fix(search): geocode through the server, not the browser

- Google's Geocoding web service refuses referrer-restricted keys, so the
  browser call forced GOOGLE_MAPS_API_KEY to ship unrestricted
- add /api/google/geocode and /api/google/reverse-geocode, using the server
  key like Places and Street View already do
- the browser key now needs the Map Tiles API only

src/googleGeocodeProxy.test.mjs

@@ -0,0 +1,167 @@
+import assert from 'node:assert/strict';
+import test from 'node:test';
+import {
+  googlePlacesContextProxy,
+  validateGeocodeAddress,
+  geocodeBounds,
+} from '../vite.config.js';
+
+const UPSTREAM = 'https://geocode.test/json';
+
+function installRoutes({ apiKey = 'server-secret', fetchImpl } = {}) {
+  const routes = new Map();
+  googlePlacesContextProxy({
+    resolveApiKey: () => apiKey,
+    fetchImpl,
+    endpoints: { geocode: UPSTREAM },
+  }).configureServer({
+    middlewares: { use: (name, handler) => routes.set(name, handler) },
+  });
+  return routes;
+}
+
+function invokeRoute(handler, { method = 'GET', url = '/' } = {}) {
+  return new Promise((resolve, reject) => {
+    const headers = new Map();
+    const res = {
+      statusCode: 200,
+      setHeader(name, value) {
+        headers.set(String(name).toLowerCase(), String(value));
+      },
+      end(body = '') {
+        resolve({
+          statusCode: this.statusCode,
+          headers: Object.fromEntries(headers),
+          body: body ? JSON.parse(String(body)) : null,
+        });
+      },
+    };
+    Promise.resolve(
+      handler(
+        { method, url, headers: {}, socket: { remoteAddress: '127.0.0.1' } },
+        res,
+      ),
+    ).catch(reject);
+  });
+}
+
+test('geocoder query and viewport bias are validated before Google is paid', () => {
+  assert.deepEqual(validateGeocodeAddress(new URLSearchParams()), {
+    ok: false,
+    error: 'address is required',
+  });
+  assert.deepEqual(validateGeocodeAddress(new URLSearchParams({ address: '  ' })), {
+    ok: false,
+    error: 'address is required',
+  });
+  assert.deepEqual(
+    validateGeocodeAddress(new URLSearchParams({ address: 'x'.repeat(201) })),
+    { ok: false, error: 'address is too long' },
+  );
+  assert.deepEqual(
+    validateGeocodeAddress(new URLSearchParams({ address: ' Austin ' })),
+    { ok: true, address: 'Austin' },
+  );
+
+  // A bias only ranks results, so an unusable one is dropped, not refused.
+  const bias = '30.1,-97.9|30.4,-97.6';
+  assert.equal(geocodeBounds(new URLSearchParams({ bounds: bias })), bias);
+  for (const bounds of [
+    '',
+    '30.1,-97.9',
+    '30.1,-97.9|30.4',
+    'north,-97.9|30.4,-97.6',
+    '91,-97.9|30.4,-97.6',
+    '30.1,-181|30.4,-97.6',
+  ])
+    assert.equal(geocodeBounds(new URLSearchParams({ bounds })), null);
+});
+
+test('the geocode routes keep the key server-side and answer in Google shape', async () => {
+  const upstream = [];
+  const routes = installRoutes({
+    fetchImpl: async (url) => {
+      upstream.push(new URL(String(url)));
+      return {
+        ok: true,
+        json: async () => ({ status: 'OK', results: [{ place_id: 'fixture' }] }),
+      };
+    },
+  });
+  const forward = routes.get('/api/google/geocode');
+  const reverse = routes.get('/api/google/reverse-geocode');
+  assert.equal(typeof forward, 'function');
+  assert.equal(typeof reverse, 'function');
+
+  const forwarded = await invokeRoute(forward, {
+    url: '/?address=Austin&bounds=30.1,-97.9|30.4,-97.6',
+  });
+  assert.equal(forwarded.statusCode, 200);
+  assert.deepEqual(forwarded.body, {
+    status: 'OK',
+    results: [{ place_id: 'fixture' }],
+  });
+  assert.equal(upstream.at(-1).searchParams.get('address'), 'Austin');
+  assert.equal(upstream.at(-1).searchParams.get('bounds'), '30.1,-97.9|30.4,-97.6');
+  assert.equal(upstream.at(-1).searchParams.get('key'), 'server-secret');
+
+  const reversed = await invokeRoute(reverse, { url: '/?lat=30.27&lon=-97.74' });
+  assert.equal(reversed.statusCode, 200);
+  assert.equal(upstream.at(-1).searchParams.get('latlng'), '30.27,-97.74');
+  assert.equal(upstream.at(-1).searchParams.get('key'), 'server-secret');
+
+  // The key travels to Google, never back to the page that asked.
+  assert.ok(!JSON.stringify(forwarded.body).includes('server-secret'));
+  assert.ok(!JSON.stringify(reversed.body).includes('server-secret'));
+
+  // A malformed bias is dropped rather than forwarded.
+  await invokeRoute(forward, { url: '/?address=Austin&bounds=north' });
+  assert.equal(upstream.at(-1).searchParams.has('bounds'), false);
+});
+
+test('a bad or keyless geocode request never reaches Google', async () => {
+  const upstream = [];
+  const fetchImpl = async (url) => {
+    upstream.push(String(url));
+    return { ok: true, json: async () => ({ status: 'OK', results: [] }) };
+  };
+
+  const routes = installRoutes({ fetchImpl });
+  for (const [path, url] of [
+    ['/api/google/geocode', '/?address='],
+    ['/api/google/reverse-geocode', '/?lat=91&lon=-97.74'],
+  ]) {
+    const response = await invokeRoute(routes.get(path), { url });
+    assert.equal(response.statusCode, 400);
+    assert.deepEqual(response.body.results, []);
+    assert.equal(response.body.status, 'REQUEST_DENIED');
+  }
+
+  for (const path of ['/api/google/geocode', '/api/google/reverse-geocode']) {
+    const rejected = await invokeRoute(routes.get(path), {
+      method: 'POST',
+      url: '/?address=Austin&lat=30&lon=-97',
+    });
+    assert.equal(rejected.statusCode, 405);
+  }
+
+  // Keyless is an empty capability, not an outage: a 200 the browser adapters
+  // read as "this provider did not answer", so the chain moves on. It resolves
+  // ahead of validation, like the Places routes: with nothing configured there
+  // is no request to validate and no quota to protect.
+  const keyless = installRoutes({ apiKey: '  ', fetchImpl });
+  for (const path of ['/api/google/geocode', '/api/google/reverse-geocode'])
+    for (const url of ['/?address=Austin&lat=30&lon=-97', '/?address=&lat=91']) {
+      const response = await invokeRoute(keyless.get(path), { url });
+      assert.equal(response.statusCode, 200);
+      assert.equal(response.headers['cache-control'], 'no-store');
+      assert.deepEqual(response.body, {
+        configured: false,
+        status: 'REQUEST_DENIED',
+        results: [],
+        error: null,
+      });
+    }
+
+  assert.deepEqual(upstream, []);
+});