Implement parallel event handler support

Co-authored-by: twlite <[email protected]>

Author: Copilot

packages/commandkit/src/app/handlers/AppEventsHandler.ts

@@ -14,6 +14,7 @@ import { CommandKitErrorCodes, isErrorType } from '../../utils/error-codes';
 export type EventListener = {
   handler: ListenerFunction;
   once: boolean;
+  parallel: boolean;
 };
 
 /**
@@ -111,6 +112,7 @@ export class AppEventsHandler {
         listeners.push({
           handler: handler.default,
           once: !!handler.once,
+          parallel: !!handler.parallel,
         });
       }
 
@@ -164,6 +166,12 @@ export class AppEventsHandler {
       const onceListeners = listeners.filter((listener) => listener.once);
       const onListeners = listeners.filter((listener) => !listener.once);
 
+      // Further separate into parallel and sequential groups
+      const onParallelListeners = onListeners.filter((listener) => listener.parallel);
+      const onSequentialListeners = onListeners.filter((listener) => !listener.parallel);
+      const onceParallelListeners = onceListeners.filter((listener) => listener.parallel);
+      const onceSequentialListeners = onceListeners.filter((listener) => !listener.parallel);
+
       // Initialize set to track executed once listeners
       const executedOnceListeners = new Set<ListenerFunction>();
 
@@ -200,7 +208,24 @@ export class AppEventsHandler {
             variables: new Map(),
           },
           async () => {
-            for (const listener of onListeners) {
+            // Execute parallel listeners first using Promise.all
+            if (onParallelListeners.length > 0) {
+              await Promise.all(
+                onParallelListeners.map(async (listener) => {
+                  try {
+                    await listener.handler(...args, client, this.commandkit);
+                  } catch (e) {
+                    // Log errors but don't stop other parallel listeners
+                    Logger.error`Error handling event ${name}${
+                      namespace ? ` of namespace ${namespace}` : ''
+                    }: ${e}`;
+                  }
+                }),
+              );
+            }
+
+            // Execute sequential listeners in order
+            for (const listener of onSequentialListeners) {
               try {
                 await listener.handler(...args, client, this.commandkit);
               } catch (e) {
@@ -248,7 +273,40 @@ export class AppEventsHandler {
           })
           .catch(Object);
 
-        for (const listener of onceListeners) {
+        // Execute parallel once listeners first using Promise.all
+        if (onceParallelListeners.length > 0) {
+          await Promise.all(
+            onceParallelListeners.map(async (listener) => {
+              return runInEventWorkerContext(
+                {
+                  event: name,
+                  namespace: namespace ?? null,
+                  data: data.event,
+                  commandkit: this.commandkit,
+                  arguments: args,
+                  variables: new Map(),
+                },
+                async () => {
+                  try {
+                    // Skip if already executed
+                    if (executedOnceListeners.has(listener.handler)) return;
+
+                    await listener.handler(...args, client, this.commandkit);
+                    executedOnceListeners.add(listener.handler);
+                  } catch (e) {
+                    // Log errors but don't stop other parallel listeners
+                    Logger.error`Error handling event ${name}${
+                      namespace ? ` of namespace ${namespace}` : ''
+                    }: ${e}`;
+                  }
+                },
+              );
+            }),
+          );
+        }
+
+        // Execute sequential once listeners in order
+        for (const listener of onceSequentialListeners) {
           if (broken) break; // Stop executing remaining listeners if propagation was stopped
 
           await runInEventWorkerContext(
@@ -307,7 +365,7 @@ export class AppEventsHandler {
         ...data,
         mainListener:
           onListeners.length > 0
-            ? { handler: mainHandler, once: false }
+            ? { handler: mainHandler, once: false, parallel: false }
             : undefined,
         executedOnceListeners,
       });
@@ -332,7 +390,7 @@ export class AppEventsHandler {
       Logger.info(
         `🔌 Registered event ${name}${
           namespace ? ` of namespace ${namespace}` : ''
-        } (${onListeners.length} regular, ${onceListeners.length} once-only)`,
+        } (${onSequentialListeners.length} sequential, ${onParallelListeners.length} parallel, ${onceSequentialListeners.length} once-sequential, ${onceParallelListeners.length} once-parallel)`,
       );
     }
   }