Add excluded paths

README.md

@@ -17,7 +17,9 @@ With Rails 7+, you can start a new application with propshaft using `rails new m
 
 ## Usage
 
-Propshaft makes all the assets from all the paths it's been configured with through `config.assets.paths` available for serving and will copy all of them into `public/assets` when precompiling. This is unlike Sprockets, which did not copy over assets that hadn't been explicitly included in one of the bundled assets.
+Propshaft makes all the assets from all the paths it's been configured with through `config.assets.paths` available for serving and will copy all of them into `public/assets` when precompiling. This is unlike Sprockets, which did not copy over assets that hadn't been explicitly included in one of the bundled assets. 
+
+You can however exempt directories that have been added through the `config.assets.excluded_paths`. This is useful if you're for example using `app/assets/stylesheets` exclusively as a set of inputs to a compiler like Dart Sass for Rails, and you don't want these input files to be part of the load path.
 
 These assets can be referenced through their logical path using the normal helpers like `asset_path`, `image_tag`, `javascript_include_tag`, and all the other asset helper tags. These logical references are automatically converted into digest-aware paths in production when `assets:precompile` has been run (through a JSON mapping file found in `public/assets/.manifest.json`).
 

lib/propshaft/railtie.rb

@@ -4,9 +4,10 @@
 module Propshaft
   class Railtie < ::Rails::Railtie
     config.assets = ActiveSupport::OrderedOptions.new
-    config.assets.paths       = []
-    config.assets.prefix      = "/assets"
-    config.assets.compilers   = [
+    config.assets.paths          = []
+    config.assets.excluded_paths = []
+    config.assets.prefix         = "/assets"
+    config.assets.compilers      = [
       [ "text/css", Propshaft::Compilers::CssAssetUrls ],
       [ "text/css", Propshaft::Compilers::SourceMappingUrls ],
       [ "text/javascript", Propshaft::Compilers::SourceMappingUrls ]
@@ -21,6 +22,8 @@ class Railtie < ::Rails::Railtie
       app.config.assets.paths.unshift(*paths["vendor/assets"].existent_directories)
       app.config.assets.paths.unshift(*paths["lib/assets"].existent_directories)
       app.config.assets.paths.unshift(*paths["app/assets"].existent_directories)
+
+      app.config.assets.paths = app.config.assets.paths.without(Array(app.config.assets.excluded_paths).collect(&:to_s))
     end
 
     config.after_initialize do |app|