[LLV] Fix phx-hook mounting inside LocalLiveView

local-live-view/assets/local_live_view/types.ts

@@ -68,6 +68,7 @@ export interface LLVView {
     opts: object,
   ): void;
   addHook: (el: Element) => unknown;
+  ownsElement?: (el: Element) => boolean;
   destroy?: (callback?: () => void) => void;
 }
 

local-live-view/assets/local_live_view/view_setup.ts

@@ -20,6 +20,13 @@ export function setupFakeView(
   // stock Channel/Push machinery over the PopcornTransport.
   view.channel = popcornSocket.channel(`lv:${llvId}`);
 
+  // LLV roots have no data-phx-session, so stock ownsElement (closestViewEl) would
+  // assign children to the host LiveView or reject them entirely — and addHook
+  // would skip every phx-hook under this container. Own the subtree by containment.
+  view.ownsElement = function (this: LLVView, el: Element) {
+    return this.el === el || this.el.contains(el);
+  };
+
   // addHook: skip the root element to prevent Phoenix from trying to register it
   // as a hook within this view's scope — hooks on children are still processed normally.
   const origAddHook = view.addHook.bind(view);

local-live-view/priv/static/local_live_view.js

@@ -524,6 +524,12 @@ function setupFakeView(socket, views, popcornSocket, pop_view_el) {
     // diffs, out-of-band "diff" frames, ref bookkeeping — runs through the
     // stock Channel/Push machinery over the PopcornTransport.
     view.channel = popcornSocket.channel(`lv:${llvId}`);
+    // LLV roots have no data-phx-session, so stock ownsElement (closestViewEl) would
+    // assign children to the host LiveView or reject them entirely — and addHook
+    // would skip every phx-hook under this container. Own the subtree by containment.
+    view.ownsElement = function (el) {
+        return this.el === el || this.el.contains(el);
+    };
     // addHook: skip the root element to prevent Phoenix from trying to register it
     // as a hook within this view's scope — hooks on children are still processed normally.
     const origAddHook = view.addHook.bind(view);