diff --git a/README.md b/README.md
index 777cc86..3bd7b3c 100644
--- a/README.md
+++ b/README.md
@@ -30,6 +30,12 @@ Terminal UI for managing git worktrees and launching your preferred coding tool
 npm i -g opencode-worktree
 ```
 
+Or run it without a global installation using Bun:
+
+```bash
+bunx opencode-worktree
+```
+
 ## Run
 
 ```bash
diff --git a/bin/opencode-worktree b/bin/opencode-worktree
index 9580059..9620b6c 100755
--- a/bin/opencode-worktree
+++ b/bin/opencode-worktree
@@ -2,9 +2,9 @@
 
 import fs from 'node:fs';
 import path from 'node:path';
-import os from 'node:os';
 import { spawn } from 'node:child_process';
 import { fileURLToPath } from 'node:url';
+import { getBinaryPath, installBinary } from '../script/runtime.mjs';
 
 const __filename = fileURLToPath(import.meta.url);
 const __dirname = path.dirname(__filename);
@@ -12,56 +12,19 @@ const pkg = JSON.parse(
   fs.readFileSync(new URL('../package.json', import.meta.url), 'utf8'),
 );
 
-const detectPlatformAndArch = () => {
-  let platform;
-  switch (os.platform()) {
-    case 'darwin':
-      platform = 'darwin';
-      break;
-    case 'linux':
-      platform = 'linux';
-      break;
-    case 'win32':
-      platform = 'windows';
-      break;
-    default:
-      platform = os.platform();
-      break;
-  }
-
-  let arch;
-  switch (os.arch()) {
-    case 'x64':
-      arch = 'x64';
-      break;
-    case 'arm64':
-      arch = 'arm64';
-      break;
-    default:
-      arch = os.arch();
-      break;
-  }
-
-  return { platform, arch };
-};
-
-const resolveBinaryPath = () => {
-  const { platform } = detectPlatformAndArch();
-  const binaryName = platform === 'windows' ? 'opencode-worktree.exe' : 'opencode-worktree-bin';
-  const binaryPath = path.join(__dirname, '..', 'bin', binaryName);
-
+const resolveBinaryPath = async () => {
+  const packageRoot = path.join(__dirname, '..');
+  const { binaryPath } = getBinaryPath(packageRoot);
   if (!fs.existsSync(binaryPath)) {
-    throw new Error(
-      `Binary not found at ${binaryPath}. Run npm install -g ${pkg.name} again to re-download.`,
-    );
+    console.error('Downloading opencode-worktree binary...');
+    await installBinary(packageRoot, pkg.version);
   }
-
   return binaryPath;
 };
 
-const run = () => {
+const run = async () => {
   try {
-    const binaryPath = resolveBinaryPath();
+    const binaryPath = await resolveBinaryPath();
     const args = process.argv.slice(2);
     const child = spawn(binaryPath, args, { stdio: 'inherit' });
 
diff --git a/script/postinstall.mjs b/script/postinstall.mjs
index 8a006ad..fdcf335 100644
--- a/script/postinstall.mjs
+++ b/script/postinstall.mjs
@@ -2,78 +2,19 @@
 
 import fs from "node:fs";
 import path from "node:path";
-import os from "node:os";
 import { fileURLToPath } from "node:url";
+import { getBinaryPath, installBinary as downloadBinary } from "./runtime.mjs";
 
 const __dirname = path.dirname(fileURLToPath(import.meta.url));
 const pkg = JSON.parse(
   fs.readFileSync(path.join(__dirname, "..", "package.json"), "utf8"),
 );
 
-const detectPlatformAndArch = () => {
-  let platform;
-  switch (os.platform()) {
-    case "darwin":
-      platform = "darwin";
-      break;
-    case "linux":
-      platform = "linux";
-      break;
-    case "win32":
-      platform = "windows";
-      break;
-    default:
-      platform = os.platform();
-      break;
-  }
-
-  let arch;
-  switch (os.arch()) {
-    case "x64":
-      arch = "x64";
-      break;
-    case "arm64":
-      arch = "arm64";
-      break;
-    default:
-      arch = os.arch();
-      break;
-  }
-
-  return { platform, arch };
-};
-
-const downloadFile = async (url, targetPath) => {
-  const response = await fetch(url);
-  if (!response.ok) {
-    throw new Error(`Failed to download ${url} (${response.status})`);
-  }
-
-  const buffer = Buffer.from(await response.arrayBuffer());
-  fs.writeFileSync(targetPath, buffer);
-};
-
 const installBinary = async () => {
-  const { platform, arch } = detectPlatformAndArch();
-  const isWindows = platform === "windows";
-  const binaryName = isWindows
-    ? "opencode-worktree.exe"
-    : "opencode-worktree-bin";
-  const downloadName = `opencode-worktree-${platform}-${arch}${isWindows ? ".exe" : ""}`;
-  const version = pkg.version;
-  const downloadUrl = `https://github.com/arturosdg/opencode-worktree/releases/download/v${version}/${downloadName}`;
-
-  const binDir = path.join(__dirname, "..", "bin");
-  const binaryPath = path.join(binDir, binaryName);
-
-  fs.mkdirSync(binDir, { recursive: true });
-  await downloadFile(downloadUrl, binaryPath);
-
-  if (!isWindows) {
-    fs.chmodSync(binaryPath, 0o755);
-  }
-
-  return binaryPath;
+  const packageRoot = path.join(__dirname, "..");
+  const { binaryPath } = getBinaryPath(packageRoot);
+  if (fs.existsSync(binaryPath)) return binaryPath;
+  return downloadBinary(packageRoot, pkg.version);
 };
 
 try {
diff --git a/script/runtime.mjs b/script/runtime.mjs
new file mode 100644
index 0000000..eeea55c
--- /dev/null
+++ b/script/runtime.mjs
@@ -0,0 +1,28 @@
+import fs from "node:fs";
+import os from "node:os";
+import path from "node:path";
+
+const detectPlatformAndArch = () => ({
+  platform: { darwin: "darwin", linux: "linux", win32: "windows" }[os.platform()] ?? os.platform(),
+  arch: { x64: "x64", arm64: "arm64" }[os.arch()] ?? os.arch(),
+});
+
+export const getBinaryPath = (packageRoot) => {
+  const { platform } = detectPlatformAndArch();
+  const binaryName = platform === "windows" ? "opencode-worktree.exe" : "opencode-worktree-bin";
+  return { binaryPath: path.join(packageRoot, "bin", binaryName), binaryName };
+};
+
+export const installBinary = async (packageRoot, version) => {
+  const { platform, arch } = detectPlatformAndArch();
+  const isWindows = platform === "windows";
+  const downloadName = `opencode-worktree-${platform}-${arch}${isWindows ? ".exe" : ""}`;
+  const downloadUrl = `https://github.com/arturosdg/opencode-worktree/releases/download/v${version}/${downloadName}`;
+  const { binaryPath } = getBinaryPath(packageRoot);
+  const response = await fetch(downloadUrl);
+  if (!response.ok) throw new Error(`Failed to download ${downloadUrl} (${response.status})`);
+  fs.mkdirSync(path.dirname(binaryPath), { recursive: true });
+  fs.writeFileSync(binaryPath, Buffer.from(await response.arrayBuffer()));
+  if (!isWindows) fs.chmodSync(binaryPath, 0o755);
+  return binaryPath;
+};