feat(telegram): serve A2A from the bot, callers per chat workspace, notify_owner into the chat

hosts/Volcanic.AgenticCore.Telegram/A2A/NoHttpServer.cs

@@ -0,0 +1,13 @@
+using Microsoft.AspNetCore.Hosting.Server;
+using Microsoft.AspNetCore.Http.Features;
+
+namespace Volcanic.AgenticCore.Telegram.A2A;
+
+/// <summary>Replaces Kestrel when A2A is off, so the bot opens no port.</summary>
+internal sealed class NoHttpServer : IServer
+{
+    public IFeatureCollection Features { get; } = new FeatureCollection();
+    public Task StartAsync<TContext>(IHttpApplication<TContext> application, CancellationToken cancellationToken) where TContext : notnull => Task.CompletedTask;
+    public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;
+    public void Dispose() { }
+}

hosts/Volcanic.AgenticCore.Telegram/A2A/TelegramA2ASetup.cs

@@ -0,0 +1,55 @@
+using System.Globalization;
+using Microsoft.AspNetCore.Hosting.Server;
+using Microsoft.AspNetCore.Routing;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
+using Volcanic.AgenticCore.A2A.Server;
+using Volcanic.AgenticCore.A2A.Server.Callers;
+using Volcanic.AgenticCore.A2A.Server.Hosting;
+using Volcanic.AgenticCore.Telegram.Chats;
+
+namespace Volcanic.AgenticCore.Telegram.A2A;
+
+/// <summary>Serves A2A from the bot: callers live in the allowed chats' workspaces, <c>notify_owner</c> goes to the chat.</summary>
+public static class TelegramA2ASetup
+{
+    /// <summary>Allowed chats' workspaces: only they can hold callers.</summary>
+    public static Func<IEnumerable<A2AWorkspace>> Workspaces(TelegramOptions options) => () =>
+        options.AllowedUserIds.Select(id => new A2AWorkspace(
+            ChatRegistry.WorkspaceFor(options, id), ChatRegistry.ScopeFor(id), id.ToString(CultureInfo.InvariantCulture)));
+
+    public static void Register(IServiceCollection services, TelegramOptions options, A2AHostOptions a2a)
+    {
+        services.AddSingleton(a2a);
+        if (!a2a.Enabled)
+        {
+            services.AddSingleton<IServer, NoHttpServer>();
+            return;
+        }
+        services.AddSingleton<IA2ACallerDirectory>(sp => new WorkspaceCallerDirectory(Workspaces(options), sp.GetRequiredService<ILogger<WorkspaceCallerDirectory>>()));
+        services.AddSingleton<IA2AOwnerNotifier>(sp => new TelegramOwnerNotifier(() => sp.GetRequiredService<ChatRegistry>()));
+        services.AddA2AServer(o =>
+        {
+            o.Enabled = true;
+            o.PublicUrl = a2a.PublicUrl;
+            o.MaxHops = a2a.MaxHops;
+            o.SessionIdleTimeout = a2a.SessionIdleTimeout;
+            o.MaxFileBytes = a2a.MaxFileBytes;
+            o.AllowPrivatePushUrls = a2a.AllowPrivatePushUrls;
+            o.Card = a2a.Card;
+            o.Model = options.Model;
+            o.OnPush = a2a.OnPush;
+        });
+        // Each session's zone is its owner's chat setting (read when the session opens).
+        services.AddOptions<A2AHostOptions>().Configure<IServiceProvider>((o, sp) =>
+            o.TimeZoneFor = caller => sp.GetService<ChatSettingsStore>()?.TimeZoneFor(long.Parse(caller.OwnerId, CultureInfo.InvariantCulture)));
+    }
+
+    public static void Map(IEndpointRouteBuilder app, A2AHostOptions a2a)
+    {
+        if (a2a.Enabled) app.MapA2AServer();
+    }
+
+    public static string Describe(A2AHostOptions a2a) =>
+        a2a.Enabled ? $"A2A: on at {a2a.PublicUrl ?? "(request host)"}/a2a, callers in each chat's .volcanic/a2a/callers.json" : "A2A: off";
+}

hosts/Volcanic.AgenticCore.Telegram/A2A/TelegramOwnerNotifier.cs

@@ -0,0 +1,16 @@
+using System.Globalization;
+using Volcanic.AgenticCore.A2A.Server.Callers;
+using Volcanic.AgenticCore.Telegram.Chats;
+
+namespace Volcanic.AgenticCore.Telegram.A2A;
+
+/// <summary><c>notify_owner</c> → "🤖 A2A · caller: text" in the owner's chat, through its chat channel (in order with output).</summary>
+internal sealed class TelegramOwnerNotifier(Func<ChatRegistry> chats) : IA2AOwnerNotifier
+{
+    public async Task NotifyAsync(A2ACaller caller, string text, CancellationToken cancellationToken)
+    {
+        var chatId = long.Parse(caller.OwnerId, CultureInfo.InvariantCulture);
+        var chat = await chats().GetAsync(chatId, cancellationToken).ConfigureAwait(false);
+        await chat.Channel.SendTextAsync($"🤖 A2A · {caller.Name}: {text}", cancellationToken).ConfigureAwait(false);
+    }
+}

hosts/Volcanic.AgenticCore.Telegram/Program.cs

@@ -3,6 +3,7 @@
 //
 //   TELEGRAM_BOT_TOKEN=123:abc TELEGRAM_ALLOWED_USER_IDS=111111 dotnet run --project hosts/Volcanic.AgenticCore.Telegram
 
+using Microsoft.AspNetCore.Builder;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.DependencyInjection.Extensions;
@@ -10,12 +11,14 @@ using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Telegram.Bot;
+using Volcanic.AgenticCore.A2A.Server;
 using Volcanic.AgenticCore.Extensions.ClaudeCode;
 using Volcanic.AgenticCore.Extensions.Mcp;
 using Volcanic.AgenticCore.Extensions.Scheduler;
 using Volcanic.AgenticCore.Features.Processes;
 using Volcanic.AgenticCore.Hosting;
 using Volcanic.AgenticCore.Telegram;
+using Volcanic.AgenticCore.Telegram.A2A;
 using Volcanic.AgenticCore.Telegram.Chats;
 using Volcanic.AgenticCore.Telegram.Inbound;
 using Volcanic.AgenticCore.Telegram.Polling;
@@ -24,7 +27,7 @@ using Volcanic.AgenticCore.Telegram.Scheduling;
 using Volcanic.AgenticCore.Telegram.Speech;
 using Volcanic.AgenticCore.Telegram.Triggers;
 
-var builder = Host.CreateApplicationBuilder(args);
+var builder = WebApplication.CreateBuilder(args);
 
 var options = builder.Configuration.GetSection(TelegramOptions.SectionName).Get<TelegramOptions>() ?? new TelegramOptions();
 options.ApplyEnvironment(Environment.GetEnvironmentVariable);
@@ -36,6 +39,8 @@ var processEnvironment = new ProcessEnvironmentOptions();
 TelegramProcessEnvironment.Configure(processEnvironment, options, processSection, Environment.GetEnvironmentVariable, calendar);
 var mcp = builder.Configuration.GetSection(McpOptions.SectionName).Get<McpOptions>() ?? new McpOptions();
 mcp.ApplyEnvironment(Environment.GetEnvironmentVariable);
+// Off: no HTTP listener at all (NoHttpServer replaces Kestrel). On: the A2A endpoints on Kestrel (ASPNETCORE_URLS / Urls).
+var a2a = builder.Configuration.GetSection(A2AHostOptions.SectionName).Get<A2AHostOptions>() ?? new A2AHostOptions();
 // One agent directory for sessions, chat-settings.json and scheduler/jobs.json.
 var agentDir = VolcanicPaths.DefaultAgentDir;
 var scheduling = SchedulerSetup.Options(builder.Configuration.GetSection(SchedulerOptions.SectionName), agentDir);
@@ -102,8 +107,10 @@ if (options.Triggers.IsEnabled) TriggersSetup.Register(builder.Services, options
 // Watchers get a short-lived GOOGLE_ACCESS_TOKEN for their chat's calendar, never the client secret or refresh token.
 if (scheduling.Enabled && calendar is not null) builder.Services.AddSingleton<IScriptEnvironment, CalendarScriptEnvironment>();
 builder.Services.AddHostedService<BotSetupService>();
+TelegramA2ASetup.Register(builder.Services, options, a2a);
 
-using var host = builder.Build();
+await using var host = builder.Build();
+TelegramA2ASetup.Map(host, a2a);
 
 var logger = host.Services.GetRequiredService<ILoggerFactory>().CreateLogger("Volcanic.AgenticCore.Telegram");
 // Before polling and the first claude process; the spawn policy's own call later is a no-op.
@@ -112,6 +119,7 @@ logger.LogInformation("{ProcessEnvironment}", TelegramProcessEnvironment.Describ
 logger.LogInformation("{Mcp}", mcp.DescribePlaywright());
 logger.LogInformation("{Speech}", options.Speech.Describe());
 logger.LogInformation("{Triggers}", options.Triggers.Describe());
+logger.LogInformation("{A2A}", TelegramA2ASetup.Describe(a2a));
 if (ClaudeInstallation.Locate(Environment.GetEnvironmentVariable) is { } claude)
     logger.LogInformation("Using Claude Code at {Path}, model {Model}", claude, options.Model);
 else

hosts/Volcanic.AgenticCore.Telegram/Volcanic.AgenticCore.Telegram.csproj

@@ -4,13 +4,13 @@
     <UserSecretsId>volcanic-agentic-core-telegram</UserSecretsId>
   </PropertyGroup>
   <ItemGroup>
+    <FrameworkReference Include="Microsoft.AspNetCore.App" />
     <ProjectReference Include="../../src/Volcanic.AgenticCore/Volcanic.AgenticCore.csproj" />
+    <ProjectReference Include="../../src/Volcanic.AgenticCore.A2A.Server/Volcanic.AgenticCore.A2A.Server.csproj" />
     <ProjectReference Include="../../extensions/Volcanic.AgenticCore.Extensions.ClaudeCode/Volcanic.AgenticCore.Extensions.ClaudeCode.csproj" />
     <ProjectReference Include="../../extensions/Volcanic.AgenticCore.Extensions.GoogleCalendar/Volcanic.AgenticCore.Extensions.GoogleCalendar.csproj" />
     <ProjectReference Include="../../extensions/Volcanic.AgenticCore.Extensions.Mcp/Volcanic.AgenticCore.Extensions.Mcp.csproj" />
     <ProjectReference Include="../../extensions/Volcanic.AgenticCore.Extensions.Scheduler/Volcanic.AgenticCore.Extensions.Scheduler.csproj" />
-    <PackageReference Include="Microsoft.Extensions.Hosting" Version="10.0.0" />
-    <PackageReference Include="Microsoft.Extensions.Http" Version="10.0.0" />
     <PackageReference Include="Telegram.Bot" Version="22.10.3.1" />
   </ItemGroup>
   <ItemGroup>

hosts/Volcanic.AgenticCore.Telegram/appsettings.json

@@ -10,5 +10,6 @@
     "BotToken": "",
     "AllowedUserIds": [],
     "Model": "claude-code/claude-opus-5-5"
-  }
+  },
+  "A2A": { "Enabled": false, "PublicUrl": null, "MaxHops": 3, "SessionIdleTimeout": "00:30:00", "MaxFileBytes": 10485760, "AllowPrivatePushUrls": false }
 }

tests/Volcanic.AgenticCore.Telegram.Tests/A2AHostTests.cs

@@ -0,0 +1,53 @@
+using Microsoft.AspNetCore.Hosting.Server;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging.Abstractions;
+using Volcanic.AgenticCore.A2A.Server;
+using Volcanic.AgenticCore.A2A.Server.Callers;
+using Volcanic.AgenticCore.Telegram.A2A;
+using Volcanic.AgenticCore.Telegram.Tests.Support;
+
+namespace Volcanic.AgenticCore.Telegram.Tests;
+
+public class A2AHostTests
+{
+    private static void WriteCallers(string workspace, string json)
+    {
+        Directory.CreateDirectory(Path.GetDirectoryName(CallersFile.PathFor(workspace))!);
+        File.WriteAllText(CallersFile.PathFor(workspace), json);
+    }
+
+    [Fact]
+    public async Task CallerDirectory_OnlyAllowedChats_LiveEdit()
+    {
+        await using var host = new ChatHost();
+        var directory = new WorkspaceCallerDirectory(TelegramA2ASetup.Workspaces(host.Options), NullLogger<WorkspaceCallerDirectory>.Instance);
+        var allowed = host.WorkspaceOf(Updates.AllowedUser);
+        var stranger = Path.Combine(host.Options.WorkspaceRoot, "999");
+        WriteCallers(stranger, """[ { "name": "x", "key": "k-stranger" } ]""");
+        Assert.Empty(directory.Find("k-stranger"));
+        Assert.Empty(directory.Find("k1"));
+        WriteCallers(allowed, """[ { "name": "travel-bot", "key": "k1" } ]""");
+        var caller = Assert.Single(directory.Find("k1"));
+        Assert.Equal($"telegram-{Updates.AllowedUser}", caller.ScopePrefix);
+        Assert.Equal(Updates.AllowedUser.ToString(), caller.OwnerId);
+    }
+
+    [Fact]
+    public async Task NotifyOwner_ReachesOwnersChat()
+    {
+        await using var host = new ChatHost();
+        var notifier = new TelegramOwnerNotifier(() => host.Chats);
+        var caller = new A2ACaller("travel-bot", "isolated", host.WorkspaceOf(), "telegram-1001", Updates.AllowedUser.ToString());
+        await notifier.NotifyAsync(caller, "Alice booked Friday", CancellationToken.None);
+        Assert.Contains(host.Texts, t => t.Contains("A2A · travel-bot: Alice booked Friday"));
+    }
+
+    [Fact]
+    public void A2aDisabled_NoEndpoints()
+    {
+        var services = new ServiceCollection();
+        TelegramA2ASetup.Register(services, new TelegramOptions { BotToken = "t", AllowedUserIds = [1] }, new A2AHostOptions { Enabled = false });
+        Assert.Contains(services, d => d.ServiceType == typeof(IServer) && d.ImplementationType == typeof(NoHttpServer));
+        Assert.DoesNotContain(services, d => d.ServiceType == typeof(IA2ACallerDirectory));
+    }
+}

tests/Volcanic.AgenticCore.Telegram.Tests/Volcanic.AgenticCore.Telegram.Tests.csproj

@@ -11,6 +11,7 @@
     <PackageReference Include="Microsoft.Extensions.TimeProvider.Testing" Version="10.9.0" />
   </ItemGroup>
   <ItemGroup>
+    <FrameworkReference Include="Microsoft.AspNetCore.App" />
     <ProjectReference Include="../../hosts/Volcanic.AgenticCore.Telegram/Volcanic.AgenticCore.Telegram.csproj" />
   </ItemGroup>
   <ItemGroup>