diff --git a/.changeset/thirty-ducks-buy.md b/.changeset/thirty-ducks-buy.md
new file mode 100644
index 00000000..db7f3b21
--- /dev/null
+++ b/.changeset/thirty-ducks-buy.md
@@ -0,0 +1,5 @@
+---
+'sv': patch
+---
+
+feat: `vitest` use client and server side testing for `kit`
diff --git a/packages/addons/vitest-addon/index.ts b/packages/addons/vitest-addon/index.ts
index 88059301..895224a7 100644
--- a/packages/addons/vitest-addon/index.ts
+++ b/packages/addons/vitest-addon/index.ts
@@ -1,12 +1,12 @@
 import { dedent, defineAddon, log } from '@sveltejs/cli-core';
-import { common, exports, imports, object } from '@sveltejs/cli-core/js';
+import { array, common, exports, functions, imports, object } from '@sveltejs/cli-core/js';
 import { parseJson, parseScript } from '@sveltejs/cli-core/parsers';
 
 export default defineAddon({
 	id: 'vitest',
 	homepage: 'https://vitest.dev',
 	options: {},
-	run: ({ sv, typescript }) => {
+	run: ({ sv, typescript, kit }) => {
 		const ext = typescript ? 'ts' : 'js';
 
 		sv.devDependency('vitest', '^2.0.4');
@@ -38,63 +38,143 @@ export default defineAddon({
 			`;
 		});
 
-		sv.file(`vite.config.${ext}`, (content) => {
-			const { ast, generateCode } = parseScript(content);
-
-			// find `defineConfig` import declaration for "vite"
-			const importDecls = ast.body.filter((n) => n.type === 'ImportDeclaration');
-			const defineConfigImportDecl = importDecls.find(
-				(importDecl) =>
-					(importDecl.source.value === 'vite' || importDecl.source.value === 'vitest/config') &&
-					importDecl.importKind === 'value' &&
-					importDecl.specifiers?.some(
-						(specifier) =>
-							specifier.type === 'ImportSpecifier' && specifier.imported.name === 'defineConfig'
-					)
-			);
-
-			// we'll need to replace the "vite" import for a "vitest/config" import.
-			// if `defineConfig` is the only specifier in that "vite" import, remove the entire import declaration
-			if (defineConfigImportDecl?.specifiers?.length === 1) {
-				const idxToRemove = ast.body.indexOf(defineConfigImportDecl);
-				ast.body.splice(idxToRemove, 1);
-			} else {
-				// otherwise, just remove the `defineConfig` specifier
-				const idxToRemove = defineConfigImportDecl?.specifiers?.findIndex(
-					(s) => s.type === 'ImportSpecifier' && s.imported.name === 'defineConfig'
-				);
-				if (idxToRemove) defineConfigImportDecl?.specifiers?.splice(idxToRemove, 1);
-			}
+		if (kit) {
+			sv.devDependency('@testing-library/svelte', '^5.2.4');
+			sv.devDependency('@testing-library/jest-dom', '^6.6.3');
+			sv.devDependency('jsdom', '^25.0.1');
+
+			sv.file(`${kit.routesDirectory}/page.svelte.test.${ext}`, (content) => {
+				if (content) return content;
 
-			const config = common.expressionFromString('defineConfig({})');
-			const defaultExport = exports.defaultExport(ast, config);
+				return dedent`
+					import { describe,test, expect } from "vitest";
+					import { render, screen } from '@testing-library/svelte';
+					import Page from  './+page.svelte';
 
-			const test = object.create({
-				include: common.expressionFromString("['src/**/*.{test,spec}.{js,ts}']")
+					describe('/+page.svelte',()=>{
+						test('should render h1',()=>{
+							render(Page);
+							expect(screen.getByRole('heading',{level:1})).toBeInTheDocument();
+						})
+					})
+				`;
 			});
 
-			// uses the `defineConfig` helper
-			if (
-				defaultExport.value.type === 'CallExpression' &&
-				defaultExport.value.arguments[0]?.type === 'ObjectExpression'
-			) {
-				// if the previous `defineConfig` was aliased, reuse the alias for the "vitest/config" import
-				const importSpecifier = defineConfigImportDecl?.specifiers?.find(
-					(sp) => sp.type === 'ImportSpecifier' && sp.imported.name === 'defineConfig'
+			sv.file('vitest-setup-client.ts', (content) => {
+				if (content) return content;
+
+				return dedent`
+					import '@testing-library/jest-dom/vitest'
+
+					// add global mocks here, i.e. for sveltekit '$app/stores'
+				`;
+			});
+
+			sv.file('vitest.workspace.ts', (content) => {
+				const { ast, generateCode } = parseScript(content);
+
+				imports.addNamed(ast, 'vitest/config', { defineWorkspace: 'defineWorkspace' });
+				imports.addNamed(ast, '@testing-library/svelte/vite', { svelteTesting: 'svelteTesting' });
+
+				const clientObjectExpression = object.create({
+					extends: common.createLiteral(`./vite.config.${ext}`),
+					plugins: common.expressionFromString(
+						'[svelteTesting({resolveBrowser: true,autoCleanup: true})]'
+					),
+					test: object.create({
+						name: common.createLiteral('client'),
+						environment: common.createLiteral('jsdom'),
+						clearMocks: common.expressionFromString('true'),
+						include: common.expressionFromString('["src/**/*.svelte.{test,spec}.{js,ts}"]'),
+						exclude: common.expressionFromString('["src/lib/server/**"]'),
+						setupFiles: common.expressionFromString('["./vitest-setup-client.ts"]')
+					})
+				});
+				const serverObjectExpression = object.create({
+					extends: common.createLiteral(`./vite.config.${ext}`),
+					test: object.create({
+						name: common.createLiteral('server'),
+						environment: common.createLiteral('node'),
+						include: common.expressionFromString('["src/**/*.{test,spec}.{js,ts}"]'),
+						exclude: common.expressionFromString('["src/**/*.svelte.{test,spec}.{js,ts}"]')
+					})
+				});
+
+				const defineWorkspaceFallback = functions.call('defineWorkspace', []);
+				const { value: defineWorkspaceCall } = exports.defaultExport(ast, defineWorkspaceFallback);
+				if (defineWorkspaceCall.type !== 'CallExpression') {
+					log.warn('Unexpected vite config for vitest add-on. Could not update.');
+				}
+
+				const workspaceArray = functions.argumentByIndex(
+					defineWorkspaceCall,
+					0,
+					array.createEmpty()
 				);
-				const defineConfigAlias = (importSpecifier?.local?.name ?? 'defineConfig') as string;
-				imports.addNamed(ast, 'vitest/config', { defineConfig: defineConfigAlias });
-
-				object.properties(defaultExport.value.arguments[0], { test });
-			} else if (defaultExport.value.type === 'ObjectExpression') {
-				// if the config is just an object expression, just add the property
-				object.properties(defaultExport.value, { test });
-			} else {
-				// unexpected config shape
-				log.warn('Unexpected vite config for vitest add-on. Could not update.');
-			}
+				array.push(workspaceArray, clientObjectExpression);
+				array.push(workspaceArray, serverObjectExpression);
 
-			return generateCode();
-		});
+				return generateCode();
+			});
+		} else {
+			sv.file(`vite.config.${ext}`, (content) => {
+				const { ast, generateCode } = parseScript(content);
+
+				// find `defineConfig` import declaration for "vite"
+				const importDecls = ast.body.filter((n) => n.type === 'ImportDeclaration');
+				const defineConfigImportDecl = importDecls.find(
+					(importDecl) =>
+						(importDecl.source.value === 'vite' || importDecl.source.value === 'vitest/config') &&
+						importDecl.importKind === 'value' &&
+						importDecl.specifiers?.some(
+							(specifier) =>
+								specifier.type === 'ImportSpecifier' && specifier.imported.name === 'defineConfig'
+						)
+				);
+
+				// we'll need to replace the "vite" import for a "vitest/config" import.
+				// if `defineConfig` is the only specifier in that "vite" import, remove the entire import declaration
+				if (defineConfigImportDecl?.specifiers?.length === 1) {
+					const idxToRemove = ast.body.indexOf(defineConfigImportDecl);
+					ast.body.splice(idxToRemove, 1);
+				} else {
+					// otherwise, just remove the `defineConfig` specifier
+					const idxToRemove = defineConfigImportDecl?.specifiers?.findIndex(
+						(s) => s.type === 'ImportSpecifier' && s.imported.name === 'defineConfig'
+					);
+					if (idxToRemove) defineConfigImportDecl?.specifiers?.splice(idxToRemove, 1);
+				}
+
+				const config = common.expressionFromString('defineConfig({})');
+				const defaultExport = exports.defaultExport(ast, config);
+
+				const test = object.create({
+					include: common.expressionFromString("['src/**/*.{test,spec}.{js,ts}']")
+				});
+
+				// uses the `defineConfig` helper
+				if (
+					defaultExport.value.type === 'CallExpression' &&
+					defaultExport.value.arguments[0]?.type === 'ObjectExpression'
+				) {
+					// if the previous `defineConfig` was aliased, reuse the alias for the "vitest/config" import
+					const importSpecifier = defineConfigImportDecl?.specifiers?.find(
+						(sp) => sp.type === 'ImportSpecifier' && sp.imported.name === 'defineConfig'
+					);
+					const defineConfigAlias = (importSpecifier?.local?.name ?? 'defineConfig') as string;
+					imports.addNamed(ast, 'vitest/config', { defineConfig: defineConfigAlias });
+
+					object.properties(defaultExport.value.arguments[0], { test });
+				} else if (defaultExport.value.type === 'ObjectExpression') {
+					// if the config is just an object expression, just add the property
+					object.properties(defaultExport.value, { test });
+				} else {
+					// unexpected config shape
+					log.warn('Unexpected vite config for vitest add-on. Could not update.');
+				}
+
+				return generateCode();
+			});
+		}
 	}
 });