feat(engine): WebhookRegistry — (workflowId, path) → invocation lookup

src/VolcanicCore.Api/Engine/WebhookRegistry.cs

@@ -0,0 +1,36 @@
+using System.Collections.Concurrent;
+using System.Text.Json;
+
+namespace VolcanicCore.Api.Engine;
+
+public delegate Task WebhookInvocation(JsonElement body, Guid answerChannelId, CancellationToken ct);
+
+public sealed class WebhookRegistry
+{
+    private sealed record Key(string WorkflowId, string Path);
+    private readonly ConcurrentDictionary<Key, WebhookInvocation> _routes = new();
+
+    // Returns an IDisposable that removes the registration when disposed —
+    // that's what WebhookNode.StartAsync will hand back to TriggerHost.
+    public IDisposable Register(string workflowId, string path, WebhookInvocation invoke)
+    {
+        var key = new Key(workflowId, Normalize(path));
+        if (!_routes.TryAdd(key, invoke))
+            throw new InvalidOperationException(
+                $"Webhook path '{path}' is already registered for workflow {workflowId}.");
+        return new Unregister(this, key);
+    }
+
+    public WebhookInvocation? Lookup(string workflowId, string path)
+        => _routes.TryGetValue(new Key(workflowId, Normalize(path)), out var cb) ? cb : null;
+
+    private static string Normalize(string path) => path.Trim('/');
+
+    private sealed class Unregister : IDisposable
+    {
+        private readonly WebhookRegistry _owner;
+        private readonly Key _key;
+        public Unregister(WebhookRegistry o, Key k) { _owner = o; _key = k; }
+        public void Dispose() => _owner._routes.TryRemove(_key, out _);
+    }
+}

src/VolcanicCore.Api/Program.cs

@@ -118,6 +118,7 @@ builder.Services.AddSingleton<IConnectionInstanceRegistry>(sp =>
     sp.GetRequiredService<ConnectionInstanceRegistry>());
 
 builder.Services.AddSingleton<WebhookRouter>();
+builder.Services.AddSingleton<WebhookRegistry>();
 
 var app = builder.Build();