diff --git a/_Design/glossary.md b/_Design/glossary.md
index 01efd25..370cea5 100644
--- a/_Design/glossary.md
+++ b/_Design/glossary.md
@@ -12,16 +12,15 @@ pool in a thin class instead:
 
 ```
 ResourceRegistry
- ├── meshes        Pool<Mesh, MeshHandle>
- ├── renderTargets RenderTargetPool → RenderTargetHandle
- │                 (wraps Pool; waits for the GPU on release, applies resizes)
- ├── scenes        Pool<Scene, SceneHandle>
- ├── textures      (planned)
- └── materials     (planned)
+ ├── meshPool          Pool<Mesh, MeshHandle>
+ ├── renderTargetPool  RenderTargetPool → RenderTargetHandle
+ │                     (wraps Pool; waits for the GPU on release, applies resizes)
+ ├── texturePool       (planned)
+ └── materialPool      (planned)
 ```
 
 Engine code (`Application`, `ImGuiRenderer`, `SceneRenderer`) uses the pools
-directly, e.g. `resources.renderTargets.get(handle)`.
+directly, e.g. `resources.renderTargetPool.get(handle)`.
 
 A Handle is a small (index, generation) pair. The index locates the slot in
 the pool; the generation is bumped when that slot is released, so a Handle
@@ -277,12 +276,14 @@ This is primarily a UI concept, rather than a GPU concept.
 A PanelRegistry owns Panels on the caller's behalf and hands out lightweight
 PanelHandles instead of pointers or ownership.
 
-Internally it's a generation-checked slot pool, the same shape ResourceRegistry's
-`Pool<T, Handle>` uses:
+Internally it wraps a `Pool<Panel, PanelHandle>` (the same generation-checked
+slot pool ResourceRegistry uses, in `sophia/util/pool.hpp`) and adds the
+Panel-specific parts: lookup by type or name, and the default dock layout:
 
 ```
 PanelRegistry
- └── Slot { Panel, generation }  →  PanelHandle
+ └── Pool<Panel, PanelHandle>
+      └── Slot { Panel, generation }  →  PanelHandle
 ```
 
 Typical lifecycle:
@@ -300,6 +301,34 @@ Each frame, update(frameInfo) calls onUpdate on every visible Panel it holds.
 Think: "Where do I register or look up a UI panel by handle, without owning
 its lifetime directly?"
 
+## SceneRegistry
+
+A SceneRegistry owns Scenes on the caller's behalf and hands out lightweight
+SceneHandles instead of pointers or ownership. Like PanelRegistry, it is owned
+by Application and reached from frontend code directly (`scenes()`), rather than
+through ResourceRegistryRef: scenes are CPU-side entity data, not GPU resources.
+
+Internally it wraps a `Pool<Scene, SceneHandle>`:
+
+```
+SceneRegistry
+ └── Pool<Scene, SceneHandle>
+      └── Slot { Scene, generation }  →  SceneHandle
+```
+
+Typical lifecycle:
+
+```
+create()  →  SceneHandle
+                  │
+        get(handle)  →  Scene&
+                  │
+        release(handle)
+```
+
+Think: "Where do I create or look up a Scene by handle, without owning its
+lifetime directly?"
+
 ## Sprite
 
 A Sprite is a 2D renderable representation of an image, usually a rectangular region of a texture.
diff --git a/engine/include/sophia/application.hpp b/engine/include/sophia/application.hpp
index 88b333e..f7675b0 100644
--- a/engine/include/sophia/application.hpp
+++ b/engine/include/sophia/application.hpp
@@ -8,6 +8,7 @@
 #include <sophia/console/console_command_registry.hpp>
 #include <sophia/frame_info.hpp>
 #include <sophia/resource_registry_ref.hpp>
+#include <sophia/scene_registry.hpp>
 #include <sophia/types.hpp>
 #include <sophia/ui/debug_ui.hpp>
 #include <sophia/ui/panel_registry.hpp>
@@ -47,6 +48,7 @@ class Application {
 
   ResourceRegistryRef resources();
   PanelRegistry& panels() { return this->panelRegistry; }
+  SceneRegistry& scenes() { return this->sceneRegistry; }
   UI& ui() { return this->_ui; }
 
   DebugUI& debugUI() { return this->_debugUI; }
@@ -60,6 +62,7 @@ class Application {
   void drawMesh(MeshHandle handle, const glm::mat4& transform);
 
   /**
+   * !TEMP !TODO remove this func eventually
    * Chooses where the scene is rendered. An invalid handle (the default) means
    * the swapchain; a target created with
    * ResourceRegistryRef::create<RenderTarget>() redirects it offscreen, and the
@@ -78,6 +81,7 @@ class Application {
   std::unique_ptr<Impl> impl;
 
   PanelRegistry panelRegistry;
+  SceneRegistry sceneRegistry;
   UI _ui;
 
   DebugUI _debugUI;
diff --git a/engine/include/sophia/resource_registry_ref.hpp b/engine/include/sophia/resource_registry_ref.hpp
index 5823b63..34d4785 100644
--- a/engine/include/sophia/resource_registry_ref.hpp
+++ b/engine/include/sophia/resource_registry_ref.hpp
@@ -16,7 +16,6 @@ namespace sophia {
 
 class Mesh;
 class RenderTarget;
-class Scene;
 class ResourceRegistry;
 
 template <typename T>
@@ -32,11 +31,6 @@ struct ResourceTraits<RenderTarget> {
   using Handle = RenderTargetHandle;
 };
 
-template <>
-struct ResourceTraits<Scene> {
-  using Handle = SceneHandle;
-};
-
 class ResourceRegistryRef {
  public:
   template <typename T>
@@ -52,7 +46,6 @@ class ResourceRegistryRef {
   glm::vec2 getExtent(RenderTargetHandle handle) const;
 
   bool isAlive(RenderTargetHandle handle) const;
-  bool isAlive(SceneHandle handle) const;
 
   template <typename T>
   void release(typename ResourceTraits<T>::Handle handle);
@@ -70,8 +63,6 @@ class ResourceRegistryRef {
   RenderTargetHandle createResource(std::type_identity<RenderTarget>,
                                     u32 width = 1, u32 height = 1);
 
-  SceneHandle createResource(std::type_identity<Scene>);
-
   ResourceRegistry* registry;
 };
 
@@ -84,7 +75,4 @@ void ResourceRegistryRef::release<Mesh>(MeshHandle handle);
 template <>
 void ResourceRegistryRef::release<RenderTarget>(RenderTargetHandle handle);
 
-template <>
-void ResourceRegistryRef::release<Scene>(SceneHandle handle);
-
 }  // namespace sophia
diff --git a/engine/include/sophia/scene.hpp b/engine/include/sophia/scene.hpp
new file mode 100644
index 0000000..bbc1c70
--- /dev/null
+++ b/engine/include/sophia/scene.hpp
@@ -0,0 +1,21 @@
+#pragma once
+
+#include <entt/entt.hpp>
+
+namespace sophia {
+
+class Scene {
+ public:
+  Scene();
+  ~Scene();
+
+  // The camera a render request uses when it doesn't name one. Null until set.
+  entt::entity getActiveCamera() const { return activeCamera; }
+  void setActiveCamera(entt::entity camera) { activeCamera = camera; }
+
+ private:
+  entt::registry registry;
+  entt::entity activeCamera = entt::null;
+};
+
+}  // namespace sophia
diff --git a/engine/include/sophia/scene_registry.hpp b/engine/include/sophia/scene_registry.hpp
new file mode 100644
index 0000000..70e2739
--- /dev/null
+++ b/engine/include/sophia/scene_registry.hpp
@@ -0,0 +1,31 @@
+#pragma once
+
+#include <sophia/handles.hpp>
+#include <sophia/scene.hpp>
+#include <sophia/util/pool.hpp>
+
+namespace sophia {
+
+class SceneRegistry {
+ public:
+  SceneRegistry(const SceneRegistry&) = delete;
+  SceneRegistry& operator=(const SceneRegistry&) = delete;
+
+  SceneRegistry() = default;
+  ~SceneRegistry() = default;
+
+  SceneHandle create() { return pool.create(); }
+
+  const Scene& get(SceneHandle handle) const { return pool.get(handle); }
+  Scene& get(SceneHandle handle) { return pool.get(handle); }
+
+  void release(SceneHandle handle) { pool.release(handle); }
+  bool isAlive(SceneHandle handle) const { return pool.isAlive(handle); }
+
+  u32 size() const { return pool.size(); }
+
+ private:
+  Pool<Scene, SceneHandle> pool{"Scene"};
+};
+
+}  // namespace sophia
diff --git a/engine/include/sophia/ui/panel_registry.hpp b/engine/include/sophia/ui/panel_registry.hpp
index 09b3b87..b53b11c 100644
--- a/engine/include/sophia/ui/panel_registry.hpp
+++ b/engine/include/sophia/ui/panel_registry.hpp
@@ -6,6 +6,7 @@
 #include <sophia/ui/dock_layout.hpp>
 #include <sophia/ui/panel.hpp>
 #include <sophia/util/assert.hpp>
+#include <sophia/util/pool.hpp>
 #include <string_view>
 #include <typeinfo>
 #include <utility>
@@ -21,17 +22,17 @@ class PanelRegistry {
   PanelRegistry() = default;
   ~PanelRegistry() = default;
 
-  PanelHandle add(std::unique_ptr<Panel> panel);
+  PanelHandle add(std::unique_ptr<Panel> panel) {
+    return pool.add(std::move(panel));
+  }
 
   template <typename T, typename... Args>
   PanelHandle emplace(Args&&... args) {
     return add(std::make_unique<T>(std::forward<Args>(args)...));
   }
 
-  const Panel& get(PanelHandle handle) const;
-  Panel& get(PanelHandle handle) {
-    return const_cast<Panel&>(std::as_const(*this).get(handle));
-  }
+  const Panel& get(PanelHandle handle) const { return pool.get(handle); }
+  Panel& get(PanelHandle handle) { return pool.get(handle); }
 
   template <typename T>
   const T& get(PanelHandle handle) const {
@@ -46,19 +47,17 @@ class PanelRegistry {
     return const_cast<T&>(std::as_const(*this).template get<T>(handle));
   }
 
-  void remove(PanelHandle handle);
-  bool isValid(PanelHandle handle) const;
+  void remove(PanelHandle handle) { pool.release(handle); }
+  bool isValid(PanelHandle handle) const { return pool.isAlive(handle); }
 
   template <typename T>
   const T* find() const {
-    for (const Slot& slot : slots) {
-      if (slot.panel) {
-        if (const T* panel = dynamic_cast<const T*>(slot.panel.get())) {
-          return panel;
-        }
-      }
-    }
-    return nullptr;
+    const T* result = nullptr;
+    pool.findIf([&result](const Panel& panel) {
+      result = dynamic_cast<const T*>(&panel);
+      return result != nullptr;
+    });
+    return result;
   }
 
   template <typename T>
@@ -67,29 +66,22 @@ class PanelRegistry {
   }
 
   const Panel* find(std::string_view name) const {
-    for (const Slot& slot : slots) {
-      if (slot.panel && slot.panel->getName() == name) {
-        return slot.panel.get();
-      }
-    }
-    return nullptr;
+    return pool.findIf(
+        [name](const Panel& panel) { return panel.getName() == name; });
   }
 
   Panel* find(std::string_view name) {
     return const_cast<Panel*>(std::as_const(*this).find(name));
   }
 
-  u32 size() const;
+  u32 size() const { return pool.size(); }
   u32 visibleCount() const;
 
   std::vector<std::string_view> names() const {
     std::vector<std::string_view> result;
-    result.reserve(slots.size());
-    for (const Slot& slot : slots) {
-      if (slot.panel) {
-        result.push_back(slot.panel->getName());
-      }
-    }
+    result.reserve(pool.size());
+    pool.forEach(
+        [&result](const Panel& panel) { result.push_back(panel.getName()); });
     return result;
   }
 
@@ -101,13 +93,7 @@ class PanelRegistry {
   const DockLayout& getDefaultLayout() const { return defaultLayout; }
 
  private:
-  struct Slot {
-    std::unique_ptr<Panel> panel;
-    u32 generation = 0;
-  };
-
-  std::vector<Slot> slots;
-  std::vector<u32> freeList;
+  Pool<Panel, PanelHandle> pool{"Panel"};
   DockLayout defaultLayout;
 };
 
diff --git a/engine/src/resources/pools/pool.hpp b/engine/include/sophia/util/pool.hpp
similarity index 60%
rename from engine/src/resources/pools/pool.hpp
rename to engine/include/sophia/util/pool.hpp
index 99669bd..f5b8a53 100644
--- a/engine/src/resources/pools/pool.hpp
+++ b/engine/include/sophia/util/pool.hpp
@@ -8,7 +8,7 @@
 
 namespace sophia {
 
-template <typename T, typename HandleT>
+template <typename T, typename HandleType>
 class Pool {
  public:
   explicit Pool(const char* name) : name{name} {}
@@ -17,27 +17,29 @@ class Pool {
   Pool& operator=(const Pool&) = delete;
 
   template <typename... Args>
-  HandleT create(Args&&... args) {
-    auto item = std::make_unique<T>(std::forward<Args>(args)...);
+  HandleType create(Args&&... args) {
+    return add(std::make_unique<T>(std::forward<Args>(args)...));
+  }
 
+  HandleType add(std::unique_ptr<T> item) {
     if (!freeList.empty()) {
       u32 index = freeList.back();
       freeList.pop_back();
       slots[index].item = std::move(item);
-      return HandleT{index, slots[index].generation};
+      return HandleType{index, slots[index].generation};
     }
 
     slots.push_back(Slot{std::move(item), 0});
-    return HandleT{static_cast<u32>(slots.size() - 1), 0};
+    return HandleType{static_cast<u32>(slots.size() - 1), 0};
   }
 
-  T& get(HandleT handle) {
+  T& get(HandleType handle) {
     return const_cast<T&>(std::as_const(*this).get(handle));
   }
 
-  const T& get(HandleT handle) const { return *validate(handle).item; }
+  const T& get(HandleType handle) const { return *validate(handle).item; }
 
-  void release(HandleT handle) {
+  void release(HandleType handle) {
     validate(handle);
 
     Slot& slot = slots[handle.index];
@@ -46,12 +48,14 @@ class Pool {
     freeList.push_back(handle.index);
   }
 
-  bool isAlive(HandleT handle) const {
+  bool isAlive(HandleType handle) const {
     return handle.isValid() && handle.index < slots.size() &&
            slots[handle.index].generation == handle.generation &&
            slots[handle.index].item != nullptr;
   }
 
+  u32 size() const { return static_cast<u32>(slots.size() - freeList.size()); }
+
   template <typename Fn>
   void forEach(Fn&& fn) {
     for (Slot& slot : slots) {
@@ -61,6 +65,31 @@ class Pool {
     }
   }
 
+  template <typename Fn>
+  void forEach(Fn&& fn) const {
+    for (const Slot& slot : slots) {
+      if (slot.item) {
+        fn(*slot.item);
+      }
+    }
+  }
+
+  template <typename Predicate>
+  T* findIf(Predicate&& predicate) {
+    return const_cast<T*>(
+        std::as_const(*this).findIf(std::forward<Predicate>(predicate)));
+  }
+
+  template <typename Predicate>
+  const T* findIf(Predicate&& predicate) const {
+    for (const Slot& slot : slots) {
+      if (slot.item && predicate(*slot.item)) {
+        return slot.item.get();
+      }
+    }
+    return nullptr;
+  }
+
  private:
   static constexpr u32 GENERATION_MASK = (1u << 12) - 1;
 
@@ -69,7 +98,7 @@ class Pool {
     u32 generation = 0;
   };
 
-  const Slot& validate(HandleT handle) const {
+  const Slot& validate(HandleType handle) const {
     SOPHIA_ASSERT(handle.isValid(), "invalid handle:", name);
     SOPHIA_ASSERT(handle.index < slots.size(), name,
                   "handle index out of range:", handle.index);
diff --git a/engine/src/render_context.cpp b/engine/src/render_context.cpp
index 76296c6..c07dd0e 100644
--- a/engine/src/render_context.cpp
+++ b/engine/src/render_context.cpp
@@ -5,6 +5,8 @@
 #include <sophia/util/logger.hpp>
 #include <stdexcept>
 
+#include "rendering/access.hpp"
+
 namespace sophia {
 
 RenderContext::RenderContext(Window& window, Device& device)
@@ -80,8 +82,7 @@ void RenderContext::endFrame() {
   vk::Semaphore waitSemaphore = frame.imageAvailable.get();
   vk::Semaphore signalSemaphore =
       this->renderFinishedSemaphores.at(this->currentImageIndex).get();
-  vk::PipelineStageFlags waitStage =
-      vk::PipelineStageFlagBits::eColorAttachmentOutput;
+  vk::PipelineStageFlags waitStage = SWAPCHAIN_ACQUIRE_STAGE;
   vk::CommandBuffer commandBuffer = frame.commandBuffer;
 
   vk::SubmitInfo submitInfo{};
diff --git a/engine/src/render_context.hpp b/engine/src/render_context.hpp
index 34e7ac1..afe4728 100644
--- a/engine/src/render_context.hpp
+++ b/engine/src/render_context.hpp
@@ -31,14 +31,8 @@ class RenderContext {
   vk::CommandBuffer beginFrame();
   void endFrame();
 
-  void transitionCurrentImage(vk::CommandBuffer commandBuffer,
-                              vk::ImageLayout newLayout) const {
-    this->swapchain->getImage(static_cast<int>(this->currentImageIndex))
-        .transitionLayout(commandBuffer, newLayout);
-  }
-  vk::ImageView getCurrentImageView() const {
-    return this->swapchain->getImageView(
-        static_cast<int>(this->currentImageIndex));
+  Image& getCurrentImage() const {
+    return this->swapchain->getImage(static_cast<int>(this->currentImageIndex));
   }
 
   vk::Extent2D getExtent() const { return this->swapchain->getExtent(); }
diff --git a/engine/src/resources/pools/render_target_pool.hpp b/engine/src/resources/pools/render_target_pool.hpp
index ff7ca0f..63a6afb 100644
--- a/engine/src/resources/pools/render_target_pool.hpp
+++ b/engine/src/resources/pools/render_target_pool.hpp
@@ -1,10 +1,10 @@
 #pragma once
 
 #include <sophia/handles.hpp>
+#include <sophia/util/pool.hpp>
 
 #include "device.hpp"
 #include "render_target.hpp"
-#include "resources/pools/pool.hpp"
 
 namespace sophia {
 
diff --git a/engine/src/resources/resource_registry.hpp b/engine/src/resources/resource_registry.hpp
index 6dc5629..1acb28d 100644
--- a/engine/src/resources/resource_registry.hpp
+++ b/engine/src/resources/resource_registry.hpp
@@ -1,12 +1,11 @@
 #pragma once
 
 #include <sophia/handles.hpp>
+#include <sophia/util/pool.hpp>
 
 #include "device.hpp"
 #include "mesh.hpp"
-#include "resources/pools/pool.hpp"
 #include "resources/pools/render_target_pool.hpp"
-#include "scene.hpp"
 
 namespace sophia {
 
@@ -21,7 +20,6 @@ class ResourceRegistry {
   Device& device;
   Pool<Mesh, MeshHandle> meshPool{"Mesh"};
   RenderTargetPool renderTargetPool;
-  Pool<Scene, SceneHandle> scenePool{"Scene"};
   // TexturePool textures;
   // MaterialPool materials;
 };
diff --git a/engine/src/resources/resource_registry_ref.cpp b/engine/src/resources/resource_registry_ref.cpp
index 5e24d7b..6d963a8 100644
--- a/engine/src/resources/resource_registry_ref.cpp
+++ b/engine/src/resources/resource_registry_ref.cpp
@@ -24,11 +24,6 @@ void ResourceRegistryRef::release<RenderTarget>(RenderTargetHandle handle) {
   registry->renderTargetPool.release(handle);
 }
 
-template <>
-void ResourceRegistryRef::release<Scene>(SceneHandle handle) {
-  registry->scenePool.release(handle);
-}
-
 MeshHandle ResourceRegistryRef::createResource(
     std::type_identity<Mesh>, std::vector<CanvasVertex> vertices,
     std::vector<u32> indices) {
@@ -47,10 +42,6 @@ RenderTargetHandle ResourceRegistryRef::createResource(
   return registry->renderTargetPool.create(width, height);
 }
 
-SceneHandle ResourceRegistryRef::createResource(std::type_identity<Scene>) {
-  return registry->scenePool.create();
-}
-
 void ResourceRegistryRef::requestResize(RenderTargetHandle handle, u32 width,
                                         u32 height) {
   registry->renderTargetPool.get(handle).requestResize(width, height);
@@ -65,8 +56,4 @@ bool ResourceRegistryRef::isAlive(RenderTargetHandle handle) const {
   return registry->renderTargetPool.isAlive(handle);
 }
 
-bool ResourceRegistryRef::isAlive(SceneHandle handle) const {
-  return registry->scenePool.isAlive(handle);
-}
-
 }  // namespace sophia
diff --git a/engine/src/scene.cpp b/engine/src/scene.cpp
index 865868f..375424b 100644
--- a/engine/src/scene.cpp
+++ b/engine/src/scene.cpp
@@ -1,6 +1,5 @@
-#include "scene.hpp"
-
 #include <sophia/components.hpp>
+#include <sophia/scene.hpp>
 #include <sophia/util/logger.hpp>
 
 namespace sophia {
diff --git a/engine/src/scene.hpp b/engine/src/scene.hpp
deleted file mode 100644
index ed40054..0000000
--- a/engine/src/scene.hpp
+++ /dev/null
@@ -1,16 +0,0 @@
-#pragma once
-
-#include <entt/entt.hpp>
-
-namespace sophia {
-
-class Scene {
- public:
-  Scene();
-  ~Scene();
-
- private:
-  entt::registry registry;
-};
-
-}  // namespace sophia
diff --git a/engine/src/swapchain.hpp b/engine/src/swapchain.hpp
index 8168700..0422aec 100644
--- a/engine/src/swapchain.hpp
+++ b/engine/src/swapchain.hpp
@@ -23,9 +23,6 @@ class Swapchain {
   Image& getImage(int index) const { return *this->images.at(index); }
   Image& getDepthImage(int index) const { return *this->depthImages.at(index); }
 
-  vk::ImageView getImageView(int index) const {
-    return this->images.at(index)->getView();
-  }
   vk::ImageView getDepthImageView(int index) const {
     return this->depthImages.at(index)->getView();
   }
diff --git a/engine/src/ui/panel_registry.cpp b/engine/src/ui/panel_registry.cpp
index 5b34ea9..f372ffd 100644
--- a/engine/src/ui/panel_registry.cpp
+++ b/engine/src/ui/panel_registry.cpp
@@ -1,88 +1,23 @@
 #include <sophia/ui/panel_registry.hpp>
-#include <sophia/util/assert.hpp>
 
 namespace sophia {
 
-namespace {
-constexpr u32 GENERATION_MASK = (1u << 12) - 1;
-}  // namespace
-
-PanelHandle PanelRegistry::add(std::unique_ptr<Panel> panel) {
-  if (!freeList.empty()) {
-    u32 index = freeList.back();
-    freeList.pop_back();
-    slots[index].panel = std::move(panel);
-    return PanelHandle{index, slots[index].generation};
-  }
-
-  slots.push_back(Slot{std::move(panel), 0});
-  return PanelHandle{static_cast<u32>(slots.size() - 1), 0};
-}
-
-const Panel& PanelRegistry::get(PanelHandle handle) const {
-  SOPHIA_ASSERT(handle.isValid(), "invalid PanelHandle");
-  SOPHIA_ASSERT(handle.index < slots.size(),
-                "PanelHandle index out of range:", handle.index);
-
-  const Slot& slot = slots[handle.index];
-  SOPHIA_ASSERT(slot.generation == handle.generation,
-                "stale PanelHandle (generation mismatch):", handle.index);
-  SOPHIA_ASSERT(slot.panel != nullptr,
-                "PanelHandle refers to a removed panel:", handle.index);
-  return *slot.panel;
-}
-
-void PanelRegistry::remove(PanelHandle handle) {
-  SOPHIA_ASSERT(handle.isValid(), "invalid PanelHandle");
-  SOPHIA_ASSERT(handle.index < slots.size(),
-                "PanelHandle index out of range:", handle.index);
-
-  Slot& slot = slots[handle.index];
-  SOPHIA_ASSERT(slot.generation == handle.generation,
-                "stale PanelHandle (generation mismatch):", handle.index);
-  SOPHIA_ASSERT(slot.panel != nullptr,
-                "PanelHandle already removed:", handle.index);
-
-  slot.panel.reset();
-  slot.generation = (slot.generation + 1) & GENERATION_MASK;
-  freeList.push_back(handle.index);
-}
-
-bool PanelRegistry::isValid(PanelHandle handle) const {
-  if (!handle.isValid() || handle.index >= slots.size()) {
-    return false;
-  }
-
-  const Slot& slot = slots[handle.index];
-  return slot.generation == handle.generation && slot.panel != nullptr;
-}
-
-u32 PanelRegistry::size() const {
-  u32 count = 0;
-  for (const Slot& slot : slots) {
-    if (slot.panel) {
-      count++;
-    }
-  }
-  return count;
-}
-
 u32 PanelRegistry::visibleCount() const {
   u32 count = 0;
-  for (const Slot& slot : slots) {
-    if (slot.panel && slot.panel->isVisible()) {
+  pool.forEach([&count](const Panel& panel) {
+    if (panel.isVisible()) {
       count++;
     }
-  }
+  });
   return count;
 }
 
 void PanelRegistry::update(const FrameInfo& frameInfo) {
-  for (auto& slot : slots) {
-    if (slot.panel && slot.panel->isVisible()) {
-      slot.panel->draw(frameInfo);
+  pool.forEach([&frameInfo](Panel& panel) {
+    if (panel.isVisible()) {
+      panel.draw(frameInfo);
     }
-  }
+  });
 }
 
 }  // namespace sophia