[Bug] OpenCode steals foreground focus and disrupts user workflow when testing/running apps (Window Activation / Focus Stealing) #57578

Description

Description

When OpenCode executes tasks in the background that involve launching, testing, or inspecting an application, the target application window forcefully launches into the foreground active window. This steals OS-level keyboard/mouse focus from whichever window the user is currently working in (e.g., code editor, browser, notes).

Actual Behavior

• Running an app or background test in OpenCode pops the application window directly on top of active work.
• Focus is stolen from the active window, causing mid-sentence typing interruptions.
• The user has to manually re-focus their active application every time OpenCode runs or tests a UI build.

Expected Behavior

OpenCode should execute background app checks, previews, and UI tests without taking active window focus away from the user's primary workspace.

Testing and UI inspection tasks should run:

• Headless or Off-Screen: Virtual framebuffers or hidden rendering contexts so no physical window disrupts the desktop.
• Without Focus Activation: If a GUI window must open, it should launch in a non-activating background layer (SHOWNOACTIVATE / non-activating window flags) so typing and work in the foreground are never interrupted.

Steps to Reproduce

1. Open a workspace in OpenCode.
2. Trigger an action or agent task that executes or tests a target application.
3. Switch to another app and begin typing or editing.
4. Observe: The application spawned by OpenCode pops into the active foreground, stealing focus and interrupting work.

Here are the additional details to help debug this issue:

1. OpenCode version: OpenCode Desktop Version 2.1.2 (running on macOS, Apple Silicon / M1).
2. Interface: OpenCode Desktop App.
3. What took focus & command ran:
   • The app taking focus is the desktop application under development in the workspace (for example, myapp.app).
   • The focus-stealing occurs when OpenCode runs/launches the compiled desktop app binary during background test/build cycles (e.g., executing the app directly via shell commands or open myapp.app without the -g background flag).
   • It is not the OpenCode built-in browser taking focus—it is the local macOS target application being tested.
4. Summary of behavior:
   I was actively dictating text and working in another application (such as Notepad/TextEdit) while OpenCode was running background tasks on my project in the OpenCode Desktop app. While OpenCode was executing/testing the local desktop app build (myapp.app), the launched app window forcefully opened in the OS foreground. This stole system-level keyboard focus mid-dictation/mid-typing, causing text input to drop or lose target window state, and interrupting active media playback (like YouTube) by popping over the workspace.

Key issue:
When OpenCode spawns or runs target macOS application binaries to verify or test UI work, it launches them as activated foreground processes rather than executing them quietly in the background (e.g., using open -g on macOS, non-activating window flags, or headless preview wrappers).