Coding agents on Windows, natively

Claude Code

Install it from PowerShell with irm https://claude.ai/install.ps1 | iex; no admin rights or Node.js needed (official setup guide). The installer puts claude.exe in %USERPROFILE%\.local\bin and may ask you to add that folder to your PATH yourself. Two more Windows details matter:

• Shell. With Git for Windows installed, Claude runs commands in Git Bash; set CLAUDE_CODE_USE_POWERSHELL_TOOL=1 to add its PowerShell tool. Without Git, PowerShell is its shell. Either works with OpenMimir.
• Permission rules. PowerShell commands follow PowerShell(...) rules, not Bash(...) ones, so a rule like Bash(git push *) needs a PowerShell(git push *) twin. Claude Code matches aliases, so PowerShell(Remove-Item *) also covers rm and del.

Codex

npm install -g @openai/codex gives you the Codex CLI on Windows. It runs commands in its own Windows sandbox: on recent Windows 11 builds it uses Microsoft's new isolation (no admin needed), and elsewhere a sandbox that an administrator sets up once. Windows 11 is the recommended base; Windows 10 works on a best-effort basis.

One thing to know: until a sandbox is chosen, Codex can read your code but every write is rejected, even with sandbox_mode = "workspace-write". Run codex once and pick one, or add this to %USERPROFILE%\.codex\config.toml:

[windows]
sandbox = "mxc"

OpenCode

This is where most people trip up: npm install -g opencode-ai still installs OpenCode 1. OpenCode 2 is npm install -g @opencode/cli, or a standalone zip from the OpenCode 2 docs (Windows x64 and ARM64). Check with opencode --version. Its background server works on Windows too: opencode service start.

Native or WSL?

Native is simplest when your projects live on the Windows drive and you use Windows tools. WSL 2 gives you a Linux toolchain and Claude Code's sandboxing, at the cost of a second file system. Agents installed inside WSL keep their history inside WSL too, so tools running on Windows don't see those sessions.

One conversation over all three

OpenMimir runs natively on Windows 10 and 11 (x64 and Arm). Install it from PowerShell, no admin rights needed:

irm https://openmimir.com/install.ps1 | iex

• It finds Claude Code, Codex and OpenCode however you installed them, including npm's .cmd shims and install folders that never made it onto your PATH, and reads their history from %USERPROFILE%.
• It uses your OpenCode background service when it runs, so its messages show up live in OpenCode, and starts its own OpenCode server otherwise.
• It sends prompts to the agents on standard input, so nothing gets mangled by Windows command-line quoting or cut off by its length limit.
• Its safety rules cover PowerShell and cmd as well as Bash: Remove-Item -Recurse, rd /s, irm ... | iex, Stop-Computer and friends wait for an on-screen approval, and voice can never approve them.
• Stopping a session stops the agent and everything it started, and closing Mimir's window or pressing Ctrl+C takes its agents down with it.
• mimir doctor tells you if something is missing, such as Codex's Windows sandbox.
• Press CtrlShiftSpace in the browser to talk.