diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7112931..188cc47 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ Entries before 1.6.6 were reconstructed from `git log` and RubyGems release date
 
 ### Changed
 
+- `Ruby2html::Component#render_in` accepts Rails' keyword options (`locals:`), as Rails main (8.2) passes them and deprecates `render_in` without options.
 - On CRuby, a C extension that fails to load now prints one warning with the reason (`ruby2html: C extension not loaded (...); using the pure-Ruby renderer`) instead of silently rendering about 3x slower. JRuby/TruffleRuby and `RUBY2HTML_DISABLE_EXT=1` stay silent.
 
 ## [2.0.0] - 2026-10-31
diff --git a/gemfiles/rails_common.rb b/gemfiles/rails_common.rb
index 91927f2..c8909de 100644
--- a/gemfiles/rails_common.rb
+++ b/gemfiles/rails_common.rb
@@ -12,7 +12,13 @@
 gem 'rake-compiler', '~> 1.2', require: false
 
 group :test do
-  gem 'rspec-rails', '>= 6.1'
+  # Rails main pairs with rspec-rails main: releases trail Rails main changes (e.g. Rails main
+  # freezes default_url_options, which rspec-rails 8.0.x still writes to).
+  if ENV['RAILS_VERSION'] == 'edge'
+    gem 'rspec-rails', github: 'rspec/rspec-rails', branch: 'main'
+  else
+    gem 'rspec-rails', '>= 6.1'
+  end
   gem 'capybara', '~> 3.40'
   gem 'faker', '>= 3.4'
   gem 'benchmark-ips'
diff --git a/lib/gem/ruby2html/component.rb b/lib/gem/ruby2html/component.rb
index de3ecd3..1c2a6e3 100644
--- a/lib/gem/ruby2html/component.rb
+++ b/lib/gem/ruby2html/component.rb
@@ -64,8 +64,10 @@ def __r2h_capacity
     # The buffer currently written to (RailsComponents swap it to capture blocks).
     attr_accessor :current_output
 
-    # Rails' entry point: `render component` in views and controllers.
-    def render_in(view_context, &block)
+    # Rails' entry point: `render component` in views and controllers. Rails 8.2+ passes
+    # `locals:` (render_in without options is deprecated there); a component takes its data
+    # through #initialize, so options are accepted and ignored.
+    def render_in(view_context, **_options, &block)
       buffer = String.new(capacity: self.class.__r2h_capacity, encoding: Encoding::UTF_8)
       content = block && -> { plain(view_context.capture(self, &block)) }
       render_into(buffer, view_context, content)
diff --git a/spec/gem/rails/component_spec.rb b/spec/gem/rails/component_spec.rb
index 9066746..88c6c7f 100644
--- a/spec/gem/rails/component_spec.rb
+++ b/spec/gem/rails/component_spec.rb
@@ -50,9 +50,9 @@ def view_template
   it 'never builds a String for nested components' do
     child = CardComponent.new(title: 'x')
     expect(child).not_to receive(:render_in)
-    parent = Class.new(described_class) do
+    parent = stub_const('ParentComponent', Class.new(described_class) do
       define_method(:view_template) { render child }
-    end
+    end)
     view.render(parent.new)
   end
 
@@ -71,26 +71,27 @@ def view_template
   end
 
   it 'supports #call and an overridden #template as the entry point' do
-    via_call = Class.new(described_class) { def call = p('call') }
-    via_template = Class.new(described_class) { def template = p('template') }
+    via_call = stub_const('ViaCallComponent', Class.new(described_class) { def call = p('call') })
+    via_template = stub_const('ViaTemplateComponent', Class.new(described_class) { def template = p('template') })
     expect(view.render(via_call.new)).to eq('<p>call</p>')
     expect(view.render(via_template.new)).to eq('<p>template</p>')
   end
 
   it 'raises a clear error without an entry point, and helpers outside a render' do
-    expect { view.render(Class.new(described_class).new) }.to raise_error(NotImplementedError, /view_template/)
+    stub_const('EmptyComponent', Class.new(described_class))
+    expect { view.render(EmptyComponent.new) }.to raise_error(NotImplementedError, /view_template/)
     expect { CardComponent.new(title: 'x').helpers }.to raise_error(Ruby2html::Error)
   end
 
   it 'restores its state when the template raises, so it can be rendered again' do
-    flaky = Class.new(described_class) do
+    flaky = stub_const('FlakyComponent', Class.new(described_class) do
       attr_accessor :fail
 
       def view_template
         h1 'ok'
         raise 'boom' if fail
       end
-    end.new
+    end).new
     flaky.fail = true
     expect { view.render(flaky) }.to raise_error('boom')
     expect(flaky.current_output).to be_nil
@@ -99,7 +100,7 @@ def view_template
   end
 
   it 'renders two components interleaved in fibers without crosstalk' do
-    yielding = Class.new(described_class) do
+    yielding = stub_const('YieldingComponent', Class.new(described_class) do
       def initialize(name) = @name = name
 
       def view_template
@@ -107,7 +108,7 @@ def view_template
         Fiber.yield
         p @name
       end
-    end
+    end)
     fibers = %w[a b].map { |name| Fiber.new { view.render(yielding.new(name)) } }
     fibers.each(&:resume)
     expect(fibers.reverse.map(&:resume)).to eq(['<h1>b</h1><p>b</p>', '<h1>a</h1><p>a</p>'])