follow-nix

follow-nix is a simple tool that checks your input follows and reports two things:

1. Follow candidates — inputs of your inputs that point at the same repository as one of your root inputs but are not deduplicated via follows.
2. Override warnings — existing follows where the upstream flake declared something different from what it receives in your flake.

Usage

$ follow-nix --help
usage: follow-nix [-h] [--json] [--no-overrides] [--fail-on {never,candidates,overrides,any}] [flake]

Report flake inputs that could follow a root input, and existing follows that override an upstream pin

positional arguments:
  flake                 path to the flake directory (default: .)

options:
  -h, --help            show this help message and exit
  --json                emit machine-readable JSON
  --no-overrides        skip the override check (no store/network access, candidates only)
  --fail-on {never,candidates,overrides,any}
                        exit non-zero when findings of this kind exist (default: never)
$ follow-nix /path/to/flake # or just follow-nix in a flake dir
Follow candidates:
  hydra.nixpkgs -> nixpkgs | nixpkgs-stable (upstream: NixOS/nixpkgs@nixos-25.05-small)
Override warnings:
  copyparty.nixpkgs follows nixos/nixpkgs@nixos-unstable but upstream declares nixpkgs@nixos-25.05 (upstream pins ref nixos-25.05)