My Supabase-hosted back-end is almost finished—about 90 %—but I’m stuck on a persistent Zoho CRM integration error and the final touches of Google and Apple OAuth. The Zoho issue surfaces only on the CRM endpoint; Desk and Marketing Automation are unaffected. All environment variables, refresh tokens, and scopes are already in place, yet the call returns an authentication fault that blocks the data flow. On the OAuth side, users can sign in with Google or Apple, but token refresh and graceful error handling still need tightening so the sessions remain stable across web and mobile clients. What I need from you: • Identify and resolve the Zoho CRM API error so records can be created, updated, and fetched without failures. • Audit and harden the Google and Apple OAuth logic inside Supabase Functions, making sure refresh tokens rotate correctly and any expired-token scenarios are recovered automatically. • Provide a concise hand-off note or inline comments so I can maintain the solution later. You’ll be working with Supabase, Postgres, and the existing TypeScript functions; access to the current repo and Zoho developer console will be provided immediately. Once the CRM sync passes without errors and both OAuth flows behave reliably in QA, the job is complete.