xtruder/nix-devcontainer — reverse-engineered prompt

Build me a reusable VS Code dev container setup that lets someone open almost any project in a clean, repeatable workspace using Nix. I want it to feel like a simple starter kit, not something only Nix experts can understand.

Use a small Debian based container, install and configure Nix, direnv, and the VS Code Nix Environment Selector so the tools from a project’s shell.nix are loaded automatically in the editor and terminal. Include a basic shell.nix and .envrc example, plus clear devcontainer files for both normal Docker usage and docker compose usage. It should work nicely on Linux, macOS, Windows, and Codespaces.

Please add helpful README instructions that explain how a person adds this to an existing project, how they add packages to shell.nix, how to rebuild or reload the environment, and what to do if file ownership or user id issues happen. Look up current docs online if you need to.