes";
+
+type SavedProject = {
+  version: 1;
+  name: string;
+  savedAt: string; // ISO timestamp
+  nodes: AppNode[];
+  edges: Edge[];
+};
+
+
+
+function makeProjectBlob(name: string, nodes: AppNode[], edges: Edge[]): Blob {
+  const payload = {
+    version: 1,
+    name,
+    savedAt: new Date().toISOString(),
+    nodes,
+    edges,
+  };
+  return new Blob([JSON.stringify(payload, null, 2)], { type: "application/json" });
+}
+
+async function saveWithPicker(defaultName: string, blob: Blob) {
+  // @ts-expect-error: not in lib.dom.d.ts everywhere
+  if (window.showSaveFilePicker) {
+    // @ts-expect-error
+    const handle = await window.showSaveFilePicker({
+      suggestedName: `${defaultName}.visprog.json`,
+      types: [{ description: "Visual Program Project", accept: { "application/json": [".visprog.json", ".json"] } }],
+    });
+    const writable = await handle.createWritable();
+    await writable.write(blob);
+    await writable.close();
+    return;
+  }
+  // Fallback if File system API is not supported
+  const url = URL.createObjectURL(blob);
+  const a = document.createElement("a");
+  a.href = url;
+  a.download = `${defaultName}.visprog.json`;
+  a.click();
+  URL.revokeObjectURL(url);
+}
+
+async function loadWithPicker(): Promise<SavedProject | null> {
+  try {
+    // @ts-expect-error
+    if (window.showOpenFilePicker) {
+      // @ts-expect-error
+      const [handle] = await window.showOpenFilePicker({
+        multiple: false,
+        types: [{ description: "Visual Program Project", accept: { "application/json": [".visprog.json", ".json", ".txt"] } }],
+      });
+      const file = await handle.getFile();
+      return JSON.parse(await file.text()) as SavedProject;
+    }
+    // Fallback: input
+    return await new Promise<SavedProject | null>((resolve) => {
+      const input = document.createElement("input");
+      input.type = "file";
+      input.accept = ".visprog.json,.json,.txt,application/json,text/plain";
+      input.onchange = async () => {
+        const file = input.files?.[0];
+        if (!file) return resolve(null);
+        try {
+          resolve(JSON.parse(await file.text()) as SavedProject);
+        } catch {
+          resolve(null);
+        }
+      };
+      input.click();
+    });
+  } catch {
+    return null;
+  }
+}
+
+export default function SaveLoadPanel() {
+  const nodes = useFlowStore((s) => s.nodes) as AppNode[];
+  const edges = useFlowStore((s) => s.edges) as Edge[];
+  const setNodes = useFlowStore((s) => s.setNodes);
+  const setEdges = useFlowStore((s) => s.setEdges);
+
+  const onSave = async () => {
+    try {
+      const nameGuess =
+        (nodes.find((n) => n.type === "start")?.data?.label as string) || "visual-program";
+      const blob = makeProjectBlob(nameGuess, nodes, edges);
+      await saveWithPicker(nameGuess, blob);
+    } catch (e) {
+      console.error(e);
+      alert("Saving failed. See console.");
+    }
+  };
+
+  const onLoad = async () => {
+    try {
+      const proj = await loadWithPicker();
+      if (!proj) return;
+
+      if (proj.version !== 1 || !Array.isArray(proj.nodes) || !Array.isArray(proj.edges)) {
+        alert("Invalid project file format.");
+        return;
+      }
+
+      //We clear all the current edges and nodes
+      setEdges([]);
+      setNodes([]);
+
+      //set all loaded nodes and edges into the VisProg
+      const loadedNodes = proj.nodes as AppNode[];
+      const loadedEdges = proj.edges as Edge[];
+      setNodes(loadedNodes);
+      setEdges(loadedEdges);
+
+    } catch (e) {
+      console.error(e);
+      alert("Loading failed. See console.");
+    }
+  };
+
+  return (
+    <div className={`flex-col gap-lg padding-md ${styles.saveLoadPanel}`}>
+      <div className="description">You can save and load your graph here.</div>
+      <div className={`flex-row gap-lg ${styles.dndNodeContainer}`}>
+        <button onClick={onSave} className={styles.draggableNodePhase}>Save Graph</button>
+        <button onClick={onLoad} className={styles.draggableNodeNorm}>Load Graph</button>
+      </div>
+    </div>
+  );
+}