opencode.exe fails with "Unsupported 16-Bit Application" error on Windows 10/11

[brandaltux]

Description

When trying to run `opencode` after a global installation via npm on Windows, it fails to execute and triggers a Windows system dialog error: "Unsupported 16-Bit Application. The program or feature '...\opencode.exe' cannot start or run due to incompatibility with 64-bit versions of Windows."

It seems the post-install script that should replace the placeholder .exe with the actual binary is either blocked or failing during the setup.
Steps to reproduce the behavior:

1. Run npm i -g opencode-ai (Notice the install-scripts blocked warning during installation).
2. Run opencode in PowerShell or Command Prompt.
3. See the "Unsupported 16-Bit Application" error pop-up.

Plugins

No response

OpenCode version

No response

Steps to reproduce

No response

Screenshot and/or share link

Operating System

Windows 10 Pro

Terminal

Windows Terminal

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• Windows: opencode-ai@1.17.19 global npm install leaves 479-byte placeholder opencode.exe when postinstall is blocked #36737: Same root cause — npm postinstall script blocked on Windows leaves the 479-byte placeholder opencode.exe, resulting in the "Unsupported 16-Bit Application" error. That issue also documents a workaround (manually running postinstall.mjs) and suggested fixes.