From 1f0f64fbfc17240032d79aa09823c71110906b3a Mon Sep 17 00:00:00 2001
From: manjari <manjari@uber.com>
Date: Tue, 3 Mar 2026 20:35:34 +0000
Subject: [PATCH 1/4] feat(controller) Add and scaffold Cancel API in gateway

---
 core/consumer/registry.go           |   2 +
 example/server/gateway/main.go      |  17 +++-
 gateway/controller/BUILD.bazel      |   2 +
 gateway/controller/cancel.go        |  81 +++++++++++++++++
 gateway/controller/cancel_test.go   |  78 ++++++++++++++++
 gateway/proto/gateway.proto         |  16 ++++
 gateway/protopb/gateway.pb.go       | 135 ++++++++++++++++++++++++----
 gateway/protopb/gateway.pb.yarpc.go | 121 ++++++++++++++++++-------
 gateway/protopb/gateway_grpc.pb.go  |  46 +++++++++-
 9 files changed, 441 insertions(+), 57 deletions(-)
 create mode 100644 gateway/controller/cancel.go
 create mode 100644 gateway/controller/cancel_test.go

diff --git a/core/consumer/registry.go b/core/consumer/registry.go
index 945d9ade..10de82f9 100644
--- a/core/consumer/registry.go
+++ b/core/consumer/registry.go
@@ -32,6 +32,8 @@ const (
 	TopicKeyMerge TopicKey = "merge"
 	// TopicKeyConclude is the pipeline stage where merged requests are published for conclusion.
 	TopicKeyConclude TopicKey = "conclude"
+	// TopicKeyCancel is the pipeline stage where cancellation requests are published for processing.
+	TopicKeyCancel TopicKey = "cancel"
 )
 
 // String returns the topic key as a string.
diff --git a/example/server/gateway/main.go b/example/server/gateway/main.go
index 48eec7ba..9472aea5 100644
--- a/example/server/gateway/main.go
+++ b/example/server/gateway/main.go
@@ -25,8 +25,9 @@ import (
 // GatewayServer wraps the controller and implements the gRPC service interface
 type GatewayServer struct {
 	pb.UnimplementedSubmitQueueGatewayServer
-	pingController *controller.PingController
-	landController *controller.LandController
+	pingController   *controller.PingController
+	landController   *controller.LandController
+	cancelController *controller.CancelController
 }
 
 // Ping delegates to the controller
@@ -39,6 +40,11 @@ func (s *GatewayServer) Land(ctx context.Context, req *pb.LandRequest) (*pb.Land
 	return s.landController.Land(ctx, req)
 }
 
+// Cancel delegates to the controller
+func (s *GatewayServer) Cancel(ctx context.Context, req *pb.CancelRequest) (*pb.CancelResponse, error) {
+	return s.cancelController.Cancel(ctx, req)
+}
+
 func main() {
 	if err := run(); err != nil {
 		fmt.Fprintf(os.Stderr, "Gateway server failure: %v\n", err)
@@ -137,9 +143,12 @@ func run() error {
 	// Create controllers and wrap them for gRPC
 	pingController := controller.NewPingController(logger, scope)
 	landController := controller.NewLandController(logger.Sugar(), scope, cnt, mysqlQueue.Publisher(), "request")
+	cancelController := controller.NewCancelController(logger.Sugar(), scope, mysqlQueue.Publisher(), "cancel")
+
 	gatewayServer := &GatewayServer{
-		pingController: pingController,
-		landController: landController,
+		pingController:   pingController,
+		landController:   landController,
+		cancelController: cancelController,
 	}
 
 	pb.RegisterSubmitQueueGatewayServer(grpcServer, gatewayServer)
diff --git a/gateway/controller/BUILD.bazel b/gateway/controller/BUILD.bazel
index 5329be0e..e9d0333a 100644
--- a/gateway/controller/BUILD.bazel
+++ b/gateway/controller/BUILD.bazel
@@ -3,6 +3,7 @@ load("@rules_go//go:def.bzl", "go_library", "go_test")
 go_library(
     name = "controller",
     srcs = [
+        "cancel.go",
         "land.go",
         "ping.go",
     ],
@@ -23,6 +24,7 @@ go_library(
 go_test(
     name = "controller_test",
     srcs = [
+        "cancel_test.go",
         "land_test.go",
         "ping_test.go",
     ],
diff --git a/gateway/controller/cancel.go b/gateway/controller/cancel.go
new file mode 100644
index 00000000..545d84de
--- /dev/null
+++ b/gateway/controller/cancel.go
@@ -0,0 +1,81 @@
+package controller
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/uber-go/tally/v4"
+	"github.com/uber/submitqueue/entity/queue"
+	extqueue "github.com/uber/submitqueue/extension/queue"
+	pb "github.com/uber/submitqueue/gateway/protopb"
+	"go.uber.org/zap"
+)
+
+// CancelController handles cancel business logic for the gateway
+type CancelController struct {
+	logger       *zap.SugaredLogger
+	metricsScope tally.Scope
+	publisher    extqueue.Publisher
+	topic        string // Topic to publish cancel requests to (e.g., "cancel")
+}
+
+// NewCancelController creates a new instance of the gateway cancel controller.
+// topic: the queue topic to publish cancel requests to (e.g., "cancel")
+func NewCancelController(logger *zap.SugaredLogger, scope tally.Scope, publisher extqueue.Publisher, topic string) *CancelController {
+	return &CancelController{
+		logger:       logger,
+		metricsScope: scope,
+		publisher:    publisher,
+		topic:        topic,
+	}
+}
+
+// Cancel handles the cancel request and returns a response.
+// It publishes the sqid to the cancel topic for async processing.
+// No validation is performed — the orchestrator handles that.
+func (c *CancelController) Cancel(ctx context.Context, req *pb.CancelRequest) (*pb.CancelResponse, error) {
+	start := time.Now()
+	defer func() {
+		c.metricsScope.Timer("cancel_request_latency").Record(time.Since(start))
+	}()
+
+	c.metricsScope.Counter("cancel_request_count").Inc(1)
+
+	sqid := req.Sqid
+
+	if err := c.publishToQueue(ctx, sqid); err != nil {
+		c.logger.Errorw("failed to publish cancel request to queue",
+			"sqid", sqid,
+			"error", err,
+		)
+		return nil, fmt.Errorf("CancelController failed to publish cancel request to queue: %w", err)
+	}
+
+	c.logger.Infow("cancel request published to queue",
+		"sqid", sqid,
+		"topic", c.topic,
+	)
+	c.metricsScope.Counter("cancel_publish_success").Inc(1)
+
+	return &pb.CancelResponse{
+		Sqid: sqid,
+	}, nil
+}
+
+// publishToQueue publishes a cancel request to the cancel queue for async processing.
+func (c *CancelController) publishToQueue(ctx context.Context, sqid string) error {
+	payload := []byte(sqid)
+
+	// Create queue message
+	// - Message ID: sqid for idempotency
+	// - Payload: sqid as bytes
+	// - Partition key: sqid (ensures ordering per request)
+	msg := queue.NewMessage(sqid, payload, sqid, nil)
+
+	if err := c.publisher.Publish(ctx, c.topic, msg); err != nil {
+		return fmt.Errorf("failed to publish message: %w", err)
+	}
+
+	return nil
+}
diff --git a/gateway/controller/cancel_test.go b/gateway/controller/cancel_test.go
new file mode 100644
index 00000000..17930688
--- /dev/null
+++ b/gateway/controller/cancel_test.go
@@ -0,0 +1,78 @@
+package controller
+
+import (
+	"context"
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"github.com/uber-go/tally/v4"
+	"github.com/uber/submitqueue/entity/queue"
+	queuemock "github.com/uber/submitqueue/extension/queue/mock"
+	pb "github.com/uber/submitqueue/gateway/protopb"
+	"go.uber.org/mock/gomock"
+	"go.uber.org/zap"
+)
+
+func TestNewCancelController(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	controller := NewCancelController(zap.NewNop().Sugar(), tally.NoopScope, noopPublisher(ctrl), "cancel")
+	require.NotNil(t, controller)
+}
+
+func TestCancel_ReturnsSqid(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	controller := NewCancelController(zap.NewNop().Sugar(), tally.NoopScope, noopPublisher(ctrl), "cancel")
+	ctx := context.Background()
+
+	req := &pb.CancelRequest{Sqid: "test-queue/123"}
+	resp, err := controller.Cancel(ctx, req)
+
+	require.NoError(t, err)
+	assert.Equal(t, "test-queue/123", resp.Sqid)
+}
+
+func TestCancel_PublishesToQueue(t *testing.T) {
+	var publishedTopic string
+	var publishedMessage queue.Message
+
+	ctrl := gomock.NewController(t)
+	publisher := queuemock.NewMockPublisher(ctrl)
+	publisher.EXPECT().Publish(gomock.Any(), gomock.Any(), gomock.Any()).DoAndReturn(
+		func(ctx context.Context, topic string, msg queue.Message) error {
+			publishedTopic = topic
+			publishedMessage = msg
+			return nil
+		},
+	)
+
+	controller := NewCancelController(zap.NewNop().Sugar(), tally.NoopScope, publisher, "cancel")
+	ctx := context.Background()
+
+	req := &pb.CancelRequest{Sqid: "my-queue/42"}
+	resp, err := controller.Cancel(ctx, req)
+
+	require.NoError(t, err)
+	assert.Equal(t, "my-queue/42", resp.Sqid)
+
+	// Verify message was published to the cancel topic
+	assert.Equal(t, "cancel", publishedTopic)
+	assert.Equal(t, "my-queue/42", publishedMessage.ID)
+	assert.Equal(t, "my-queue/42", publishedMessage.PartitionKey)
+	assert.Equal(t, []byte("my-queue/42"), publishedMessage.Payload)
+}
+
+func TestCancel_ReturnsErrorOnPublishFailure(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	publisher := queuemock.NewMockPublisher(ctrl)
+	publisher.EXPECT().Publish(gomock.Any(), gomock.Any(), gomock.Any()).Return(fmt.Errorf("queue unavailable"))
+
+	controller := NewCancelController(zap.NewNop().Sugar(), tally.NoopScope, publisher, "cancel")
+	ctx := context.Background()
+
+	req := &pb.CancelRequest{Sqid: "test-queue/999"}
+	_, err := controller.Cancel(ctx, req)
+
+	require.Error(t, err)
+}
diff --git a/gateway/proto/gateway.proto b/gateway/proto/gateway.proto
index e1495193..409a553e 100644
--- a/gateway/proto/gateway.proto
+++ b/gateway/proto/gateway.proto
@@ -73,6 +73,18 @@ message LandResponse {
     string sqid = 1;
 }
 
+// CancelRequest defines a request to cancel a previously submitted land request.
+message CancelRequest {
+    // Globally unique identifier for the land request to cancel, as returned by Land.
+    string sqid = 1;
+}
+
+// CancelResponse defines the response to a cancel request.
+message CancelResponse {
+    // Globally unique identifier for the land request that was cancelled.
+    string sqid = 1;
+}
+
 // ***************
 // Error messages, returned as `google.rpc.Status` messages.
 // ***************
@@ -103,4 +115,8 @@ service SubmitQueueGateway {
     // Land lands a set of code changes into a target branch, performing the necessary validations across all other changes in the queue.
     // The processing is asynchronous and returns a LandResponse immediately. The land request is processed in the background.
     rpc Land(LandRequest) returns (LandResponse) {}
+
+    // Cancel cancels a previously submitted land request. The cancellation is asynchronous and
+    // published to a queue for processing. No validation is performed on whether the request exists.
+    rpc Cancel(CancelRequest) returns (CancelResponse) {}
 }
diff --git a/gateway/protopb/gateway.pb.go b/gateway/protopb/gateway.pb.go
index cfc144d5..571e4298 100644
--- a/gateway/protopb/gateway.pb.go
+++ b/gateway/protopb/gateway.pb.go
@@ -364,6 +364,98 @@ func (x *LandResponse) GetSqid() string {
 	return ""
 }
 
+// CancelRequest defines a request to cancel a previously submitted land request.
+type CancelRequest struct {
+	state protoimpl.MessageState `protogen:"open.v1"`
+	// Globally unique identifier for the land request to cancel, as returned by Land.
+	Sqid          string `protobuf:"bytes,1,opt,name=sqid,proto3" json:"sqid,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *CancelRequest) Reset() {
+	*x = CancelRequest{}
+	mi := &file_gateway_proto_msgTypes[5]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *CancelRequest) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*CancelRequest) ProtoMessage() {}
+
+func (x *CancelRequest) ProtoReflect() protoreflect.Message {
+	mi := &file_gateway_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 CancelRequest.ProtoReflect.Descriptor instead.
+func (*CancelRequest) Descriptor() ([]byte, []int) {
+	return file_gateway_proto_rawDescGZIP(), []int{5}
+}
+
+func (x *CancelRequest) GetSqid() string {
+	if x != nil {
+		return x.Sqid
+	}
+	return ""
+}
+
+// CancelResponse defines the response to a cancel request.
+type CancelResponse struct {
+	state protoimpl.MessageState `protogen:"open.v1"`
+	// Globally unique identifier for the land request that was cancelled.
+	Sqid          string `protobuf:"bytes,1,opt,name=sqid,proto3" json:"sqid,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *CancelResponse) Reset() {
+	*x = CancelResponse{}
+	mi := &file_gateway_proto_msgTypes[6]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *CancelResponse) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*CancelResponse) ProtoMessage() {}
+
+func (x *CancelResponse) ProtoReflect() protoreflect.Message {
+	mi := &file_gateway_proto_msgTypes[6]
+	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 CancelResponse.ProtoReflect.Descriptor instead.
+func (*CancelResponse) Descriptor() ([]byte, []int) {
+	return file_gateway_proto_rawDescGZIP(), []int{6}
+}
+
+func (x *CancelResponse) GetSqid() string {
+	if x != nil {
+		return x.Sqid
+	}
+	return ""
+}
+
 // Generic error with metadata. Each custom error type should extend this message.
 type Error struct {
 	state protoimpl.MessageState `protogen:"open.v1"`
@@ -375,7 +467,7 @@ type Error struct {
 
 func (x *Error) Reset() {
 	*x = Error{}
-	mi := &file_gateway_proto_msgTypes[5]
+	mi := &file_gateway_proto_msgTypes[7]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -387,7 +479,7 @@ func (x *Error) String() string {
 func (*Error) ProtoMessage() {}
 
 func (x *Error) ProtoReflect() protoreflect.Message {
-	mi := &file_gateway_proto_msgTypes[5]
+	mi := &file_gateway_proto_msgTypes[7]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -400,7 +492,7 @@ func (x *Error) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use Error.ProtoReflect.Descriptor instead.
 func (*Error) Descriptor() ([]byte, []int) {
-	return file_gateway_proto_rawDescGZIP(), []int{5}
+	return file_gateway_proto_rawDescGZIP(), []int{7}
 }
 
 func (x *Error) GetMessage() string {
@@ -423,7 +515,7 @@ type UnrecognizedQueueError struct {
 
 func (x *UnrecognizedQueueError) Reset() {
 	*x = UnrecognizedQueueError{}
-	mi := &file_gateway_proto_msgTypes[6]
+	mi := &file_gateway_proto_msgTypes[8]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -435,7 +527,7 @@ func (x *UnrecognizedQueueError) String() string {
 func (*UnrecognizedQueueError) ProtoMessage() {}
 
 func (x *UnrecognizedQueueError) ProtoReflect() protoreflect.Message {
-	mi := &file_gateway_proto_msgTypes[6]
+	mi := &file_gateway_proto_msgTypes[8]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -448,7 +540,7 @@ func (x *UnrecognizedQueueError) ProtoReflect() protoreflect.Message {
 
 // Deprecated: Use UnrecognizedQueueError.ProtoReflect.Descriptor instead.
 func (*UnrecognizedQueueError) Descriptor() ([]byte, []int) {
-	return file_gateway_proto_rawDescGZIP(), []int{6}
+	return file_gateway_proto_rawDescGZIP(), []int{8}
 }
 
 func (x *UnrecognizedQueueError) GetError() *Error {
@@ -484,6 +576,10 @@ const file_gateway_proto_rawDesc = "" +
 	"\x06change\x18\x02 \x01(\v2'.uber.devexp.submitqueue.gateway.ChangeR\x06change\x12E\n" +
 	"\bstrategy\x18\x04 \x01(\x0e2).uber.devexp.submitqueue.gateway.StrategyR\bstrategy\"\"\n" +
 	"\fLandResponse\x12\x12\n" +
+	"\x04sqid\x18\x01 \x01(\tR\x04sqid\"#\n" +
+	"\rCancelRequest\x12\x12\n" +
+	"\x04sqid\x18\x01 \x01(\tR\x04sqid\"$\n" +
+	"\x0eCancelResponse\x12\x12\n" +
 	"\x04sqid\x18\x01 \x01(\tR\x04sqid\"!\n" +
 	"\x05Error\x12\x18\n" +
 	"\amessage\x18\x01 \x01(\tR\amessage\"l\n" +
@@ -495,10 +591,11 @@ const file_gateway_proto_rawDesc = "" +
 	"\n" +
 	"\x06REBASE\x10\x01\x12\x11\n" +
 	"\rSQUASH_REBASE\x10\x02\x12\t\n" +
-	"\x05MERGE\x10\x032\xe2\x01\n" +
+	"\x05MERGE\x10\x032\xcf\x02\n" +
 	"\x12SubmitQueueGateway\x12e\n" +
 	"\x04Ping\x12,.uber.devexp.submitqueue.gateway.PingRequest\x1a-.uber.devexp.submitqueue.gateway.PingResponse\"\x00\x12e\n" +
-	"\x04Land\x12,.uber.devexp.submitqueue.gateway.LandRequest\x1a-.uber.devexp.submitqueue.gateway.LandResponse\"\x00Bb\n" +
+	"\x04Land\x12,.uber.devexp.submitqueue.gateway.LandRequest\x1a-.uber.devexp.submitqueue.gateway.LandResponse\"\x00\x12k\n" +
+	"\x06Cancel\x12..uber.devexp.submitqueue.gateway.CancelRequest\x1a/.uber.devexp.submitqueue.gateway.CancelResponse\"\x00Bb\n" +
 	"#com.uber.devexp.submitqueue.gatewayB\fGatewayProtoP\x01Z+github.com/uber/submitqueue/gateway/protopbb\x06proto3"
 
 var (
@@ -514,7 +611,7 @@ func file_gateway_proto_rawDescGZIP() []byte {
 }
 
 var file_gateway_proto_enumTypes = make([]protoimpl.EnumInfo, 1)
-var file_gateway_proto_msgTypes = make([]protoimpl.MessageInfo, 7)
+var file_gateway_proto_msgTypes = make([]protoimpl.MessageInfo, 9)
 var file_gateway_proto_goTypes = []any{
 	(Strategy)(0),                  // 0: uber.devexp.submitqueue.gateway.Strategy
 	(*PingRequest)(nil),            // 1: uber.devexp.submitqueue.gateway.PingRequest
@@ -522,19 +619,23 @@ var file_gateway_proto_goTypes = []any{
 	(*Change)(nil),                 // 3: uber.devexp.submitqueue.gateway.Change
 	(*LandRequest)(nil),            // 4: uber.devexp.submitqueue.gateway.LandRequest
 	(*LandResponse)(nil),           // 5: uber.devexp.submitqueue.gateway.LandResponse
-	(*Error)(nil),                  // 6: uber.devexp.submitqueue.gateway.Error
-	(*UnrecognizedQueueError)(nil), // 7: uber.devexp.submitqueue.gateway.UnrecognizedQueueError
+	(*CancelRequest)(nil),          // 6: uber.devexp.submitqueue.gateway.CancelRequest
+	(*CancelResponse)(nil),         // 7: uber.devexp.submitqueue.gateway.CancelResponse
+	(*Error)(nil),                  // 8: uber.devexp.submitqueue.gateway.Error
+	(*UnrecognizedQueueError)(nil), // 9: uber.devexp.submitqueue.gateway.UnrecognizedQueueError
 }
 var file_gateway_proto_depIdxs = []int32{
 	3, // 0: uber.devexp.submitqueue.gateway.LandRequest.change:type_name -> uber.devexp.submitqueue.gateway.Change
 	0, // 1: uber.devexp.submitqueue.gateway.LandRequest.strategy:type_name -> uber.devexp.submitqueue.gateway.Strategy
-	6, // 2: uber.devexp.submitqueue.gateway.UnrecognizedQueueError.error:type_name -> uber.devexp.submitqueue.gateway.Error
+	8, // 2: uber.devexp.submitqueue.gateway.UnrecognizedQueueError.error:type_name -> uber.devexp.submitqueue.gateway.Error
 	1, // 3: uber.devexp.submitqueue.gateway.SubmitQueueGateway.Ping:input_type -> uber.devexp.submitqueue.gateway.PingRequest
 	4, // 4: uber.devexp.submitqueue.gateway.SubmitQueueGateway.Land:input_type -> uber.devexp.submitqueue.gateway.LandRequest
-	2, // 5: uber.devexp.submitqueue.gateway.SubmitQueueGateway.Ping:output_type -> uber.devexp.submitqueue.gateway.PingResponse
-	5, // 6: uber.devexp.submitqueue.gateway.SubmitQueueGateway.Land:output_type -> uber.devexp.submitqueue.gateway.LandResponse
-	5, // [5:7] is the sub-list for method output_type
-	3, // [3:5] is the sub-list for method input_type
+	6, // 5: uber.devexp.submitqueue.gateway.SubmitQueueGateway.Cancel:input_type -> uber.devexp.submitqueue.gateway.CancelRequest
+	2, // 6: uber.devexp.submitqueue.gateway.SubmitQueueGateway.Ping:output_type -> uber.devexp.submitqueue.gateway.PingResponse
+	5, // 7: uber.devexp.submitqueue.gateway.SubmitQueueGateway.Land:output_type -> uber.devexp.submitqueue.gateway.LandResponse
+	7, // 8: uber.devexp.submitqueue.gateway.SubmitQueueGateway.Cancel:output_type -> uber.devexp.submitqueue.gateway.CancelResponse
+	6, // [6:9] is the sub-list for method output_type
+	3, // [3:6] is the sub-list for method input_type
 	3, // [3:3] is the sub-list for extension type_name
 	3, // [3:3] is the sub-list for extension extendee
 	0, // [0:3] is the sub-list for field type_name
@@ -551,7 +652,7 @@ func file_gateway_proto_init() {
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: unsafe.Slice(unsafe.StringData(file_gateway_proto_rawDesc), len(file_gateway_proto_rawDesc)),
 			NumEnums:      1,
-			NumMessages:   7,
+			NumMessages:   9,
 			NumExtensions: 0,
 			NumServices:   1,
 		},
diff --git a/gateway/protopb/gateway.pb.yarpc.go b/gateway/protopb/gateway.pb.yarpc.go
index 17760cd6..ca8b152c 100644
--- a/gateway/protopb/gateway.pb.yarpc.go
+++ b/gateway/protopb/gateway.pb.yarpc.go
@@ -24,6 +24,7 @@ var _ = ioutil.NopCloser
 type SubmitQueueGatewayYARPCClient interface {
 	Ping(context.Context, *PingRequest, ...yarpc.CallOption) (*PingResponse, error)
 	Land(context.Context, *LandRequest, ...yarpc.CallOption) (*LandResponse, error)
+	Cancel(context.Context, *CancelRequest, ...yarpc.CallOption) (*CancelResponse, error)
 }
 
 func newSubmitQueueGatewayYARPCClient(clientConfig transport.ClientConfig, anyResolver jsonpb.AnyResolver, options ...protobuf.ClientOption) SubmitQueueGatewayYARPCClient {
@@ -46,6 +47,7 @@ func NewSubmitQueueGatewayYARPCClient(clientConfig transport.ClientConfig, optio
 type SubmitQueueGatewayYARPCServer interface {
 	Ping(context.Context, *PingRequest) (*PingResponse, error)
 	Land(context.Context, *LandRequest) (*LandResponse, error)
+	Cancel(context.Context, *CancelRequest) (*CancelResponse, error)
 }
 
 type buildSubmitQueueGatewayYARPCProceduresParams struct {
@@ -79,6 +81,16 @@ func buildSubmitQueueGatewayYARPCProcedures(params buildSubmitQueueGatewayYARPCP
 						},
 					),
 				},
+				{
+					MethodName: "Cancel",
+					Handler: protobuf.NewUnaryHandler(
+						protobuf.UnaryHandlerParams{
+							Handle:      handler.Cancel,
+							NewRequest:  newSubmitQueueGatewayServiceCancelYARPCRequest,
+							AnyResolver: params.AnyResolver,
+						},
+					),
+				},
 			},
 			OnewayHandlerParams: []protobuf.BuildProceduresOnewayHandlerParams{},
 			StreamHandlerParams: []protobuf.BuildProceduresStreamHandlerParams{},
@@ -221,6 +233,18 @@ func (c *_SubmitQueueGatewayYARPCCaller) Land(ctx context.Context, request *Land
 	return response, err
 }
 
+func (c *_SubmitQueueGatewayYARPCCaller) Cancel(ctx context.Context, request *CancelRequest, options ...yarpc.CallOption) (*CancelResponse, error) {
+	responseMessage, err := c.streamClient.Call(ctx, "Cancel", request, newSubmitQueueGatewayServiceCancelYARPCResponse, options...)
+	if responseMessage == nil {
+		return nil, err
+	}
+	response, ok := responseMessage.(*CancelResponse)
+	if !ok {
+		return nil, protobuf.CastError(emptySubmitQueueGatewayServiceCancelYARPCResponse, responseMessage)
+	}
+	return response, err
+}
+
 type _SubmitQueueGatewayYARPCHandler struct {
 	server SubmitQueueGatewayYARPCServer
 }
@@ -257,6 +281,22 @@ func (h *_SubmitQueueGatewayYARPCHandler) Land(ctx context.Context, requestMessa
 	return response, err
 }
 
+func (h *_SubmitQueueGatewayYARPCHandler) Cancel(ctx context.Context, requestMessage proto.Message) (proto.Message, error) {
+	var request *CancelRequest
+	var ok bool
+	if requestMessage != nil {
+		request, ok = requestMessage.(*CancelRequest)
+		if !ok {
+			return nil, protobuf.CastError(emptySubmitQueueGatewayServiceCancelYARPCRequest, requestMessage)
+		}
+	}
+	response, err := h.server.Cancel(ctx, request)
+	if response == nil {
+		return nil, err
+	}
+	return response, err
+}
+
 func newSubmitQueueGatewayServicePingYARPCRequest() proto.Message {
 	return &PingRequest{}
 }
@@ -273,46 +313,59 @@ func newSubmitQueueGatewayServiceLandYARPCResponse() proto.Message {
 	return &LandResponse{}
 }
 
+func newSubmitQueueGatewayServiceCancelYARPCRequest() proto.Message {
+	return &CancelRequest{}
+}
+
+func newSubmitQueueGatewayServiceCancelYARPCResponse() proto.Message {
+	return &CancelResponse{}
+}
+
 var (
-	emptySubmitQueueGatewayServicePingYARPCRequest  = &PingRequest{}
-	emptySubmitQueueGatewayServicePingYARPCResponse = &PingResponse{}
-	emptySubmitQueueGatewayServiceLandYARPCRequest  = &LandRequest{}
-	emptySubmitQueueGatewayServiceLandYARPCResponse = &LandResponse{}
+	emptySubmitQueueGatewayServicePingYARPCRequest    = &PingRequest{}
+	emptySubmitQueueGatewayServicePingYARPCResponse   = &PingResponse{}
+	emptySubmitQueueGatewayServiceLandYARPCRequest    = &LandRequest{}
+	emptySubmitQueueGatewayServiceLandYARPCResponse   = &LandResponse{}
+	emptySubmitQueueGatewayServiceCancelYARPCRequest  = &CancelRequest{}
+	emptySubmitQueueGatewayServiceCancelYARPCResponse = &CancelResponse{}
 )
 
 var yarpcFileDescriptorClosuref1a937782ebbded5 = [][]byte{
 	// gateway.proto
 	[]byte{
-		0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0x8c, 0x93, 0x5d, 0x6f, 0xd3, 0x3e,
-		0x14, 0xc6, 0x9b, 0xbe, 0xad, 0x3d, 0xe9, 0xfe, 0xea, 0xdf, 0x42, 0x28, 0x9a, 0x26, 0xd1, 0x19,
-		0x89, 0x95, 0xb7, 0x54, 0x2a, 0xb7, 0x48, 0xa8, 0x85, 0x30, 0x2e, 0x06, 0xea, 0x1c, 0x7a, 0xc3,
-		0xcd, 0xe4, 0xa4, 0x47, 0x69, 0x24, 0xf2, 0x52, 0xdb, 0x19, 0x8c, 0x7b, 0x3e, 0x0d, 0xdf, 0x8a,
-		0x4f, 0x82, 0xe2, 0xb8, 0x5b, 0x6e, 0x20, 0xbd, 0x3b, 0x76, 0xce, 0x2f, 0xcf, 0x73, 0x1e, 0xdb,
-		0x70, 0x1c, 0x71, 0x85, 0xdf, 0xf8, 0xad, 0x9b, 0x8b, 0x4c, 0x65, 0xe4, 0x51, 0x11, 0xa0, 0x70,
-		0x37, 0x78, 0x83, 0xdf, 0x73, 0x57, 0x16, 0x41, 0x12, 0xab, 0x5d, 0x81, 0x05, 0xba, 0xa6, 0x8d,
-		0x9e, 0x83, 0xbd, 0x8a, 0xd3, 0x88, 0xe1, 0xae, 0x40, 0xa9, 0x88, 0x03, 0x47, 0x09, 0x4a, 0xc9,
-		0x23, 0x74, 0xac, 0x89, 0x35, 0x1d, 0xb2, 0xfd, 0x92, 0xfe, 0xb4, 0x60, 0x54, 0x75, 0xca, 0x3c,
-		0x4b, 0x25, 0xfe, 0xbd, 0x95, 0x9c, 0xc1, 0x48, 0xa2, 0xb8, 0x89, 0x43, 0xbc, 0x4e, 0x79, 0x82,
-		0x4e, 0x5b, 0x7f, 0xb6, 0xcd, 0xde, 0x27, 0x9e, 0x20, 0x39, 0x85, 0xa1, 0x8a, 0x13, 0x94, 0x8a,
-		0x27, 0xb9, 0xd3, 0x99, 0x58, 0xd3, 0x0e, 0xbb, 0xdf, 0x20, 0x27, 0x30, 0xd8, 0x66, 0x52, 0x69,
-		0xb8, 0xab, 0xe1, 0xbb, 0x35, 0x3d, 0x85, 0xfe, 0xdb, 0x2d, 0x4f, 0x23, 0x24, 0x04, 0xba, 0x85,
-		0x88, 0xa5, 0x63, 0x4d, 0x3a, 0xd3, 0x21, 0xd3, 0x35, 0xfd, 0x65, 0x81, 0x7d, 0xc9, 0xd3, 0xcd,
-		0x7e, 0x9e, 0x07, 0xd0, 0xd3, 0xf3, 0x1a, 0x8b, 0xd5, 0x82, 0xbc, 0x81, 0x7e, 0xa8, 0xff, 0xa1,
-		0xad, 0xd9, 0xf3, 0x73, 0xb7, 0x21, 0x26, 0xb7, 0x92, 0x64, 0x06, 0x23, 0x1e, 0x0c, 0xa4, 0x12,
-		0x5c, 0x61, 0x74, 0xab, 0x0d, 0xfe, 0x37, 0x7f, 0xda, 0xf8, 0x0b, 0xdf, 0x00, 0xec, 0x0e, 0xa5,
-		0x14, 0x46, 0x95, 0x59, 0x13, 0x29, 0x81, 0xae, 0xdc, 0xc5, 0x1b, 0x63, 0x56, 0xd7, 0xf4, 0x0c,
-		0x7a, 0x9e, 0x10, 0x99, 0xf8, 0xc7, 0xd1, 0x7c, 0x85, 0x87, 0xeb, 0x54, 0x60, 0x98, 0x45, 0x69,
-		0xfc, 0x03, 0x37, 0x57, 0xa5, 0x6c, 0xc5, 0xbc, 0x86, 0x1e, 0x96, 0x85, 0x26, 0xec, 0xf9, 0x93,
-		0x46, 0x93, 0x1a, 0x63, 0x15, 0x74, 0x1f, 0x5e, 0xbb, 0x16, 0xde, 0xb3, 0x05, 0x0c, 0xf6, 0xa3,
-		0x10, 0x1b, 0x8e, 0xde, 0x79, 0xef, 0x17, 0xeb, 0xcb, 0xcf, 0xe3, 0x16, 0x01, 0xe8, 0x33, 0x6f,
-		0xb9, 0xf0, 0xbd, 0xb1, 0x45, 0xfe, 0x87, 0x63, 0xff, 0x6a, 0xbd, 0xf0, 0x3f, 0x5c, 0x9b, 0xad,
-		0x36, 0x19, 0x42, 0xef, 0xa3, 0xc7, 0x2e, 0xbc, 0x71, 0x67, 0xfe, 0xdb, 0x02, 0xe2, 0x6b, 0x75,
-		0xed, 0xf5, 0xa2, 0x12, 0x27, 0x08, 0xdd, 0xf2, 0x86, 0x91, 0x17, 0x8d, 0x36, 0x6b, 0x57, 0xf6,
-		0xe4, 0xe5, 0x81, 0xdd, 0x55, 0xc6, 0xb4, 0x55, 0xca, 0x94, 0xa9, 0x1f, 0x20, 0x53, 0xbb, 0x49,
-		0x07, 0xc8, 0xd4, 0x8f, 0x92, 0xb6, 0x96, 0x01, 0x3c, 0x0e, 0xb3, 0xa4, 0x89, 0x5a, 0x8e, 0xcc,
-		0xf4, 0xab, 0xf2, 0xbd, 0xae, 0xac, 0x2f, 0xcf, 0xa3, 0x58, 0x6d, 0x8b, 0xc0, 0x0d, 0xb3, 0x64,
-		0x56, 0xb2, 0xb3, 0x1a, 0x34, 0x33, 0xd0, 0x4c, 0x3f, 0xee, 0x3c, 0x08, 0xfa, 0xba, 0x78, 0xf5,
-		0x27, 0x00, 0x00, 0xff, 0xff, 0xe8, 0x4d, 0xf1, 0x97, 0xf6, 0x03, 0x00, 0x00,
+		0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0x8c, 0x94, 0xcb, 0x6e, 0xd3, 0x4c,
+		0x14, 0xc7, 0xe3, 0x5c, 0xdc, 0xe4, 0x38, 0xa9, 0xf2, 0x8d, 0x3e, 0x21, 0x2b, 0xaa, 0x44, 0xea,
+		0x22, 0x1a, 0x6e, 0xb6, 0x14, 0xb6, 0x48, 0x28, 0x29, 0xa6, 0x2c, 0x0a, 0x4a, 0x6d, 0xb2, 0x61,
+		0x53, 0x8d, 0x9d, 0x23, 0xc7, 0xa2, 0xbe, 0xc4, 0x33, 0x2e, 0x94, 0x3d, 0x4f, 0xc3, 0xc3, 0xf0,
+		0x4a, 0xc8, 0xe3, 0x71, 0xeb, 0x05, 0xd4, 0xd9, 0x9d, 0x19, 0x9f, 0xdf, 0xfc, 0xff, 0xe7, 0x22,
+		0xc3, 0x28, 0xa0, 0x1c, 0xbf, 0xd1, 0x5b, 0x33, 0xcd, 0x12, 0x9e, 0x90, 0xc7, 0xb9, 0x87, 0x99,
+		0xb9, 0xc1, 0x1b, 0xfc, 0x9e, 0x9a, 0x2c, 0xf7, 0xa2, 0x90, 0xef, 0x72, 0xcc, 0xd1, 0x94, 0x69,
+		0xc6, 0x29, 0x68, 0xab, 0x30, 0x0e, 0x1c, 0xdc, 0xe5, 0xc8, 0x38, 0xd1, 0xe1, 0x20, 0x42, 0xc6,
+		0x68, 0x80, 0xba, 0x32, 0x55, 0x66, 0x03, 0xa7, 0x3a, 0x1a, 0x3f, 0x15, 0x18, 0x96, 0x99, 0x2c,
+		0x4d, 0x62, 0x86, 0xff, 0x4e, 0x25, 0xc7, 0x30, 0x64, 0x98, 0xdd, 0x84, 0x3e, 0x5e, 0xc5, 0x34,
+		0x42, 0xbd, 0x2d, 0x3e, 0x6b, 0xf2, 0xee, 0x13, 0x8d, 0x90, 0x1c, 0xc1, 0x80, 0x87, 0x11, 0x32,
+		0x4e, 0xa3, 0x54, 0xef, 0x4c, 0x95, 0x59, 0xc7, 0xb9, 0xbf, 0x20, 0x13, 0xe8, 0x6f, 0x13, 0xc6,
+		0x05, 0xdc, 0x15, 0xf0, 0xdd, 0xd9, 0x38, 0x02, 0xf5, 0x6c, 0x4b, 0xe3, 0x00, 0x09, 0x81, 0x6e,
+		0x9e, 0x85, 0x4c, 0x57, 0xa6, 0x9d, 0xd9, 0xc0, 0x11, 0xb1, 0xf1, 0x4b, 0x01, 0xed, 0x82, 0xc6,
+		0x9b, 0xaa, 0x9e, 0xff, 0xa1, 0x27, 0xea, 0x95, 0x16, 0xcb, 0x03, 0x79, 0x0b, 0xaa, 0x2f, 0xde,
+		0x10, 0xd6, 0xb4, 0xf9, 0xa9, 0xd9, 0xd0, 0x26, 0xb3, 0x94, 0x74, 0x24, 0x46, 0x6c, 0xe8, 0x33,
+		0x9e, 0x51, 0x8e, 0xc1, 0xad, 0x30, 0x78, 0x38, 0x7f, 0xd6, 0xf8, 0x84, 0x2b, 0x01, 0xe7, 0x0e,
+		0x35, 0x0c, 0x18, 0x96, 0x66, 0x65, 0x4b, 0x09, 0x74, 0xd9, 0x2e, 0xdc, 0x48, 0xb3, 0x22, 0x36,
+		0x4e, 0x60, 0x74, 0x46, 0x63, 0x1f, 0xaf, 0xab, 0x92, 0xfe, 0x96, 0xf4, 0x04, 0x0e, 0xab, 0xa4,
+		0x07, 0x9e, 0x3a, 0x86, 0x9e, 0x9d, 0x65, 0x49, 0xf6, 0xc0, 0x94, 0xaf, 0xe1, 0xd1, 0x3a, 0xce,
+		0xd0, 0x4f, 0x82, 0x38, 0xfc, 0x81, 0x9b, 0xcb, 0xa2, 0x82, 0x92, 0x79, 0x03, 0x3d, 0x2c, 0x02,
+		0x41, 0x68, 0xf3, 0xa7, 0x8d, 0xf5, 0x0a, 0xcc, 0x29, 0xa1, 0xfb, 0x39, 0xb4, 0x6b, 0x73, 0x78,
+		0xbe, 0x80, 0x7e, 0xd5, 0x15, 0xa2, 0xc1, 0xc1, 0x3b, 0xfb, 0xfd, 0x62, 0x7d, 0xf1, 0x79, 0xdc,
+		0x22, 0x00, 0xaa, 0x63, 0x2f, 0x17, 0xae, 0x3d, 0x56, 0xc8, 0x7f, 0x30, 0x72, 0x2f, 0xd7, 0x0b,
+		0xf7, 0xc3, 0x95, 0xbc, 0x6a, 0x93, 0x01, 0xf4, 0x3e, 0xda, 0xce, 0xb9, 0x3d, 0xee, 0xcc, 0x7f,
+		0xb7, 0x81, 0xb8, 0x42, 0x5d, 0x78, 0x3d, 0x2f, 0xc5, 0x09, 0x42, 0xb7, 0x58, 0x56, 0xf2, 0xb2,
+		0xd1, 0x66, 0x6d, 0xfb, 0x27, 0xaf, 0xf6, 0xcc, 0x2e, 0x7b, 0x6c, 0xb4, 0x0a, 0x99, 0x62, 0x80,
+		0x7b, 0xc8, 0xd4, 0x96, 0x72, 0x0f, 0x99, 0xfa, 0x56, 0x18, 0x2d, 0xf2, 0x15, 0xd4, 0x72, 0xbc,
+		0xc4, 0x6c, 0xde, 0xd4, 0xfa, 0xb2, 0x4c, 0xac, 0xbd, 0xf3, 0x2b, 0xb1, 0xa5, 0x07, 0x27, 0x7e,
+		0x12, 0x35, 0x71, 0xcb, 0xa1, 0x6c, 0xf5, 0xaa, 0xf8, 0xcf, 0xac, 0x94, 0x2f, 0x2f, 0x82, 0x90,
+		0x6f, 0x73, 0xcf, 0xf4, 0x93, 0xc8, 0x2a, 0x58, 0xab, 0x06, 0x59, 0x12, 0xb2, 0xc4, 0x4f, 0x29,
+		0xf5, 0x3c, 0x55, 0x04, 0xaf, 0xff, 0x04, 0x00, 0x00, 0xff, 0xff, 0xf4, 0xdb, 0xc5, 0xbd, 0xae,
+		0x04, 0x00, 0x00,
 	},
 }
 
diff --git a/gateway/protopb/gateway_grpc.pb.go b/gateway/protopb/gateway_grpc.pb.go
index 04820f4d..695ba3bc 100644
--- a/gateway/protopb/gateway_grpc.pb.go
+++ b/gateway/protopb/gateway_grpc.pb.go
@@ -19,8 +19,9 @@ import (
 const _ = grpc.SupportPackageIsVersion9
 
 const (
-	SubmitQueueGateway_Ping_FullMethodName = "/uber.devexp.submitqueue.gateway.SubmitQueueGateway/Ping"
-	SubmitQueueGateway_Land_FullMethodName = "/uber.devexp.submitqueue.gateway.SubmitQueueGateway/Land"
+	SubmitQueueGateway_Ping_FullMethodName   = "/uber.devexp.submitqueue.gateway.SubmitQueueGateway/Ping"
+	SubmitQueueGateway_Land_FullMethodName   = "/uber.devexp.submitqueue.gateway.SubmitQueueGateway/Land"
+	SubmitQueueGateway_Cancel_FullMethodName = "/uber.devexp.submitqueue.gateway.SubmitQueueGateway/Cancel"
 )
 
 // SubmitQueueGatewayClient is the client API for SubmitQueueGateway service.
@@ -34,6 +35,9 @@ type SubmitQueueGatewayClient interface {
 	// Land lands a set of code changes into a target branch, performing the necessary validations across all other changes in the queue.
 	// The processing is asynchronous and returns a LandResponse immediately. The land request is processed in the background.
 	Land(ctx context.Context, in *LandRequest, opts ...grpc.CallOption) (*LandResponse, error)
+	// Cancel cancels a previously submitted land request. The cancellation is asynchronous and
+	// published to a queue for processing. No validation is performed on whether the request exists.
+	Cancel(ctx context.Context, in *CancelRequest, opts ...grpc.CallOption) (*CancelResponse, error)
 }
 
 type submitQueueGatewayClient struct {
@@ -64,6 +68,16 @@ func (c *submitQueueGatewayClient) Land(ctx context.Context, in *LandRequest, op
 	return out, nil
 }
 
+func (c *submitQueueGatewayClient) Cancel(ctx context.Context, in *CancelRequest, opts ...grpc.CallOption) (*CancelResponse, error) {
+	cOpts := append([]grpc.CallOption{grpc.StaticMethod()}, opts...)
+	out := new(CancelResponse)
+	err := c.cc.Invoke(ctx, SubmitQueueGateway_Cancel_FullMethodName, in, out, cOpts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
 // SubmitQueueGatewayServer is the server API for SubmitQueueGateway service.
 // All implementations must embed UnimplementedSubmitQueueGatewayServer
 // for forward compatibility.
@@ -75,6 +89,9 @@ type SubmitQueueGatewayServer interface {
 	// Land lands a set of code changes into a target branch, performing the necessary validations across all other changes in the queue.
 	// The processing is asynchronous and returns a LandResponse immediately. The land request is processed in the background.
 	Land(context.Context, *LandRequest) (*LandResponse, error)
+	// Cancel cancels a previously submitted land request. The cancellation is asynchronous and
+	// published to a queue for processing. No validation is performed on whether the request exists.
+	Cancel(context.Context, *CancelRequest) (*CancelResponse, error)
 	mustEmbedUnimplementedSubmitQueueGatewayServer()
 }
 
@@ -91,6 +108,9 @@ func (UnimplementedSubmitQueueGatewayServer) Ping(context.Context, *PingRequest)
 func (UnimplementedSubmitQueueGatewayServer) Land(context.Context, *LandRequest) (*LandResponse, error) {
 	return nil, status.Error(codes.Unimplemented, "method Land not implemented")
 }
+func (UnimplementedSubmitQueueGatewayServer) Cancel(context.Context, *CancelRequest) (*CancelResponse, error) {
+	return nil, status.Error(codes.Unimplemented, "method Cancel not implemented")
+}
 func (UnimplementedSubmitQueueGatewayServer) mustEmbedUnimplementedSubmitQueueGatewayServer() {}
 func (UnimplementedSubmitQueueGatewayServer) testEmbeddedByValue()                            {}
 
@@ -148,6 +168,24 @@ func _SubmitQueueGateway_Land_Handler(srv interface{}, ctx context.Context, dec
 	return interceptor(ctx, in, info, handler)
 }
 
+func _SubmitQueueGateway_Cancel_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(CancelRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(SubmitQueueGatewayServer).Cancel(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: SubmitQueueGateway_Cancel_FullMethodName,
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(SubmitQueueGatewayServer).Cancel(ctx, req.(*CancelRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
 // SubmitQueueGateway_ServiceDesc is the grpc.ServiceDesc for SubmitQueueGateway service.
 // It's only intended for direct use with grpc.RegisterService,
 // and not to be introspected or modified (even as a copy)
@@ -163,6 +201,10 @@ var SubmitQueueGateway_ServiceDesc = grpc.ServiceDesc{
 			MethodName: "Land",
 			Handler:    _SubmitQueueGateway_Land_Handler,
 		},
+		{
+			MethodName: "Cancel",
+			Handler:    _SubmitQueueGateway_Cancel_Handler,
+		},
 	},
 	Streams:  []grpc.StreamDesc{},
 	Metadata: "gateway.proto",

From 165a2bf559e6d2c7c911e117659dc0ae9b190a36 Mon Sep 17 00:00:00 2001
From: manjari <manjari@uber.com>
Date: Tue, 3 Mar 2026 20:37:43 +0000
Subject: [PATCH 2/4] udpate comment

---
 gateway/controller/cancel.go | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/gateway/controller/cancel.go b/gateway/controller/cancel.go
index 545d84de..0956a3fd 100644
--- a/gateway/controller/cancel.go
+++ b/gateway/controller/cancel.go
@@ -44,6 +44,8 @@ func (c *CancelController) Cancel(ctx context.Context, req *pb.CancelRequest) (*
 
 	sqid := req.Sqid
 
+	// TODO: Insert the request to the event store
+
 	if err := c.publishToQueue(ctx, sqid); err != nil {
 		c.logger.Errorw("failed to publish cancel request to queue",
 			"sqid", sqid,

From ff0ef2051f0e4b1b0a1de7541672154c467b4005 Mon Sep 17 00:00:00 2001
From: manjari <manjari@uber.com>
Date: Wed, 4 Mar 2026 01:00:50 +0000
Subject: [PATCH 3/4] use core/metrics

---
 gateway/controller/BUILD.bazel |  1 +
 gateway/controller/cancel.go   | 13 ++++---------
 gateway/controller/land.go     | 13 ++++---------
 3 files changed, 9 insertions(+), 18 deletions(-)

diff --git a/gateway/controller/BUILD.bazel b/gateway/controller/BUILD.bazel
index e9d0333a..e96c2a95 100644
--- a/gateway/controller/BUILD.bazel
+++ b/gateway/controller/BUILD.bazel
@@ -11,6 +11,7 @@ go_library(
     visibility = ["//visibility:public"],
     deps = [
         "//core/errs",
+        "//core/metrics",
         "//entity",
         "//entity/queue",
         "//extension/counter",
diff --git a/gateway/controller/cancel.go b/gateway/controller/cancel.go
index 0956a3fd..ab372b11 100644
--- a/gateway/controller/cancel.go
+++ b/gateway/controller/cancel.go
@@ -3,9 +3,9 @@ package controller
 import (
 	"context"
 	"fmt"
-	"time"
 
 	"github.com/uber-go/tally/v4"
+	"github.com/uber/submitqueue/core/metrics"
 	"github.com/uber/submitqueue/entity/queue"
 	extqueue "github.com/uber/submitqueue/extension/queue"
 	pb "github.com/uber/submitqueue/gateway/protopb"
@@ -34,13 +34,9 @@ func NewCancelController(logger *zap.SugaredLogger, scope tally.Scope, publisher
 // Cancel handles the cancel request and returns a response.
 // It publishes the sqid to the cancel topic for async processing.
 // No validation is performed — the orchestrator handles that.
-func (c *CancelController) Cancel(ctx context.Context, req *pb.CancelRequest) (*pb.CancelResponse, error) {
-	start := time.Now()
-	defer func() {
-		c.metricsScope.Timer("cancel_request_latency").Record(time.Since(start))
-	}()
-
-	c.metricsScope.Counter("cancel_request_count").Inc(1)
+func (c *CancelController) Cancel(ctx context.Context, req *pb.CancelRequest) (resp *pb.CancelResponse, retErr error) {
+	op := metrics.Begin(c.metricsScope, "cancel")
+	defer func() { op.Complete(retErr) }()
 
 	sqid := req.Sqid
 
@@ -58,7 +54,6 @@ func (c *CancelController) Cancel(ctx context.Context, req *pb.CancelRequest) (*
 		"sqid", sqid,
 		"topic", c.topic,
 	)
-	c.metricsScope.Counter("cancel_publish_success").Inc(1)
 
 	return &pb.CancelResponse{
 		Sqid: sqid,
diff --git a/gateway/controller/land.go b/gateway/controller/land.go
index fe5d861d..1eb70060 100644
--- a/gateway/controller/land.go
+++ b/gateway/controller/land.go
@@ -4,10 +4,10 @@ import (
 	"context"
 	"errors"
 	"fmt"
-	"time"
 
 	"github.com/uber-go/tally/v4"
 	"github.com/uber/submitqueue/core/errs"
+	"github.com/uber/submitqueue/core/metrics"
 	"github.com/uber/submitqueue/entity"
 	"github.com/uber/submitqueue/entity/queue"
 	"github.com/uber/submitqueue/extension/counter"
@@ -47,13 +47,9 @@ func NewLandController(logger *zap.SugaredLogger, scope tally.Scope, counter cou
 }
 
 // Land handles the land request and returns a response
-func (c *LandController) Land(ctx context.Context, req *pb.LandRequest) (*pb.LandResponse, error) {
-	start := time.Now()
-	defer func() {
-		c.metricsScope.Timer("land_request_latency").Record(time.Since(start))
-	}()
-
-	c.metricsScope.Counter("land_request_count").Inc(1)
+func (c *LandController) Land(ctx context.Context, req *pb.LandRequest) (resp *pb.LandResponse, retErr error) {
+	op := metrics.Begin(c.metricsScope, "land")
+	defer func() { op.Complete(retErr) }()
 
 	// Validate required fields.
 	if req.Queue == "" {
@@ -117,7 +113,6 @@ func (c *LandController) Land(ctx context.Context, req *pb.LandRequest) (*pb.Lan
 		"sqid", request.ID,
 		"topic", c.topic,
 	)
-	c.metricsScope.Counter("publish_success").Inc(1)
 
 	return &pb.LandResponse{
 		Sqid: request.ID,

From 65738db1ec136eeefffea501204f00845261c247 Mon Sep 17 00:00:00 2001
From: manjari <manjari@uber.com>
Date: Wed, 4 Mar 2026 18:28:00 +0000
Subject: [PATCH 4/4] address comments

---
 entity/BUILD.bazel                  |   2 +
 entity/cancel.go                    |  22 ++++
 entity/cancel_test.go               |  63 +++++++++++
 gateway/controller/cancel.go        |  39 +++++--
 gateway/controller/cancel_test.go   |  24 ++++-
 gateway/proto/gateway.proto         |  32 +++++-
 gateway/protopb/gateway.pb.go       | 158 +++++++++++++++++++++++-----
 gateway/protopb/gateway.pb.yarpc.go |  74 +++++++------
 gateway/protopb/gateway_grpc.pb.go  |  16 ++-
 9 files changed, 352 insertions(+), 78 deletions(-)
 create mode 100644 entity/cancel.go
 create mode 100644 entity/cancel_test.go

diff --git a/entity/BUILD.bazel b/entity/BUILD.bazel
index ccd288d0..2bcf95d7 100644
--- a/entity/BUILD.bazel
+++ b/entity/BUILD.bazel
@@ -6,6 +6,7 @@ go_library(
         "batch.go",
         "batch_dependent.go",
         "build.go",
+        "cancel.go",
         "change_provider.go",
         "queue_config.go",
         "request.go",
@@ -20,6 +21,7 @@ go_test(
     srcs = [
         "batch_test.go",
         "build_test.go",
+        "cancel_test.go",
         "request_test.go",
     ],
     embed = [":entity"],
diff --git a/entity/cancel.go b/entity/cancel.go
new file mode 100644
index 00000000..a024508d
--- /dev/null
+++ b/entity/cancel.go
@@ -0,0 +1,22 @@
+package entity
+
+import "encoding/json"
+
+// Cancel represents a request to cancel a previously submitted land request.
+// The object is immutable after creation.
+type Cancel struct {
+	// Sqid is the globally unique identifier of the land request to cancel.
+	Sqid string `json:"sqid"`
+}
+
+// ToBytes serializes the Cancel to JSON bytes for queue message payload.
+func (c Cancel) ToBytes() ([]byte, error) {
+	return json.Marshal(c)
+}
+
+// CancelFromBytes deserializes a Cancel from JSON bytes.
+func CancelFromBytes(data []byte) (Cancel, error) {
+	var c Cancel
+	err := json.Unmarshal(data, &c)
+	return c, err
+}
diff --git a/entity/cancel_test.go b/entity/cancel_test.go
new file mode 100644
index 00000000..d6756804
--- /dev/null
+++ b/entity/cancel_test.go
@@ -0,0 +1,63 @@
+package entity
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestCancel_ToBytes(t *testing.T) {
+	cancel := Cancel{
+		Sqid: "test-queue/123",
+	}
+
+	data, err := cancel.ToBytes()
+	require.NoError(t, err)
+	assert.Contains(t, string(data), "test-queue/123")
+}
+
+func TestCancelFromBytes(t *testing.T) {
+	original := Cancel{
+		Sqid: "my-queue/999",
+	}
+
+	data, err := original.ToBytes()
+	require.NoError(t, err)
+
+	deserialized, err := CancelFromBytes(data)
+	require.NoError(t, err)
+	assert.Equal(t, original, deserialized)
+}
+
+func TestCancelFromBytes_InvalidJSON(t *testing.T) {
+	_, err := CancelFromBytes([]byte(`{"invalid": json"}`))
+	assert.Error(t, err)
+}
+
+func TestCancel_SerializationRoundTrip(t *testing.T) {
+	tests := []struct {
+		name   string
+		cancel Cancel
+	}{
+		{
+			name:   "standard sqid",
+			cancel: Cancel{Sqid: "queue1/100"},
+		},
+		{
+			name:   "long sqid",
+			cancel: Cancel{Sqid: "my-long-queue-name/999999"},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			data, err := tt.cancel.ToBytes()
+			require.NoError(t, err)
+
+			deserialized, err := CancelFromBytes(data)
+			require.NoError(t, err)
+			assert.Equal(t, tt.cancel, deserialized)
+		})
+	}
+}
diff --git a/gateway/controller/cancel.go b/gateway/controller/cancel.go
index ab372b11..4f58029c 100644
--- a/gateway/controller/cancel.go
+++ b/gateway/controller/cancel.go
@@ -6,6 +6,7 @@ import (
 
 	"github.com/uber-go/tally/v4"
 	"github.com/uber/submitqueue/core/metrics"
+	"github.com/uber/submitqueue/entity"
 	"github.com/uber/submitqueue/entity/queue"
 	extqueue "github.com/uber/submitqueue/extension/queue"
 	pb "github.com/uber/submitqueue/gateway/protopb"
@@ -40,9 +41,25 @@ func (c *CancelController) Cancel(ctx context.Context, req *pb.CancelRequest) (r
 
 	sqid := req.Sqid
 
-	// TODO: Insert the request to the event store
+	if sqid == "" {
+		return &pb.CancelResponse{
+			Error: &pb.Error{Message: "sqid is required"},
+		}, nil
+	}
+
+	// TODO -
+	// Look up event store to see if sqid exists -
+	//  - if found and request is already in a terminal state; return cancellation failed with appropriate
+	//    error message.
+	//  - if found and request is not in a terminal state; publish a cancel entity onto the cancel topic
+	//    to be picked up by the orchestrator.
+	//  - if not found; publish a cancel entity onto the cancel topic
+	//    to be picked up by the orchestrator.
+	cancel := entity.Cancel{
+		Sqid: sqid,
+	}
 
-	if err := c.publishToQueue(ctx, sqid); err != nil {
+	if err := c.publishToQueue(ctx, cancel); err != nil {
 		c.logger.Errorw("failed to publish cancel request to queue",
 			"sqid", sqid,
 			"error", err,
@@ -56,19 +73,23 @@ func (c *CancelController) Cancel(ctx context.Context, req *pb.CancelRequest) (r
 	)
 
 	return &pb.CancelResponse{
-		Sqid: sqid,
+		Sqid:          sqid,
+		CurrentStatus: pb.RequestStatus_CANCELLATION_ACCEPTED,
 	}, nil
 }
 
-// publishToQueue publishes a cancel request to the cancel queue for async processing.
-func (c *CancelController) publishToQueue(ctx context.Context, sqid string) error {
-	payload := []byte(sqid)
+// publishToQueue publishes a cancel entity to the cancel queue for async processing.
+func (c *CancelController) publishToQueue(ctx context.Context, cancel entity.Cancel) error {
+	payload, err := cancel.ToBytes()
+	if err != nil {
+		return fmt.Errorf("failed to serialize cancel entity: %w", err)
+	}
 
 	// Create queue message
 	// - Message ID: sqid for idempotency
-	// - Payload: sqid as bytes
-	// - Partition key: sqid (ensures ordering per request)
-	msg := queue.NewMessage(sqid, payload, sqid, nil)
+	// - Payload: serialized Cancel entity
+	// - Partition key: empty (no inherent ordering for cancel requests)
+	msg := queue.NewMessage(cancel.Sqid, payload, "", nil)
 
 	if err := c.publisher.Publish(ctx, c.topic, msg); err != nil {
 		return fmt.Errorf("failed to publish message: %w", err)
diff --git a/gateway/controller/cancel_test.go b/gateway/controller/cancel_test.go
index 17930688..00496c24 100644
--- a/gateway/controller/cancel_test.go
+++ b/gateway/controller/cancel_test.go
@@ -8,6 +8,7 @@ import (
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"github.com/uber-go/tally/v4"
+	"github.com/uber/submitqueue/entity"
 	"github.com/uber/submitqueue/entity/queue"
 	queuemock "github.com/uber/submitqueue/extension/queue/mock"
 	pb "github.com/uber/submitqueue/gateway/protopb"
@@ -21,6 +22,21 @@ func TestNewCancelController(t *testing.T) {
 	require.NotNil(t, controller)
 }
 
+func TestCancel_ReturnsErrorOnEmptySqid(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	controller := NewCancelController(zap.NewNop().Sugar(), tally.NoopScope, noopPublisher(ctrl), "cancel")
+	ctx := context.Background()
+
+	req := &pb.CancelRequest{Sqid: ""}
+	resp, err := controller.Cancel(ctx, req)
+
+	require.NoError(t, err)
+	assert.Empty(t, resp.Sqid)
+	assert.Equal(t, pb.RequestStatus_UNKNOWN, resp.CurrentStatus)
+	require.NotNil(t, resp.Error)
+	assert.Equal(t, "sqid is required", resp.Error.Message)
+}
+
 func TestCancel_ReturnsSqid(t *testing.T) {
 	ctrl := gomock.NewController(t)
 	controller := NewCancelController(zap.NewNop().Sugar(), tally.NoopScope, noopPublisher(ctrl), "cancel")
@@ -31,6 +47,7 @@ func TestCancel_ReturnsSqid(t *testing.T) {
 
 	require.NoError(t, err)
 	assert.Equal(t, "test-queue/123", resp.Sqid)
+	assert.Equal(t, pb.RequestStatus_CANCELLATION_ACCEPTED, resp.CurrentStatus)
 }
 
 func TestCancel_PublishesToQueue(t *testing.T) {
@@ -55,12 +72,17 @@ func TestCancel_PublishesToQueue(t *testing.T) {
 
 	require.NoError(t, err)
 	assert.Equal(t, "my-queue/42", resp.Sqid)
+	assert.Equal(t, pb.RequestStatus_CANCELLATION_ACCEPTED, resp.CurrentStatus)
 
 	// Verify message was published to the cancel topic
 	assert.Equal(t, "cancel", publishedTopic)
 	assert.Equal(t, "my-queue/42", publishedMessage.ID)
 	assert.Equal(t, "my-queue/42", publishedMessage.PartitionKey)
-	assert.Equal(t, []byte("my-queue/42"), publishedMessage.Payload)
+
+	// Verify payload is a serialized Cancel entity
+	cancel, err := entity.CancelFromBytes(publishedMessage.Payload)
+	require.NoError(t, err)
+	assert.Equal(t, "my-queue/42", cancel.Sqid)
 }
 
 func TestCancel_ReturnsErrorOnPublishFailure(t *testing.T) {
diff --git a/gateway/proto/gateway.proto b/gateway/proto/gateway.proto
index 409a553e..c80229f8 100644
--- a/gateway/proto/gateway.proto
+++ b/gateway/proto/gateway.proto
@@ -79,10 +79,32 @@ message CancelRequest {
     string sqid = 1;
 }
 
+// RequestStatus defines the possible states of a land request.
+enum RequestStatus {
+    // Unknown status.
+    UNKNOWN = 0;
+    // Initial state of a land request. Confirmed by the system but processing has not started.
+    NEW = 1;
+    // The request has been validated (duplicate check, merge check etc.) successfully.
+    VALIDATED = 2;
+    // The request is being processed.
+    PROCESSING = 3;
+    // The request has been successfully processed and landed. Terminal state.
+    LANDED = 4;
+    // The cancellation request has been accepted and is being processed.
+    CANCELLATION_ACCEPTED = 5;
+    // The request has been cancelled. Terminal state.
+    CANCELLED = 6;
+}
+
 // CancelResponse defines the response to a cancel request.
 message CancelResponse {
-    // Globally unique identifier for the land request that was cancelled.
+    // Globally unique identifier for the land request that was requested to be cancelled.
     string sqid = 1;
+    // Current status of the land request at the time of cancellation request.
+    RequestStatus current_status = 2;
+    // Optional error describing why the cancellation could not be completed.
+    Error error = 3;
 }
 
 // ***************
@@ -116,7 +138,11 @@ service SubmitQueueGateway {
     // The processing is asynchronous and returns a LandResponse immediately. The land request is processed in the background.
     rpc Land(LandRequest) returns (LandResponse) {}
 
-    // Cancel cancels a previously submitted land request. The cancellation is asynchronous and
-    // published to a queue for processing. No validation is performed on whether the request exists.
+    // Cancel requests cancellation of a previously submitted land request.
+    // The cancellation is asynchronous and published to a queue for
+    // processing. Note that cancellation is best effort and not guaranteed.
+    // To check for the status of the request, use Status API (TODO). A
+    // "Cancelled" status indicates that the requested cancellation was
+    // successful.
     rpc Cancel(CancelRequest) returns (CancelResponse) {}
 }
diff --git a/gateway/protopb/gateway.pb.go b/gateway/protopb/gateway.pb.go
index 571e4298..646508d3 100644
--- a/gateway/protopb/gateway.pb.go
+++ b/gateway/protopb/gateway.pb.go
@@ -78,6 +78,75 @@ func (Strategy) EnumDescriptor() ([]byte, []int) {
 	return file_gateway_proto_rawDescGZIP(), []int{0}
 }
 
+// RequestStatus defines the possible states of a land request.
+type RequestStatus int32
+
+const (
+	// Unknown status. Should never be seen in the system.
+	RequestStatus_UNKNOWN RequestStatus = 0
+	// Initial state of a land request. Confirmed by the system but processing has not started.
+	RequestStatus_NEW RequestStatus = 1
+	// The request has been validated (duplicate check, merge check etc.) successfully.
+	RequestStatus_VALIDATED RequestStatus = 2
+	// The request is being processed.
+	RequestStatus_PROCESSING RequestStatus = 3
+	// The request has been successfully processed and landed. Terminal state.
+	RequestStatus_LANDED RequestStatus = 4
+	// The cancellation request has been accepted and is being processed.
+	RequestStatus_CANCELLATION_ACCEPTED RequestStatus = 5
+	// The request has been cancelled. Terminal state.
+	RequestStatus_CANCELLED RequestStatus = 6
+)
+
+// Enum value maps for RequestStatus.
+var (
+	RequestStatus_name = map[int32]string{
+		0: "UNKNOWN",
+		1: "NEW",
+		2: "VALIDATED",
+		3: "PROCESSING",
+		4: "LANDED",
+		5: "CANCELLATION_ACCEPTED",
+		6: "CANCELLED",
+	}
+	RequestStatus_value = map[string]int32{
+		"UNKNOWN":               0,
+		"NEW":                   1,
+		"VALIDATED":             2,
+		"PROCESSING":            3,
+		"LANDED":                4,
+		"CANCELLATION_ACCEPTED": 5,
+		"CANCELLED":             6,
+	}
+)
+
+func (x RequestStatus) Enum() *RequestStatus {
+	p := new(RequestStatus)
+	*p = x
+	return p
+}
+
+func (x RequestStatus) String() string {
+	return protoimpl.X.EnumStringOf(x.Descriptor(), protoreflect.EnumNumber(x))
+}
+
+func (RequestStatus) Descriptor() protoreflect.EnumDescriptor {
+	return file_gateway_proto_enumTypes[1].Descriptor()
+}
+
+func (RequestStatus) Type() protoreflect.EnumType {
+	return &file_gateway_proto_enumTypes[1]
+}
+
+func (x RequestStatus) Number() protoreflect.EnumNumber {
+	return protoreflect.EnumNumber(x)
+}
+
+// Deprecated: Use RequestStatus.Descriptor instead.
+func (RequestStatus) EnumDescriptor() ([]byte, []int) {
+	return file_gateway_proto_rawDescGZIP(), []int{1}
+}
+
 // PingRequest is the request for the Ping method
 type PingRequest struct {
 	state protoimpl.MessageState `protogen:"open.v1"`
@@ -414,7 +483,11 @@ func (x *CancelRequest) GetSqid() string {
 type CancelResponse struct {
 	state protoimpl.MessageState `protogen:"open.v1"`
 	// Globally unique identifier for the land request that was cancelled.
-	Sqid          string `protobuf:"bytes,1,opt,name=sqid,proto3" json:"sqid,omitempty"`
+	Sqid string `protobuf:"bytes,1,opt,name=sqid,proto3" json:"sqid,omitempty"`
+	// Current status of the land request at the time of cancellation.
+	CurrentStatus RequestStatus `protobuf:"varint,2,opt,name=current_status,json=currentStatus,proto3,enum=uber.devexp.submitqueue.gateway.RequestStatus" json:"current_status,omitempty"`
+	// Optional error describing why the cancellation could not be completed.
+	Error         *Error `protobuf:"bytes,3,opt,name=error,proto3" json:"error,omitempty"`
 	unknownFields protoimpl.UnknownFields
 	sizeCache     protoimpl.SizeCache
 }
@@ -456,6 +529,20 @@ func (x *CancelResponse) GetSqid() string {
 	return ""
 }
 
+func (x *CancelResponse) GetCurrentStatus() RequestStatus {
+	if x != nil {
+		return x.CurrentStatus
+	}
+	return RequestStatus_UNKNOWN
+}
+
+func (x *CancelResponse) GetError() *Error {
+	if x != nil {
+		return x.Error
+	}
+	return nil
+}
+
 // Generic error with metadata. Each custom error type should extend this message.
 type Error struct {
 	state protoimpl.MessageState `protogen:"open.v1"`
@@ -578,9 +665,11 @@ const file_gateway_proto_rawDesc = "" +
 	"\fLandResponse\x12\x12\n" +
 	"\x04sqid\x18\x01 \x01(\tR\x04sqid\"#\n" +
 	"\rCancelRequest\x12\x12\n" +
-	"\x04sqid\x18\x01 \x01(\tR\x04sqid\"$\n" +
+	"\x04sqid\x18\x01 \x01(\tR\x04sqid\"\xb9\x01\n" +
 	"\x0eCancelResponse\x12\x12\n" +
-	"\x04sqid\x18\x01 \x01(\tR\x04sqid\"!\n" +
+	"\x04sqid\x18\x01 \x01(\tR\x04sqid\x12U\n" +
+	"\x0ecurrent_status\x18\x02 \x01(\x0e2..uber.devexp.submitqueue.gateway.RequestStatusR\rcurrentStatus\x12<\n" +
+	"\x05error\x18\x03 \x01(\v2&.uber.devexp.submitqueue.gateway.ErrorR\x05error\"!\n" +
 	"\x05Error\x12\x18\n" +
 	"\amessage\x18\x01 \x01(\tR\amessage\"l\n" +
 	"\x16UnrecognizedQueueError\x12<\n" +
@@ -591,7 +680,17 @@ const file_gateway_proto_rawDesc = "" +
 	"\n" +
 	"\x06REBASE\x10\x01\x12\x11\n" +
 	"\rSQUASH_REBASE\x10\x02\x12\t\n" +
-	"\x05MERGE\x10\x032\xcf\x02\n" +
+	"\x05MERGE\x10\x03*z\n" +
+	"\rRequestStatus\x12\v\n" +
+	"\aUNKNOWN\x10\x00\x12\a\n" +
+	"\x03NEW\x10\x01\x12\r\n" +
+	"\tVALIDATED\x10\x02\x12\x0e\n" +
+	"\n" +
+	"PROCESSING\x10\x03\x12\n" +
+	"\n" +
+	"\x06LANDED\x10\x04\x12\x19\n" +
+	"\x15CANCELLATION_ACCEPTED\x10\x05\x12\r\n" +
+	"\tCANCELLED\x10\x062\xcf\x02\n" +
 	"\x12SubmitQueueGateway\x12e\n" +
 	"\x04Ping\x12,.uber.devexp.submitqueue.gateway.PingRequest\x1a-.uber.devexp.submitqueue.gateway.PingResponse\"\x00\x12e\n" +
 	"\x04Land\x12,.uber.devexp.submitqueue.gateway.LandRequest\x1a-.uber.devexp.submitqueue.gateway.LandResponse\"\x00\x12k\n" +
@@ -610,35 +709,38 @@ func file_gateway_proto_rawDescGZIP() []byte {
 	return file_gateway_proto_rawDescData
 }
 
-var file_gateway_proto_enumTypes = make([]protoimpl.EnumInfo, 1)
+var file_gateway_proto_enumTypes = make([]protoimpl.EnumInfo, 2)
 var file_gateway_proto_msgTypes = make([]protoimpl.MessageInfo, 9)
 var file_gateway_proto_goTypes = []any{
 	(Strategy)(0),                  // 0: uber.devexp.submitqueue.gateway.Strategy
-	(*PingRequest)(nil),            // 1: uber.devexp.submitqueue.gateway.PingRequest
-	(*PingResponse)(nil),           // 2: uber.devexp.submitqueue.gateway.PingResponse
-	(*Change)(nil),                 // 3: uber.devexp.submitqueue.gateway.Change
-	(*LandRequest)(nil),            // 4: uber.devexp.submitqueue.gateway.LandRequest
-	(*LandResponse)(nil),           // 5: uber.devexp.submitqueue.gateway.LandResponse
-	(*CancelRequest)(nil),          // 6: uber.devexp.submitqueue.gateway.CancelRequest
-	(*CancelResponse)(nil),         // 7: uber.devexp.submitqueue.gateway.CancelResponse
-	(*Error)(nil),                  // 8: uber.devexp.submitqueue.gateway.Error
-	(*UnrecognizedQueueError)(nil), // 9: uber.devexp.submitqueue.gateway.UnrecognizedQueueError
+	(RequestStatus)(0),             // 1: uber.devexp.submitqueue.gateway.RequestStatus
+	(*PingRequest)(nil),            // 2: uber.devexp.submitqueue.gateway.PingRequest
+	(*PingResponse)(nil),           // 3: uber.devexp.submitqueue.gateway.PingResponse
+	(*Change)(nil),                 // 4: uber.devexp.submitqueue.gateway.Change
+	(*LandRequest)(nil),            // 5: uber.devexp.submitqueue.gateway.LandRequest
+	(*LandResponse)(nil),           // 6: uber.devexp.submitqueue.gateway.LandResponse
+	(*CancelRequest)(nil),          // 7: uber.devexp.submitqueue.gateway.CancelRequest
+	(*CancelResponse)(nil),         // 8: uber.devexp.submitqueue.gateway.CancelResponse
+	(*Error)(nil),                  // 9: uber.devexp.submitqueue.gateway.Error
+	(*UnrecognizedQueueError)(nil), // 10: uber.devexp.submitqueue.gateway.UnrecognizedQueueError
 }
 var file_gateway_proto_depIdxs = []int32{
-	3, // 0: uber.devexp.submitqueue.gateway.LandRequest.change:type_name -> uber.devexp.submitqueue.gateway.Change
+	4, // 0: uber.devexp.submitqueue.gateway.LandRequest.change:type_name -> uber.devexp.submitqueue.gateway.Change
 	0, // 1: uber.devexp.submitqueue.gateway.LandRequest.strategy:type_name -> uber.devexp.submitqueue.gateway.Strategy
-	8, // 2: uber.devexp.submitqueue.gateway.UnrecognizedQueueError.error:type_name -> uber.devexp.submitqueue.gateway.Error
-	1, // 3: uber.devexp.submitqueue.gateway.SubmitQueueGateway.Ping:input_type -> uber.devexp.submitqueue.gateway.PingRequest
-	4, // 4: uber.devexp.submitqueue.gateway.SubmitQueueGateway.Land:input_type -> uber.devexp.submitqueue.gateway.LandRequest
-	6, // 5: uber.devexp.submitqueue.gateway.SubmitQueueGateway.Cancel:input_type -> uber.devexp.submitqueue.gateway.CancelRequest
-	2, // 6: uber.devexp.submitqueue.gateway.SubmitQueueGateway.Ping:output_type -> uber.devexp.submitqueue.gateway.PingResponse
-	5, // 7: uber.devexp.submitqueue.gateway.SubmitQueueGateway.Land:output_type -> uber.devexp.submitqueue.gateway.LandResponse
-	7, // 8: uber.devexp.submitqueue.gateway.SubmitQueueGateway.Cancel:output_type -> uber.devexp.submitqueue.gateway.CancelResponse
-	6, // [6:9] is the sub-list for method output_type
-	3, // [3:6] is the sub-list for method input_type
-	3, // [3:3] is the sub-list for extension type_name
-	3, // [3:3] is the sub-list for extension extendee
-	0, // [0:3] is the sub-list for field type_name
+	1, // 2: uber.devexp.submitqueue.gateway.CancelResponse.current_status:type_name -> uber.devexp.submitqueue.gateway.RequestStatus
+	9, // 3: uber.devexp.submitqueue.gateway.CancelResponse.error:type_name -> uber.devexp.submitqueue.gateway.Error
+	9, // 4: uber.devexp.submitqueue.gateway.UnrecognizedQueueError.error:type_name -> uber.devexp.submitqueue.gateway.Error
+	2, // 5: uber.devexp.submitqueue.gateway.SubmitQueueGateway.Ping:input_type -> uber.devexp.submitqueue.gateway.PingRequest
+	5, // 6: uber.devexp.submitqueue.gateway.SubmitQueueGateway.Land:input_type -> uber.devexp.submitqueue.gateway.LandRequest
+	7, // 7: uber.devexp.submitqueue.gateway.SubmitQueueGateway.Cancel:input_type -> uber.devexp.submitqueue.gateway.CancelRequest
+	3, // 8: uber.devexp.submitqueue.gateway.SubmitQueueGateway.Ping:output_type -> uber.devexp.submitqueue.gateway.PingResponse
+	6, // 9: uber.devexp.submitqueue.gateway.SubmitQueueGateway.Land:output_type -> uber.devexp.submitqueue.gateway.LandResponse
+	8, // 10: uber.devexp.submitqueue.gateway.SubmitQueueGateway.Cancel:output_type -> uber.devexp.submitqueue.gateway.CancelResponse
+	8, // [8:11] is the sub-list for method output_type
+	5, // [5:8] is the sub-list for method input_type
+	5, // [5:5] is the sub-list for extension type_name
+	5, // [5:5] is the sub-list for extension extendee
+	0, // [0:5] is the sub-list for field type_name
 }
 
 func init() { file_gateway_proto_init() }
@@ -651,7 +753,7 @@ func file_gateway_proto_init() {
 		File: protoimpl.DescBuilder{
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: unsafe.Slice(unsafe.StringData(file_gateway_proto_rawDesc), len(file_gateway_proto_rawDesc)),
-			NumEnums:      1,
+			NumEnums:      2,
 			NumMessages:   9,
 			NumExtensions: 0,
 			NumServices:   1,
diff --git a/gateway/protopb/gateway.pb.yarpc.go b/gateway/protopb/gateway.pb.yarpc.go
index ca8b152c..dc18521d 100644
--- a/gateway/protopb/gateway.pb.yarpc.go
+++ b/gateway/protopb/gateway.pb.yarpc.go
@@ -333,39 +333,47 @@ var (
 var yarpcFileDescriptorClosuref1a937782ebbded5 = [][]byte{
 	// gateway.proto
 	[]byte{
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+		0x5a, 0x17, 0x87, 0xd7, 0xbf, 0x03, 0x00, 0x00, 0xff, 0xff, 0xf7, 0x64, 0x71, 0x91, 0xc0, 0x05,
+		0x00, 0x00,
 	},
 }
 
diff --git a/gateway/protopb/gateway_grpc.pb.go b/gateway/protopb/gateway_grpc.pb.go
index 695ba3bc..5eef2770 100644
--- a/gateway/protopb/gateway_grpc.pb.go
+++ b/gateway/protopb/gateway_grpc.pb.go
@@ -35,8 +35,12 @@ type SubmitQueueGatewayClient interface {
 	// Land lands a set of code changes into a target branch, performing the necessary validations across all other changes in the queue.
 	// The processing is asynchronous and returns a LandResponse immediately. The land request is processed in the background.
 	Land(ctx context.Context, in *LandRequest, opts ...grpc.CallOption) (*LandResponse, error)
-	// Cancel cancels a previously submitted land request. The cancellation is asynchronous and
-	// published to a queue for processing. No validation is performed on whether the request exists.
+	// Cancel requests cancellation of a previously submitted land request.
+	// The cancellation is asynchronous and published to a queue for
+	// processing. Note that cancellation is best effort and not guaranteed.
+	// To check for the status of the request, use Status API (TODO). A
+	// "Cancelled" status indicates that the requested cancellation was
+	// successful.
 	Cancel(ctx context.Context, in *CancelRequest, opts ...grpc.CallOption) (*CancelResponse, error)
 }
 
@@ -89,8 +93,12 @@ type SubmitQueueGatewayServer interface {
 	// Land lands a set of code changes into a target branch, performing the necessary validations across all other changes in the queue.
 	// The processing is asynchronous and returns a LandResponse immediately. The land request is processed in the background.
 	Land(context.Context, *LandRequest) (*LandResponse, error)
-	// Cancel cancels a previously submitted land request. The cancellation is asynchronous and
-	// published to a queue for processing. No validation is performed on whether the request exists.
+	// Cancel requests cancellation of a previously submitted land request.
+	// The cancellation is asynchronous and published to a queue for
+	// processing. Note that cancellation is best effort and not guaranteed.
+	// To check for the status of the request, use Status API (TODO). A
+	// "Cancelled" status indicates that the requested cancellation was
+	// successful.
 	Cancel(context.Context, *CancelRequest) (*CancelResponse, error)
 	mustEmbedUnimplementedSubmitQueueGatewayServer()
 }