現場でこれすげぇって感心した実装

import type { Cache } from "cache-manager";

export class InMemoryCacheManager {
  public constructor(
    private readonly cache: Cache,
    private readonly groupName: string = "",
  ) {}

  public async get<T>(key: string): Promise<T | undefined> {
    return await this.cache.get<T>(this.buildGroupKey(this.groupName, key));
  }

  public async set<T>(
    key: string,
    value: T,
    ttlSeconds?: number,
  ): Promise<void> {
    await this.cache.set(
      this.buildGroupKey(this.groupName, key),
      value,
      ttlSeconds,
    );
  }

  // ...

  public group(name: string): CacheManager {
    return new InMemoryCacheManager(
      this.cache,
      this.buildGroupKey(this.groupName, name),
    );
  }

  private buildGroupKey(groupName: string, key: string): string {
    return groupName ? `${groupName}.${key}` : key;
  }
}