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Fix/websocket queue to main thread #443

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Merged
dsarno merged 3 commits into from
Dec 8, 2025
Merged

Fix/websocket queue to main thread #443

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208cbf4
feat: Implement async method to retrieve enabled tools on the main th…
Jordonh18 Dec 8, 2025
1a900a7
fix: cancelable main-thread tool discovery
dsarno Dec 8, 2025
383c0c1
chore: dispose cancellation registration and dedupe usings
dsarno Dec 8, 2025
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37 changes: 36 additions & 1 deletion MCPForUnity/Editor/Services/Transport/Transports/WebSocketTransportClient.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -8,9 +8,11 @@
using System.Threading.Tasks;
using MCPForUnity.Editor.Config;
using MCPForUnity.Editor.Helpers;
using MCPForUnity.Editor.Services;
using MCPForUnity.Editor.Services.Transport;
using Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using UnityEditor;
using UnityEngine;

namespace MCPForUnity.Editor.Services.Transport.Transports
Expand Down Expand Up @@ -65,6 +67,37 @@ public WebSocketTransportClient(IToolDiscoveryService toolDiscoveryService = nul
public string TransportName => TransportDisplayName;
public TransportState State => _state;

private Task<List<ToolMetadata>> GetEnabledToolsOnMainThreadAsync(CancellationToken token)
{
var tcs = new TaskCompletionSource<List<ToolMetadata>>(TaskCreationOptions.RunContinuationsAsynchronously);

// Register cancellation to break the deadlock if StopAsync is called while waiting for main thread
var registration = token.Register(() => tcs.TrySetCanceled());

EditorApplication.delayCall += () =>
{
try
{
// Clean up the registration once we're running
registration.Dispose();

if (tcs.Task.IsCompleted)
{
return;
}

var tools = _toolDiscoveryService?.GetEnabledTools() ?? new List<ToolMetadata>();
tcs.TrySetResult(tools);
}
catch (Exception ex)
{
tcs.TrySetException(ex);
}
};

return tcs.Task;
}

public async Task<bool> StartAsync()
{
// Capture identity values on the main thread before any async context switching
Expand Down Expand Up @@ -421,7 +454,9 @@ private async Task SendRegisterToolsAsync(CancellationToken token)
{
if (_toolDiscoveryService == null) return;

var tools = _toolDiscoveryService.GetEnabledTools();
token.ThrowIfCancellationRequested();
var tools = await GetEnabledToolsOnMainThreadAsync(token).ConfigureAwait(false);
token.ThrowIfCancellationRequested();
McpLog.Info($"[WebSocket] Preparing to register {tools.Count} tool(s) with the bridge.");
var toolsArray = new JArray();

Expand Down