diff --git a/src/components/three/XRBroadcastMirror.tsx b/src/components/three/XRBroadcastMirror.tsx
new file mode 100644
index 0000000..142cca3
--- /dev/null
+++ b/src/components/three/XRBroadcastMirror.tsx
@@ -0,0 +1,119 @@
+import { useEffect, useRef } from 'react';
+import { useFrame, useThree } from '@react-three/fiber';
+import * as THREE from 'three';
+import { setBroadcastSource } from '@/lib/webrtc/broadcastSource';
+
+interface XRBroadcastMirrorProps {
+  enabled: boolean;
+  width?: number;
+  height?: number;
+  /** Solid background color used in place of real passthrough (privacy + clarity). */
+  backgroundColor?: string;
+}
+
+/**
+ * Renders the current scene to an OFFSCREEN opaque canvas every frame so a
+ * MediaStream can capture it. The main XR canvas uses alpha:true for
+ * passthrough — viewers receiving captureStream() of that would see only
+ * the 3D content over transparency. This mirror gives them a usable picture.
+ */
+export function XRBroadcastMirror({
+  enabled,
+  width = 1280,
+  height = 720,
+  backgroundColor = '#1a1a1a',
+}: XRBroadcastMirrorProps) {
+  const { gl, scene } = useThree();
+  const canvasRef = useRef<HTMLCanvasElement | null>(null);
+  const rendererRef = useRef<THREE.WebGLRenderer | null>(null);
+  const mirrorCamRef = useRef<THREE.PerspectiveCamera | null>(null);
+
+  // Create / dispose the offscreen renderer
+  useEffect(() => {
+    if (!enabled) return;
+    const canvas = document.createElement('canvas');
+    canvas.width = width;
+    canvas.height = height;
+    canvasRef.current = canvas;
+
+    const renderer = new THREE.WebGLRenderer({
+      canvas,
+      alpha: false,
+      antialias: true,
+      powerPreference: 'high-performance',
+      preserveDrawingBuffer: false,
+    });
+    renderer.setPixelRatio(1);
+    renderer.setSize(width, height, false);
+    renderer.setClearColor(new THREE.Color(backgroundColor), 1);
+    renderer.outputColorSpace = THREE.SRGBColorSpace;
+    rendererRef.current = renderer;
+
+    mirrorCamRef.current = new THREE.PerspectiveCamera(70, width / height, 0.01, 100);
+
+    setBroadcastSource(canvas);
+
+    return () => {
+      setBroadcastSource(null);
+      renderer.dispose();
+      rendererRef.current = null;
+      canvasRef.current = null;
+      mirrorCamRef.current = null;
+    };
+  }, [enabled, width, height, backgroundColor]);
+
+  // Per-frame mirror render (throttled to ~24 fps to save GPU)
+  const lastTime = useRef(0);
+  useFrame(() => {
+    if (!enabled) return;
+    const renderer = rendererRef.current;
+    const mirrorCam = mirrorCamRef.current;
+    if (!renderer || !mirrorCam) return;
+
+    const now = performance.now();
+    if (now - lastTime.current < 42) return; // ~24 fps cap
+    lastTime.current = now;
+
+    // Pick the best available camera: XR camera if in session, else main camera
+    let srcCam: THREE.Camera | null = null;
+    const xrCam = (gl.xr as unknown as { isPresenting?: boolean; getCamera?: () => THREE.ArrayCamera }).getCamera?.();
+    const isPresenting = (gl.xr as unknown as { isPresenting?: boolean }).isPresenting;
+    if (isPresenting && xrCam && (xrCam as THREE.ArrayCamera).cameras?.length) {
+      srcCam = (xrCam as THREE.ArrayCamera).cameras[0]; // left eye
+    }
+
+    if (srcCam instanceof THREE.PerspectiveCamera) {
+      mirrorCam.fov = srcCam.fov;
+      mirrorCam.near = srcCam.near;
+      mirrorCam.far = srcCam.far;
+    }
+    if (srcCam) {
+      srcCam.updateMatrixWorld(true);
+      mirrorCam.position.setFromMatrixPosition(srcCam.matrixWorld);
+      mirrorCam.quaternion.setFromRotationMatrix(srcCam.matrixWorld);
+    } else {
+      // Fallback: use the main R3F camera (desktop preview)
+      const main = (gl as unknown as { __mainCam?: THREE.Camera }).__mainCam;
+      if (main) {
+        main.updateMatrixWorld(true);
+        mirrorCam.position.setFromMatrixPosition(main.matrixWorld);
+        mirrorCam.quaternion.setFromRotationMatrix(main.matrixWorld);
+        if (main instanceof THREE.PerspectiveCamera) {
+          mirrorCam.fov = main.fov;
+          mirrorCam.near = main.near;
+          mirrorCam.far = main.far;
+        }
+      }
+    }
+    mirrorCam.aspect = width / height;
+    mirrorCam.updateProjectionMatrix();
+
+    try {
+      renderer.render(scene, mirrorCam);
+    } catch (e) {
+      console.warn('[XRBroadcastMirror] render failed', e);
+    }
+  });
+
+  return null;
+}
diff --git a/src/components/three/XRPanel3D.tsx b/src/components/three/XRPanel3D.tsx
new file mode 100644
index 0000000..248fe8f
--- /dev/null
+++ b/src/components/three/XRPanel3D.tsx
@@ -0,0 +1,103 @@
+import { useState, ReactNode } from 'react';
+import { Text } from '@react-three/drei';
+import * as THREE from 'three';
+
+interface XR3DButtonProps {
+  position?: [number, number, number];
+  size?: [number, number];
+  label: string;
+  icon?: string;
+  active?: boolean;
+  disabled?: boolean;
+  onClick?: () => void;
+  color?: string;
+  fontSize?: number;
+}
+
+/** Flat 3D button suitable for in-XR HUD. Reacts to controller raycast. */
+export function XR3DButton({
+  position = [0, 0, 0],
+  size = [0.08, 0.025],
+  label,
+  icon,
+  active = false,
+  disabled = false,
+  onClick,
+  color,
+  fontSize = 0.008,
+}: XR3DButtonProps) {
+  const [hovered, setHovered] = useState(false);
+  const [w, h] = size;
+
+  const bgColor = disabled
+    ? '#222'
+    : active
+      ? (color ?? '#3b82f6')
+      : hovered
+        ? '#444'
+        : '#1a1a1a';
+  const fgColor = disabled ? '#555' : active ? '#ffffff' : '#e5e7eb';
+  const borderColor = active ? (color ?? '#3b82f6') : hovered ? '#666' : '#333';
+
+  return (
+    <group
+      position={position}
+      onPointerOver={(e) => { e.stopPropagation(); if (!disabled) setHovered(true); }}
+      onPointerOut={(e) => { e.stopPropagation(); setHovered(false); }}
+      onClick={(e) => { e.stopPropagation(); if (!disabled && onClick) onClick(); }}
+    >
+      {/* Border */}
+      <mesh position={[0, 0, -0.0005]}>
+        <planeGeometry args={[w + 0.002, h + 0.002]} />
+        <meshBasicMaterial color={borderColor} transparent opacity={0.95} />
+      </mesh>
+      {/* Background */}
+      <mesh>
+        <planeGeometry args={[w, h]} />
+        <meshBasicMaterial color={bgColor} transparent opacity={0.92} side={THREE.DoubleSide} />
+      </mesh>
+      <Text
+        position={[0, 0, 0.001]}
+        fontSize={fontSize}
+        color={fgColor}
+        anchorX="center"
+        anchorY="middle"
+        maxWidth={w * 0.95}
+      >
+        {icon ? `${icon}  ${label}` : label}
+      </Text>
+    </group>
+  );
+}
+
+interface XR3DPanelProps {
+  position?: [number, number, number];
+  size?: [number, number];
+  color?: string;
+  opacity?: number;
+  children?: ReactNode;
+}
+
+/** Background panel for grouping XR3DButtons. */
+export function XR3DPanel({
+  position = [0, 0, 0],
+  size = [0.4, 0.3],
+  color = '#0a0a0a',
+  opacity = 0.85,
+  children,
+}: XR3DPanelProps) {
+  const [w, h] = size;
+  return (
+    <group position={position}>
+      <mesh position={[0, 0, -0.001]}>
+        <planeGeometry args={[w + 0.004, h + 0.004]} />
+        <meshBasicMaterial color="#3b82f6" transparent opacity={0.6} />
+      </mesh>
+      <mesh>
+        <planeGeometry args={[w, h]} />
+        <meshBasicMaterial color={color} transparent opacity={opacity} side={THREE.DoubleSide} />
+      </mesh>
+      {children}
+    </group>
+  );
+}
diff --git a/src/lib/webrtc/broadcastSource.ts b/src/lib/webrtc/broadcastSource.ts
new file mode 100644
index 0000000..163b2cd
--- /dev/null
+++ b/src/lib/webrtc/broadcastSource.ts
@@ -0,0 +1,20 @@
+/**
+ * Lightweight registry that lets the XR mirror expose its offscreen canvas
+ * as the preferred broadcast source. ShareButton checks here first.
+ */
+let activeCanvas: HTMLCanvasElement | null = null;
+const listeners = new Set<(c: HTMLCanvasElement | null) => void>();
+
+export function setBroadcastSource(c: HTMLCanvasElement | null) {
+  activeCanvas = c;
+  listeners.forEach((cb) => cb(c));
+}
+
+export function getBroadcastSource(): HTMLCanvasElement | null {
+  return activeCanvas;
+}
+
+export function onBroadcastSourceChange(cb: (c: HTMLCanvasElement | null) => void) {
+  listeners.add(cb);
+  return () => listeners.delete(cb);
+}