The Day Claude Stopped Inventing My Schedule: Injecting Ground Truth into the Vault with the Google Calendar API

Lily

Posted on Jul 10

• Originally published at dev.to

This is a follow-up to the Vault auto-ingest pipeline I mentioned in my previous post, "Turning conversation logs into skills." This time I want to write about how I killed a problem where Claude was misreading a date range as a "block of committed time" and generating a fictional schedule out of it — by injecting the actual calendar directly via the Google Calendar API.

Inside my daily brief, Claude kept interpreting a note like "Breach practicum starting 6/11" as "that entire week is fully booked," and repeatedly suggesting things like "since you'll be tied up from 6/11 onward, you should move X up." The cause was that Claude was reading a date written in the prose of a note as "occupied by an appointment for that whole period." (You can still see (2026-06-11 Breach実習)対策 — "countermeasure for the 2026-06-11 Breach practicum" — in a comment in vault-auto-ingest.sh.)