diff --git a/ruby/lib/ci/queue/redis/build_record.rb b/ruby/lib/ci/queue/redis/build_record.rb
index cb45a755..3c23de95 100644
--- a/ruby/lib/ci/queue/redis/build_record.rb
+++ b/ruby/lib/ci/queue/redis/build_record.rb
@@ -57,12 +57,13 @@ def record_warning(type, attributes)
         end
 
         def record_error(id, payload, stats: nil)
-          acknowledged, _ = redis.pipelined do |pipeline|
-            @queue.acknowledge(id, error: payload, pipeline: pipeline)
-            record_stats(stats, pipeline: pipeline)
-          end
+          acknowledged = @queue.acknowledge(id, error: payload)
 
-          @queue.increment_test_failed if acknowledged == 1
+          if acknowledged
+            # if another worker already acknowledged the test, we don't need to update the global stats or increment the test failed count
+            record_stats(stats)
+            @queue.increment_test_failed
+          end
           nil
         end
 
diff --git a/ruby/lib/minitest/queue/runner.rb b/ruby/lib/minitest/queue/runner.rb
index ef50ada3..8515ca71 100644
--- a/ruby/lib/minitest/queue/runner.rb
+++ b/ruby/lib/minitest/queue/runner.rb
@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 require 'optparse'
 require 'json'
+require 'fileutils'
 require 'minitest/queue'
 require 'ci/queue'
 require 'digest/md5'
@@ -242,16 +243,16 @@ def bisect_command
           puts
 
           File.write('log/test_order.log', failing_order.to_a.map(&:id).join("\n"))
-          
+
           bisect_test_details = failing_order.to_a.map do |test|
             source_location = test.source_location
             file_path = source_location&.first || 'unknown'
             line_number = source_location&.last || -1
             "#{test.id} #{file_path}:#{line_number}"
           end
-          
+
           File.write('log/bisect_test_details.log', bisect_test_details.join("\n"))
-          
+
           exit! 0
         end
       end
@@ -336,8 +337,22 @@ def display_warnings(build)
         warnings = build.pop_warnings.map do |type, attributes|
           attributes.merge(type: type)
         end.compact
-        File.open(queue_config.warnings_file, 'w') do |f|
-          JSON.dump(warnings, f)
+
+        return if warnings.empty?
+
+        begin
+          # Ensure directory exists
+          dir = File.dirname(queue_config.warnings_file)
+          FileUtils.mkdir_p(dir) unless File.directory?(dir)
+
+          # Write each warning as a separate JSON line (JSONL format)
+          File.open(queue_config.warnings_file, 'a') do |f|
+            warnings.each do |warning|
+              f.puts(JSON.dump(warning))
+            end
+          end
+        rescue => error
+          STDERR.puts "Failed to write warnings: #{error.message}"
         end
       end
 
diff --git a/ruby/test/integration/minitest_redis_test.rb b/ruby/test/integration/minitest_redis_test.rb
index dbb74d9f..2a24438a 100644
--- a/ruby/test/integration/minitest_redis_test.rb
+++ b/ruby/test/integration/minitest_redis_test.rb
@@ -89,7 +89,7 @@ def test_lost_test_with_heartbeat_monitor
         assert_empty err
         result = normalize(out.lines[1].strip)
         assert_equal "Ran 1 tests, 0 assertions, 0 failures, 0 errors, 0 skips, 0 requeues in X.XXs (aggregated)", result
-        warnings = JSON.parse(warnings_file.read)
+        warnings = warnings_file.read.lines.map { |line| JSON.parse(line) }
         assert_equal 1, warnings.size
       end
     end
@@ -927,7 +927,7 @@ def test_redis_reporter
         end
 
         warnings_file.rewind
-        content = JSON.parse(warnings_file.read)
+        content = warnings_file.read.lines.map { |line| JSON.parse(line) }
         assert_equal 1, content.size
         assert_equal "RESERVED_LOST_TEST", content[0]["type"]
         assert_equal "Atest#test_bar", content[0]["test"]