chore: import upstream snapshot with attribution

tools/ui/vitest-setup-client.ts

@@ -0,0 +1,80 @@
+/// <reference types="@vitest/browser/matchers" />
+/// <reference types="@vitest/browser/providers/playwright" />
+
+import { beforeEach, vi } from 'vitest';
+
+// Mock fetch for API calls during client tests.
+// In test environment there is no backend server, so we intercept
+// the specific endpoints the app uses and return valid mock data.
+beforeEach(() => {
+	const originalFetch = globalThis.fetch;
+
+	vi.spyOn(globalThis, 'fetch').mockImplementation(
+		async (input: RequestInfo | URL, init?: RequestInit) => {
+			const url = typeof input === 'string' ? input : input instanceof URL ? input.href : input.url;
+
+			// Mock server props endpoint
+			if (url.includes('/server')) {
+				return new Response(
+					JSON.stringify({
+						mode: 'router',
+						version: 'test',
+						git_commit: 'test',
+						git_branch: 'test'
+					}),
+					{ status: 200, headers: { 'Content-Type': 'application/json' } }
+				);
+			}
+
+			// Mock models list endpoint
+			if (/\/v1\/models|\/models\b/.test(url)) {
+				return new Response(
+					JSON.stringify({
+						object: 'list',
+						data: [
+							{
+								id: 'test-model.gguf',
+								object: 'model',
+								owned_by: 'llamacpp',
+								created: 0,
+								in_cache: false,
+								path: 'models/test-model.gguf',
+								status: { value: 'unloaded' },
+								meta: {}
+							}
+						],
+						models: [
+							{
+								model: 'test-model.gguf',
+								name: 'Test Model',
+								details: {}
+							}
+						]
+					}),
+					{ status: 200, headers: { 'Content-Type': 'application/json' } }
+				);
+			}
+
+			// Mock /props endpoint (used for modalities)
+			if (url.includes('/props')) {
+				return new Response(
+					JSON.stringify({
+						default_generation_settings: { n_ctx: 2048 }
+					}),
+					{ status: 200, headers: { 'Content-Type': 'application/json' } }
+				);
+			}
+
+			// Mock /tools endpoint (used for built-in tools list)
+			if (url.includes('/tools')) {
+				return new Response(JSON.stringify([]), {
+					status: 200,
+					headers: { 'Content-Type': 'application/json' }
+				});
+			}
+
+			// Default: use real fetch
+			return originalFetch(input, init);
+		}
+	);
+});