Upgrade ExtendedCache with support for named caches (#6591)

* Upgrade ExtendedCache with support for named caches

* Addressed Claude PR suggestions - defensive mux creation, defend empty cache name, added tests

* Addressed PR suggestions; Fixed issue where IDistributedCache was missing when using the shared route; Added more unit tests

* Revert to TryAdd, document expectation that AddDistributedCache is called first

src/Core/Settings/GlobalSettings.cs

@@ -783,7 +783,18 @@ public class GlobalSettings : IGlobalSettings
     {
         public virtual IConnectionStringSettings Redis { get; set; } = new ConnectionStringSettings();
         public virtual IConnectionStringSettings Cosmos { get; set; } = new ConnectionStringSettings();
+        public ExtendedCacheSettings DefaultExtendedCache { get; set; } = new ExtendedCacheSettings();
+    }
 
+    /// <summary>
+    /// A collection of Settings for customizing the FusionCache used in extended caching. Defaults are
+    /// provided for every attribute so that only specific values need to be overridden if needed.
+    /// </summary>
+    public class ExtendedCacheSettings
+    {
+        public bool EnableDistributedCache { get; set; } = true;
+        public bool UseSharedRedisCache { get; set; } = true;
+        public IConnectionStringSettings Redis { get; set; } = new ConnectionStringSettings();
         public TimeSpan Duration { get; set; } = TimeSpan.FromMinutes(30);
         public bool IsFailSafeEnabled { get; set; } = true;
         public TimeSpan FailSafeMaxDuration { get; set; } = TimeSpan.FromHours(2);

src/Core/Utilities/ExtendedCacheServiceCollectionExtensions.cs

@@ -3,6 +3,7 @@ using Bit.Core.Utilities;
 using Microsoft.Extensions.Caching.Distributed;
 using Microsoft.Extensions.Caching.StackExchangeRedis;
 using Microsoft.Extensions.DependencyInjection.Extensions;
+using Microsoft.Extensions.Logging;
 using StackExchange.Redis;
 using ZiggyCreatures.Caching.Fusion;
 using ZiggyCreatures.Caching.Fusion.Backplane;
@@ -14,70 +15,84 @@ namespace Microsoft.Extensions.DependencyInjection;
 public static class ExtendedCacheServiceCollectionExtensions
 {
     /// <summary>
-    /// Add Fusion Cache <see href="https://github.com/ZiggyCreatures/FusionCache"/> to the service
+    /// Adds a new, named Fusion Cache <see href="https://github.com/ZiggyCreatures/FusionCache"/> to the service
-    /// collection.<br/>
+    /// collection. If an existing cache of the same name is found, it will do nothing.<br/>
     /// <br/>
-    /// If Redis is configured, it uses Redis for an L2 cache and backplane. If not, it simply uses in-memory caching.
+    /// <b>Note</b>: When re-using the existing Redis cache, it is expected to call this method <b>after</b> calling
+    /// <code>services.AddDistributedCache(globalSettings)</code><br />This ensures that DI correctly finds,
+    /// configures, and re-uses all the shared Redis architecture.
     /// </summary>
-    public static IServiceCollection TryAddExtendedCacheServices(this IServiceCollection services, GlobalSettings globalSettings)
+    public static IServiceCollection AddExtendedCache(
+        this IServiceCollection services,
+        string cacheName,
+        GlobalSettings globalSettings,
+        GlobalSettings.ExtendedCacheSettings? settings = null)
     {
-        if (services.Any(s => s.ServiceType == typeof(IFusionCache)))
+        settings ??= globalSettings.DistributedCache.DefaultExtendedCache;
+        if (settings is null || string.IsNullOrEmpty(cacheName))
         {
             return services;
         }
 
-        var fusionCacheBuilder = services.AddFusionCache()
+        // If a cache already exists with this key, do nothing
-            .WithOptions(options =>
+        if (services.Any(s => s.ServiceType == typeof(IFusionCache) &&
+                         s.ServiceKey?.Equals(cacheName) == true))
         {
-                options.DistributedCacheCircuitBreakerDuration = globalSettings.DistributedCache.DistributedCacheCircuitBreakerDuration;
+            return services;
+        }
+
+        if (services.All(s => s.ServiceType != typeof(FusionCacheSystemTextJsonSerializer)))
+        {
+            services.AddFusionCacheSystemTextJsonSerializer();
+        }
+        var fusionCacheBuilder = services
+            .AddFusionCache(cacheName)
+            .WithCacheKeyPrefix($"{cacheName}:")
+            .AsKeyedServiceByCacheName()
+            .WithOptions(opt =>
+            {
+                opt.DistributedCacheCircuitBreakerDuration = settings.DistributedCacheCircuitBreakerDuration;
             })
             .WithDefaultEntryOptions(new FusionCacheEntryOptions
             {
-                Duration = globalSettings.DistributedCache.Duration,
+                Duration = settings.Duration,
-                IsFailSafeEnabled = globalSettings.DistributedCache.IsFailSafeEnabled,
+                IsFailSafeEnabled = settings.IsFailSafeEnabled,
-                FailSafeMaxDuration = globalSettings.DistributedCache.FailSafeMaxDuration,
+                FailSafeMaxDuration = settings.FailSafeMaxDuration,
-                FailSafeThrottleDuration = globalSettings.DistributedCache.FailSafeThrottleDuration,
+                FailSafeThrottleDuration = settings.FailSafeThrottleDuration,
-                EagerRefreshThreshold = globalSettings.DistributedCache.EagerRefreshThreshold,
+                EagerRefreshThreshold = settings.EagerRefreshThreshold,
-                FactorySoftTimeout = globalSettings.DistributedCache.FactorySoftTimeout,
+                FactorySoftTimeout = settings.FactorySoftTimeout,
-                FactoryHardTimeout = globalSettings.DistributedCache.FactoryHardTimeout,
+                FactoryHardTimeout = settings.FactoryHardTimeout,
-                DistributedCacheSoftTimeout = globalSettings.DistributedCache.DistributedCacheSoftTimeout,
+                DistributedCacheSoftTimeout = settings.DistributedCacheSoftTimeout,
-                DistributedCacheHardTimeout = globalSettings.DistributedCache.DistributedCacheHardTimeout,
+                DistributedCacheHardTimeout = settings.DistributedCacheHardTimeout,
-                AllowBackgroundDistributedCacheOperations = globalSettings.DistributedCache.AllowBackgroundDistributedCacheOperations,
+                AllowBackgroundDistributedCacheOperations = settings.AllowBackgroundDistributedCacheOperations,
-                JitterMaxDuration = globalSettings.DistributedCache.JitterMaxDuration
+                JitterMaxDuration = settings.JitterMaxDuration
             })
-            .WithSerializer(
+            .WithRegisteredSerializer();
-                new FusionCacheSystemTextJsonSerializer()
+
-            );
+        if (!settings.EnableDistributedCache)
+            return services;
+
+        if (settings.UseSharedRedisCache)
+        {
+            // Using Shared Redis, TryAdd and reuse all pieces (multiplexer, distributed cache and backplane)
 
             if (!CoreHelpers.SettingHasValue(globalSettings.DistributedCache.Redis.ConnectionString))
-        {
                 return services;
-        }
 
             services.TryAddSingleton<IConnectionMultiplexer>(sp =>
-            ConnectionMultiplexer.Connect(globalSettings.DistributedCache.Redis.ConnectionString));
+                CreateConnectionMultiplexer(sp, cacheName, globalSettings.DistributedCache.Redis.ConnectionString));
 
-        fusionCacheBuilder
+            services.TryAddSingleton<IDistributedCache>(sp =>
-            .WithDistributedCache(sp =>
             {
-                var cache = sp.GetService<IDistributedCache>();
-                if (cache is not null)
-                {
-                    return cache;
-                }
                 var mux = sp.GetRequiredService<IConnectionMultiplexer>();
                 return new RedisCache(new RedisCacheOptions
                 {
                     ConnectionMultiplexerFactory = () => Task.FromResult(mux)
                 });
-            })
+            });
-            .WithBackplane(sp =>
+
+            services.TryAddSingleton<IFusionCacheBackplane>(sp =>
                 {
-                var backplane = sp.GetService<IFusionCacheBackplane>();
-                if (backplane is not null)
-                {
-                    return backplane;
-                }
                     var mux = sp.GetRequiredService<IConnectionMultiplexer>();
                     return new RedisBackplane(new RedisBackplaneOptions
                     {
@@ -85,6 +100,64 @@ public static class ExtendedCacheServiceCollectionExtensions
                     });
                 });
 
+            fusionCacheBuilder
+                .WithRegisteredDistributedCache()
+                .WithRegisteredBackplane();
+
             return services;
         }
+
+        // Using keyed Redis / Distributed Cache. Create all pieces as keyed services.
+
+        if (!CoreHelpers.SettingHasValue(settings.Redis.ConnectionString))
+            return services;
+
+        services.TryAddKeyedSingleton<IConnectionMultiplexer>(
+            cacheName,
+            (sp, _) => CreateConnectionMultiplexer(sp, cacheName, settings.Redis.ConnectionString)
+        );
+        services.TryAddKeyedSingleton<IDistributedCache>(
+            cacheName,
+            (sp, _) =>
+            {
+                var mux = sp.GetRequiredKeyedService<IConnectionMultiplexer>(cacheName);
+                return new RedisCache(new RedisCacheOptions
+                {
+                    ConnectionMultiplexerFactory = () => Task.FromResult(mux)
+                });
+            }
+        );
+        services.TryAddKeyedSingleton<IFusionCacheBackplane>(
+            cacheName,
+            (sp, _) =>
+            {
+                var mux = sp.GetRequiredKeyedService<IConnectionMultiplexer>(cacheName);
+                return new RedisBackplane(new RedisBackplaneOptions
+                {
+                    ConnectionMultiplexerFactory = () => Task.FromResult(mux)
+                });
+            }
+        );
+
+        fusionCacheBuilder
+            .WithRegisteredKeyedDistributedCacheByCacheName()
+            .WithRegisteredKeyedBackplaneByCacheName();
+
+        return services;
+    }
+
+    private static ConnectionMultiplexer CreateConnectionMultiplexer(IServiceProvider sp, string cacheName,
+        string connectionString)
+    {
+        try
+        {
+            return ConnectionMultiplexer.Connect(connectionString);
+        }
+        catch (Exception ex)
+        {
+            var logger = sp.GetService<ILogger>();
+            logger?.LogError(ex, "Failed to connect to Redis for cache {CacheName}", cacheName);
+            throw;
+        }
+    }
 }

src/Core/Utilities/README.md

@@ -0,0 +1,157 @@
+## Extended Cache
+
+`ExtendedCache` is a wrapper around [FusionCache](https://github.com/ZiggyCreatures/FusionCache)
+that provides a simple way to register **named, isolated caches** with sensible defaults.
+The goal is to make it trivial for each subsystem or feature to have its own cache -
+with optional distributed caching and backplane support - without repeatedly wiring up
+FusionCache, Redis, and related infrastructure.
+
+Each named cache automatically receives:
+
+- Its own `FusionCache` instance
+- Its own configuration (default or overridden)
+- Its own key prefix
+- Optional distributed store
+- Optional backplane
+
+`ExtendedCache` supports several deployment modes:
+
+- **Memory-only caching** (with stampede protection)
+- **Memory + distributed cache + backplane** using the **shared** application Redis
+- **Memory + distributed cache + backplane** using a **fully isolated** Redis instance
+
+**Note**: When using the shared Redis cache option (which is on by default, if the
+Redis connection string is configured), it is expected to call
+`services.AddDistributedCache(globalSettings)` **before** calling
+`AddExtendedCache`. The idea is to set up the distributed cache in our normal pattern
+and then "extend" it to include more functionality.
+
+### Configuration
+
+`ExtendedCache` exposes a set of default properties that define how each named cache behaves.
+These map directly to FusionCache configuration options such as timeouts, duration,
+jitter, fail-safe mode, etc. Any cache can override these defaults independently.
+
+#### Default configuration
+
+The simplest approach registers a new named cache with default settings and reusing
+the existing distributed cache:
+
+``` csharp
+    services.AddDistributedCache(globalSettings);
+    services.AddExtendedCache(cacheName, globalSettings);
+```
+
+By default:
+ - If `GlobalSettings.DistributedCache.Redis.ConnectionString` is configured:
+   - The cache is memory + distributed (Redis)
+   - The Redis cache created by `AddDistributedCache` is re-used
+   - A Redis backplane is configured, re-using the same multiplexer
+ - If Redis is **not** configured the cache automatically falls back to memory-only
+
+#### Overriding default properties
+
+A number of default properties are provided (see
+`GlobalSettings.DistributedCache.DefaultExtendedCache` for specific values). A named
+cache can override any (or all) of these properties simply by providing its own
+instance of `ExtendedCacheSettings`:
+
+``` csharp
+    services.AddExtendedCache(cacheName, globalSettings, new GlobalSettings.ExtendedCacheSettings
+        {
+            Duration = TimeSpan.FromHours(1),
+        });
+```
+
+This example keeps all other defaults—including shared Redis—but changes the
+default cached item duration from 30 minutes to 1 hour.
+
+#### Isolated Redis configuration
+
+ExtendedCache can also run in a fully isolated mode where the cache uses its own:
+ - Redis multiplexer
+ - Distributed cache
+ - Backplane
+
+To enable this, specify a Redis connection string and set `UseSharedRedisCache`
+to `false`:
+
+``` csharp
+    services.AddExtendedCache(cacheName, globalSettings, new GlobalSettings.ExtendedCacheSettings
+        {
+            UseSharedRedisCache = false,
+            Redis = new GlobalSettings.ConnectionStringSettings { ConnectionString = "localhost:6379" }
+        });
+```
+
+When configured this way:
+ - A dedicated `IConnectionMultiplexer` is created
+ - A dedicated `IDistributedCache` is created
+ - A dedicated FusionCache backplane is created
+ - All three are exposed to DI as keyed services (using the cache name as service key)
+
+### Accessing a named cache
+
+A named cache can be retrieved either:
+ - Directly via DI using keyed services
+ - Through `IFusionCacheProvider` (similar to
+   [IHttpClientFactory](https://learn.microsoft.com/en-us/aspnet/core/fundamentals/http-requests?view=aspnetcore-7.0#named-clients))
+
+#### Keyed service
+
+In the consuming class, declare an IFusionCache field:
+
+```csharp
+    private IFusionCache _cache;
+```
+
+Then ask DI to inject the keyed cache:
+
+```csharp
+    public MyService([FromKeyedServices("MyCache")] IFusionCache cache)
+    {
+        _cache = cache;
+    }
+```
+
+Or request it manually:
+
+```csharp
+    cache: provider.GetRequiredKeyedService<IFusionCache>(serviceKey: cacheName)
+```
+
+#### Injecting a provider
+
+Alternatively, an `IFusionCacheProvider` can be injected and used to request a named
+cache - similar to how `IHttpClientFactory` can be used to create named `HttpClient`
+instances
+
+In the class using the cache, use an injected provider to request the named cache:
+
+```csharp
+    private readonly IFusionCache _cache;
+
+    public MyController(IFusionCacheProvider cacheProvider)
+    {
+        _cache = cacheProvider.GetCache("CacheName");
+    }
+```
+
+### Using a cache
+
+Using the cache in code is as simple as replacing the direct repository calls with
+`FusionCache`'s `GetOrSet` call. If the class previously fetched an `Item` from
+an `ItemRepository`, all that we need to do is provide a key and the original
+repository call as the fallback:
+
+```csharp
+        var item = _cache.GetOrSet<Item>(
+            $"item:{id}",
+            _ => _itemRepository.GetById(id)
+        );
+```
+
+`ExtendedCache` doesn’t change how `FusionCache` is used in code, which means all
+the functionality and full `FusionCache` API is available. See the
+[FusionCache docs](https://github.com/ZiggyCreatures/FusionCache/blob/main/docs/CoreMethods.md)
+for more details.

test/Core.Test/Utilities/ExtendedCacheServiceCollectionExtensionsTests.cs

@@ -14,6 +14,7 @@ public class ExtendedCacheServiceCollectionExtensionsTests
 {
     private readonly IServiceCollection _services;
     private readonly GlobalSettings _globalSettings;
+    private const string _cacheName = "TestCache";
 
     public ExtendedCacheServiceCollectionExtensionsTests()
     {
@@ -33,129 +34,276 @@ public class ExtendedCacheServiceCollectionExtensionsTests
     }
 
     [Fact]
-    public void TryAddFusionCoreServices_CustomSettings_OverridesDefaults()
+    public void AddExtendedCache_CustomSettings_OverridesDefaults()
     {
-        var settings = CreateGlobalSettings(new Dictionary<string, string?>
+        var settings = new GlobalSettings.ExtendedCacheSettings
         {
-            { "GlobalSettings:DistributedCache:Duration", "00:12:00" },
+            Duration = TimeSpan.FromMinutes(12),
-            { "GlobalSettings:DistributedCache:FailSafeMaxDuration", "01:30:00" },
+            FailSafeMaxDuration = TimeSpan.FromHours(1.5),
-            { "GlobalSettings:DistributedCache:FailSafeThrottleDuration", "00:01:00" },
+            FailSafeThrottleDuration = TimeSpan.FromMinutes(1),
-            { "GlobalSettings:DistributedCache:EagerRefreshThreshold", "0.75" },
+            EagerRefreshThreshold = 0.75f,
-            { "GlobalSettings:DistributedCache:FactorySoftTimeout", "00:00:00.020" },
+            FactorySoftTimeout = TimeSpan.FromMilliseconds(20),
-            { "GlobalSettings:DistributedCache:FactoryHardTimeout", "00:00:03" },
+            FactoryHardTimeout = TimeSpan.FromSeconds(3),
-            { "GlobalSettings:DistributedCache:DistributedCacheSoftTimeout", "00:00:00.500" },
+            DistributedCacheSoftTimeout = TimeSpan.FromSeconds(0.5),
-            { "GlobalSettings:DistributedCache:DistributedCacheHardTimeout", "00:00:01.500" },
+            DistributedCacheHardTimeout = TimeSpan.FromSeconds(1.5),
-            { "GlobalSettings:DistributedCache:JitterMaxDuration", "00:00:05" },
+            JitterMaxDuration = TimeSpan.FromSeconds(5),
-            { "GlobalSettings:DistributedCache:IsFailSafeEnabled", "false" },
+            IsFailSafeEnabled = false,
-            { "GlobalSettings:DistributedCache:AllowBackgroundDistributedCacheOperations", "false" },
+            AllowBackgroundDistributedCacheOperations = false,
+        };
+
+        _services.AddExtendedCache(_cacheName, _globalSettings, settings);
+
+        using var provider = _services.BuildServiceProvider();
+        var cache = provider.GetRequiredKeyedService<IFusionCache>(_cacheName);
+        var opt = cache.DefaultEntryOptions;
+
+        Assert.Equal(TimeSpan.FromMinutes(12), opt.Duration);
+        Assert.False(opt.IsFailSafeEnabled);
+        Assert.Equal(TimeSpan.FromHours(1.5), opt.FailSafeMaxDuration);
+        Assert.Equal(TimeSpan.FromMinutes(1), opt.FailSafeThrottleDuration);
+        Assert.Equal(0.75f, opt.EagerRefreshThreshold);
+        Assert.Equal(TimeSpan.FromMilliseconds(20), opt.FactorySoftTimeout);
+        Assert.Equal(TimeSpan.FromMilliseconds(3000), opt.FactoryHardTimeout);
+        Assert.Equal(TimeSpan.FromSeconds(0.5), opt.DistributedCacheSoftTimeout);
+        Assert.Equal(TimeSpan.FromSeconds(1.5), opt.DistributedCacheHardTimeout);
+        Assert.False(opt.AllowBackgroundDistributedCacheOperations);
+        Assert.Equal(TimeSpan.FromSeconds(5), opt.JitterMaxDuration);
+    }
+
+    [Fact]
+    public void AddExtendedCache_DefaultSettings_ConfiguresExpectedValues()
+    {
+        _services.AddExtendedCache(_cacheName, _globalSettings);
+
+        using var provider = _services.BuildServiceProvider();
+        var cache = provider.GetRequiredKeyedService<IFusionCache>(_cacheName);
+        var opt = cache.DefaultEntryOptions;
+
+        Assert.Equal(TimeSpan.FromMinutes(30), opt.Duration);
+        Assert.True(opt.IsFailSafeEnabled);
+        Assert.Equal(TimeSpan.FromHours(2), opt.FailSafeMaxDuration);
+        Assert.Equal(TimeSpan.FromSeconds(30), opt.FailSafeThrottleDuration);
+        Assert.Equal(0.9f, opt.EagerRefreshThreshold);
+        Assert.Equal(TimeSpan.FromMilliseconds(100), opt.FactorySoftTimeout);
+        Assert.Equal(TimeSpan.FromMilliseconds(1500), opt.FactoryHardTimeout);
+        Assert.Equal(TimeSpan.FromSeconds(1), opt.DistributedCacheSoftTimeout);
+        Assert.Equal(TimeSpan.FromSeconds(2), opt.DistributedCacheHardTimeout);
+        Assert.True(opt.AllowBackgroundDistributedCacheOperations);
+        Assert.Equal(TimeSpan.FromSeconds(2), opt.JitterMaxDuration);
+    }
+
+    [Fact]
+    public void AddExtendedCache_DisabledDistributedCache_DoesNotRegisterBackplaneOrRedis()
+    {
+        var settings = new GlobalSettings.ExtendedCacheSettings
+        {
+            EnableDistributedCache = false,
+        };
+
+        _services.AddExtendedCache(_cacheName, _globalSettings, settings);
+
+        using var provider = _services.BuildServiceProvider();
+        var cache = provider.GetRequiredKeyedService<IFusionCache>(_cacheName);
+
+        Assert.False(cache.HasDistributedCache);
+        Assert.False(cache.HasBackplane);
+    }
+
+    [Fact]
+    public void AddExtendedCache_EmptyCacheName_DoesNothing()
+    {
+        _services.AddExtendedCache(string.Empty, _globalSettings);
+
+        var regs = _services.Where(s => s.ServiceType == typeof(IFusionCache)).ToList();
+        Assert.Empty(regs);
+
+        using var provider = _services.BuildServiceProvider();
+        var cache = provider.GetKeyedService<IFusionCache>(_cacheName);
+        Assert.Null(cache);
+    }
+
+    [Fact]
+    public void AddExtendedCache_MultipleCalls_OnlyAddsOneCacheService()
+    {
+        var settings = CreateGlobalSettings(new()
+        {
+            { "GlobalSettings:DistributedCache:Redis:ConnectionString", "localhost:6379" }
         });
 
-        _services.TryAddExtendedCacheServices(settings);
+        // Provide a multiplexer (shared)
-        using var provider = _services.BuildServiceProvider();
+        _services.AddSingleton(Substitute.For<IConnectionMultiplexer>());
-        var fusionCache = provider.GetRequiredService<IFusionCache>();
-        var options = fusionCache.DefaultEntryOptions;
 
-        Assert.Equal(TimeSpan.FromMinutes(12), options.Duration);
+        _services.AddExtendedCache(_cacheName, settings);
-        Assert.False(options.IsFailSafeEnabled);
+        _services.AddExtendedCache(_cacheName, settings);
-        Assert.Equal(TimeSpan.FromHours(1.5), options.FailSafeMaxDuration);
+        _services.AddExtendedCache(_cacheName, settings);
-        Assert.Equal(TimeSpan.FromMinutes(1), options.FailSafeThrottleDuration);
+
-        Assert.Equal(0.75f, options.EagerRefreshThreshold);
+        var regs = _services.Where(s => s.ServiceType == typeof(IFusionCache)).ToList();
-        Assert.Equal(TimeSpan.FromMilliseconds(20), options.FactorySoftTimeout);
+        Assert.Single(regs);
-        Assert.Equal(TimeSpan.FromMilliseconds(3000), options.FactoryHardTimeout);
+
-        Assert.Equal(TimeSpan.FromSeconds(0.5), options.DistributedCacheSoftTimeout);
+        using var provider = _services.BuildServiceProvider();
-        Assert.Equal(TimeSpan.FromSeconds(1.5), options.DistributedCacheHardTimeout);
+        var cache = provider.GetRequiredKeyedService<IFusionCache>(_cacheName);
-        Assert.False(options.AllowBackgroundDistributedCacheOperations);
+        Assert.NotNull(cache);
-        Assert.Equal(TimeSpan.FromSeconds(5), options.JitterMaxDuration);
     }
 
     [Fact]
-    public void TryAddFusionCoreServices_DefaultSettings_ConfiguresExpectedValues()
+    public void AddExtendedCache_MultipleDifferentCaches_AddsAll()
     {
-        _services.TryAddExtendedCacheServices(_globalSettings);
+        _services.AddExtendedCache("Cache1", _globalSettings);
+        _services.AddExtendedCache("Cache2", _globalSettings);
+
         using var provider = _services.BuildServiceProvider();
 
-        var fusionCache = provider.GetRequiredService<IFusionCache>();
+        var cache1 = provider.GetRequiredKeyedService<IFusionCache>("Cache1");
-        var options = fusionCache.DefaultEntryOptions;
+        var cache2 = provider.GetRequiredKeyedService<IFusionCache>("Cache2");
 
-        Assert.Equal(TimeSpan.FromMinutes(30), options.Duration);
+        Assert.NotNull(cache1);
-        Assert.True(options.IsFailSafeEnabled);
+        Assert.NotNull(cache2);
-        Assert.Equal(TimeSpan.FromHours(2), options.FailSafeMaxDuration);
+        Assert.NotSame(cache1, cache2);
-        Assert.Equal(TimeSpan.FromSeconds(30), options.FailSafeThrottleDuration);
-        Assert.Equal(0.9f, options.EagerRefreshThreshold);
-        Assert.Equal(TimeSpan.FromMilliseconds(100), options.FactorySoftTimeout);
-        Assert.Equal(TimeSpan.FromMilliseconds(1500), options.FactoryHardTimeout);
-        Assert.Equal(TimeSpan.FromSeconds(1), options.DistributedCacheSoftTimeout);
-        Assert.Equal(TimeSpan.FromSeconds(2), options.DistributedCacheHardTimeout);
-        Assert.True(options.AllowBackgroundDistributedCacheOperations);
-        Assert.Equal(TimeSpan.FromSeconds(2), options.JitterMaxDuration);
     }
 
     [Fact]
-    public void TryAddFusionCoreServices_MultipleCalls_OnlyConfiguresOnce()
+    public void AddExtendedCache_WithRedis_EnablesDistributedCacheAndBackplane()
     {
-        var settings = CreateGlobalSettings(new Dictionary<string, string?>
+        var settings = CreateGlobalSettings(new()
         {
             { "GlobalSettings:DistributedCache:Redis:ConnectionString", "localhost:6379" },
+            { "GlobalSettings:DistributedCache:DefaultExtendedCache:UseSharedRedisCache", "true" }
         });
-        _services.AddSingleton(Substitute.For<IConnectionMultiplexer>());
-        _services.TryAddExtendedCacheServices(settings);
-        _services.TryAddExtendedCacheServices(settings);
-        _services.TryAddExtendedCacheServices(settings);
 
-        var registrations = _services.Where(s => s.ServiceType == typeof(IFusionCache)).ToList();
+        // Provide a multiplexer (shared)
-        Assert.Single(registrations);
+        _services.AddSingleton(Substitute.For<IConnectionMultiplexer>());
+
+        _services.AddExtendedCache(_cacheName, settings);
 
         using var provider = _services.BuildServiceProvider();
-        var fusionCache = provider.GetRequiredService<IFusionCache>();
+        var cache = provider.GetRequiredKeyedService<IFusionCache>(_cacheName);
-        Assert.NotNull(fusionCache);
+
+        Assert.True(cache.HasDistributedCache);
+        Assert.True(cache.HasBackplane);
     }
 
     [Fact]
-    public void TryAddFusionCoreServices_WithRedis_EnablesDistributedCacheAndBackplane()
+    public void AddExtendedCache_InvalidRedisConnection_LogsAndThrows()
     {
-        var settings = CreateGlobalSettings(new Dictionary<string, string?>
+        var settings = new GlobalSettings.ExtendedCacheSettings
         {
-            { "GlobalSettings:DistributedCache:Redis:ConnectionString", "localhost:6379" },
+            UseSharedRedisCache = false,
-        });
+            Redis = new GlobalSettings.ConnectionStringSettings { ConnectionString = "invalid:9999" }
+        };
+
+        _services.AddExtendedCache(_cacheName, _globalSettings, settings);
 
-        _services.AddSingleton(Substitute.For<IConnectionMultiplexer>());
-        _services.TryAddExtendedCacheServices(settings);
         using var provider = _services.BuildServiceProvider();
-
+        Assert.Throws<RedisConnectionException>(() =>
-        var fusionCache = provider.GetRequiredService<IFusionCache>();
+        {
-        Assert.True(fusionCache.HasDistributedCache);
+            var cache = provider.GetRequiredKeyedService<IFusionCache>(_cacheName);
-        Assert.True(fusionCache.HasBackplane);
+            // Trigger lazy initialization
+            cache.GetOrDefault<string>("test");
+        });
     }
 
     [Fact]
-    public void TryAddFusionCoreServices_WithExistingRedis_EnablesDistributedCacheAndBackplane()
+    public void AddExtendedCache_WithExistingRedis_UsesExistingDistributedCacheAndBackplane()
     {
-        var settings = CreateGlobalSettings(new Dictionary<string, string?>
+        var settings = CreateGlobalSettings(new()
         {
             { "GlobalSettings:DistributedCache:Redis:ConnectionString", "localhost:6379" },
         });
 
         _services.AddSingleton(Substitute.For<IConnectionMultiplexer>());
         _services.AddSingleton(Substitute.For<IDistributedCache>());
-        _services.TryAddExtendedCacheServices(settings);
-        using var provider = _services.BuildServiceProvider();
 
-        var fusionCache = provider.GetRequiredService<IFusionCache>();
+        _services.AddExtendedCache(_cacheName, settings);
-        Assert.True(fusionCache.HasDistributedCache);
+
-        Assert.True(fusionCache.HasBackplane);
+        using var provider = _services.BuildServiceProvider();
-        var distributedCache = provider.GetRequiredService<IDistributedCache>();
+        var cache = provider.GetRequiredKeyedService<IFusionCache>(_cacheName);
-        Assert.NotNull(distributedCache);
+
+        Assert.True(cache.HasDistributedCache);
+        Assert.True(cache.HasBackplane);
+
+        var existingCache = provider.GetRequiredService<IDistributedCache>();
+        Assert.NotNull(existingCache);
     }
 
     [Fact]
-    public void TryAddFusionCoreServices_WithoutRedis_DisablesDistributedCacheAndBackplane()
+    public void AddExtendedCache_NoRedis_DisablesDistributedCacheAndBackplane()
     {
-        _services.TryAddExtendedCacheServices(_globalSettings);
+        _services.AddExtendedCache(_cacheName, _globalSettings);
-        using var provider = _services.BuildServiceProvider();
 
-        var fusionCache = provider.GetRequiredService<IFusionCache>();
+        using var provider = _services.BuildServiceProvider();
-        Assert.False(fusionCache.HasDistributedCache);
+        var cache = provider.GetRequiredKeyedService<IFusionCache>(_cacheName);
-        Assert.False(fusionCache.HasBackplane);
+
+        Assert.False(cache.HasDistributedCache);
+        Assert.False(cache.HasBackplane);
+    }
+
+    [Fact]
+    public void AddExtendedCache_NoSharedRedisButNoConnectionString_DisablesDistributedCacheAndBackplane()
+    {
+        var settings = new GlobalSettings.ExtendedCacheSettings
+        {
+            UseSharedRedisCache = false,
+            // No Redis connection string
+        };
+
+        _services.AddExtendedCache(_cacheName, _globalSettings, settings);
+
+        using var provider = _services.BuildServiceProvider();
+        var cache = provider.GetRequiredKeyedService<IFusionCache>(_cacheName);
+
+        Assert.False(cache.HasDistributedCache);
+        Assert.False(cache.HasBackplane);
+    }
+
+    [Fact]
+    public void AddExtendedCache_KeyedRedis_UsesSeparateMultiplexers()
+    {
+        var settingsA = new GlobalSettings.ExtendedCacheSettings
+        {
+            EnableDistributedCache = true,
+            UseSharedRedisCache = false,
+            Redis = new GlobalSettings.ConnectionStringSettings { ConnectionString = "localhost:6379" }
+        };
+        var settingsB = new GlobalSettings.ExtendedCacheSettings
+        {
+            EnableDistributedCache = true,
+            UseSharedRedisCache = false,
+            Redis = new GlobalSettings.ConnectionStringSettings { ConnectionString = "localhost:6380" }
+        };
+
+        _services.AddKeyedSingleton("CacheA", Substitute.For<IConnectionMultiplexer>());
+        _services.AddKeyedSingleton("CacheB", Substitute.For<IConnectionMultiplexer>());
+
+        _services.AddExtendedCache("CacheA", _globalSettings, settingsA);
+        _services.AddExtendedCache("CacheB", _globalSettings, settingsB);
+
+        using var provider = _services.BuildServiceProvider();
+        var muxA = provider.GetRequiredKeyedService<IConnectionMultiplexer>("CacheA");
+        var muxB = provider.GetRequiredKeyedService<IConnectionMultiplexer>("CacheB");
+
+        Assert.NotNull(muxA);
+        Assert.NotNull(muxB);
+        Assert.NotSame(muxA, muxB);
+    }
+
+    [Fact]
+    public void AddExtendedCache_WithExistingKeyedDistributedCache_ReusesIt()
+    {
+        var existingCache = Substitute.For<IDistributedCache>();
+        _services.AddKeyedSingleton<IDistributedCache>(_cacheName, existingCache);
+
+        var settings = new GlobalSettings.ExtendedCacheSettings
+        {
+            UseSharedRedisCache = false,
+            Redis = new GlobalSettings.ConnectionStringSettings { ConnectionString = "localhost:6379" }
+        };
+
+        _services.AddExtendedCache(_cacheName, _globalSettings, settings);
+
+        using var provider = _services.BuildServiceProvider();
+        var resolved = provider.GetRequiredKeyedService<IDistributedCache>(_cacheName);
+
+        Assert.Same(existingCache, resolved);
     }
 
     private static GlobalSettings CreateGlobalSettings(Dictionary<string, string?> data)