feat(shadertoy): add streaming partial input, visibility optimization, host styling

Shadertoy server improvements:
- Add ontoolinputpartial handler to show code preview during generation
- Add IntersectionObserver to pause/play shader based on visibility
- Apply host style variables (theme, colors, fonts)
- Add border-radius with fullscreen mode support
- Use gradient background and ghost text color for code preview

Skill documentation updates:
- Add streaming partial input section with use cases
- Add visibility-based resource management pattern
- Add fullscreen mode API and CSS patterns
- Expand host styling with CSS variable usage examples

examples/shadertoy-server/src/mcp-app.css

@@ -11,6 +11,12 @@ html, body {
   width: 100%;
   height: 100%;
   min-height: 400px;
+  border-radius: var(--border-radius-lg);
+  overflow: hidden;
+}
+
+.main.fullscreen {
+  border-radius: 0;
 }
 
 #canvas {
@@ -19,6 +25,34 @@ html, body {
   display: block;
 }
 
+#canvas.hidden {
+  display: none;
+}
+
+#code-preview {
+  display: none;
+  width: 100%;
+  height: 100%;
+  margin: 0;
+  padding: 16px;
+  box-sizing: border-box;
+  overflow: auto;
+  background: linear-gradient(
+    135deg,
+    var(--color-background-secondary) 0%,
+    var(--color-background-tertiary) 100%
+  );
+  color: var(--color-text-ghost);
+  font-family: var(--font-mono);
+  font-size: var(--font-text-xs-size);
+  line-height: var(--font-text-xs-line-height);
+  white-space: pre-wrap;
+}
+
+#code-preview.visible {
+  display: block;
+}
+
 /* Fullscreen button */
 .fullscreen-btn {
   position: absolute;

examples/shadertoy-server/src/mcp-app.ts

@@ -1,7 +1,12 @@
 /**
  * ShaderToy renderer MCP App using ShaderToyLite.js
  */
-import { App, type McpUiHostContext } from "@modelcontextprotocol/ext-apps";
+import {
+  App,
+  type McpUiHostContext,
+  applyHostStyleVariables,
+  applyDocumentTheme,
+} from "@modelcontextprotocol/ext-apps";
 import "./global.css";
 import "./mcp-app.css";
 import ShaderToyLite, {
@@ -34,6 +39,7 @@ const log = {
 // Get element references
 const mainEl = document.querySelector(".main") as HTMLElement;
 const canvas = document.getElementById("canvas") as HTMLCanvasElement;
+const codePreview = document.getElementById("code-preview") as HTMLPreElement;
 const fullscreenBtn = document.getElementById(
   "fullscreen-btn",
 ) as HTMLButtonElement;
@@ -49,8 +55,12 @@ function resizeCanvas() {
 resizeCanvas();
 window.addEventListener("resize", resizeCanvas);
 
-// Handle host context changes (display mode)
+// Handle host context changes (display mode, styling)
 function handleHostContextChanged(ctx: McpUiHostContext) {
+  // Apply host styling
+  if (ctx.theme) applyDocumentTheme(ctx.theme);
+  if (ctx.styles?.variables) applyHostStyleVariables(ctx.styles.variables);
+
   // Note: We ignore safeAreaInsets to maximize shader display area
 
   // Show fullscreen button if available (only update if field is present)
@@ -112,9 +122,22 @@ app.onteardown = async () => {
   return {};
 };
 
+app.ontoolinputpartial = (params) => {
+  // Show code preview, hide canvas
+  codePreview.classList.add("visible");
+  canvas.classList.add("hidden");
+  const code = params.arguments?.fragmentShader;
+  codePreview.textContent = typeof code === "string" ? code : "";
+  codePreview.scrollTop = codePreview.scrollHeight;
+};
+
 app.ontoolinput = (params) => {
   log.info("Received shader input");
 
+  // Hide code preview, show canvas
+  codePreview.classList.remove("visible");
+  canvas.classList.remove("hidden");
+
   if (!isShaderInput(params.arguments)) {
     log.error("Invalid tool input");
     return;
@@ -162,6 +185,18 @@ app.onerror = log.error;
 
 app.onhostcontextchanged = handleHostContextChanged;
 
+// Pause/resume shader based on visibility
+const observer = new IntersectionObserver((entries) => {
+  entries.forEach((entry) => {
+    if (entry.isIntersecting) {
+      shaderToy?.play();
+    } else {
+      shaderToy?.pause();
+    }
+  });
+});
+observer.observe(mainEl);
+
 // Connect to host
 app.connect().then(() => {
   log.info("Connected to host");