diff --git a/usercase-test-coderl/kafka_producer_stateful_test.go b/usercase-test-coderl/kafka_producer_stateful_test.go
new file mode 100644
--- /dev/null
+++ b/usercase-test-coderl/kafka_producer_stateful_test.go
@@ -0,0 +1,494 @@
+package usercase_test_coderl
+
+import (
+	"fmt"
+	"os"
+	"reflect"
+	"runtime"
+	"sort"
+	"strings"
+	"testing"
+	"unsafe"
+
+	"github.com/8treenet/freedom/infra/kafka"
+	"github.com/IBM/sarama"
+)
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+func TestKafkaProducerStartNewMsgAndPublishSession(t *testing.T) {
+
+
+
+
+	impl := closeableProducer(t)
+	mustNoError(t, impl.Close())
+
+	broker := newProducerBroker(t, "orders")
+	defer broker.Close()
+	defer impl.Close()
+
+	cfg := sarama.NewConfig()
+	cfg.Version = sarama.V2_1_0_0
+	cfg.Producer.RequiredAcks = sarama.WaitForLocal
+	cfg.Producer.Return.Errors = false
+	cfg.Producer.Return.Successes = false
+	if cfg.Producer.Return.Errors != false {
+		t.Fatalf("fresh cfg Return.Errors = %v, want false", cfg.Producer.Return.Errors)
+	}
+	if cfg.Producer.Return.Successes != false {
+		t.Fatalf("fresh cfg Return.Successes = %v, want false", cfg.Producer.Return.Successes)
+	}
+
+	producer := kafka.GetProducer()
+	producer.Start([]string{broker.Addr()}, cfg)
+	if cfg.Producer.Return.Errors != true {
+		t.Fatalf("after Start Return.Errors = %v, want true", cfg.Producer.Return.Errors)
+	}
+	if cfg.Producer.Return.Successes != true {
+		t.Fatalf("after Start Return.Successes = %v, want true", cfg.Producer.Return.Successes)
+	}
+	mustNoError(t, producer.Restart())
+
+	msg := producer.NewMsg("orders", []byte("paid"))
+
+	if msg == nil {
+		t.Fatal("NewMsg returned nil")
+	}
+	if msg.GetMessageKey() != "" {
+		t.Fatalf("fresh msg key = %q, want empty string", msg.GetMessageKey())
+	}
+
+	if len(msg.GetHeader()) != 0 {
+		t.Fatalf("fresh msg headers = %#v, want no headers", msg.GetHeader())
+	}
+
+	headerReturn := msg.SetMessageKey("order-1").
+		SetHeader(map[string]interface{}{"x-request-id": "r1"}).
+		SetHeader(map[string]interface{}{"attempt": 2})
+
+	if headerReturn == nil {
+		t.Fatal("SetHeader chain returned nil")
+	}
+	msg = headerReturn
+	if msg.GetMessageKey() != "order-1" {
+		t.Fatalf("after SetMessageKey key = %q, want %q", msg.GetMessageKey(), "order-1")
+	}
+	if got := fmt.Sprint(msg.GetHeader()["x-request-id"]); got != "r1" {
+		t.Fatalf("header x-request-id = %q, want %q", got, "r1")
+	}
+	if got := fmt.Sprint(msg.GetHeader()["attempt"]); got != "2" {
+		t.Fatalf("header attempt = %q, want %q", got, "2")
+	}
+
+	mustNoError(t, msg.Publish())
+	sent := onlyProducedRecord(t, broker, "orders")
+	if sent.topic != "orders" {
+		t.Fatalf("produced topic = %q, want %q", sent.topic, "orders")
+	}
+
+	if sent.partition < 0 {
+		t.Fatalf("produced partition = %d, want a valid non-negative partition", sent.partition)
+	}
+	if sent.key != "order-1" {
+		t.Fatalf("produced key = %q, want %q", sent.key, "order-1")
+	}
+	if sent.value != "paid" {
+		t.Fatalf("produced value = %q, want %q", sent.value, "paid")
+	}
+	if !reflect.DeepEqual(sent.headers, map[string]string{"attempt": "2", "x-request-id": "r1"}) {
+		t.Fatalf("produced headers = %#v, want %#v", sent.headers, map[string]string{"attempt": "2", "x-request-id": "r1"})
+	}
+	if msg.GetExecution() != nil {
+		t.Fatalf("after successful Publish execution = %v, want nil", msg.GetExecution())
+	}
+}
+
+func TestKafkaProducerGeneratedMessageKeySession(t *testing.T) {
+
+
+
+
+	impl := closeableProducer(t)
+	mustNoError(t, impl.Close())
+
+	broker := newProducerBroker(t, "orders")
+	defer broker.Close()
+	defer impl.Close()
+
+	cfg := sarama.NewConfig()
+	cfg.Version = sarama.V2_1_0_0
+	kafka.GetProducer().Start([]string{broker.Addr()}, cfg)
+	mustNoError(t, kafka.GetProducer().Restart())
+
+	msg := kafka.GetProducer().NewMsg("orders", []byte("paid"))
+	if msg.GetMessageKey() != "" {
+		t.Fatalf("fresh generated-key msg key = %q, want empty string", msg.GetMessageKey())
+	}
+	mustNoError(t, msg.Publish())
+
+	sent := onlyProducedRecord(t, broker, "orders")
+
+	generated := sent.key
+	if len(generated) != 32 {
+		t.Fatalf("generated key length = %d, want 32", len(generated))
+	}
+	if strings.Contains(generated, "-") != false {
+		t.Fatalf("generated key contains dash = %v, want false", strings.Contains(generated, "-"))
+	}
+	if generated != strings.ToUpper(generated) {
+		t.Fatalf("generated key = %q, want uppercase", generated)
+	}
+	if sent.value != "paid" {
+		t.Fatalf("produced generated-key value = %q, want %q", sent.value, "paid")
+	}
+}
+
+func TestKafkaProducerPublishBeforeInitializedReturnsSpecificError(t *testing.T) {
+
+
+
+
+	impl := closeableProducer(t)
+	mustNoError(t, impl.Close())
+
+	msg := kafka.GetProducer().NewMsg("orders", []byte("paid"))
+	err := msg.Publish()
+	if err == nil {
+		t.Fatal("Publish before initialized error = nil, want producer is not initialized")
+	}
+	if err.Error() != "producer is not initialized" {
+		t.Fatalf("Publish before initialized error = %q, want %q", err.Error(), "producer is not initialized")
+	}
+	if msg.GetExecution() == nil {
+		t.Fatal("GetExecution after failed Publish = nil, want producer is not initialized error")
+	}
+	if msg.GetExecution().Error() != "producer is not initialized" {
+		t.Fatalf("GetExecution after failed Publish = %q, want %q", msg.GetExecution().Error(), "producer is not initialized")
+	}
+}
+
+func TestKafkaMessagesKeepIndependentState(t *testing.T) {
+
+
+
+
+	a := kafka.GetProducer().NewMsg("orders", []byte("paid"))
+	b := kafka.GetProducer().NewMsg("orders", []byte("refunded"))
+
+	a.SetMessageKey("order-1").SetHeader(map[string]interface{}{"x-request-id": "r1"})
+	if a.GetMessageKey() != "order-1" {
+		t.Fatalf("message a key = %q, want %q", a.GetMessageKey(), "order-1")
+	}
+	if got := fmt.Sprint(a.GetHeader()["x-request-id"]); got != "r1" {
+		t.Fatalf("message a header x-request-id = %q, want %q", got, "r1")
+	}
+	if b.GetMessageKey() != "" {
+		t.Fatalf("message b key = %q, want empty string", b.GetMessageKey())
+	}
+
+	if len(b.GetHeader()) != 0 {
+		t.Fatalf("message b headers = %#v, want no headers", b.GetHeader())
+	}
+
+	b.SetMessageKey("order-2").SetHeader(map[string]interface{}{"x-request-id": "r2", "attempt": 1})
+	if a.GetMessageKey() != "order-1" {
+		t.Fatalf("message a key after mutating b = %q, want %q", a.GetMessageKey(), "order-1")
+	}
+	if fmt.Sprint(a.GetHeader()["x-request-id"]) != "r1" {
+		t.Fatalf("message a x-request-id after mutating b = %q, want %q", fmt.Sprint(a.GetHeader()["x-request-id"]), "r1")
+	}
+	if b.GetMessageKey() != "order-2" {
+		t.Fatalf("message b key = %q, want %q", b.GetMessageKey(), "order-2")
+	}
+	if fmt.Sprint(b.GetHeader()["x-request-id"]) != "r2" {
+		t.Fatalf("message b x-request-id = %q, want %q", fmt.Sprint(b.GetHeader()["x-request-id"]), "r2")
+	}
+	if fmt.Sprint(b.GetHeader()["attempt"]) != "1" {
+		t.Fatalf("message b attempt = %q, want %q", fmt.Sprint(b.GetHeader()["attempt"]), "1")
+	}
+}
+
+func TestKafkaProducerCloseIsIdempotent(t *testing.T) {
+
+
+
+
+	impl := closeableProducer(t)
+	mustNoError(t, impl.Close())
+	mustNoError(t, impl.Close())
+}
+
+func TestKafkaProducerCloseReleasesResourcesAcrossCycles(t *testing.T) {
+
+
+
+
+	impl := closeableProducer(t)
+	mustNoError(t, impl.Close())
+
+	broker := newProducerBroker(t, "orders")
+	defer broker.Close()
+	defer impl.Close()
+
+	runtime.GC()
+	baseFDs := countFDs(t)
+	baseGoroutines := runtime.NumGoroutine()
+
+	for i := 0; i < 120; i++ {
+		cfg := sarama.NewConfig()
+		cfg.Version = sarama.V2_1_0_0
+		kafka.GetProducer().Start([]string{broker.Addr()}, cfg)
+		mustNoError(t, kafka.GetProducer().Restart())
+		msg := kafka.GetProducer().NewMsg("orders", []byte("paid")).SetMessageKey(fmt.Sprintf("order-%d", i))
+		mustNoError(t, msg.Publish())
+		mustNoError(t, impl.Close())
+	}
+
+	runtime.GC()
+	afterFDs := countFDs(t)
+	afterGoroutines := runtime.NumGoroutine()
+
+	if afterFDs > baseFDs+30 {
+		t.Fatalf("fd count after 120 producer cycles = %d, want <= %d", afterFDs, baseFDs+30)
+	}
+
+	if afterGoroutines > baseGoroutines+30 {
+		t.Fatalf("goroutines after 120 producer cycles = %d, want <= %d", afterGoroutines, baseGoroutines+30)
+	}
+}
+
+func TestZZZKafkaProducerMiddlewareOrderStopAndExecution(t *testing.T) {
+
+
+
+
+	impl := closeableProducer(t)
+	mustNoError(t, impl.Close())
+
+	broker := newProducerBroker(t, "orders")
+	defer broker.Close()
+	defer impl.Close()
+
+	cfg := sarama.NewConfig()
+	cfg.Version = sarama.V2_1_0_0
+	kafka.GetProducer().Start([]string{broker.Addr()}, cfg)
+	mustNoError(t, kafka.GetProducer().Restart())
+
+	var events []string
+	kafka.InstallMiddleware(
+		func(msg *kafka.Msg) {
+			events = append(events, "first-before:"+msg.GetMessageKey())
+			if msg.IsStopped() != false {
+				t.Fatalf("first middleware IsStopped = %v, want false", msg.IsStopped())
+			}
+			msg.Next()
+			if msg.GetExecution() != nil {
+				t.Fatalf("first middleware GetExecution after Next = %v, want nil", msg.GetExecution())
+			}
+			events = append(events, "first-after")
+		},
+		func(msg *kafka.Msg) {
+			events = append(events, "second-before:"+fmt.Sprint(len(msg.GetHeader())))
+			msg.Next()
+			events = append(events, "second-after")
+		},
+	)
+
+	msg := kafka.GetProducer().NewMsg("orders", []byte("paid")).
+		SetMessageKey("order-1").
+		SetHeader(map[string]interface{}{"x-request-id": "r1"})
+	mustNoError(t, msg.Publish())
+	if !reflect.DeepEqual(events, []string{"first-before:order-1", "second-before:1", "second-after", "first-after"}) {
+		t.Fatalf("middleware events = %#v, want %#v", events, []string{"first-before:order-1", "second-before:1", "second-after", "first-after"})
+	}
+	if msg.IsStopped() != false {
+		t.Fatalf("published middleware msg IsStopped = %v, want false", msg.IsStopped())
+	}
+	if msg.GetExecution() != nil {
+		t.Fatalf("published middleware msg GetExecution = %v, want nil", msg.GetExecution())
+	}
+	if countProduceRequests(broker) != 1 {
+		t.Fatalf("produce requests after continued middleware = %d, want 1", countProduceRequests(broker))
+	}
+
+	var stopEvents []string
+	kafka.InstallMiddleware(func(msg *kafka.Msg) {
+		stopEvents = append(stopEvents, "stop-before")
+		msg.Stop()
+		stopEvents = append(stopEvents, fmt.Sprintf("stopped:%v", msg.IsStopped()))
+	})
+
+	stopped := kafka.GetProducer().NewMsg("orders", []byte("blocked")).SetMessageKey("order-stop")
+	if err := stopped.Publish(); err != nil {
+		t.Fatalf("stopped Publish error = %v, want nil", err)
+	}
+	if !reflect.DeepEqual(stopEvents, []string{"stop-before", "stopped:true"}) {
+		t.Fatalf("stop middleware events = %#v, want %#v", stopEvents, []string{"stop-before", "stopped:true"})
+	}
+	if stopped.IsStopped() != true {
+		t.Fatalf("stopped msg IsStopped = %v, want true", stopped.IsStopped())
+	}
+	if stopped.GetExecution() != nil {
+		t.Fatalf("stopped msg GetExecution = %v, want nil", stopped.GetExecution())
+	}
+	if countProduceRequests(broker) != 1 {
+		t.Fatalf("produce requests after stopped middleware = %d, want 1", countProduceRequests(broker))
+	}
+}
+
+type producedRecord struct {
+	topic     string
+	partition int32
+	key       string
+	value     string
+	headers   map[string]string
+}
+
+func closeableProducer(t *testing.T) *kafka.ProducerImpl {
+	t.Helper()
+	impl, ok := kafka.GetProducer().(*kafka.ProducerImpl)
+	if !ok {
+		t.Fatalf("GetProducer concrete type = %T, want *kafka.ProducerImpl", kafka.GetProducer())
+	}
+	return impl
+}
+
+func newProducerBroker(t *testing.T, topic string) *sarama.MockBroker {
+	t.Helper()
+	broker := sarama.NewMockBroker(t, 1)
+	broker.SetHandlerByMap(map[string]sarama.MockResponse{
+		"ApiVersionsRequest": sarama.NewMockApiVersionsResponse(t),
+		"MetadataRequest": sarama.NewMockMetadataResponse(t).
+			SetBroker(broker.Addr(), broker.BrokerID()).
+			SetLeader(topic, 0, broker.BrokerID()),
+		"ProduceRequest": sarama.NewMockProduceResponse(t).
+			SetVersion(7).
+			SetError(topic, 0, sarama.ErrNoError),
+	})
+	return broker
+}
+
+func onlyProducedRecord(t *testing.T, broker *sarama.MockBroker, topic string) producedRecord {
+	t.Helper()
+	records := producedRecords(t, broker)
+	var matches []producedRecord
+	for _, record := range records {
+		if record.topic == topic {
+			matches = append(matches, record)
+		}
+	}
+	if len(matches) != 1 {
+		t.Fatalf("produced records for %q = %d (%#v), want 1", topic, len(matches), matches)
+	}
+	return matches[0]
+}
+
+func countProduceRequests(broker *sarama.MockBroker) int {
+	count := 0
+	for _, exchange := range broker.History() {
+		if _, ok := exchange.Request.(*sarama.ProduceRequest); ok {
+			count++
+		}
+	}
+	return count
+}
+
+func producedRecords(t *testing.T, broker *sarama.MockBroker) []producedRecord {
+	t.Helper()
+	var out []producedRecord
+	for _, exchange := range broker.History() {
+		req, ok := exchange.Request.(*sarama.ProduceRequest)
+		if !ok {
+			continue
+		}
+		for topic, partitions := range produceRequestRecords(req) {
+			for partition, records := range partitions {
+				if records.RecordBatch != nil {
+					for _, record := range records.RecordBatch.Records {
+						out = append(out, producedRecord{
+							topic:     topic,
+							partition: partition,
+							key:       string(record.Key),
+							value:     string(record.Value),
+							headers:   recordHeaders(record.Headers),
+						})
+					}
+					continue
+				}
+				if records.MsgSet != nil {
+					for _, block := range records.MsgSet.Messages {
+						for _, msgBlock := range block.Messages() {
+							out = append(out, producedRecord{
+								topic:     topic,
+								partition: partition,
+								key:       string(msgBlock.Msg.Key),
+								value:     string(msgBlock.Msg.Value),
+								headers:   map[string]string{},
+							})
+						}
+					}
+				}
+			}
+		}
+	}
+	sort.Slice(out, func(i, j int) bool {
+		if out[i].topic != out[j].topic {
+			return out[i].topic < out[j].topic
+		}
+		if out[i].partition != out[j].partition {
+			return out[i].partition < out[j].partition
+		}
+		return out[i].key < out[j].key
+	})
+	return out
+}
+
+func produceRequestRecords(req *sarama.ProduceRequest) map[string]map[int32]sarama.Records {
+	value := reflect.ValueOf(req).Elem().FieldByName("records")
+	return reflect.NewAt(value.Type(), unsafe.Pointer(value.UnsafeAddr())).
+		Elem().
+		Interface().(map[string]map[int32]sarama.Records)
+}
+
+func recordHeaders(headers []*sarama.RecordHeader) map[string]string {
+	out := make(map[string]string, len(headers))
+	for _, header := range headers {
+		out[string(header.Key)] = string(header.Value)
+	}
+	return out
+}
+
+func countFDs(t *testing.T) int {
+	t.Helper()
+	entries, err := os.ReadDir("/proc/self/fd")
+	if err != nil {
+		t.Fatalf("read /proc/self/fd: %v", err)
+	}
+	return len(entries)
+}
+
+func mustNoError(t *testing.T, err error) {
+	t.Helper()
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+}
diff --git a/mimo_test_command.sh b/mimo_test_command.sh
new file mode 100755
--- /dev/null
+++ b/mimo_test_command.sh
@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+
+
+
+
+export NODE_OPTIONS="${NODE_OPTIONS:-} --max-old-space-size=4096"
+export MAVEN_OPTS="${MAVEN_OPTS:-} -Xmx3g -XX:+UseG1GC"
+export GRADLE_OPTS="${GRADLE_OPTS:-} -Xmx3g -XX:+UseG1GC"
+export TEST_JVM_OPTS="${TEST_JVM_OPTS:-} -Xmx3g"
+set -e
+cd /workspace/repo
+set -euo pipefail
+
+cd /workspace/repo
+
+export GOPROXY=off
+export GOSUMDB=off
+export GOTOOLCHAIN=local
+exec go test -v -count=1 ./usercase-test-coderl/...