diff --git a/runway/extension/BUILD.bazel b/runway/extension/BUILD.bazel
new file mode 100644
index 00000000..3832145f
--- /dev/null
+++ b/runway/extension/BUILD.bazel
@@ -0,0 +1,8 @@
+load("@rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "extension",
+    srcs = ["extension.go"],
+    importpath = "github.com/uber/submitqueue/runway/extension",
+    visibility = ["//visibility:public"],
+)
diff --git a/runway/extension/extension.go b/runway/extension/extension.go
new file mode 100644
index 00000000..310bab4e
--- /dev/null
+++ b/runway/extension/extension.go
@@ -0,0 +1,16 @@
+// Copyright (c) 2025 Uber Technologies, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package extension holds Runway-specific extension implementations.
+package extension
diff --git a/runway/extension/vcs/BUILD.bazel b/runway/extension/vcs/BUILD.bazel
new file mode 100644
index 00000000..e8e37e16
--- /dev/null
+++ b/runway/extension/vcs/BUILD.bazel
@@ -0,0 +1,9 @@
+load("@rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "vcs",
+    srcs = ["vcs.go"],
+    importpath = "github.com/uber/submitqueue/runway/extension/vcs",
+    visibility = ["//visibility:public"],
+    deps = ["//runway/entity"],
+)
diff --git a/runway/extension/vcs/mock/BUILD.bazel b/runway/extension/vcs/mock/BUILD.bazel
new file mode 100644
index 00000000..e04292b8
--- /dev/null
+++ b/runway/extension/vcs/mock/BUILD.bazel
@@ -0,0 +1,13 @@
+load("@rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "mock",
+    srcs = ["vcs_mock.go"],
+    importpath = "github.com/uber/submitqueue/runway/extension/vcs/mock",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//runway/entity",
+        "//runway/extension/vcs",
+        "@org_uber_go_mock//gomock",
+    ],
+)
diff --git a/runway/extension/vcs/mock/vcs_mock.go b/runway/extension/vcs/mock/vcs_mock.go
new file mode 100644
index 00000000..c4e33cc5
--- /dev/null
+++ b/runway/extension/vcs/mock/vcs_mock.go
@@ -0,0 +1,112 @@
+// Code generated by MockGen. DO NOT EDIT.
+// Source: vcs.go
+//
+// Generated by this command:
+//
+//	mockgen -source=vcs.go -destination=mock/vcs_mock.go -package=mock
+//
+
+// Package mock is a generated GoMock package.
+package mock
+
+import (
+	context "context"
+	reflect "reflect"
+
+	entity "github.com/uber/submitqueue/runway/entity"
+	vcs "github.com/uber/submitqueue/runway/extension/vcs"
+	gomock "go.uber.org/mock/gomock"
+)
+
+// MockVCS is a mock of VCS interface.
+type MockVCS struct {
+	ctrl     *gomock.Controller
+	recorder *MockVCSMockRecorder
+	isgomock struct{}
+}
+
+// MockVCSMockRecorder is the mock recorder for MockVCS.
+type MockVCSMockRecorder struct {
+	mock *MockVCS
+}
+
+// NewMockVCS creates a new mock instance.
+func NewMockVCS(ctrl *gomock.Controller) *MockVCS {
+	mock := &MockVCS{ctrl: ctrl}
+	mock.recorder = &MockVCSMockRecorder{mock}
+	return mock
+}
+
+// EXPECT returns an object that allows the caller to indicate expected use.
+func (m *MockVCS) EXPECT() *MockVCSMockRecorder {
+	return m.recorder
+}
+
+// CheckMergeability mocks base method.
+func (m *MockVCS) CheckMergeability(ctx context.Context, req entity.MergeRequest) (entity.MergeResult, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "CheckMergeability", ctx, req)
+	ret0, _ := ret[0].(entity.MergeResult)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// CheckMergeability indicates an expected call of CheckMergeability.
+func (mr *MockVCSMockRecorder) CheckMergeability(ctx, req any) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "CheckMergeability", reflect.TypeOf((*MockVCS)(nil).CheckMergeability), ctx, req)
+}
+
+// Land mocks base method.
+func (m *MockVCS) Land(ctx context.Context, req entity.MergeRequest) (entity.MergeResult, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "Land", ctx, req)
+	ret0, _ := ret[0].(entity.MergeResult)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// Land indicates an expected call of Land.
+func (mr *MockVCSMockRecorder) Land(ctx, req any) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Land", reflect.TypeOf((*MockVCS)(nil).Land), ctx, req)
+}
+
+// MockFactory is a mock of Factory interface.
+type MockFactory struct {
+	ctrl     *gomock.Controller
+	recorder *MockFactoryMockRecorder
+	isgomock struct{}
+}
+
+// MockFactoryMockRecorder is the mock recorder for MockFactory.
+type MockFactoryMockRecorder struct {
+	mock *MockFactory
+}
+
+// NewMockFactory creates a new mock instance.
+func NewMockFactory(ctrl *gomock.Controller) *MockFactory {
+	mock := &MockFactory{ctrl: ctrl}
+	mock.recorder = &MockFactoryMockRecorder{mock}
+	return mock
+}
+
+// EXPECT returns an object that allows the caller to indicate expected use.
+func (m *MockFactory) EXPECT() *MockFactoryMockRecorder {
+	return m.recorder
+}
+
+// For mocks base method.
+func (m *MockFactory) For(cfg vcs.Config) (vcs.VCS, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "For", cfg)
+	ret0, _ := ret[0].(vcs.VCS)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// For indicates an expected call of For.
+func (mr *MockFactoryMockRecorder) For(cfg any) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "For", reflect.TypeOf((*MockFactory)(nil).For), cfg)
+}
diff --git a/runway/extension/vcs/noop/BUILD.bazel b/runway/extension/vcs/noop/BUILD.bazel
new file mode 100644
index 00000000..b9755204
--- /dev/null
+++ b/runway/extension/vcs/noop/BUILD.bazel
@@ -0,0 +1,25 @@
+load("@rules_go//go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "noop",
+    srcs = ["noop.go"],
+    importpath = "github.com/uber/submitqueue/runway/extension/vcs/noop",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//runway/entity",
+        "//runway/extension/vcs",
+    ],
+)
+
+go_test(
+    name = "noop_test",
+    srcs = ["noop_test.go"],
+    embed = [":noop"],
+    deps = [
+        "//platform/base/change",
+        "//platform/base/mergestrategy",
+        "//runway/entity",
+        "@com_github_stretchr_testify//assert",
+        "@com_github_stretchr_testify//require",
+    ],
+)
diff --git a/runway/extension/vcs/noop/noop.go b/runway/extension/vcs/noop/noop.go
new file mode 100644
index 00000000..cab7dd9b
--- /dev/null
+++ b/runway/extension/vcs/noop/noop.go
@@ -0,0 +1,65 @@
+// Copyright (c) 2025 Uber Technologies, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package noop provides a no-op VCS implementation for local development and
+// testing. CheckMergeability always reports success; Land produces synthetic
+// output IDs from an atomic counter.
+package noop
+
+import (
+	"context"
+	"fmt"
+	"sync/atomic"
+
+	"github.com/uber/submitqueue/runway/entity"
+	"github.com/uber/submitqueue/runway/extension/vcs"
+)
+
+var _ vcs.VCS = (*VCS)(nil)
+
+// VCS is a no-op implementation that always succeeds.
+type VCS struct {
+	seq atomic.Uint64
+}
+
+// New returns a new no-op VCS instance.
+func New() *VCS { return &VCS{} }
+
+func (v *VCS) CheckMergeability(_ context.Context, req entity.MergeRequest) (entity.MergeResult, error) {
+	steps := make([]entity.StepResult, len(req.Steps))
+	for i, s := range req.Steps {
+		steps[i] = entity.StepResult{StepID: s.StepID}
+	}
+	return entity.MergeResult{
+		ID:      req.ID,
+		Success: true,
+		Steps:   steps,
+	}, nil
+}
+
+func (v *VCS) Land(_ context.Context, req entity.MergeRequest) (entity.MergeResult, error) {
+	steps := make([]entity.StepResult, len(req.Steps))
+	for i, s := range req.Steps {
+		n := v.seq.Add(1)
+		steps[i] = entity.StepResult{
+			StepID:    s.StepID,
+			OutputIDs: []string{fmt.Sprintf("%040x", n)},
+		}
+	}
+	return entity.MergeResult{
+		ID:      req.ID,
+		Success: true,
+		Steps:   steps,
+	}, nil
+}
diff --git a/runway/extension/vcs/noop/noop_test.go b/runway/extension/vcs/noop/noop_test.go
new file mode 100644
index 00000000..0137d82e
--- /dev/null
+++ b/runway/extension/vcs/noop/noop_test.go
@@ -0,0 +1,91 @@
+// Copyright (c) 2025 Uber Technologies, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package noop
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"github.com/uber/submitqueue/platform/base/change"
+	"github.com/uber/submitqueue/platform/base/mergestrategy"
+	"github.com/uber/submitqueue/runway/entity"
+)
+
+func testRequest() entity.MergeRequest {
+	return entity.MergeRequest{
+		ID:        "queue-a/42",
+		QueueName: "queue-a",
+		Steps: []entity.MergeStep{
+			{
+				StepID:   "queue-a/1",
+				Changes:  []change.Change{{URIs: []string{"github://uber/repo/pull/1/abcdef0123456789abcdef0123456789abcdef01"}}},
+				Strategy: mergestrategy.MergeStrategyRebase,
+			},
+			{
+				StepID:   "queue-a/2",
+				Changes:  []change.Change{{URIs: []string{"github://uber/repo/pull/2/89abcdef0123456789abcdef0123456789abcdef"}}},
+				Strategy: mergestrategy.MergeStrategyMerge,
+			},
+		},
+	}
+}
+
+func TestCheckMergeability(t *testing.T) {
+	v := New()
+	req := testRequest()
+
+	res, err := v.CheckMergeability(context.Background(), req)
+	require.NoError(t, err)
+
+	assert.Equal(t, req.ID, res.ID)
+	assert.True(t, res.Success)
+	require.Len(t, res.Steps, 2)
+	assert.Equal(t, "queue-a/1", res.Steps[0].StepID)
+	assert.Empty(t, res.Steps[0].OutputIDs)
+	assert.Equal(t, "queue-a/2", res.Steps[1].StepID)
+	assert.Empty(t, res.Steps[1].OutputIDs)
+}
+
+func TestLand(t *testing.T) {
+	v := New()
+	req := testRequest()
+
+	res, err := v.Land(context.Background(), req)
+	require.NoError(t, err)
+
+	assert.Equal(t, req.ID, res.ID)
+	assert.True(t, res.Success)
+	require.Len(t, res.Steps, 2)
+	assert.Equal(t, "queue-a/1", res.Steps[0].StepID)
+	require.Len(t, res.Steps[0].OutputIDs, 1)
+	assert.NotEmpty(t, res.Steps[0].OutputIDs[0])
+	assert.Equal(t, "queue-a/2", res.Steps[1].StepID)
+	require.Len(t, res.Steps[1].OutputIDs, 1)
+	assert.NotEmpty(t, res.Steps[1].OutputIDs[0])
+}
+
+func TestLand_UniqueOutputIDs(t *testing.T) {
+	v := New()
+	req := testRequest()
+
+	res1, err := v.Land(context.Background(), req)
+	require.NoError(t, err)
+	res2, err := v.Land(context.Background(), req)
+	require.NoError(t, err)
+
+	assert.NotEqual(t, res1.Steps[0].OutputIDs[0], res2.Steps[0].OutputIDs[0])
+}
diff --git a/runway/extension/vcs/vcs.go b/runway/extension/vcs/vcs.go
new file mode 100644
index 00000000..061ada28
--- /dev/null
+++ b/runway/extension/vcs/vcs.go
@@ -0,0 +1,58 @@
+// Copyright (c) 2025 Uber Technologies, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package vcs defines the pluggable interface for version-control operations
+// that Runway performs on behalf of its callers. Implementations resolve change
+// URIs, apply changes to a target branch, and (for a committing merge) push the
+// result and finalize the change lifecycle (e.g. close PRs).
+package vcs
+
+//go:generate mockgen -source=vcs.go -destination=mock/vcs_mock.go -package=mock
+
+import (
+	"context"
+	"errors"
+
+	"github.com/uber/submitqueue/runway/entity"
+)
+
+// ErrConflict signals that the ordered steps could not be applied cleanly.
+// Controllers treat this as an expected outcome (ack + publish a failure
+// result), not an infrastructure error.
+var ErrConflict = errors.New("merge conflict")
+
+// VCS performs version-control operations against a single landing target.
+// Both methods accept the same MergeRequest payload; the behavioral difference
+// is whether the result is committed to the remote.
+type VCS interface {
+	// CheckMergeability performs a dry-run merge without committing. The
+	// returned MergeResult reports per-step mergeability; OutputIDs are empty.
+	CheckMergeability(ctx context.Context, req entity.MergeRequest) (entity.MergeResult, error)
+	// Land applies the ordered steps, commits the result to the remote, and
+	// reports per-step OutputIDs (the VCS-neutral revision identifiers produced).
+	Land(ctx context.Context, req entity.MergeRequest) (entity.MergeResult, error)
+}
+
+// Config identifies the landing target a VCS instance operates on. The factory
+// resolves deployment-specific details (remote URL, credentials) from this.
+type Config struct {
+	// QueueName is the caller-provided queue name from the MergeRequest.
+	QueueName string
+}
+
+// Factory creates VCS instances bound to a landing target.
+type Factory interface {
+	// For returns a VCS instance configured for the given landing target.
+	For(cfg Config) (VCS, error)
+}