fix: lint

Fixed JSON syntax for mcpServers configuration.

.changeset/gentle-pots-kneel.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/mcp': patch
+---
+
+fix: add icons to `server.json`

.changeset/moody-terms-beg.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/mcp': patch
+---
+
+fix: add `preferred-frame-size` to UI resource

.github/workflows/check.yml

@@ -18,7 +18,7 @@ jobs:
       - name: Setup pnpm
         uses: pnpm/action-setup@v4
         with:
-          version: 10.18.3
+          version: 10.19.0
 
       - name: Setup Node.js
         uses: actions/setup-node@v6

.github/workflows/lint.yml

@@ -18,7 +18,7 @@ jobs:
       - name: Setup pnpm
         uses: pnpm/action-setup@v4
         with:
-          version: 10.18.3
+          version: 10.19.0
 
       - name: Setup Node.js
         uses: actions/setup-node@v6

.github/workflows/publish-mcp.yml

@@ -5,6 +5,7 @@ on:
     secrets:
       MCP_KEY:
         required: true
+  workflow_dispatch:
 
 jobs:
   publish-mcp:
@@ -19,7 +20,7 @@ jobs:
         env:
           MCP_KEY: ${{ secrets.MCP_KEY }}
         run: |
-          NAME=mcp-publisher_1.3.3_$(uname -s | tr '[:upper:]' '[:lower:]')_$(uname -m | sed 's/x86_64/amd64/;s/aarch64/arm64/').tar.gz
+          NAME=mcp-publisher_$(uname -s | tr '[:upper:]' '[:lower:]')_$(uname -m | sed 's/x86_64/amd64/;s/aarch64/arm64/').tar.gz
           # Download MCP Publisher pinned to v1.3.3 using latest https for security and save it to a file named mcp-publisher.tar.gz
           curl --proto '=https' --proto-redir '=https' --tlsv1.2 -fL "https://github.com/modelcontextprotocol/registry/releases/download/v1.3.3/$NAME" -O
 

.github/workflows/test.yml

@@ -18,7 +18,7 @@ jobs:
       - name: Setup pnpm
         uses: pnpm/action-setup@v4
         with:
-          version: 10.18.3
+          version: 10.19.0
 
       - name: Setup Node.js
         uses: actions/setup-node@v6

apps/mcp-remote/package.json

@@ -59,12 +59,13 @@
 		"typescript": "^5.0.0",
 		"vite": "^7.0.4",
 		"vite-plugin-devtools-json": "^1.0.0",
-		"vitest": "^3.2.3"
+		"vitest": "^4.0.0"
 	},
 	"dependencies": {
 		"@sveltejs/mcp-schema": "workspace:^",
 		"@sveltejs/mcp-server": "workspace:^",
-		"@tmcp/transport-http": "^0.6.3",
-		"tmcp": "^1.15.0"
+		"@tmcp/transport-http": "^0.7.1",
+		"@vercel/analytics": "^1.5.0",
+		"tmcp": "^1.15.3"
 	}
 }

apps/mcp-remote/src/hooks.server.ts

@@ -1,8 +1,13 @@
+import { dev } from '$app/environment';
 import { http_transport } from '$lib/mcp/index.js';
 import { db } from '$lib/server/db/index.js';
 import { redirect } from '@sveltejs/kit';
+import { track } from '@vercel/analytics/server';
 
 export async function handle({ event, resolve }) {
+	if (event.request.method === 'POST') {
+		console.log(await event.request.clone().text());
+	}
 	if (event.request.method === 'GET') {
 		const accept = event.request.headers.get('accept');
 		if (accept) {
@@ -16,6 +21,12 @@ export async function handle({ event, resolve }) {
 	}
 	const mcp_response = await http_transport.respond(event.request, {
 		db,
+		// only add analytics in production
+		track: dev
+			? undefined
+			: async (session_id, event, slug) => {
+					await track(event, { session_id, ...(slug ? { slug } : {}) });
+				},
 	});
 	// we are deploying on vercel the SSE connection will timeout after 5 minutes...for
 	// the moment we are not sending back any notifications (logs, or list changed notifications)
@@ -25,11 +36,14 @@ export async function handle({ event, resolve }) {
 	// 200 or the MCP client will complain)
 	if (mcp_response && event.request.method === 'GET') {
 		try {
-			await mcp_response.body?.cancel();
-		} catch {
-			// ignore
+			return mcp_response;
+		} finally {
+			try {
+				await mcp_response.body?.cancel();
+			} catch {
+				// ignore
+			}
 		}
-		return new Response('', { status: 200 });
 	}
 	return mcp_response ?? resolve(event);
 }

apps/mcp-remote/src/lib/mcp/index.ts

@@ -3,4 +3,5 @@ import { HttpTransport } from '@tmcp/transport-http';
 
 export const http_transport = new HttpTransport(server, {
 	cors: true,
+	path: '/mcp',
 });

apps/mcp-remote/src/lib/server/db/index.ts

@@ -1,8 +1,6 @@
 import { createClient } from '@libsql/client';
 import { drizzle } from 'drizzle-orm/libsql';
 import * as schema from './schema.js';
-// let's disable it for the moment...i can't figure out a way to make it wotk with eslint
-// eslint-disable-next-line import/extensions
 import { DATABASE_TOKEN, DATABASE_URL } from '$env/static/private';
 if (!DATABASE_URL) throw new Error('DATABASE_URL is not set');
 if (!DATABASE_TOKEN) throw new Error('DATABASE_TOKEN is not set');

documentation/docs/20-setup/30-remote-setup.md

@@ -96,6 +96,27 @@ It will open a file with your MCP servers where you can add the following config
 }
 ```
 
+## GitHub Coding Agent
+
+- Open your repository in GitHub
+- Go to Settings
+- Open Copilot > Coding agent
+- Edit the MCP configuration
+
+```json
+{
+	"mcpServers": {
+		"svelte": {
+			"type": "http",
+			"url": "https://mcp.svelte.dev/mcp",
+			"tools": ["*"]
+		}
+	}
+}
+```
+
+- Click _Save MCP configuration_
+
 ## Other clients
 
 If we didn't include the MCP client you are using, refer to their documentation for `remote` servers and use `https://mcp.svelte.dev/mcp` as the URL.

eslint.config.js

@@ -48,13 +48,17 @@ export default /** @type {import("eslint").Linter.Config} */ ([
 			'import/no-unresolved': 'off', // this doesn't work well with typescript path mapping
 			'import/extensions': [
 				'error',
-				'ignorePackages',
 				{
-					js: 'always',
-					mjs: 'always',
-					cjs: 'always',
-					ts: 'always',
-					svelte: 'always',
+					ignorePackages: true,
+					pattern: {
+						js: 'always',
+						mjs: 'always',
+						cjs: 'always',
+						ts: 'always',
+						svelte: 'always',
+						svg: 'always',
+						json: 'always',
+					},
 				},
 			],
 		},

package.json

@@ -3,7 +3,7 @@
 	"version": "0.0.1",
 	"description": "The official Svelte MCP server implementation",
 	"type": "module",
-	"packageManager": "pnpm@10.18.3",
+	"packageManager": "pnpm@10.19.0",
 	"scripts": {
 		"build": "pnpm -r run build",
 		"dev": "pnpm --filter @sveltejs/mcp-remote run dev",
@@ -46,7 +46,7 @@
 		"publint": "^0.3.13",
 		"typescript": "^5.0.0",
 		"typescript-eslint": "^8.44.1",
-		"vitest": "^3.2.3"
+		"vitest": "^4.0.0"
 	},
 	"pnpm": {
 		"onlyBuiltDependencies": [

packages/mcp-server/package.json

@@ -20,6 +20,7 @@
 		"drizzle-orm": "^0.44.0"
 	},
 	"dependencies": {
+		"@mcp-ui/server": "^5.12.0",
 		"@sveltejs/mcp-schema": "workspace:^",
 		"@tmcp/adapter-valibot": "^0.1.4",
 		"@typescript-eslint/parser": "^8.44.0",
@@ -27,11 +28,11 @@
 		"eslint-plugin-svelte": "^3.12.3",
 		"svelte": "^5.39.2",
 		"svelte-eslint-parser": "^1.3.2",
-		"tmcp": "^1.15.0",
+		"tmcp": "^1.15.3",
 		"ts-blank-space": "^0.6.2",
 		"typescript-eslint": "^8.44.0",
 		"valibot": "^1.1.0",
-		"vitest": "^3.2.4",
+		"vitest": "^4.0.0",
 		"zimmerframe": "^1.1.4"
 	},
 	"devDependencies": {

packages/mcp-server/src/mcp/handlers/prompts/svelte-task.ts

@@ -68,6 +68,9 @@ export function setup_svelte_task(server: SvelteMcp) {
 			icons,
 		},
 		async ({ task }) => {
+			if (server.ctx.sessionId && server.ctx.custom?.track) {
+				await server.ctx.custom?.track?.(server.ctx.sessionId, 'svelte-task');
+			}
 			const available_docs = await format_sections_list();
 
 			return {

packages/mcp-server/src/mcp/handlers/resources/doc-section.ts

@@ -46,6 +46,13 @@ export async function list_sections(server: SvelteMcp) {
 			icons,
 		},
 		async (uri, { slug }) => {
+			if (server.ctx.sessionId && server.ctx.custom?.track) {
+				await server.ctx.custom?.track?.(
+					server.ctx.sessionId,
+					'svelte-doc-section',
+					Array.isArray(slug) ? slug.join(',') : slug,
+				);
+			}
 			const section = sections.find((section) => {
 				return slug === section.slug;
 			});

packages/mcp-server/src/mcp/handlers/tools/get-documentation.ts

@@ -21,6 +21,9 @@ export function get_documentation(server: SvelteMcp) {
 			icons,
 		},
 		async ({ section }) => {
+			if (server.ctx.sessionId && server.ctx.custom?.track) {
+				await server.ctx.custom?.track?.(server.ctx.sessionId, 'get-documentation');
+			}
 			let sections: string[];
 
 			if (Array.isArray(section)) {

packages/mcp-server/src/mcp/handlers/tools/list-sections.ts

@@ -12,6 +12,9 @@ export function list_sections(server: SvelteMcp) {
 			icons,
 		},
 		async () => {
+			if (server.ctx.sessionId && server.ctx.custom?.track) {
+				await server.ctx.custom?.track?.(server.ctx.sessionId, 'list-sections');
+			}
 			const formatted_sections = await format_sections_list();
 
 			return {

packages/mcp-server/src/mcp/handlers/tools/playground-link.ts

@@ -1,6 +1,7 @@
 import type { SvelteMcp } from '../../index.js';
 import * as v from 'valibot';
 import { icons } from '../../icons/index.js';
+import { createUIResource } from '@mcp-ui/server';
 
 async function compress_and_encode_text(input: string) {
 	const reader = new Blob([input]).stream().pipeThrough(new CompressionStream('gzip')).getReader();
@@ -58,6 +59,9 @@ export function playground_link(server: SvelteMcp) {
 			icons,
 		},
 		async ({ files, name, tailwind }) => {
+			if (server.ctx.sessionId && server.ctx.custom?.track) {
+				await server.ctx.custom?.track?.(server.ctx.sessionId, 'playground-link');
+			}
 			const playground_base = new URL('https://svelte.dev/playground');
 			const playground_files: File[] = [];
 
@@ -75,6 +79,9 @@ export function playground_link(server: SvelteMcp) {
 			}
 
 			if (!has_app_svelte) {
+				if (server.ctx.sessionId && server.ctx.custom?.track) {
+					await server.ctx.custom?.track?.(server.ctx.sessionId, 'playground-link-no-app-svelte');
+				}
 				return {
 					isError: true,
 					content: [
@@ -100,12 +107,26 @@ export function playground_link(server: SvelteMcp) {
 				url: playground_base.toString(),
 			};
 
+			// use the embed path to have a cleaner UI for mcp-ui
+			playground_base.pathname = '/playground/embed';
+
 			return {
 				content: [
 					{
 						type: 'text',
 						text: JSON.stringify(content),
 					},
+					createUIResource({
+						uri: 'ui://svelte/playground-link',
+						content: {
+							type: 'externalUrl',
+							iframeUrl: playground_base.toString(),
+						},
+						uiMetadata: {
+							'preferred-frame-size': ['100%', '1200px'],
+						},
+						encoding: 'text',
+					}),
 				],
 				structuredContent: content,
 			};

packages/mcp-server/src/mcp/handlers/tools/svelte-autofixer.test.ts

@@ -0,0 +1,94 @@
+import { beforeEach, describe, expect, it } from 'vitest';
+import { server } from '../../index.js';
+
+/**
+ * Small utility to create a JSON-RPC request without having to always specify as const
+ */
+function request<const T>(request: T) {
+	return request;
+}
+
+async function autofixer_tool_call(code: string, is_error = false, desired_svelte_version = 5) {
+	const result = await server.receive({
+		jsonrpc: '2.0',
+		id: 2,
+		method: 'tools/call',
+		params: {
+			name: 'svelte-autofixer',
+			arguments: {
+				code,
+				desired_svelte_version,
+				filename: 'App.svelte',
+			},
+		},
+	});
+
+	expect(result).toBeDefined();
+	expect(result.result).toBeDefined();
+	if (is_error) {
+		return result.result;
+	}
+	expect(result.result.structuredContent).toBeDefined();
+	return result.result.structuredContent;
+}
+
+describe('svelte-autofixer tool', () => {
+	beforeEach(async () => {
+		const initialize_request = request({
+			jsonrpc: '2.0',
+			id: 1,
+			method: 'initialize',
+			params: {
+				protocolVersion: '2025-06-18',
+				capabilities: {
+					roots: { listChanged: true },
+				},
+				clientInfo: {
+					name: 'test-client',
+					version: '1.0.0',
+				},
+			},
+		});
+
+		await server.receive(initialize_request, {
+			sessionId: 'svelte-autofixer-session',
+		});
+	});
+
+	it('should add suggestions for js parse errors', async () => {
+		const content = await autofixer_tool_call(`<script>
+			$state count = 0;
+		</script>`);
+		expect(content.issues.length).toBeGreaterThan(0);
+		expect(content.suggestions).toContain(
+			"The code can't be compiled because a Javascript parse error. In case you are using runes like this `$state variable_name = 3;` or `$derived variable_name = 3 * count` that's not how runes are used. You need to use them as function calls without importing them: `const variable_name = $state(3)` and `const variable_name = $derived(3 * count)`.",
+		);
+	});
+
+	it('should add suggestions for css invalid identifier', async () => {
+		const content = await autofixer_tool_call(`<script>
+				let my_color = $state('red');
+			</script>
+							
+			<style>
+				.my-class {
+					color: {my_color};
+				}
+			</style>`);
+
+		expect(content.issues.length).toBeGreaterThan(0);
+		expect(content.suggestions).toContain(
+			"The code can't be compiled because a valid CSS identifier is expected. This sometimes means you are trying to use a variable in CSS like this: `color: {my_color}` but Svelte doesn't support that. You can use inline CSS variables for that `<div style:--color={my_color}></div>` and then use the variable as usual in CSS with `color: var(--color)`.",
+		);
+	});
+
+	it('should error in case the passed in version is different from 4 or 5', async () => {
+		const content = await autofixer_tool_call(`whatever`, true, 3);
+
+		expect(content.content).toBeDefined();
+		expect(content.content[0]).toBeDefined();
+		expect(content.content[0].text).toContain(
+			'The desired_svelte_version MUST be either 4 or 5 but received "3"',
+		);
+	});
+});

packages/mcp-server/src/mcp/handlers/tools/svelte-autofixer.ts

@@ -46,12 +46,18 @@ export function svelte_autofixer(server: SvelteMcp) {
 			filename: filename_or_path,
 			desired_svelte_version: desired_svelte_version_unchecked,
 		}) => {
+			if (server.ctx.sessionId && server.ctx.custom?.track) {
+				await server.ctx.custom?.track?.(server.ctx.sessionId, 'svelte-autofixer');
+			}
 			// we validate manually because some clients don't support union in the input schema (looking at you cursor)
 			const parsed_version = v.safeParse(
 				v.union([v.literal(4), v.literal(5), v.literal('4'), v.literal('5')]),
 				desired_svelte_version_unchecked,
 			);
 			if (parsed_version.success === false) {
+				if (server.ctx.sessionId && server.ctx.custom?.track) {
+					await server.ctx.custom?.track?.(server.ctx.sessionId, 'svelte-autofixer-wrong-version');
+				}
 				return {
 					isError: true,
 					content: [
@@ -90,6 +96,10 @@ export function svelte_autofixer(server: SvelteMcp) {
 					content.suggestions.push(
 						"The code can't be compiled because a Javascript parse error. In case you are using runes like this `$state variable_name = 3;` or `$derived variable_name = 3 * count` that's not how runes are used. You need to use them as function calls without importing them: `const variable_name = $state(3)` and `const variable_name = $derived(3 * count)`.",
 					);
+				} else if (error.message.includes('css_expected_identifier')) {
+					content.suggestions.push(
+						"The code can't be compiled because a valid CSS identifier is expected. This sometimes means you are trying to use a variable in CSS like this: `color: {my_color}` but Svelte doesn't support that. You can use inline CSS variables for that `<div style:--color={my_color}></div>` and then use the variable as usual in CSS with `color: var(--color)`.",
+					);
 				}
 			}
 

packages/mcp-server/src/mcp/index.ts

@@ -24,7 +24,10 @@ export const server = new McpServer(
 		instructions:
 			'This is the official Svelte MCP server. It MUST be used whenever svelte development is involved. It can provide official documentation, code examples and correct your code. After you correct the component call this tool again to confirm all the issues are fixed.',
 	},
-).withContext<{ db: LibSQLDatabase<Schema> }>();
+).withContext<{
+	db: LibSQLDatabase<Schema>;
+	track?: (sessionId: string, event: string, slug?: string) => Promise<void>;
+}>();
 
 export type SvelteMcp = typeof server;
 

packages/mcp-stdio/CHANGELOG.md

@@ -1,5 +1,13 @@
 # @sveltejs/mcp
 
+## 0.1.9
+
+### Patch Changes
+
+- feat: return `mcp-ui` resource from `playground-link` ([#84](https://github.com/sveltejs/mcp/pull/84))
+
+- feat: suggest against js variables in css ([#78](https://github.com/sveltejs/mcp/pull/78))
+
 ## 0.1.8
 
 ### Patch Changes

packages/mcp-stdio/package.json

@@ -1,6 +1,6 @@
 {
 	"name": "@sveltejs/mcp",
-	"version": "0.1.8",
+	"version": "0.1.9",
 	"type": "module",
 	"license": "MIT",
 	"mcpName": "dev.svelte/mcp",
@@ -37,10 +37,10 @@
 		"publint": "^0.3.13",
 		"tsdown": "^0.15.0",
 		"typescript": "^5.8.3",
-		"vitest": "^3.1.3"
+		"vitest": "^4.0.0"
 	},
 	"dependencies": {
 		"eslint": "^9.36.0",
-		"tmcp": "^1.15.0"
+		"tmcp": "^1.15.3"
 	}
 }

packages/mcp-stdio/server.json

@@ -8,13 +8,23 @@
 		"subfolder": "packages/mcp-stdio",
 		"source": "github"
 	},
-	"version": "0.1.8",
+	"version": "0.1.9",
 	"websiteUrl": "https://svelte.dev/docs/mcp/overview",
+	"icons": [
+		{
+			"src": "https://mcp.svelte.dev/logo.svg",
+			"mimeType": "image/svg+xml"
+		},
+		{
+			"src": "https://mcp.svelte.dev/logo.png",
+			"mimeType": "image/png"
+		}
+	],
 	"packages": [
 		{
 			"registryType": "npm",
 			"identifier": "@sveltejs/mcp",
-			"version": "0.1.8",
+			"version": "0.1.9",
 			"runtimeHint": "npx",
 			"transport": {
 				"type": "stdio"