fix(slideshow): finish remaining split-PR review findings (#1594)

* fix(slideshow): address split-PR review findings on #1585

Genuinely-open findings from the #1580/#1590/#1591/#1592 reviews (the rest were
already fixed on this branch: CSP handlers, manifest version, UUID ids, float
keys, presenter 1s-timer):

core (#1580):
- isManifest rejects a non-object/array manifest (e.g. [42,null]) explicitly
- resolveSlideshow flags duplicate slideSequence ids instead of silent overwrite

player (#1590):
- present() window.open uses noopener,noreferrer (audience syncs via channel)
- BroadcastChannel name is per-deck (keyed on pathname) to avoid same-origin
  cross-talk between decks
- add observedAttributes + attributeChangedCallback so runtime sound/mode toggles
  re-render

studio (#1591/#1592):
- persistSlideshowManifest no-op gate (skip write when HTML is unchanged)
- surface persist failures (console.error) instead of silent .catch(()=>{})
- confirm before deleting a branch sequence (data-loss + dangling hotspots)

+ tests for the collision + non-object-manifest rejection. 20 core / 106 player /
53 studio pass; tsc/lint/fmt/fallow clean; deck still renders.

* fix(slideshow): finish remaining split-PR review findings

The larger items from the #1580/#1590/#1591/#1592 reviews (the rest landed in
#1585):

core (#1580):
- dedup isSceneLikeCompositionId — shared slideshow/sceneId.ts, used by both the
  lint rule and the runtime scene-window computation (no more mirror-and-drift)

player (#1590 / #1592):
- onKey: when multiple decks share a page, drop the unfocused-convenience so a
  key drives only the focused deck
- slow-iframe recovery: if the scene timeline posts after the wait times out
  (empty scenes), re-init once so sceneId slides resolve instead of being dropped

studio (#1591):
- persistSlideshowManifest validates the built island round-trips before writing
- reorderBranchSlide helper + BranchTree up/down controls (parallel to main-line
  reorder), with a branch-position indicator

+ tests for reorderBranchSlide. core 228 / player 106 / studio (panel) 46 pass;
tsc/lint/fmt/fallow clean.

* fix(player,cli): use fileURLToPath for path resolution (Windows CI)

new URL(...).pathname yields a leading-slash drive path ("/D:/...") on Windows,
which broke:
- packages/player/vitest.config.ts — the @hyperframes/core/slideshow alias
  resolved to a nonexistent path, failing the player slideshow tests on the
  Windows render-verification CI (passed on macOS/Linux where pathname is clean)
- packages/cli/src/utils/compositionServer.ts helperDir — same bug in the
  play/present bundle-path resolution

fileURLToPath converts file:// URLs to correct OS paths on all platforms.
Player slideshow tests pass; present serves + resolves bundles.

* fix(producer): fileURLToPath for the renders dir (Windows)

DEFAULT_RENDERS_DIR used new URL(import.meta.url).pathname, which is "/D:/..."
on Windows and resolves to a bogus path — affects the Windows render pipeline.
Last of the .pathname -> fileURLToPath fixes (repo-wide src sweep now clean).

packages/player/src/slideshow/hyperframes-slideshow.test.ts

@@ -2,6 +2,7 @@
 import { describe, it, expect, beforeEach, afterEach, vi } from "vitest";
 import { handleRuntimeMessage } from "../runtime-message-handler.js";
 import { dropInvalidSlides } from "./hyperframes-slideshow.js";
+import { slideshowChannelName } from "./slideshowPresenter.js";
 
 // Dynamic import defers custom-element registration until happy-dom is active.
 // (Static top-level imports execute before the test environment is set up, which
@@ -524,7 +525,7 @@ describe("<hyperframes-slideshow> presenter mode", () => {
   const tick = () => new Promise<void>((r) => setTimeout(r, 0));
 
   it("audience mode: mirrors full position (sequence + slide + fragment) via syncTo", async () => {
-    const presenterChannel = new BroadcastChannel("hf-slideshow");
+    const presenterChannel = new BroadcastChannel(slideshowChannelName());
     const { el, getLastSync } = makeAudienceEl();
 
     await tick();
@@ -542,7 +543,7 @@ describe("<hyperframes-slideshow> presenter mode", () => {
   });
 
   it("audience mode: mirrors a branch position too (full sequenceId forwarded to syncTo)", async () => {
-    const presenterChannel = new BroadcastChannel("hf-slideshow");
+    const presenterChannel = new BroadcastChannel(slideshowChannelName());
     const { el, getLastSync } = makeAudienceEl();
 
     await tick();
@@ -566,7 +567,7 @@ describe("<hyperframes-slideshow> presenter mode", () => {
 
   it("presenter mode: posts position to channel on controller onChange", async () => {
     const received: unknown[] = [];
-    const listenerChannel = new BroadcastChannel("hf-slideshow");
+    const listenerChannel = new BroadcastChannel(slideshowChannelName());
     listenerChannel.onmessage = (e: MessageEvent) => received.push(e.data);
 
     const { el, triggerChange } = makePresenterEl();
@@ -608,7 +609,7 @@ describe("<hyperframes-slideshow> presenter mode", () => {
     await tick();
 
     const received: unknown[] = [];
-    const spy = new BroadcastChannel("hf-slideshow");
+    const spy = new BroadcastChannel(slideshowChannelName());
     spy.onmessage = (e: MessageEvent) => received.push(e.data);
 
     el.remove(); // triggers disconnectedCallback

packages/player/src/slideshow/hyperframes-slideshow.ts

@@ -114,6 +114,17 @@ export class HyperframesSlideshow extends HTMLElement {
     }
   }
 
+  // Observe the attributes the component reads so runtime toggles take effect.
+  static get observedAttributes(): string[] {
+    return ["sound", "mode"];
+  }
+
+  attributeChangedCallback(): void {
+    // Re-render once bound so a flipped `sound`/`mode` is reflected (mute button,
+    // audience-vs-presenter chrome). No-op before the controller binds.
+    if (this.controller) this.render();
+  }
+
   connectedCallback(): void {
     this.disconnected = false;
     this.initInFlight = false;
@@ -178,7 +189,9 @@ export class HyperframesSlideshow extends HTMLElement {
    */
   present(): void {
     const sep = location.search ? "&" : "?";
-    window.open(location.href + sep + "mode=audience", "_blank");
+    // noopener,noreferrer: the audience window must not get a reference back to
+    // this window (it syncs over BroadcastChannel, not window.opener).
+    window.open(location.href + sep + "mode=audience", "_blank", "noopener,noreferrer");
     this.setAttribute("data-hf-presenting", "true");
     this.presenterStartMs = Date.now();
     if (this.presenterInterval === null) {
@@ -278,6 +291,19 @@ export class HyperframesSlideshow extends HTMLElement {
       };
 
       this.bindController(new SlideshowController(port, cleaned));
+
+      // Slow-iframe recovery: if the scene timeline hadn't posted yet (empty
+      // scenes → sceneId-based slides were dropped), re-init once when it finally
+      // arrives so those slides resolve instead of being permanently lost.
+      if (scenes.length === 0 && manifest.slides.length > 0) {
+        playerEl.addEventListener(
+          "scenes",
+          () => {
+            if (gen === this.initGeneration) void this.init();
+          },
+          { once: true },
+        );
+      }
     } finally {
       this.initInFlight = false;
     }
@@ -318,7 +344,10 @@ export class HyperframesSlideshow extends HTMLElement {
     // Arrows act even when nothing is focused (active === body/null) so a freshly
     // loaded deck responds without a click; Space/Backspace have strong page-level
     // defaults (scroll / history) so they only act when the deck actually has focus.
-    const ambient = focused || active === document.body || active === null;
+    // When several decks share a page, drop the unfocused-convenience so a key
+    // doesn't drive every instance at once — only the focused deck responds.
+    const multiInstance = document.querySelectorAll("hyperframes-slideshow").length > 1;
+    const ambient = focused || (!multiInstance && (active === document.body || active === null));
     if (e.key === "ArrowRight") {
       if (!ambient) return;
       this.controller.next();

packages/player/src/slideshow/slideshowPresenter.ts

@@ -27,6 +27,16 @@ function isGotoMessage(data: unknown): data is GotoMessage {
  * Presenter (default) mode: posts position updates to the channel.
  * Audience mode: listens for goto messages and calls the provided handler.
  */
+/**
+ * Per-deck channel name. The presenter and its audience window load the same URL
+ * (path), so keying on pathname keeps them paired while isolating other decks
+ * presenting on the same origin (which would otherwise cross-talk on a fixed name).
+ */
+export function slideshowChannelName(): string {
+  const path = typeof location !== "undefined" ? location.pathname : "";
+  return `hf-slideshow:${path}`;
+}
+
 export class SlideshowChannel {
   private channel: BroadcastChannel | null = null;
 
@@ -35,7 +45,7 @@ export class SlideshowChannel {
     private readonly onGoto: (msg: GotoMessage) => void,
   ) {
     try {
-      this.channel = new BroadcastChannel("hf-slideshow");
+      this.channel = new BroadcastChannel(slideshowChannelName());
     } catch {
       // BroadcastChannel unavailable (e.g. unsupported env); degrade silently.
       return;

packages/player/vitest.config.ts

@@ -1,7 +1,10 @@
 import { defineConfig } from "vitest/config";
-import { resolve } from "path";
+import { resolve } from "node:path";
+import { fileURLToPath } from "node:url";
 
-const coreRoot = resolve(new URL("..", import.meta.url).pathname, "core/src");
+// fileURLToPath (not URL.pathname): on Windows .pathname yields "/D:/..." with a
+// leading slash, which breaks resolve() and the alias below.
+const coreRoot = resolve(fileURLToPath(new URL("../core/src", import.meta.url)));
 
 export default defineConfig({
   resolve: {