## Discover Nix files

### Rule

Use `util.collectNixFiles` to discover Nix files.
Do not use `builtins.readDir` with a `.nix` suffix filter for this purpose.
Pass `util` to Nix functions that need the helper.

### Rationale

`util.collectNixFiles` centralizes recursive discovery of Nix files.
Repository Nix code uses one implementation.

## Remove Nix file suffixes with the utility

### Rule

Use `util.removeNixSuffix` to derive a Nix name from a path.
Do not call `lib.removeSuffix ".nix"` outside the utility definition.

### Rationale

The utility centralizes Nix file-name normalization.

## Use executable helpers for package commands

### Rule

Use `lib.getExe` for a package's main executable.
Use `lib.getExe'` for a package's non-main executable.
Do not build executable paths with `"${pkg}/bin/name"` when an executable helper names the target.
Use `lib.getExe' config.programs.<name>.package "tool"` when a command follows a configured package option.

### Rationale

Executable helpers select the package output that contains binaries.
They make package ownership explicit.
`lib.getExe'` prevents calls to a package's main executable when code needs another tool.

## Prefer NixOS package ownership for commands

### Rule

Use `pkgs.<name>` for Home Manager tools.
Use `config.programs.<name>.package` when a NixOS module owns the package selection.
Do not read `config.home-manager.users.<user>.programs.<name>.package` for command paths.

### Rationale

Home Manager uses the NixOS package set in this repository.
`pkgs.<name>` avoids dependency paths through the user tree under Home Manager.
Configured NixOS package options preserve package selection when a module owns the tool.