WHMCS Domain availability present in domain checker & SSO Fix

I’m running WHMCS for billing and domains while a custom domain-checker lives inside my WordPress site. Visitors get correct availability results, but the prices shown are static and quickly fall out of date. I need the checker to call WHMCS (GetTLDPricing or equivalent) so every lookup displays the real-time price that matches my WHMCS catalogue.

At the same time my Google-based single sign-on only logs users into WordPress; the WHMCS session never starts, which forces a second login. I’d like the same Google OAuth click to create or match the WHMCS client record and open a valid session there as well.

Once these two items are solid I’ll move on to broader client-portal cleanup, so clean, well-commented code is important.

Deliverables
• Integrate WHMCS availability data into the existing WordPress domain-checker and show live figures beside availability results.
• Repair the Google SSO bridge so one sign-in lands the user simultaneously in WordPress and WHMCS, with sessions staying in sync.
• Provide concise setup notes and any code snippets, hooks, or template edits necessary for future deployments.

Access details for WHMCS admin, WordPress (cPanel/SSH), and a Google Cloud OAuth project are ready; please work in a staging clone first and hand over when everything passes live tests.