cachinglisted

# Caching Patterns Reference for caching in .NET APIs. Covers HybridCache (L1+L2), output caching, cache-aside, and IMemoryCache. Used by `dnp-planner` and `dnp-tdd-developer-hard`. ## Caching Options at a Glance | Option | Best For | Notes | |--------|----------|-------| | `HybridCache` | Application-level data (entities, computed results) | .NET 9+; L1 in-process + L2 distributed; stampede protection | | `IOutputCache` | HTTP response caching (full responses) | Middleware-level; `[OutputCache]` attribute or `.CacheOutput()` | | `IMemoryCache` | Single-node, simple key-value, no distributed requirement | No stampede protection; use `GetOrCreateAsync` | | `IDistributedCache` | Distributed session, custom serialization | Low-level; HybridCache wraps it | ## HybridCache (.NET 9+) HybridCache combines an in-process L1 cache (fast) with an optional L2 distributed cache (Redis, SQL). Built-in stampede protection: concurrent requests for the same key share one factory call. ### Package ```xml <PackageReference Include="Microsoft.Extensions.Caching.Hybrid" Version="9.*" /> <!-- Optional Redis L2: --> <PackageReference Include="Microsoft.Extensions.Caching.StackExchangeRedis" Version="9.*" /> ``` ### Registration ```csharp builder.Services.AddHybridCache(options => { options.DefaultEntryOptions = new HybridCacheEntryOptions { // How long entries live in both L1 and L2 Expiration = TimeSpan.FromMinutes(5), // L1 can expire sooner to reduce stal