Add support for configurable and composable AI contexts

src/Agents/CompositeAIContextProvider.cs

@@ -0,0 +1,52 @@
+using Microsoft.Agents.AI;
+using Microsoft.Extensions.AI;
+
+namespace Devlooped.Agents.AI;
+
+/// <summary>
+/// Concatenates multiple <see cref="AIContext"/> instances into a single one.
+/// </summary>
+class CompositeAIContextProvider : AIContextProvider
+{
+    readonly AIContext context;
+
+    public CompositeAIContextProvider(IList<AIContext> contexts)
+    {
+        if (contexts.Count == 1)
+        {
+            context = contexts[0];
+            return;
+        }
+
+        // Concatenate instructions from all contexts
+        context = new();
+        var instructions = new List<string>();
+        var messages = new List<ChatMessage>();
+        var tools = new List<AITool>();
+
+        foreach (var ctx in contexts)
+        {
+            if (!string.IsNullOrEmpty(ctx.Instructions))
+                instructions.Add(ctx.Instructions);
+
+            if (ctx.Messages != null)
+                messages.AddRange(ctx.Messages);
+
+            if (ctx.Tools != null)
+                tools.AddRange(ctx.Tools);
+        }
+
+        // Same separator used by M.A.AI for instructions appending from AIContext
+        if (instructions.Count > 0)
+            context.Instructions = string.Join('\n', instructions);
+
+        if (messages.Count > 0)
+            context.Messages = messages;
+
+        if (tools.Count > 0)
+            context.Tools = tools;
+    }
+
+    public override ValueTask<AIContext> InvokingAsync(InvokingContext context, CancellationToken cancellationToken = default)
+        => ValueTask.FromResult(this.context);
+}

src/Agents/ConfigurableAIAgent.cs

@@ -113,7 +113,45 @@ public override IAsyncEnumerable<AgentRunResponseUpdate> RunStreamingAsync(IEnum
                 services.GetService<AIContextProviderFactory>();
 
             if (contextFactory is not null)
+            {
+                if (options.Use?.Count > 0)
+                    throw new InvalidOperationException($"Invalid simultaneous use of keyed service {nameof(AIContextProviderFactory)} and '{section}:use' in configuration.");
+
                 options.AIContextProviderFactory = contextFactory.CreateProvider;
+            }
+            else if (services.GetKeyedService<AIContextProvider>(name) is { } contextProvider)
+            {
+                if (options.Use?.Count > 0)
+                    throw new InvalidOperationException($"Invalid simultaneous use of keyed service {nameof(AIContextProvider)} and '{section}:use' in configuration.");
+
+                options.AIContextProviderFactory = _ => contextProvider;
+            }
+            else if (options.Use?.Count > 0)
+            {
+                var contexts = new List<AIContext>();
+                foreach (var use in options.Use)
+                {
+                    var context = services.GetKeyedService<AIContext>(use);
+                    if (context is null)
+                    {
+                        var function = services.GetKeyedService<AITool>(use) ??
+                            services.GetKeyedService<AIFunction>(use) ??
+                            throw new InvalidOperationException($"Specified AI context '{use}' for agent '{name}' is not registered as either an {nameof(AIContent)} or an {nameof(AITool)}.");
+
+                        contexts.Add(new AIContext { Tools = [function] });
+                    }
+                    else
+                    {
+                        contexts.Add(context);
+                    }
+                }
+
+                options.AIContextProviderFactory = _ => new CompositeAIContextProvider(contexts);
+            }
+        }
+        else if (options.Use?.Count > 0)
+        {
+            throw new InvalidOperationException($"Invalid simultaneous use of {nameof(ChatClientAgentOptions)}.{nameof(ChatClientAgentOptions.AIContextProviderFactory)} and '{section}:use' in configuration.");
         }
 
         if (options.ChatMessageStoreFactory is null)
@@ -148,6 +186,7 @@ void OnReload(object? state)
     internal class AgentClientOptions : ChatClientAgentOptions
     {
         public string? Client { get; set; }
+        public IList<string>? Use { get; set; }
     }
 }