diff --git a/cloudflare/src/devices.ts b/cloudflare/src/devices.ts
index 3e05cd5..9134d22 100644
--- a/cloudflare/src/devices.ts
+++ b/cloudflare/src/devices.ts
@@ -54,6 +54,65 @@ const DEVICE_BY_IDEMPOTENCY_KEY_QUERY = `
   FROM user_devices
   WHERE user_id = ? AND idempotency_key = ?
 `;
+const DEVICE_BY_ID_QUERY = `
+  SELECT
+    device_id,
+    public_key,
+    device_name,
+    platform,
+    approval_status,
+    created_at,
+    approved_at,
+    last_active_at,
+    revoked_at
+  FROM user_devices
+  WHERE user_id = ? AND device_id = ?
+`;
+const APPROVED_DEVICE_QUERY = `
+  SELECT
+    device_id,
+    public_key,
+    device_name,
+    platform,
+    approval_status,
+    created_at,
+    approved_at,
+    last_active_at,
+    revoked_at
+  FROM user_devices
+  WHERE user_id = ? AND device_id = ? AND approval_status = 'approved' AND revoked_at IS NULL
+`;
+const DEVICE_APPROVAL_BY_IDEMPOTENCY_KEY_QUERY = `
+  SELECT
+    device_id,
+    requester_device_id,
+    status,
+    decided_at
+  FROM device_approvals
+  WHERE user_id = ? AND idempotency_key = ?
+`;
+const DEVICE_APPROVAL_INSERT_QUERY = `
+  INSERT INTO device_approvals (
+    user_id,
+    approval_id,
+    device_id,
+    requester_device_id,
+    status,
+    requested_at,
+    decided_at,
+    expires_at,
+    idempotency_key
+  ) VALUES (?, ?, ?, ?, 'approved', ?, ?, ?, ?)
+  ON CONFLICT(user_id, idempotency_key) DO NOTHING
+`;
+const DEVICE_APPROVE_QUERY = `
+  UPDATE user_devices
+  SET
+    approval_status = 'approved',
+    approved_at = COALESCE(approved_at, ?),
+    last_active_at = ?
+  WHERE user_id = ? AND device_id = ? AND approval_status = 'pending' AND revoked_at IS NULL
+`;
 
 export interface DeviceListDocument {
   version: 1;
@@ -67,6 +126,14 @@ export interface DeviceRegistrationDocument {
   device: DeviceDocument;
 }
 
+export interface DeviceApprovalDocument {
+  version: 1;
+  user_id: string;
+  approved_by_device_id: string;
+  approved_at: number;
+  device: DeviceDocument;
+}
+
 export interface DeviceDocument {
   device_id: string;
   public_key: string;
@@ -100,7 +167,16 @@ interface DeviceRegistrationRequest {
   idempotencyKey: string;
 }
 
-type DeviceRegistrationBody = Record<string, unknown>;
+type DeviceApprovalRequest = { deviceId: string; idempotencyKey: string };
+
+interface DeviceApprovalRow {
+  device_id: unknown;
+  requester_device_id: unknown;
+  status: unknown;
+  decided_at: unknown;
+}
+
+type DeviceRequestBody = Record<string, unknown>;
 
 export class DeviceSchemaError extends Error {
   constructor(message: string) {
@@ -172,16 +248,69 @@ export async function registerDeviceDocument(
   };
 }
 
+export async function approveDeviceDocument(
+  request: Request,
+  env: Env,
+  context: AuthContext,
+  nowSeconds = Math.floor(Date.now() / 1000),
+): Promise<DeviceApprovalDocument> {
+  const approval = await deviceApprovalRequest(request);
+  const requesterDeviceId = currentDeviceId(context);
+  if (requesterDeviceId === approval.deviceId) {
+    throw new DevicePermissionError("device_self_approval_forbidden");
+  }
+
+  const existingApproval = await env.ELY_DB.prepare(DEVICE_APPROVAL_BY_IDEMPOTENCY_KEY_QUERY)
+    .bind(context.userId, approval.idempotencyKey)
+    .first<DeviceApprovalRow>();
+  if (existingApproval !== null) {
+    return existingApprovalDocument(env, context, approval, requesterDeviceId, existingApproval);
+  }
+
+  const approver = await env.ELY_DB.prepare(APPROVED_DEVICE_QUERY)
+    .bind(context.userId, requesterDeviceId)
+    .first<DeviceRow>();
+  if (approver === null) {
+    throw new DevicePermissionError("approver_device_unapproved");
+  }
+
+  const pendingDevice = await deviceRowById(env, context.userId, approval.deviceId);
+  if (pendingDevice === null) {
+    throw new DevicePermissionError("device_not_found");
+  }
+  const pendingDocument = deviceDocument(pendingDevice, requesterDeviceId);
+  if (pendingDocument.approval_status !== "pending" || pendingDocument.revoked_at !== null) {
+    throw new DevicePermissionError("device_not_pending");
+  }
+
+  await env.ELY_DB.batch([
+    env.ELY_DB.prepare(DEVICE_APPROVAL_INSERT_QUERY).bind(
+      context.userId,
+      approval.idempotencyKey,
+      approval.deviceId,
+      requesterDeviceId,
+      nowSeconds,
+      nowSeconds,
+      nowSeconds,
+      approval.idempotencyKey,
+    ),
+    env.ELY_DB.prepare(DEVICE_APPROVE_QUERY).bind(
+      nowSeconds,
+      nowSeconds,
+      context.userId,
+      approval.deviceId,
+    ),
+  ]);
+
+  const approvedDevice = await deviceRowById(env, context.userId, approval.deviceId);
+  if (approvedDevice === null) {
+    throw new DevicePersistenceError("device_approval_missing");
+  }
+  return approvedDeviceDocument(context.userId, requesterDeviceId, approvedDevice);
+}
+
 async function deviceRegistrationRequest(request: Request): Promise<DeviceRegistrationRequest> {
-  let value: unknown;
-  try {
-    value = await request.json();
-  } catch {
-    throw new DeviceSchemaError("device_registration_json_invalid");
-  }
-  if (!isRecord(value)) {
-    throw new DeviceSchemaError("device_registration_must_be_object");
-  }
+  const value = await deviceRequestBody(request, "device_registration");
   assertOnlyFields(value, [
     "version",
     "device_id",
@@ -203,6 +332,89 @@ async function deviceRegistrationRequest(request: Request): Promise<DeviceRegist
   };
 }
 
+async function deviceApprovalRequest(request: Request): Promise<DeviceApprovalRequest> {
+  const value = await deviceRequestBody(request, "device_approval");
+  assertOnlyFields(value, ["version", "device_id", "idempotency_key"]);
+  if (value.version !== 1) {
+    throw new DeviceSchemaError("device_approval_version_invalid");
+  }
+
+  return {
+    deviceId: deviceIdValue(value.device_id, "device_id"),
+    idempotencyKey: idempotencyKeyValue(value.idempotency_key),
+  };
+}
+
+async function existingApprovalDocument(
+  env: Env,
+  context: AuthContext,
+  approval: DeviceApprovalRequest,
+  requesterDeviceId: string,
+  row: DeviceApprovalRow,
+): Promise<DeviceApprovalDocument> {
+  const approvedDeviceId = deviceIdValue(row.device_id, "device_id");
+  const approvedByDeviceId = deviceIdValue(row.requester_device_id, "requester_device_id");
+  if (
+    approvedDeviceId !== approval.deviceId ||
+    approvedByDeviceId !== requesterDeviceId ||
+    row.status !== "approved"
+  ) {
+    throw new DevicePermissionError("device_approval_replay_mismatch");
+  }
+
+  const approvedDevice = await deviceRowById(env, context.userId, approvedDeviceId);
+  if (approvedDevice === null) {
+    throw new DevicePersistenceError("device_approval_missing");
+  }
+
+  return {
+    ...approvedDeviceDocument(context.userId, requesterDeviceId, approvedDevice),
+    approved_at: timestamp(row.decided_at, "decided_at"),
+  };
+}
+
+function approvedDeviceDocument(
+  userId: string,
+  approvedByDeviceId: string,
+  row: DeviceRow,
+): DeviceApprovalDocument {
+  const device = deviceDocument(row, approvedByDeviceId);
+  if (device.approval_status !== "approved" || device.approved_at === null) {
+    throw new DevicePersistenceError("device_approval_missing");
+  }
+  return {
+    version: 1,
+    user_id: userId,
+    approved_by_device_id: approvedByDeviceId,
+    approved_at: device.approved_at,
+    device,
+  };
+}
+
+function currentDeviceId(context: AuthContext): string {
+  if (context.deviceId === undefined) {
+    throw new DevicePermissionError("device_context_required");
+  }
+  return context.deviceId;
+}
+
+async function deviceRowById(env: Env, userId: string, deviceId: string): Promise<DeviceRow | null> {
+  return env.ELY_DB.prepare(DEVICE_BY_ID_QUERY).bind(userId, deviceId).first<DeviceRow>();
+}
+
+async function deviceRequestBody(request: Request, label: string): Promise<DeviceRequestBody> {
+  let value: unknown;
+  try {
+    value = await request.json();
+  } catch {
+    throw new DeviceSchemaError(`${label}_json_invalid`);
+  }
+  if (!isRecord(value)) {
+    throw new DeviceSchemaError(`${label}_must_be_object`);
+  }
+  return value;
+}
+
 function deviceDocument(row: DeviceRow, currentDeviceId: string | undefined): DeviceDocument {
   const deviceId = deviceIdValue(row.device_id, "device_id");
   return {
@@ -272,7 +484,7 @@ function timestamp(value: unknown, label: string): number {
   return value;
 }
 
-function assertOnlyFields(value: DeviceRegistrationBody, fields: string[]): void {
+function assertOnlyFields(value: DeviceRequestBody, fields: string[]): void {
   const allowed = new Set(fields);
   for (const field of Object.keys(value)) {
     if (!allowed.has(field)) {
@@ -281,6 +493,6 @@ function assertOnlyFields(value: DeviceRegistrationBody, fields: string[]): void
   }
 }
 
-function isRecord(value: unknown): value is DeviceRegistrationBody {
+function isRecord(value: unknown): value is DeviceRequestBody {
   return typeof value === "object" && value !== null && !Array.isArray(value);
 }
diff --git a/cloudflare/src/index.ts b/cloudflare/src/index.ts
index 70526d5..124680a 100644
--- a/cloudflare/src/index.ts
+++ b/cloudflare/src/index.ts
@@ -4,6 +4,7 @@ import {
   DevicePermissionError,
   DevicePersistenceError,
   DeviceSchemaError,
+  approveDeviceDocument,
   deviceListDocument,
   registerDeviceDocument,
 } from "./devices.js";
@@ -91,6 +92,44 @@ export async function handleRequest(request: Request, env: Env): Promise<Respons
       },
     );
   }
+  if (url.pathname === "/api/devices/approve") {
+    return withAuthenticatedApiControls(
+      request,
+      env,
+      "devices.approve",
+      ["POST"],
+      async (context) => {
+        try {
+          return jsonResponse(await approveDeviceDocument(request, env, context), 200, {
+            "Cache-Control": "no-store",
+          });
+        } catch (error) {
+          if (error instanceof DevicePermissionError) {
+            return jsonResponse(
+              { error: "device_approval_forbidden" },
+              403,
+              { "Cache-Control": "no-store" },
+            );
+          }
+          if (error instanceof DeviceSchemaError) {
+            return jsonResponse(
+              { error: "invalid_device_approval" },
+              400,
+              { "Cache-Control": "no-store" },
+            );
+          }
+          if (error instanceof DevicePersistenceError) {
+            return jsonResponse(
+              { error: "device_approval_failed" },
+              500,
+              { "Cache-Control": "no-store" },
+            );
+          }
+          throw error;
+        }
+      },
+    );
+  }
   if (url.pathname === "/api/plugins/signing-keys") {
     return withPublicApiControls(request, env, "plugins.signing_keys", ["GET"], () =>
       handlePublicSigningKeys(env),
diff --git a/cloudflare/tests/devices_approval_routes.test.ts b/cloudflare/tests/devices_approval_routes.test.ts
new file mode 100644
index 0000000..c55813d
--- /dev/null
+++ b/cloudflare/tests/devices_approval_routes.test.ts
@@ -0,0 +1,235 @@
+import assert from "node:assert/strict";
+import { describe, it } from "node:test";
+
+import { authSessionCacheKvKey, authTokenHash } from "../src/auth.js";
+import { handleRequest } from "../src/index.js";
+import {
+  ACCESS_TOKEN,
+  PUBLIC_KEY,
+  sessionDocument,
+  testD1Database,
+  testEnv,
+} from "./devices_test_support.js";
+
+const DEVICE_APPROVAL_IDEMPOTENCY_KEY = "device-approval-0001";
+
+describe("device approval routes", () => {
+  it("approves a pending device from an approved current device", async () => {
+    const tokenHash = await authTokenHash(ACCESS_TOKEN);
+    const d1 = testD1Database({
+      firstRows: [
+        null,
+        deviceRow({ device_id: "device-01", approval_status: "approved" }),
+        deviceRow({ device_id: "device-02", approval_status: "pending", approved_at: null }),
+        deviceRow({
+          device_id: "device-02",
+          approval_status: "approved",
+          approved_at: 1_780_000_300,
+        }),
+      ],
+    });
+
+    const response = await handleRequest(
+      new Request("https://elydora.test/api/devices/approve", {
+        method: "POST",
+        headers: {
+          authorization: `Bearer ${ACCESS_TOKEN}`,
+          "content-type": "application/json",
+        },
+        body: JSON.stringify(deviceApprovalBody()),
+      }),
+      testEnv({
+        d1,
+        kvEntries: [[authSessionCacheKvKey("local", tokenHash), sessionDocument("device-01")]],
+      }),
+    );
+
+    assert.equal(response.status, 200);
+    assert.equal(response.headers.get("cache-control"), "no-store");
+    assert.deepEqual(await response.json(), {
+      version: 1,
+      user_id: "user-01",
+      approved_by_device_id: "device-01",
+      approved_at: 1_780_000_300,
+      device: {
+        device_id: "device-02",
+        public_key: PUBLIC_KEY,
+        device_name: "MacBook Pro",
+        platform: "macOS",
+        approval_status: "approved",
+        created_at: 1_780_000_000,
+        approved_at: 1_780_000_300,
+        last_active_at: 1_780_000_020,
+        revoked_at: null,
+        current: false,
+      },
+    });
+    assert.equal(d1.batches[0], 2);
+    assert.ok(d1.queries[0]?.includes("FROM device_approvals"));
+    assert.ok(d1.queries[1]?.includes("approval_status = 'approved'"));
+    assert.ok(d1.queries[3]?.includes("INSERT INTO device_approvals"));
+    assert.ok(d1.queries[4]?.includes("UPDATE user_devices"));
+    assert.deepEqual(d1.binds[0], ["user-01", DEVICE_APPROVAL_IDEMPOTENCY_KEY]);
+    assert.deepEqual(d1.binds[1], ["user-01", "device-01"]);
+    assert.deepEqual(d1.binds[2], ["user-01", "device-02"]);
+    assert.deepEqual(d1.binds[3]?.slice(0, 4), [
+      "user-01",
+      DEVICE_APPROVAL_IDEMPOTENCY_KEY,
+      "device-02",
+      "device-01",
+    ]);
+    assert.equal(d1.binds[3]?.[7], DEVICE_APPROVAL_IDEMPOTENCY_KEY);
+    assert.deepEqual(d1.binds[5], ["user-01", "device-02"]);
+  });
+
+  it("returns the existing approval for an idempotent replay", async () => {
+    const tokenHash = await authTokenHash(ACCESS_TOKEN);
+    const d1 = testD1Database({
+      firstRows: [
+        {
+          device_id: "device-02",
+          requester_device_id: "device-01",
+          status: "approved",
+          decided_at: 1_780_000_300,
+        },
+        deviceRow({
+          device_id: "device-02",
+          approval_status: "approved",
+          approved_at: 1_780_000_300,
+        }),
+      ],
+    });
+
+    const response = await handleRequest(
+      new Request("https://elydora.test/api/devices/approve", {
+        method: "POST",
+        headers: {
+          authorization: `Bearer ${ACCESS_TOKEN}`,
+          "content-type": "application/json",
+        },
+        body: JSON.stringify(deviceApprovalBody()),
+      }),
+      testEnv({
+        d1,
+        kvEntries: [[authSessionCacheKvKey("local", tokenHash), sessionDocument("device-01")]],
+      }),
+    );
+
+    assert.equal(response.status, 200);
+    const body = (await response.json()) as { approved_at: number };
+    assert.equal(body.approved_at, 1_780_000_300);
+    assert.deepEqual(d1.batches, []);
+    assert.equal(d1.queries.length, 2);
+    assert.deepEqual(d1.binds, [
+      ["user-01", DEVICE_APPROVAL_IDEMPOTENCY_KEY],
+      ["user-01", "device-02"],
+    ]);
+  });
+
+  it("rejects approval from a current device that is not approved", async () => {
+    const tokenHash = await authTokenHash(ACCESS_TOKEN);
+    const d1 = testD1Database({ firstRows: [null, null] });
+    const response = await handleRequest(
+      new Request("https://elydora.test/api/devices/approve", {
+        method: "POST",
+        headers: {
+          authorization: `Bearer ${ACCESS_TOKEN}`,
+          "content-type": "application/json",
+        },
+        body: JSON.stringify(deviceApprovalBody()),
+      }),
+      testEnv({
+        d1,
+        kvEntries: [[authSessionCacheKvKey("local", tokenHash), sessionDocument("device-01")]],
+      }),
+    );
+
+    assert.equal(response.status, 403);
+    assert.deepEqual(await response.json(), { error: "device_approval_forbidden" });
+    assert.deepEqual(d1.batches, []);
+  });
+
+  it("rejects self approval before D1 writes", async () => {
+    const tokenHash = await authTokenHash(ACCESS_TOKEN);
+    const d1 = testD1Database([]);
+    const response = await handleRequest(
+      new Request("https://elydora.test/api/devices/approve", {
+        method: "POST",
+        headers: {
+          authorization: `Bearer ${ACCESS_TOKEN}`,
+          "content-type": "application/json",
+        },
+        body: JSON.stringify({ ...deviceApprovalBody(), device_id: "device-01" }),
+      }),
+      testEnv({
+        d1,
+        kvEntries: [[authSessionCacheKvKey("local", tokenHash), sessionDocument("device-01")]],
+      }),
+    );
+
+    assert.equal(response.status, 403);
+    assert.deepEqual(d1.queries, []);
+  });
+
+  it("rejects invalid approval payloads before D1 writes", async () => {
+    const tokenHash = await authTokenHash(ACCESS_TOKEN);
+    const d1 = testD1Database([]);
+    const response = await handleRequest(
+      new Request("https://elydora.test/api/devices/approve", {
+        method: "POST",
+        headers: {
+          authorization: `Bearer ${ACCESS_TOKEN}`,
+          "content-type": "application/json",
+        },
+        body: JSON.stringify({ ...deviceApprovalBody(), idempotency_key: "short" }),
+      }),
+      testEnv({
+        d1,
+        kvEntries: [[authSessionCacheKvKey("local", tokenHash), sessionDocument("device-01")]],
+      }),
+    );
+
+    assert.equal(response.status, 400);
+    assert.deepEqual(await response.json(), { error: "invalid_device_approval" });
+    assert.deepEqual(d1.queries, []);
+  });
+
+  it("rejects unauthenticated device approval before D1 writes", async () => {
+    const d1 = testD1Database([]);
+    const response = await handleRequest(
+      new Request("https://elydora.test/api/devices/approve", {
+        method: "POST",
+        headers: { "content-type": "application/json" },
+        body: JSON.stringify(deviceApprovalBody()),
+      }),
+      testEnv({ d1 }),
+    );
+
+    assert.equal(response.status, 401);
+    assert.deepEqual(await response.json(), { error: "authorization_missing" });
+    assert.deepEqual(d1.queries, []);
+  });
+});
+
+function deviceApprovalBody(): Record<string, unknown> {
+  return {
+    version: 1,
+    device_id: "device-02",
+    idempotency_key: DEVICE_APPROVAL_IDEMPOTENCY_KEY,
+  };
+}
+
+function deviceRow(overrides: Record<string, unknown>): Record<string, unknown> {
+  return {
+    device_id: "device-01",
+    public_key: PUBLIC_KEY,
+    device_name: "MacBook Pro",
+    platform: "macOS",
+    approval_status: "approved",
+    created_at: 1_780_000_000,
+    approved_at: 1_780_000_010,
+    last_active_at: 1_780_000_020,
+    revoked_at: null,
+    ...overrides,
+  };
+}
diff --git a/cloudflare/tests/devices_routes.test.ts b/cloudflare/tests/devices_routes.test.ts
index e999dae..1d4a639 100644
--- a/cloudflare/tests/devices_routes.test.ts
+++ b/cloudflare/tests/devices_routes.test.ts
@@ -1,18 +1,17 @@
 import assert from "node:assert/strict";
 import { describe, it } from "node:test";
 
-import type {
-  ElyAnalyticsDataPoint,
-  ElyD1Database,
-  ElyD1PreparedStatement,
-  ElyR2PutOptions,
-  Env,
-} from "../src/bindings.js";
+import type { ElyAnalyticsDataPoint } from "../src/bindings.js";
 import { authSessionCacheKvKey, authTokenHash } from "../src/auth.js";
 import { handleRequest } from "../src/index.js";
+import {
+  ACCESS_TOKEN,
+  PUBLIC_KEY,
+  sessionDocument,
+  testD1Database,
+  testEnv,
+} from "./devices_test_support.js";
 
-const ACCESS_TOKEN = "D".repeat(48);
-const PUBLIC_KEY = "a".repeat(64);
 const IDEMPOTENCY_KEY = "device-register-0001";
 
 describe("device routes", () => {
@@ -284,82 +283,6 @@ describe("device routes", () => {
   });
 });
 
-interface TestEnvOptions {
-  auditEvents?: ElyAnalyticsDataPoint[];
-  d1?: RecordedD1Database;
-  kvEntries?: [string, string][];
-  kvReads?: string[];
-}
-
-interface RecordedD1Database extends ElyD1Database {
-  binds: unknown[][];
-  queries: string[];
-}
-
-function testEnv(options: TestEnvOptions): Env {
-  const values = new Map(options.kvEntries ?? []);
-  return {
-    ELY_ENVIRONMENT: "local",
-    ELY_DB: options.d1 ?? testD1Database([]),
-    ELY_KV: {
-      get(key: string): Promise<string | null> {
-        options.kvReads?.push(key);
-        return Promise.resolve(values.get(key) ?? null);
-      },
-    },
-    ELY_STORAGE: testR2Bucket(),
-    ELY_RATE_LIMITER: {
-      limit(): Promise<{ success: boolean }> {
-        return Promise.resolve({ success: true });
-      },
-    },
-    ELY_API_AUDIT: {
-      writeDataPoint(event?: ElyAnalyticsDataPoint): void {
-        if (event !== undefined) {
-          options.auditEvents?.push(event);
-        }
-      },
-    },
-  };
-}
-
-function testD1Database(rows: unknown[]): RecordedD1Database {
-  const binds: unknown[][] = [];
-  const queries: string[] = [];
-  return {
-    binds,
-    queries,
-    prepare(query: string) {
-      queries.push(query);
-      return testD1PreparedStatement(rows, binds);
-    },
-    batch() {
-      return Promise.resolve([]);
-    },
-    exec() {
-      return Promise.resolve({});
-    },
-  };
-}
-
-function testD1PreparedStatement(rows: unknown[], binds: unknown[][]): ElyD1PreparedStatement {
-  return {
-    bind(...values: unknown[]) {
-      binds.push(values);
-      return this;
-    },
-    first<T>() {
-      return Promise.resolve((rows[0] as T | undefined) ?? null);
-    },
-    all<T>() {
-      return Promise.resolve({ results: rows as T[] });
-    },
-    run() {
-      return Promise.resolve({});
-    },
-  };
-}
-
 function deviceRegistrationBody(): Record<string, unknown> {
   return {
     version: 1,
@@ -370,28 +293,3 @@ function deviceRegistrationBody(): Record<string, unknown> {
     idempotency_key: IDEMPOTENCY_KEY,
   };
 }
-
-function testR2Bucket(): Env["ELY_STORAGE"] {
-  return {
-    get() {
-      return Promise.resolve(null);
-    },
-    put(_key: string, value: ArrayBuffer, _options?: ElyR2PutOptions) {
-      return Promise.resolve({
-        arrayBuffer() {
-          return Promise.resolve(value);
-        },
-      });
-    },
-  };
-}
-
-function sessionDocument(): string {
-  return JSON.stringify({
-    version: 1,
-    user_id: "user-01",
-    session_id: "session-01",
-    device_id: "device-01",
-    expires_at: "2099-01-01T00:00:00.000Z",
-  });
-}
diff --git a/cloudflare/tests/devices_test_support.ts b/cloudflare/tests/devices_test_support.ts
new file mode 100644
index 0000000..6822f45
--- /dev/null
+++ b/cloudflare/tests/devices_test_support.ts
@@ -0,0 +1,128 @@
+import type {
+  ElyAnalyticsDataPoint,
+  ElyD1Database,
+  ElyD1PreparedStatement,
+  ElyR2PutOptions,
+  Env,
+} from "../src/bindings.js";
+
+export const ACCESS_TOKEN = "D".repeat(48);
+export const PUBLIC_KEY = "a".repeat(64);
+
+export interface TestEnvOptions {
+  auditEvents?: ElyAnalyticsDataPoint[];
+  d1?: RecordedD1Database;
+  kvEntries?: [string, string][];
+  kvReads?: string[];
+}
+
+export interface RecordedD1Database extends ElyD1Database {
+  batches: number[];
+  binds: unknown[][];
+  queries: string[];
+}
+
+interface TestD1DatabaseOptions {
+  allRows?: unknown[];
+  firstRows?: unknown[];
+}
+
+export function testEnv(options: TestEnvOptions): Env {
+  const values = new Map(options.kvEntries ?? []);
+  return {
+    ELY_ENVIRONMENT: "local",
+    ELY_DB: options.d1 ?? testD1Database([]),
+    ELY_KV: {
+      get(key: string): Promise<string | null> {
+        options.kvReads?.push(key);
+        return Promise.resolve(values.get(key) ?? null);
+      },
+    },
+    ELY_STORAGE: testR2Bucket(),
+    ELY_RATE_LIMITER: {
+      limit(): Promise<{ success: boolean }> {
+        return Promise.resolve({ success: true });
+      },
+    },
+    ELY_API_AUDIT: {
+      writeDataPoint(event?: ElyAnalyticsDataPoint): void {
+        if (event !== undefined) {
+          options.auditEvents?.push(event);
+        }
+      },
+    },
+  };
+}
+
+export function testD1Database(rows: unknown[] | TestD1DatabaseOptions): RecordedD1Database {
+  const binds: unknown[][] = [];
+  const batches: number[] = [];
+  const queries: string[] = [];
+  const allRows = Array.isArray(rows) ? rows : rows.allRows ?? [];
+  const firstRows = Array.isArray(rows) ? rows : rows.firstRows ?? [];
+  let firstIndex = 0;
+  return {
+    batches,
+    binds,
+    queries,
+    prepare(query: string) {
+      queries.push(query);
+      return testD1PreparedStatement(allRows, firstRows, () => firstIndex++, binds);
+    },
+    batch(statements: ElyD1PreparedStatement[]) {
+      batches.push(statements.length);
+      return Promise.resolve([]);
+    },
+    exec() {
+      return Promise.resolve({});
+    },
+  };
+}
+
+export function sessionDocument(deviceId = "device-01"): string {
+  return JSON.stringify({
+    version: 1,
+    user_id: "user-01",
+    session_id: "session-01",
+    device_id: deviceId,
+    expires_at: "2099-01-01T00:00:00.000Z",
+  });
+}
+
+function testD1PreparedStatement(
+  allRows: unknown[],
+  firstRows: unknown[],
+  nextFirstIndex: () => number,
+  binds: unknown[][],
+): ElyD1PreparedStatement {
+  return {
+    bind(...values: unknown[]) {
+      binds.push(values);
+      return this;
+    },
+    first<T>() {
+      return Promise.resolve((firstRows[nextFirstIndex()] as T | undefined) ?? null);
+    },
+    all<T>() {
+      return Promise.resolve({ results: allRows as T[] });
+    },
+    run() {
+      return Promise.resolve({});
+    },
+  };
+}
+
+function testR2Bucket(): Env["ELY_STORAGE"] {
+  return {
+    get() {
+      return Promise.resolve(null);
+    },
+    put(_key: string, value: ArrayBuffer, _options?: ElyR2PutOptions) {
+      return Promise.resolve({
+        arrayBuffer() {
+          return Promise.resolve(value);
+        },
+      });
+    },
+  };
+}