diff --git a/stovepipe/extension/storage/BUILD.bazel b/stovepipe/extension/storage/BUILD.bazel
new file mode 100644
index 00000000..15ee8578
--- /dev/null
+++ b/stovepipe/extension/storage/BUILD.bazel
@@ -0,0 +1,13 @@
+load("@rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "storage",
+    srcs = [
+        "request_store.go",
+        "request_uri_store.go",
+        "storage.go",
+    ],
+    importpath = "github.com/uber/submitqueue/stovepipe/extension/storage",
+    visibility = ["//visibility:public"],
+    deps = ["//stovepipe/entity"],
+)
diff --git a/stovepipe/extension/storage/mock/BUILD.bazel b/stovepipe/extension/storage/mock/BUILD.bazel
new file mode 100644
index 00000000..c82888ad
--- /dev/null
+++ b/stovepipe/extension/storage/mock/BUILD.bazel
@@ -0,0 +1,17 @@
+load("@rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "mock",
+    srcs = [
+        "request_store_mock.go",
+        "request_uri_store_mock.go",
+        "storage_mock.go",
+    ],
+    importpath = "github.com/uber/submitqueue/stovepipe/extension/storage/mock",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//stovepipe/entity",
+        "//stovepipe/extension/storage",
+        "@org_uber_go_mock//gomock",
+    ],
+)
diff --git a/stovepipe/extension/storage/mock/request_store_mock.go b/stovepipe/extension/storage/mock/request_store_mock.go
new file mode 100644
index 00000000..089ae8a1
--- /dev/null
+++ b/stovepipe/extension/storage/mock/request_store_mock.go
@@ -0,0 +1,85 @@
+// Code generated by MockGen. DO NOT EDIT.
+// Source: request_store.go
+//
+// Generated by this command:
+//
+//	mockgen -source=request_store.go -destination=mock/request_store_mock.go -package=mock
+//
+
+// Package mock is a generated GoMock package.
+package mock
+
+import (
+	context "context"
+	reflect "reflect"
+
+	entity "github.com/uber/submitqueue/stovepipe/entity"
+	gomock "go.uber.org/mock/gomock"
+)
+
+// MockRequestStore is a mock of RequestStore interface.
+type MockRequestStore struct {
+	ctrl     *gomock.Controller
+	recorder *MockRequestStoreMockRecorder
+	isgomock struct{}
+}
+
+// MockRequestStoreMockRecorder is the mock recorder for MockRequestStore.
+type MockRequestStoreMockRecorder struct {
+	mock *MockRequestStore
+}
+
+// NewMockRequestStore creates a new mock instance.
+func NewMockRequestStore(ctrl *gomock.Controller) *MockRequestStore {
+	mock := &MockRequestStore{ctrl: ctrl}
+	mock.recorder = &MockRequestStoreMockRecorder{mock}
+	return mock
+}
+
+// EXPECT returns an object that allows the caller to indicate expected use.
+func (m *MockRequestStore) EXPECT() *MockRequestStoreMockRecorder {
+	return m.recorder
+}
+
+// Create mocks base method.
+func (m *MockRequestStore) Create(ctx context.Context, request entity.Request) error {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "Create", ctx, request)
+	ret0, _ := ret[0].(error)
+	return ret0
+}
+
+// Create indicates an expected call of Create.
+func (mr *MockRequestStoreMockRecorder) Create(ctx, request any) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Create", reflect.TypeOf((*MockRequestStore)(nil).Create), ctx, request)
+}
+
+// Get mocks base method.
+func (m *MockRequestStore) Get(ctx context.Context, id string) (entity.Request, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "Get", ctx, id)
+	ret0, _ := ret[0].(entity.Request)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// Get indicates an expected call of Get.
+func (mr *MockRequestStoreMockRecorder) Get(ctx, id any) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Get", reflect.TypeOf((*MockRequestStore)(nil).Get), ctx, id)
+}
+
+// Update mocks base method.
+func (m *MockRequestStore) Update(ctx context.Context, request entity.Request, oldVersion, newVersion int32) error {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "Update", ctx, request, oldVersion, newVersion)
+	ret0, _ := ret[0].(error)
+	return ret0
+}
+
+// Update indicates an expected call of Update.
+func (mr *MockRequestStoreMockRecorder) Update(ctx, request, oldVersion, newVersion any) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Update", reflect.TypeOf((*MockRequestStore)(nil).Update), ctx, request, oldVersion, newVersion)
+}
diff --git a/stovepipe/extension/storage/mock/request_uri_store_mock.go b/stovepipe/extension/storage/mock/request_uri_store_mock.go
new file mode 100644
index 00000000..e50bf237
--- /dev/null
+++ b/stovepipe/extension/storage/mock/request_uri_store_mock.go
@@ -0,0 +1,70 @@
+// Code generated by MockGen. DO NOT EDIT.
+// Source: request_uri_store.go
+//
+// Generated by this command:
+//
+//	mockgen -source=request_uri_store.go -destination=mock/request_uri_store_mock.go -package=mock
+//
+
+// Package mock is a generated GoMock package.
+package mock
+
+import (
+	context "context"
+	reflect "reflect"
+
+	gomock "go.uber.org/mock/gomock"
+)
+
+// MockRequestURIStore is a mock of RequestURIStore interface.
+type MockRequestURIStore struct {
+	ctrl     *gomock.Controller
+	recorder *MockRequestURIStoreMockRecorder
+	isgomock struct{}
+}
+
+// MockRequestURIStoreMockRecorder is the mock recorder for MockRequestURIStore.
+type MockRequestURIStoreMockRecorder struct {
+	mock *MockRequestURIStore
+}
+
+// NewMockRequestURIStore creates a new mock instance.
+func NewMockRequestURIStore(ctrl *gomock.Controller) *MockRequestURIStore {
+	mock := &MockRequestURIStore{ctrl: ctrl}
+	mock.recorder = &MockRequestURIStoreMockRecorder{mock}
+	return mock
+}
+
+// EXPECT returns an object that allows the caller to indicate expected use.
+func (m *MockRequestURIStore) EXPECT() *MockRequestURIStoreMockRecorder {
+	return m.recorder
+}
+
+// Create mocks base method.
+func (m *MockRequestURIStore) Create(ctx context.Context, queue, uri, id string) error {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "Create", ctx, queue, uri, id)
+	ret0, _ := ret[0].(error)
+	return ret0
+}
+
+// Create indicates an expected call of Create.
+func (mr *MockRequestURIStoreMockRecorder) Create(ctx, queue, uri, id any) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Create", reflect.TypeOf((*MockRequestURIStore)(nil).Create), ctx, queue, uri, id)
+}
+
+// GetIDByURI mocks base method.
+func (m *MockRequestURIStore) GetIDByURI(ctx context.Context, queue, uri string) (string, error) {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "GetIDByURI", ctx, queue, uri)
+	ret0, _ := ret[0].(string)
+	ret1, _ := ret[1].(error)
+	return ret0, ret1
+}
+
+// GetIDByURI indicates an expected call of GetIDByURI.
+func (mr *MockRequestURIStoreMockRecorder) GetIDByURI(ctx, queue, uri any) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetIDByURI", reflect.TypeOf((*MockRequestURIStore)(nil).GetIDByURI), ctx, queue, uri)
+}
diff --git a/stovepipe/extension/storage/mock/storage_mock.go b/stovepipe/extension/storage/mock/storage_mock.go
new file mode 100644
index 00000000..7da8ebb9
--- /dev/null
+++ b/stovepipe/extension/storage/mock/storage_mock.go
@@ -0,0 +1,83 @@
+// Code generated by MockGen. DO NOT EDIT.
+// Source: storage.go
+//
+// Generated by this command:
+//
+//	mockgen -source=storage.go -destination=mock/storage_mock.go -package=mock
+//
+
+// Package mock is a generated GoMock package.
+package mock
+
+import (
+	reflect "reflect"
+
+	storage "github.com/uber/submitqueue/stovepipe/extension/storage"
+	gomock "go.uber.org/mock/gomock"
+)
+
+// MockStorage is a mock of Storage interface.
+type MockStorage struct {
+	ctrl     *gomock.Controller
+	recorder *MockStorageMockRecorder
+	isgomock struct{}
+}
+
+// MockStorageMockRecorder is the mock recorder for MockStorage.
+type MockStorageMockRecorder struct {
+	mock *MockStorage
+}
+
+// NewMockStorage creates a new mock instance.
+func NewMockStorage(ctrl *gomock.Controller) *MockStorage {
+	mock := &MockStorage{ctrl: ctrl}
+	mock.recorder = &MockStorageMockRecorder{mock}
+	return mock
+}
+
+// EXPECT returns an object that allows the caller to indicate expected use.
+func (m *MockStorage) EXPECT() *MockStorageMockRecorder {
+	return m.recorder
+}
+
+// Close mocks base method.
+func (m *MockStorage) Close() error {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "Close")
+	ret0, _ := ret[0].(error)
+	return ret0
+}
+
+// Close indicates an expected call of Close.
+func (mr *MockStorageMockRecorder) Close() *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "Close", reflect.TypeOf((*MockStorage)(nil).Close))
+}
+
+// GetRequestStore mocks base method.
+func (m *MockStorage) GetRequestStore() storage.RequestStore {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "GetRequestStore")
+	ret0, _ := ret[0].(storage.RequestStore)
+	return ret0
+}
+
+// GetRequestStore indicates an expected call of GetRequestStore.
+func (mr *MockStorageMockRecorder) GetRequestStore() *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetRequestStore", reflect.TypeOf((*MockStorage)(nil).GetRequestStore))
+}
+
+// GetRequestURIStore mocks base method.
+func (m *MockStorage) GetRequestURIStore() storage.RequestURIStore {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "GetRequestURIStore")
+	ret0, _ := ret[0].(storage.RequestURIStore)
+	return ret0
+}
+
+// GetRequestURIStore indicates an expected call of GetRequestURIStore.
+func (mr *MockStorageMockRecorder) GetRequestURIStore() *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "GetRequestURIStore", reflect.TypeOf((*MockStorage)(nil).GetRequestURIStore))
+}
diff --git a/stovepipe/extension/storage/mysql/BUILD.bazel b/stovepipe/extension/storage/mysql/BUILD.bazel
new file mode 100644
index 00000000..2ec40caf
--- /dev/null
+++ b/stovepipe/extension/storage/mysql/BUILD.bazel
@@ -0,0 +1,19 @@
+load("@rules_go//go:def.bzl", "go_library")
+
+go_library(
+    name = "mysql",
+    srcs = [
+        "request_store.go",
+        "request_uri_store.go",
+        "storage.go",
+    ],
+    importpath = "github.com/uber/submitqueue/stovepipe/extension/storage/mysql",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//platform/metrics",
+        "//stovepipe/entity",
+        "//stovepipe/extension/storage",
+        "@com_github_go_sql_driver_mysql//:mysql",
+        "@com_github_uber_go_tally//:tally",
+    ],
+)
diff --git a/stovepipe/extension/storage/mysql/request_store.go b/stovepipe/extension/storage/mysql/request_store.go
new file mode 100644
index 00000000..f9573d84
--- /dev/null
+++ b/stovepipe/extension/storage/mysql/request_store.go
@@ -0,0 +1,126 @@
+// 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 mysql
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"fmt"
+
+	"github.com/go-sql-driver/mysql"
+	"github.com/uber-go/tally"
+
+	"github.com/uber/submitqueue/platform/metrics"
+	"github.com/uber/submitqueue/stovepipe/entity"
+	"github.com/uber/submitqueue/stovepipe/extension/storage"
+)
+
+// mysqlErrDuplicateEntry is MySQL error code 1062 ("Duplicate entry"), returned on a unique/primary
+// key violation. It requires a unique index on the table to be raised.
+const mysqlErrDuplicateEntry = 1062
+
+type requestStore struct {
+	db    *sql.DB
+	scope tally.Scope
+}
+
+// NewRequestStore creates a new MySQL-backed RequestStore.
+func NewRequestStore(db *sql.DB, scope tally.Scope) storage.RequestStore {
+	return &requestStore{db: db, scope: scope}
+}
+
+// Create persists a new request. Returns ErrAlreadyExists if the request ID already exists.
+func (r *requestStore) Create(ctx context.Context, request entity.Request) (retErr error) {
+	op := metrics.Begin(r.scope, "create")
+	defer func() { op.Complete(retErr) }()
+
+	_, err := r.db.ExecContext(ctx,
+		"INSERT INTO request (id, queue, uri, state, version) VALUES (?, ?, ?, ?, ?)",
+		request.ID, request.Queue, request.URI, request.State, request.Version,
+	)
+	if err != nil {
+		if isDuplicateEntry(err) {
+			return fmt.Errorf("request entity id=%s: %w", request.ID, storage.ErrAlreadyExists)
+		}
+		return fmt.Errorf("failed to insert request entity id=%s: %w", request.ID, err)
+	}
+
+	return nil
+}
+
+// Get retrieves a request by ID. Returns ErrNotFound if the request is not found.
+func (r *requestStore) Get(ctx context.Context, id string) (ret entity.Request, retErr error) {
+	op := metrics.Begin(r.scope, "get")
+	defer func() { op.Complete(retErr) }()
+
+	var req entity.Request
+	err := r.db.QueryRowContext(ctx,
+		"SELECT id, queue, uri, state, version FROM request WHERE id = ?",
+		id,
+	).Scan(&req.ID, &req.Queue, &req.URI, &req.State, &req.Version)
+
+	if errors.Is(err, sql.ErrNoRows) {
+		return entity.Request{}, storage.WrapNotFound(err)
+	}
+	if err != nil {
+		return entity.Request{}, fmt.Errorf("failed to get request entity id=%s from the database: %w", id, err)
+	}
+
+	return req, nil
+}
+
+// Update persists the mutable fields of request (uri, state) if the stored version matches
+// oldVersion, writing newVersion. Returns ErrVersionMismatch if the stored version does not match
+// (including when the request does not exist). This is a pure conditional write; the caller owns
+// version arithmetic.
+func (r *requestStore) Update(ctx context.Context, request entity.Request, oldVersion, newVersion int32) (retErr error) {
+	op := metrics.Begin(r.scope, "update")
+	defer func() { op.Complete(retErr) }()
+
+	result, err := r.db.ExecContext(ctx,
+		"UPDATE request SET uri = ?, state = ?, version = ? WHERE id = ? AND version = ?",
+		request.URI, request.State, newVersion, request.ID, oldVersion,
+	)
+	if err != nil {
+		return fmt.Errorf(
+			"failed to update request id=%q oldVersion=%d newVersion=%d: %w",
+			request.ID, oldVersion, newVersion, err,
+		)
+	}
+
+	rowsAffected, err := result.RowsAffected()
+	if err != nil {
+		return fmt.Errorf(
+			"failed to get rows affected from update for id=%q oldVersion=%d newVersion=%d: %w",
+			request.ID, oldVersion, newVersion, err,
+		)
+	}
+
+	if rowsAffected != 1 {
+		return fmt.Errorf(
+			"version mismatch for request update: id=%q expected_version=%d: %w",
+			request.ID, oldVersion, storage.ErrVersionMismatch,
+		)
+	}
+
+	return nil
+}
+
+// isDuplicateEntry reports whether err is a MySQL duplicate-key (1062) error.
+func isDuplicateEntry(err error) bool {
+	var mysqlErr *mysql.MySQLError
+	return errors.As(err, &mysqlErr) && mysqlErr.Number == mysqlErrDuplicateEntry
+}
diff --git a/stovepipe/extension/storage/mysql/request_uri_store.go b/stovepipe/extension/storage/mysql/request_uri_store.go
new file mode 100644
index 00000000..1f5c5aea
--- /dev/null
+++ b/stovepipe/extension/storage/mysql/request_uri_store.go
@@ -0,0 +1,83 @@
+// 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 mysql
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"fmt"
+
+	"github.com/uber-go/tally"
+
+	"github.com/uber/submitqueue/platform/metrics"
+	"github.com/uber/submitqueue/stovepipe/extension/storage"
+)
+
+// requestURIInitialVersion is the version written for a new mapping. The mapping is insert-once,
+// so the column is constant today; it exists for record consistency with the other stores and to
+// reserve optimistic-locking semantics if the mapping ever becomes mutable.
+const requestURIInitialVersion = 1
+
+type requestURIStore struct {
+	db    *sql.DB
+	scope tally.Scope
+}
+
+// NewRequestURIStore creates a new MySQL-backed RequestURIStore.
+func NewRequestURIStore(db *sql.DB, scope tally.Scope) storage.RequestURIStore {
+	return &requestURIStore{db: db, scope: scope}
+}
+
+// Create records the (queue, uri) -> id reverse index. Returns ErrAlreadyExists if (queue, uri)
+// is already mapped to a request.
+func (r *requestURIStore) Create(ctx context.Context, queue, uri, id string) (retErr error) {
+	op := metrics.Begin(r.scope, "create")
+	defer func() { op.Complete(retErr) }()
+
+	_, err := r.db.ExecContext(ctx,
+		"INSERT INTO request_uri (queue, uri, request_id, version) VALUES (?, ?, ?, ?)",
+		queue, uri, id, requestURIInitialVersion,
+	)
+	if err != nil {
+		if isDuplicateEntry(err) {
+			return fmt.Errorf("request_uri queue=%s uri=%s: %w", queue, uri, storage.ErrAlreadyExists)
+		}
+		return fmt.Errorf("failed to map queue=%s uri=%s to request id=%s: %w", queue, uri, id, err)
+	}
+
+	return nil
+}
+
+// GetIDByURI returns the id of the request validating (queue, uri). Returns ErrNotFound if absent.
+func (r *requestURIStore) GetIDByURI(ctx context.Context, queue, uri string) (ret string, retErr error) {
+	op := metrics.Begin(r.scope, "get_id_by_uri")
+	defer func() { op.Complete(retErr) }()
+
+	var id string
+	err := r.db.QueryRowContext(ctx,
+		"SELECT request_id FROM request_uri WHERE queue = ? AND uri = ?",
+		queue, uri,
+	).Scan(&id)
+
+	if errors.Is(err, sql.ErrNoRows) {
+		return "", storage.WrapNotFound(err)
+	}
+	if err != nil {
+		return "", fmt.Errorf("failed to get request id for queue=%s uri=%s from the database: %w", queue, uri, err)
+	}
+
+	return id, nil
+}
diff --git a/stovepipe/extension/storage/mysql/schema/BUILD.bazel b/stovepipe/extension/storage/mysql/schema/BUILD.bazel
new file mode 100644
index 00000000..3412d773
--- /dev/null
+++ b/stovepipe/extension/storage/mysql/schema/BUILD.bazel
@@ -0,0 +1,5 @@
+filegroup(
+    name = "schema",
+    srcs = glob(["*.sql"]),
+    visibility = ["//visibility:public"],
+)
diff --git a/stovepipe/extension/storage/mysql/schema/request.sql b/stovepipe/extension/storage/mysql/schema/request.sql
new file mode 100644
index 00000000..207bdc5b
--- /dev/null
+++ b/stovepipe/extension/storage/mysql/schema/request.sql
@@ -0,0 +1,11 @@
+-- request holds one validation of a queue at a particular commit. uri is the opaque,
+-- VCS-agnostic commit locator; it may be empty until SourceControl resolution is wired in.
+-- No timestamps: created/updated times are not part of the Request entity.
+CREATE TABLE IF NOT EXISTS request (
+    id      VARCHAR(255) NOT NULL,
+    queue   VARCHAR(255) NOT NULL,
+    uri     VARCHAR(255) NOT NULL,
+    state   VARCHAR(64)  NOT NULL,
+    version INT          NOT NULL,
+    PRIMARY KEY (id)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
diff --git a/stovepipe/extension/storage/mysql/schema/request_uri.sql b/stovepipe/extension/storage/mysql/schema/request_uri.sql
new file mode 100644
index 00000000..853f2973
--- /dev/null
+++ b/stovepipe/extension/storage/mysql/schema/request_uri.sql
@@ -0,0 +1,13 @@
+-- request_uri is the reverse index from a validated commit to the request that owns it. The
+-- composite PK (queue, uri) enforces exactly one request per (queue, commit URI) — the RFC's
+-- dedup guarantee — and a duplicate insert surfaces as the "already being validated" signal.
+-- queue leads the PK so the row is addressed by its (queue, uri) key (NoSQL partition/sort style;
+-- no secondary indexes). version carries the optimistic-locking version for record consistency
+-- with the other stores; the mapping is currently insert-once, so it is written as 1.
+CREATE TABLE IF NOT EXISTS request_uri (
+    queue      VARCHAR(255) NOT NULL,
+    uri        VARCHAR(255) NOT NULL,
+    request_id VARCHAR(255) NOT NULL,
+    version    INT          NOT NULL,
+    PRIMARY KEY (queue, uri)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;
diff --git a/stovepipe/extension/storage/mysql/storage.go b/stovepipe/extension/storage/mysql/storage.go
new file mode 100644
index 00000000..93b04eb7
--- /dev/null
+++ b/stovepipe/extension/storage/mysql/storage.go
@@ -0,0 +1,54 @@
+// 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 mysql
+
+import (
+	"database/sql"
+
+	_ "github.com/go-sql-driver/mysql"
+	"github.com/uber-go/tally"
+
+	"github.com/uber/submitqueue/stovepipe/extension/storage"
+)
+
+type mysqlStorage struct {
+	db              *sql.DB
+	requestStore    storage.RequestStore
+	requestURIStore storage.RequestURIStore
+}
+
+// NewStorage creates a new MySQL-backed storage.
+func NewStorage(db *sql.DB, scope tally.Scope) (storage.Storage, error) {
+	return &mysqlStorage{
+		db:              db,
+		requestStore:    NewRequestStore(db, scope.SubScope("request_store")),
+		requestURIStore: NewRequestURIStore(db, scope.SubScope("request_uri_store")),
+	}, nil
+}
+
+// GetRequestStore returns the MySQL-backed RequestStore.
+func (f *mysqlStorage) GetRequestStore() storage.RequestStore {
+	return f.requestStore
+}
+
+// GetRequestURIStore returns the MySQL-backed RequestURIStore.
+func (f *mysqlStorage) GetRequestURIStore() storage.RequestURIStore {
+	return f.requestURIStore
+}
+
+// Close closes the underlying database connection.
+func (f *mysqlStorage) Close() error {
+	return f.db.Close()
+}
diff --git a/stovepipe/extension/storage/request_store.go b/stovepipe/extension/storage/request_store.go
new file mode 100644
index 00000000..4001bf0f
--- /dev/null
+++ b/stovepipe/extension/storage/request_store.go
@@ -0,0 +1,44 @@
+// 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 storage
+
+//go:generate mockgen -source=request_store.go -destination=mock/request_store_mock.go -package=mock
+
+import (
+	"context"
+
+	"github.com/uber/submitqueue/stovepipe/entity"
+)
+
+// RequestStore persists validation requests, keyed by request ID. The reverse index from a
+// validated commit to the request that owns it lives in a separate RequestURIStore (one store per
+// table), so the two concerns can evolve and be backed independently.
+type RequestStore interface {
+	// Create persists a new request. The request must have a unique ID already assigned.
+	// Returns ErrAlreadyExists if a request with the same ID already exists.
+	Create(ctx context.Context, request entity.Request) error
+
+	// Get retrieves a request by ID. Returns ErrNotFound if the request is not found.
+	Get(ctx context.Context, id string) (entity.Request, error)
+
+	// Update persists the mutable fields of request if the currently stored version matches
+	// oldVersion, writing newVersion as the new version. Returns ErrVersionMismatch if the
+	// stored version does not match (including when the request does not exist).
+	//
+	// Version arithmetic is owned by the caller: it computes newVersion (typically oldVersion+1)
+	// and only assigns request.Version = newVersion after this call succeeds. The store performs
+	// a pure conditional write and does not read request.Version.
+	Update(ctx context.Context, request entity.Request, oldVersion, newVersion int32) error
+}
diff --git a/stovepipe/extension/storage/request_uri_store.go b/stovepipe/extension/storage/request_uri_store.go
new file mode 100644
index 00000000..e5f9f6b7
--- /dev/null
+++ b/stovepipe/extension/storage/request_uri_store.go
@@ -0,0 +1,36 @@
+// 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 storage
+
+//go:generate mockgen -source=request_uri_store.go -destination=mock/request_uri_store_mock.go -package=mock
+
+import (
+	"context"
+)
+
+// RequestURIStore is the reverse index from a validated commit to the request that owns it,
+// keyed by (queue, commit URI). It is a separate store from RequestStore because it is a separate
+// table — the two are written independently (no cross-table transaction), keeping the contract
+// satisfiable by key/value backends. The caller orchestrates "create request, then map URI".
+type RequestURIStore interface {
+	// Create records that request id validates the commit uri for queue. Returns ErrAlreadyExists
+	// if (queue, uri) is already mapped — the signal a caller uses to detect that the commit is
+	// already being validated by another request.
+	Create(ctx context.Context, queue, uri, id string) error
+
+	// GetIDByURI returns the id of the request validating (queue, uri).
+	// Returns ErrNotFound if no request is mapped to that commit.
+	GetIDByURI(ctx context.Context, queue, uri string) (string, error)
+}
diff --git a/stovepipe/extension/storage/storage.go b/stovepipe/extension/storage/storage.go
new file mode 100644
index 00000000..d42406bb
--- /dev/null
+++ b/stovepipe/extension/storage/storage.go
@@ -0,0 +1,55 @@
+// 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 storage
+
+//go:generate mockgen -source=storage.go -destination=mock/storage_mock.go -package=mock
+
+import (
+	"errors"
+	"fmt"
+)
+
+// ErrNotFound is returned by storage implementations when the requested record is not found in the database.
+var ErrNotFound = errors.New("record not found")
+
+// IsNotFound returns true if any error in the error chain is a ErrNotFound.
+func IsNotFound(err error) bool {
+	return errors.Is(err, ErrNotFound)
+}
+
+// WrapNotFound wraps ErrNotFound with the original error from the storage implementation.
+func WrapNotFound(err error) error {
+	return fmt.Errorf("%w: %w", ErrNotFound, err)
+}
+
+// ErrAlreadyExists is returned by storage implementations when attempting to create a record that already exists.
+var ErrAlreadyExists = errors.New("record already exists")
+
+// ErrVersionMismatch is returned by storage implementations when a conditional (CAS) update finds that
+// the stored version does not match the expected version. It backs optimistic locking, letting callers
+// retry or converge instead of overwriting a concurrent change.
+var ErrVersionMismatch = errors.New("version mismatch")
+
+// Storage is a factory interface that aggregates all entity stores into a single injectable dependency.
+type Storage interface {
+	// GetRequestStore returns the RequestStore instance.
+	GetRequestStore() RequestStore
+
+	// GetRequestURIStore returns the RequestURIStore instance.
+	GetRequestURIStore() RequestURIStore
+
+	// Close closes the storage and all underlying connections. Should only be called once at the end of the program.
+	Close() error
+}
diff --git a/test/integration/stovepipe/extension/storage/mysql/BUILD.bazel b/test/integration/stovepipe/extension/storage/mysql/BUILD.bazel
new file mode 100644
index 00000000..2b3ec00c
--- /dev/null
+++ b/test/integration/stovepipe/extension/storage/mysql/BUILD.bazel
@@ -0,0 +1,24 @@
+load("@rules_go//go:def.bzl", "go_test")
+
+go_test(
+    name = "mysql_test",
+    srcs = ["storage_test.go"],
+    data = [
+        "docker-compose.yml",
+        "//stovepipe/extension/storage/mysql/schema",
+    ],
+    tags = [
+        "external",
+        "integration",
+    ],
+    deps = [
+        "//stovepipe/entity",
+        "//stovepipe/extension/storage",
+        "//stovepipe/extension/storage/mysql",
+        "//test/testutil",
+        "@com_github_go_sql_driver_mysql//:mysql",
+        "@com_github_stretchr_testify//require",
+        "@com_github_stretchr_testify//suite",
+        "@com_github_uber_go_tally//:tally",
+    ],
+)
diff --git a/test/integration/stovepipe/extension/storage/mysql/docker-compose.yml b/test/integration/stovepipe/extension/storage/mysql/docker-compose.yml
new file mode 100644
index 00000000..79d574b3
--- /dev/null
+++ b/test/integration/stovepipe/extension/storage/mysql/docker-compose.yml
@@ -0,0 +1,20 @@
+# Docker Compose for Stovepipe MySQL Storage tests.
+# Tests the storage extension's MySQL implementation in isolation.
+
+services:
+  mysql:
+    image: mysql:8.0
+    environment:
+      MYSQL_ROOT_PASSWORD: root
+      # Database name must match the shared testutil DSN (ConnectMySQLService).
+      MYSQL_DATABASE: submitqueue
+    ports:
+      - "3306" # Random ephemeral port to avoid conflicts
+    healthcheck:
+      # Use 127.0.0.1 (TCP) instead of localhost (Unix socket). MySQL treats
+      # "localhost" as a socket connection, which can be ready before the TCP
+      # listener — causing dependent services that connect over TCP to fail.
+      test: ["CMD", "mysqladmin", "ping", "-h", "127.0.0.1", "-proot"]
+      interval: 5s
+      timeout: 5s
+      retries: 10
diff --git a/test/integration/stovepipe/extension/storage/mysql/storage_test.go b/test/integration/stovepipe/extension/storage/mysql/storage_test.go
new file mode 100644
index 00000000..1efdf7f7
--- /dev/null
+++ b/test/integration/stovepipe/extension/storage/mysql/storage_test.go
@@ -0,0 +1,188 @@
+// 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 mysql
+
+import (
+	"context"
+	"database/sql"
+	"testing"
+
+	_ "github.com/go-sql-driver/mysql"
+	"github.com/stretchr/testify/require"
+	"github.com/stretchr/testify/suite"
+	"github.com/uber-go/tally"
+
+	"github.com/uber/submitqueue/stovepipe/entity"
+	"github.com/uber/submitqueue/stovepipe/extension/storage"
+	mysqlstorage "github.com/uber/submitqueue/stovepipe/extension/storage/mysql"
+	"github.com/uber/submitqueue/test/testutil"
+)
+
+// MySQLRequestStoreSuite exercises the MySQL-backed RequestStore against a real MySQL instance
+// started via docker-compose.
+type MySQLRequestStoreSuite struct {
+	suite.Suite
+	stack    *testutil.ComposeStack
+	db       *sql.DB
+	log      *testutil.TestLogger
+	ctx      context.Context
+	store    storage.RequestStore
+	uriStore storage.RequestURIStore
+}
+
+func TestMySQLRequestStore(t *testing.T) {
+	suite.Run(t, new(MySQLRequestStoreSuite))
+}
+
+func (s *MySQLRequestStoreSuite) SetupSuite() {
+	t := s.T()
+	s.ctx = context.Background()
+	s.log = testutil.NewTestLogger(t)
+
+	s.stack = testutil.NewComposeStack(
+		t,
+		s.log,
+		s.ctx,
+		"docker-compose.yml",
+		"ext-stovepipe-storage-mysql",
+	)
+
+	err := s.stack.Up()
+	require.NoError(t, err, "failed to start compose stack")
+
+	s.db, err = s.stack.ConnectMySQLService("mysql")
+	require.NoError(t, err, "failed to connect to MySQL")
+
+	schemaDir := testutil.SchemaDir("stovepipe/extension/storage/mysql/schema")
+	testutil.ApplySchema(t, s.log, s.db, schemaDir)
+
+	store, err := mysqlstorage.NewStorage(s.db, tally.NoopScope)
+	require.NoError(t, err, "failed to create storage")
+	s.store = store.GetRequestStore()
+	s.uriStore = store.GetRequestURIStore()
+
+	t.Cleanup(func() {
+		if s.db != nil {
+			s.db.Close()
+		}
+	})
+}
+
+func (s *MySQLRequestStoreSuite) TestCreateAndGet() {
+	req := entity.Request{
+		ID:      "request/monorepo/main/1",
+		Queue:   "monorepo/main",
+		URI:     "git://remote/monorepo/main/aaaa1111",
+		State:   entity.RequestStateAccepted,
+		Version: 1,
+	}
+	require.NoError(s.T(), s.store.Create(s.ctx, req))
+
+	got, err := s.store.Get(s.ctx, req.ID)
+	require.NoError(s.T(), err)
+	require.Equal(s.T(), req, got)
+}
+
+func (s *MySQLRequestStoreSuite) TestGetNotFound() {
+	_, err := s.store.Get(s.ctx, "request/monorepo/main/does-not-exist")
+	require.True(s.T(), storage.IsNotFound(err))
+}
+
+func (s *MySQLRequestStoreSuite) TestUpdateCAS() {
+	req := entity.Request{
+		ID:      "request/monorepo/main/update",
+		Queue:   "monorepo/main",
+		State:   entity.RequestStateAccepted,
+		Version: 1,
+	}
+	require.NoError(s.T(), s.store.Create(s.ctx, req))
+
+	// Successful CAS: stored version (1) matches oldVersion; resolve the URI and bump to 2.
+	updated := req
+	updated.URI = "git://remote/monorepo/main/resolved"
+	require.NoError(s.T(), s.store.Update(s.ctx, updated, 1, 2))
+
+	got, err := s.store.Get(s.ctx, req.ID)
+	require.NoError(s.T(), err)
+	require.Equal(s.T(), "git://remote/monorepo/main/resolved", got.URI)
+	require.Equal(s.T(), int32(2), got.Version)
+
+	// Stale CAS: oldVersion 1 no longer matches the stored version (2).
+	err = s.store.Update(s.ctx, updated, 1, 2)
+	require.ErrorIs(s.T(), err, storage.ErrVersionMismatch)
+}
+
+func (s *MySQLRequestStoreSuite) TestUpdateNotFoundIsVersionMismatch() {
+	missing := entity.Request{ID: "request/monorepo/main/missing", State: entity.RequestStateAccepted}
+	err := s.store.Update(s.ctx, missing, 1, 2)
+	require.ErrorIs(s.T(), err, storage.ErrVersionMismatch)
+}
+
+func (s *MySQLRequestStoreSuite) TestCreateDuplicateID() {
+	req := entity.Request{
+		ID:      "request/monorepo/main/2",
+		Queue:   "monorepo/main",
+		State:   entity.RequestStateAccepted,
+		Version: 1,
+	}
+	require.NoError(s.T(), s.store.Create(s.ctx, req))
+
+	err := s.store.Create(s.ctx, req)
+	require.ErrorIs(s.T(), err, storage.ErrAlreadyExists)
+}
+
+func (s *MySQLRequestStoreSuite) TestURIMappingCreateAndGet() {
+	const (
+		queue = "monorepo/main"
+		uri   = "git://remote/monorepo/main/bbbb2222"
+		id    = "request/monorepo/main/3"
+	)
+	require.NoError(s.T(), s.uriStore.Create(s.ctx, queue, uri, id))
+
+	got, err := s.uriStore.GetIDByURI(s.ctx, queue, uri)
+	require.NoError(s.T(), err)
+	require.Equal(s.T(), id, got)
+}
+
+func (s *MySQLRequestStoreSuite) TestGetIDByURINotFound() {
+	_, err := s.uriStore.GetIDByURI(s.ctx, "monorepo/main", "git://remote/monorepo/main/unmapped")
+	require.True(s.T(), storage.IsNotFound(err))
+}
+
+func (s *MySQLRequestStoreSuite) TestURIMappingDuplicate() {
+	const (
+		queue = "monorepo/main"
+		uri   = "git://remote/monorepo/main/cccc3333"
+	)
+	require.NoError(s.T(), s.uriStore.Create(s.ctx, queue, uri, "request/monorepo/main/4"))
+
+	// A second request claiming the same (queue, uri) is rejected — the dedup signal.
+	err := s.uriStore.Create(s.ctx, queue, uri, "request/monorepo/main/5")
+	require.ErrorIs(s.T(), err, storage.ErrAlreadyExists)
+}
+
+func (s *MySQLRequestStoreSuite) TestURIMappingDistinctAcrossQueues() {
+	const uri = "git://remote/monorepo/shared/dddd4444"
+	require.NoError(s.T(), s.uriStore.Create(s.ctx, "queue-a", uri, "request/queue-a/1"))
+	require.NoError(s.T(), s.uriStore.Create(s.ctx, "queue-b", uri, "request/queue-b/1"))
+
+	idA, err := s.uriStore.GetIDByURI(s.ctx, "queue-a", uri)
+	require.NoError(s.T(), err)
+	require.Equal(s.T(), "request/queue-a/1", idA)
+
+	idB, err := s.uriStore.GetIDByURI(s.ctx, "queue-b", uri)
+	require.NoError(s.T(), err)
+	require.Equal(s.T(), "request/queue-b/1", idB)
+}