fix(stream): tie broadcast-helper to the stream lifecycle, enforce STREAM_BROWSER, fix fullscreen window

Addresses review of the STREAM_BROWSER / broadcast-defaults work:

- SelfbotStreamer now spawns broadcast-helper.mjs on stream start and kills it on
  stop/self-end (alongside capture + keepalive). The ad-skip, subtitle rule and
  fullscreen-toolbar-hide are therefore guaranteed broadcast-wide defaults tied
  to the broadcast - not a manual process. Fail-open: if node/Chrome deps are
  absent the stream runs without the helper. Verified the helper is a child of
  the broadcast holder and armed.
- Enforce STREAM_BROWSER at the streamer (start() returns early when
  screenBrowser===false), so EVERY caller including stream-hold.ts is voice-only
  when it's off, not just the slash command. stream-hold.ts reads STREAM_BROWSER.
- Fix broadcast-helper fullscreen: resolve the window of the tab actually in
  HTML5 fullscreen (via its CDP targetId) instead of the first HTTP tab, so the
  right Chrome window is toggled when multiple windows exist.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

bot/src/stream/selfbot.ts

@@ -26,6 +26,7 @@ export class SelfbotStreamer implements ScreenStreamer {
   private streamer: any = null;
   private capture: ChildProcess | null = null;
   private keepalive: VncKeepalive | null = null;
+  private helper: ChildProcess | null = null;
   private controller: AbortController | null = null;
   private active = false;
 
@@ -79,6 +80,12 @@ export class SelfbotStreamer implements ScreenStreamer {
 
   async start(ctx: StreamContext): Promise<string> {
     if (this.active) return "이미 송출 중입니다.";
+    // Screen-share gate: STREAM_BROWSER=false means voice + API/MCP only, so we
+    // never go Live. Enforced HERE (not just in the slash command) so every
+    // caller - including stream-hold.ts - respects it.
+    if (this.config.screenBrowser === false) {
+      return "화면 공유(브라우저) 모드가 꺼져 있습니다 (STREAM_BROWSER=false). 음성 + API/MCP 모드로만 동작합니다.";
+    }
     if (!this.config.selfbotToken) {
       return "DISCORD_SELFBOT_TOKEN이 설정되지 않았습니다 (.env). 버너 계정 토큰을 넣어주세요.";
     }
@@ -97,6 +104,7 @@ export class SelfbotStreamer implements ScreenStreamer {
     let streamer: any = null;
     let capture: ChildProcess | null = null;
     let keepalive: VncKeepalive | null = null;
+    let helper: ChildProcess | null = null;
 
     try {
       const { selfbot, vs } = await this.loadLib();
@@ -191,6 +199,23 @@ export class SelfbotStreamer implements ScreenStreamer {
         keepalive.start();
       }
 
+      // Browser-side broadcast defaults (ad-skip, subtitle rule, fullscreen
+      // toolbar hiding) run in a small CDP helper tied to the stream lifecycle.
+      // It attaches to the on-screen Chrome (CDP_PORT) and fail-opens if Chrome
+      // or its deps are absent, so it can never break the stream.
+      try {
+        const helperPath = new URL("../../scripts/stream-test/broadcast-helper.mjs", import.meta.url).pathname;
+        helper = this.helper = spawn("node", [helperPath], {
+          env: { ...process.env, CDP_PORT: process.env.CDP_PORT ?? "9222" },
+          stdio: "ignore",
+        });
+        helper.on("error", () => {
+          /* node/playwright missing: the stream runs without the helper */
+        });
+      } catch {
+        /* ignore */
+      }
+
       const { command, output } = prepareStream(
         capture.stdout,
         {
@@ -234,6 +259,11 @@ export class SelfbotStreamer implements ScreenStreamer {
           } catch {
             /* ignore */
           }
+          try {
+            helper?.kill();
+          } catch {
+            /* ignore */
+          }
           try {
             streamer?.leaveVoice?.();
             streamer?.client?.destroy?.();
@@ -242,6 +272,7 @@ export class SelfbotStreamer implements ScreenStreamer {
           }
           if (this.capture === capture) this.capture = null;
           if (this.keepalive === keepalive) this.keepalive = null;
+          if (this.helper === helper) this.helper = null;
           if (this.streamer === streamer) this.streamer = null;
           this.controller = null;
           this.active = false;
@@ -262,6 +293,11 @@ export class SelfbotStreamer implements ScreenStreamer {
       } catch {
         /* ignore */
       }
+      try {
+        helper?.kill();
+      } catch {
+        /* ignore */
+      }
       try {
         streamer?.leaveVoice?.();
         streamer?.client?.destroy?.();
@@ -275,6 +311,7 @@ export class SelfbotStreamer implements ScreenStreamer {
       if (this.controller === controller) {
         if (this.capture === capture) this.capture = null;
         if (this.keepalive === keepalive) this.keepalive = null;
+        if (this.helper === helper) this.helper = null;
         if (this.streamer === streamer) this.streamer = null;
         this.controller = null;
         this.active = false;
@@ -299,6 +336,12 @@ export class SelfbotStreamer implements ScreenStreamer {
       /* ignore */
     }
     this.keepalive = null;
+    try {
+      this.helper?.kill();
+    } catch {
+      /* ignore */
+    }
+    this.helper = null;
     try {
       this.streamer?.leaveVoice?.();
       this.streamer?.client?.destroy?.();