diff --git a/scripts/build-macos-effects.mjs b/scripts/build-macos-effects.mjs
index 1398095..0e8377e 100644
--- a/scripts/build-macos-effects.mjs
+++ b/scripts/build-macos-effects.mjs
@@ -5,7 +5,27 @@ import { fileURLToPath } from "node:url";
 
 const rootDir = path.resolve(path.dirname(fileURLToPath(import.meta.url)), "..");
 const srcFile = path.join(rootDir, "native/macos/window-effects.mm");
-const outFile = path.join(rootDir, "src/bun/libMacWindowEffects.dylib");
+export const outFile = path.join(rootDir, "src/bun/libMacWindowEffects.dylib");
+const minDylibBytes = 10_000;
+
+function normalizeArch(value) {
+  if (value === "x64" || value === "amd64" || value === "x86_64") {
+    return "x86_64";
+  }
+  if (value === "arm64" || value === "aarch64") {
+    return "arm64";
+  }
+  return null;
+}
+
+export function resolveTargetArch() {
+  return (
+    normalizeArch(process.env.ELECTROBUN_TARGET_ARCH) ||
+    normalizeArch(process.env.ELECTROBUN_ARCH) ||
+    normalizeArch(process.arch) ||
+    "arm64"
+  );
+}
 
 function createPlaceholder() {
   mkdirSync(path.dirname(outFile), { recursive: true });
@@ -13,6 +33,49 @@ function createPlaceholder() {
   console.log(`build-macos-effects: created placeholder dylib at ${outFile}`);
 }
 
+function readDylibArch(dylibPath) {
+  const lipo = spawnSync("lipo", ["-info", dylibPath], { encoding: "utf8" });
+  if (lipo.status === 0) {
+    return lipo.stdout;
+  }
+
+  const file = spawnSync("file", ["-b", dylibPath], { encoding: "utf8" });
+  return file.stdout || "";
+}
+
+export function validateMacosEffectsDylib({
+  dylibPath = outFile,
+  expectedArch = resolveTargetArch(),
+  required = process.platform === "darwin",
+} = {}) {
+  if (!required) {
+    return true;
+  }
+
+  if (!existsSync(dylibPath)) {
+    console.error(`build-macos-effects: missing dylib at ${dylibPath}`);
+    return false;
+  }
+
+  const { size } = statSync(dylibPath);
+  if (size < minDylibBytes) {
+    console.error(
+      `build-macos-effects: dylib at ${dylibPath} is too small (${size} bytes)`,
+    );
+    return false;
+  }
+
+  const archInfo = readDylibArch(dylibPath);
+  if (!archInfo.includes(expectedArch)) {
+    console.error(
+      `build-macos-effects: dylib architecture mismatch (expected ${expectedArch}): ${archInfo.trim()}`,
+    );
+    return false;
+  }
+
+  return true;
+}
+
 if (process.platform !== "darwin") {
   createPlaceholder();
   process.exit(0);
@@ -25,12 +88,16 @@ if (!existsSync(srcFile)) {
 
 mkdirSync(path.dirname(outFile), { recursive: true });
 
+const targetArch = resolveTargetArch();
 const result = spawnSync(
   "xcrun",
   [
     "clang++",
     "-dynamiclib",
     "-fobjc-arc",
+    "-arch",
+    targetArch,
+    "-mmacosx-version-min=11.0",
     "-framework",
     "Cocoa",
     srcFile,
@@ -44,5 +111,11 @@ if (result.status !== 0) {
   process.exit(result.status ?? 1);
 }
 
+if (!validateMacosEffectsDylib({ dylibPath: outFile, expectedArch: targetArch })) {
+  process.exit(1);
+}
+
 const { size } = statSync(outFile);
-console.log(`build-macos-effects: built ${outFile} (${size} bytes)`);
+console.log(
+  `build-macos-effects: built ${outFile} (${size} bytes, arch=${targetArch})`,
+);
diff --git a/scripts/pre-build.mjs b/scripts/pre-build.mjs
index 32046ce..307eba0 100644
--- a/scripts/pre-build.mjs
+++ b/scripts/pre-build.mjs
@@ -1,7 +1,7 @@
 import { existsSync, mkdirSync, writeFileSync } from "node:fs";
 import path from "node:path";
 import { spawnSync } from "node:child_process";
-import { fileURLToPath } from "node:url";
+import { fileURLToPath, pathToFileURL } from "node:url";
 
 const rootDir = path.resolve(path.dirname(fileURLToPath(import.meta.url)), "..");
 const buildEnv = process.env.ELECTROBUN_BUILD_ENV || "dev";
@@ -46,6 +46,21 @@ if (buildMacosEffects.status !== 0) {
   process.exit(buildMacosEffects.status ?? 1);
 }
 
+if (process.platform === "darwin") {
+  const { validateMacosEffectsDylib, outFile } = await import(
+    pathToFileURL(
+      path.join(rootDir, "scripts/build-macos-effects.mjs"),
+    ).href
+  );
+
+  if (!validateMacosEffectsDylib({ dylibPath: outFile })) {
+    console.error(
+      "pre-build: macOS window effects dylib is missing or invalid; blur and traffic lights will not work in packaged builds.",
+    );
+    process.exit(1);
+  }
+}
+
 const prepareIcons = spawnSync(
   "bun",
   [
diff --git a/scripts/run-electrobun-build.mjs b/scripts/run-electrobun-build.mjs
index 29be7f0..7ad3f77 100644
--- a/scripts/run-electrobun-build.mjs
+++ b/scripts/run-electrobun-build.mjs
@@ -1,6 +1,6 @@
 import { spawnSync } from "node:child_process";
 import path from "node:path";
-import { fileURLToPath } from "node:url";
+import { fileURLToPath, pathToFileURL } from "node:url";
 import { getReleaseArch } from "./release-artifact-utils.mjs";
 
 const rootDir = path.resolve(path.dirname(fileURLToPath(import.meta.url)), "..");
@@ -36,6 +36,21 @@ if (macosEffectsResult.status !== 0) {
   process.exit(macosEffectsResult.status ?? 1);
 }
 
+if (process.platform === "darwin") {
+  const { validateMacosEffectsDylib, outFile } = await import(
+    pathToFileURL(
+      path.join(rootDir, "scripts/build-macos-effects.mjs"),
+    ).href
+  );
+
+  if (!validateMacosEffectsDylib({ dylibPath: outFile })) {
+    console.error(
+      "run-electrobun-build: macOS window effects dylib is missing or invalid.",
+    );
+    process.exit(1);
+  }
+}
+
 const ensureCoreEnv = {
   ...process.env,
   ELECTROBUN_TARGET_ARCH: targetArch,
diff --git a/src/desktop/macos-window-effects.js b/src/desktop/macos-window-effects.js
index b953f34..aafa3cc 100644
--- a/src/desktop/macos-window-effects.js
+++ b/src/desktop/macos-window-effects.js
@@ -4,22 +4,38 @@ import path from 'node:path'
 import { fileURLToPath } from 'node:url'
 
 export const MAC_WINDOW_CORNER_RADIUS = 15
+export const MAC_TRAFFIC_LIGHT_OFFSET = { x: 14, y: 12 }
+
+const DYLIB_NAME = 'libMacWindowEffects.dylib'
+const MIN_DYLIB_BYTES = 10_000
 
 function resolveDylibPath() {
+  const candidates = new Set()
   const moduleDir = path.dirname(fileURLToPath(import.meta.url))
-  const candidates = [
-    path.join(moduleDir, '../bun/libMacWindowEffects.dylib'),
-    path.join(moduleDir, 'libMacWindowEffects.dylib')
-  ]
+
+  candidates.add(path.join(moduleDir, DYLIB_NAME))
+  candidates.add(path.join(moduleDir, '../bun', DYLIB_NAME))
+  candidates.add(path.join(moduleDir, '../../bun', DYLIB_NAME))
+  candidates.add(path.join(process.cwd(), 'src/bun', DYLIB_NAME))
+
+  for (const execPath of [process.execPath, process.argv0].filter(Boolean)) {
+    const execDir = path.dirname(execPath)
+    candidates.add(
+      path.join(execDir, '../Resources/app/bun', DYLIB_NAME)
+    )
+    candidates.add(path.join(execDir, 'Resources/app/bun', DYLIB_NAME))
+    candidates.add(path.join(execDir, DYLIB_NAME))
+  }
 
   for (const candidate of candidates) {
-    if (!existsSync(candidate)) {
+    const resolved = path.resolve(candidate)
+    if (!existsSync(resolved)) {
       continue
     }
 
     try {
-      if (statSync(candidate).size > 0) {
-        return candidate
+      if (statSync(resolved).size >= MIN_DYLIB_BYTES) {
+        return resolved
       }
     } catch {
       // Ignore unreadable paths and keep searching.
@@ -29,50 +45,99 @@ function resolveDylibPath() {
   return null
 }
 
-export function applyMacOSWindowEffects(mainWindow) {
-  if (process.platform !== 'darwin' || !mainWindow?.ptr) {
-    return
-  }
-
+function loadMacWindowEffectsLibrary() {
   const dylibPath = resolveDylibPath()
   if (!dylibPath) {
     console.warn(
       'macOS vibrancy: native effects library not found; using transparent window only.'
     )
-    return
+    return null
   }
 
   try {
-    const lib = dlopen(dylibPath, {
-      enableWindowVibrancy: {
-        args: [FFIType.ptr, FFIType.f64],
-        returns: FFIType.bool
-      },
-      ensureWindowShadow: {
-        args: [FFIType.ptr],
-        returns: FFIType.bool
-      },
-      setWindowCornerRadius: {
-        args: [FFIType.ptr, FFIType.f64],
-        returns: FFIType.bool
-      }
-    })
+    return {
+      path: dylibPath,
+      lib: dlopen(dylibPath, {
+        enableWindowVibrancy: {
+          args: [FFIType.ptr, FFIType.f64],
+          returns: FFIType.bool
+        },
+        ensureWindowShadow: {
+          args: [FFIType.ptr],
+          returns: FFIType.bool
+        },
+        setWindowCornerRadius: {
+          args: [FFIType.ptr, FFIType.f64],
+          returns: FFIType.bool
+        },
+        setWindowTrafficLightsPosition: {
+          args: [FFIType.ptr, FFIType.f64, FFIType.f64],
+          returns: FFIType.bool
+        },
+        setNativeWindowDragRegion: {
+          args: [FFIType.ptr, FFIType.f64, FFIType.f64],
+          returns: FFIType.bool
+        }
+      })
+    }
+  } catch (error) {
+    console.warn(
+      `macOS vibrancy: failed to load native effects library (${dylibPath}):`,
+      error
+    )
+    return null
+  }
+}
 
+function applyTrafficLightsPosition(lib, mainWindow, attempt = 0) {
+  const applied = lib.symbols.setWindowTrafficLightsPosition(
+    mainWindow.ptr,
+    MAC_TRAFFIC_LIGHT_OFFSET.x,
+    MAC_TRAFFIC_LIGHT_OFFSET.y
+  )
+
+  if (applied || attempt >= 10) {
+    return applied
+  }
+
+  setTimeout(() => applyTrafficLightsPosition(lib, mainWindow, attempt + 1), 50)
+  return false
+}
+
+export function applyMacOSWindowEffects(mainWindow) {
+  if (process.platform !== 'darwin' || !mainWindow?.ptr) {
+    return
+  }
+
+  const loaded = loadMacWindowEffectsLibrary()
+  if (!loaded) {
+    return
+  }
+
+  const { path: dylibPath, lib } = loaded
+
+  try {
     const vibrancyEnabled = lib.symbols.enableWindowVibrancy(
       mainWindow.ptr,
       MAC_WINDOW_CORNER_RADIUS
     )
     const shadowEnabled = lib.symbols.ensureWindowShadow(mainWindow.ptr)
+    const trafficLightsScheduled = applyTrafficLightsPosition(lib, mainWindow)
 
     mainWindow.on?.('resize', () => {
       lib.symbols.setWindowCornerRadius(
         mainWindow.ptr,
         MAC_WINDOW_CORNER_RADIUS
       )
+      lib.symbols.setWindowTrafficLightsPosition(
+        mainWindow.ptr,
+        MAC_TRAFFIC_LIGHT_OFFSET.x,
+        MAC_TRAFFIC_LIGHT_OFFSET.y
+      )
     })
 
     console.log(
-      `macOS vibrancy applied (vibrancy=${vibrancyEnabled}, shadow=${shadowEnabled}, cornerRadius=${MAC_WINDOW_CORNER_RADIUS})`
+      `macOS vibrancy applied (dylib=${dylibPath}, vibrancy=${vibrancyEnabled}, shadow=${shadowEnabled}, trafficLights=${trafficLightsScheduled}, cornerRadius=${MAC_WINDOW_CORNER_RADIUS})`
     )
   } catch (error) {
     console.warn(
diff --git a/src/desktop/window.js b/src/desktop/window.js
index 1e4f562..119dd5b 100644
--- a/src/desktop/window.js
+++ b/src/desktop/window.js
@@ -1,6 +1,9 @@
 import Electrobun, { BrowserWindow, Updater, Utils } from 'electrobun/bun'
 import { applyApplicationMenu, setupApplicationMenuEvents } from './menu.js'
-import { applyMacOSWindowEffects } from './macos-window-effects.js'
+import {
+  applyMacOSWindowEffects,
+  MAC_TRAFFIC_LIGHT_OFFSET
+} from './macos-window-effects.js'
 import { sendToRenderer, setMessageSender } from './notify.js'
 
 const isMacOS = process.platform === 'darwin'
@@ -137,7 +140,9 @@ export async function createMainWindow(rpc) {
     url,
     rpc,
     titleBarStyle: 'hiddenInset',
-    ...(isMacOS ? { transparent: true } : {}),
+    ...(isMacOS
+      ? { transparent: true, trafficLightOffset: MAC_TRAFFIC_LIGHT_OFFSET }
+      : {}),
     frame: {
       width: 1200,
       height: 800,