fix(cli): select arm64 binary under Rosetta

scripts/install.sh

@@ -74,6 +74,12 @@ detect_platform() {
     *)       error "Unsupported OS: $OS" ;;
   esac
 
+  if [ "$OS" = "darwin" ] && [ "$ARCH" = "x86_64" ] && command -v sysctl >/dev/null 2>&1; then
+    if [ "$(sysctl -in sysctl.proc_translated 2>/dev/null || true)" = "1" ]; then
+      ARCH="arm64"
+    fi
+  fi
+
   case "$ARCH" in
     x86_64|amd64)  ARCH="x64" ;;
     aarch64|arm64) ARCH="arm64" ;;

src/platform.ts

@@ -0,0 +1,56 @@
+import { execFileSync } from 'child_process';
+import { arch, platform } from 'os';
+
+export interface RuntimePlatform {
+  platform: NodeJS.Platform | string;
+  arch: string;
+  isTranslated?: boolean;
+}
+
+/**
+ * Rosetta reports the process as x64 even on Apple Silicon. For release
+ * binaries, choose the native machine architecture so macOS installs can
+ * replace a translated x64 binary with the arm64 build.
+ */
+export function resolvePlatformKey(runtime: RuntimePlatform): string {
+  const p = runtime.platform;
+  let a = runtime.arch;
+
+  if (p === 'darwin' && a === 'x64' && runtime.isTranslated) {
+    a = 'arm64';
+  }
+
+  if (p === 'darwin') {
+    return a === 'arm64' ? 'darwin-arm64' : 'darwin-x64';
+  } else if (p === 'linux') {
+    return a === 'arm64' ? 'linux-arm64' : 'linux-x64';
+  } else if (p === 'win32') {
+    return 'win32-x64';
+  }
+
+  return `${p}-${a}`;
+}
+
+function isRosettaTranslated(): boolean {
+  if (platform() !== 'darwin' || arch() !== 'x64') {
+    return false;
+  }
+
+  try {
+    const output = execFileSync('/usr/sbin/sysctl', ['-in', 'sysctl.proc_translated'], {
+      encoding: 'utf8',
+      stdio: ['ignore', 'pipe', 'ignore'],
+    }).trim();
+    return output === '1';
+  } catch {
+    return false;
+  }
+}
+
+export function getPlatformKey(): string {
+  return resolvePlatformKey({
+    platform: platform(),
+    arch: arch(),
+    isTranslated: isRosettaTranslated(),
+  });
+}

src/updater.test.ts

@@ -0,0 +1,24 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { resolvePlatformKey } from './platform.ts';
+
+test('resolvePlatformKey: uses arm64 artifact for translated Apple Silicon processes', () => {
+  assert.equal(
+    resolvePlatformKey({ platform: 'darwin', arch: 'x64', isTranslated: true }),
+    'darwin-arm64',
+  );
+});
+
+test('resolvePlatformKey: keeps native Intel macOS on x64 artifact', () => {
+  assert.equal(
+    resolvePlatformKey({ platform: 'darwin', arch: 'x64', isTranslated: false }),
+    'darwin-x64',
+  );
+});
+
+test('resolvePlatformKey: keeps non-macOS platform mapping unchanged', () => {
+  assert.equal(
+    resolvePlatformKey({ platform: 'linux', arch: 'arm64', isTranslated: true }),
+    'linux-arm64',
+  );
+});

src/updater.ts

@@ -2,11 +2,12 @@
 
 import { existsSync, createWriteStream, unlinkSync, chmodSync, renameSync } from 'fs';
 import { join, dirname } from 'path';
-import { homedir, platform, arch } from 'os';
+import { homedir } from 'os';
 import { pipeline } from 'stream/promises';
 import { Readable } from 'stream';
 import semver from 'semver';
 import { VERSION, CYAN, GREEN, YELLOW, RED, RESET, DIM } from './constants.ts';
+import { getPlatformKey } from './platform.ts';
 
 const UPDATE_CHECK_FILE = join(homedir(), '.askill', 'last-update-check');
 const UPDATE_INTERVAL_MS = 24 * 60 * 60 * 1000; // 24 hours
@@ -28,24 +29,6 @@ export interface AvailableUpdate {
   releaseUrl?: string;
 }
 
-/**
- * Get platform key for download URL
- */
-function getPlatformKey(): string {
-  const p = platform();
-  const a = arch();
-
-  if (p === 'darwin') {
-    return a === 'arm64' ? 'darwin-arm64' : 'darwin-x64';
-  } else if (p === 'linux') {
-    return a === 'arm64' ? 'linux-arm64' : 'linux-x64';
-  } else if (p === 'win32') {
-    return 'win32-x64';
-  }
-
-  return `${p}-${a}`;
-}
-
 /**
  * Check if update check is needed
  */