Manually register the Play routes compiler toolchain

MODULE.bazel

@@ -20,6 +20,8 @@ bazel_dep(name = "stardoc", version = "0.7.1")
 
 register_toolchains(
     "//:repository_default_toolchain_21_definition",
+    "//play-routes-toolchain:play-routes-3",
+    "//play-routes-toolchain:play-routes-2-13",
     "//scala:zinc_2_13",
     "//scala:zinc_3",
 )

play-routes-toolchain/BUILD.bazel

@@ -1,8 +1,21 @@
 load("@bazel_skylib//:bzl_library.bzl", "bzl_library")
+load("@bazel_skylib//rules:common_settings.bzl", "string_flag", "string_setting")
 load(":create-toolchain.bzl", "create_play_routes_toolchain")
 
 toolchain_type(name = "toolchain_type")
 
+string_setting(
+    name = "original-play-routes-toolchain",
+    build_setting_default = "",
+    visibility = ["//visibility:public"],
+)
+
+string_flag(
+    name = "play-routes-toolchain",
+    build_setting_default = "play-routes-3",
+    visibility = ["//visibility:public"],
+)
+
 create_play_routes_toolchain(
     name = "play-routes-3",
     play_routes_compiler = "//play-routes-compiler-cli:play-routes-compiler-cli-3",

play-routes-toolchain/create-toolchain.bzl

@@ -12,7 +12,7 @@ def create_play_routes_toolchain(name, play_routes_compiler):
     native.config_setting(
         name = config_setting_name,
         flag_values = {
-            "@rules_play_routes_toolchain//:play-routes-toolchain": name,
+            "//play-routes-toolchain": name,
         },
     )
 

play-routes-toolchain/transitions.bzl

@@ -1,8 +1,8 @@
 # This approach of incoming transition, store original values, outgoing
 # transition, reset to original values is inspired by what the rules_go
 # folks are doing.
-toolchain_setting_key = "@rules_play_routes_toolchain//:play-routes-toolchain"
-original_toolchain_setting_key = "@rules_play_routes_toolchain//:original-play-routes-toolchain"
+toolchain_setting_key = "//play-routes-toolchain"
+original_toolchain_setting_key = "//play-routes-toolchain:original-play-routes-toolchain"
 
 def _play_routes_toolchain_transition_impl(settings, attr):
     """Update the rules_play_routes toolchain to the overridden value. Store