From 68cc6fa178d6598b63567564981ab389538e6998 Mon Sep 17 00:00:00 2001
From: cinereal <cinereal@riseup.net>
Date: Mon, 1 Jun 2026 21:38:02 +0200
Subject: [PATCH 1/2] document pinning nixpkgs pin for NixOS by npins from
 `system.nix`

Signed-off-by: cinereal <cinereal@riseup.net>
---
 .../guides/recipes/dependency-management.md   | 24 +++++++++++++++----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/source/guides/recipes/dependency-management.md b/source/guides/recipes/dependency-management.md
index 7c4161776..08ce4134c 100644
--- a/source/guides/recipes/dependency-management.md
+++ b/source/guides/recipes/dependency-management.md
@@ -109,11 +109,26 @@ All the imported entries will be updated, so they won't necessarily point to the
 
 ## Managing NixOS configurations
 
-NixOS relies on the `NIX_PATH` environment variable to locate `nixpkgs`, which defaults to using channels.
-To instead use a `nixpkgs` version managed by `npins`, one can manually override this environment variable on system rebuilds:
+NixOS defaults to using channels to locate `nixpkgs`.
+You can instead pin a version using `npins` from the `system.nix` entrypoint:
 
-```bash
-sudo NIX_PATH="nixos-config=configuration.nix:nixpkgs=$(nix-instantiate --raw --eval npins -A nixpkgs.outPath)" nixos-rebuild switch
+```nix
+let
+  sources = import ./npins;
+in
+import "${sources.nixpkgs}/nixos" {
+  configuration = ./configuration.nix;
+}
+```
+
+You can then disable channels in your configuration:
+
+```nix
+# configuration.nix
+{
+  # ...
+  nix.channel.enable = false;
+}
 ```
 
 To make such pinned dependencies available as [look-up paths](https://nix.dev/tutorials/nix-language.html#lookup-paths) (like `<nixpkgs>`) while using the NixOS configuration, one may use:
@@ -126,7 +141,6 @@ let
 in
 {
   # ...
-  nix.channel.enable = false;
   nix.nixPath = lib.mapAttrsToList (k: v: "${k}=${v}") sources;
 }
 ```

From 5416f1220ad37cf17216efd3e4eb6987efcd83cd Mon Sep 17 00:00:00 2001
From: cinereal <cinereal@riseup.net>
Date: Wed, 3 Jun 2026 13:47:25 +0200
Subject: [PATCH 2/2] explain npins for both new and old nixos

Signed-off-by: cinereal <cinereal@riseup.net>
---
 source/guides/recipes/dependency-management.md | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/source/guides/recipes/dependency-management.md b/source/guides/recipes/dependency-management.md
index 08ce4134c..c1fee0de2 100644
--- a/source/guides/recipes/dependency-management.md
+++ b/source/guides/recipes/dependency-management.md
@@ -110,7 +110,7 @@ All the imported entries will be updated, so they won't necessarily point to the
 ## Managing NixOS configurations
 
 NixOS defaults to using channels to locate `nixpkgs`.
-You can instead pin a version using `npins` from the `system.nix` entrypoint:
+You can instead pin a version using `npins` from the `system.nix` entrypoint (available since 26.05):
 
 ```nix
 let
@@ -121,7 +121,13 @@ import "${sources.nixpkgs}/nixos" {
 }
 ```
 
-You can then disable channels in your configuration:
+Before NixOS 26.05's `system.nix` use:
+
+```bash
+sudo NIX_PATH="nixos-config=configuration.nix:nixpkgs=$(nix-instantiate --raw --eval npins -A nixpkgs.outPath)" nixos-rebuild switch
+```
+
+If you use npins with `system.nix`, disable channels in your configuration:
 
 ```nix
 # configuration.nix