fix(relay): name the regional relay in pairing links without a code

changelog.d/relay-link-regional.md

@@ -0,0 +1,3 @@
+### Fixed
+- A pairing link without a code (pairing by comparing digits) now names the PC's regional relay, as
+  its QR code does, so the phone connects through the nearby relay from the start.

docs/relay.md

@@ -624,8 +624,9 @@ them; the list is `REGIONAL_RELAYS` in [`shared/relay-regions.ts`](../shared/rel
   A PC with `OVIS_RELAY_URL` set uses that relay alone, unless it names one of Ovis's regional
   relays: that one is used with no measuring, and beside `relay.ovis.sh`, as below.
 - **It stays on both.** The PC keeps its link to `relay.ovis.sh` and opens a second one, with the
-  same key and proof, to the regional relay. New pairing QR codes name the regional relay while its
-  link is online (the global one otherwise), and the relay status is the global link's. Each link
+  same key and proof, to the regional relay. New pairing QR codes and pairing links without a code
+  name the regional relay while its link is online (the global one otherwise), and the relay status
+  is the global link's. Each link
   has its own session limits.
 - **It tells phones paired before.** A phone that offers `relay-hints` is told in `AUTH_OK` the
   relay new offers name, then `relay.ovis.sh`, and saves the first for that PC; the app uses it from

server/relay/service.contract.test.ts

@@ -702,7 +702,8 @@ async function regionalFixture({ rtt = { global: 130, regional: 13 } as { global
   const base = `http://127.0.0.1:${app.port}`;
   const post = (path: string) => fetch(`${base}/api/relay${path}`, { method: "POST", headers: { origin: base, "x-herdr-update": "1" } });
   return { dir, relays, synced, lost, probed, signals, service, post,
-    async offer() { return decodeOffer(((await (await post("/offer")).json()) as { url: string }).url)!; } };
+    async offer() { return decodeOffer(((await (await post("/offer")).json()) as { url: string }).url)!; },
+    async link() { return decodeOffer(((await (await post("/link")).json()) as { url: string }).url)!; } };
 }
 
 it("advertises a regional relay that answers much faster, stays on the global one too, and keeps the choice", async () => {
@@ -759,6 +760,24 @@ it("keeps no measurement that finishes after the relay was turned off", async ()
   expect(f.service.status()).toMatchObject({ phase: "off", relay: "wss://global.test" });
 });
 
+it("names the relay new offers name in a pairing link without a code too", async () => {
+  // Given a PC that chose a regional relay
+  const f = await regionalFixture();
+  expect((await f.post("/start")).status).toBe(200);
+  await bounded(Promise.all([f.synced.global.promise, f.synced.regional.promise]));
+  // Then a link for comparing digits names the regional relay, as a QR code does
+  expect((await f.link()).relay).toBe("wss://regional.test");
+  // And the global relay while the regional link is down
+  await f.relays.regional.stop();
+  await bounded(f.lost.regional.promise);
+  expect((await f.link()).relay).toBe("wss://global.test");
+  // And a PC that chose no regional relay names the global one
+  const plain = await regionalFixture({ rtt: { global: 100, regional: 60 } });
+  expect((await plain.post("/start")).status).toBe(200);
+  await bounded(plain.synced.global.promise);
+  expect((await plain.link()).relay).toBe("wss://global.test");
+});
+
 it("names the global relay in new offers while the regional link is down, and reports the global link's state", async () => {
   // Given a PC on both relays
   const f = await regionalFixture();

server/relay/service.ts

@@ -262,7 +262,7 @@ export class RelayService {
   pairingLink(): { url: string } {
     if (!this.enabled || !this.identity || !this.services || this.blocked) throw new Error("Start the relay before pairing.");
     this.approvals.openWindow();
-    return { url: encodeOffer({ v: 1, server_id: this.identity.server_id, server_public_key: this.identity.public_key, relay: this.relay }, this.app) };
+    return { url: encodeOffer({ v: 1, server_id: this.identity.server_id, server_public_key: this.identity.public_key, relay: this.advertised }, this.app) };
   }
 
   async resetIdentity(): Promise<RelayStatus> {