2 way calender + AI Bookng

What we looked at Option Verdict Pull their Google/Outlook secret ICS link ✗ Won't work — those feeds are cached hours behind. Your voice agent would book over real conflicts. Full 2-way OAuth (read and write their calendar) Works, but you don't need it — see below. One-way OAuth read + your existing ICS feed for the write ✓ This one. Push notifications instead of polling ✓ Layer on top — removes all latency from calls. The recommendation, in one line: read their busy times via OAuth, and keep using the ICS feed you already ship to put your bookings into their calendar. That's two-way in effect, one-way in both directions. Is full 2-way too much effort? The code isn't the problem — writing to their calendar adds maybe a day, plus echo suppression so your own writes don't bounce back at you. The real cost is Google verification: writing needs broader scopes than free/busy, which means a harder review and a longer wait. So it's not "too hard" — it's poor value. You'd take on the bigger approval hurdle and the loop problem to solve something already solved: your ICS feed and per-booking email attachments already put jobs in their calendar today. Why push matters: without it, the agent fetches free/busy mid-call and adds ~200ms to a turn you're paying Vapi to keep fast. With it, Google tells you when things change, your cache is already correct, and the call reads local Firestore — zero delay. What actually gets built: Google OAuth connect per host (start verification early — it's the long pole) Cache their busy blocks in Firestore Watch channels for push + a daily renewal cron (fits your existing QStash setup) Merge that busy data into the three places that already compute it Query primary only — never the LeadStack feed calendar Outlook is the same shape, added later once Google works.

Found. out that voice AI reads and books the calender - Txt chat will sending bookign form link. So itsa the 2 way sync of calenders