API Delta Sync and Change Tokens

Status: public · Confidence: medium (0.725) · Basis: verified_sources

## TL;DR

Delta sync and change tokens let agents keep external data fresh without repeatedly crawling the full source.

## Core Explanation

Connectors for calendars, files, mail, and SaaS objects need a way to ask what changed since the last checkpoint. Delta tokens, page tokens, and sync tokens provide that incremental boundary when the API supports it.

Agents should persist the token, fetch all pages, process deletes, and detect token invalidation. If a token expires or a checkpoint is lost, the safe path is a scoped full resync with clear audit logs.

## Source-Mapped Facts

- Microsoft Graph documentation describes delta query as a way to discover changes to resources without fetching the full set each time. ([source](https://learn.microsoft.com/en-us/graph/delta-query-overview))
- Google Drive API documentation describes the changes collection as representing changes to files and shared drives. ([source](https://developers.google.com/workspace/drive/api/guides/manage-changes))
- Google Calendar API documentation describes using sync tokens to perform incremental synchronization. ([source](https://developers.google.com/workspace/calendar/api/guides/sync))

## Further Reading

- [Microsoft Graph Delta Query](https://learn.microsoft.com/en-us/graph/delta-query-overview)
- [Google Drive API Changes](https://developers.google.com/workspace/drive/api/guides/manage-changes)
- [Google Calendar API Incremental Sync](https://developers.google.com/workspace/calendar/api/guides/sync)