Add UseChatClients for configuration-driven clients

Author: kzu

src/AI.Tests/ConfigurableTests.cs

@@ -0,0 +1,37 @@
+using System.Threading.Tasks;
+using Microsoft.Extensions.AI;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Devlooped.Extensions.AI;
+
+public class ConfigurableTests
+{
+    [Fact]
+    public async Task CanConfigureClients()
+    {
+        var configuration = new ConfigurationBuilder()
+            .AddInMemoryCollection(new Dictionary<string, string?>
+            {
+                ["ai:clients:openai:modelid"] = "gpt-4.1.nano",
+                ["ai:clients:openai:ApiKey"] = "sk-asdfasdf",
+                ["ai:clients:grok:modelid"] = "grok-4-fast",
+                ["ai:clients:grok:ApiKey"] = "xai-asdfasdf",
+                ["ai:clients:grok:endpoint"] = "https://api.x.ai",
+            })
+            .Build();
+
+        var calls = new List<string>();
+
+        var services = new ServiceCollection()
+            .AddSingleton<IConfiguration>(configuration)
+            .UseChatClients(configuration)
+            .BuildServiceProvider();
+
+        var openai = services.GetRequiredKeyedService<IChatClient>("openai");
+        var grok = services.GetRequiredKeyedService<IChatClient>("grok");
+
+        Assert.Equal("openai", openai.GetRequiredService<ChatClientMetadata>().ProviderName);
+        Assert.Equal("x.ai", grok.GetRequiredService<ChatClientMetadata>().ProviderName);
+    }
+}

src/AI/AI.csproj

@@ -12,6 +12,7 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="Microsoft.Extensions.Configuration.Binder" Version="9.0.9" />
     <PackageReference Include="NuGetizer" Version="1.3.1" PrivateAssets="all" />
     <PackageReference Include="Microsoft.Extensions.AI" Version="9.9.1" />
     <PackageReference Include="Microsoft.Extensions.AI.OpenAI" Version="9.8.0-preview.1.25412.6" />

src/AI/UseChatClientsExtensions.cs

@@ -0,0 +1,64 @@
+using Devlooped.Extensions.AI.Grok;
+using Devlooped.Extensions.AI.OpenAI;
+using Microsoft.Extensions.AI;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using OpenAI;
+
+namespace Devlooped.Extensions.AI;
+
+public static class UseChatClientsExtensions
+{
+    public static IServiceCollection UseChatClients(this IServiceCollection services, IConfiguration configuration, Action<string, ChatClientBuilder>? configure = default, string prefix = "ai:clients")
+    {
+        foreach (var entry in configuration.AsEnumerable().Where(x =>
+            x.Key.StartsWith(prefix, StringComparison.OrdinalIgnoreCase) &&
+            x.Key.EndsWith("modelid", StringComparison.OrdinalIgnoreCase)))
+        {
+            var section = string.Join(':', entry.Key.Split(':')[..^1]);
+            // ID == section after clients:, with optional overridable id
+            var id = configuration[$"{section}:id"] ?? section[(prefix.Length + 1)..];
+                
+            var options = configuration.GetSection(section).Get<ChatClientOptions>();
+            Throw.IfNullOrEmpty(options?.ModelId, entry.Key);
+
+            var apikey = options!.ApiKey;
+            // If the key contains a section-like value, get it from config
+            if (apikey?.Contains('.') == true || apikey?.Contains(':') == true)
+                apikey = configuration[apikey.Replace('.', ':')] ?? configuration[apikey.Replace('.', ':') + ":apikey"];
+
+            var keysection = section;
+            // ApiKey inheritance by section parents. 
+            // i.e. section ai:clients:grok:router does not need to have its own key, 
+            // it will inherit from ai:clients:grok:key, for example.
+            while (string.IsNullOrEmpty(apikey))
+            {
+                keysection = string.Join(':', keysection.Split(':')[..^1]);
+                if (string.IsNullOrEmpty(keysection))
+                    break;
+                apikey = configuration[$"{keysection}:apikey"];
+            }
+
+            Throw.IfNullOrEmpty(apikey, $"{section}:apikey");
+
+            var builder = services.AddKeyedChatClient(id, services =>
+            {
+                if (options.Endpoint?.Host == "api.x.ai")
+                    return new GrokChatClient(apikey, options.ModelId, options);
+
+                return new OpenAIChatClient(apikey, options.ModelId, options);
+            }, options.Lifetime);
+
+            configure?.Invoke(id, builder);
+        }
+
+        return services;
+    }
+
+    class ChatClientOptions : OpenAIClientOptions
+    {
+        public string? ApiKey { get; set; }
+        public string? ModelId { get; set; }
+        public ServiceLifetime Lifetime { get; set; } = ServiceLifetime.Singleton;
+    }
+}