diff --git a/sandbox/main.cpp b/sandbox/main.cpp
index af1b5ce..8ab5895 100644
--- a/sandbox/main.cpp
+++ b/sandbox/main.cpp
@@ -1,18 +1,295 @@
 #define GLFW_INCLUDE_VULKAN
 #include <GLFW/glfw3.h>
+#include <imgui.h>
 
 #include <algorithm>
 #include <array>
+#include <chrono>
 #include <cmath>
+#include <cstddef>
 #include <cstdint>
 #include <cstdio>
 #include <cstdlib>
+#include <glm/glm.hpp>
+#include <glm/gtc/matrix_transform.hpp>
 #include <glm/mat4x4.hpp>
 #include <glm/vec4.hpp>
+#include <iostream>
+#include <map>
+#include <memory>
+#include <optional>
+#include <set>
+#include <sophia/application.hpp>
+#include <sophia/canvas.hpp>
+#include <sophia/console/console_command_registry.hpp>
+#include <sophia/frame_info.hpp>
+#include <sophia/math.hpp>
+#include <sophia/resource_registry_ref.hpp>
+#include <sophia/scene_registry.hpp>
+#include <sophia/scene_view.hpp>
+#include <sophia/scene_view_registry.hpp>
+#include <sophia/types.hpp>
+#include <sophia/ui/debug_ui.hpp>
+#include <sophia/ui/panel_registry.hpp>
+#include <sophia/ui/ui.hpp>
+#include <sophia/util/logger.hpp>
+#include <string>
+#include <tracy/Tracy.hpp>
+#include <utility>
 #include <vector>
+#include <vulkan/vulkan.hpp>
+
+#include "renderer/imgui_renderer.hpp"
+#include "renderer/model_render_system.hpp"
+#include "renderer/render_context.hpp"
+#include "renderer/render_graph.hpp"
+#include "renderer/scene_renderer.hpp"
+#include "resources/mesh.hpp"
+#include "resources/render_target.hpp"
+#include "resources/resource_registry.hpp"
+#include "vulkan/buffer.hpp"
+#include "vulkan/device.hpp"
+#include "vulkan/pipelines/graphics_pipeline.hpp"
+#include "vulkan/shader.hpp"
+#include "window.hpp"
 
 constexpr uint32_t WIDTH = 1280;
 constexpr uint32_t HEIGHT = 720;
-constexpr const char* NAME = "";
+constexpr const char* NAME = "sandbox";
 
-int main() { return EXIT_SUCCESS; }
+constexpr sophia::ClearColor CLEAR_COLOR = {0.01f, 0.01f, 0.02f, 1.0f};
+
+bool hasFlag(sophia::ClearFlags flags, sophia::ClearFlags flag) {
+  return (static_cast<sophia::u8>(flags) & static_cast<sophia::u8>(flag)) != 0;
+}
+
+int main(int argc, const char** argv) {
+  std::vector<std::string> args;
+  args.assign(argv, argv + argc);
+
+  std::cout << __FILE__ << "::" << __LINE__ << '\n';
+
+  sophia::Window window{WIDTH, HEIGHT, NAME};
+  sophia::Device device{&window};
+  sophia::RenderContext renderContext{window, device};
+  sophia::ResourceRegistry resourceRegistry{
+      device, renderContext.getImageFormat()};  // remove?
+
+  // remove?
+  std::vector<std::unique_ptr<sophia::Mesh>> meshes;
+
+  // remove?
+  std::vector<sophia::ModelRenderSystem::MeshInstance> drawCalls;
+
+  // todo: figure out which to remove
+  sophia::PanelRegistry panelRegistry;
+  sophia::SceneRegistry sceneRegistry;
+  sophia::SceneViewRegistry sceneViewRegistry;
+  sophia::ConsoleCommandRegistry consoleCommandRegistry;
+
+  sophia::DebugUI debugUI{panelRegistry, consoleCommandRegistry};
+  debugUI.showFrameStats(true);
+
+  sophia::ModelRenderSystem modelRenderSystem{device, renderContext};
+  sophia::SceneRenderer sceneRenderer{sceneRegistry, resourceRegistry, device,
+                                      renderContext.getImageFormat()};
+  sophia::ImGuiRenderer imguiRenderer{
+      window, device, renderContext.getImageFormat(),
+      renderContext.getImageCount(), resourceRegistry};
+
+  consoleCommandRegistry.registerCommand(
+      "reset_layout", "Restore the default panel layout",
+      [&imguiRenderer](const std::vector<std::string>&) {
+        imguiRenderer.resetLayout();
+        return std::string{"Layout reset"};
+      });
+
+  auto& meshPool = resourceRegistry.meshPool;
+  auto& renderTargetPool = resourceRegistry.renderTargetPool;
+
+  imguiRenderer.setDefaultLayout(panelRegistry.getDefaultLayout());
+
+  // Views already warned about, so each warns once.
+  std::set<sophia::SceneViewHandle> viewsWithoutCamera;
+  std::set<sophia::SceneViewHandle> viewsOverwritingOthers;
+
+  auto startTime = std::chrono::high_resolution_clock::now();
+  auto currentTime = startTime;
+  sophia::u32 frameIndex = 0;
+
+  while (!window.shouldClose()) {
+    glfwPollEvents();
+
+    auto newTime = std::chrono::high_resolution_clock::now();
+    double deltaTime =
+        std::chrono::duration<double>(newTime - currentTime).count();
+    currentTime = newTime;
+
+    double elapsedTime =
+        std::chrono::duration<double>(currentTime - startTime).count();
+
+    // Resizing waits for the GPU, so it has to happen before any of this
+    // frame's work (or ImGui's references to the targets) is recorded.
+    renderTargetPool.applyPendingResizes();
+
+    vk::Extent2D extent = renderContext.getExtent();
+    sophia::FrameInfo frameInfo{frameIndex, elapsedTime, deltaTime,
+                                glm::vec2(static_cast<float>(extent.width),
+                                          static_cast<float>(extent.height))};
+
+    // Canvas draws in window pixels, origin at the center.
+    // TODO: replace with Debug/Gizmos drawn into scene views through their
+    // cameras.
+    glm::mat4 canvasProjection =
+        glm::ortho(-frameInfo.currentFramebufferExtent.x / 2.f,
+                   frameInfo.currentFramebufferExtent.x / 2.f,
+                   -frameInfo.currentFramebufferExtent.y / 2.f,
+                   frameInfo.currentFramebufferExtent.y / 2.f);
+
+    vk::CommandBuffer commandBuffer = renderContext.beginFrame();
+    if (!commandBuffer) {
+      continue;
+    }
+
+    imguiRenderer.beginFrame();
+    sceneRenderer.beginFrame(renderContext.getFrameIndex());
+
+    panelRegistry.update(frameInfo);
+
+    std::vector<sophia::ModelRenderSystem::MeshInstance> instances;
+    instances.reserve(meshes.size() + drawCalls.size());
+    for (const std::unique_ptr<sophia::Mesh>& mesh : meshes) {
+      instances.push_back({mesh.get(), glm::mat4{1.f}});
+    }
+    instances.insert(instances.end(), drawCalls.begin(), drawCalls.end());
+    drawCalls.clear();
+
+    sophia::RenderGraph graph{renderContext.getTracyContext()};
+    sophia::ImageRef backbuffer = graph.importImage(
+        renderContext.getCurrentImage(), sophia::Access::Present);
+
+    struct ViewTarget {
+      sophia::ImageRef color;
+      sophia::ImageRef depth;
+    };
+    std::map<sophia::RenderTargetHandle, ViewTarget> viewTargets;
+    // Views without a target render straight into the backbuffer.
+    std::optional<ViewTarget> swapchainTarget;
+    for (sophia::SceneViewHandle handle : sceneViewRegistry.GetRenderQueue()) {
+      const sophia::SceneView& view = sceneViewRegistry.peek(handle);
+      bool toSwapchain = !view.target.isValid();
+      if (!sceneRegistry.isAlive(view.scene) ||
+          !sceneRegistry.get(view.scene).isVisible() ||
+          (!toSwapchain && !renderTargetPool.isAlive(view.target))) {
+        continue;
+      }
+
+      ViewTarget target;
+      vk::Extent2D targetExtent;
+      // Whether this is the first view this frame to render to its target.
+      bool firstOnTarget = false;
+      if (toSwapchain) {
+        firstOnTarget = !swapchainTarget;
+        if (!swapchainTarget) {
+          swapchainTarget = {
+              backbuffer,
+              graph.importImage(renderContext.getCurrentDepthImage(),
+                                sophia::Access::DepthWrite)};
+        }
+        target = *swapchainTarget;
+        targetExtent = renderContext.getExtent();
+      } else {
+        sophia::RenderTarget& renderTarget = renderTargetPool.get(view.target);
+        auto [it, inserted] = viewTargets.try_emplace(view.target);
+        firstOnTarget = inserted;
+        if (inserted) {
+          it->second = {graph.importImage(renderTarget.getImage(),
+                                          sophia::Access::SampledRead),
+                        graph.importImage(renderTarget.getDepthImage(),
+                                          sophia::Access::DepthWrite)};
+        }
+        target = it->second;
+        targetExtent = renderTarget.getExtent();
+      }
+
+      if (!firstOnTarget &&
+          hasFlag(view.clearFlags, sophia::ClearFlags::Color) &&
+          viewsOverwritingOthers.insert(handle).second) {
+        sophia::log::warning(
+            "scene view clears its target after another view already "
+            "rendered to it this frame, hiding that view (give it clearFlags "
+            "without Color, or render it first with a lower priority)");
+      }
+
+      const sophia::vec4& color = view.clearColor;
+      graph.addPass(
+          "scene view " + std::to_string(handle.index),
+          [&](sophia::RenderGraph::PassBuilder& pass) {
+            pass.writeColor(target.color,
+                            hasFlag(view.clearFlags, sophia::ClearFlags::Color)
+                                ? vk::AttachmentLoadOp::eClear
+                                : vk::AttachmentLoadOp::eLoad,
+                            {color.r, color.g, color.b, color.a});
+            pass.writeDepth(target.depth,
+                            hasFlag(view.clearFlags, sophia::ClearFlags::Depth)
+                                ? vk::AttachmentLoadOp::eClear
+                                : vk::AttachmentLoadOp::eLoad);
+          },
+          [&sceneRenderer, &sceneRegistry, &sceneViewRegistry,
+           &viewsWithoutCamera, handle,
+           targetExtent](vk::CommandBuffer commandBuffer) {
+            ZoneScopedN("scene view pass");
+            const sophia::SceneView& view = sceneViewRegistry.peek(handle);
+            sophia::Entity camera =
+                view.camera ? view.camera
+                            : sceneRegistry.get(view.scene).getActiveCamera();
+            // No camera to look through: the target is just cleared.
+            if (!camera) {
+              if (viewsWithoutCamera.insert(handle).second) {
+                sophia::log::warning(
+                    "scene view has no camera and its scene has no active "
+                    "camera; it will only be cleared (see "
+                    "Scene::createCamera)");
+              }
+              return;
+            }
+            sceneRenderer.render(commandBuffer, view, camera, targetExtent);
+          });
+    }
+
+    graph.addPass(
+        "main",
+        [&](sophia::RenderGraph::PassBuilder& pass) {
+          // Keep what scene views drew into the backbuffer.
+          pass.writeColor(backbuffer,
+                          swapchainTarget ? vk::AttachmentLoadOp::eLoad
+                                          : vk::AttachmentLoadOp::eClear,
+                          CLEAR_COLOR);
+          for (const auto& [handle, target] : viewTargets) {
+            pass.sample(target.color);
+          }
+        },
+        [&](vk::CommandBuffer commandBuffer) {
+          ZoneScopedN("main pass");
+          modelRenderSystem.render(commandBuffer, instances, canvasProjection);
+
+          imguiRenderer.endFrame(commandBuffer);
+        });
+
+    graph.execute(commandBuffer);
+
+    renderContext.endFrame();
+    FrameMark;
+
+    frameIndex++;
+  }
+
+  device.waitIdle();
+
+  auto endTime = std::chrono::high_resolution_clock::now();
+  double totalRuntime =
+      std::chrono::duration<double>(endTime - startTime).count();
+  sophia::log::info("Application ran for {:.2f}s", totalRuntime);
+
+  return EXIT_SUCCESS;
+}