diff --git a/Makefile b/Makefile
index 7e5762e..3759424 100644
--- a/Makefile
+++ b/Makefile
@@ -54,6 +54,7 @@ package: build resolve-deps ## Build installable app for the current platform
 	@$(PNPM) --dir packages/electron dist
 
 package-mac: build resolve-deps ## Build .dmg for macOS (current arch)
+	@hdiutil detach /Volumes/Dune -force 2>/dev/null || true
 	@$(PNPM) --dir packages/electron dist:mac -- --$(shell uname -m | sed 's/x86_64/x64/')
 
 package-linux: build resolve-deps ## Build .AppImage/.deb for Linux
diff --git a/packages/backend/src/agents/agent-manager.ts b/packages/backend/src/agents/agent-manager.ts
index 4be74bd..a7f4dcd 100644
--- a/packages/backend/src/agents/agent-manager.ts
+++ b/packages/backend/src/agents/agent-manager.ts
@@ -631,12 +631,13 @@ async function ensureCliInstalled(box: SimpleBox): Promise<void> {
   console.log('Claude CLI:', check.stdout.trim())
 }
 
-/** Read the current backend port from the .port file.
- *  server.ts writes it to join(__dirname, '../.port') from src/,
- *  which is packages/backend/.port. From src/agents/, that's ../../.port. */
+/** Returns the agent-facing backend port.
+ *  In packaged mode the sidecar passes PORT via env -> config.port.
+ *  In dev mode we fall back to the .port file written by server.ts. */
 function getBackendPort(): number {
+  if (config.port > 0) return config.port
   try {
-    const portFile = join(__dirname, '../../.port')
+    const portFile = join(__dirname, '../.port')
     const raw = readFileSync(portFile, 'utf-8').trim()
     if (raw.startsWith('{')) {
       const parsed = JSON.parse(raw)
diff --git a/packages/backend/test/agent-system-prompt.test.ts b/packages/backend/test/agent-system-prompt.test.ts
index 22fb7e0..65f0006 100644
--- a/packages/backend/test/agent-system-prompt.test.ts
+++ b/packages/backend/test/agent-system-prompt.test.ts
@@ -95,6 +95,6 @@ test('bundled asset resolver falls back from dist to src assets', () => {
   )
   assert.equal(
     agentManager.__resolveBundledAssetDirForTests('agent-mcp', resolve(backendRoot, 'dist')),
-    resolve(backendRoot, 'src', 'agent-mcp'),
+    resolve(backendRoot, 'src', 'agents', 'mcp'),
   )
 })
diff --git a/packages/electron/electron-builder.yml b/packages/electron/electron-builder.yml
index 90cda36..2d8c8e5 100644
--- a/packages/electron/electron-builder.yml
+++ b/packages/electron/electron-builder.yml
@@ -33,7 +33,7 @@ extraResources:
     filter:
       - "**/*"
 
-  - from: ../backend/src/agent-mcp
+  - from: ../backend/src/agents/mcp
     to: backend/agent-mcp
     filter:
       - "**/*.py"
@@ -53,14 +53,8 @@ npmRebuild: true
 mac:
   category: public.app-category.developer-tools
   target:
-    - target: dmg
-      arch:
-        - arm64
-        - x64
-    - target: zip
-      arch:
-        - arm64
-        - x64
+    - dmg
+    - zip
   icon: assets/icon.icns
   darkModeSupport: true
   hardenedRuntime: true
@@ -69,6 +63,7 @@ mac:
 dmg:
   sign: false
   title: Dune
+  backgroundColor: '#ffffff'
 
 linux:
   target:
diff --git a/packages/electron/src/util/paths.ts b/packages/electron/src/util/paths.ts
index fbeb6d1..f704bb5 100644
--- a/packages/electron/src/util/paths.ts
+++ b/packages/electron/src/util/paths.ts
@@ -55,7 +55,7 @@ export function getAgentMcpPath(): string {
   if (isPackaged()) {
     return join(process.resourcesPath!, 'backend', 'agent-mcp')
   }
-  return resolve(getRepoRoot(), 'packages', 'backend', 'src', 'agent-mcp')
+  return resolve(getRepoRoot(), 'packages', 'backend', 'src', 'agents', 'mcp')
 }
 
 export function getAgentPromptsPath(): string {