Resolve hosted magic-link verification through current organization membership so sessions bind to the stored stable user principal instead of token email.
Add the v6 identity invariant contract and static guards covering hosted handoff, checkout, provisioning, and magic-link boundaries.
Use stable control-plane user IDs as hosted tenant organization principals while preserving email as contact metadata and legacy fallback. Cloud handoff sessions now bind to the signed subject instead of email, seeded tenant orgs store owner/member email separately from durable user IDs, and the subsystem contracts pin that boundary.
rcourtman