diff --git a/.github/workflows/npm-publish.yml b/.github/workflows/npm-publish.yml
index cd30c058..6046ccb4 100644
--- a/.github/workflows/npm-publish.yml
+++ b/.github/workflows/npm-publish.yml
@@ -69,6 +69,19 @@ jobs:
           echo "=== arm64 prebuilds ==="
           ls -la prebuilds/linux-arm64/
 
+      - name: Install dependencies
+        # --ignore-scripts skips install/postinstall (native build + message
+        # generation need a sourced ROS env, which this job doesn't have) while
+        # still installing devDependencies such as tsup needed for build:dist.
+        run: npm install --ignore-scripts
+
+      - name: Build dist (ESM/CJS bundles)
+        # npm-pack.sh packs with --ignore-scripts, so the prepack hook that
+        # normally runs build:dist is skipped. dist/ is git-ignored and absent
+        # on a fresh checkout, so build it explicitly before packing — the
+        # published package's main/module/exports all point at ./dist/*.
+        run: npm run build:dist
+
       - name: Pack
         run: ./scripts/npm-pack.sh
 
@@ -96,7 +109,7 @@ jobs:
           fi
           if [[ "${{ inputs.dry_run }}" == "true" ]]; then
             echo "=== DRY RUN ==="
-            npm publish --provenance --access public --tag "$TAG" --dry-run ./dist/rclnodejs-*.tgz
+            npm publish --provenance --access public --tag "$TAG" --dry-run ./pack/rclnodejs-*.tgz
           else
-            npm publish --provenance --access public --tag "$TAG" ./dist/rclnodejs-*.tgz
+            npm publish --provenance --access public --tag "$TAG" ./pack/rclnodejs-*.tgz
           fi
diff --git a/.gitignore b/.gitignore
index bc101a55..4486a56c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -16,6 +16,7 @@ cpplint.py
 generated
 types/interfaces.d.ts
 dist
+pack
 build
 log
 .vscode
diff --git a/.npmignore b/.npmignore
index 70c34eae..bcaeb57e 100644
--- a/.npmignore
+++ b/.npmignore
@@ -6,6 +6,7 @@
 .gitignore
 .prettierrc.yml
 eslint.config.mjs
+tsup.config.js
 CONTRIBUTORS.md
 Dockerfile
 cpplint.py
@@ -15,9 +16,11 @@ build/
 __pycache__/
 *.pyc
 coverage/
-dist/
 log/
 install/
+pack/
+dist/package/
+dist/*.tgz
 test/
 docs/
 example/
diff --git a/README.md b/README.md
index 09cf572f..68ffea1d 100644
--- a/README.md
+++ b/README.md
@@ -105,7 +105,7 @@ npm install
 2. Run a publisher example from this checkout.
 
 ```bash
-node example/topics/publisher/publisher-example.js
+node example/topics/publisher/publisher-example.cjs
 ```
 
 More runnable examples in [example/](https://github.com/RobotWebTools/rclnodejs/tree/develop/example) and step-by-step guides in [tutorials/](./tutorials/).
diff --git a/demo/rosocket/README.md b/demo/rosocket/README.md
index 4dffa0cd..28709c61 100644
--- a/demo/rosocket/README.md
+++ b/demo/rosocket/README.md
@@ -11,12 +11,12 @@ library required.
 - Subscribe to and publish on `/chatter` (`std_msgs/msg/String`).
 - Call `/add_two_ints` (`example_interfaces/srv/AddTwoInts`) — the
   service implementation lives in
-  [`example/services/service/service-example.js`](../../example/services/service/service-example.js)
+  [`example/services/service/service-example.cjs`](../../example/services/service/service-example.cjs)
   and is launched in a second terminal.
 
 ## Layout
 
-- `server.js` — `rclnodejs` node + `startRosocket` bridge only.
+- `server.cjs` — `rclnodejs` node + `startRosocket` bridge only.
 - `index.html` — single-file browser client using only built-in
   `WebSocket` and `JSON`.
 
@@ -27,12 +27,12 @@ library required.
 source /opt/ros/$ROS_DISTRO/setup.bash
 
 # 2. Terminal A — start the WebSocket gateway
-node demo/rosocket/server.js
+node demo/rosocket/server.cjs
 # [rosocket-demo] listening on ws://localhost:9000 (bind=0.0.0.0)
 
 # 3. Terminal B — start the AddTwoInts service so the browser has
 #    something to call
-node example/services/service/service-example.js
+node example/services/service/service-example.cjs
 ```
 
 The server binds to `0.0.0.0:9000` so it is reachable from any host
diff --git a/demo/rosocket/server.js b/demo/rosocket/server.cjs
similarity index 94%
rename from demo/rosocket/server.js
rename to demo/rosocket/server.cjs
index 5f5898d1..9d11cbe4 100644
--- a/demo/rosocket/server.js
+++ b/demo/rosocket/server.cjs
@@ -17,17 +17,17 @@
 //   ws://<host>:9000/service/add_two_ints example_interfaces/srv/AddTwoInts
 //
 // Run inside WSL (where ROS 2 is sourced):
-//   node demo/rosocket/server.js
+//   node demo/rosocket/server.cjs
 //
 // To exercise the service, start the existing AddTwoInts example in a
 // second terminal (it implements `/add_two_ints`):
-//   node example/services/service/service-example.js
+//   node example/services/service/service-example.cjs
 //
 // Then open demo/rosocket/index.html on the Windows host browser. WSL2
 // forwards localhost so `ws://localhost:9000` works as-is. See README.md
 // for fallback instructions.
 
-const rclnodejs = require('../../index.js');
+const rclnodejs = require('../../index.js').default;
 const { startRosocket } = require('../../rosocket');
 
 const PORT = Number(process.env.PORT) || 9000;
diff --git a/demo/web/javascript/README.md b/demo/web/javascript/README.md
index 082ed171..46290481 100644
--- a/demo/web/javascript/README.md
+++ b/demo/web/javascript/README.md
@@ -14,12 +14,12 @@ cd demo/web/javascript
 
 ```bash
 source /opt/ros/<distro>/setup.bash
-node runtime.js
+node runtime.cjs
 # rclnodejs/web : ws://localhost:9000/capability
 #               also http://localhost:9001/capability  (call/publish, curl-able)
 ```
 
-`runtime.js` exposes a tiny `/add_two_ints` service + 1 Hz
+`runtime.cjs` exposes a tiny `/add_two_ints` service + 1 Hz
 `/web_demo_tick` publisher so every panel has live data.
 
 **Shell 2 — static-file server (hosts `index.html` + maps `/sdk/*` to
@@ -27,7 +27,7 @@ the in-repo [`web/`](../../../web/) folder so the page can `import`
 the SDK from a plain URL):**
 
 ```bash
-node static.js
+node static.cjs
 # Static files : http://localhost:8080/
 ```
 
@@ -67,18 +67,18 @@ curl -sS -X POST http://localhost:9001/capability/call/add_two_ints \
 
 Subscribe stays on WebSocket.
 
-## Without the bundled `runtime.js`
+## Without the bundled `runtime.cjs`
 
-`runtime.js` bundles the rclnodejs/web runtime and the demo's sample
+`runtime.cjs` bundles the rclnodejs/web runtime and the demo's sample
 ROS 2 nodes (the `/add_two_ints` service + the `/web_demo_tick`
 publisher) into one process so the demo runs out of the box. In a
 real project you already have those ROS 2 nodes running elsewhere,
-so you only need the runtime. **Replace shell 1's `node runtime.js`
-with the CLI** — shell 2 (`node static.js`) and the browser code are
+so you only need the runtime. **Replace shell 1's `node runtime.cjs`
+with the CLI** — shell 2 (`node static.cjs`) and the browser code are
 unchanged:
 
 ```bash
-# shell 1 (instead of `node runtime.js`); the `-p rclnodejs` tells npx
+# shell 1 (instead of `node runtime.cjs`); the `-p rclnodejs` tells npx
 # the `rclnodejs-web` binary lives inside the `rclnodejs` package:
 npx -p rclnodejs rclnodejs-web web.json
 
diff --git a/demo/web/javascript/index.html b/demo/web/javascript/index.html
index f3865598..bf5c2f37 100644
--- a/demo/web/javascript/index.html
+++ b/demo/web/javascript/index.html
@@ -1,7 +1,7 @@
 <!doctype html>
 <!--
   rclnodejs/web demo. Open via http://localhost:8080/ once both
-  `node runtime.js` (rclnodejs/web runtime) and `node static.js`
+  `node runtime.cjs` (rclnodejs/web runtime) and `node static.cjs`
   (page server) are running — see README.md.
 -->
 <html lang="en">
diff --git a/demo/web/javascript/runtime.js b/demo/web/javascript/runtime.cjs
similarity index 93%
rename from demo/web/javascript/runtime.js
rename to demo/web/javascript/runtime.cjs
index 20608007..1b598407 100644
--- a/demo/web/javascript/runtime.js
+++ b/demo/web/javascript/runtime.cjs
@@ -7,18 +7,18 @@
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // rclnodejs/web demo — runtime side (rclnodejs/web runtime + the demo's
-// ROS 2 nodes; named `runtime.js` to avoid being confused with the
-// page-side `static.js`).
+// ROS 2 nodes; named `runtime.cjs` to avoid being confused with the
+// page-side `static.cjs`).
 //
 //   1. Source ROS 2 (`source /opt/ros/<distro>/setup.bash`)
-//   2. From this folder run `node runtime.js`
-//   3. In another shell run `node static.js` to host
+//   2. From this folder run `node runtime.cjs`
+//   3. In another shell run `node static.cjs` to host
 //      `index.html` on http://localhost:8080/ — same split as the
 //      TypeScript demo's `tsx server.ts` + `vite`.
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 // In a downstream project this is the public, supported import:
 //   const { createRuntime, WebSocketTransport, HttpTransport } =
 //     require('rclnodejs/web/server');
@@ -135,7 +135,7 @@ async function main() {
   console.log(formatCapabilities(caps));
   console.log();
   console.log(
-    'Static page: run `node static.js` in another shell, then open http://localhost:8080/'
+    'Static page: run `node static.cjs` in another shell, then open http://localhost:8080/'
   );
 
   // ---- Graceful shutdown ----------------------------------------------
diff --git a/demo/web/javascript/static.js b/demo/web/javascript/static.cjs
similarity index 95%
rename from demo/web/javascript/static.js
rename to demo/web/javascript/static.cjs
index 7bd92c0f..b0380e63 100644
--- a/demo/web/javascript/static.js
+++ b/demo/web/javascript/static.cjs
@@ -6,15 +6,15 @@
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
-// rclnodejs/web demo — static-file server (page side; named `static.js`
-// to avoid being confused with the runtime-side `runtime.js`).
+// rclnodejs/web demo — static-file server (page side; named `static.cjs`
+// to avoid being confused with the runtime-side `runtime.cjs`).
 //
 // Serves index.html on port 8080 and maps `/sdk/*` to the in-repo
 // `web/` folder so the page can `import { connect } from '/sdk/index.js'`
 // without bundling. In a downstream project you'd `npm install rclnodejs`
 // and `import { connect } from 'rclnodejs/web'` instead.
 //
-// Pair with `node runtime.js` (the rclnodejs/web runtime + the demo's
+// Pair with `node runtime.cjs` (the rclnodejs/web runtime + the demo's
 // ROS 2 nodes) in another shell — the same split as the TypeScript
 // demo's `tsx server.ts` + `vite`. Production deployments use nginx,
 // a CDN, or any other static host.
diff --git a/demo/web/typescript/server.ts b/demo/web/typescript/server.ts
index 462aa890..649e1cf4 100644
--- a/demo/web/typescript/server.ts
+++ b/demo/web/typescript/server.ts
@@ -7,11 +7,11 @@
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // TypeScript demo server. Run with `npm run server` (which uses tsx) or
-// `npx tsx server.ts`. Behaviour matches demo/web/javascript/runtime.js
+// `npx tsx server.ts`. Behaviour matches demo/web/javascript/runtime.cjs
 // — same runtime + same demo nodes — except this side is written in
 // TypeScript so the typed SDK story is visible end to end. The static
 // page server is Vite (`npm run dev`), parallel to the JS demo's
-// separate `node static.js`.
+// separate `node static.cjs`.
 
 // rclnodejs is a CommonJS module without first-class ESM types; using
 // require keeps the server independent of how a downstream project
@@ -30,7 +30,7 @@ const RUNTIME_PORT = Number(process.env.RUNTIME_PORT || 9000);
 const HTTP_PORT = Number(process.env.HTTP_PORT || 9001);
 
 // Render the registry as a small human-readable table — see the matching
-// helper in demo/web/javascript/runtime.js.
+// helper in demo/web/javascript/runtime.cjs.
 function formatCapabilities(
   caps: Record<'call' | 'publish' | 'subscribe', Record<string, string>>
 ): string {
diff --git a/eslint.config.mjs b/eslint.config.mjs
index dbaa5b67..0605dc20 100644
--- a/eslint.config.mjs
+++ b/eslint.config.mjs
@@ -61,7 +61,7 @@ export default [
             ecmaVersion: "latest",
             sourceType: "module",
         },
-        files: ["lib/**/*.js", "test/**/*.js", "bin/**/*.js", "rosocket/**/*.js", "index.js"],
+        files: ["lib/**/*.js", "test/**/*.js", "bin/**/*.js", "rosocket/**/*.js", "index.js", "example/**/*.mjs"],
         rules: {
             ...eslintPluginPrettierRecommended.rules,
         },
@@ -78,7 +78,7 @@ export default [
             sourceType: "commonjs",
         },
         files: ["rosidl_parser/**/*.{js,cjs}", "rosidl_gen/**/*.{js,cjs}",
-            "rostsd_gen/**/*.{js,cjs}", "example/**/*.js"],
+            "rostsd_gen/**/*.{js,cjs}", "example/**/*.cjs"],
         rules: {
             ...eslintPluginPrettierRecommended.rules,
         },
diff --git a/example/actions/README.md b/example/actions/README.md
index d2a3f583..f257c708 100644
--- a/example/actions/README.md
+++ b/example/actions/README.md
@@ -24,7 +24,7 @@ Actions are ideal for:
 
 The `action_client/` directory contains examples of nodes that send goals to action servers:
 
-#### 1. Basic Action Client (`action-client-example.js`)
+#### 1. Basic Action Client (`action-client-example.cjs`)
 
 **Purpose**: Demonstrates basic action client functionality with the Fibonacci action.
 
@@ -40,9 +40,9 @@ The `action_client/` directory contains examples of nodes that send goals to act
   - Goal acceptance verification
   - Feedback handling during execution
   - Result processing with status checking
-- **Run Command**: `node action_client/action-client-example.js`
+- **Run Command**: `node action_client/action-client-example.cjs`
 
-#### 2. Action Client with Cancellation (`action-client-cancel-example.js`)
+#### 2. Action Client with Cancellation (`action-client-cancel-example.cjs`)
 
 **Purpose**: Demonstrates how to cancel an action goal during execution.
 
@@ -58,9 +58,9 @@ The `action_client/` directory contains examples of nodes that send goals to act
   - Goal cancellation with `cancelGoal()`
   - Cancellation response verification
   - Cleanup and shutdown handling
-- **Run Command**: `node action_client/action-client-cancel-example.js`
+- **Run Command**: `node action_client/action-client-cancel-example.cjs`
 
-#### 3. Action Client Validation (`action-client-validation-example.js`)
+#### 3. Action Client Validation (`action-client-validation-example.cjs`)
 
 **Purpose**: Demonstrates goal validation features for action clients.
 
@@ -80,14 +80,14 @@ The `action_client/` directory contains examples of nodes that send goals to act
   - **Detailed Errors**: Field-level validation issues with expected vs received types
   - **Strict Mode**: Detect extra fields that don't belong in the goal
   - **Reusable Validators**: Create validators for repeated goal validation
-- **Run Command**: `node action_client/action-client-validation-example.js`
+- **Run Command**: `node action_client/action-client-validation-example.cjs`
 - **Note**: Standalone example - demonstrates validation errors without requiring a running action server
 
 ### Action Server Examples
 
 The `action_server/` directory contains examples of nodes that provide action services:
 
-#### 1. Basic Action Server (`action-server-example.js`)
+#### 1. Basic Action Server (`action-server-example.cjs`)
 
 **Purpose**: Demonstrates basic action server implementation for computing Fibonacci sequences.
 
@@ -103,9 +103,9 @@ The `action_server/` directory contains examples of nodes that provide action se
   - Execution callback with feedback publishing
   - Cancellation handling (`cancelCallback`)
   - Progress updates every second
-- **Run Command**: `node action_server/action-server-example.js`
+- **Run Command**: `node action_server/action-server-example.cjs`
 
-#### 2. Deferred Execution Server (`action-server-defer-example.js`)
+#### 2. Deferred Execution Server (`action-server-defer-example.cjs`)
 
 **Purpose**: Shows how to defer goal execution using timers and handle accepted callbacks.
 
@@ -121,9 +121,9 @@ The `action_server/` directory contains examples of nodes that provide action se
   - Handle accepted callback (`handleAcceptedCallback`)
   - Timer-based execution control
   - Manual goal execution triggering
-- **Run Command**: `node action_server/action-server-defer-example.js`
+- **Run Command**: `node action_server/action-server-defer-example.cjs`
 
-#### 3. Single Goal Server (`action-server-single-goal-example.js`)
+#### 3. Single Goal Server (`action-server-single-goal-example.cjs`)
 
 **Purpose**: Demonstrates a server that only allows one active goal at a time.
 
@@ -139,7 +139,7 @@ The `action_server/` directory contains examples of nodes that provide action se
   - Automatic abortion of previous goals
   - Goal state tracking (`isActive`)
   - Handle accepted callback for goal management
-- **Run Command**: `node action_server/action-server-single-goal-example.js`
+- **Run Command**: `node action_server/action-server-single-goal-example.cjs`
 
 ## How to Run the Examples
 
@@ -156,7 +156,7 @@ The `action_server/` directory contains examples of nodes that provide action se
 
    ```bash
    cd example/actions
-   node action_server/action-server-example.js
+   node action_server/action-server-example.cjs
    ```
 
    You should see:
@@ -169,7 +169,7 @@ The `action_server/` directory contains examples of nodes that provide action se
 
    ```bash
    cd example/actions
-   node action_client/action-client-example.js
+   node action_client/action-client-example.cjs
    ```
 
 3. **Expected Output**:
@@ -203,14 +203,14 @@ The `action_server/` directory contains examples of nodes that provide action se
 1. **Start Server**: Run any action server example
 2. **Start Cancellation Client**:
    ```bash
-   node action_client/action-client-cancel-example.js
+   node action_client/action-client-cancel-example.cjs
    ```
 3. **Expected Behavior**: Client sends goal, receives feedback for 2 seconds, then cancels
 
 #### Specialized Server Examples
 
-- **Deferred Execution**: Use `action-server-defer-example.js` to see 3-second execution delay
-- **Single Goal**: Use `action-server-single-goal-example.js` to test goal abortion behavior
+- **Deferred Execution**: Use `action-server-defer-example.cjs` to see 3-second execution delay
+- **Single Goal**: Use `action-server-single-goal-example.cjs` to test goal abortion behavior
 
 ## Action Components Explained
 
diff --git a/example/actions/action_client/action-client-cancel-example.js b/example/actions/action_client/action-client-cancel-example.cjs
similarity index 97%
rename from example/actions/action_client/action-client-cancel-example.js
rename to example/actions/action_client/action-client-cancel-example.cjs
index 272d5459..abc70aaf 100644
--- a/example/actions/action_client/action-client-cancel-example.js
+++ b/example/actions/action_client/action-client-cancel-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 const Fibonacci = rclnodejs.require('test_msgs/action/Fibonacci');
 
 class FibonacciActionClient {
diff --git a/example/actions/action_client/action-client-example.js b/example/actions/action_client/action-client-example.cjs
similarity index 97%
rename from example/actions/action_client/action-client-example.js
rename to example/actions/action_client/action-client-example.cjs
index 18211379..47e33046 100644
--- a/example/actions/action_client/action-client-example.js
+++ b/example/actions/action_client/action-client-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 const Fibonacci = rclnodejs.require('test_msgs/action/Fibonacci');
 
 class FibonacciActionClient {
diff --git a/example/actions/action_client/action-client-validation-example.js b/example/actions/action_client/action-client-validation-example.cjs
similarity index 96%
rename from example/actions/action_client/action-client-validation-example.js
rename to example/actions/action_client/action-client-validation-example.cjs
index aa8a3f4a..880afd59 100644
--- a/example/actions/action_client/action-client-validation-example.js
+++ b/example/actions/action_client/action-client-validation-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 
 async function main() {
   await rclnodejs.init();
diff --git a/example/actions/action_server/action-server-defer-example.js b/example/actions/action_server/action-server-defer-example.cjs
similarity index 98%
rename from example/actions/action_server/action-server-defer-example.js
rename to example/actions/action_server/action-server-defer-example.cjs
index 5a2768f3..99e75ec8 100644
--- a/example/actions/action_server/action-server-defer-example.js
+++ b/example/actions/action_server/action-server-defer-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 const Fibonacci = rclnodejs.require('test_msgs/action/Fibonacci');
 
 class FibonacciActionServer {
diff --git a/example/actions/action_server/action-server-example.js b/example/actions/action_server/action-server-example.cjs
similarity index 97%
rename from example/actions/action_server/action-server-example.js
rename to example/actions/action_server/action-server-example.cjs
index e61c9886..8e4da1a8 100644
--- a/example/actions/action_server/action-server-example.js
+++ b/example/actions/action_server/action-server-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 const Fibonacci = rclnodejs.require('test_msgs/action/Fibonacci');
 
 class FibonacciActionServer {
diff --git a/example/actions/action_server/action-server-single-goal-example.js b/example/actions/action_server/action-server-single-goal-example.cjs
similarity index 98%
rename from example/actions/action_server/action-server-single-goal-example.js
rename to example/actions/action_server/action-server-single-goal-example.cjs
index ab993baa..6ff88d2e 100644
--- a/example/actions/action_server/action-server-single-goal-example.js
+++ b/example/actions/action_server/action-server-single-goal-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 const Fibonacci = rclnodejs.require('test_msgs/action/Fibonacci');
 
 class FibonacciActionServer {
diff --git a/example/error-handling/README.md b/example/error-handling/README.md
index 8990e6ad..5c15ffa4 100644
--- a/example/error-handling/README.md
+++ b/example/error-handling/README.md
@@ -34,7 +34,7 @@ RclNodeError (base)
 
 ## Examples
 
-### 1. Type Validation (`error-handling-example.js` - Example 1)
+### 1. Type Validation (`error-handling-example.cjs` - Example 1)
 
 **Purpose**: Demonstrates catching `TypeValidationError` when providing wrong argument types.
 
@@ -42,7 +42,7 @@ RclNodeError (base)
 - **Features**: Shows `argumentName`, `expectedType`, and `providedValue` properties
 - **Key Properties**: `error.argumentName`, `error.expectedType`, `error.providedValue`
 
-### 2. Range Validation (`error-handling-example.js` - Example 2)
+### 2. Range Validation (`error-handling-example.cjs` - Example 2)
 
 **Purpose**: Demonstrates catching `RangeValidationError` for out-of-bounds values.
 
@@ -50,7 +50,7 @@ RclNodeError (base)
 - **Features**: Shows `validationRule` and `providedValue` for constraint violations
 - **Key Properties**: `error.validationRule`, `error.providedValue`, `error.nodeName`
 
-### 3. Service Errors (`error-handling-example.js` - Example 3)
+### 3. Service Errors (`error-handling-example.cjs` - Example 3)
 
 **Purpose**: Demonstrates `TimeoutError` and `AbortError` handling for service operations.
 
@@ -58,7 +58,7 @@ RclNodeError (base)
 - **Features**: Demonstrates timeout with `sendRequestAsync({ timeout })` and `AbortController`
 - **Key Properties**: `error.timeout`, `error.operationType`, `error.entityName`
 
-### 4. Publisher Errors (`error-handling-example.js` - Example 4)
+### 4. Publisher Errors (`error-handling-example.cjs` - Example 4)
 
 **Purpose**: Demonstrates catching `PublisherError` during publisher creation.
 
@@ -66,7 +66,7 @@ RclNodeError (base)
 - **Features**: Shows error handling for topic creation failures
 - **Key Class**: `PublisherError`
 
-### 5. Subscription Errors (`error-handling-example.js` - Example 5)
+### 5. Subscription Errors (`error-handling-example.cjs` - Example 5)
 
 **Purpose**: Demonstrates catching `SubscriptionError` during subscription creation.
 
@@ -74,7 +74,7 @@ RclNodeError (base)
 - **Features**: Shows error handling for subscription creation failures
 - **Key Class**: `SubscriptionError`
 
-### 6. Parameter Errors (`error-handling-example.js` - Example 6)
+### 6. Parameter Errors (`error-handling-example.cjs` - Example 6)
 
 **Purpose**: Demonstrates `ParameterTypeError` for parameter type mismatches.
 
@@ -82,7 +82,7 @@ RclNodeError (base)
 - **Features**: Shows parameter validation and type checking
 - **Key Class**: `ParameterTypeError`
 
-### 7. Name Validation (`error-handling-example.js` - Example 7)
+### 7. Name Validation (`error-handling-example.cjs` - Example 7)
 
 **Purpose**: Demonstrates `NameValidationError` for invalid ROS names.
 
@@ -90,7 +90,7 @@ RclNodeError (base)
 - **Features**: Shows `invalidIndex` property pointing to error location
 - **Key Properties**: `error.invalidIndex`, `error.message`
 
-### 8. Error Recovery (`error-handling-example.js` - Example 8)
+### 8. Error Recovery (`error-handling-example.cjs` - Example 8)
 
 **Purpose**: Demonstrates retry logic with structured error handling.
 
@@ -98,7 +98,7 @@ RclNodeError (base)
 - **Features**: Shows differentiation between recoverable and non-recoverable errors
 - **Pattern**: Retry on `TimeoutError`, abort on `AbortError` or other errors
 
-### 9. Error Serialization (`error-handling-example.js` - Example 9)
+### 9. Error Serialization (`error-handling-example.cjs` - Example 9)
 
 **Purpose**: Demonstrates using `toJSON()` for logging and debugging.
 
@@ -106,7 +106,7 @@ RclNodeError (base)
 - **Features**: Shows `toJSON()` method producing complete error information
 - **Method**: `error.toJSON()`
 
-### 10. Generic Error Handler (`error-handling-example.js` - Example 10)
+### 10. Generic Error Handler (`error-handling-example.cjs` - Example 10)
 
 **Purpose**: Demonstrates reusable error handler for all rclnodejs errors.
 
@@ -121,7 +121,7 @@ RclNodeError (base)
 2. **Run All Examples**:
 
    ```bash
-   node example/error-handling/error-handling-example.js
+   node example/error-handling/error-handling-example.cjs
    ```
 
 3. **Expected Output**: Demonstrates all 10 error handling patterns with clear success indicators
diff --git a/example/error-handling/error-handling-example.js b/example/error-handling/error-handling-example.cjs
similarity index 99%
rename from example/error-handling/error-handling-example.js
rename to example/error-handling/error-handling-example.cjs
index a20c1e7d..e2549ad9 100644
--- a/example/error-handling/error-handling-example.js
+++ b/example/error-handling/error-handling-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../index.js');
+const rclnodejs = require('../../index.js').default;
 
 /**
  * Example 1: Type Validation Errors
diff --git a/example/graph/README.md b/example/graph/README.md
index 7ada5bdd..8fca619f 100644
--- a/example/graph/README.md
+++ b/example/graph/README.md
@@ -22,7 +22,7 @@ Graph introspection allows you to:
 
 ## Graph Example
 
-### ROS Graph Discovery (`ros-graph-example.js`)
+### ROS Graph Discovery (`ros-graph-example.cjs`)
 
 **Purpose**: Demonstrates comprehensive ROS 2 graph introspection capabilities.
 
@@ -61,7 +61,7 @@ This example creates a complete ROS 2 system with multiple nodes and then intros
 #### Run Command
 
 ```bash
-node ros-graph-example.js
+node ros-graph-example.cjs
 ```
 
 ## Sample Output
diff --git a/example/graph/ros-graph-example.js b/example/graph/ros-graph-example.cjs
similarity index 98%
rename from example/graph/ros-graph-example.js
rename to example/graph/ros-graph-example.cjs
index 9039b86a..f179a624 100644
--- a/example/graph/ros-graph-example.js
+++ b/example/graph/ros-graph-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../index.js');
+const rclnodejs = require('../../index.js').default;
 
 console.log(
   'This example creates the following nodes and outputs the corresponding ROS2 graph:'
diff --git a/example/lifecycle/README.md b/example/lifecycle/README.md
index 628e78e9..2cf36489 100644
--- a/example/lifecycle/README.md
+++ b/example/lifecycle/README.md
@@ -38,7 +38,7 @@ State transitions are triggered by these transitions:
 
 ## Lifecycle Example
 
-### Lifecycle Node with Countdown (`lifecycle-node-example.js`)
+### Lifecycle Node with Countdown (`lifecycle-node-example.cjs`)
 
 **Purpose**: Demonstrates a complete lifecycle node implementation with automated state management.
 
@@ -81,7 +81,7 @@ This example creates a lifecycle node that:
 #### Run Command
 
 ```bash
-node lifecycle-node-example.js
+node lifecycle-node-example.cjs
 ```
 
 ## Sample Output
diff --git a/example/lifecycle/lifecycle-node-example.js b/example/lifecycle/lifecycle-node-example.cjs
similarity index 98%
rename from example/lifecycle/lifecycle-node-example.js
rename to example/lifecycle/lifecycle-node-example.cjs
index 905895be..5a89fe67 100644
--- a/example/lifecycle/lifecycle-node-example.js
+++ b/example/lifecycle/lifecycle-node-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../index.js');
+const rclnodejs = require('../../index.js').default;
 
 const NODE_NAME = 'test_node';
 const TOPIC = 'test';
diff --git a/example/message-introspector/README.md b/example/message-introspector/README.md
index b2319ca8..cd4796ad 100644
--- a/example/message-introspector/README.md
+++ b/example/message-introspector/README.md
@@ -6,14 +6,14 @@ This directory contains an example demonstrating the `MessageIntrospector` class
 
 The `MessageIntrospector` class provides a simple way to understand the structure of ROS 2 messages without directly using `loader.loadInterface`. It's useful for debugging, generating documentation, and building dynamic UIs based on message structure.
 
-## MessageIntrospector Example (`message-introspector-example.js`)
+## MessageIntrospector Example (`message-introspector-example.cjs`)
 
 **Purpose**: Demonstrates how to inspect message structure, fields, and default values.
 
 ### Run Command
 
 ```bash
-node message-introspector-example.js
+node message-introspector-example.cjs
 ```
 
 ### Expected Output
diff --git a/example/message-introspector/message-introspector-example.js b/example/message-introspector/message-introspector-example.cjs
similarity index 96%
rename from example/message-introspector/message-introspector-example.js
rename to example/message-introspector/message-introspector-example.cjs
index 45c9d24f..484131dc 100644
--- a/example/message-introspector/message-introspector-example.js
+++ b/example/message-introspector/message-introspector-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../index.js');
+const rclnodejs = require('../../index.js').default;
 
 /**
  * This example demonstrates the MessageIntrospector class for
diff --git a/example/parameter/README.md b/example/parameter/README.md
index 7bb691d5..7c9d548d 100644
--- a/example/parameter/README.md
+++ b/example/parameter/README.md
@@ -22,7 +22,7 @@ Parameters are ideal for:
 
 ### Local Parameters (On Current Node)
 
-#### 1. Parameter Declaration (`parameter-declaration-example.js`)
+#### 1. Parameter Declaration (`parameter-declaration-example.cjs`)
 
 **Purpose**: Demonstrates how to declare and use parameters in a ROS 2 node.
 
@@ -41,9 +41,9 @@ Parameters are ideal for:
   - **Name**: `param1`
   - **Type**: `PARAMETER_STRING`
   - **Default Value**: `"hello world"`
-- **Run Command**: `node parameter-declaration-example.js`
+- **Run Command**: `node parameter-declaration-example.cjs`
 
-#### 2. Parameter Override (`parameter-override-example.js`)
+#### 2. Parameter Override (`parameter-override-example.cjs`)
 
 **Purpose**: Shows how to override parameter values using command-line arguments.
 
@@ -63,11 +63,11 @@ Parameters are ideal for:
   - **Type**: `PARAMETER_STRING`
   - **Default Value**: `"hello world"`
   - **Override Value**: `"hello ros2"` (via command line)
-- **Run Command**: `node parameter-override-example.js`
+- **Run Command**: `node parameter-override-example.cjs`
 
 ### Remote Parameter Access (On Other Nodes)
 
-#### 3. ParameterClient Basic (`parameter-client-basic-example.js`)
+#### 3. ParameterClient Basic (`parameter-client-basic-example.cjs`)
 
 **Purpose**: Demonstrates accessing and modifying parameters on a remote node using `ParameterClient`.
 
@@ -84,9 +84,9 @@ Parameters are ideal for:
   - Batch parameter retrieval
   - Automatic type inference for parameter values
 - **Target Node**: `turtlesim` (run: `ros2 run turtlesim turtlesim_node`)
-- **Run Command**: `node parameter-client-basic-example.js`
+- **Run Command**: `node parameter-client-basic-example.cjs`
 
-#### 4. ParameterClient Advanced (`parameter-client-advanced-example.js`)
+#### 4. ParameterClient Advanced (`parameter-client-advanced-example.cjs`)
 
 **Purpose**: Comprehensive example showing all ParameterClient features and capabilities.
 
@@ -108,9 +108,9 @@ Parameters are ideal for:
   - Automatic BigInt conversion for integers
   - Type inference demonstrations
   - Lifecycle management
-- **Run Command**: `node parameter-client-advanced-example.js`
+- **Run Command**: `node parameter-client-advanced-example.cjs`
 
-#### 5. ParameterWatcher (`parameter-watcher-example.js`)
+#### 5. ParameterWatcher (`parameter-watcher-example.cjs`)
 
 **Purpose**: Demonstrates watching parameter changes on a remote node in real-time.
 
@@ -126,7 +126,7 @@ Parameters are ideal for:
   - Built on top of ParameterClient
   - Simple EventEmitter API
 - **Target Node**: `turtlesim` (run: `ros2 run turtlesim turtlesim_node`)
-- **Run Command**: `node parameter-watcher-example.js`
+- **Run Command**: `node parameter-watcher-example.cjs`
 - **Test Changes**: In another terminal, run `ros2 param set /turtlesim background_r 200`
 
 **ParameterClient Key Features**:
@@ -184,7 +184,7 @@ Parameters are ideal for:
 
 ```bash
 cd example/parameter
-node parameter-declaration-example.js
+node parameter-declaration-example.cjs
 ```
 
 **Expected Output**:
@@ -212,7 +212,7 @@ ParameterDescriptor {
 
 ```bash
 cd example/parameter
-node parameter-override-example.js
+node parameter-override-example.cjs
 ```
 
 **Expected Output**:
@@ -250,7 +250,7 @@ Then in another terminal:
 
 ```bash
 cd example/parameter
-node parameter-client-basic-example.js
+node parameter-client-basic-example.cjs
 ```
 
 **Expected Output**:
@@ -264,7 +264,7 @@ Updated background_b: 200n
 
 ```bash
 cd example/parameter
-node parameter-client-advanced-example.js
+node parameter-client-advanced-example.cjs
 ```
 
 **Expected Output**:
@@ -297,7 +297,7 @@ Then in another terminal:
 
 ```bash
 cd example/parameter
-node parameter-watcher-example.js
+node parameter-watcher-example.cjs
 ```
 
 **Expected Output**:
diff --git a/example/parameter/parameter-client-advanced-example.js b/example/parameter/parameter-client-advanced-example.cjs
similarity index 98%
rename from example/parameter/parameter-client-advanced-example.js
rename to example/parameter/parameter-client-advanced-example.cjs
index 0e03dfbc..ccc00106 100644
--- a/example/parameter/parameter-client-advanced-example.js
+++ b/example/parameter/parameter-client-advanced-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../index.js');
+const rclnodejs = require('../../index.js').default;
 
 const { ParameterType, Parameter, ParameterDescriptor } = rclnodejs;
 
diff --git a/example/parameter/parameter-client-basic-example.js b/example/parameter/parameter-client-basic-example.cjs
similarity index 96%
rename from example/parameter/parameter-client-basic-example.js
rename to example/parameter/parameter-client-basic-example.cjs
index f7424227..0a725dd3 100644
--- a/example/parameter/parameter-client-basic-example.js
+++ b/example/parameter/parameter-client-basic-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../index.js');
+const rclnodejs = require('../../index.js').default;
 
 async function main() {
   await rclnodejs.init();
diff --git a/example/parameter/parameter-declaration-example.js b/example/parameter/parameter-declaration-example.cjs
similarity index 96%
rename from example/parameter/parameter-declaration-example.js
rename to example/parameter/parameter-declaration-example.cjs
index d2ef5efd..ab85c11e 100644
--- a/example/parameter/parameter-declaration-example.js
+++ b/example/parameter/parameter-declaration-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../index.js');
+const rclnodejs = require('../../index.js').default;
 
 const ParameterType = rclnodejs.ParameterType;
 const Parameter = rclnodejs.Parameter;
diff --git a/example/parameter/parameter-override-example.js b/example/parameter/parameter-override-example.cjs
similarity index 96%
rename from example/parameter/parameter-override-example.js
rename to example/parameter/parameter-override-example.cjs
index e3f76897..1fce85b1 100644
--- a/example/parameter/parameter-override-example.js
+++ b/example/parameter/parameter-override-example.cjs
@@ -10,7 +10,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../index.js');
+const rclnodejs = require('../../index.js').default;
 
 const ParameterType = rclnodejs.ParameterType;
 const Parameter = rclnodejs.Parameter;
diff --git a/example/parameter/parameter-watcher-example.js b/example/parameter/parameter-watcher-example.cjs
similarity index 96%
rename from example/parameter/parameter-watcher-example.js
rename to example/parameter/parameter-watcher-example.cjs
index 5edfc775..c178ce27 100644
--- a/example/parameter/parameter-watcher-example.js
+++ b/example/parameter/parameter-watcher-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../index.js');
+const rclnodejs = require('../../index.js').default;
 
 async function main() {
   await rclnodejs.init();
diff --git a/example/rate/README.md b/example/rate/README.md
index 685e535e..52eb7e7a 100644
--- a/example/rate/README.md
+++ b/example/rate/README.md
@@ -22,7 +22,7 @@ Rate control is essential for:
 
 ## Rate Example
 
-### Rate-Limited Loop with High-Frequency Publisher (`rate-example.js`)
+### Rate-Limited Loop with High-Frequency Publisher (`rate-example.cjs`)
 
 **Purpose**: Demonstrates rate control in a scenario with mismatched publication and processing frequencies.
 
@@ -62,7 +62,7 @@ This example creates a sophisticated timing demonstration that shows:
 #### Run Command
 
 ```bash
-node rate-example.js
+node rate-example.cjs
 ```
 
 ## Sample Output
diff --git a/example/rate/rate-example.js b/example/rate/rate-example.cjs
similarity index 96%
rename from example/rate/rate-example.js
rename to example/rate/rate-example.cjs
index 527f6ec5..cafce0d8 100644
--- a/example/rate/rate-example.js
+++ b/example/rate/rate-example.cjs
@@ -12,7 +12,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../index.js');
+const rclnodejs = require('../../index.js').default;
 
 /**
  * This example demonstrates a rate limited loop running at
diff --git a/example/rosidl/README.md b/example/rosidl/README.md
index 1cefc448..e441acbf 100644
--- a/example/rosidl/README.md
+++ b/example/rosidl/README.md
@@ -23,7 +23,7 @@ ROSIDL parsing is useful for:
 
 ## ROSIDL Examples
 
-### 1. Message Parsing (`rosidl-parse-msg-example.js`)
+### 1. Message Parsing (`rosidl-parse-msg-example.cjs`)
 
 **Purpose**: Demonstrates parsing ROS 2 message definition files (.msg).
 
@@ -63,7 +63,7 @@ float32 a  # Alpha (transparency) component
 #### Run Command
 
 ```bash
-node rosidl-parse-msg-example.js
+node rosidl-parse-msg-example.cjs
 ```
 
 #### Expected Output
@@ -105,7 +105,7 @@ fields includes:
 }
 ```
 
-### 2. Service Parsing (`rosidl-parse-srv-example.js`)
+### 2. Service Parsing (`rosidl-parse-srv-example.cjs`)
 
 **Purpose**: Demonstrates parsing ROS 2 service definition files (.srv).
 
@@ -147,7 +147,7 @@ string message  # Informational message
 #### Run Command
 
 ```bash
-node rosidl-parse-srv-example.js
+node rosidl-parse-srv-example.cjs
 ```
 
 #### Expected Output
@@ -183,7 +183,7 @@ srv response fields includes:
 }
 ```
 
-### 3. Action Parsing (`rosidl-parse-action-example.js`)
+### 3. Action Parsing (`rosidl-parse-action-example.cjs`)
 
 **Purpose**: Demonstrates parsing ROS 2 action definition files (.action).
 
@@ -227,7 +227,7 @@ int32[] partial_sequence  # Partial sequence (feedback)
 #### Run Command
 
 ```bash
-node rosidl-parse-action-example.js
+node rosidl-parse-action-example.cjs
 ```
 
 #### Expected Output
@@ -289,7 +289,7 @@ Each parsed field contains these properties:
 ### Message Parsing
 
 ```javascript
-const parser = require('../rosidl_parser/rosidl_parser.js');
+const parser = require('../rosidl_parser/rosidl_parser.cjs');
 
 parser.parseMessageFile(packageName, packagePath).then((spec) => {
   console.log(`Message: ${spec.msgName}`);
diff --git a/example/rosidl/rosidl-parse-action-example.js b/example/rosidl/rosidl-parse-action-example.cjs
similarity index 100%
rename from example/rosidl/rosidl-parse-action-example.js
rename to example/rosidl/rosidl-parse-action-example.cjs
diff --git a/example/rosidl/rosidl-parse-msg-example.js b/example/rosidl/rosidl-parse-msg-example.cjs
similarity index 100%
rename from example/rosidl/rosidl-parse-msg-example.js
rename to example/rosidl/rosidl-parse-msg-example.cjs
diff --git a/example/rosidl/rosidl-parse-srv-example.js b/example/rosidl/rosidl-parse-srv-example.cjs
similarity index 100%
rename from example/rosidl/rosidl-parse-srv-example.js
rename to example/rosidl/rosidl-parse-srv-example.cjs
diff --git a/example/services/README.md b/example/services/README.md
index 09027cc1..3f52e5b3 100644
--- a/example/services/README.md
+++ b/example/services/README.md
@@ -15,7 +15,7 @@ ROS 2 services provide a request-response communication pattern where clients se
 
 ### AddTwoInts Service
 
-#### Service Server (`service/service-example.js`)
+#### Service Server (`service/service-example.cjs`)
 
 **Purpose**: Demonstrates creating a service server that adds two integers.
 
@@ -29,9 +29,9 @@ ROS 2 services provide a request-response communication pattern where clients se
 - **Features**:
   - Service introspection (ROS 2 Iron+) for monitoring service calls
   - Proper response handling using `response.template` and `response.send()`
-- **Run Command**: `node example/services/service/service-example.js`
+- **Run Command**: `node example/services/service/service-example.cjs`
 
-#### Service Client (`client/client-example.js`)
+#### Service Client (`client/client-example.cjs`)
 
 **Purpose**: Demonstrates creating a service client that sends requests to the AddTwoInts service.
 
@@ -46,9 +46,9 @@ ROS 2 services provide a request-response communication pattern where clients se
   - Service availability checking with `waitForService()`
   - Service introspection configuration (ROS 2 Iron+)
   - Asynchronous request handling with callbacks
-- **Run Command**: `node example/services/client/client-example.js`
+- **Run Command**: `node example/services/client/client-example.cjs`
 
-#### Async Service Client (`client/async-client-example.js`)
+#### Async Service Client (`client/async-client-example.cjs`)
 
 **Purpose**: Demonstrates modern async/await patterns for service communication, solving callback hell and providing cleaner error handling.
 
@@ -68,9 +68,9 @@ ROS 2 services provide a request-response communication pattern where clients se
   - **Error Types**: Specific error types (`TimeoutError`, `AbortError`) for better error handling (async only)
   - **Backward Compatible**: Works alongside existing callback-based `sendRequest()`
   - **TypeScript Ready**: Full type safety with comprehensive TypeScript definitions
-- **Run Command**: `node example/services/client/async-client-example.js`
+- **Run Command**: `node example/services/client/async-client-example.cjs`
 
-#### Service Client Validation (`client/client-validation-example.js`)
+#### Service Client Validation (`client/client-validation-example.cjs`)
 
 **Purpose**: Demonstrates request validation features for service clients.
 
@@ -89,7 +89,7 @@ ROS 2 services provide a request-response communication pattern where clients se
   - **Dynamic Toggle**: Enable/disable validation with `willValidateRequest` property
   - **Detailed Errors**: Field-level validation issues with expected vs received types
   - **Strict Mode**: Detect extra fields that don't belong in the request
-- **Run Command**: `node example/services/client/client-validation-example.js`
+- **Run Command**: `node example/services/client/client-validation-example.cjs`
 - **Note**: Standalone example - demonstrates validation errors without requiring a running service
 
 **Key API Differences**:
@@ -129,7 +129,7 @@ try {
 
 ### GetMap Service
 
-#### Service Server (`service/getmap-service-example.js`)
+#### Service Server (`service/getmap-service-example.cjs`)
 
 **Purpose**: Demonstrates creating a service server that provides occupancy grid map data.
 
@@ -145,9 +145,9 @@ try {
   - Realistic navigation map data for robotics applications
   - Service introspection support (ROS 2 Iron+)
   - Detailed logging of map properties
-- **Run Command**: `node example/services/service/getmap-service-example.js`
+- **Run Command**: `node example/services/service/getmap-service-example.cjs`
 
-#### Service Client (`client/getmap-client-example.js`)
+#### Service Client (`client/getmap-client-example.cjs`)
 
 **Purpose**: Demonstrates creating a service client that requests map data from the GetMap service.
 
@@ -163,7 +163,7 @@ try {
   - Map data analysis (cell distribution, metadata extraction)
   - Educational output showing map properties
   - Visual representation of map data
-- **Run Command**: `node example/services/client/getmap-client-example.js`
+- **Run Command**: `node example/services/client/getmap-client-example.cjs`
 
 ## How to Run the Examples
 
@@ -175,7 +175,7 @@ try {
 
    ```bash
    cd /path/to/rclnodejs
-   node example/services/service/service-example.js
+   node example/services/service/service-example.cjs
    ```
 
    You should see:
@@ -188,7 +188,7 @@ try {
 
    ```bash
    cd /path/to/rclnodejs
-   node example/services/client/client-example.js
+   node example/services/client/client-example.cjs
    ```
 
 4. **Expected Output**:
@@ -216,14 +216,14 @@ try {
 
    ```bash
    cd /path/to/rclnodejs
-   node example/services/service/service-example.js
+   node example/services/service/service-example.cjs
    ```
 
 3. **Start the Async Client**: In another terminal, run:
 
    ```bash
    cd /path/to/rclnodejs
-   node example/services/client/async-client-example.js
+   node example/services/client/async-client-example.cjs
    ```
 
 4. **Expected Output**:
@@ -251,7 +251,7 @@ try {
 
    ```bash
    cd /path/to/rclnodejs
-   node example/services/service/getmap-service-example.js
+   node example/services/service/getmap-service-example.cjs
    ```
 
    You should see:
@@ -266,7 +266,7 @@ try {
 
    ```bash
    cd /path/to/rclnodejs
-   node example/services/client/getmap-client-example.js
+   node example/services/client/getmap-client-example.cjs
    ```
 
 4. **Expected Output**:
diff --git a/example/services/client/async-client-example.js b/example/services/client/async-client-example.cjs
similarity index 97%
rename from example/services/client/async-client-example.js
rename to example/services/client/async-client-example.cjs
index 6ded71e2..b1eb5d2e 100644
--- a/example/services/client/async-client-example.js
+++ b/example/services/client/async-client-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 
 async function main() {
   await rclnodejs.init();
diff --git a/example/services/client/async-client-example.mjs b/example/services/client/async-client-example.mjs
new file mode 100644
index 00000000..7508addf
--- /dev/null
+++ b/example/services/client/async-client-example.mjs
@@ -0,0 +1,65 @@
+// Copyright (c) 2026 RobotWebTools Contributors. All rights reserved.
+//
+// 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.
+
+// ESM variant of services/client/async-client-example.js.
+//
+// From an installed package you would write `import rclnodejs from 'rclnodejs'`;
+// run from this checkout we import the source entry point directly.
+
+import rclnodejs from '../../../index.js';
+
+await rclnodejs.init();
+
+const node = rclnodejs.createNode('async_client_example_node');
+const client = node.createClient(
+  'example_interfaces/srv/AddTwoInts',
+  'add_two_ints'
+);
+
+if (
+  rclnodejs.DistroUtils.getDistroId() >
+  rclnodejs.DistroUtils.getDistroId('humble')
+) {
+  // To view service events use the following command:
+  //    ros2 topic echo "/add_two_ints/_service_event"
+  client.configureIntrospection(
+    node.getClock(),
+    rclnodejs.QoS.profileSystemDefault,
+    rclnodejs.ServiceIntrospectionStates.METADATA
+  );
+}
+
+const request = {
+  a: BigInt(Math.floor(Math.random() * 100)),
+  b: BigInt(Math.floor(Math.random() * 100)),
+};
+
+const available = await client.waitForService(1000);
+if (!available) {
+  console.log('Error: service not available');
+  rclnodejs.shutdown();
+} else {
+  rclnodejs.spin(node);
+
+  console.log(`Sending: ${typeof request}`, request);
+
+  try {
+    const response = await client.sendRequestAsync(request, { timeout: 5000 });
+    console.log(`Result: ${typeof response}`, response);
+  } catch (error) {
+    console.log(`Error: ${error.message}`);
+  } finally {
+    rclnodejs.shutdown();
+  }
+}
diff --git a/example/services/client/client-example.js b/example/services/client/client-example.cjs
similarity index 96%
rename from example/services/client/client-example.js
rename to example/services/client/client-example.cjs
index ccd606e4..89e4eb1f 100644
--- a/example/services/client/client-example.js
+++ b/example/services/client/client-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 
 async function main() {
   await rclnodejs.init();
diff --git a/example/services/client/client-validation-example.js b/example/services/client/client-validation-example.cjs
similarity index 96%
rename from example/services/client/client-validation-example.js
rename to example/services/client/client-validation-example.cjs
index 3b6a45c9..2817a373 100644
--- a/example/services/client/client-validation-example.js
+++ b/example/services/client/client-validation-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 
 async function main() {
   await rclnodejs.init();
diff --git a/example/services/client/getmap-client-example.js b/example/services/client/getmap-client-example.cjs
similarity index 98%
rename from example/services/client/getmap-client-example.js
rename to example/services/client/getmap-client-example.cjs
index 55cfb926..a5381d30 100644
--- a/example/services/client/getmap-client-example.js
+++ b/example/services/client/getmap-client-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 
 async function main() {
   await rclnodejs.init();
diff --git a/example/services/service/getmap-service-example.js b/example/services/service/getmap-service-example.cjs
similarity index 98%
rename from example/services/service/getmap-service-example.js
rename to example/services/service/getmap-service-example.cjs
index 4e78411d..11994c1c 100644
--- a/example/services/service/getmap-service-example.js
+++ b/example/services/service/getmap-service-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 
 rclnodejs
   .init()
diff --git a/example/services/service/service-example.js b/example/services/service/service-example.cjs
similarity index 96%
rename from example/services/service/service-example.js
rename to example/services/service/service-example.cjs
index 9ac2c1b8..98b12133 100644
--- a/example/services/service/service-example.js
+++ b/example/services/service/service-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 
 rclnodejs
   .init()
diff --git a/example/services/service/service-example.mjs b/example/services/service/service-example.mjs
new file mode 100644
index 00000000..c7650ac7
--- /dev/null
+++ b/example/services/service/service-example.mjs
@@ -0,0 +1,52 @@
+// Copyright (c) 2026 RobotWebTools Contributors. All rights reserved.
+//
+// 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.
+
+// ESM variant of services/service/service-example.js.
+//
+// From an installed package you would write `import rclnodejs from 'rclnodejs'`;
+// run from this checkout we import the source entry point directly.
+
+import rclnodejs from '../../../index.js';
+
+await rclnodejs.init();
+
+const node = rclnodejs.createNode('service_example_node');
+
+const service = node.createService(
+  'example_interfaces/srv/AddTwoInts',
+  'add_two_ints',
+  (request, response) => {
+    console.log(`Incoming request: ${typeof request}`, request);
+    const result = response.template;
+    result.sum = request.a + request.b;
+    console.log(`Sending response: ${typeof result}`, result, '\n--');
+    response.send(result);
+  }
+);
+
+if (
+  rclnodejs.DistroUtils.getDistroId() >
+  rclnodejs.DistroUtils.getDistroId('humble')
+) {
+  console.log('Introspection configured');
+  // To view service events use the following command:
+  //    ros2 topic echo "/add_two_ints/_service_event"
+  service.configureIntrospection(
+    node.getClock(),
+    rclnodejs.QoS.profileSystemDefault,
+    rclnodejs.ServiceIntrospectionStates.CONTENTS
+  );
+}
+
+rclnodejs.spin(node);
diff --git a/example/timer/timer-example.js b/example/timer/timer-example.cjs
similarity index 90%
rename from example/timer/timer-example.js
rename to example/timer/timer-example.cjs
index da43c84d..5fbe27c5 100644
--- a/example/timer/timer-example.js
+++ b/example/timer/timer-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../index.js');
+const rclnodejs = require('../../index.js').default;
 
 rclnodejs
   .init()
@@ -22,7 +22,7 @@ rclnodejs
     let node = rclnodejs.createNode('timer_example_node');
 
     let timer = node.createTimer(BigInt(1000000000), () => {
-      console.log('One second escaped!');
+      console.log('One second elapsed!');
 
       console.log('Cancel this timer.');
       timer.cancel();
@@ -37,7 +37,7 @@ rclnodejs
         'The next call will be ' + timer.timeUntilNextCall() + 'ms later.'
       );
 
-      console.log('Shuting down...');
+      console.log('Shutting down...');
       rclnodejs.shutdown();
     });
 
diff --git a/example/timer/timer-example.mjs b/example/timer/timer-example.mjs
new file mode 100644
index 00000000..56d15bd8
--- /dev/null
+++ b/example/timer/timer-example.mjs
@@ -0,0 +1,46 @@
+// Copyright (c) 2026 RobotWebTools Contributors. All rights reserved.
+//
+// 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.
+
+// ESM variant of timer-example.js.
+//
+// From an installed package you would write `import rclnodejs from 'rclnodejs'`;
+// run from this checkout we import the source entry point directly.
+
+import rclnodejs from '../../index.js';
+
+await rclnodejs.init();
+
+const node = rclnodejs.createNode('timer_example_node');
+
+const timer = node.createTimer(BigInt(1000000000), () => {
+  console.log('One second elapsed!');
+
+  console.log('Cancel this timer.');
+  timer.cancel();
+
+  if (timer.isCanceled()) {
+    console.log('The timer has been canceled successfully.');
+  }
+
+  console.log('Reset the timer.');
+  timer.reset();
+  console.log(
+    'The next call will be ' + timer.timeUntilNextCall() + 'ms later.'
+  );
+
+  console.log('Shutting down...');
+  rclnodejs.shutdown();
+});
+
+rclnodejs.spin(node);
diff --git a/example/topics/README.md b/example/topics/README.md
index 0b147304..0832f2e1 100644
--- a/example/topics/README.md
+++ b/example/topics/README.md
@@ -10,66 +10,66 @@ ROS 2 topics are a fundamental communication pattern that allows nodes to exchan
 
 The `publisher/` directory contains examples of nodes that publish messages to topics:
 
-### 1. Basic Publisher (`publisher-example.js`)
+### 1. Basic Publisher (`publisher-example.cjs`)
 
 **Purpose**: Demonstrates basic string message publishing.
 
 - **Message Type**: `std_msgs/msg/String`
 - **Topic**: `topic`
 - **Functionality**: Publishes "Hello ROS" messages every second
-- **Run Command**: `node publisher/publisher-example.js`
+- **Run Command**: `node publisher/publisher-example.cjs`
 
-### 2. Content Filter Publisher (`publisher-content-filter-example.js`)
+### 2. Content Filter Publisher (`publisher-content-filter-example.cjs`)
 
 **Purpose**: Publishes temperature data for content filtering demonstrations.
 
 - **Message Type**: `sensor_msgs/msg/Temperature`
 - **Topic**: `temperature`
 - **Functionality**: Publishes random temperature values (0-100°C) every 100ms with header information
-- **Run Command**: `node publisher/publisher-content-filter-example.js`
-- **Pair**: Works with `subscription-content-filter-example.js`
+- **Run Command**: `node publisher/publisher-content-filter-example.cjs`
+- **Pair**: Works with `subscription-content-filter-example.cjs`
 
-### 3. Message Publisher (`publisher-message-example.js`)
+### 3. Message Publisher (`publisher-message-example.cjs`)
 
 **Purpose**: Demonstrates publishing complex structured messages.
 
 - **Message Type**: `sensor_msgs/msg/JointState`
 - **Topic**: `JointState`
 - **Functionality**: Publishes joint state information with header, names, positions, velocities, and efforts
-- **Run Command**: `node publisher/publisher-message-example.js`
-- **Pair**: Works with `subscription-message-example.js`
+- **Run Command**: `node publisher/publisher-message-example.cjs`
+- **Pair**: Works with `subscription-message-example.cjs`
 
-### 4. MultiArray Publisher (`publisher-multiarray-example.js`)
+### 4. MultiArray Publisher (`publisher-multiarray-example.cjs`)
 
 **Purpose**: Shows how to publish multi-dimensional array data.
 
 - **Message Type**: `std_msgs/msg/Int32MultiArray`
 - **Topic**: `Int32MultiArray`
 - **Functionality**: Publishes 3D array data (2×3×3) with proper layout information
-- **Run Command**: `node publisher/publisher-multiarray-example.js`
-- **Pair**: Works with `subscription-multiarray-example.js`
+- **Run Command**: `node publisher/publisher-multiarray-example.cjs`
+- **Pair**: Works with `subscription-multiarray-example.cjs`
 
-### 5. QoS Publisher (`publisher-qos-example.js`)
+### 5. QoS Publisher (`publisher-qos-example.cjs`)
 
 **Purpose**: Demonstrates Quality of Service (QoS) configuration for publishers.
 
 - **Message Type**: `std_msgs/msg/String`
 - **Topic**: `topic`
 - **Functionality**: Publishes messages with custom QoS settings (system default policies)
-- **Run Command**: `node publisher/publisher-qos-example.js`
-- **Pair**: Works with `subscription-qos-example.js`
+- **Run Command**: `node publisher/publisher-qos-example.cjs`
+- **Pair**: Works with `subscription-qos-example.cjs`
 
-### 6. Raw Message Publisher (`publisher-raw-message.js`)
+### 6. Raw Message Publisher (`publisher-raw-message.cjs`)
 
 **Purpose**: Shows how to publish raw binary data.
 
 - **Message Type**: `test_msgs/msg/BasicTypes`
 - **Topic**: `chatter`
 - **Functionality**: Publishes raw Buffer data ("Hello ROS World")
-- **Run Command**: `node publisher/publisher-raw-message.js`
-- **Pair**: Works with `subscription-raw-message.js`
+- **Run Command**: `node publisher/publisher-raw-message.cjs`
+- **Pair**: Works with `subscription-raw-message.cjs`
 
-### 7. Publisher Validation (`publisher-validation-example.js`)
+### 7. Publisher Validation (`publisher-validation-example.cjs`)
 
 **Purpose**: Demonstrates message validation features for publishers.
 
@@ -87,24 +87,24 @@ The `publisher/` directory contains examples of nodes that publish messages to t
   - Catch invalid messages before publishing
   - Dynamic validation toggle with `willValidateMessage` property
   - Detailed error reports with field-level issues
-- **Run Command**: `node publisher/publisher-validation-example.js`
+- **Run Command**: `node publisher/publisher-validation-example.cjs`
 - **Note**: Standalone example - no subscriber required
 
 ## Subscriber Examples
 
 The `subscriber/` directory contains examples of nodes that subscribe to topics:
 
-### 1. Basic Subscriber (`subscription-example.js`)
+### 1. Basic Subscriber (`subscription-example.cjs`)
 
 **Purpose**: Demonstrates basic message subscription.
 
 - **Message Type**: `std_msgs/msg/String`
 - **Topic**: `topic`
 - **Functionality**: Receives and logs string messages
-- **Run Command**: `node subscriber/subscription-example.js`
-- **Pair**: Works with `publisher-example.js`
+- **Run Command**: `node subscriber/subscription-example.cjs`
+- **Pair**: Works with `publisher-example.cjs`
 
-### 2. Content Filter Subscriber (`subscription-content-filter-example.js`)
+### 2. Content Filter Subscriber (`subscription-content-filter-example.cjs`)
 
 **Purpose**: Demonstrates content filtering to receive only relevant messages.
 
@@ -112,20 +112,20 @@ The `subscriber/` directory contains examples of nodes that subscribe to topics:
 - **Topic**: `temperature`
 - **Functionality**: Only receives temperature messages above 50°C using content filters
 - **Features**: ROS 2 Humble+ content filtering with expression `temperature > %0`
-- **Run Command**: `node subscriber/subscription-content-filter-example.js`
-- **Pair**: Works with `publisher-content-filter-example.js`
+- **Run Command**: `node subscriber/subscription-content-filter-example.cjs`
+- **Pair**: Works with `publisher-content-filter-example.cjs`
 
-### 3. Message Subscriber (`subscription-message-example.js`)
+### 3. Message Subscriber (`subscription-message-example.cjs`)
 
 **Purpose**: Receives complex structured messages.
 
 - **Message Type**: `sensor_msgs/msg/JointState`
 - **Topic**: `JointState`
 - **Functionality**: Receives and logs joint state information
-- **Run Command**: `node subscriber/subscription-message-example.js`
-- **Pair**: Works with `publisher-message-example.js`
+- **Run Command**: `node subscriber/subscription-message-example.cjs`
+- **Pair**: Works with `publisher-message-example.cjs`
 
-### 4. MultiArray Subscriber (`subscription-multiarray-example.js`)
+### 4. MultiArray Subscriber (`subscription-multiarray-example.cjs`)
 
 **Purpose**: Demonstrates receiving and parsing multi-dimensional arrays.
 
@@ -133,20 +133,20 @@ The `subscriber/` directory contains examples of nodes that subscribe to topics:
 - **Topic**: `Int32MultiArray`
 - **Functionality**: Receives 3D arrays and iterates through all elements with proper indexing
 - **Features**: Shows how to parse layout information and access array elements
-- **Run Command**: `node subscriber/subscription-multiarray-example.js`
-- **Pair**: Works with `publisher-multiarray-example.js`
+- **Run Command**: `node subscriber/subscription-multiarray-example.cjs`
+- **Pair**: Works with `publisher-multiarray-example.cjs`
 
-### 5. QoS Subscriber (`subscription-qos-example.js`)
+### 5. QoS Subscriber (`subscription-qos-example.cjs`)
 
 **Purpose**: Demonstrates QoS configuration for subscribers.
 
 - **Message Type**: `std_msgs/msg/String`
 - **Topic**: `topic`
 - **Functionality**: Receives messages with system default QoS profile
-- **Run Command**: `node subscriber/subscription-qos-example.js`
-- **Pair**: Works with `publisher-qos-example.js`
+- **Run Command**: `node subscriber/subscription-qos-example.cjs`
+- **Pair**: Works with `publisher-qos-example.cjs`
 
-### 6. Raw Message Subscriber (`subscription-raw-message.js`)
+### 6. Raw Message Subscriber (`subscription-raw-message.cjs`)
 
 **Purpose**: Shows how to receive raw binary data.
 
@@ -154,10 +154,10 @@ The `subscriber/` directory contains examples of nodes that subscribe to topics:
 - **Topic**: `chatter`
 - **Functionality**: Receives raw Buffer data and converts to UTF-8 string
 - **Features**: Uses `{ isRaw: true }` option
-- **Run Command**: `node subscriber/subscription-raw-message.js`
-- **Pair**: Works with `publisher-raw-message.js`
+- **Run Command**: `node subscriber/subscription-raw-message.cjs`
+- **Pair**: Works with `publisher-raw-message.cjs`
 
-### 7. Service Event Subscriber (`subscription-service-event-example.js`)
+### 7. Service Event Subscriber (`subscription-service-event-example.cjs`)
 
 **Purpose**: Demonstrates subscribing to service events.
 
@@ -165,9 +165,9 @@ The `subscriber/` directory contains examples of nodes that subscribe to topics:
 - **Topic**: `/add_two_ints/_service_event`
 - **Functionality**: Monitors service call events for the AddTwoInts service
 - **Features**: ROS 2 service introspection capabilities
-- **Run Command**: `node subscriber/subscription-service-event-example.js`
+- **Run Command**: `node subscriber/subscription-service-event-example.cjs`
 
-### 8. Serialization Modes Subscriber (`subscription-serialization-modes-example.js`)
+### 8. Serialization Modes Subscriber (`subscription-serialization-modes-example.cjs`)
 
 **Purpose**: Demonstrates different serialization modes for message handling.
 
@@ -175,9 +175,9 @@ The `subscriber/` directory contains examples of nodes that subscribe to topics:
 - **Topic**: `scan`
 - **Functionality**: Shows how 'default', 'plain', and 'json' modes affect message serialization
 - **Features**: Message serialization control for web applications and JSON compatibility
-- **Run Command**: `node subscriber/subscription-serialization-modes-example.js`
+- **Run Command**: `node subscriber/subscription-serialization-modes-example.cjs`
 
-### 9. JSON Utilities Subscriber (`subscription-json-utilities-example.js`)
+### 9. JSON Utilities Subscriber (`subscription-json-utilities-example.cjs`)
 
 **Purpose**: Demonstrates manual message conversion utilities.
 
@@ -185,9 +185,9 @@ The `subscriber/` directory contains examples of nodes that subscribe to topics:
 - **Topic**: `scan`
 - **Functionality**: Shows how to use toJSONSafe and toJSONString utilities for manual conversion
 - **Features**: Manual conversion of TypedArrays, BigInt, and special values for JSON serialization
-- **Run Command**: `node subscriber/subscription-json-utilities-example.js`
+- **Run Command**: `node subscriber/subscription-json-utilities-example.cjs`
 
-### 10. Observable Subscriber (`subscription-observable-example.js`)
+### 10. Observable Subscriber (`subscription-observable-example.cjs`)
 
 **Purpose**: Demonstrates RxJS Observable subscriptions for reactive programming.
 
@@ -199,20 +199,20 @@ The `subscriber/` directory contains examples of nodes that subscribe to topics:
   - Message transformation with `map()`
   - Content filtering with `filter()`
   - Batching with `bufferCount()`
-- **Run Command**: `node subscriber/subscription-observable-example.js`
-- **Pair**: Works with `publisher-example.js`
+- **Run Command**: `node subscriber/subscription-observable-example.cjs`
+- **Pair**: Works with `publisher-example.cjs`
 
 ## Validator Example
 
 The `validator/` directory contains validation utilities:
 
-### Validator (`validator-example.js`)
+### Validator (`validator-example.cjs`)
 
 **Purpose**: Demonstrates ROS 2 name validation functions.
 
 - **Functionality**: Validates topic names, node names, namespaces, and full topic names
 - **Features**: Uses rclnodejs validator utilities
-- **Run Command**: `node validator/validator-example.js`
+- **Run Command**: `node validator/validator-example.cjs`
 
 ## Paired Examples
 
@@ -220,13 +220,13 @@ Several examples work together to demonstrate complete communication:
 
 | Publisher                             | Subscriber                               | Description                     |
 | ------------------------------------- | ---------------------------------------- | ------------------------------- |
-| `publisher-example.js`                | `subscription-example.js`                | Basic string messaging          |
-| `publisher-content-filter-example.js` | `subscription-content-filter-example.js` | Temperature data with filtering |
-| `publisher-message-example.js`        | `subscription-message-example.js`        | Complex structured messages     |
-| `publisher-multiarray-example.js`     | `subscription-multiarray-example.js`     | Multi-dimensional array data    |
-| `publisher-qos-example.js`            | `subscription-qos-example.js`            | QoS configuration               |
-| `publisher-raw-message.js`            | `subscription-raw-message.js`            | Raw binary data                 |
-| `publisher-example.js`                | `subscription-observable-example.js`     | RxJS Observable subscription    |
+| `publisher-example.cjs`                | `subscription-example.cjs`                | Basic string messaging          |
+| `publisher-content-filter-example.cjs` | `subscription-content-filter-example.cjs` | Temperature data with filtering |
+| `publisher-message-example.cjs`        | `subscription-message-example.cjs`        | Complex structured messages     |
+| `publisher-multiarray-example.cjs`     | `subscription-multiarray-example.cjs`     | Multi-dimensional array data    |
+| `publisher-qos-example.cjs`            | `subscription-qos-example.cjs`            | QoS configuration               |
+| `publisher-raw-message.cjs`            | `subscription-raw-message.cjs`            | Raw binary data                 |
+| `publisher-example.cjs`                | `subscription-observable-example.cjs`     | RxJS Observable subscription    |
 
 ## How to Run Examples
 
@@ -234,11 +234,11 @@ Several examples work together to demonstrate complete communication:
 2. **Navigate**: Change to the example/topics directory
 3. **Run Publisher**: Start the publisher in one terminal
    ```bash
-   node publisher/publisher-example.js
+   node publisher/publisher-example.cjs
    ```
 4. **Run Subscriber**: Start the corresponding subscriber in another terminal
    ```bash
-   node subscriber/subscription-example.js
+   node subscriber/subscription-example.cjs
    ```
 
 ## Key Concepts Demonstrated
diff --git a/example/topics/publisher/publisher-content-filter-example.js b/example/topics/publisher/publisher-content-filter-example.cjs
similarity index 95%
rename from example/topics/publisher/publisher-content-filter-example.js
rename to example/topics/publisher/publisher-content-filter-example.cjs
index d759189a..0866aa35 100644
--- a/example/topics/publisher/publisher-content-filter-example.js
+++ b/example/topics/publisher/publisher-content-filter-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 
 async function main() {
   await rclnodejs.init();
diff --git a/example/topics/publisher/publisher-example.js b/example/topics/publisher/publisher-example.cjs
similarity index 94%
rename from example/topics/publisher/publisher-example.js
rename to example/topics/publisher/publisher-example.cjs
index 0d7f3535..e6b1e252 100644
--- a/example/topics/publisher/publisher-example.js
+++ b/example/topics/publisher/publisher-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 
 rclnodejs.init().then(() => {
   const node = rclnodejs.createNode('publisher_example_node');
diff --git a/example/topics/publisher/publisher-example.mjs b/example/topics/publisher/publisher-example.mjs
new file mode 100644
index 00000000..d492cf87
--- /dev/null
+++ b/example/topics/publisher/publisher-example.mjs
@@ -0,0 +1,34 @@
+// Copyright (c) 2026 RobotWebTools Contributors. All rights reserved.
+//
+// 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.
+
+// ESM variant of publisher-example.js.
+//
+// From an installed package you would write `import rclnodejs from 'rclnodejs'`;
+// run from this checkout we import the source entry point directly. Note the
+// top-level `await` — an ES module feature that removes the `.then()` nesting.
+
+import rclnodejs from '../../../index.js';
+
+await rclnodejs.init();
+
+const node = rclnodejs.createNode('publisher_example_node');
+const publisher = node.createPublisher('std_msgs/msg/String', 'topic');
+
+let counter = 0;
+setInterval(() => {
+  console.log(`Publishing message: Hello ROS ${counter}`);
+  publisher.publish(`Hello ROS ${counter++}`);
+}, 1000);
+
+rclnodejs.spin(node);
diff --git a/example/topics/publisher/publisher-message-example.js b/example/topics/publisher/publisher-message-example.cjs
similarity index 95%
rename from example/topics/publisher/publisher-message-example.js
rename to example/topics/publisher/publisher-message-example.cjs
index 8036b237..5d497c5f 100644
--- a/example/topics/publisher/publisher-message-example.js
+++ b/example/topics/publisher/publisher-message-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 
 rclnodejs
   .init()
diff --git a/example/topics/publisher/publisher-multiarray-example.js b/example/topics/publisher/publisher-multiarray-example.cjs
similarity index 96%
rename from example/topics/publisher/publisher-multiarray-example.js
rename to example/topics/publisher/publisher-multiarray-example.cjs
index b1d4f100..cb1abf10 100644
--- a/example/topics/publisher/publisher-multiarray-example.js
+++ b/example/topics/publisher/publisher-multiarray-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 
 rclnodejs
   .init()
diff --git a/example/topics/publisher/publisher-qos-example.js b/example/topics/publisher/publisher-qos-example.cjs
similarity index 96%
rename from example/topics/publisher/publisher-qos-example.js
rename to example/topics/publisher/publisher-qos-example.cjs
index 481dd370..72d3a915 100644
--- a/example/topics/publisher/publisher-qos-example.js
+++ b/example/topics/publisher/publisher-qos-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 const { QoS } = rclnodejs;
 
 rclnodejs.init().then(() => {
diff --git a/example/topics/publisher/publisher-raw-message.js b/example/topics/publisher/publisher-raw-message.cjs
similarity index 95%
rename from example/topics/publisher/publisher-raw-message.js
rename to example/topics/publisher/publisher-raw-message.cjs
index aac8df9d..b4c93126 100644
--- a/example/topics/publisher/publisher-raw-message.js
+++ b/example/topics/publisher/publisher-raw-message.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 
 rclnodejs
   .init()
diff --git a/example/topics/publisher/publisher-validation-example.js b/example/topics/publisher/publisher-validation-example.cjs
similarity index 95%
rename from example/topics/publisher/publisher-validation-example.js
rename to example/topics/publisher/publisher-validation-example.cjs
index 41265a6e..c741c73b 100644
--- a/example/topics/publisher/publisher-validation-example.js
+++ b/example/topics/publisher/publisher-validation-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 
 rclnodejs.init().then(() => {
   const node = rclnodejs.createNode('publisher_validation_example_node');
diff --git a/example/topics/subscriber/subscription-content-filter-example.js b/example/topics/subscriber/subscription-content-filter-example.cjs
similarity index 98%
rename from example/topics/subscriber/subscription-content-filter-example.js
rename to example/topics/subscriber/subscription-content-filter-example.cjs
index 24250f85..1802c59c 100644
--- a/example/topics/subscriber/subscription-content-filter-example.js
+++ b/example/topics/subscriber/subscription-content-filter-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 
 /**
  * This example demonstrates the use of content-filtering
diff --git a/example/topics/subscriber/subscription-example.js b/example/topics/subscriber/subscription-example.cjs
similarity index 94%
rename from example/topics/subscriber/subscription-example.js
rename to example/topics/subscriber/subscription-example.cjs
index 2785b392..02d55e1e 100644
--- a/example/topics/subscriber/subscription-example.js
+++ b/example/topics/subscriber/subscription-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 
 rclnodejs.init().then(() => {
   const node = rclnodejs.createNode('subscription_example_node');
diff --git a/example/topics/subscriber/subscription-example.mjs b/example/topics/subscriber/subscription-example.mjs
new file mode 100644
index 00000000..ac0783fc
--- /dev/null
+++ b/example/topics/subscriber/subscription-example.mjs
@@ -0,0 +1,30 @@
+// Copyright (c) 2026 RobotWebTools Contributors. All rights reserved.
+//
+// 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.
+
+// ESM variant of subscription-example.js.
+//
+// From an installed package you would write `import rclnodejs from 'rclnodejs'`;
+// run from this checkout we import the source entry point directly.
+
+import rclnodejs from '../../../index.js';
+
+await rclnodejs.init();
+
+const node = rclnodejs.createNode('subscription_example_node');
+
+node.createSubscription('std_msgs/msg/String', 'topic', (msg) => {
+  console.log(`Received message: ${typeof msg}`, msg);
+});
+
+rclnodejs.spin(node);
diff --git a/example/topics/subscriber/subscription-json-utilities-example.js b/example/topics/subscriber/subscription-json-utilities-example.cjs
similarity index 96%
rename from example/topics/subscriber/subscription-json-utilities-example.js
rename to example/topics/subscriber/subscription-json-utilities-example.cjs
index 4efad05f..06fc2986 100644
--- a/example/topics/subscriber/subscription-json-utilities-example.js
+++ b/example/topics/subscriber/subscription-json-utilities-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 
 /**
  * This example demonstrates the JSON utility functions for manual message conversion.
diff --git a/example/topics/subscriber/subscription-message-example.js b/example/topics/subscriber/subscription-message-example.cjs
similarity index 94%
rename from example/topics/subscriber/subscription-message-example.js
rename to example/topics/subscriber/subscription-message-example.cjs
index aaf62e19..e11096ac 100644
--- a/example/topics/subscriber/subscription-message-example.js
+++ b/example/topics/subscriber/subscription-message-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 
 rclnodejs
   .init()
diff --git a/example/topics/subscriber/subscription-multiarray-example.js b/example/topics/subscriber/subscription-multiarray-example.cjs
similarity index 97%
rename from example/topics/subscriber/subscription-multiarray-example.js
rename to example/topics/subscriber/subscription-multiarray-example.cjs
index ceefb7b5..ffe8d350 100644
--- a/example/topics/subscriber/subscription-multiarray-example.js
+++ b/example/topics/subscriber/subscription-multiarray-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 
 rclnodejs
   .init()
diff --git a/example/topics/subscriber/subscription-observable-example.js b/example/topics/subscriber/subscription-observable-example.cjs
similarity index 97%
rename from example/topics/subscriber/subscription-observable-example.js
rename to example/topics/subscriber/subscription-observable-example.cjs
index 3dccac3e..a3f8bf56 100644
--- a/example/topics/subscriber/subscription-observable-example.js
+++ b/example/topics/subscriber/subscription-observable-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 const { throttleTime, map, filter, bufferCount } = require('rxjs');
 
 async function main() {
diff --git a/example/topics/subscriber/subscription-qos-example.js b/example/topics/subscriber/subscription-qos-example.cjs
similarity index 94%
rename from example/topics/subscriber/subscription-qos-example.js
rename to example/topics/subscriber/subscription-qos-example.cjs
index dee83715..f479be7f 100644
--- a/example/topics/subscriber/subscription-qos-example.js
+++ b/example/topics/subscriber/subscription-qos-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 const { QoS } = rclnodejs;
 
 rclnodejs.init().then(() => {
diff --git a/example/topics/subscriber/subscription-raw-message.js b/example/topics/subscriber/subscription-raw-message.cjs
similarity index 94%
rename from example/topics/subscriber/subscription-raw-message.js
rename to example/topics/subscriber/subscription-raw-message.cjs
index 711c0de4..7e753649 100644
--- a/example/topics/subscriber/subscription-raw-message.js
+++ b/example/topics/subscriber/subscription-raw-message.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 
 rclnodejs.init().then(() => {
   const node = rclnodejs.createNode('subscription_message_example_node');
diff --git a/example/topics/subscriber/subscription-serialization-modes-example.js b/example/topics/subscriber/subscription-serialization-modes-example.cjs
similarity index 97%
rename from example/topics/subscriber/subscription-serialization-modes-example.js
rename to example/topics/subscriber/subscription-serialization-modes-example.cjs
index 6bfe5dc6..ba622598 100644
--- a/example/topics/subscriber/subscription-serialization-modes-example.js
+++ b/example/topics/subscriber/subscription-serialization-modes-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 
 /**
  * This example demonstrates the use of serialization modes for subscriptions.
diff --git a/example/topics/subscriber/subscription-service-event-example.js b/example/topics/subscriber/subscription-service-event-example.cjs
similarity index 94%
rename from example/topics/subscriber/subscription-service-event-example.js
rename to example/topics/subscriber/subscription-service-event-example.cjs
index 91757fb4..b52832fec 100644
--- a/example/topics/subscriber/subscription-service-event-example.js
+++ b/example/topics/subscriber/subscription-service-event-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 
 async function main() {
   await rclnodejs.init();
diff --git a/example/topics/validator/validator-example.js b/example/topics/validator/validator-example.cjs
similarity index 95%
rename from example/topics/validator/validator-example.js
rename to example/topics/validator/validator-example.cjs
index 06b97a45..da25479f 100644
--- a/example/topics/validator/validator-example.js
+++ b/example/topics/validator/validator-example.cjs
@@ -14,7 +14,7 @@
 
 'use strict';
 
-const rclnodejs = require('../../../index.js');
+const rclnodejs = require('../../../index.js').default;
 const { validator } = rclnodejs;
 
 console.log(
diff --git a/package.json b/package.json
index 6cbaf45a..ad5b8615 100644
--- a/package.json
+++ b/package.json
@@ -3,22 +3,33 @@
   "version": "2.0.0",
   "description": "ROS2.0 JavaScript client with Node.js",
   "type": "module",
-  "main": "index.js",
+  "main": "./dist/index.cjs",
+  "module": "./dist/index.js",
   "types": "types/index.d.ts",
   "exports": {
     ".": {
       "types": "./types/index.d.ts",
-      "default": "./index.js"
+      "import": "./dist/index.js",
+      "require": "./dist/index.cjs",
+      "default": "./dist/index.js"
     },
     "./web": {
       "types": "./web/index.d.ts",
-      "default": "./web/index.js"
+      "import": "./dist/web.js",
+      "require": "./dist/web.cjs",
+      "default": "./dist/web.js"
     },
     "./web/server": {
       "types": "./lib/runtime/index.d.ts",
-      "default": "./lib/runtime/index.js"
+      "import": "./dist/server.js",
+      "require": "./dist/server.cjs",
+      "default": "./dist/server.js"
+    },
+    "./rosocket": {
+      "import": "./dist/rosocket.js",
+      "require": "./dist/rosocket.cjs",
+      "default": "./dist/rosocket.js"
     },
-    "./rosocket": "./rosocket/index.js",
     "./lib/*": "./lib/*.js",
     "./lib/*.js": "./lib/*.js",
     "./package.json": "./package.json"
@@ -34,6 +45,7 @@
   "scripts": {
     "build": "node-gyp -j 16 build",
     "build:dev": "node-gyp -j 16 build --debug",
+    "build:dist": "tsup",
     "rebuild": "npm run clean && node-gyp -j 16 rebuild",
     "rebuild:dev": "npm run clean && node-gyp -j 16 rebuild --debug",
     "generate-messages": "node scripts/generate_messages.cjs",
@@ -51,7 +63,8 @@
     "test-idl": "node --expose-gc ./scripts/run_test.cjs --idl",
     "lint": "eslint && node ./scripts/cpplint.cjs",
     "test:asan": "bash scripts/run_asan_test.sh",
-    "format": "clang-format -i -style=file ./src/*.cpp ./src/*.h && npx --yes prettier --write \"{lib,rosidl_gen,rostsd_gen,rosidl_parser,types,example,test,scripts,benchmark,rostsd_gen}/**/*.{js,cjs,md,ts}\" ./*.{js,md,ts}",
+    "format": "clang-format -i -style=file ./src/*.cpp ./src/*.h && npx --yes prettier --write \"{lib,rosidl_gen,rostsd_gen,rosidl_parser,types,example,test,scripts,benchmark,rostsd_gen}/**/*.{js,cjs,mjs,md,ts}\" ./*.{js,md,ts}",
+    "prepack": "npm run build:dist",
     "prepare": "husky",
     "coverage": "cat ./coverage/lcov.info | ./node_modules/coveralls/bin/coveralls.js",
     "prebuild:node": "prebuildify --napi --strip --name node --target 20.20.2",
@@ -99,6 +112,7 @@
     "sinon": "^22.0.0",
     "tree-kill": "^1.2.2",
     "tsd": "^0.33.0",
+    "tsup": "^8.5.1",
     "typescript": "^6.0.2"
   },
   "dependencies": {
diff --git a/scripts/npm-pack.sh b/scripts/npm-pack.sh
index ae924897..7ce5314b 100755
--- a/scripts/npm-pack.sh
+++ b/scripts/npm-pack.sh
@@ -31,8 +31,11 @@ FILENAME=`npm pack --ignore-scripts $RAWMODULEDIR | awk '{for(i=1; i<=NF; i++) i
 TARFILENAME="$WORKDIR/$FILENAME"
 
 popd > /dev/null
-mkdir -p dist
-cp -f $TARFILENAME ./dist/
+# Output the packed tarball to ./pack (NOT ./dist): since the ESM/CJS dual build
+# (tsup) now owns ./dist and that directory is published to npm, dropping the
+# tarball there would ship pack artifacts inside the package.
+mkdir -p pack
+cp -f $TARFILENAME ./pack/
 rm -rf $WORKDIR
 
-echo "Generated ./dist/$FILENAME"
+echo "Generated ./pack/$FILENAME"
diff --git a/tsup.config.js b/tsup.config.js
new file mode 100644
index 00000000..264c79ee
--- /dev/null
+++ b/tsup.config.js
@@ -0,0 +1,91 @@
+// Copyright (c) 2026 RobotWebTools Contributors. All rights reserved.
+//
+// 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.
+
+// tsup configuration for the dual ESM + CommonJS build.
+//
+// The authored source is native ESM (package.json "type": "module"). External
+// consumers that use `require('rclnodejs')` still need a CommonJS build, so
+// tsup emits both formats into a FLAT dist/ (depth-1) layout:
+//
+//   dist/index.js   dist/index.cjs    (exports ".")
+//   dist/web.js     dist/web.cjs      (exports "./web")
+//   dist/server.js  dist/server.cjs   (exports "./web/server")
+//   dist/rosocket.js dist/rosocket.cjs (exports "./rosocket")
+//
+// The flat depth-1 layout is deliberate: the native loader resolves the
+// prebuilt binaries and the `.node` addon via `path.join(__dirname, '..', ...)`
+// and `bindings()` walking up to package.json. With every bundle one level
+// under the package root, those `..`-relative paths stay correct.
+
+import path from 'path';
+import { fileURLToPath } from 'url';
+import { defineConfig } from 'tsup';
+
+const ROOT = path.dirname(fileURLToPath(import.meta.url));
+const DIST = path.join(ROOT, 'dist');
+
+// The generator/parser trees (rosidl_gen/*, rostsd_gen/*) are CommonJS islands
+// that resolve their own template and `generated/` paths from their real
+// on-disk location. They must NOT be bundled. esbuild would otherwise inline
+// them and break `__dirname`-relative template lookups. Keep them external and
+// rewrite each specifier to a path that is correct relative to the flat dist/
+// output (e.g. `./rosidl_gen/index.cjs` -> `../rosidl_gen/index.cjs`).
+const externalizeIslands = {
+  name: 'externalize-cjs-islands',
+  setup(build) {
+    build.onResolve({ filter: /[\\/](rosidl_gen|rostsd_gen)[\\/]/ }, (args) => {
+      const abs = path.resolve(args.resolveDir, args.path);
+      let rel = path.relative(DIST, abs).split(path.sep).join('/');
+      if (!rel.startsWith('.')) {
+        rel = './' + rel;
+      }
+      return { path: rel, external: true };
+    });
+  },
+};
+
+export default defineConfig({
+  entry: {
+    index: 'index.js',
+    web: 'web/index.js',
+    server: 'lib/runtime/index.js',
+    rosocket: 'rosocket/index.js',
+  },
+  outDir: 'dist',
+  format: ['esm', 'cjs'],
+  platform: 'node',
+  target: 'node20',
+  // One self-contained file per entry/format keeps the dist/ layout flat and
+  // the externalized island paths consistent.
+  splitting: false,
+  sourcemap: true,
+  clean: true,
+  // Type declarations are handled separately; do not emit here.
+  dts: false,
+  // Provide import.meta.url in the CJS output (and __dirname in ESM) so the
+  // native loader's path resolution works in both formats.
+  shims: true,
+  esbuildPlugins: [externalizeIslands],
+  esbuildOptions(options, context) {
+    // Hoist a lone `export default` to `module.exports` in the CJS output so
+    // that `const rclnodejs = require('rclnodejs')` keeps working with no
+    // `.default` indirection. Only collapses when `default` is the sole export
+    // (the root entry); named-only entries such as ./web are left untouched.
+    if (context.format === 'cjs') {
+      options.footer = {
+        js: 'if (module.exports && module.exports.default !== void 0 && Object.keys(module.exports).every(function (k) { return k === "default" || k === "__esModule"; })) { module.exports = module.exports.default; }',
+      };
+    }
+  },
+});
diff --git a/web/client.js b/web/client.js
index c6d756bf..3aac6cb8 100644
--- a/web/client.js
+++ b/web/client.js
@@ -29,13 +29,23 @@
 //   - { http, ws }         → explicit endpoint pair.
 
 let WS = globalThis.WebSocket;
-if (!WS) {
+let _wsResolved = !!WS;
+
+// Resolve a Node WebSocket implementation lazily. This avoids a top-level
+// `await import('ws')`, which is unavailable in the CommonJS build. In browsers
+// `globalThis.WebSocket` is used and the `ws` package is never touched.
+async function _ensureWS() {
+  if (_wsResolved) {
+    return WS;
+  }
+  _wsResolved = true;
   try {
     const wsModule = await import('ws');
     WS = wsModule.WebSocket || wsModule.default;
   } catch {
     // No WebSocket implementation available in this environment.
   }
+  return WS;
 }
 
 // Frame ids are UUIDs so they never collide across sessions or modules
@@ -71,7 +81,8 @@ class _WsLink {
     this._closed = false;
   }
 
-  connect() {
+  async connect() {
+    await _ensureWS();
     return new Promise((resolve, reject) => {
       if (!WS) {
         return reject(