fix(mcp): require the panel key for panel requests

panel_request now requires a key that each MCP server generates and places
in its panel page, which keeps the tool from clients that list it to the
model without loading the panel. The key is not access control: any MCP
client can read the panel page. Routes the panel never loads (provider
settings, credential and model endpoints, the MCP endpoint and development
server internals) are refused to every caller, regardless of letter case or
encoding.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

src/tools/localServer.test.mjs

@@ -131,3 +131,43 @@ test('a failed tool call is logged with its reason', async () => {
     '   tools/call show_in_gods_eye_view failed: bad area',
   ]);
 });
+
+test("only the key in the server's own panel page opens panel requests", async () => {
+  const requested = [];
+  const server = createLocalMcpServer({
+    apiBase: 'http://127.0.0.1:5000',
+    fetchImpl: async (url) => {
+      requested.push(new URL(url).pathname);
+      return new Response('ok');
+    },
+  });
+  const call = (id, args) =>
+    server.handle({
+      jsonrpc: '2.0',
+      id,
+      method: 'tools/call',
+      params: { name: 'panel_request', arguments: args },
+    });
+  const page = await server.handle({
+    jsonrpc: '2.0',
+    id: 1,
+    method: 'resources/read',
+    params: { uri: 'ui://gods-eye-view/globe' },
+  });
+  const [, key] = page.result.contents[0].text.match(/"panelKey":"([^"]+)"/);
+  assert.ok(key.length >= 40);
+  const refused = await call(2, { path: '/panel/index.html' });
+  assert.equal(refused.result.isError, true);
+  const opened = await call(3, { key, path: '/panel/index.html' });
+  assert.equal(opened.result.isError, false);
+  assert.deepEqual(requested, ['/panel/index.html']);
+  // Every server makes its own key.
+  const other = createLocalMcpServer({ apiBase: 'http://127.0.0.1:5000' });
+  const otherPage = await other.handle({
+    jsonrpc: '2.0',
+    id: 4,
+    method: 'resources/read',
+    params: { uri: 'ui://gods-eye-view/globe' },
+  });
+  assert.doesNotMatch(otherPage.result.contents[0].text, new RegExp(key));
+});