utils: Add ‘rosenthal-transformation-guix’.

* modules/rosenthal/utils/transformations.scm: New file.

modules/rosenthal/utils/transformations.scm

@@ -0,0 +1,61 @@
+;;; SPDX-License-Identifier: GPL-3.0-or-later
+;;; Copyright © 2025 Hilton Chain <hako@ultrarare.space>
+
+(define-module (rosenthal utils transformations)
+  #:use-module (guix channels)
+  #:use-module (guix gexp)
+  #:use-module (gnu system)
+  #:use-module (gnu services)
+  #:use-module (gnu services base)
+  #:use-module (gnu packages package-management)
+  #:export (rosenthal-transformation-guix))
+
+
+(define* (rosenthal-transformation-guix #:key (substitutes? #t)
+                                        (channel? #t)
+                                        (guix-source? #f))
+  (define %rosenthal-signing-key
+    (plain-file "rosenthal.pub" "
+(public-key
+ (ecc
+  (curve Ed25519)
+  (q #374EC58F5F2EC0412431723AF2D527AD626B049D657B5633AAAEBC694F3E33F9#)))"))
+
+  (define %rosenthal-channel
+    (channel
+      (name 'rosenthal)
+      (url "https://codeberg.org/hako/rosenthal.git")
+      (branch "trunk")
+      (introduction
+       (make-channel-introduction
+        "7677db76330121a901604dfbad19077893865f35"
+        (openpgp-fingerprint
+         "13E7 6CD6 E649 C28C 3385  4DF5 5E5A A665 6149 17F7")))))
+
+  (lambda (os)
+    (operating-system
+      (inherit os)
+      (services
+       (modify-services (operating-system-user-services os)
+         (guix-service-type
+          config => (guix-configuration
+                     (inherit config)
+                     (channels
+                      (let ((configured-channels
+                             (guix-configuration-channels config)))
+                        (if channel?
+                            (cons %rosenthal-channel
+                                  (or configured-channels %default-channels))
+                            configured-channels)))
+                     (guix
+                      (if guix-source?
+                          (guix-for-channels channels)
+                          (guix-configuration-guix config)))
+                     (authorized-keys
+                      (cons %rosenthal-signing-key
+                            (guix-configuration-authorized-keys config)))
+                     (substitute-urls
+                      `(,@(guix-configuration-substitute-urls config)
+                        ,@(if substitutes?
+                              '("https://ci.boiledscript.com")
+                              '()))))))))))