Problem: opencode does not ship a windows-arm64 binary (issue #4340). The npm wrapper detects arm64 and fails with:
It seems that your package manager failed to install the right version of the opencode CLI for your platform.
You can try manually installing "opencode-windows-arm64" package
Solution: Force-install the x64 binary and set OPENCODE_BIN_PATH so the Node.js wrapper uses it directly. Windows 11 arm64 runs x86_64 binaries natively via its built-in emulation layer.