.dockerignore

@@ -0,0 +1,68 @@
+# .dockerignore for go-cart-actor
+#
+# Goal: Keep Docker build context lean & reproducible.
+# Adjust as project structure evolves.
+
+# Version control & CI metadata
+.git
+.git/
+.gitignore
+.github
+
+# Local tooling / editors
+.vscode
+.idea
+*.iml
+
+# Build artifacts / outputs
+bin/
+build/
+dist/
+out/
+coverage/
+*.coverprofile
+
+# Temporary files
+*.tmp
+*.log
+tmp/
+.tmp/
+
+# Dependency/vendor caches (not used; rely on go modules download)
+vendor/
+
+# Examples / scripts (adjust if you actually need them in build context)
+examples/
+scripts/
+
+# Docs (retain README.md explicitly)
+docs/
+CHANGELOG*
+**/*.md
+!README.md
+
+# Tests (not needed for production build)
+**/*_test.go
+
+# Node / frontend artifacts (if any future addition)
+node_modules/
+
+# Docker / container metadata not needed inside image
+Dockerfile
+
+# Editor swap/backup files
+*~
+*.swp
+
+# Go race / profiling outputs
+*.pprof
+
+# Security / secret placeholders (ensure real secrets never copied)
+*.secret
+*.key
+*.pem
+
+# Keep proto and generated code (do NOT ignore proto/)
+!proto/
+
+# End of file

Dockerfile

@@ -1,17 +1,72 @@
-# syntax=docker/dockerfile:1
+# syntax=docker/dockerfile:1.7
+#
+# Multi-stage build:
+#  1. Build static binary with pinned Go version (matching go.mod).
+#  2. Copy into distroless static nonroot runtime image.
+#
+# Build args (optional):
+#   VERSION      - semantic/app version (default: dev)
+#   GIT_COMMIT   - git SHA (default: unknown)
+#   BUILD_DATE   - RFC3339 build timestamp
+#
+# Example build:
+#   docker build \
+#     --build-arg VERSION=$(git describe --tags --always) \
+#     --build-arg GIT_COMMIT=$(git rev-parse HEAD) \
+#     --build-arg BUILD_DATE=$(date -u +%Y-%m-%dT%H:%M:%SZ) \
+#     -t go-cart-actor:dev .
+#
+# If you add subpackages or directories, no Dockerfile change needed (COPY . .).
+# Ensure a .dockerignore exists to keep context lean.
 
-FROM golang:alpine AS build-stage
-WORKDIR /app
+############################
+# Build Stage
+############################
+FROM golang:1.25-alpine AS build
+WORKDIR /src
+
+# Build metadata (can be overridden at build time)
+ARG VERSION=dev
+ARG GIT_COMMIT=unknown
+ARG BUILD_DATE=unknown
+
+# Ensure reproducible static build
+ENV CGO_ENABLED=0 GOOS=linux GOARCH=amd64
+
+# Dependency caching
 COPY go.mod go.sum ./
-RUN go mod download
+RUN --mount=type=cache,target=/go/pkg/mod \
+    go mod download
 
-COPY proto ./proto
-COPY *.go ./
+# Copy full source (relay on .dockerignore to prune)
+COPY . .
 
-RUN CGO_ENABLED=0 GOOS=linux go build -o /go-cart-actor
+# (Optional) If you do NOT check in generated protobuf code, uncomment generation:
+# RUN go install google.golang.org/protobuf/cmd/protoc-gen-go@latest && \
+#     go install google.golang.org/grpc/cmd/protoc-gen-go-grpc@latest && \
+#     protoc --go_out=. --go_opt=paths=source_relative \
+#            --go-grpc_out=. --go-grpc_opt=paths=source_relative \
+#            proto/*.proto
 
-FROM gcr.io/distroless/base-debian11
+# Build with minimal binary size and embedded metadata
+RUN --mount=type=cache,target=/go/build-cache \
+    go build -trimpath -ldflags="-s -w \
+      -X main.Version=${VERSION} \
+      -X main.GitCommit=${GIT_COMMIT} \
+      -X main.BuildDate=${BUILD_DATE}" \
+      -o /out/go-cart-actor .
+
+############################
+# Runtime Stage
+############################
+# Using distroless static (nonroot) for minimal surface area.
+FROM gcr.io/distroless/static-debian12:nonroot AS runtime
 WORKDIR /
 
-COPY --from=build-stage /go-cart-actor /go-cart-actor
+COPY --from=build /out/go-cart-actor /go-cart-actor
+
+# Document (not expose forcibly) typical ports: 8080 (HTTP), 1337 (gRPC)
+EXPOSE 8080 1337
+
+USER nonroot:nonroot
 ENTRYPOINT ["/go-cart-actor"]

Makefile

@@ -45,6 +45,7 @@ help:
 	@echo "  protogen      Generate protobuf & gRPC code"
 	@echo "  clean_proto   Remove generated *.pb.go files in $(PROTO_DIR)"
 	@echo "  verify_proto  Ensure no root-level *.pb.go files (old layout)"
+
 	@echo "  tidy          Run go mod tidy"
 	@echo "  build         Build the module"
 	@echo "  test          Run tests (verbose)"
@@ -89,6 +90,18 @@ verify_proto:
 	fi
 	@echo "$(GREEN)Proto layout OK (no root-level *.pb.go files).$(RESET)"
 
+
+
+
+
+
+
+
+
+
+
+
+
 tidy:
 	@echo "$(YELLOW)Running go mod tidy...$(RESET)"
 	$(GO) mod tidy

deployment/deployment-no.yaml

@@ -1,276 +0,0 @@
-apiVersion: v1
-kind: Secret
-metadata:
-  name:  klarna-api-credentials
-data:
-  username: ZjQzZDY3YjEtNzA2Yy00NTk2LTliNTgtYjg1YjU2NDEwZTUw
-  password: a2xhcm5hX3Rlc3RfYXBpX0trUWhWVE5yYVZsV2FsTnhTRVp3Y1ZSSFF5UkVNRmxyY25Kd1AxSndQMGdzWmpRelpEWTNZakV0TnpBMll5MDBOVGsyTFRsaU5UZ3RZamcxWWpVMk5ERXdaVFV3TERFc2JUUkNjRFpWU1RsTllsSk1aMlEyVEc4MmRVODNZMkozUlRaaFdEZDViV3AwYkhGV1JqTjVNQzlaYXow
-type: Opaque
----
-apiVersion: apps/v1
-kind: Deployment
-metadata:
-  labels:
-    app: cart-actor
-    arch: amd64
-  name: cart-actor-x86
-spec:
-  replicas: 0
-  selector:
-    matchLabels:
-      app: cart-actor
-      arch: amd64
-  template:
-    metadata:
-      labels:
-        app: cart-actor
-        actor-pool: cart
-        arch: amd64
-    spec:
-      affinity:
-        nodeAffinity:
-          requiredDuringSchedulingIgnoredDuringExecution:
-            nodeSelectorTerms:
-              - matchExpressions:
-                - key: kubernetes.io/arch
-                  operator: NotIn
-                  values:
-                    - arm64
-      volumes:
-        - name: data
-          nfs:
-            path: /i-data/7a8af061/nfs/cart-actor-no
-            server: 10.10.1.10
-      imagePullSecrets:
-        - name: regcred
-      serviceAccountName: default
-      containers:
-        - image: registry.knatofs.se/go-cart-actor-amd64:latest
-          name: cart-actor-amd64
-          imagePullPolicy: Always
-          lifecycle:
-            preStop:
-              exec:
-                command: ["sleep", "15"]
-          ports:
-            - containerPort: 8080
-              name: web
-            - containerPort: 1234
-              name: echo
-            - containerPort: 1337
-              name: rpc
-            - containerPort: 1338
-              name: quorum
-          livenessProbe:
-            httpGet:
-              path: /livez
-              port: web
-            failureThreshold: 1
-            periodSeconds: 10
-          readinessProbe:
-            httpGet:
-              path: /readyz
-              port: web
-            failureThreshold: 2
-            initialDelaySeconds: 2
-            periodSeconds: 10
-          volumeMounts:
-            - mountPath: "/data"
-              name: data
-          resources:
-            limits:
-              memory: "768Mi"
-            requests:
-              memory: "70Mi"
-              cpu: "1200m"
-          env:
-            - name: TZ
-              value: "Europe/Stockholm"
-            - name: KLARNA_API_USERNAME
-              valueFrom:
-                secretKeyRef:
-                  name: klarna-api-credentials
-                  key: username
-            - name: KLARNA_API_PASSWORD
-              valueFrom:
-                secretKeyRef:
-                  name: klarna-api-credentials
-                  key: password
-            - name: POD_IP
-              valueFrom:
-                fieldRef:
-                  fieldPath: status.podIP
-            - name: AMQP_URL
-              value: "amqp://admin:12bananer@rabbitmq.dev:5672/"
-            - name: BASE_URL
-              value: "https://s10n-no.tornberg.me"
-            - name: CART_BASE_URL
-              value: "https://cart-no.tornberg.me"
-            - name: POD_NAME
-              valueFrom:
-                fieldRef:
-                  fieldPath: metadata.name
----
-apiVersion: apps/v1
-kind: Deployment
-metadata:
-  labels:
-    app: cart-actor
-    arch: arm64
-  name: cart-actor-arm64
-spec:
-  replicas: 3
-  selector:
-    matchLabels:
-      app: cart-actor
-      arch: arm64
-  template:
-    metadata:
-      labels:
-        app: cart-actor
-        actor-pool: cart
-        arch: arm64
-    spec:
-      affinity:
-        nodeAffinity:
-          requiredDuringSchedulingIgnoredDuringExecution:
-            nodeSelectorTerms:
-              - matchExpressions:
-                - key: kubernetes.io/hostname
-                  operator: NotIn
-                  values:
-                    - masterpi
-                - key: kubernetes.io/arch
-                  operator: In
-                  values:
-                    - arm64
-      volumes:
-        - name: data
-          nfs:
-            path: /i-data/7a8af061/nfs/cart-actor-no
-            server: 10.10.1.10
-      imagePullSecrets:
-        - name: regcred
-      serviceAccountName: default
-      containers:
-        - image: registry.knatofs.se/go-cart-actor:latest
-          name: cart-actor-arm64
-          imagePullPolicy: Always
-          lifecycle:
-            preStop:
-              exec:
-                command: ["sleep", "15"]
-          ports:
-            - containerPort: 8080
-              name: web
-            - containerPort: 1234
-              name: echo
-            - containerPort: 1337
-              name: rpc
-            - containerPort: 1338
-              name: quorum
-          livenessProbe:
-            httpGet:
-              path: /livez
-              port: web
-            failureThreshold: 1
-            periodSeconds: 10
-          readinessProbe:
-            httpGet:
-              path: /readyz
-              port: web
-            failureThreshold: 2
-            initialDelaySeconds: 2
-            periodSeconds: 10
-          volumeMounts:
-            - mountPath: "/data"
-              name: data
-          resources:
-            limits:
-              memory: "768Mi"
-            requests:
-              memory: "70Mi"
-              cpu: "1200m"
-          env:
-            - name: TZ
-              value: "Europe/Stockholm"
-            - name: KLARNA_API_USERNAME
-              valueFrom:
-                secretKeyRef:
-                  name: klarna-api-credentials
-                  key: username
-            - name: KLARNA_API_PASSWORD
-              valueFrom:
-                secretKeyRef:
-                  name: klarna-api-credentials
-                  key: password
-            - name: POD_IP
-              valueFrom:
-                fieldRef:
-                  fieldPath: status.podIP
-            - name: AMQP_URL
-              value: "amqp://admin:12bananer@rabbitmq.dev:5672/"
-            - name: BASE_URL
-              value: "https://s10n-no.tornberg.me"
-            - name: CART_BASE_URL
-              value: "https://cart-no.tornberg.me"
-            - name: POD_NAME
-              valueFrom:
-                fieldRef:
-                  fieldPath: metadata.name
----
-kind: Service
-apiVersion: v1
-metadata:
-  name: cart-echo
-spec:
-  selector:
-    app: cart-actor
-  type: LoadBalancer
-  ports:
-    - name: echo
-      port: 1234
----
-kind: Service
-apiVersion: v1
-metadata:
-  name: cart-actor
-  annotations:
-    prometheus.io/port: "8080"
-    prometheus.io/scrape: "true"
-    prometheus.io/path: "/metrics"
-spec:
-  selector:
-    app: cart-actor
-  ports:
-    - name: web
-      port: 8080
----
-apiVersion: networking.k8s.io/v1
-kind: Ingress
-metadata:
-  name: cart-ingress
-  annotations:
-    cert-manager.io/cluster-issuer: letsencrypt-prod
-    # nginx.ingress.kubernetes.io/affinity: "cookie"
-    # nginx.ingress.kubernetes.io/session-cookie-name: "cart-affinity"
-    # nginx.ingress.kubernetes.io/session-cookie-expires: "172800"
-    # nginx.ingress.kubernetes.io/session-cookie-max-age: "172800"
-    nginx.ingress.kubernetes.io/proxy-body-size: 4m
-spec:
-  ingressClassName: nginx
-  tls:
-    - hosts:
-        - cart-no.tornberg.me
-      secretName: cart-actor-no-tls-secret
-  rules:
-    - host: cart-no.tornberg.me
-      http:
-        paths:
-          - path: /
-            pathType: Prefix
-            backend:
-              service:
-                name: cart-actor
-                port:
-                  number: 8080

deployment/deployment.yaml

@@ -55,12 +55,8 @@ spec:
                   ports:
                       - containerPort: 8080
                         name: web
-            - containerPort: 1234
-              name: echo
                       - containerPort: 1337
                         name: rpc
-            - containerPort: 1338
-              name: quorum
                   livenessProbe:
                       httpGet:
                           path: /livez
@@ -161,12 +157,8 @@ spec:
                   ports:
                       - containerPort: 8080
                         name: web
-            - containerPort: 1234
-              name: echo
                       - containerPort: 1337
                         name: rpc
-            - containerPort: 1338
-              name: quorum
                   livenessProbe:
                       httpGet:
                           path: /livez
@@ -217,18 +209,6 @@ spec:
 ---
 kind: Service
 apiVersion: v1
-metadata:
-  name: cart-echo
-spec:
-  selector:
-    app: cart-actor
-  type: LoadBalancer
-  ports:
-    - name: echo
-      port: 1234
----
-kind: Service
-apiVersion: v1
 metadata:
     name: cart-actor
     annotations:

deployment/scaling.yaml

@@ -1,4 +1,4 @@
-apiVersion: autoscaling/v1
+apiVersion: autoscaling/v2
 kind: HorizontalPodAutoscaler
 metadata:
     name: cart-scaler-amd
@@ -9,9 +9,47 @@ spec:
         name: cart-actor-x86
     minReplicas: 3
     maxReplicas: 9
-  targetCPUUtilizationPercentage: 30
+    behavior:
+        scaleUp:
+            stabilizationWindowSeconds: 60
+            policies:
+                - type: Percent
+                  value: 100
+                  periodSeconds: 60
+        scaleDown:
+            stabilizationWindowSeconds: 180
+            policies:
+                - type: Percent
+                  value: 50
+                  periodSeconds: 60
+    metrics:
+        - type: Resource
+          resource:
+              name: cpu
+              target:
+                  type: Utilization
+                  averageUtilization: 50
+        # Future custom metric (example):
+        # - type: Pods
+        #   pods:
+        #     metric:
+        #       name: cart_mutations_per_second
+        #     target:
+        #       type: AverageValue
+        #       averageValue: "15"
+        # - type: Object
+        #   object:
+        #     describedObject:
+        #       apiVersion: networking.k8s.io/v1
+        #       kind: Ingress
+        #       name: cart-ingress
+        #     metric:
+        #       name: http_requests_per_second
+        #     target:
+        #       type: Value
+        #       value: "100"
 ---
-apiVersion: autoscaling/v1
+apiVersion: autoscaling/v2
 kind: HorizontalPodAutoscaler
 metadata:
     name: cart-scaler-arm
@@ -22,4 +60,42 @@ spec:
         name: cart-actor-arm64
     minReplicas: 3
     maxReplicas: 9
-  targetCPUUtilizationPercentage: 30
+    behavior:
+        scaleUp:
+            stabilizationWindowSeconds: 60
+            policies:
+                - type: Percent
+                  value: 100
+                  periodSeconds: 60
+        scaleDown:
+            stabilizationWindowSeconds: 180
+            policies:
+                - type: Percent
+                  value: 50
+                  periodSeconds: 60
+    metrics:
+        - type: Resource
+          resource:
+              name: cpu
+              target:
+                  type: Utilization
+                  averageUtilization: 50
+        # Future custom metric (example):
+        # - type: Pods
+        #   pods:
+        #     metric:
+        #       name: cart_mutations_per_second
+        #     target:
+        #       type: AverageValue
+        #       averageValue: "15"
+        # - type: Object
+        #   object:
+        #     describedObject:
+        #       apiVersion: networking.k8s.io/v1
+        #       kind: Ingress
+        #       name: cart-ingress
+        #     metric:
+        #       name: http_requests_per_second
+        #     target:
+        #       type: Value
+        #       value: "100"

proto/control_plane.pb.go

@@ -246,60 +246,7 @@ func (x *CartIdsReply) GetCartIds() []string {
 	return nil
 }
 
-// OwnerChangeRequest notifies peers that ownership of a cart moved (or is moving) to new_host.
-type OwnerChangeRequest struct {
-	state         protoimpl.MessageState `protogen:"open.v1"`
-	CartId        string                 `protobuf:"bytes,1,opt,name=cart_id,json=cartId,proto3" json:"cart_id,omitempty"`
-	NewHost       string                 `protobuf:"bytes,2,opt,name=new_host,json=newHost,proto3" json:"new_host,omitempty"`
-	unknownFields protoimpl.UnknownFields
-	sizeCache     protoimpl.SizeCache
-}
-
-func (x *OwnerChangeRequest) Reset() {
-	*x = OwnerChangeRequest{}
-	mi := &file_control_plane_proto_msgTypes[5]
-	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
-	ms.StoreMessageInfo(mi)
-}
-
-func (x *OwnerChangeRequest) String() string {
-	return protoimpl.X.MessageStringOf(x)
-}
-
-func (*OwnerChangeRequest) ProtoMessage() {}
-
-func (x *OwnerChangeRequest) ProtoReflect() protoreflect.Message {
-	mi := &file_control_plane_proto_msgTypes[5]
-	if x != nil {
-		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
-		if ms.LoadMessageInfo() == nil {
-			ms.StoreMessageInfo(mi)
-		}
-		return ms
-	}
-	return mi.MessageOf(x)
-}
-
-// Deprecated: Use OwnerChangeRequest.ProtoReflect.Descriptor instead.
-func (*OwnerChangeRequest) Descriptor() ([]byte, []int) {
-	return file_control_plane_proto_rawDescGZIP(), []int{5}
-}
-
-func (x *OwnerChangeRequest) GetCartId() string {
-	if x != nil {
-		return x.CartId
-	}
-	return ""
-}
-
-func (x *OwnerChangeRequest) GetNewHost() string {
-	if x != nil {
-		return x.NewHost
-	}
-	return ""
-}
-
-// OwnerChangeAck indicates acceptance or rejection of an ownership change.
+// OwnerChangeAck retained as response type for Closing RPC (ConfirmOwner removed).
 type OwnerChangeAck struct {
 	state         protoimpl.MessageState `protogen:"open.v1"`
 	Accepted      bool                   `protobuf:"varint,1,opt,name=accepted,proto3" json:"accepted,omitempty"`
@@ -310,7 +257,7 @@ type OwnerChangeAck struct {
 
 func (x *OwnerChangeAck) Reset() {
 	*x = OwnerChangeAck{}
-	mi := &file_control_plane_proto_msgTypes[6]
+	mi := &file_control_plane_proto_msgTypes[5]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -322,7 +269,7 @@ func (x *OwnerChangeAck) String() string {
 func (*OwnerChangeAck) ProtoMessage() {}
 
 func (x *OwnerChangeAck) ProtoReflect() protoreflect.Message {
-	mi := &file_control_plane_proto_msgTypes[6]
+	mi := &file_control_plane_proto_msgTypes[5]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -335,7 +282,7 @@ func (x *OwnerChangeAck) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use OwnerChangeAck.ProtoReflect.Descriptor instead.
 func (*OwnerChangeAck) Descriptor() ([]byte, []int) {
-	return file_control_plane_proto_rawDescGZIP(), []int{6}
+	return file_control_plane_proto_rawDescGZIP(), []int{5}
 }
 
 func (x *OwnerChangeAck) GetAccepted() bool {
@@ -362,7 +309,7 @@ type ClosingNotice struct {
 
 func (x *ClosingNotice) Reset() {
 	*x = ClosingNotice{}
-	mi := &file_control_plane_proto_msgTypes[7]
+	mi := &file_control_plane_proto_msgTypes[6]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -374,7 +321,7 @@ func (x *ClosingNotice) String() string {
 func (*ClosingNotice) ProtoMessage() {}
 
 func (x *ClosingNotice) ProtoReflect() protoreflect.Message {
-	mi := &file_control_plane_proto_msgTypes[7]
+	mi := &file_control_plane_proto_msgTypes[6]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -387,7 +334,7 @@ func (x *ClosingNotice) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use ClosingNotice.ProtoReflect.Descriptor instead.
 func (*ClosingNotice) Descriptor() ([]byte, []int) {
-	return file_control_plane_proto_rawDescGZIP(), []int{7}
+	return file_control_plane_proto_rawDescGZIP(), []int{6}
 }
 
 func (x *ClosingNotice) GetHost() string {
@@ -412,10 +359,7 @@ const file_control_plane_proto_rawDesc = "" +
 	"\x0eNegotiateReply\x12\x14\n" +
 	"\x05hosts\x18\x01 \x03(\tR\x05hosts\")\n" +
 	"\fCartIdsReply\x12\x19\n" +
-	"\bcart_ids\x18\x01 \x03(\tR\acartIds\"H\n" +
-	"\x12OwnerChangeRequest\x12\x17\n" +
-	"\acart_id\x18\x01 \x01(\tR\x06cartId\x12\x19\n" +
-	"\bnew_host\x18\x02 \x01(\tR\anewHost\"F\n" +
+	"\bcart_ids\x18\x01 \x03(\tR\acartIds\"F\n" +
 	"\x0eOwnerChangeAck\x12\x1a\n" +
 	"\baccepted\x18\x01 \x01(\bR\baccepted\x12\x18\n" +
 	"\amessage\x18\x02 \x01(\tR\amessage\"#\n" +
@@ -440,26 +384,25 @@ func file_control_plane_proto_rawDescGZIP() []byte {
 	return file_control_plane_proto_rawDescData
 }
 
-var file_control_plane_proto_msgTypes = make([]protoimpl.MessageInfo, 8)
+var file_control_plane_proto_msgTypes = make([]protoimpl.MessageInfo, 7)
 var file_control_plane_proto_goTypes = []any{
 	(*Empty)(nil),            // 0: messages.Empty
 	(*PingReply)(nil),        // 1: messages.PingReply
 	(*NegotiateRequest)(nil), // 2: messages.NegotiateRequest
 	(*NegotiateReply)(nil),   // 3: messages.NegotiateReply
 	(*CartIdsReply)(nil),     // 4: messages.CartIdsReply
-	(*OwnerChangeRequest)(nil), // 5: messages.OwnerChangeRequest
-	(*OwnerChangeAck)(nil),     // 6: messages.OwnerChangeAck
-	(*ClosingNotice)(nil),      // 7: messages.ClosingNotice
+	(*OwnerChangeAck)(nil),   // 5: messages.OwnerChangeAck
+	(*ClosingNotice)(nil),    // 6: messages.ClosingNotice
 }
 var file_control_plane_proto_depIdxs = []int32{
 	0, // 0: messages.ControlPlane.Ping:input_type -> messages.Empty
 	2, // 1: messages.ControlPlane.Negotiate:input_type -> messages.NegotiateRequest
 	0, // 2: messages.ControlPlane.GetCartIds:input_type -> messages.Empty
-	7, // 3: messages.ControlPlane.Closing:input_type -> messages.ClosingNotice
+	6, // 3: messages.ControlPlane.Closing:input_type -> messages.ClosingNotice
 	1, // 4: messages.ControlPlane.Ping:output_type -> messages.PingReply
 	3, // 5: messages.ControlPlane.Negotiate:output_type -> messages.NegotiateReply
 	4, // 6: messages.ControlPlane.GetCartIds:output_type -> messages.CartIdsReply
-	6, // 7: messages.ControlPlane.Closing:output_type -> messages.OwnerChangeAck
+	5, // 7: messages.ControlPlane.Closing:output_type -> messages.OwnerChangeAck
 	4, // [4:8] is the sub-list for method output_type
 	0, // [0:4] is the sub-list for method input_type
 	0, // [0:0] is the sub-list for extension type_name
@@ -478,7 +421,7 @@ func file_control_plane_proto_init() {
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: unsafe.Slice(unsafe.StringData(file_control_plane_proto_rawDesc), len(file_control_plane_proto_rawDesc)),
 			NumEnums:      0,
-			NumMessages:   8,
+			NumMessages:   7,
 			NumExtensions: 0,
 			NumServices:   1,
 		},

synced-pool.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"log"
+	"reflect"
 	"sync"
 	"time"
 
@@ -105,6 +106,27 @@ var (
 		Name: "cart_ring_host_share",
 		Help: "Fractional share of ring vnodes per host",
 	}, []string{"host"})
+
+	cartMutationsTotal = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "cart_mutations_total",
+		Help: "Total number of cart state mutations applied (local + remote routed).",
+	})
+
+	cartMutationFailuresTotal = promauto.NewCounter(prometheus.CounterOpts{
+		Name: "cart_mutation_failures_total",
+		Help: "Total number of failed cart state mutations (local apply errors or remote routing failures).",
+	})
+
+	cartMutationLatencySeconds = promauto.NewHistogramVec(prometheus.HistogramOpts{
+		Name:    "cart_mutation_latency_seconds",
+		Help:    "Latency of cart mutations (successful or failed) in seconds.",
+		Buckets: prometheus.DefBuckets,
+	}, []string{"mutation"})
+
+	cartActiveGrains = promauto.NewGauge(prometheus.GaugeOpts{
+		Name: "cart_active_grains",
+		Help: "Number of active (resident) local grains.",
+	})
 )
 
 func NewSyncedPool(local *GrainLocalPool, hostname string, discovery Discovery) (*SyncedPool, error) {
@@ -564,7 +586,33 @@ func (p *SyncedPool) Apply(id CartId, mutation interface{}) (*CartGrain, error)
 	if err != nil {
 		return nil, err
 	}
-	return grain.Apply(mutation, false)
+	start := time.Now()
+	result, applyErr := grain.Apply(mutation, false)
+
+	// Derive mutation type label (strip pointer)
+	mutationType := "unknown"
+	if mutation != nil {
+		if t := reflect.TypeOf(mutation); t != nil {
+			if t.Kind() == reflect.Ptr {
+				t = t.Elem()
+			}
+			if t.Name() != "" {
+				mutationType = t.Name()
+			}
+		}
+	}
+	cartMutationLatencySeconds.WithLabelValues(mutationType).Observe(time.Since(start).Seconds())
+
+	if applyErr == nil && result != nil {
+		cartMutationsTotal.Inc()
+		if p.ownerHostFor(id) == p.Hostname {
+			// Update active grains gauge only for local ownership
+			cartActiveGrains.Set(float64(p.local.DebugGrainCount()))
+		}
+	} else if applyErr != nil {
+		cartMutationFailuresTotal.Inc()
+	}
+	return result, applyErr
 }
 
 // Get returns current state of a grain (local or remote).