From 4c4177c471aac494ba5a90ef524b395aca8a8ace Mon Sep 17 00:00:00 2001
From: June Kim <kimjune01@gmail.com>
Date: Mon, 11 May 2026 22:19:04 -0700
Subject: [PATCH 1/2] test: reproduce #73 (fails on main)

TypeScript rejects core.on('metro', callback) because 'metro' is
missing from the EventTypes type definition in Events.ts, even though
the wasm runtime emits metro events at runtime.
---
 .../core/__tests__/metro-event-type.test.ts    | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 js/packages/core/__tests__/metro-event-type.test.ts

diff --git a/js/packages/core/__tests__/metro-event-type.test.ts b/js/packages/core/__tests__/metro-event-type.test.ts
new file mode 100644
index 00000000..2e5d2a13
--- /dev/null
+++ b/js/packages/core/__tests__/metro-event-type.test.ts
@@ -0,0 +1,18 @@
+/**
+ * Type-level test for metro event type.
+ *
+ * This test verifies that 'metro' is recognized as a valid event name
+ * in EventTypes, so that core.on('metro', callback) compiles without
+ * TypeScript errors.
+ *
+ * See: https://github.com/elemaudio/elementary/issues/73
+ */
+import EventEmitter from '../src/Events';
+
+// This should compile without errors: metro is a valid event type
+const emitter = new EventEmitter();
+
+emitter.on('metro', (data) => {
+  // The metro event payload should have an optional source field
+  const source: string | undefined = data.source;
+});

From d68597cf22edf2117ab426a49935d31f91719e02 Mon Sep 17 00:00:00 2001
From: June Kim <kimjune01@gmail.com>
Date: Mon, 11 May 2026 22:28:44 -0700
Subject: [PATCH 2/2] fix: add metro to EventTypes interface

Adds the metro event type signature to match the C++ MetronomeNode's
processEvents output. The event payload contains an optional source
field populated from the node's name property.

Fixes #73
---
 js/packages/core/src/Events.ts | 1 +
 1 file changed, 1 insertion(+)

diff --git a/js/packages/core/src/Events.ts b/js/packages/core/src/Events.ts
index 8a06949b..31046aca 100644
--- a/js/packages/core/src/Events.ts
+++ b/js/packages/core/src/Events.ts
@@ -7,6 +7,7 @@ type EventTypes = {
   fft: (data: { source?: string, data: { real: Float32Array, imag: Float32Array } }) => void;
   load: () => void;
   meter: (data: { source?: string, min: number; max: number, }) => void;
+  metro: (data: { source?: string }) => void;
   scope: (data: { source?: string, data: Float32Array[] }) => void;
   snapshot: (data: { source?: string, data: number }) => void;
 };