Add Playwright e2e tests for CLI argument handling

- Test that transport and serverUrl parameters are correctly passed via URL
- Verify SSE and streamable-http transport types are handled
- Test default STDIO behavior

Author: felixweinberger

client/e2e/cli-arguments.spec.ts

@@ -0,0 +1,61 @@
+import { test, expect } from "@playwright/test";
+
+// These tests verify that CLI arguments correctly set URL parameters
+// The CLI should parse config files and pass transport/serverUrl as URL params
+test.describe("CLI Arguments @cli", () => {
+  test("should pass transport parameter from command line", async ({
+    page,
+  }) => {
+    // Simulate: npx . --transport sse --server-url http://localhost:3000/sse
+    await page.goto("http://localhost:6274/?transport=sse&serverUrl=http://localhost:3000/sse");
+
+    // Wait for the Transport Type dropdown to be visible
+    const selectTrigger = page.getByLabel("Transport Type");
+    await expect(selectTrigger).toBeVisible();
+
+    // Verify transport dropdown shows SSE
+    await expect(selectTrigger).toContainText("SSE");
+
+    // Verify URL field is visible and populated
+    const urlInput = page.locator("#sse-url-input");
+    await expect(urlInput).toBeVisible();
+    await expect(urlInput).toHaveValue("http://localhost:3000/sse");
+  });
+
+  test("should pass transport parameter for streamable-http", async ({
+    page,
+  }) => {
+    // Simulate config with streamable-http transport
+    await page.goto("http://localhost:6274/?transport=streamable-http&serverUrl=http://localhost:3000/mcp");
+
+    // Wait for the Transport Type dropdown to be visible
+    const selectTrigger = page.getByLabel("Transport Type");
+    await expect(selectTrigger).toBeVisible();
+
+    // Verify transport dropdown shows Streamable HTTP
+    await expect(selectTrigger).toContainText("Streamable HTTP");
+
+    // Verify URL field is visible and populated
+    const urlInput = page.locator("#sse-url-input");
+    await expect(urlInput).toBeVisible();
+    await expect(urlInput).toHaveValue("http://localhost:3000/mcp");
+  });
+
+  test("should not pass transport parameter for stdio config", async ({
+    page,
+  }) => {
+    // Simulate stdio config (no transport param needed)
+    await page.goto("http://localhost:6274/");
+
+    // Wait for the Transport Type dropdown to be visible
+    const selectTrigger = page.getByLabel("Transport Type");
+    await expect(selectTrigger).toBeVisible();
+
+    // Verify transport dropdown defaults to STDIO
+    await expect(selectTrigger).toContainText("STDIO");
+
+    // Verify command/args fields are visible
+    await expect(page.locator("#command-input")).toBeVisible();
+    await expect(page.locator("#arguments-input")).toBeVisible();
+  });
+});