From 13119ef53b1015144633fd40c0f2a4125f2c5c97 Mon Sep 17 00:00:00 2001
From: Devin Ivy <devinivy@gmail.com>
Date: Wed, 8 Apr 2026 18:33:31 -0400
Subject: [PATCH] feat: Int32 non-atomic shared primitive

---
 src/index.ts              |  1 +
 src/shared/index.ts       |  1 +
 src/shared/int32.ts       | 28 ++++++++++++++++++++++++
 test/shared/int32.test.ts | 46 +++++++++++++++++++++++++++++++++++++++
 4 files changed, 76 insertions(+)
 create mode 100644 src/shared/int32.ts
 create mode 100644 test/shared/int32.test.ts

diff --git a/src/index.ts b/src/index.ts
index 672b7b5..8ba7926 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -5,6 +5,7 @@ export { transfer } from './transfer.ts';
 export type { Runner } from './runner.ts';
 export type { Loadable } from './shared/index.ts';
 export {
+  Int32,
   AtomicBool,
   AtomicInt8,
   AtomicUint8,
diff --git a/src/shared/index.ts b/src/shared/index.ts
index 8ecf09f..c28b6ea 100644
--- a/src/shared/index.ts
+++ b/src/shared/index.ts
@@ -1,4 +1,5 @@
 export type { Loadable } from './loadable.ts';
+export { Int32 } from './int32.ts';
 export { AtomicBool } from './atomic-bool.ts';
 export { AtomicInt8 } from './atomic-int8.ts';
 export { AtomicUint8 } from './atomic-uint8.ts';
diff --git a/src/shared/int32.ts b/src/shared/int32.ts
new file mode 100644
index 0000000..64292c7
--- /dev/null
+++ b/src/shared/int32.ts
@@ -0,0 +1,28 @@
+import { registerSync } from './reconstruct.ts';
+import type { Loadable } from './loadable.ts';
+
+export class Int32 implements Loadable<number> {
+  static readonly byteSize = 4;
+  static readonly byteAlignment = 4;
+  private readonly view: Int32Array;
+
+  constructor(buffer?: SharedArrayBuffer, byteOffset?: number) {
+    const buf = buffer ?? new SharedArrayBuffer(4);
+    const offset = byteOffset ?? 0;
+    this.view = new Int32Array(buf, offset, 1);
+  }
+
+  load(): number {
+    return this.view[0];
+  }
+
+  store(value: number): void {
+    this.view[0] = value;
+  }
+
+  [Symbol.for('moroutine.shared')](): { tag: string; buffer: SharedArrayBuffer; byteOffset: number } {
+    return { tag: 'Int32', buffer: this.view.buffer as SharedArrayBuffer, byteOffset: this.view.byteOffset };
+  }
+}
+
+registerSync('Int32', Int32);
diff --git a/test/shared/int32.test.ts b/test/shared/int32.test.ts
new file mode 100644
index 0000000..744591a
--- /dev/null
+++ b/test/shared/int32.test.ts
@@ -0,0 +1,46 @@
+import { describe, it } from 'node:test';
+import assert from 'node:assert/strict';
+import { Int32 } from 'moroutine';
+
+describe('Int32', () => {
+  it('self-allocates and initializes to zero', () => {
+    const v = new Int32();
+    assert.equal(v.load(), 0);
+  });
+
+  it('stores and loads a value', () => {
+    const v = new Int32();
+    v.store(42);
+    assert.equal(v.load(), 42);
+  });
+
+  it('accepts an external buffer and byteOffset', () => {
+    const buffer = new SharedArrayBuffer(16);
+    const v = new Int32(buffer, 4);
+    v.store(99);
+    assert.equal(new Int32Array(buffer, 4, 1)[0], 99);
+  });
+
+  it('defaults byteOffset to 0', () => {
+    const buffer = new SharedArrayBuffer(4);
+    const v = new Int32(buffer);
+    v.store(7);
+    assert.equal(new Int32Array(buffer)[0], 7);
+  });
+
+  it('exposes static byteSize of 4', () => {
+    assert.equal(Int32.byteSize, 4);
+  });
+
+  it('exposes static byteAlignment of 4', () => {
+    assert.equal(Int32.byteAlignment, 4);
+  });
+
+  it('does not use Atomics (plain read/write)', () => {
+    const buffer = new SharedArrayBuffer(4);
+    const v = new Int32(buffer);
+    v.store(123);
+    const raw = new Int32Array(buffer);
+    assert.equal(raw[0], 123);
+  });
+});
-- 
2.51.2