diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..67f8702
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,33 @@
+name: CI
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+
+jobs:
+  spec:
+    name: spec (${{ matrix.ruby }})
+    runs-on: ubuntu-latest
+    continue-on-error: ${{ matrix.experimental || false }}
+    strategy:
+      fail-fast: false
+      matrix:
+        ruby:
+          - "3.1"
+          - "3.4"
+          - "jruby-9.4"
+          - "jruby-10.0"
+        include:
+          # Bleeding-edge runtime: exercised, but allowed to fail so a
+          # not-yet-released or in-flight toolchain never blocks a PR.
+          - ruby: "4.0"
+            experimental: true
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
+      - name: Run specs
+        run: bundle exec rake spec
diff --git a/.rspec b/.rspec
new file mode 100644
index 0000000..5be63fc
--- /dev/null
+++ b/.rspec
@@ -0,0 +1,2 @@
+--require spec_helper
+--format documentation
diff --git a/.rubocop.yml b/.rubocop.yml
index 29fc4b9..74b4db0 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -1,4 +1,4 @@
-require:
+plugins:
   - rubocop-rails
   - rubocop-performance
 
diff --git a/.ruby-version b/.ruby-version
index 94ff29c..7921bd0 100644
--- a/.ruby-version
+++ b/.ruby-version
@@ -1 +1 @@
-3.1.1
+3.4.8
diff --git a/README.md b/README.md
index 1ba673a..81aa004 100644
--- a/README.md
+++ b/README.md
@@ -1,8 +1,18 @@
-[![Dependency Status](https://gemnasium.com/mxenabled/mad_rubocop.svg)](https://gemnasium.com/mxenabled/mad_rubocop)
-
 # MadRubocop
 
-Custom RuboCop yml files to modify the cops enforced by RuboCop.
+[![CI](https://github.com/mxenabled/mad_rubocop/actions/workflows/ci.yml/badge.svg)](https://github.com/mxenabled/mad_rubocop/actions/workflows/ci.yml)
+
+Custom RuboCop yml files to modify the cops enforced by RuboCop, shared across projects.
+
+Built on RuboCop `~> 1.88`, rubocop-rails `~> 2.35`, and rubocop-performance `~> 1.26`. Requires Ruby `>= 3.1`.
+
+## What's in the box
+
+This gem ships configuration only — no Ruby code. Consumers inherit three files:
+
+- `.rubocop.yml` — the entry point. Loads the `rubocop-rails` and `rubocop-performance` plugins, inherits the two files below, and sets `AllCops` defaults (`NewCops: disable`, so cops added in a RuboCop upgrade stay off until explicitly enabled here).
+- `lib/disabled_cops.yml` — cops turned off, either as permanent house style or because the codebase isn't ready for them.
+- `lib/modified_cops.yml` — cops kept on but configured to a non-default style (e.g. `hash_rockets`, `double_quotes`, outdented access modifiers).
 
 ## Installation
 
@@ -27,15 +37,28 @@ inherit_gem:
   mad_rubocop: .rubocop.yml
 ```
 
-NOTE: The `Exlude` setting on cops that only ignore certain files or directories cannot be set by MadRubocop.
+NOTE: The `Exclude` setting on cops that only ignore certain files or directories cannot be set by MadRubocop.
 
 
 ## Development
 
 After checking out the repo, run `bin/setup` to install dependencies.
 
+Run the test suite with `bundle exec rake spec`. The specs validate the shipped configuration against the installed RuboCop — they confirm the config loads, the rubocop-rails and rubocop-performance plugins are present, and every referenced cop still exists (catching cops that a RuboCop upgrade renames or removes).
+
 To install this gem onto your local machine, run `bundle exec rake install`. To release a new version, update the version number in `version.rb`, and then run `bundle exec rake release`, which will create a git tag for the version, push git commits and tags, and push the `.gem` file to [rubygems.org](https://rubygems.org).
 
+### Upgrading RuboCop
+
+Keeping the pinned RuboCop (and its plugins) current is the main maintenance task. The workflow:
+
+1. Bump the version constraints for `rubocop`, `rubocop-rails`, and/or `rubocop-performance` in `mad_rubocop.gemspec`.
+2. Run `bundle update rubocop rubocop-rails rubocop-performance`.
+3. Run `bundle exec rake spec`. The suite fails if the config references a cop that the new RuboCop **renamed or removed** — the failure message names the offending cop.
+4. For each failure, update the cop name in `lib/disabled_cops.yml` / `lib/modified_cops.yml` (or drop it if the cop no longer exists).
+5. Because `NewCops` is disabled, cops **added** in the upgrade are off by default. Review `rubocop --show-cops` (or the release notes) and add any you want to disable/configure.
+6. Bump `MadRubocop::VERSION` in `version.rb`, note the change, and release.
+
 ## Contributing
 
 Bug reports and pull requests are welcome on GitHub at https://github.com/mxenabled/mad_rubocop.
diff --git a/Rakefile b/Rakefile
index 2995527..b7e9ed5 100644
--- a/Rakefile
+++ b/Rakefile
@@ -1 +1,6 @@
 require "bundler/gem_tasks"
+require "rspec/core/rake_task"
+
+RSpec::Core::RakeTask.new(:spec)
+
+task :default => :spec
diff --git a/lib/disabled_cops.yml b/lib/disabled_cops.yml
index 78710c9..903517a 100644
--- a/lib/disabled_cops.yml
+++ b/lib/disabled_cops.yml
@@ -113,7 +113,7 @@ Naming/HeredocDelimiterCase:
   Enabled: false
 Naming/MemoizedInstanceVariableName:
   Enabled: false
-Naming/PredicateName:
+Naming/PredicatePrefix:
   Enabled: false
 Naming/MethodParameterName:
   Enabled: false
diff --git a/lib/mad_rubocop/version.rb b/lib/mad_rubocop/version.rb
index 67e0fbb..0338c8a 100644
--- a/lib/mad_rubocop/version.rb
+++ b/lib/mad_rubocop/version.rb
@@ -1,3 +1,3 @@
 module MadRubocop
-  VERSION = "4.0.0"
+  VERSION = "4.2.0.pre1"
 end
diff --git a/mad_rubocop.gemspec b/mad_rubocop.gemspec
index baea7d5..e9176ac 100644
--- a/mad_rubocop.gemspec
+++ b/mad_rubocop.gemspec
@@ -20,9 +20,12 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
 
-  spec.add_dependency "rubocop", "~> 1.32.0"
-  spec.add_dependency "rubocop-performance", "~> 1.14.3"
-  spec.add_dependency "rubocop-rails", "~> 2.15.2"
+  spec.required_ruby_version = ">= 3.1"
+
+  spec.add_dependency "rubocop", "~> 1.88.0"
+  spec.add_dependency "rubocop-performance", "~> 1.26.1"
+  spec.add_dependency "rubocop-rails", "~> 2.35.5"
   spec.add_development_dependency "bundler", "~> 2.0"
   spec.add_development_dependency "rake"
+  spec.add_development_dependency "rspec", "~> 3.0"
 end
diff --git a/spec/fixtures/sample.rb b/spec/fixtures/sample.rb
new file mode 100644
index 0000000..8a0160c
--- /dev/null
+++ b/spec/fixtures/sample.rb
@@ -0,0 +1,7 @@
+# A tiny fixture used to exercise the gem's RuboCop configuration end-to-end.
+# It exists only so the CLI has something to inspect; offenses are irrelevant.
+module Sample
+  def self.greeting
+    "hello"
+  end
+end
diff --git a/spec/mad_rubocop/config_spec.rb b/spec/mad_rubocop/config_spec.rb
new file mode 100644
index 0000000..81fb46e
--- /dev/null
+++ b/spec/mad_rubocop/config_spec.rb
@@ -0,0 +1,76 @@
+require "spec_helper"
+require "yaml"
+require "stringio"
+require "rubocop"
+
+# These specs treat the gem's YAML as the unit under test. Because mad_rubocop
+# ships nothing but configuration, the most valuable guarantees are that the
+# config loads under the pinned RuboCop, that every cop it references still
+# exists, and that RuboCop raises no obsolete/removed-cop warnings when it runs.
+# A green suite here is what catches upgrades that rename a cop (e.g. the
+# Naming/PredicateName -> Naming/PredicatePrefix rename in RuboCop 1.88).
+RSpec.describe "MadRubocop configuration" do
+  ROOT = File.expand_path("../..", __dir__)
+  CONFIG_FILE = File.join(ROOT, ".rubocop.yml")
+  COP_CONFIG_FILES = {
+    "disabled_cops.yml" => File.join(ROOT, "lib", "disabled_cops.yml"),
+    "modified_cops.yml" => File.join(ROOT, "lib", "modified_cops.yml"),
+  }.freeze
+
+  # Loading the config also loads the rubocop-rails / rubocop-performance
+  # plugins declared under `plugins:`, which registers their cops globally.
+  before(:all) do
+    RuboCop::ConfigLoader.load_file(CONFIG_FILE)
+  end
+
+  def self.cop_names_in(file)
+    YAML.safe_load(File.read(file)).keys.select { |key| key.include?("/") }
+  end
+
+  it "loads the top-level config without raising" do
+    expect { RuboCop::ConfigLoader.load_file(CONFIG_FILE) }.not_to raise_error
+  end
+
+  it "loads the rubocop-rails and rubocop-performance plugin cops" do
+    departments = RuboCop::Cop::Registry.global.departments.map(&:to_s)
+
+    expect(departments).to include("Rails", "Performance")
+  end
+
+  describe "every configured cop is recognized by the installed RuboCop" do
+    COP_CONFIG_FILES.each do |label, file|
+      context label do
+        cop_names_in(file).each do |cop_name|
+          it "recognizes #{cop_name}" do
+            cop = RuboCop::Cop::Registry.global.find_by_cop_name(cop_name)
+
+            expect(cop).not_to(
+              be_nil,
+              "#{cop_name} is not a known cop — it may have been renamed, " \
+              "removed, or moved to a plugin that is no longer loaded",
+            )
+          end
+        end
+      end
+    end
+  end
+
+  it "runs against a fixture without emitting obsolete/removed-cop warnings" do
+    fixture = File.join(ROOT, "spec", "fixtures", "sample.rb")
+
+    captured = StringIO.new
+    original_stderr = $stderr
+    $stderr = captured
+    begin
+      RuboCop::CLI.new.run(
+        ["--config", CONFIG_FILE, "--force-exclusion", "--no-color", fixture],
+      )
+    ensure
+      $stderr = original_stderr
+    end
+
+    expect(captured.string).not_to match(
+      /obsolete|has been (removed|renamed|extracted)|unrecognized cop/i,
+    )
+  end
+end
diff --git a/spec/mad_rubocop/version_spec.rb b/spec/mad_rubocop/version_spec.rb
new file mode 100644
index 0000000..271a4af
--- /dev/null
+++ b/spec/mad_rubocop/version_spec.rb
@@ -0,0 +1,14 @@
+require "spec_helper"
+
+RSpec.describe MadRubocop do
+  it "has a semantic version number" do
+    expect(MadRubocop::VERSION).to match(/\A\d+\.\d+\.\d+\z/)
+  end
+
+  it "matches the version declared in the gemspec" do
+    gemspec_path = File.expand_path("../../mad_rubocop.gemspec", __dir__)
+    gemspec = Gem::Specification.load(gemspec_path)
+
+    expect(gemspec.version.to_s).to eq(MadRubocop::VERSION)
+  end
+end
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
new file mode 100644
index 0000000..0a2fb2c
--- /dev/null
+++ b/spec/spec_helper.rb
@@ -0,0 +1,15 @@
+require "mad_rubocop"
+
+RSpec.configure do |config|
+  config.expect_with :rspec do |expectations|
+    expectations.include_chain_clauses_in_custom_matcher_descriptions = true
+  end
+
+  config.mock_with :rspec do |mocks|
+    mocks.verify_partial_doubles = true
+  end
+
+  config.disable_monkey_patching!
+  config.order = :random
+  Kernel.srand config.seed
+end