Automatic Follows

flake-file can use flake-edit follow to add and remove follows declarations whenever flake.nix is generated.

This is an alternative to the flake.lock flattening hook. Both approaches reduce duplicate transitive inputs, but they store the result in different places. Generally, choose one rather than enabling both.

{ inputs, ... }:
{
  imports = [ inputs.flake-file.flakeModules.auto-follow ];
}

Alternatively, enable the underlying option directly with flake-file.auto-follow.enable = true.

write-flake updates flake.lock, runs flake-edit follow, and updates the lock again. The generated-file check runs the same follow operation on a temporary copy, so nix flake check also detects missing or stale automatic follows.

Automatic follows require pkgs.flake-edit version 0.3.5 or newer. Enabling the feature with an older or missing package produces an evaluation error identifying the required version.

Automatic follows or lock flattening?

	Automatic follows	Lock flattening hook
Source of truth	follows declarations in flake.nix	Rewritten relationships in flake.lock
Visibility	Relationships are visible when reviewing flake.nix	Keeps flake.nix free of generated follows
Configuration	Supports per-nested-input opt-outs	Configured for the whole lock file
Writes	Updates both flake.nix and flake.lock	Rewrites only flake.lock after generation
Best fit	Explicit, reviewable Nix-native follows	Existing lock-flattening workflows or minimal generated flakes

Use automatic follows when you want deduplication represented as ordinary flake declarations. Use the lock hook when you want deduplication to remain an implementation detail of the generated lock file.

Opting out an input

When automatic follows are enabled, flake-edit manages nested follows declarations by default. Exclude a particular nested input when it should not be followed automatically:

{
  flake-file.inputs.crane.inputs.nixpkgs.autoFollow = false;
}

An exclusion cannot also configure follows: one requests no automatic follow while the other requests an explicit follow. flake-file reports that conflicting configuration when automatic follows are enabled.