Refresh DNS in WLedClient(string) via SocketsHttpHandler

Use a SocketsHttpHandler with a 2-minute PooledConnectionLifetime for
the self-owned HttpClient on modern runtimes so a long-lived client
picks up DNS/IP changes, falling back to HttpClientHandler on
netstandard2.0. Expose CreateDefaultHandler internally for testing and
document the behaviour (fixes #8).

Author: kevbite

CHANGELOG.md

@@ -48,6 +48,11 @@ rather than deprecated, so consuming code must be updated.
 - **`ColorTemperature.Kelvin` range widened to `1000–20000 K`** to match the docs' forward-
   compatible guidance, with a new `ColorTemperature.KelvinUnchecked(int)` escape hatch for
   values outside that range.
+- **`WLedClient(string)` now refreshes DNS.** The convenience constructor's self-owned
+  `HttpClient` uses a `SocketsHttpHandler` with a bounded `PooledConnectionLifetime` (2 minutes)
+  on modern runtimes, so a long-lived client picks up DNS/IP changes instead of pinning a stale
+  connection (fixes [#8](https://github.com/kevbite/WLED.NET/issues/8)). The `netstandard2.0`
+  build falls back to `HttpClientHandler`; use `IHttpClientFactory`/DI there.
 
 ### Added
 

README.md

@@ -41,6 +41,11 @@ services.AddWledClient("http://office-computer-wled/");
 services.AddWledClient(client => client.BaseAddress = new Uri("http://office-computer-wled/"));
 ```
 
+The `WLedClient(string)` constructor owns its `HttpClient` and uses a `SocketsHttpHandler`
+with a bounded `PooledConnectionLifetime`, so a long-lived client still picks up DNS changes
+(e.g. a WLED device that gets a new IP). For applications, registering via
+`IHttpClientFactory`/DI as above remains the recommended approach.
+
 ### Quick commands
 
 Common operations have first-class "intent" methods:

src/Kevsoft.WLED/Kevsoft.WLED.csproj

@@ -22,6 +22,10 @@
     <None Include="../../icon.png" Pack="true" Visible="false" PackagePath="" />
   </ItemGroup>
 
+  <ItemGroup>
+    <InternalsVisibleTo Include="Kevsoft.WLED.Tests" />
+  </ItemGroup>
+
   <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
     <PackageReference Include="System.Net.Http.Json" Version="6.0.0" />
     <PackageReference Include="System.Text.Json" Version="8.0.5" />

src/Kevsoft.WLED/WLedClient.cs

@@ -9,7 +9,7 @@ public WLedClient(HttpMessageHandler httpMessageHandler, string baseUri)
     {
     }
 
-    public WLedClient(string baseUri) : this(new HttpClientHandler(), baseUri)
+    public WLedClient(string baseUri) : this(CreateDefaultHandler(), baseUri)
     {
     }
 
@@ -38,6 +38,25 @@ private static HttpClient CreateClient(HttpMessageHandler httpMessageHandler, st
         return client;
     }
 
+    /// <summary>
+    /// Creates the default <see cref="HttpMessageHandler"/> used when the client owns its own
+    /// <see cref="HttpClient"/>. On modern runtimes this is a <c>SocketsHttpHandler</c> with a bounded
+    /// <c>PooledConnectionLifetime</c> so pooled connections — and therefore DNS — are refreshed
+    /// periodically. See
+    /// https://learn.microsoft.com/dotnet/fundamentals/networking/http/httpclient-guidelines#dns-behavior.
+    /// </summary>
+    internal static HttpMessageHandler CreateDefaultHandler()
+    {
+#if NETSTANDARD2_0
+        return new HttpClientHandler();
+#else
+        return new SocketsHttpHandler
+        {
+            PooledConnectionLifetime = TimeSpan.FromMinutes(2)
+        };
+#endif
+    }
+
     public Task<WLedRootResponse> Get(CancellationToken cancellationToken = default)
         => GetJson<WLedRootResponse>("json", cancellationToken);
 

test/Kevsoft.WLED.Tests/WLedClientConstructionTests.cs

@@ -0,0 +1,25 @@
+using System.Net.Http;
+
+namespace Kevsoft.WLED.Tests;
+
+public class WLedClientConstructionTests
+{
+    [Fact]
+    public void StringConstructorSucceeds()
+    {
+        var act = () => new WLedClient("http://wled.local/");
+
+        act.Should().NotThrow();
+    }
+
+#if !NETSTANDARD2_0
+    [Fact]
+    public void DefaultHandlerRefreshesPooledConnectionsToAvoidStaleDns()
+    {
+        var handler = WLedClient.CreateDefaultHandler();
+
+        handler.Should().BeOfType<SocketsHttpHandler>()
+            .Which.PooledConnectionLifetime.Should().Be(TimeSpan.FromMinutes(2));
+    }
+#endif
+}