feat(session): add configurable max concurrent sessions per user with…

src/config/env.validation.ts

@@ -94,6 +94,8 @@ export const envValidationSchema = Joi.object({
   SESSION_LOCK_TTL_MS: Joi.number().integer().default(5000),
   SESSION_LOCK_MAX_RETRIES: Joi.number().integer().default(5),
   SESSION_LOCK_RETRY_DELAY_MS: Joi.number().integer().default(120),
+  // Maximum concurrent sessions per user (default 5)
+  MAX_SESSIONS_PER_USER: Joi.number().integer().min(0).default(5),
   STICKY_SESSIONS_REQUIRED: Joi.boolean().default(true),
   TRUST_PROXY: Joi.boolean().default(true),
 

src/session/session.service.ts

@@ -25,12 +25,14 @@
   private readonly lockTtlMs: number;
   private readonly lockRetries: number;
   private readonly lockRetryDelayMs: number;
+  private readonly maxSessionsPerUser: number;
 
   constructor(
     @Inject(SESSION_REDIS_CLIENT) private readonly redis: Redis,
     private readonly configService: ConfigService,
   ) {
     this.sessionPrefix = this.configService.get<string>('AUTH_SESSION_PREFIX') || 'auth:sess:';
+    this.maxSessionsPerUser = parseInt(this.configService.get<string>('MAX_SESSIONS_PER_USER') || '5', 10);
     this.legacySessionPrefix =
       this.configService.get<string>('AUTH_SESSION_LEGACY_PREFIX') || 'session:';
     this.sessionTtlSeconds = parseInt(
@@ -119,7 +121,7 @@
       'EX',
       this.sessionTtlSeconds,
     );
-    await this.addSessionToUserIndex(userId, sid);
+await this.addSessionToUserIndex(userId, sid);
     return sid;
   }
 
@@ -183,7 +185,13 @@
     let deletedCount = 0;
 
     do {
-      const [nextCursor, keys] = await this.redis.scan(cursor, 'MATCH', pattern, 'COUNT', 100);
+      const [nextCursor, keys] = await this.redis.scan(
+        cursor,
+        'MATCH',
+        pattern,
+        'COUNT',
+        100,
+      );
       cursor = nextCursor;
 
       for (const key of keys) {
@@ -240,10 +248,18 @@
     };
 
     await this.redis
-      .multi()
-      .set(this.sessionKey(newSid), JSON.stringify(migrated), 'EX', this.sessionTtlSeconds)
-      .del(this.sessionKey(oldSid))
-      .exec();
+        .multi()
+        .set(this.sessionKey(newSid), JSON.stringify(migrated), 'EX', this.sessionTtlSeconds)
+        .del(this.sessionKey(oldSid))
+        .exec();
+      // Update user's session sorted set
+      if (existing) {
+        const userKey = this.userSessionKey(existing.userId);
+        await this.redis.multi()
+          .zrem(userKey, oldSid)
+          .zadd(userKey, Date.now(), newSid)
+          .exec();
+      }
 
     return newSid;
   }
@@ -328,6 +344,10 @@
     await this.redis.eval(releaseScript, 1, lockKey, lockToken);
   }
 
+  private userSessionKey(userId: string): string {
+    return `user:sessions:${userId}`;
+  }
+
   private sessionKey(sid: string): string {
     return `${this.sessionPrefix}${sid}`;
   }