fix(federation): persist remote instance_name from /peer/initiate handshake response

Mirrors the previous performHandshake fix for the admin-initiated path. /peer/initiate now parses the remote's instanceName from the /peer/accept response body and writes it alongside status='active'.

packages/server/src/routes/federation.peerAccept.test.ts

@@ -1,4 +1,4 @@
-import { describe, it, expect, beforeEach, vi } from 'vitest';
+import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
 import Fastify, { type FastifyInstance } from 'fastify';
 import Database from 'better-sqlite3';
 import { drizzle } from 'drizzle-orm/better-sqlite3';
@@ -298,3 +298,60 @@ describe('POST /api/federation/peer/accept — response body carries instanceNam
     expect(body.instanceName).toBeNull();
   });
 });
+
+describe('POST /api/federation/peer/initiate — persists remote instanceName from handshake response', () => {
+  let app: FastifyInstance;
+
+  beforeEach(async () => {
+    sqlite = new Database(':memory:');
+    testDb = drizzle(sqlite, { schema });
+    applyMigrations(sqlite);
+    seedInstanceSettings('Local Backspace');
+    app = await buildApp();
+  });
+
+  afterEach(() => {
+    vi.unstubAllGlobals();
+  });
+
+  it('writes remote.instanceName when remote /peer/accept succeeds', async () => {
+    vi.stubGlobal('fetch', vi.fn(async () =>
+      new Response(JSON.stringify({ accepted: true, instanceName: 'Remote Backspace' }), {
+        status: 200,
+        headers: { 'content-type': 'application/json' },
+      }),
+    ));
+
+    const response = await app.inject({
+      method: 'POST',
+      url: '/api/federation/peer/initiate',
+      payload: { remoteOrigin: 'https://remote.example' },
+    });
+
+    expect(response.statusCode).toBe(200);
+    const row = testDb.select().from(schema.federationPeers)
+      .where(eq(schema.federationPeers.origin, 'https://remote.example')).get();
+    expect(row?.status).toBe('active');
+    expect(row?.instanceName).toBe('Remote Backspace');
+  });
+
+  it('writes null instanceName when remote response omits the field', async () => {
+    vi.stubGlobal('fetch', vi.fn(async () =>
+      new Response(JSON.stringify({ accepted: true }), {
+        status: 200,
+        headers: { 'content-type': 'application/json' },
+      }),
+    ));
+
+    const response = await app.inject({
+      method: 'POST',
+      url: '/api/federation/peer/initiate',
+      payload: { remoteOrigin: 'https://remote.example' },
+    });
+
+    expect(response.statusCode).toBe(200);
+    const row = testDb.select().from(schema.federationPeers)
+      .where(eq(schema.federationPeers.origin, 'https://remote.example')).get();
+    expect(row?.instanceName).toBeNull();
+  });
+});

packages/server/src/routes/federation.ts

@@ -351,9 +351,21 @@ export async function federationRoutes(app: FastifyInstance): Promise<void> {
           return reply.code(502).send({ error: errorMessage, statusCode: 502 });
         }
 
-        // Remote accepted — activate the peer
+        // Remote accepted — activate the peer. Parse the remote's instanceName
+        // from the response body so the federation panel renders a friendly
+        // label. Tolerate omission and non-JSON bodies.
+        let remoteInstanceName: string | null = null;
+        try {
+          const body = (await response.json()) as { instanceName?: string | null };
+          if (typeof body?.instanceName === 'string' && body.instanceName.length > 0) {
+            remoteInstanceName = body.instanceName;
+          }
+        } catch {
+          // Non-JSON body — leave null.
+        }
+
         db.update(schema.federationPeers)
-          .set({ status: 'active', lastSeenAt: Date.now() })
+          .set({ status: 'active', lastSeenAt: Date.now(), instanceName: remoteInstanceName })
           .where(eq(schema.federationPeers.id, peerId))
           .run();
         connectionManager.sendToAdmins({ type: 'federation_peers_changed' as const });