Simplify connection flow, mobile transfer UI, and header actions

apps/server/src/service.ts

@@ -5,7 +5,8 @@ import { Storage } from './storage.js';
 import { ResumableUploads } from './resumable.js';
 import { NearbyLocations } from './nearby.js';
 import { Vault } from './vault.js';
-import { randomInt, randomUUID } from 'node:crypto';
+import { randomUUID } from 'node:crypto';
+import { newInviteCode } from './inviteCode.js';
 import { and, eq, gt, isNull, or, desc, lt, inArray, sql } from 'drizzle-orm';
 import type { DB } from './db/index.js';
 import * as s from './db/schema.js';
@@ -380,8 +381,18 @@ export class Service {
     const now = Date.now(),
       id = randomUUID(),
       token = randomToken();
-    const alphabet = 'ABCDEFGHJKLMNPQRSTUVWXYZ23456789';
-    const code = Array.from({ length: 8 }, () => alphabet[randomInt(alphabet.length)]).join('');
+    // The unique DB constraint includes historical spaces; never reuse their codes.
+    const code =
+      newInviteCode(this.cfg.spaceInviteCodeLength, (candidate: string) =>
+        Boolean(
+          this.db
+            .select({ id: s.spaces.id })
+            .from(s.spaces)
+            .where(eq(s.spaces.codeHash, hmac(this.cfg.discoverySecret, candidate)))
+            .get(),
+        ),
+      ) ??
+      fail(503, 'SPACE_CODE_BUSY', '초대 코드를 만들지 못했습니다. 잠시 후 다시 시도해 주세요.');
     this.db.transaction(() => {
       this.db
         .insert(s.spaces)