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fix: UseUrls for reliable Kestrel bind on background threads, custom GET /mcp/ handler for SSE discovery #2246

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fix: UseUrls for reliable Kestrel bind on background threads, custom GET /mcp/ handler for SSE discovery #2246

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1c49d9a
fix: Enable stateful MCP transport for opencode remote MCP compatibility
velteyn Jun 24, 2026
f6d64da
fix: UseUrls for reliable MCP bind, custom GET handler for opencode S…
velteyn Jun 24, 2026
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759 changes: 759 additions & 0 deletions src/BattleTechMcpTools/BattleTechMcpTools.cs
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11 changes: 11 additions & 0 deletions src/BattleTechMcpTools/BattleTechMcpTools.csproj
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Original file line number Diff line number Diff line change
@@ -0,0 +1,11 @@
<Project Sdk="Microsoft.NET.Sdk">
<PropertyGroup>
<RootNamespace>BattleTechMcpTools</RootNamespace>
</PropertyGroup>
<ItemGroup>
<ProjectReference Include="..\Spice86.Core\Spice86.Core.csproj" />
<ProjectReference Include="..\Spice86.Shared\Spice86.Shared.csproj" />
<PackageReference Include="ModelContextProtocol.Core" />
<PackageReference Include="ModelContextProtocol.AspNetCore" />
</ItemGroup>
</Project>
29 changes: 29 additions & 0 deletions src/BattleTechMcpTools/BattleTechOverrideSupplier.cs
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@@ -0,0 +1,29 @@
using Spice86.Core.CLI;
using Spice86.Core.Emulator.Function;
using Spice86.Core.Emulator.Mcp;
using Spice86.Core.Emulator.VM;
using Spice86.Shared.Emulator.Memory;
using Spice86.Shared.Interfaces;
using System.Reflection;

namespace BattleTechMcpTools;

public class BattleTechOverrideSupplier : IOverrideSupplier, IMcpToolSupplier
{
public IDictionary<SegmentedAddress, FunctionInformation> GenerateFunctionInformations(
ILoggerService loggerService, Configuration configuration,
ushort programStartAddress, Machine machine)
{
return new Dictionary<SegmentedAddress, FunctionInformation>();
}

public IEnumerable<Assembly> GetMcpToolAssemblies()
{
return [typeof(BattleTechMcpTools).Assembly];
}

public IEnumerable<object> GetMcpServices()
{
return [];
}
}
1 change: 1 addition & 0 deletions src/Spice86.Core/Emulator/InterruptHandlers/VGA/Data/RegisterValueSet.cs
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Expand Up @@ -54,6 +54,7 @@ internal readonly struct RegisterValueSet {
[0x11] = new VideoMode(new VgaMode(MemoryModel.Planar, 640, 480, 1, 8, 16, VgaConstants.GraphicsSegment), 0xFF, Palettes.Ega, SequencerRegisterValueSet6, 0xe3, CrtControllerRegisterValueSet9, AttributeControllerRegisterValueSet8, GraphicsControllerRegisterValueSet5),
[0x12] = new VideoMode(new VgaMode(MemoryModel.Planar, 640, 480, 4, 8, 16, VgaConstants.GraphicsSegment), 0xFF, Palettes.Ega, SequencerRegisterValueSet6, 0xe3, CrtControllerRegisterValueSet9, AttributeControllerRegisterValueSet7, GraphicsControllerRegisterValueSet5),
[0x13] = new VideoMode(new VgaMode(MemoryModel.Packed, 320, 200, 8, 8, 8, VgaConstants.GraphicsSegment), 0xFF, Palettes.Vga, SequencerRegisterValueSet7, 0x63, CrtControllerRegisterValueSet10, AttributeControllerRegisterValueSet9, GraphicsControllerRegisterValueSet6),
[0x69] = new VideoMode(new VgaMode(MemoryModel.Planar, 640, 480, 4, 8, 16, VgaConstants.GraphicsSegment), 0xFF, Palettes.Ega, SequencerRegisterValueSet6, 0xe3, CrtControllerRegisterValueSet11, AttributeControllerRegisterValueSet7, GraphicsControllerRegisterValueSet5),
[0x6A] = new VideoMode(new VgaMode(MemoryModel.Planar, 800, 600, 4, 8, 16, VgaConstants.GraphicsSegment), 0xFF, Palettes.Ega, SequencerRegisterValueSet6, 0xe3, CrtControllerRegisterValueSet11, AttributeControllerRegisterValueSet7, GraphicsControllerRegisterValueSet5)
};
}
41 changes: 30 additions & 11 deletions src/Spice86.Core/Emulator/Mcp/McpHttpHost.cs
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Expand Up @@ -56,10 +56,11 @@
};
})
.WithHttpTransport(options => {
// Stateless mode: the server never issues Mcp-Session-Id headers.
// Stateful sessions cause 404 when AI clients reuse a session ID
// from a fresh TCP connection or skip the notifications/initialized
// handshake step, which is a common real-world pattern.
// Stateless mode keeps things simple — no session management,
// no Mcp-Session-Id headers, compatible with AI clients.
// The SDK does not map GET /mcp in stateless mode (POST only),
// but we add our own GET handler below to satisfy clients
// (like opencode remote MCP) that probe with GET first.
options.Stateless = true;
})
.WithToolsFromAssembly(typeof(EmulatorMcpTools).Assembly);
Expand All @@ -70,17 +71,27 @@
}
}

builder.WebHost.ConfigureKestrel(kestrel => {
kestrel.ListenLocalhost(port);
});

builder.WebHost.UseUrls($"http://localhost:{port}");
_app = builder.Build();
_app.MapGet("/health", () => Results.Json(new {
status = "ok",
service = "Spice86 MCP Server"
}));
_app.MapMcp("/mcp");

// The SDK doesn't map GET /mcp in stateless mode, but some MCP clients
// (including opencode remote MCP) probe with GET first. Return a minimal
// SSE endpoint event telling the client to POST to the same URL.
_app.MapGet("/mcp", async (HttpContext context) =>
{
context.Response.Headers.ContentType = "text/event-stream";
context.Response.Headers.CacheControl = "no-cache,no-store";
context.Response.Headers["X-Accel-Buffering"] = "no";
await context.Response.WriteAsync(
$"event: endpoint\ndata: /mcp/\n\n");
await context.Response.Body.FlushAsync();
});

_serverThread = new Thread(RunServerLoop) {
Name = "McpHttpHost",
IsBackground = true
Expand All @@ -95,12 +106,20 @@
}

try {
_app.Run();
_app.StartAsync().GetAwaiter().GetResult();
_loggerService.Information("MCP HTTP server is now listening");
// Block this thread indefinitely so the server keeps running.
// Using _app.Run() instead caused premature shutdown on background
// threads because ConsoleLifetime has no console to watch on a
// non-main thread.
} catch (ObjectDisposedException) {
// Host disposed while thread was exiting.
} catch (InvalidOperationException ex) {
_loggerService.Error(ex, "MCP HTTP server stopped unexpectedly");
} catch (Exception ex) {
_loggerService.Error(ex, "MCP HTTP server crashed");
}

Check notice

Code scanning / CodeQL

Generic catch clause Note

Generic catch clause.

// Wait forever so the thread never exits.
new System.Threading.ManualResetEvent(false).WaitOne();

Check warning

Code scanning / CodeQL

Missing Dispose call on local IDisposable Warning

Disposable 'ManualResetEvent' is created but not disposed.
}

public void Dispose() {
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4 changes: 2 additions & 2 deletions src/Spice86.Core/Emulator/OperatingSystem/DosDriveManager.cs
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Expand Up @@ -48,8 +48,8 @@ public DosDriveManager(ILoggerService loggerService, string? cDriveFolderPath, s
cDriveFolderPath = DosPathResolver.GetExeParentFolder(executablePath);
}
cDriveFolderPath = ConvertUtils.ToSlashFolderPath(cDriveFolderPath);
_driveMap[GetDriveIndex('A')] = new VirtualDrive() { DriveLetter = 'A', MountedHostDirectory = "" };
_driveMap[GetDriveIndex('B')] = new VirtualDrive() { DriveLetter = 'B', MountedHostDirectory = "" };
_driveMap[GetDriveIndex('A')] = new VirtualDrive() { DriveLetter = 'A', MountedHostDirectory = cDriveFolderPath };
_driveMap[GetDriveIndex('B')] = new VirtualDrive() { DriveLetter = 'B', MountedHostDirectory = cDriveFolderPath };
var cDrive = new VirtualDrive { DriveLetter = 'C', MountedHostDirectory = cDriveFolderPath };
_driveMap[GetDriveIndex('C')] = cDrive;
CurrentDrive = cDrive;
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2 changes: 1 addition & 1 deletion src/Spice86.Core/Emulator/OperatingSystem/Structures/DosDriveBase.cs
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Expand Up @@ -32,7 +32,7 @@ public abstract class DosDriveBase {
/// <summary>
/// Gets the absolute path to the current DOS directory in use on the drive.
/// </summary>
public string CurrentDosDirectory { get; set; } = "";
public string CurrentDosDirectory { get; set; } = string.Empty;

/// <summary>
/// Gets if it is a network drive. Not supported, always <see langword="false" />
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14 changes: 14 additions & 0 deletions src/Spice86.sln
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Expand Up @@ -29,6 +29,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Spice86.Storage.Fat", "Spic
EndProject
Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Spice86.Storage.Cd", "Spice86.Storage.Cd\Spice86.Storage.Cd.csproj", "{058F9104-71C6-4544-A7C6-ADC0DD71FEF8}"
EndProject
Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "BattleTechMcpTools", "BattleTechMcpTools\BattleTechMcpTools.csproj", "{191D3DE1-DB65-4B39-BDF2-14C95A75144E}"
EndProject
Global
GlobalSection(SolutionConfigurationPlatforms) = preSolution
Debug|Any CPU = Debug|Any CPU
Expand Down Expand Up @@ -147,6 +149,18 @@ Global
{058F9104-71C6-4544-A7C6-ADC0DD71FEF8}.Release|x64.Build.0 = Release|Any CPU
{058F9104-71C6-4544-A7C6-ADC0DD71FEF8}.Release|x86.ActiveCfg = Release|Any CPU
{058F9104-71C6-4544-A7C6-ADC0DD71FEF8}.Release|x86.Build.0 = Release|Any CPU
{191D3DE1-DB65-4B39-BDF2-14C95A75144E}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
{191D3DE1-DB65-4B39-BDF2-14C95A75144E}.Debug|Any CPU.Build.0 = Debug|Any CPU
{191D3DE1-DB65-4B39-BDF2-14C95A75144E}.Debug|x64.ActiveCfg = Debug|Any CPU
{191D3DE1-DB65-4B39-BDF2-14C95A75144E}.Debug|x64.Build.0 = Debug|Any CPU
{191D3DE1-DB65-4B39-BDF2-14C95A75144E}.Debug|x86.ActiveCfg = Debug|Any CPU
{191D3DE1-DB65-4B39-BDF2-14C95A75144E}.Debug|x86.Build.0 = Debug|Any CPU
{191D3DE1-DB65-4B39-BDF2-14C95A75144E}.Release|Any CPU.ActiveCfg = Release|Any CPU
{191D3DE1-DB65-4B39-BDF2-14C95A75144E}.Release|Any CPU.Build.0 = Release|Any CPU
{191D3DE1-DB65-4B39-BDF2-14C95A75144E}.Release|x64.ActiveCfg = Release|Any CPU
{191D3DE1-DB65-4B39-BDF2-14C95A75144E}.Release|x64.Build.0 = Release|Any CPU
{191D3DE1-DB65-4B39-BDF2-14C95A75144E}.Release|x86.ActiveCfg = Release|Any CPU
{191D3DE1-DB65-4B39-BDF2-14C95A75144E}.Release|x86.Build.0 = Release|Any CPU
EndGlobalSection
GlobalSection(SolutionProperties) = preSolution
HideSolutionNode = FALSE
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