Load the God's Eye View panel through the MCP server

Hosts serve panels from their own sites and may refuse other addresses;
Codex refuses any address on the user's machine. The panel now never
requests the app's server: it loads the app's panel build and data
through panel_request, a tool only the panel may call, which requests
the path from the app's server. One path in every host; only map
providers load directly.

npm run build:panel writes the panel build to dist/panel, served at
/panel/: one app script, one stylesheet, Cesium's script, and Cesium's
workers as one script Cesium runs from memory. Tools may now be marked
app-only. The panel CORS rules are gone.

src/tools/queries/panelRequest.test.mjs

@@ -0,0 +1,109 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import { composeCatalog, coreTools } from '../index.js';
+import { PANEL_PART_BYTES } from './panelRequest.js';
+
+const fromBase64 = (text) => Buffer.from(text, 'base64');
+const gunzip = async (bytes) =>
+  new Uint8Array(
+    await new Response(
+      new Blob([bytes]).stream().pipeThrough(new DecompressionStream('gzip')),
+    ).arrayBuffer(),
+  );
+
+function catalogWith(handler) {
+  const requests = [];
+  const fetchImpl = async (path, init) => {
+    requests.push({ path, ...init });
+    return handler(path, init);
+  };
+  return {
+    requests,
+    catalog: composeCatalog({
+      tools: coreTools,
+      services: {
+        app: { baseUrl: 'http://localhost:4173/', fetch: fetchImpl },
+      },
+    }),
+  };
+}
+
+test('panel_request is for the panel only', () => {
+  const { catalog } = catalogWith(() => new Response('x'));
+  assert.deepEqual(catalog.get('panel_request').ui, { visibility: ['app'] });
+});
+
+test('a small response returns whole, compressed when that helps', async () => {
+  const text = 'body { color: red; }\n'.repeat(200);
+  const { catalog, requests } = catalogWith(
+    () =>
+      new Response(text, {
+        status: 200,
+        headers: { 'content-type': 'text/css', 'set-cookie': 'a=b' },
+      }),
+  );
+  const { data } = await catalog.call('panel_request', {
+    path: '/panel/assets/style.css',
+    headers: { Accept: 'text/css', Cookie: 'secret', 'X-Other': '1' },
+  });
+  assert.deepEqual(requests[0].headers, { Accept: 'text/css' });
+  assert.equal(data.status, 200);
+  assert.equal(data.encoding, 'gzip');
+  assert.equal(data.nextOffset, undefined);
+  assert.equal(data.headers['content-type'], 'text/css');
+  assert.equal(data.headers['set-cookie'], undefined);
+  const body = await gunzip(fromBase64(data.body));
+  assert.equal(new TextDecoder().decode(body), text);
+});
+
+test('a large response comes in parts that join to the original', async () => {
+  const bytes = new Uint8Array(PANEL_PART_BYTES * 2 + 10);
+  for (let index = 0; index < bytes.length; index++)
+    bytes[index] = (index * 7919) % 251;
+  const { catalog } = catalogWith(
+    () => new Response(bytes, { headers: { 'content-type': 'image/png' } }),
+  );
+  let { data } = await catalog.call('panel_request', { path: '/a.png' });
+  assert.equal(data.encoding, 'identity');
+  assert.equal(data.totalBytes, bytes.length);
+  const parts = [fromBase64(data.body)];
+  while (data.nextOffset !== undefined) {
+    ({ data } = await catalog.call('panel_request', {
+      id: data.id,
+      offset: data.nextOffset,
+    }));
+    parts.push(fromBase64(data.body));
+  }
+  assert.equal(parts.length, 3);
+  assert.deepEqual(new Uint8Array(Buffer.concat(parts)), bytes);
+});
+
+test('a request body and method pass through; settings and other sites do not', async () => {
+  const { catalog, requests } = catalogWith(
+    () => new Response('{}', { status: 201 }),
+  );
+  const { data } = await catalog.call('panel_request', {
+    path: '/api/openai/hud-summary',
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: Buffer.from('{"a":1}').toString('base64'),
+  });
+  assert.equal(data.status, 201);
+  assert.equal(new TextDecoder().decode(requests[0].body), '{"a":1}');
+  for (const path of [
+    '/api/setup/status',
+    '/api/setup',
+    '//evil.example/x',
+    'http://evil.example/',
+  ])
+    await assert.rejects(
+      catalog.call('panel_request', { path }),
+      (error) => error.code === 'invalid_arguments',
+      path,
+    );
+  await assert.rejects(
+    catalog.call('panel_request', { id: 'unknown' }),
+    (error) => error.code === 'invalid_arguments',
+  );
+  assert.equal(requests.length, 1);
+});