diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 006d608..8d8701f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -12,7 +12,10 @@ jobs:
   tests:
     runs-on: ubuntu-latest
     name: Tests - Ruby ${{ matrix.ruby }}
-    strategy: { matrix: { ruby: [3.2, 3.3, 3.4, 4.0] } }
+    strategy:
+      fail-fast: false
+      matrix:
+        ruby: ["4.0"]
 
     steps:
       - uses: actions/checkout@v4
@@ -31,7 +34,7 @@ jobs:
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: 3.4
+          ruby-version: "4.0"
           bundler-cache: true
       - name: bundle install
         run: bundle install
@@ -48,7 +51,7 @@ jobs:
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: 3.4
+          ruby-version: "4.0"
           bundler-cache: true
       - name: bundle install
         run: bundle install
diff --git a/.standard.yml b/.standard.yml
index 0ed8183..f9293dc 100644
--- a/.standard.yml
+++ b/.standard.yml
@@ -1,3 +1,3 @@
 # For available configuration options, see:
 #   https://github.com/standardrb/standard
-ruby_version: 3.1
+ruby_version: 4.0
diff --git a/CLAUDE.md b/CLAUDE.md
index 143672d..a850ba8 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -131,7 +131,7 @@ Integration tests run against a minimal Rails app in `test/dummy/`:
 
 ## Requirements
 
-- Ruby >= 3.2.0
+- Ruby >= 4.0
 - Rails >= 8.0
 - Bundler
 
diff --git a/Gemfile.lock b/Gemfile.lock
index fb4767f..97b6414 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -7,31 +7,31 @@ PATH
 GEM
   remote: https://rubygems.org/
   specs:
-    action_text-trix (2.1.15)
+    action_text-trix (2.1.19)
       railties
-    actioncable (8.1.1)
-      actionpack (= 8.1.1)
-      activesupport (= 8.1.1)
+    actioncable (8.1.3)
+      actionpack (= 8.1.3)
+      activesupport (= 8.1.3)
       nio4r (~> 2.0)
       websocket-driver (>= 0.6.1)
       zeitwerk (~> 2.6)
-    actionmailbox (8.1.1)
-      actionpack (= 8.1.1)
-      activejob (= 8.1.1)
-      activerecord (= 8.1.1)
-      activestorage (= 8.1.1)
-      activesupport (= 8.1.1)
+    actionmailbox (8.1.3)
+      actionpack (= 8.1.3)
+      activejob (= 8.1.3)
+      activerecord (= 8.1.3)
+      activestorage (= 8.1.3)
+      activesupport (= 8.1.3)
       mail (>= 2.8.0)
-    actionmailer (8.1.1)
-      actionpack (= 8.1.1)
-      actionview (= 8.1.1)
-      activejob (= 8.1.1)
-      activesupport (= 8.1.1)
+    actionmailer (8.1.3)
+      actionpack (= 8.1.3)
+      actionview (= 8.1.3)
+      activejob (= 8.1.3)
+      activesupport (= 8.1.3)
       mail (>= 2.8.0)
       rails-dom-testing (~> 2.2)
-    actionpack (8.1.1)
-      actionview (= 8.1.1)
-      activesupport (= 8.1.1)
+    actionpack (8.1.3)
+      actionview (= 8.1.3)
+      activesupport (= 8.1.3)
       nokogiri (>= 1.8.5)
       rack (>= 2.2.4)
       rack-session (>= 1.0.1)
@@ -39,36 +39,36 @@ GEM
       rails-dom-testing (~> 2.2)
       rails-html-sanitizer (~> 1.6)
       useragent (~> 0.16)
-    actiontext (8.1.1)
+    actiontext (8.1.3)
       action_text-trix (~> 2.1.15)
-      actionpack (= 8.1.1)
-      activerecord (= 8.1.1)
-      activestorage (= 8.1.1)
-      activesupport (= 8.1.1)
+      actionpack (= 8.1.3)
+      activerecord (= 8.1.3)
+      activestorage (= 8.1.3)
+      activesupport (= 8.1.3)
       globalid (>= 0.6.0)
       nokogiri (>= 1.8.5)
-    actionview (8.1.1)
-      activesupport (= 8.1.1)
+    actionview (8.1.3)
+      activesupport (= 8.1.3)
       builder (~> 3.1)
       erubi (~> 1.11)
       rails-dom-testing (~> 2.2)
       rails-html-sanitizer (~> 1.6)
-    activejob (8.1.1)
-      activesupport (= 8.1.1)
+    activejob (8.1.3)
+      activesupport (= 8.1.3)
       globalid (>= 0.3.6)
-    activemodel (8.1.1)
-      activesupport (= 8.1.1)
-    activerecord (8.1.1)
-      activemodel (= 8.1.1)
-      activesupport (= 8.1.1)
+    activemodel (8.1.3)
+      activesupport (= 8.1.3)
+    activerecord (8.1.3)
+      activemodel (= 8.1.3)
+      activesupport (= 8.1.3)
       timeout (>= 0.4.0)
-    activestorage (8.1.1)
-      actionpack (= 8.1.1)
-      activejob (= 8.1.1)
-      activerecord (= 8.1.1)
-      activesupport (= 8.1.1)
+    activestorage (8.1.3)
+      actionpack (= 8.1.3)
+      activejob (= 8.1.3)
+      activerecord (= 8.1.3)
+      activesupport (= 8.1.3)
       marcel (~> 1.0)
-    activesupport (8.1.1)
+    activesupport (8.1.3)
       base64
       bigdecimal
       concurrent-ruby (~> 1.0, >= 1.3.1)
@@ -83,45 +83,45 @@ GEM
       uri (>= 0.13.1)
     ast (2.4.3)
     base64 (0.3.0)
-    bigdecimal (3.3.1)
-    brakeman (7.1.1)
+    bigdecimal (4.1.2)
+    brakeman (8.0.5)
       racc
     builder (3.3.0)
-    concurrent-ruby (1.3.5)
-    connection_pool (2.5.4)
-    crass (1.0.6)
-    date (3.5.0)
-    docile (1.4.1)
+    concurrent-ruby (1.3.8)
+    connection_pool (3.0.2)
+    crass (1.0.7)
+    date (3.5.1)
     drb (2.2.3)
-    erb (5.1.3)
+    erb (6.0.6)
     erubi (1.13.1)
-    globalid (1.3.0)
+    globalid (1.4.0)
       activesupport (>= 6.1)
-    i18n (1.14.7)
+    i18n (1.15.2)
       concurrent-ruby (~> 1.0)
-    io-console (0.8.1)
-    irb (1.15.3)
+    io-console (0.8.2)
+    irb (1.18.0)
       pp (>= 0.6.0)
+      prism (>= 1.3.0)
       rdoc (>= 4.0.0)
       reline (>= 0.4.2)
-    json (2.15.2)
-    language_server-protocol (3.17.0.5)
+    json (2.21.1)
+    language_server-protocol (3.17.0.6)
     lint_roller (1.1.0)
     logger (1.7.0)
-    loofah (2.24.1)
+    loofah (2.25.2)
       crass (~> 1.0.2)
       nokogiri (>= 1.12.0)
-    mail (2.9.0)
+    mail (2.9.1)
       logger
       mini_mime (>= 0.1.1)
       net-imap
       net-pop
       net-smtp
-    marcel (1.1.0)
+    marcel (1.2.1)
     mini_mime (1.1.5)
     mini_portile2 (2.8.9)
     minitest (5.27.0)
-    net-imap (0.5.12)
+    net-imap (0.6.4.1)
       date
       net-protocol
     net-pop (0.1.2)
@@ -150,50 +150,47 @@ GEM
       racc (~> 1.4)
     nokogiri (1.19.4-x86_64-linux-musl)
       racc (~> 1.4)
-    parallel (1.27.0)
-    parser (3.3.10.0)
+    parallel (2.1.0)
+    parser (3.3.12.0)
       ast (~> 2.4.1)
       racc
-    pp (0.6.3)
+    pp (0.6.4)
       prettyprint
     prettyprint (0.2.0)
-    prism (1.6.0)
-    psych (5.2.6)
-      date
-      stringio
+    prism (1.9.0)
     racc (1.8.1)
-    rack (3.2.4)
-    rack-session (2.1.1)
+    rack (3.2.6)
+    rack-session (2.1.2)
       base64 (>= 0.1.0)
       rack (>= 3.0.0)
     rack-test (2.2.0)
       rack (>= 1.3)
-    rackup (2.2.1)
+    rackup (2.3.1)
       rack (>= 3)
-    rails (8.1.1)
-      actioncable (= 8.1.1)
-      actionmailbox (= 8.1.1)
-      actionmailer (= 8.1.1)
-      actionpack (= 8.1.1)
-      actiontext (= 8.1.1)
-      actionview (= 8.1.1)
-      activejob (= 8.1.1)
-      activemodel (= 8.1.1)
-      activerecord (= 8.1.1)
-      activestorage (= 8.1.1)
-      activesupport (= 8.1.1)
+    rails (8.1.3)
+      actioncable (= 8.1.3)
+      actionmailbox (= 8.1.3)
+      actionmailer (= 8.1.3)
+      actionpack (= 8.1.3)
+      actiontext (= 8.1.3)
+      actionview (= 8.1.3)
+      activejob (= 8.1.3)
+      activemodel (= 8.1.3)
+      activerecord (= 8.1.3)
+      activestorage (= 8.1.3)
+      activesupport (= 8.1.3)
       bundler (>= 1.15.0)
-      railties (= 8.1.1)
+      railties (= 8.1.3)
     rails-dom-testing (2.3.0)
       activesupport (>= 5.0.0)
       minitest
       nokogiri (>= 1.6)
-    rails-html-sanitizer (1.6.2)
-      loofah (~> 2.21)
+    rails-html-sanitizer (1.7.1)
+      loofah (~> 2.25, >= 2.25.2)
       nokogiri (>= 1.15.7, != 1.16.7, != 1.16.6, != 1.16.5, != 1.16.4, != 1.16.3, != 1.16.2, != 1.16.1, != 1.16.0.rc1, != 1.16.0)
-    railties (8.1.1)
-      actionpack (= 8.1.1)
-      activesupport (= 8.1.1)
+    railties (8.1.3)
+      actionpack (= 8.1.3)
+      activesupport (= 8.1.3)
       irb (~> 1.13)
       rackup (>= 1.0.0)
       rake (>= 12.2)
@@ -201,40 +198,40 @@ GEM
       tsort (>= 0.2)
       zeitwerk (~> 2.6)
     rainbow (3.1.1)
-    rake (13.3.1)
-    rdoc (6.15.1)
+    rake (13.4.2)
+    rbs (4.0.3)
+      logger
+      prism (>= 1.6.0)
+      tsort
+    rdoc (8.0.0)
       erb
-      psych (>= 4.0.0)
+      prism (>= 1.6.0)
+      rbs (>= 4.0.0)
       tsort
-    regexp_parser (2.11.3)
-    reline (0.6.2)
+    regexp_parser (2.12.0)
+    reline (0.6.3)
       io-console (~> 0.5)
-    rubocop (1.75.5)
+    rubocop (1.88.2)
       json (~> 2.3)
       language_server-protocol (~> 3.17.0.2)
       lint_roller (~> 1.1.0)
-      parallel (~> 1.10)
+      parallel (>= 1.10)
       parser (>= 3.3.0.2)
       rainbow (>= 2.2.2, < 4.0)
       regexp_parser (>= 2.9.3, < 3.0)
-      rubocop-ast (>= 1.44.0, < 2.0)
+      rubocop-ast (>= 1.49.0, < 2.0)
       ruby-progressbar (~> 1.7)
       unicode-display_width (>= 2.4.0, < 4.0)
-    rubocop-ast (1.47.1)
+    rubocop-ast (1.50.0)
       parser (>= 3.3.7.2)
-      prism (~> 1.4)
-    rubocop-performance (1.25.0)
+      prism (~> 1.7)
+    rubocop-performance (1.26.1)
       lint_roller (~> 1.1)
       rubocop (>= 1.75.0, < 2.0)
-      rubocop-ast (>= 1.38.0, < 2.0)
+      rubocop-ast (>= 1.47.1, < 2.0)
     ruby-progressbar (1.13.0)
     securerandom (0.4.1)
-    simplecov (0.22.0)
-      docile (~> 1.1)
-      simplecov-html (~> 0.11)
-      simplecov_json_formatter (~> 0.1)
-    simplecov-html (0.13.2)
-    simplecov_json_formatter (0.1.4)
+    simplecov (1.0.2)
     sqlite3 (2.9.5)
       mini_portile2 (~> 2.8.0)
     sqlite3 (2.9.5-aarch64-linux-gnu)
@@ -247,21 +244,20 @@ GEM
     sqlite3 (2.9.5-x86_64-darwin)
     sqlite3 (2.9.5-x86_64-linux-gnu)
     sqlite3 (2.9.5-x86_64-linux-musl)
-    standard (1.49.0)
+    standard (1.56.0)
       language_server-protocol (~> 3.17.0.2)
       lint_roller (~> 1.0)
-      rubocop (~> 1.75.2)
+      rubocop (~> 1.88.0)
       standard-custom (~> 1.0.0)
       standard-performance (~> 1.8)
     standard-custom (1.0.2)
       lint_roller (~> 1.0)
       rubocop (~> 1.50)
-    standard-performance (1.8.0)
+    standard-performance (1.9.0)
       lint_roller (~> 1.1)
-      rubocop-performance (~> 1.25.0)
-    stringio (3.1.7)
-    thor (1.4.0)
-    timeout (0.4.4)
+      rubocop-performance (~> 1.26.0)
+    thor (1.5.0)
+    timeout (0.6.1)
     tsort (0.2.0)
     tzinfo (2.0.6)
       concurrent-ruby (~> 1.0)
@@ -270,11 +266,11 @@ GEM
     unicode-emoji (4.2.0)
     uri (1.1.1)
     useragent (0.16.11)
-    websocket-driver (0.8.0)
+    websocket-driver (0.8.2)
       base64
       websocket-extensions (>= 0.1.0)
     websocket-extensions (0.1.5)
-    zeitwerk (2.7.3)
+    zeitwerk (2.8.2)
 
 PLATFORMS
   aarch64-linux-gnu
diff --git a/README.md b/README.md
index 0ebf1f8..6f1e18f 100644
--- a/README.md
+++ b/README.md
@@ -29,7 +29,7 @@ Bunko (文庫) in Japanese means a small personal library or book collection - a
 
 ## Requirements
 
-- Ruby >= 3.2.0
+- Ruby >= 4.0
 - Rails >= 8.0
 
 ## Quick Start
@@ -728,7 +728,7 @@ test/
 ### CI Testing
 
 GitHub Actions runs the full test suite on every PR:
-- Ruby versions: 3.2, 3.3, 3.4, 3.5
+- Ruby versions: 4.0
 - All tests with fresh generated code
 - StandardRB linting
 - Brakeman security scans (Rails 8.0.x and 8.1.x)
diff --git a/ROADMAP.md b/ROADMAP.md
index 91affad..dc87ad7 100644
--- a/ROADMAP.md
+++ b/ROADMAP.md
@@ -462,7 +462,7 @@ New developer can:
 
 **Compatibility:**
 - Works with Rails 8.0+ and follows Rails EOL maintenance policy
-- Works with Ruby 3.2, 3.3, 3.4 and follows Ruby EOL maintenance policy
+- Works with Ruby 4.0+ and follows Ruby EOL maintenance policy
 - Works with PostgreSQL, SQLite, MySQL
 - Test coverage > 90%
 - All Standard linter checks pass
diff --git a/bunko.gemspec b/bunko.gemspec
index 36cbf86..7c3e06b 100644
--- a/bunko.gemspec
+++ b/bunko.gemspec
@@ -12,7 +12,7 @@ Gem::Specification.new do |spec|
   spec.description = "Bunko provides a lightweight CMS structure for Rails based on a 'one model, infinite collections' philosophy. Create multiple content collections (blog, docs, changelog) without duplicate code or migrations."
   spec.homepage = "https://github.com/kanejamison/bunko"
   spec.license = "MIT"
-  spec.required_ruby_version = ">= 3.2"
+  spec.required_ruby_version = ">= 4.0"
 
   spec.metadata["homepage_uri"] = spec.homepage
   spec.metadata["changelog_uri"] = "https://github.com/kanejamison/bunko/blob/main/CHANGELOG.md"