diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index b514ca62..8b09b02e 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -1,6 +1,6 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2026-06-02 19:13:42 UTC using RuboCop version 1.87.0.
+# on 2026-06-14 16:06:06 UTC using RuboCop version 1.87.0.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
@@ -24,12 +24,17 @@ Lint/RedundantRequireStatement:
   Exclude:
     - 'lib/cucumber/core/test/location.rb'
 
-# Offense count: 1
+# Offense count: 3
 # Configuration parameters: AllowedMethods, AllowedPatterns, CountRepeatedAttributes.
 Metrics/AbcSize:
   Max: 21
 
 # Offense count: 1
+# Configuration parameters: CountComments, CountAsOne.
+Metrics/ClassLength:
+  Max: 111
+
+# Offense count: 3
 # Configuration parameters: CountComments, CountAsOne, AllowedMethods, AllowedPatterns.
 Metrics/MethodLength:
   Max: 28
diff --git a/lib/cucumber/core/test/runner.rb b/lib/cucumber/core/test/runner.rb
index 49bf98db..36dd467a 100644
--- a/lib/cucumber/core/test/runner.rb
+++ b/lib/cucumber/core/test/runner.rb
@@ -3,34 +3,51 @@
 require 'cucumber/messages/helpers/test_step_result_comparator'
 
 require_relative 'timer'
+require 'cucumber/messages'
 
 module Cucumber
   module Core
     module Test
       class Runner
-        attr_reader :event_bus, :running_test_case, :running_test_step
-        private :event_bus, :running_test_case, :running_test_step
+        include Cucumber::Messages::Helpers::TimeConversion
 
-        def initialize(event_bus)
+        attr_reader :event_bus, :running_test_case, :running_test_step, :id_generator
+        private :event_bus, :running_test_case, :running_test_step, :id_generator
+
+        def initialize(event_bus, backtrace_filter = nil, max_attempts = 1)
           @event_bus = event_bus
+          @max_attempts = max_attempts
+          @backtrace_filter = backtrace_filter
+          @id_generator = Cucumber::Messages::Helpers::IdGenerator::UUID.new
+          @current_test_case = nil
         end
 
         def test_case(test_case, &descend)
+          @attempt = @current_test_case == test_case ? @attempt + 1 : 1
+          @current_test_case = test_case
+          @current_test_case_started_id = id_generator.new_id
           @running_test_case = RunningTestCase.new
           @running_test_step = nil
           event_bus.test_case_started(test_case)
+          event_bus.envelope(create_test_case_started_message(test_case))
+
           descend.call(self)
-          result = running_test_case.result
-          result = Result::Undefined.new('The test case has no steps', Result::UnknownDuration.new, ["#{test_case.location}:in `#{test_case.name}'"]) if result.unknown?
+
+          result = calculate_test_case_result(test_case)
           event_bus.test_case_finished(test_case, result)
+          event_bus.envelope(create_test_case_finished_message(result))
           self
         end
 
         def test_step(test_step)
           @running_test_step = test_step
           event_bus.test_step_started test_step
+          event_bus.envelope(create_test_step_started_message(test_step))
+
           step_result = running_test_case.execute(test_step)
+
           event_bus.test_step_finished test_step, step_result
+          event_bus.envelope(create_test_step_finished_message(test_step, step_result))
           @running_test_step = nil
           self
         end
@@ -46,6 +63,85 @@ def done
           self
         end
 
+        def calculate_test_case_result(test_case)
+          if running_test_case.result.unknown?
+            Result::Undefined.new('The test case has no steps', Result::UnknownDuration.new, ["#{test_case.location}:in `#{test_case.name}'"])
+          else
+            running_test_case.result
+          end
+        end
+
+        def create_test_case_started_message(test_case)
+          Cucumber::Messages::Envelope.new(
+            test_case_started: Cucumber::Messages::TestCaseStarted.new(
+              id: @current_test_case_started_id,
+              test_case_id: test_case.id,
+              timestamp: time_to_timestamp(Time.now),
+              attempt: @attempt
+            )
+          )
+        end
+
+        def create_test_case_finished_message(result)
+          Cucumber::Messages::Envelope.new(
+            test_case_finished: Cucumber::Messages::TestCaseFinished.new(
+              test_case_started_id: @current_test_case_started_id,
+              timestamp: time_to_timestamp(Time.now),
+              will_be_retried: result.failed? && (@attempt < @max_attempts)
+            )
+          )
+        end
+
+        def create_test_step_started_message(test_step)
+          Cucumber::Messages::Envelope.new(
+            test_step_started: Cucumber::Messages::TestStepStarted.new(
+              test_step_id: test_step.id,
+              test_case_started_id: @current_test_case_started_id,
+              timestamp: time_to_timestamp(Time.now)
+            )
+          )
+        end
+
+        def create_test_step_finished_message(test_step, step_result)
+          result = @backtrace_filter.nil? ? step_result : step_result.with_filtered_backtrace(@backtrace_filter)
+          result_message = result.to_message
+          if result.failed? || result.pending?
+            message_element = result.failed? ? result.exception : result
+
+            result_message = Cucumber::Messages::TestStepResult.new(
+              status: result_message.status,
+              duration: result_message.duration,
+              message: create_error_message(message_element),
+              exception: create_exception_object(result, message_element)
+            )
+          end
+          Cucumber::Messages::Envelope.new(
+            test_step_finished: Cucumber::Messages::TestStepFinished.new(
+              test_step_id: test_step.id,
+              test_case_started_id: @current_test_case_started_id,
+              test_step_result: result_message,
+              timestamp: time_to_timestamp(Time.now)
+            )
+          )
+        end
+
+        def create_error_message(message_element)
+          <<~ERROR_MESSAGE
+            #{message_element.message} (#{message_element.class})
+            #{message_element.backtrace}
+          ERROR_MESSAGE
+        end
+
+        def create_exception_object(result, message_element)
+          return unless result.failed?
+
+          Cucumber::Messages::Exception.new(
+            type: message_element.class,
+            message: message_element.message,
+            stack_trace: message_element.backtrace.join("\n")
+          )
+        end
+
         class RunningTestCase
           include Cucumber::Messages::Helpers::TestStepResultComparator
 
diff --git a/spec/cucumber/core/test/runner_spec.rb b/spec/cucumber/core/test/runner_spec.rb
index 69384ff5..5f676e87 100644
--- a/spec/cucumber/core/test/runner_spec.rb
+++ b/spec/cucumber/core/test/runner_spec.rb
@@ -397,7 +397,11 @@
         it 'calls skip, rather than execute on test step of the hook' do
           expect(failing_hook).not_to receive(:execute)
 
-          allow(failing_hook).to receive(:skip).and_return(Cucumber::Core::Test::Result::Failed.new(Cucumber::Core::Test::Result::UnknownDuration.new, instance_double(StandardError, backtrace: [])))
+          allow(failing_hook).to receive(:skip).and_return(
+            Cucumber::Core::Test::Result::Failed.new(
+              Cucumber::Core::Test::Result::UnknownDuration.new, instance_double(StandardError, backtrace: [], message: nil)
+            )
+          )
           test_case.describe_to(runner)
         end
       end