Migrating from v1

v1 is deprecated and will be switched off on 2027-06-30.

• Pagination moved from page/per_page to cursors.
• Identifiers gained type prefixes; v1 numeric ids are accepted for one year.
• Errors now use the envelope described in Errors.
• /v1/sync was replaced by /v2/sync/pull and /v2/sync/push.
• Tags are first-class objects instead of plain strings.