From 5be8638e22fcb6dd2c33992377e06c020d0960cc Mon Sep 17 00:00:00 2001
From: danielku15 <danielku15@coderline.net>
Date: Wed, 7 Oct 2026 12:49:48 +0200
Subject: [PATCH 1/2] test(player): cover late midiLoaded registration with the
 worker player

---
 .../test/audio/AlphaSynthWebWorkerApi.test.ts | 61 +++++++++++++++++++
 1 file changed, 61 insertions(+)
 create mode 100644 packages/alphatab/test/audio/AlphaSynthWebWorkerApi.test.ts

diff --git a/packages/alphatab/test/audio/AlphaSynthWebWorkerApi.test.ts b/packages/alphatab/test/audio/AlphaSynthWebWorkerApi.test.ts
new file mode 100644
index 000000000..2aebe3b29
--- /dev/null
+++ b/packages/alphatab/test/audio/AlphaSynthWebWorkerApi.test.ts
@@ -0,0 +1,61 @@
+/**
+ * Tests for the main-thread side of the worker based player. Feeds worker messages
+ * directly as plain objects, so web-only.
+ *
+ * @target web
+ */
+
+import { AlphaSynthWebWorkerApi } from '@coderline/alphatab/platform/worker/AlphaSynthWebWorkerApi';
+import type {
+    IAlphaSynthWorker,
+    IAlphaSynthWorkerMessage
+} from '@coderline/alphatab/platform/worker/AlphaTabWorkerProtocol';
+import { Settings } from '@coderline/alphatab/Settings';
+import { AlphaSynthWrapper } from '@coderline/alphatab/synth/AlphaSynthWrapper';
+import { PositionChangedEventArgs } from '@coderline/alphatab/synth/PositionChangedEventArgs';
+import { TestOutput } from 'test/audio/TestOutput';
+import { describe, expect, it } from 'vitest';
+
+class TestSynthWorker implements IAlphaSynthWorker {
+    public postMessage(_message: IAlphaSynthWorkerMessage): void {
+        // nothing to do
+    }
+
+    public addEventListener(_event: 'message', _handler: (ev: MessageEvent<IAlphaSynthWorkerMessage>) => void): void {
+        // nothing to do
+    }
+
+    public removeEventListener(
+        _event: 'message',
+        _handler: (ev: MessageEvent<IAlphaSynthWorkerMessage>) => void
+    ): void {
+        // nothing to do
+    }
+
+    public terminate(): void {
+        // nothing to do
+    }
+}
+
+describe('AlphaSynthWebWorkerApiTests', () => {
+    it('midi-loaded-late-registration', () => {
+        const workerApi = new AlphaSynthWebWorkerApi(new TestOutput(), new Settings(), new TestSynthWorker());
+        const wrapper = new AlphaSynthWrapper();
+        wrapper.instance = workerApi;
+
+        workerApi.handleWorkerMessage({
+            data: {
+                cmd: 'alphaSynth.midiLoaded',
+                args: new PositionChangedEventArgs(0, 2000, 0, 3840, false, 120, 120)
+            }
+        } as MessageEvent<IAlphaSynthWorkerMessage>);
+
+        expect(wrapper.loadedMidiInfo?.endTick).toBe(3840);
+
+        const received: PositionChangedEventArgs[] = [];
+        wrapper.midiLoaded.on(e => received.push(e));
+        expect(received.length).toBe(1);
+        expect(received[0].endTick).toBe(3840);
+        expect(received[0].endTime).toBe(2000);
+    });
+});

From 3c16949be9f4df44b6d2b2ef7ea7e22892cde783 Mon Sep 17 00:00:00 2001
From: danielku15 <danielku15@coderline.net>
Date: Wed, 7 Oct 2026 12:51:34 +0200
Subject: [PATCH 2/2] fix(player): return stored loaded MIDI info from worker
 player API

The loadedMidiInfo getter returned itself instead of the backing field,
so any late midiLoaded registration recursed until the stack overflowed.

Fixes #2862
---
 packages/alphatab/src/platform/worker/AlphaSynthWebWorkerApi.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/alphatab/src/platform/worker/AlphaSynthWebWorkerApi.ts b/packages/alphatab/src/platform/worker/AlphaSynthWebWorkerApi.ts
index 2c757fd2c..2905ba46a 100644
--- a/packages/alphatab/src/platform/worker/AlphaSynthWebWorkerApi.ts
+++ b/packages/alphatab/src/platform/worker/AlphaSynthWebWorkerApi.ts
@@ -144,7 +144,7 @@ export class AlphaSynthWebWorkerApi implements IAlphaSynth {
     }
 
     public get loadedMidiInfo(): PositionChangedEventArgs | undefined {
-        return this.loadedMidiInfo;
+        return this._loadedMidiInfo;
     }
 
     public get currentPosition(): PositionChangedEventArgs {