diff --git a/cmd/broker/main.go b/cmd/broker/main.go
index c1ba108..a58aaf5 100644
--- a/cmd/broker/main.go
+++ b/cmd/broker/main.go
@@ -28,6 +28,7 @@ import (
 	"strconv"
 	"strings"
 	"sync"
+	"sync/atomic"
 	"syscall"
 	"time"
 
@@ -60,6 +61,11 @@ const (
 
 type handler struct {
 	apiVersions          []kmsg.ApiVersionsResponseApiKey
+	// nextProducerID is a monotonically-increasing allocator for
+	// InitProducerID responses (OPS-005 #1 stub). Accessed via sync/atomic.
+	// Replace with a proper persistent allocator when full idempotent-producer
+	// dedup lands.
+	nextProducerID       int64
 	store                metadata.Store
 	s3                   storage.S3Client
 	cache                *cache.SegmentCache
@@ -206,6 +212,20 @@ func (h *handler) Handle(ctx context.Context, header *protocol.RequestHeader, re
 		return protocol.EncodeResponse(header.CorrelationID, header.APIVersion, resp), nil
 	case *kmsg.ProduceRequest:
 		return h.handleProduce(ctx, header, req.(*kmsg.ProduceRequest))
+	case *kmsg.InitProducerIDRequest:
+		// OPS-005 #1: minimum-viable INIT_PRODUCER_ID stub. Allocates a
+		// monotonically-increasing producer ID with epoch 0. Does NOT track
+		// sequence numbers or deduplicate (that work is in scope for a later
+		// broker-engineering sprint). This is sufficient to unblock idempotent
+		// producers for development + bp-002 BDR convergence. For production
+		// correctness, full dedup-on-replay is still required.
+		pid := atomic.AddInt64(&h.nextProducerID, 1)
+		resp := kmsg.NewPtrInitProducerIDResponse()
+		resp.ErrorCode = protocol.NONE
+		resp.ProducerID = pid
+		resp.ProducerEpoch = 0
+		resp.ThrottleMillis = 0
+		return protocol.EncodeResponse(header.CorrelationID, header.APIVersion, resp), nil
 	case *kmsg.FetchRequest:
 		return h.handleFetch(ctx, header, req.(*kmsg.FetchRequest))
 	case *kmsg.FindCoordinatorRequest:
@@ -2711,7 +2731,15 @@ func generateApiVersions() []kmsg.ApiVersionsResponseApiKey {
 		{key: protocol.APIKeyOffsetCommit, minVersion: 3, maxVersion: 3},
 		{key: protocol.APIKeyOffsetFetch, minVersion: 5, maxVersion: 5},
 		{key: protocol.APIKeyDescribeGroups, minVersion: 5, maxVersion: 5},
-		{key: protocol.APIKeyListGroups, minVersion: 5, maxVersion: 5},
+		// OPS-005: Java admin-client negotiates LIST_GROUPS in range [0,4].
+		// Narrow 5-5 range breaks `kafka-consumer-groups --list`. Widen to 0-5
+		// — the underlying coordinator handler is version-agnostic.
+		{key: protocol.APIKeyListGroups, minVersion: 0, maxVersion: 5},
+		// OPS-005 #1: idempotent-producer init. Handler is a stub that
+		// allocates a monotonically-increasing producer ID; sequence-number
+		// dedup is NOT yet implemented. Sufficient to unblock franz-go and
+		// Java default producers; production correctness gap tracked.
+		{key: protocol.APIKeyInitProducerID, minVersion: 0, maxVersion: 4},
 		{key: protocol.APIKeyOffsetForLeaderEpoch, minVersion: 3, maxVersion: 3},
 		{key: protocol.APIKeyDescribeConfigs, minVersion: 4, maxVersion: 4},
 		{key: protocol.APIKeyAlterConfigs, minVersion: 1, maxVersion: 1},
@@ -2722,7 +2750,7 @@ func generateApiVersions() []kmsg.ApiVersionsResponseApiKey {
 	}
 	unsupported := []int16{
 		4, 5, 6, 7,
-		21, 22,
+		21, // 22 (InitProducerID) moved to supported — OPS-005 #1 stub handler
 		24, 25, 26,
 	}
 
diff --git a/deploy/helm/kafscale-broker-standalone/Chart.yaml b/deploy/helm/kafscale-broker-standalone/Chart.yaml
new file mode 100644
index 0000000..b5dc1b5
--- /dev/null
+++ b/deploy/helm/kafscale-broker-standalone/Chart.yaml
@@ -0,0 +1,6 @@
+apiVersion: v2
+name: kafscale-broker-standalone
+description: Minimal standalone KafScale broker (etcd + MinIO external). Smoke chart only.
+type: application
+version: 0.1.0
+appVersion: "v1.5.0"
diff --git a/deploy/helm/kafscale-broker-standalone/templates/broker.yaml b/deploy/helm/kafscale-broker-standalone/templates/broker.yaml
new file mode 100644
index 0000000..9aa0f5e
--- /dev/null
+++ b/deploy/helm/kafscale-broker-standalone/templates/broker.yaml
@@ -0,0 +1,52 @@
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: kafscale-broker
+  namespace: {{ .Release.Namespace }}
+  labels:
+    app.kubernetes.io/name: kafscale-broker
+    app.kubernetes.io/part-of: ops-foundation
+spec:
+  replicas: 1
+  selector: { matchLabels: { app.kubernetes.io/name: kafscale-broker } }
+  template:
+    metadata:
+      labels:
+        app.kubernetes.io/name: kafscale-broker
+        app.kubernetes.io/part-of: ops-foundation
+    spec:
+      enableServiceLinks: false
+      containers:
+        - name: broker
+          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
+          imagePullPolicy: {{ .Values.image.pullPolicy }}
+          env:
+            - { name: KAFSCALE_BROKER_ID, value: "0" }
+            - { name: KAFSCALE_BROKER_ADDR, value: ":9092" }
+            - { name: KAFSCALE_BROKER_HOST, value: "kafscale-broker" }
+            - { name: KAFSCALE_BROKER_PORT, value: "9092" }
+            - { name: KAFSCALE_BROKER_ETCD_ENDPOINTS, value: "{{ .Values.etcdEndpoints }}" }
+            - { name: KAFSCALE_BROKER_DATA_DIR, value: "/tmp/data" }
+            - { name: KAFSCALE_BROKER_LOG_LEVEL, value: "info" }
+            - { name: KAFSCALE_S3_BUCKET, value: "{{ .Values.s3Bucket }}" }
+            - { name: KAFSCALE_S3_REGION, value: "us-east-1" }
+            - { name: KAFSCALE_S3_ENDPOINT, value: "{{ .Values.s3Endpoint }}" }
+            - { name: KAFSCALE_S3_ACCESS_KEY, value: "{{ .Values.s3AccessKey }}" }
+            - { name: KAFSCALE_S3_SECRET_KEY, value: "{{ .Values.s3SecretKey }}" }
+            - { name: KAFSCALE_S3_PATH_STYLE, value: "true" }
+          ports:
+            - { name: kafka, containerPort: 9092 }
+---
+apiVersion: v1
+kind: Service
+metadata:
+  name: kafscale-broker
+  namespace: {{ .Release.Namespace }}
+  labels:
+    app.kubernetes.io/name: kafscale-broker
+spec:
+  type: {{ .Values.service.type }}
+  ports:
+    - { name: kafka, port: {{ .Values.service.port }}, targetPort: 9092 }
+  selector:
+    app.kubernetes.io/name: kafscale-broker
diff --git a/deploy/helm/kafscale-broker-standalone/values.yaml b/deploy/helm/kafscale-broker-standalone/values.yaml
new file mode 100644
index 0000000..635f164
--- /dev/null
+++ b/deploy/helm/kafscale-broker-standalone/values.yaml
@@ -0,0 +1,17 @@
+image:
+  repository: ghcr.io/kafscale/kafscale-broker
+  tag: dev
+  pullPolicy: IfNotPresent
+
+etcdEndpoints: "http://etcd:2379"
+s3Endpoint: "http://minio:9000"
+s3Bucket: "kafscale"
+s3AccessKey: "scalytics"
+s3SecretKey: "scalytics"
+
+service:
+  type: ClusterIP
+  port: 9092
+
+labels:
+  app.kubernetes.io/part-of: ops-foundation
diff --git a/pkg/protocol/api.go b/pkg/protocol/api.go
index b237578..f4d81af 100644
--- a/pkg/protocol/api.go
+++ b/pkg/protocol/api.go
@@ -33,6 +33,7 @@ const (
 	APIKeyApiVersion           int16 = 18
 	APIKeyCreateTopics         int16 = 19
 	APIKeyDeleteTopics         int16 = 20
+	APIKeyInitProducerID       int16 = 22 // OPS-005: idempotent-producer init (stub handler)
 	APIKeyOffsetForLeaderEpoch int16 = 23
 	APIKeyDescribeConfigs      int16 = 32
 	APIKeyAlterConfigs         int16 = 33