MartinKei

function sendReadyMessage() {
        if (window.opener) {
            // Send "ready" message to the parent window that opened this page
            window.opener.postMessage('ready', 'https://hotel.keib.dev');
            console.log('Sent "ready" message to parent window');
        } else if (window.parent && window.parent !== window) {
            // Alternative: if this page is in an iframe instead of popup
            window.parent.postMessage('ready', 'https://hotel.keib.dev');
            console.log('Sent "ready" message to parent frame');
        } else {

MartinKei

Second Code-Review

Almost all issues are gone now. Except the usage of any in the channel service nothing serious is left. The channel service looks like as if it was overlooked. The other services look just fine.

any usage where types would make sense

• channel.service.ts

Usage of inner functions