frontend-app-api: add session boundary app initialization

Instantiate the app shell up to app/root.children during sign-in, then rebuild the full tree after sign-in without cloning the app tree.

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
Made-with: Cursor

packages/frontend-app-api/src/tree/instantiateAppNodeTree.ts

@@ -509,6 +509,9 @@ export function instantiateAppNodeTree(
   apis: ApiHolder,
   collector: ErrorCollector,
   extensionFactoryMiddleware?: ExtensionFactoryMiddleware,
+  options?: {
+    stopAtAttachment?(ctx: { node: AppNode; input: string }): boolean;
+  },
 ): boolean {
   function createInstance(node: AppNode): AppNodeInstance | undefined {
     if (node.instance) {
@@ -521,6 +524,9 @@ export function instantiateAppNodeTree(
     const instantiatedAttachments = new Map<string, AppNode[]>();
 
     for (const [input, children] of node.edges.attachments) {
+      if (options?.stopAtAttachment?.({ node, input })) {
+        continue;
+      }
       const instantiatedChildren = children.flatMap(child => {
         const childInstance = createInstance(child);
         if (!childInstance) {