Migrate the asset pipeline from Sprockets to Propshaft

.github/workflows/a11y.yml

@@ -43,6 +43,8 @@ jobs:
       run: npm ci --omit=dev
     - name: Set up Database
       run: bundle exec rails db:setup
+    - name: Build CSS
+      run: bundle exec rails dartsass:build
     - name: Create separate Chrome data directories
       run: |
         mkdir -p /tmp/chrome-data-rspec

.github/workflows/cucumber.yml

@@ -50,6 +50,8 @@ jobs:
         chrome-version: stable
     - name: Setup Database
       run: bundle exec rails db:setup
+    - name: Build CSS
+      run: bundle exec rails dartsass:build
     - name: Create Chrome data directory
       run: mkdir -p /tmp/chrome-data-cucumber
     - name: Run non-JavaScript Cucumber tests

.github/workflows/rspec.yml

@@ -47,6 +47,8 @@ jobs:
     - name: Setup Database
       run: |
         bundle exec rails db:test:prepare
+    - name: Build CSS
+      run: bundle exec rails dartsass:build
     - name: Create Chrome data directory
       run: mkdir -p /tmp/chrome-data-rspec
     - name: Run RSpec Tests

.gitignore

@@ -66,6 +66,10 @@ node_modules/
 /public/packs-test
 /public/assets
 
+# Dart Sass build output (app/assets/builds/application.css)
+/app/assets/builds/*
+!/app/assets/builds/.keep
+
 # Ignore yarn files
 /yarn-error.log
 yarn-debug.log*

Gemfile

@@ -81,8 +81,9 @@ gem 'hypershield'
 gem 'good_job', '~> 4.19'
 
 #### Frontend related tools
-# The original asset pipeline for Rails [https://github.com/rails/sprockets-rails]
-gem 'sprockets-rails'
+# Rails 8's default asset pipeline: digests and serves what's on disk, and does
+# no compiling of its own [https://github.com/rails/propshaft]
+gem 'propshaft'
 
 # Use JavaScript with ESM import maps [https://github.com/rails/importmap-rails]
 gem 'importmap-rails'
@@ -91,19 +92,15 @@ gem 'importmap-rails'
 gem 'turbo-rails'
 
 gem 'bootstrap', '~> 5.3.8'
-# Compiles the SCSS in app/assets/stylesheets with Dart Sass (the only Sass
-# implementation still maintained) via Sprockets. Replaces sassc-rails, which
-# was deprecated along with its LibSass backend. Everything else about the
-# pipeline is unchanged: same stylesheet_link_tag, same manifest.js.
-#
-# `sassc` itself is still resolved as a transitive dependency (of both
-# sassc-embedded and font-awesome-sass), but only as an API shim — LibSass no
-# longer compiles anything.
+# Compiles app/assets/stylesheets/application.scss to app/assets/builds with
+# Dart Sass (the only Sass implementation still maintained), which Propshaft
+# then digests and serves. Replaces sassc-rails, deprecated along with its
+# LibSass backend.
 #
 # Bootstrap 5.3 still uses `@import`, which Dart Sass deprecated; those warnings
 # are silenced in config/initializers/dartsass.rb. Bootstrap 6 moves to `@use`,
 # at which point the silencing can go away.
-gem 'dartsass-sprockets', '~> 3.2'
+gem 'dartsass-rails', '~> 0.5'
 
 # Font Awesome for icons
 gem 'font-awesome-sass'

Gemfile.lock

@@ -85,14 +85,10 @@ GEM
       uri (>= 0.13.1)
     addressable (2.9.0)
       public_suffix (>= 2.0.2, < 8.0)
-    annotaterb (4.24.0)
+    annotaterb (4.23.0)
       activerecord (>= 6.0.0)
       activesupport (>= 6.0.0)
-    anonymous_loader (0.1.3)
-      version_gem (~> 1.1, >= 1.1.14)
     ast (2.4.3)
-    auth-sanitizer (0.2.3)
-      version_gem (~> 1.1, >= 1.1.14)
     axe-core-api (4.12.0)
       dumb_delegator
     axe-core-cucumber (4.12.0)
@@ -139,7 +135,7 @@ GEM
       bigdecimal
       rexml
     crass (1.0.7)
-    csv (3.3.6)
+    csv (3.3.5)
     cucumber (11.1.1)
       base64 (~> 0.2)
       builder (~> 3.2)
@@ -169,12 +165,9 @@ GEM
       cucumber (>= 7, < 12)
       railties (>= 6.1, < 9)
     cucumber-tag-expressions (8.1.0)
-    dartsass-sprockets (3.2.1)
-      railties (>= 4.0.0)
-      sassc-embedded (~> 1.80.1)
-      sprockets (> 3.0)
-      sprockets-rails
-      tilt
+    dartsass-rails (0.5.1)
+      railties (>= 6.0.0)
+      sass-embedded (~> 1.63)
     database_cleaner-active_record (2.2.2)
       activerecord (>= 5.a)
       database_cleaner-core (~> 2.0)
@@ -191,9 +184,9 @@ GEM
       railties (>= 6.1)
     drb (2.2.3)
     dumb_delegator (1.1.0)
-    erb (6.0.7)
+    erb (6.0.6)
     erubi (1.13.1)
-    et-orbi (1.4.1)
+    et-orbi (1.4.0)
       tzinfo
     factory_bot (6.5.6)
       activesupport (>= 6.1.0)
@@ -254,7 +247,7 @@ GEM
     google-protobuf (4.35.1-x86_64-linux-gnu)
       bigdecimal
       rake (~> 13.3)
-    guard (2.20.2)
+    guard (2.20.1)
       formatador (>= 0.2.4)
       listen (>= 2.7, < 4.0)
       logger (~> 1.6)
@@ -273,7 +266,7 @@ GEM
     hashdiff (1.2.1)
     hashie (5.1.0)
       logger
-    http-cookie (1.1.6)
+    http-cookie (1.1.0)
       domain_name (~> 0.5)
     httparty (0.24.2)
       csv
@@ -296,7 +289,7 @@ GEM
     jbuilder (2.15.1)
       actionview (>= 7.0.0)
       activesupport (>= 7.0.0)
-    json (2.21.2)
+    json (2.21.1)
     json_schemer (2.5.0)
       bigdecimal
       hana (~> 1.3)
@@ -342,7 +335,7 @@ GEM
       net-smtp
     marcel (1.2.1)
     matrix (0.4.3)
-    mcp (0.25.0)
+    mcp (0.22.0)
       json_schemer (>= 2.4)
     memoist3 (1.0.0)
     method_source (1.1.0)
@@ -351,9 +344,9 @@ GEM
     minitest (6.0.6)
       drb (~> 2.0)
       prism (~> 1.5)
-    msgpack (1.8.4)
+    msgpack (1.8.3)
     multi_test (1.1.0)
-    multi_xml (0.9.1)
+    multi_xml (0.8.1)
       bigdecimal (>= 3.1, < 5)
     nenv (0.3.0)
     net-http (0.9.1)
@@ -384,16 +377,14 @@ GEM
     notiffany (0.1.3)
       nenv (~> 0.1)
       shellany (~> 0.0)
-    oauth2 (2.0.25)
-      anonymous_loader (~> 0.1, >= 0.1.3)
-      auth-sanitizer (~> 0.2, >= 0.2.3)
+    oauth2 (2.0.18)
       faraday (>= 0.17.3, < 4.0)
       jwt (>= 1.0, < 4.0)
       logger (~> 1.2)
       multi_xml (~> 0.5)
       rack (>= 1.2, < 4)
-      snaky_hash (~> 2.0, >= 2.0.7)
-      version_gem (~> 1.1, >= 1.1.14)
+      snaky_hash (~> 2.0, >= 2.0.3)
+      version_gem (~> 1.1, >= 1.1.9)
     omniauth (2.1.4)
       hashie (>= 3.4.6)
       logger
@@ -410,7 +401,7 @@ GEM
       omniauth (~> 2.0)
     ostruct (0.6.3)
     parallel (2.1.0)
-    parser (3.3.12.0)
+    parser (3.3.11.1)
       ast (~> 2.4.1)
       racc
     pg (1.6.3)
@@ -423,6 +414,10 @@ GEM
       prettyprint
     prettyprint (0.2.0)
     prism (1.9.0)
+    propshaft (1.3.2)
+      actionpack (>= 7.0.0)
+      activesupport (>= 7.0.0)
+      rack
     pry (0.16.0)
       coderay (~> 1.1)
       method_source (~> 1.0)
@@ -486,7 +481,7 @@ GEM
     rb-fsevent (0.11.2)
     rb-inotify (0.11.1)
       ffi (~> 1.0)
-    rbs (4.1.2)
+    rbs (4.1.0)
       logger
       prism (>= 1.6.0)
       tsort
@@ -574,8 +569,6 @@ GEM
       google-protobuf (~> 4.31)
     sassc (2.4.0)
       ffi (~> 1.9)
-    sassc-embedded (1.80.9)
-      sass-embedded (~> 1.80)
     securerandom (0.4.1)
     selenium-webdriver (4.46.0)
       base64 (~> 0.2)
@@ -595,17 +588,9 @@ GEM
       activesupport (>= 7.2)
     simplecov (1.0.3)
     simpleidn (0.2.3)
-    snaky_hash (2.0.7)
+    snaky_hash (2.0.3)
       hashie (>= 0.1.0, < 6)
-      version_gem (~> 1.1, >= 1.1.14)
-    sprockets (4.2.2)
-      concurrent-ruby (~> 1.0)
-      logger
-      rack (>= 2.2.4, < 4)
-    sprockets-rails (3.5.2)
-      actionpack (>= 6.1)
-      activesupport (>= 6.1)
-      sprockets (>= 3.0.0)
+      version_gem (>= 1.1.8, < 3)
     stimulus-rails (1.3.4)
       railties (>= 6.0.0)
     strong_migrations (2.8.0)
@@ -618,7 +603,6 @@ GEM
       memoist3 (~> 1.0.0)
       win32ole
     thor (1.5.0)
-    tilt (2.8.0)
     timecop (0.9.11)
     timeout (0.6.1)
     tsort (0.2.0)
@@ -627,14 +611,14 @@ GEM
       railties (>= 7.1.0)
     tzinfo (2.0.6)
       concurrent-ruby (~> 1.0)
-    tzinfo-data (1.2026.3)
+    tzinfo-data (1.2026.1)
       tzinfo (>= 1.0.0)
     unicode-display_width (3.2.0)
       unicode-emoji (~> 4.1)
     unicode-emoji (4.2.0)
     uri (1.1.1)
     useragent (0.16.11)
-    version_gem (1.1.15)
+    version_gem (1.1.9)
     web-console (4.3.0)
       actionview (>= 8.0.0)
       bindex (>= 0.4.0)
@@ -651,7 +635,7 @@ GEM
     win32ole (1.9.3)
     xpath (3.2.0)
       nokogiri (~> 1.8)
-    zeitwerk (2.8.3)
+    zeitwerk (2.8.2)
 
 PLATFORMS
   aarch64-linux
@@ -674,7 +658,7 @@ DEPENDENCIES
   capybara-screenshot
   codeclimate-test-reporter
   cucumber-rails
-  dartsass-sprockets (~> 3.2)
+  dartsass-rails (~> 0.5)
   database_cleaner-active_record
   debug
   dotenv-rails
@@ -699,6 +683,7 @@ DEPENDENCIES
   omniauth-rails_csrf_protection
   ostruct
   pg
+  propshaft
   puma (>= 6.0)
   rack_session_access
   rails (~> 8.1.3)
@@ -714,7 +699,6 @@ DEPENDENCIES
   sentry-ruby
   shoulda-matchers (~> 8.0)
   simplecov (~> 1.0.3)
-  sprockets-rails
   stimulus-rails
   strong_migrations
   timecop

Procfile.dev

@@ -1 +1,2 @@
 web: bundle exec rails s -p ${PORT:-3000}
+css: bundle exec rails dartsass:watch

app/assets/stylesheets/application.scss

@@ -112,6 +112,13 @@ $escaped-characters: (
   (")", "%29"),
 );
 
+// font-awesome-sass emits `font-path(...)` when Sprockets' Sass helpers are
+// available and falls back to `#{$fa-font-path}/#{$file}` otherwise. Dart Sass
+// runs as a plain CLI here, so the fallback is what we get — point it at the
+// logical path of the gem's webfonts (its assets/fonts directory is on the
+// Propshaft load path) and let Propshaft rewrite the url() to a digested one.
+$fa-font-path: "font-awesome";
+
 @import "bootstrap";
 
 // DataTables' Bootstrap 5 theme, imported straight out of node_modules (see

bin/setup

@@ -29,6 +29,12 @@ FileUtils.chdir APP_ROOT do
   puts "\n== Preparing database =="
   system! "bin/rails db:prepare"
 
+  # application.css is a build artifact now, so a fresh checkout has none and
+  # the first page render would raise Propshaft::MissingAssetError. `make dev`
+  # keeps it up to date after this via the css process in Procfile.dev.
+  puts "\n== Building CSS =="
+  system! "bin/rails dartsass:build"
+
   puts "\n== Removing old logs and tempfiles =="
   system! "bin/rails log:clear tmp:clear"
 

config/environments/development.rb

@@ -68,14 +68,7 @@
   # Highlight code that enqueued background job in logs.
   config.active_job.verbose_enqueue_logs = true
 
-  # Suppress logger output for asset requests.
-  config.assets.quiet = false
-  config.assets.debug = true
-  # TODO: WARNING -- As of April 2026 / Rails 7.2 / sprockets + importmaps
-  # This must be set to true or JS does not seem to load in development.
-  config.assets.digest = true
   config.cache_classes = false
-  config.assets.compile = true
 
   # Raises error for missing translations.
   # config.i18n.raise_on_missing_translations = true

config/environments/production.rb

@@ -23,12 +23,6 @@
   # Disable serving static files from `public/`, relying on NGINX/Apache to do so instead.
   # config.public_file_server.enabled = false
 
-  # Compress CSS using a preprocessor.
-  # config.assets.css_compressor = :sass
-
-  # Do not fall back to assets pipeline if a precompiled asset is missed.
-  config.assets.compile = false
-
   # Enable serving of images, stylesheets, and JavaScripts from an asset server.
   # config.asset_host = "http://assets.example.com"