Use case:

• website opens an extension popup window when a user clicks on a button
• user performs some actions in the extension popup
• a result of that action is sent back to the browser tab which initially opened the extension

Approach

(1) window.postMessage(data): Send a message to the content script where window.addEventListener("message", (event) => {...} is receiving the message event.

(2) chrome.runtime.sendMessage(event.data, function(response) {...}: This functionality is in the listener above and forwards the message to the background script where chrome.runtime.onMessage.addListener(function(request, sender, sendResponse) {...}) is receiving the message.

(3) Background scripts opens the extension as a dedicated popup window:

chrome.windows.getLastFocused().then((window) => {
    const width = 600 + 100;
    const height = 400 + 100;
    const left = window.width - width;
    chrome.windows.create({url: path, type: "popup", height: height, width: width, left: left, focused: true});
    });

(4) After having processed some user actions within the extension popup a response message should be returned to the content script:

chrome.tabs.query({active: true, currentWindow: true}, function(tabs) {
    chrome.tabs.sendMessage(tabs[0].id, {...})}

Problem

Everything works fine up to step (4). Because the extension popup has been opened programmatically as a dedicated popup window tabs[0].id contains a tab id from the extension popup window instead of the browser window which triggered the whole flow and where the content script runs.

• How can the correct tab id be determined or forwarded along the chain to the popup?
• Is this messaging scenario the right approach for my requirements?

Any feedback is very much appreciated!