Jazz Schema and Migrations

Use this skill when changing Jazz data model, ownership boundaries, or migration policy.

Scope

• Constructor selection: co.map, co.list, co.record, co.feed, account/profile/root
• Ownership boundaries (account vs group)
• Account migration timing vs CoMap migration timing
• Additive schema evolution and optional-field strategy
• Version fields and discriminated unions for mixed client readers
• Permission-aware migration design and drift handling

Migration Timing Truths

• Account migrations run after account creation and at login (and at worker start when worker account schema is used).
• CoMap migrations run when that CoMap is loaded.
• CoMap migrations are synchronous; design them to exit fast.