Avoid duplicate injections in MV3 workers

package.json

@@ -45,6 +45,8 @@
 	},
 	"dependencies": {
 		"webext-content-scripts": "^2.6.0",
+		"webext-detect-page": "^5.0.1",
+		"webext-events": "^2.2.1",
 		"webext-polyfill-kinda": "^1.0.2"
 	},
 	"devDependencies": {

source/inject.ts

@@ -1,4 +1,5 @@
 import {injectContentScript, isScriptableUrl} from 'webext-content-scripts';
+import {isPersistentBackgroundPage} from 'webext-detect-page';
 import chromeP from 'webext-polyfill-kinda';
 
 const acceptableInjectionsCount = 10;
@@ -42,11 +43,8 @@ function onActivated({tabId}: {tabId: number}) {
 	}
 }
 
-const background = globalThis.chrome?.runtime.getManifest().background;
-const permissions = globalThis.chrome?.runtime.getManifest().permissions;
-const isPersistentBackgroundPage = background && !('service_worker' in background) && background.persistent !== false;
-
 export default async function progressivelyInjectScript(contentScript: ContentScript) {
+	const permissions = globalThis.chrome?.runtime.getManifest().permissions;
 	if (!permissions?.includes('tabs')) {
 		throw new Error('webext-inject-on-install: The "tabs" permission is required');
 	}
@@ -60,8 +58,9 @@ export default async function progressivelyInjectScript(contentScript: ContentSc
 		return;
 	}
 
-	// TODO: Non-persistent pages support via chrome.storage.session https://github.com/fregante/webext-dynamic-content-scripts/issues/1
-	const singleInjection = !isPersistentBackgroundPage || scriptableTabs.length <= acceptableInjectionsCount;
+	// TODO: Non-persistent pages support via chrome.storage.session
+	// https://github.com/fregante/webext-inject-on-install/issues/4
+	const singleInjection = !isPersistentBackgroundPage() || scriptableTabs.length <= acceptableInjectionsCount;
 	console.debug('webext-inject-on-install: Single injection?', singleInjection);
 
 	for (const tab of scriptableTabs) {

source/register.ts

@@ -1,15 +1,18 @@
+import {onExtensionStart} from 'webext-events';
 import progressivelyInjectScript from './inject.js';
 
 if (globalThis.chrome && !navigator.userAgent.includes('Firefox')) {
-	const {content_scripts: scripts} = chrome.runtime.getManifest();
+	onExtensionStart.addListener(() => {
+		const {content_scripts: scripts} = chrome.runtime.getManifest();
 
-	if (!scripts?.length) {
-		throw new Error('webext-inject-on-install tried to inject content scripts, but no content scripts were found in the manifest.');
-	}
+		if (!scripts?.length) {
+			throw new Error('webext-inject-on-install tried to inject content scripts, but no content scripts were found in the manifest.');
+		}
 
-	console.debug('webext-inject-on-install: Found', scripts.length, 'content script(s) in the manifest.');
+		console.debug('webext-inject-on-install: Found', scripts.length, 'content script(s) in the manifest.');
 
-	for (const contentScript of scripts) {
-		void progressivelyInjectScript(contentScript);
-	}
+		for (const contentScript of scripts) {
+			void progressivelyInjectScript(contentScript);
+		}
+	});
 }