feat: add example gallery with auto-generated screenshots (#253)

* feat: add script to generate 300x300 grid-cell.png screenshots for examples

- Add generate-grid-screenshots.spec.ts Playwright test to capture screenshots
- Add npm run generate:screenshots command (Docker-based for Santa compatibility)
- Add sharp dependency for image resizing with centered-fill mode
- Generate grid-cell.png for 14 example servers (only React for basic-server-* series)

The screenshots are 300x300 PNG images cropped with centered fill mode,
suitable for use in a grid layout showcasing the examples.

* docs: add example gallery grid to README

Add a 3-column visual grid showcasing 14 example MCP Apps with:
- Thumbnail screenshots (300x300 grid-cell.png)
- Clickable links to example directories
- Hover tooltips with brief descriptions

Organized by visual impact: 3D/WebGL examples first, then
visualizations, charts, monitoring, and starter templates.

* fix: use aspect-fit instead of crop for screenshots

Change from fit: 'cover' (crops) to fit: 'contain' (letterbox)
so the full app content is visible without cropping.

* feat: improve screenshot generation

- Constrain viewport to 500px width for consistent rendering
- Wait 5 seconds for full app load (tiles, animations, data)
- Screenshot just the inner iframe (no extra whitespace)
- Save both screenshot.png (full-size) and grid-cell.png (300x300 thumbnail)
- Use contain mode to preserve aspect ratio

* fix: use cover mode with top alignment for grid thumbnails

No letterboxing - crops to fill 300x300, aligned to top so headers
and important content are always visible.

* feat: improve screenshot gallery

- Remove integration-server from gallery (it's for E2E testing only)
- Add 30s extra wait for Map and Video servers to load fully
- Improve Three.js default scene: isometric rotation + better lighting
- Update README: Starter Templates row with links to all framework variants
  (React, Vue, Svelte, Preact, Solid, Vanilla JS)
- Regenerate all screenshots with updated settings

* fix: improve README gallery layout

- Fix uneven column widths by using minimal separator
- Move Starter Templates to separate 2-cell table with description
- Add screenshot.png to top of each example README (13 examples)
- Shorten tooltips for cleaner table

* revert to document.write again; cesiumjs doesn't like srcdoc, period.

* fix: map-server screenshot now renders properly

- Merged ochafik/post-fixes which reverts sandbox from srcdoc to document.write
  (CesiumJS doesn't work with srcdoc iframes)
- Fixed map-server name in screenshot test ('Map Server' not 'CesiumJS Map Server')
- Simplified screenshot generation script (removed complex debugging code)
- Increased map-server wait time to 45s for reliable tile loading
- Regenerated all 13 screenshots

* fix: remove redundant screenshots from READMEs

Remove the simple \![Screenshot](screenshot.png) line from READMEs that
already had nicer HTML table screenshots. Keep it only for examples
that didn't have existing screenshots.

* docs: move gallery to Examples section

- Move screenshot gallery from top of README to Examples section
- Remove redundant list of basic examples (now shown visually in gallery)
- Clean up duplicate run instructions

* fix: remove empty header row from starter templates table

* fix: remove empty header rows from both tables

* fix: add prettier-ignore to prevent table header expansion

* feat: use custom screenshot for video-resource-server

- Use better screenshot from PR #253 comment showing actual video playback
- Skip video-resource-server in screenshot generation script
- Add SKIP_SERVERS set for manually maintained screenshots

* fix: revert unrelated map-server name change

* fix: use correct server name 'CesiumJS Map Server' in screenshot test

README.md

@@ -56,19 +56,28 @@ Or edit your `package.json` manually:
 
 ## Examples
 
-Start with these foundational examples to learn the SDK:
+<!-- prettier-ignore-start -->
+| | | |
+|:---:|:---:|:---:|
+| [![Map](examples/map-server/grid-cell.png "Interactive 3D globe viewer using CesiumJS")](examples/map-server) | [![Three.js](examples/threejs-server/grid-cell.png "Interactive 3D scene renderer")](examples/threejs-server) | [![ShaderToy](examples/shadertoy-server/grid-cell.png "Real-time GLSL shader renderer")](examples/shadertoy-server) |
+| [**Map**](examples/map-server) | [**Three.js**](examples/threejs-server) | [**ShaderToy**](examples/shadertoy-server) |
+| [![Sheet Music](examples/sheet-music-server/grid-cell.png "ABC notation to sheet music")](examples/sheet-music-server) | [![Wiki Explorer](examples/wiki-explorer-server/grid-cell.png "Wikipedia link graph visualization")](examples/wiki-explorer-server) | [![Cohort Heatmap](examples/cohort-heatmap-server/grid-cell.png "Customer retention heatmap")](examples/cohort-heatmap-server) |
+| [**Sheet Music**](examples/sheet-music-server) | [**Wiki Explorer**](examples/wiki-explorer-server) | [**Cohort Heatmap**](examples/cohort-heatmap-server) |
+| [![Scenario Modeler](examples/scenario-modeler-server/grid-cell.png "SaaS business projections")](examples/scenario-modeler-server) | [![Budget Allocator](examples/budget-allocator-server/grid-cell.png "Interactive budget allocation")](examples/budget-allocator-server) | [![Customer Segmentation](examples/customer-segmentation-server/grid-cell.png "Scatter chart with clustering")](examples/customer-segmentation-server) |
+| [**Scenario Modeler**](examples/scenario-modeler-server) | [**Budget Allocator**](examples/budget-allocator-server) | [**Customer Segmentation**](examples/customer-segmentation-server) |
+| [![System Monitor](examples/system-monitor-server/grid-cell.png "Real-time OS metrics")](examples/system-monitor-server) | [![Transcript](examples/transcript-server/grid-cell.png "Live speech transcription")](examples/transcript-server) | [![Video Resource](examples/video-resource-server/grid-cell.png "Binary video via MCP resources")](examples/video-resource-server) |
+| [**System Monitor**](examples/system-monitor-server) | [**Transcript**](examples/transcript-server) | [**Video Resource**](examples/video-resource-server) |
 
-- [`examples/basic-server-vanillajs`](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-server-vanillajs) — MCP server + MCP App using vanilla JS
+### Starter Templates
-- [`examples/basic-server-react`](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-server-react) — MCP server + MCP App using [React](https://github.com/facebook/react)
+
-- [`examples/basic-server-vue`](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-server-vue) — MCP server + MCP App using [Vue](https://github.com/vuejs/vue)
+| | |
-- [`examples/basic-server-svelte`](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-server-svelte) — MCP server + MCP App using [Svelte](https://github.com/sveltejs/svelte)
+|:---:|:---|
-- [`examples/basic-server-preact`](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-server-preact) — MCP server + MCP App using [Preact](https://github.com/preactjs/preact)
+| [![Basic](examples/basic-server-react/grid-cell.png "Starter template")](examples/basic-server-react) | The same app built with different frameworks — pick your favorite!<br><br>[React](examples/basic-server-react) · [Vue](examples/basic-server-vue) · [Svelte](examples/basic-server-svelte) · [Preact](examples/basic-server-preact) · [Solid](examples/basic-server-solid) · [Vanilla JS](examples/basic-server-vanillajs) |
-- [`examples/basic-server-solid`](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-server-solid) — MCP server + MCP App using [Solid](https://github.com/solidjs/solid)
+<!-- prettier-ignore-end -->
-- [`examples/basic-host`](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples/basic-host) — MCP host application supporting MCP Apps
 
 The [`examples/`](https://github.com/modelcontextprotocol/ext-apps/tree/main/examples) directory contains additional demo apps showcasing real-world use cases.
 
-To run all examples together:
+To run all examples:
 
 ```bash
 npm install

examples/basic-server-react/README.md

@@ -1,5 +1,7 @@
 # Example: Basic Server (React)
 
+![Screenshot](screenshot.png)
+
 An MCP App example with a React UI.
 
 > [!TIP]

examples/map-server/README.md

@@ -1,5 +1,7 @@
 # Example: Interactive Map
 
+![Screenshot](screenshot.png)
+
 Interactive 3D globe viewer using CesiumJS with OpenStreetMap tiles. Demonstrates geocoding integration and full MCP App capabilities.
 
 ## Features

examples/shadertoy-server/README.md

@@ -50,7 +50,10 @@ _Tool input:_
 
 ```json
 {
-  "fragmentShader": "void mainImage(out vec4 fragColor, in vec2 fragCoord) {\n    vec2 uv = fragCoord / iResolution.xy;\n    fragColor = vec4(uv, 0.5 + 0.5*sin(iTime), 1.0);\n}"
+  "fragmentShader": "void mainImage(out vec4 fragColor, in vec2 fragCoord) {
+    vec2 uv = fragCoord / iResolution.xy;
+    fragColor = vec4(uv, 0.5 + 0.5*sin(iTime), 1.0);
+}"
 }
 ```
 
@@ -79,7 +82,22 @@ _Tool input:_
 
 ```json
 {
-  "fragmentShader": "void mainImage(out vec4 fragColor, in vec2 fragCoord) {\n    vec2 uv = (fragCoord - 0.5 * iResolution.xy) / iResolution.y;\n    float segments = 6.0;\n    float zoom = 1.0 + 0.3 * sin(iTime * 0.2);\n    float angle = atan(uv.y, uv.x) + iTime * 0.3;\n    float r = length(uv) * zoom;\n    angle = mod(angle, 6.28 / segments);\n    angle = abs(angle - 3.14 / segments);\n    vec2 p = vec2(cos(angle), sin(angle)) * r;\n    p += iTime * 0.1;\n    float v = sin(p.x * 10.0) * sin(p.y * 10.0);\n    v += sin(length(p) * 15.0 - iTime * 2.0);\n    v += sin(p.x * 5.0 + p.y * 7.0 + iTime);\n    vec3 col = 0.5 + 0.5 * cos(v * 2.0 + vec3(0.0, 2.0, 4.0) + iTime);\n    fragColor = vec4(col, 1.0);\n}"
+  "fragmentShader": "void mainImage(out vec4 fragColor, in vec2 fragCoord) {
+    vec2 uv = (fragCoord - 0.5 * iResolution.xy) / iResolution.y;
+    float segments = 6.0;
+    float zoom = 1.0 + 0.3 * sin(iTime * 0.2);
+    float angle = atan(uv.y, uv.x) + iTime * 0.3;
+    float r = length(uv) * zoom;
+    angle = mod(angle, 6.28 / segments);
+    angle = abs(angle - 3.14 / segments);
+    vec2 p = vec2(cos(angle), sin(angle)) * r;
+    p += iTime * 0.1;
+    float v = sin(p.x * 10.0) * sin(p.y * 10.0);
+    v += sin(length(p) * 15.0 - iTime * 2.0);
+    v += sin(p.x * 5.0 + p.y * 7.0 + iTime);
+    vec3 col = 0.5 + 0.5 * cos(v * 2.0 + vec3(0.0, 2.0, 4.0) + iTime);
+    fragColor = vec4(col, 1.0);
+}"
 }
 ```
 
@@ -108,7 +126,22 @@ _Tool input:_
 
 ```json
 {
-  "fragmentShader": "void mainImage(out vec4 fragColor, in vec2 fragCoord) {\n    vec2 uv = (fragCoord - 0.5 * iResolution.xy) / iResolution.y * 2.5;\n    vec2 mouse = (iMouse.xy / iResolution.xy - 0.5) * 2.0;\n    vec2 c = mouse;\n    vec2 z = uv;\n    float iter = 0.0;\n    for (int i = 0; i < 100; i++) {\n        z = vec2(z.x * z.x - z.y * z.y, 2.0 * z.x * z.y) + c;\n        if (dot(z, z) > 4.0) break;\n        iter++;\n    }\n    float t = iter / 100.0;\n    vec3 col = 0.5 + 0.5 * cos(3.0 + t * 6.28 * 2.0 + vec3(0.0, 0.6, 1.0));\n    if (iter == 100.0) col = vec3(0.0);\n    fragColor = vec4(col, 1.0);\n}"
+  "fragmentShader": "void mainImage(out vec4 fragColor, in vec2 fragCoord) {
+    vec2 uv = (fragCoord - 0.5 * iResolution.xy) / iResolution.y * 2.5;
+    vec2 mouse = (iMouse.xy / iResolution.xy - 0.5) * 2.0;
+    vec2 c = mouse;
+    vec2 z = uv;
+    float iter = 0.0;
+    for (int i = 0; i < 100; i++) {
+        z = vec2(z.x * z.x - z.y * z.y, 2.0 * z.x * z.y) + c;
+        if (dot(z, z) > 4.0) break;
+        iter++;
+    }
+    float t = iter / 100.0;
+    vec3 col = 0.5 + 0.5 * cos(3.0 + t * 6.28 * 2.0 + vec3(0.0, 0.6, 1.0));
+    if (iter == 100.0) col = vec3(0.0);
+    fragColor = vec4(col, 1.0);
+}"
 }
 ```
 

examples/sheet-music-server/README.md

@@ -38,7 +38,12 @@ When calling the `play-sheet-music` tool, provide ABC notation:
 
 ```json
 {
-  "abcNotation": "X:1\nT:C Major Scale\nM:4/4\nL:1/4\nK:C\nC D E F | G A B c |"
+  "abcNotation": "X:1
+T:C Major Scale
+M:4/4
+L:1/4
+K:C
+C D E F | G A B c |"
 }
 ```