devenvlisted

# devenv Conventions for [devenv](https://devenv.sh/) development environments. The first rule is `/anvil:env`'s read-before-write rule, and it binds here too: anything whose vocabulary lives in someone else's release notes gets read, never recalled. - **File split.** `devenv.nix` is the environment. `devenv.yaml` is inputs. `devenv.lock` is the pin. `.envrc` runs `eval "$(devenv direnvrc)"` then `use devenv`, so direnv activates on `cd`. - **Interpreter pinning.** An exact interpreter needs the `nixpkgs-python` input, never whatever CPython nixpkgs happens to ship. - **Unfree toolchains.** `allowUnfree` is mandatory for CUDA. Neither this nor the pinning rule is guessable from option names. - **devenv's Claude Code integration** is configured by the owner inside their environment (`claude.code.enable`) and generates hooks, commands, and MCP config from there. Never bake it or its pieces into a generated environment. - **The foundry boundary.** foundry scaffolds an application. anvil defines the environment the application is built in. A repo can want both. They write different files.