add firstPartyDomain for first-party isolation

src/background/messages/makeRequest.ts

@@ -3,6 +3,7 @@ import type { PlasmoMessaging } from '@plasmohq/messaging';
 import type { BaseRequest } from '~types/request';
 import type { BaseResponse } from '~types/response';
 import { removeDynamicRules, setDynamicRules } from '~utils/declarativeNetRequest';
+import { isFirefox } from '~utils/extension';
 import { makeFullUrl } from '~utils/fetcher';
 import { assertDomainWhitelist } from '~utils/storage';
 
@@ -69,6 +70,9 @@ const handler: PlasmoMessaging.MessageHandler<Request, Response<any>> = async (r
 
     const cookies = await (chrome || browser).cookies.getAll({
       url: response.url,
+      ...(isFirefox() && {
+        firstPartyDomain: new URL(response.url).hostname,
+      }),
     });
 
     res.send({

src/utils/extension.ts

@@ -1,3 +1,11 @@
 export const isChrome = () => {
   return chrome.runtime.getURL('').startsWith('chrome-extension://');
 };
+
+export const isFirefox = () => {
+  try {
+    return browser.runtime.getURL('').startsWith('moz-extension://');
+  } catch {
+    return false;
+  }
+};