Fix : XR thread resubmits the last valid frame during stall + Eager Frame Heartbeat option

aurora-main/lib/stereo_mirror.hpp

@@ -0,0 +1,42 @@
+#pragma once
+
+#include <aurora/gfx.h>
+
+namespace aurora::stereo {
+
+enum class MirrorPlan { Mono, LeftEye, RightEye, BothEyes, Black };
+
+// Owned by the frame worker, alongside the persistent eye textures. An absent
+// XR packet means the headset is retaining its image, not switching to mono.
+class MirrorState {
+public:
+  MirrorPlan Resolve(AuroraStereoMirrorView view, bool providerActive,
+                     bool freshOutput, bool immersiveReplay) noexcept {
+    if (!providerActive) {
+      Reset();
+      return MirrorPlan::Mono;
+    }
+    if (freshOutput) {
+      m_immersive = immersiveReplay;
+    }
+    switch (view) {
+    case AURORA_STEREO_MIRROR_NONE:
+      return MirrorPlan::Black;
+    case AURORA_STEREO_MIRROR_BOTH_EYES:
+      return m_immersive ? MirrorPlan::BothEyes : MirrorPlan::Mono;
+    case AURORA_STEREO_MIRROR_LEFT_EYE:
+      return m_immersive ? MirrorPlan::LeftEye : MirrorPlan::Mono;
+    case AURORA_STEREO_MIRROR_RIGHT_EYE:
+      return m_immersive ? MirrorPlan::RightEye : MirrorPlan::Mono;
+    default:
+      return MirrorPlan::Mono;
+    }
+  }
+
+  void Reset() noexcept { m_immersive = false; }
+
+private:
+  bool m_immersive = false;
+};
+
+} // namespace aurora::stereo