diff --git a/package.json b/package.json
index 320c1e6..6da113b 100644
--- a/package.json
+++ b/package.json
@@ -24,7 +24,7 @@
 	"__scripts:comment:bundle2": "todo: could improve it by deleting everything except _snowpack - something like rm -rfvi !('build/_snowpack'). be careful not to delete anything above build/",
 	"scripts": {
 		"bundle": "npm run build && rm -f build/index.js",
-		"watch": "snowpack build --watch --hmr",
+		"watch": "snowpack dev",
 		"build": "snowpack build"
 	}
 }
diff --git a/plugin.php b/plugin.php
index 4a25c7f..045b003 100644
--- a/plugin.php
+++ b/plugin.php
@@ -83,6 +83,22 @@ function get_serve_folder() {
 	return $folder;
 }
 
+// Note: This is only necessary to demonstrate different approaches. In real-world applications you'd either
+// commit to running the watch task or not, or at least the application code wouldn't care which.
+function running_watch_task() {
+	static $running = null; // Cache the result so it's not run more than once per page load.
+
+	if ( null === $running ) {
+		$null    = null;
+		$running = is_resource( @fsockopen( 'localhost', '8081', $null, $null, 1 ) );
+
+		if ( ! $running ) {
+			error_clear_last(); // Prevent the `body.php-error` CSS class from being added.
+		}
+	}
+
+	return $running;
+}
 
 // register/enqueue scripts & styles
 add_action( 'admin_enqueue_scripts', function( $hook_suffix ) {
@@ -95,6 +111,13 @@ function get_serve_folder() {
 	// need to add wp-polyfill as a dependency? maybe for api-fetch & other stuff
 		// it's added automatically?
 
+	if ( running_watch_task() ) {
+		$script_url = 'http://localhost:8081/index.js';
+		// make url/port DRY w/ websocket below
+	} else {
+		$script_url = plugins_url( "$folder/index.js", __FILE__ );
+	}
+
 	if ( 'source' === $folder ) {
 		// Don't need HTM in production, because Babel transpiles it away.
 		$dependencies[] = 'htm';
@@ -106,7 +129,8 @@ function get_serve_folder() {
 
 	wp_enqueue_script(
 		'no-build-tools-no-problems',
-		plugins_url( "$folder/index.js", __FILE__ ),
+		$script_url,
+		/// rename to more specific
 		$dependencies,
 		filemtime( __DIR__ . "/$folder/index.js" ),
 
@@ -164,27 +188,19 @@ function get_serve_folder() {
 	<?php
 } );
 
-// setup auto reloading
-// actual hmr isn't working yet -- https://github.com/snowpackjs/snowpack/discussions/2565
+// configure hot module reloading
 // should be in core.php?
 add_action( 'admin_print_scripts-toplevel_page_no-build-tools-no-problems', function() {
-	$hmr_folder = '/build/vendor/';
-
-	if ( ! file_exists( __DIR__ . $hmr_folder . '/hmr-client.js' ) ) {
-		// return early if not running watch task, how to detect?
-		// presence of hmr-client in vendor folder? no b/c bundle task doesn't delete it
+	if ( ! running_watch_task() ) {
 		return;
 	}
 
 	?>
 
 	<script>
-		// is it safe to hardcode that port? maybe set it in config file and pull from .env file?
-		window.HMR_WEBSOCKET_URL = 'ws://localhost:12321';
+		// not safe to hardcode the port. maybe set it in config file and pull from .env file?
+		window.HMR_WEBSOCKET_URL = 'ws://localhost:8081';
 	</script>
 
-    <script type="module" src="<?php echo plugins_url( $hmr_folder . '/hmr-client.js', __FILE__ ); ?>"></script>
-	<script type="module" src="<?php echo plugins_url( $hmr_folder . '/hmr-error-overlay.js', __FILE__ ); ?>"></script>
-
 	<?php
 } );
diff --git a/readme.md b/readme.md
index 5239d11..83eba42 100644
--- a/readme.md
+++ b/readme.md
@@ -23,7 +23,7 @@ You can run the same `source/` scripts in production if you'd like. For smaller
 
 If that's where you're at, you can `rm .gitignore babel.config.js package.json package-lock.json`, and revel in how tidy your root folder is.
 
-If want to optimize performance, or need to support older browsers, then you can add a build step for production files. You'll still be able to develop locally without any `watch` tooling, though.
+If want to optimize performance, or need to support older browsers, then you can use the <code>build</code> step for your production files. You'll still be able to develop locally without any `watch` tooling, though.
 
 1. `npm install`
 1. `npm run build`
@@ -42,15 +42,15 @@ There are two ways to import dependencies, depending on your needs and preferenc
 
 1. **Locally bundled packages:** You can also bundle packages locally if you prefer, but still much faster and more conveniently than traditional approaches.
 
-   [Snowpack](https://snowpack.dev) is used to generate bundles 10x faster than Webpack, and only when needed. You don't need to run a `watch` task, just `npm run bundle` when you add/remove a dependency. It still does tree-shaking, will automatically up-convert CommonJS modules to ESM, and has a much more ergonomic approach to package locking.
+   [Snowpack](https://snowpack.dev) is used to generate bundles 10x faster than Webpack, and only when needed. You don't need to run the `watch` task, just `npm run bundle` when you add/remove a dependency. It still does tree-shaking, will automatically up-convert CommonJS modules to ESM, and has a much more ergonomic approach to package locking.
 
 
 ### Optional Tooling for Improved Developer Experience
 
 <code>npm run watch</code> will add additional features, but it's not required.
 
-* Today: Live reloading and PostCSS.
-* Future: Hot Module Reloading, React Fast Refresh.
+* Today: Hot Module Reloading and PostCSS.
+* Future: React Fast Refresh.
 
 
 ### Results
diff --git a/snowpack.config.js b/snowpack.config.js
index 7de3c38..ab0613a 100644
--- a/snowpack.config.js
+++ b/snowpack.config.js
@@ -43,8 +43,10 @@ module.exports = {
 		source: 'remote',
 	},
 
-	// Not using their localhost server because need everything to run inside WordPress/PHP context.
-	//devOptions: {},
+	devOptions: {
+		port: 8081,     // Avoid conflicts with proxies on 8080.
+		open: 'none',   // Devs will still visit the WP/PHP server URL in their browser.
+	},
 
 	buildOptions: {
 		metaUrlPath : 'vendor',
diff --git a/source/baseline/latest-posts.js b/source/baseline/latest-posts.js
index e715f0a..f9332c9 100644
--- a/source/baseline/latest-posts.js
+++ b/source/baseline/latest-posts.js
@@ -49,7 +49,7 @@ export class LatestPostsCard extends Component {
 
 	render = () => {
 		const { loaded, loading, posts } = this.state;
-		const componentUrl = getBaseUrl() + '/baseline/';
+		const componentUrl = getBaseUrl() + '/baseline';
 
 		return html`
 			<${Fragment}>
diff --git a/source/developer-experience/developer-experience.js b/source/developer-experience/developer-experience.js
index 9d76822..59f6386 100644
--- a/source/developer-experience/developer-experience.js
+++ b/source/developer-experience/developer-experience.js
@@ -12,7 +12,8 @@ import { getLoadPath, getBaseUrl } from '../utilities.js';
 
 export function DeveloperExperience() {
 	const loadPath = getLoadPath();
-	const componentUrl = getBaseUrl() + '/developer-experience/';
+	const watching = 'object' === typeof import.meta?.hot;
+	const componentUrl = getBaseUrl() + '/developer-experience';
 
 	return html`
 		<${Fragment}>
@@ -43,11 +44,23 @@ export function DeveloperExperience() {
 							</p>
 						</div>
 
-						${ 'source' === loadPath && html`
+
+						${ 'source' === loadPath && ! watching && html`
 							<${ Notice } status="info" isDismissible=${ false } >
 								<p>
-									You're running from <code>source/</code>, so the nested styles won't apply, and the image below will be blurred.
-									<code>npm run build</code> and refresh to load the <code>build/</code> files, where PostCSS will transform the nested styles to vanilla CSS and un-blur the image.
+									You're running from <code>source/</code> without the <code>watch</code> task, so the nested styles won't apply, and the image below will be blurred.
+
+									<code>npm run watch</code> or <code>npm run build</code> and then refresh. That will cause PostCSS to transform the nested styles to vanilla CSS, and un-blur the image.
+								</p>
+							<//>
+						` }
+
+						${ watching && html`
+							<${ Notice } status="info" isDismissible=${ false } >
+								<p>
+									You're running the <code>watch</code> task, so the nested styles <em>will</em> apply, and the image below will <strong>not</strong> be blurred.
+
+									<code>Control-C</code> in your terminal to cancel the watch task, then refresh to load the unprocessed files. When you do, the image will be blurred.
 								</p>
 							<//>
 						` }
diff --git a/source/index.js b/source/index.js
index 461232e..2cb72b7 100644
--- a/source/index.js
+++ b/source/index.js
@@ -5,6 +5,10 @@ const html = wp.html;
 const { Fragment } = wp.element;
 const { renderLoadingContainer } = wp.utils;
 
+// This is required for HMR to work, because we're using WP to serve the HTML instead of Snowpack's localhost server.
+if ( import.meta.hot ) {
+	import.meta.hot.accept();
+}
 
 /**
  * Internal dependencies
diff --git a/source/local-bundling/passphrase-generator.js b/source/local-bundling/passphrase-generator.js
index 994c224..a00583b 100644
--- a/source/local-bundling/passphrase-generator.js
+++ b/source/local-bundling/passphrase-generator.js
@@ -15,6 +15,7 @@ const html = wp.html;
  */
 //import { v4 as uuidv4 } from 'uuid';      // Native ESM
 //import { argon2id }     from 'hash-wasm'; // Native ESM
+// maybe change these to dynamic imports, so could flip the card on/off automatically based on import.meta.hot || build === path?
 
 // todo convert these to import maps too, but need to wait until https://github.com/snowpackjs/snowpack/discussions/2548 is released
 // then check if can destructure specific functions from any of these, since snowpack will be is bundling
@@ -140,7 +141,7 @@ export class PassphraseGenerator extends Component {
 		const dependenciesAvailable = 'function' === typeof uuidv4 && 'function' === typeof argon2id;
 		// todo add others when they're loaded from local bundle
 
-		const componentUrl = getBaseUrl() + '/local-bundling/';
+		const componentUrl = getBaseUrl() + '/local-bundling';
 
 		return html`
 			<${Fragment}>
diff --git a/source/utilities.js b/source/utilities.js
index dac32ff..ce742ee 100644
--- a/source/utilities.js
+++ b/source/utilities.js
@@ -2,7 +2,7 @@
 export function getBaseUrl() {
 	const scriptUrl = document.getElementById( 'no-build-tools-no-problems-js' ).getAttribute( 'src' );
 
-	return scriptUrl.substring( 0, scriptUrl.lastIndexOf( '/' ) ) + '/';
+	return scriptUrl.substring( 0, scriptUrl.lastIndexOf( '/' ) );
 }
 
 // Returns 'build' if loaded from `build/` folder, 'source' otherwise