build: dual CJS/ESM output, ES2020 target, Node 18 floor

"exports" gains "import" and "types" next to "require": import "alex2node" failed with
ERR_PACKAGE_PATH_NOT_EXPORTED. scripts/build.mjs compiles src/ to dist/cjs, dist/esm and dist/types in a staging
directory and swaps them in only when both compiler runs passed. "main" and "types" follow for resolvers that do
not read "exports". Target ES6 -> ES2020, "engines": node >= 18, relative imports carry ".js" for Node's ESM loader.
uuid gives way to crypto.randomUUID(); mqtt is the only runtime dependency left.

Tests load the package by name. New: both entry points, the modules the builds import, dist/ equal to a fresh
build, a round trip on the ES module build, and two compiled type fixtures in place of the .d.ts regexes.
22 tests pass in 5.7 s. dist/: 16 files, 79,711 B -> 25 files, 132,291 B; the npm tarball is 25,125 B.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/Alex2Node.ts

@@ -1,8 +1,10 @@
-import mqtt, { MqttClient, IClientOptions } from "mqtt";
-import Device from "./Device";
+// mqtt reaches Node as CommonJS: the default import works from both builds, a named one needs Node to detect it.
+import mqtt from "mqtt";
+import type { MqttClient, IClientOptions } from "mqtt";
+import Device from "./Device.js";
 import { EventEmitter } from "events";
-import { DisplayCategory } from "./DisplayCategory";
-import { AlexaInterfaceType } from "./AlexaInterface";
+import { DisplayCategory } from "./DisplayCategory.js";
+import { AlexaInterfaceType } from "./AlexaInterface.js";
 
 /** Optional settings for the bridge (1.5.1). Everything has the 1.4.0 behaviour as its default. */
 export interface Alex2MQTTOptions {

src/AlexaErrorResponse.ts

@@ -1,6 +1,5 @@
-import { v4 as uuidv4 } from "uuid";
-import { AlexaInterface, AlexaInterfaceType } from "./AlexaInterface";
-import { MqttClient } from "mqtt";
+import { randomUUID } from "crypto";
+import type { MqttClient } from "mqtt";
 
 export enum AlexaErrorType {
   ALREADY_IN_OPERATION = "ALREADY_IN_OPERATION",
@@ -102,7 +101,7 @@ export class AlexaErrorResponse {
       header: {
         namespace: "Alexa",
         name: "ErrorResponse",
-        messageId: this.generateMessageId(),
+        messageId: randomUUID(),
         correlationToken,
         payloadVersion: "3",
       },
@@ -112,9 +111,6 @@ export class AlexaErrorResponse {
       payload: {},
     };
   }
-  private generateMessageId(): string {
-    return uuidv4();
-  }
   setErrorMessage(
     type: string,
     message: string,

src/AlexaInterface.ts

@@ -1,4 +1,4 @@
-import { ActionMapping, AlexaActions } from "./ActionMapping";
+import type { ActionMapping } from "./ActionMapping.js";
 
 export enum AlexaInterfaceType {
   APPLICATION_STATE_REPORTER = "Alexa.ApplicationStateReporter",

src/AlexaStatusMessage.ts

@@ -1,6 +1,6 @@
-import { v4 as uuidv4 } from "uuid";
-import { AlexaInterface, AlexaInterfaceType } from "./AlexaInterface";
-import { MqttClient } from "mqtt";
+import { randomUUID } from "crypto";
+import { AlexaInterfaceType } from "./AlexaInterface.js";
+import type { MqttClient } from "mqtt";
 
 export enum EndpointHealth {
   OK = "OK",
@@ -94,7 +94,7 @@ export class AlexaStatusMessage {
           ? "Response"
           : "StateReport",
         payloadVersion: "3",
-        messageId: this.generateMessageId(),
+        messageId: randomUUID(),
         correlationToken,
       },
       endpoint: {
@@ -104,10 +104,6 @@ export class AlexaStatusMessage {
     };
   }
 
-  private generateMessageId(): string {
-    return uuidv4();
-  }
-
   private getTimestamp(): string {
     return new Date().toISOString();
   }

src/Device.ts

@@ -1,10 +1,12 @@
-import { AlexaInterface, AlexaInterfaceType } from "./AlexaInterface";
-import { DisplayCategory } from "./DisplayCategory";
+import { AlexaInterface } from "./AlexaInterface.js";
+import type { AlexaInterfaceType } from "./AlexaInterface.js";
+import { DisplayCategory } from "./DisplayCategory.js";
 import { EventEmitter } from "events";
-import { MqttClient } from "mqtt";
-import { AlexaStatusMessage, ChangeCause } from "./AlexaStatusMessage";
-import { v4 as uuidv4 } from "uuid";
-import { AlexaErrorResponse } from "./AlexaErrorResponse";
+import { randomUUID } from "crypto";
+import type { MqttClient } from "mqtt";
+import { AlexaStatusMessage } from "./AlexaStatusMessage.js";
+import type { ChangeCause } from "./AlexaStatusMessage.js";
+import { AlexaErrorResponse } from "./AlexaErrorResponse.js";
 
 class Device extends EventEmitter {
   protected softwareVersion: string = "1.0.0";
@@ -102,7 +104,7 @@ class Device extends EventEmitter {
     const payload = {
       context: {},
       event: {
-        header: { namespace: "Alexa.SceneController", name: activated ? "ActivationStarted" : "DeactivationStarted", messageId: uuidv4(), correlationToken, payloadVersion: "3" },
+        header: { namespace: "Alexa.SceneController", name: activated ? "ActivationStarted" : "DeactivationStarted", messageId: randomUUID(), correlationToken, payloadVersion: "3" },
         endpoint: { endpointId: this.endpointId },
         payload: { cause: { type: cause }, timestamp: new Date().toISOString() },
       },

src/index.ts

@@ -1,10 +1,11 @@
-export { default as Alex2MQTT, DEFAULT_HOST } from "./Alex2Node";
-export type { Alex2MQTTOptions } from "./Alex2Node";
-export { default as Device } from "./Device";
-export { AlexaInterface, AlexaInterfaceType } from "./AlexaInterface";
-export type { SupportedMode } from "./AlexaInterface";
-export { ActionMapping, AlexaActions } from "./ActionMapping";
-export { DisplayCategory } from "./DisplayCategory";
-export { AlexaStatusMessage, PowerController, EndpointHealth, TemperatureSensorScale, ThermostatMode } from "./AlexaStatusMessage";
-export type { ChangeCause } from "./AlexaStatusMessage";
-export { AlexaErrorType, AlexaErrorResponse } from "./AlexaErrorResponse";
+// Relative specifiers carry ".js": Node's ES module loader resolves no extension, and TypeScript maps it back to the .ts.
+export { default as Alex2MQTT, DEFAULT_HOST } from "./Alex2Node.js";
+export type { Alex2MQTTOptions } from "./Alex2Node.js";
+export { default as Device } from "./Device.js";
+export { AlexaInterface, AlexaInterfaceType } from "./AlexaInterface.js";
+export type { SupportedMode } from "./AlexaInterface.js";
+export { ActionMapping, AlexaActions } from "./ActionMapping.js";
+export { DisplayCategory } from "./DisplayCategory.js";
+export { AlexaStatusMessage, PowerController, EndpointHealth, TemperatureSensorScale, ThermostatMode } from "./AlexaStatusMessage.js";
+export type { ChangeCause } from "./AlexaStatusMessage.js";
+export { AlexaErrorType, AlexaErrorResponse } from "./AlexaErrorResponse.js";