feat(native): the app needs TREK 5.1.3 on the server and checks a remembered one once after the update

The fixes that keep the app's sign-in in the app live in the server's UI,
so an updated app on a 5.1.2 server still ended in the browser. The server now
reports nativeApi 2 and the app refuses anything below it, naming 5.1.3.

A server the app remembers from before is not loaded unchecked: the first
launch after the update shows the address screen filled in with it, says why
and checks it right away. A server that is new enough loads again with its
session; an older one gets the update hint.

client/src/native/serverAddress.test.ts

@@ -3,7 +3,7 @@ import { candidateUrls, probeDemo, probeServer, type ProbeResponse } from './ser
 
 const features = (
   url: string,
-  data: unknown = { bookingImport: false, aiParsing: false, nativeApp: true }
+  data: unknown = { bookingImport: false, aiParsing: false, nativeApp: true, nativeApi: 2 }
 ): ProbeResponse => ({ status: 200, data, url });
 
 describe('candidateUrls', () => {
@@ -26,13 +26,21 @@ describe('candidateUrls', () => {
 
 describe('probeServer', () => {
   it('accepts a server at the minimum native API version or above', async () => {
-    const data = { bookingImport: false, nativeApp: true, nativeApi: 1 };
-    const get = vi.fn().mockResolvedValue(features('https://trek.example.com/api/health/features', data));
-    expect(await probeServer('https://trek.example.com', get)).toEqual({ ok: true, url: 'https://trek.example.com' });
+    for (const nativeApi of [2, 3]) {
+      const data = { bookingImport: false, nativeApp: true, nativeApi };
+      const get = vi.fn().mockResolvedValue(features('https://trek.example.com/api/health/features', data));
+      expect(await probeServer('https://trek.example.com', get)).toEqual({ ok: true, url: 'https://trek.example.com' });
+    }
   });
 
   it('calls a server below the minimum native API version too old', async () => {
-    const data = { bookingImport: false, nativeApp: true, nativeApi: 0 };
+    const data = { bookingImport: false, nativeApp: true, nativeApi: 1 };
+    const get = vi.fn().mockResolvedValue(features('https://trek.example.com/api/health/features', data));
+    expect(await probeServer('https://trek.example.com', get)).toEqual({ ok: false, reason: 'tooOld' });
+  });
+
+  it('calls a server that speaks to the app but reports no native API version too old', async () => {
+    const data = { bookingImport: false, nativeApp: true };
     const get = vi.fn().mockResolvedValue(features('https://trek.example.com/api/health/features', data));
     expect(await probeServer('https://trek.example.com', get)).toEqual({ ok: false, reason: 'tooOld' });
   });
@@ -173,7 +181,7 @@ describe('probeServer behind mutual TLS', () => {
   });
 
   it('connects where the proxy asked and TREK answered, with or without a certificate', async () => {
-    const trek = { bookingImport: false, nativeApp: true, nativeApi: 1 };
+    const trek = { bookingImport: false, nativeApp: true, nativeApi: 2 };
     for (const sent of [true, false]) {
       const get = vi.fn().mockResolvedValue(asked(200, sent, trek));
       expect(await probeServer('https://trek.example.com', get)).toEqual({ ok: true, url: 'https://trek.example.com' });

client/src/native/serverAddress.ts

@@ -43,10 +43,12 @@ const FEATURES_PATH = '/api/health/features';
 
 /**
  * The oldest server API this app can work with (`nativeApi` in the features
- * response). A server from before the field existed answers without it and is
- * accepted while the minimum is 1.
+ * response). 2 is TREK 5.1.3, the first server whose sign-in from the app does
+ * not end in the browser. A server without the field is older still. Raising it
+ * goes with SERVER_CHECK in TrekServerStore (iOS and Android), so a server the
+ * app remembers from before is checked against the new minimum once.
  */
-const MIN_NATIVE_API = 1;
+export const MIN_NATIVE_API = 2;
 
 function normalize(raw: string): string | null {
   let parsed: URL;
@@ -80,7 +82,7 @@ function judge(response: ProbeResponse): ProbeResult {
   if (response.status !== 200 || !isRecord(response.data)) return { ok: false, reason: 'notTrek' };
   if (response.data.nativeApp === true) {
     const api = response.data.nativeApi;
-    if (typeof api === 'number' && api < MIN_NATIVE_API) return { ok: false, reason: 'tooOld' };
+    if (typeof api !== 'number' || api < MIN_NATIVE_API) return { ok: false, reason: 'tooOld' };
     // Follow a redirect (http to https, a canonical host) so the app loads the
     // address the server actually answers on.
     const base = response.url.endsWith(FEATURES_PATH) ? response.url.slice(0, -FEATURES_PATH.length) : null;

client/src/native/trekShell.ts

@@ -13,7 +13,12 @@ import type { NativeCapabilities } from './capabilities';
  * worker.
  */
 export interface TrekShellPlugin {
-  getServer(): Promise<{ url: string | null }>;
+  /**
+   * `previousUrl`: the server this app remembered before an update asked for a
+   * newer one (SERVER_CHECK in TrekServerStore). Set only while no server is,
+   * so the address screen can check it again, pre-filled.
+   */
+  getServer(): Promise<{ url: string | null; previousUrl?: string | null }>;
   /**
    * Remembers the server and loads it. The current page is gone afterwards.
    * `signInHosts` are the hosts of a proxy's sign-in page in front of it