diff --git a/.sisyphus/notepads/fingerprint-migration/decisions.md b/.sisyphus/notepads/fingerprint-migration/decisions.md
new file mode 100644
index 0000000..7a93271
--- /dev/null
+++ b/.sisyphus/notepads/fingerprint-migration/decisions.md
@@ -0,0 +1,8 @@
+## Migration Decisions
+
+- **Library**: `@isaacs/ttlcache` v2.1.4
+- **Rationale**: Minimal, zero-dependency, specialized for TTL, well-maintained.
+- **Cache Key**: Fixed string `'fingerprint'` since we only cache one result.
+- **Max Items**: 1 (singleton fingerprint).
+- **Default TTL**: 10 minutes (compatible with previous implementation).
+
diff --git a/.sisyphus/notepads/fingerprint-migration/learnings.md b/.sisyphus/notepads/fingerprint-migration/learnings.md
new file mode 100644
index 0000000..ac30154
--- /dev/null
+++ b/.sisyphus/notepads/fingerprint-migration/learnings.md
@@ -0,0 +1,8 @@
+## @isaacs/ttlcache Migration Learnings
+
+- Successfully replaced manual TTL cache with `@isaacs/ttlcache` in `fingerprint.ts`.
+- Use `catalog:` for dependency management in the Bun monorepo.
+- `TTLCache` does not handle in-flight request deduplication, so the `inFlight` Promise pattern was preserved.
+- Alphabetical sorting in `package.json` catalog is important for consistency.
+- Biome handles import organization and formatting; `bun fix` should be run after manual edits.
+
diff --git a/apps/server/AGENTS.md b/apps/server/AGENTS.md
index 9531692..8b583a3 100644
--- a/apps/server/AGENTS.md
+++ b/apps/server/AGENTS.md
@@ -346,6 +346,37 @@ const fingerprint = createHash('sha256')
 - 深入研究文档和源码再做技术决策
 - 区分"用户输入场景"和"系统数据场景"的安全要求
 
+### 缓存库选择：@isaacs/ttlcache
+
+**决策时间**: 2026-01-26
+
+**背景**：
+硬件指纹功能最初使用手动实现的 TTL 缓存（module-level 变量 + 手动过期检查）。为提高代码可维护性，迁移到专业缓存库。
+
+**选型**：
+- **选择**: `@isaacs/ttlcache` v2.1.4
+- **理由**:
+  - 专为 TTL 场景优化，无需 LRU 追踪开销
+  - 零依赖，6M+ 周下载量
+  - 内置 TypeScript 类型
+  - 自动过期管理，无需手动定时器
+  - API 简洁: `new TTLCache({ ttl, max })`
+
+**实现细节**：
+- 保留 `inFlight` Promise 模式用于并发请求去重（TTLCache 不提供此功能）
+- 使用单一缓存键 `'fingerprint'`（单服务器场景，opts 不影响输出）
+- 默认 TTL: 10 分钟（可通过 `cacheTtlMs` 参数覆盖）
+
+**对比手动实现**：
+- ✅ 更少自定义代码
+- ✅ 更清晰的 TTL 语义
+- ✅ 经过充分测试的库
+- ⚠️ 仍需手动处理并发去重
+
+**经验教训**：
+- 专业库不一定解决所有问题（如并发去重）
+- 对于简单场景，手动实现 vs 库的选择主要取决于可维护性而非功能
+
 ### Git 工作流要求
 
 **重要原则**：保持代码仓库与文档同步
diff --git a/apps/server/package.json b/apps/server/package.json
index 38ca4da..0529bb8 100644
--- a/apps/server/package.json
+++ b/apps/server/package.json
@@ -15,6 +15,7 @@
     "typecheck": "tsc --noEmit"
   },
   "dependencies": {
+    "@isaacs/ttlcache": "catalog:",
     "@orpc/client": "catalog:",
     "@orpc/contract": "catalog:",
     "@orpc/openapi": "catalog:",
diff --git a/apps/server/src/lib/fingerprint.ts b/apps/server/src/lib/fingerprint.ts
index 1ebd473..0dec22b 100644
--- a/apps/server/src/lib/fingerprint.ts
+++ b/apps/server/src/lib/fingerprint.ts
@@ -1,3 +1,4 @@
+import { TTLCache } from '@isaacs/ttlcache'
 import { hash } from 'ohash'
 import si from 'systeminformation'
 
@@ -63,10 +64,10 @@ export type HardwareFingerprintResult = {
 }
 
 // 缓存实例
-let cache: {
-  expiresAt: number
-  value: HardwareFingerprintResult
-} | null = null
+const cache = new TTLCache<'fingerprint', HardwareFingerprintResult>({
+  ttl: 10 * 60 * 1000, // 10 minutes default
+  max: 1, // Only one fingerprint cached
+})
 
 // 防止并发重复请求
 let inFlight: Promise<HardwareFingerprintResult> | null = null
@@ -182,8 +183,9 @@ export async function getHardwareFingerprint(
   const now = Date.now()
 
   // 返回缓存结果
-  if (cache && cache.expiresAt > now) {
-    return cache.value
+  const cached = cache.get('fingerprint')
+  if (cached) {
+    return cached
   }
 
   // 防止并发重复请求
@@ -212,7 +214,7 @@ export async function getHardwareFingerprint(
     }
 
     // 更新缓存
-    cache = { expiresAt: now + ttl, value: result }
+    cache.set('fingerprint', result, { ttl })
 
     return result
   })().finally(() => {
@@ -226,6 +228,6 @@ export async function getHardwareFingerprint(
  * 清除指纹缓存(用于测试或强制刷新)
  */
 export function clearFingerprintCache(): void {
-  cache = null
+  cache.clear()
   inFlight = null
 }
diff --git a/bun.lock b/bun.lock
index 3bb6c49..a8a6d7f 100644
--- a/bun.lock
+++ b/bun.lock
@@ -13,6 +13,7 @@
       "name": "@furtherverse/server",
       "version": "1.0.0",
       "dependencies": {
+        "@isaacs/ttlcache": "catalog:",
         "@orpc/client": "catalog:",
         "@orpc/contract": "catalog:",
         "@orpc/openapi": "catalog:",
@@ -64,6 +65,7 @@
     "@biomejs/biome": "^2.3.11",
     "@effect/platform": "^0.94.2",
     "@effect/schema": "^0.75.5",
+    "@isaacs/ttlcache": "^2.1.4",
     "@orpc/client": "^1.13.4",
     "@orpc/contract": "^1.13.4",
     "@orpc/openapi": "^1.13.4",
@@ -234,6 +236,8 @@
 
     "@furtherverse/tsconfig": ["@furtherverse/tsconfig@workspace:packages/tsconfig"],
 
+    "@isaacs/ttlcache": ["@isaacs/ttlcache@2.1.4", "", {}, "sha512-7kMz0BJpMvgAMkyglums7B2vtrn5g0a0am77JY0GjkZZNetOBCFn7AG7gKCwT0QPiXyxW7YIQSgtARknUEOcxQ=="],
+
     "@jridgewell/gen-mapping": ["@jridgewell/gen-mapping@0.3.13", "", { "dependencies": { "@jridgewell/sourcemap-codec": "^1.5.0", "@jridgewell/trace-mapping": "^0.3.24" } }, "sha512-2kkt/7niJ6MgEPxF0bYdQ6etZaA+fQvDcLKckhy1yIQOzaoKjBBjSj63/aLVjYE3qhRt5dvM+uUyfCg6UKCBbA=="],
 
     "@jridgewell/remapping": ["@jridgewell/remapping@2.3.5", "", { "dependencies": { "@jridgewell/gen-mapping": "^0.3.5", "@jridgewell/trace-mapping": "^0.3.24" } }, "sha512-LI9u/+laYG4Ds1TDKSJW2YPrIlcVYOwi2fUC6xB43lueCjgxV4lffOCZCtYFiH6TNOX+tQKXx97T4IKHbhyHEQ=="],
diff --git a/package.json b/package.json
index 349b0e6..f0b5e8e 100644
--- a/package.json
+++ b/package.json
@@ -23,6 +23,7 @@
     "@biomejs/biome": "^2.3.11",
     "@effect/platform": "^0.94.2",
     "@effect/schema": "^0.75.5",
+    "@isaacs/ttlcache": "^2.1.4",
     "@orpc/client": "^1.13.4",
     "@orpc/contract": "^1.13.4",
     "@orpc/openapi": "^1.13.4",