[Nix/macOS] Build fails with 'Operation not permitted' on Windows DLL - Regression since Jan 2026

[jerome-benoit]

Description

The Nix flake build for OpenCode fails on macOS with "Operation not permitted" error when trying to copy Windows DLL files during the install phase. This is a recent regression - the build was working on macOS before January 2026.

Error:

cp: cannot open './node_modules/.bun/@opentui+core-win32-x64@0.1.72/node_modules/@opentui/core-win32-x64/opentui.dll' for reading: Operation not permitted

Root cause: The installPhase in nix/opencode.nix attempts to copy ALL platform-specific binaries including Windows DLLs, which cannot be read on macOS.

Related to: #4853 (package size due to all platforms), #7540 (Arch Linux build failure)

Plugins

No response

OpenCode version

1.1.14

Steps to reproduce

1. On macOS, add OpenCode flake to your flake.nix:

inputs.opencode.url = "github:anomalyco/opencode";

2. Run home-manager switch or nix build github:anomalyco/opencode

3. Build fails during installPhase with "Operation not permitted" error on Windows DLL files

Screenshot and/or share link

Full error log:

error: Cannot build '/nix/store/7wfsv4gmzwha84hf6nbk25gvvk09n4hz-opencode-node_modules-1.1.14.drv'.
       > cp: cannot open './node_modules/.bun/@opentui+core-win32-x64@0.1.72/node_modules/@opentui/core-win32-x64/opentui.dll' for reading: Operation not permitted

Operating System

macOS (aarch64-darwin)

Terminal

iTerm2

[github-actions]

This issue is related to the known problem documented in #4853: When built from the Nix flake, OpenCode includes platform-specific binaries for all platforms (including Windows DLLs) instead of just the target platform.

This causes:

• Excessive package size (4GB+) as documented in When built from the flake, opencode package is extremely large (4GB+) #4853
• Build failures on non-Windows platforms when trying to copy Windows-specific files (like this issue)

Suggested solution: Implement platform-specific filtering in the Nix build to exclude non-target platform binaries during the install phase, as suggested in both issues.

Related issue for broader context: #4853

[jerome-benoit]

Regression Analysis

I've identified when the build started failing:

Breaking commit: d59357c (2026-01-01)
Title: "Update Nix flake.lock and hashes"
Trigger: This hash update followed release v1.0.222 which included commit c131dd0 "fix(desktop): Windows support for PTY and cross-platform build scripts (#6508)"

Root cause: The @opentui/core package has always had Windows platform dependencies (@opentui/core-win32-x64 with DLL files) as optionalDependencies, but the Nix build only started failing after the Windows desktop support was added because:

1. Before: Bun install on macOS would skip Windows optional dependencies
2. After Jan 1: Something in the build process changed that now installs ALL optional dependencies regardless of platform

Last working commit: 0b1f6a7 (2025-12-31)

Timeline:

• ✅ Dec 31, 2025: Build works on macOS
• ❌ Jan 1, 2026: Build fails after Windows desktop support + hash update