Wire compatibility

This page is for contributors changing the synchronization protocol.

Scheme versions

Subjects and durable consumer identities embed a scheme version. A breaking change must use a new scheme instead of silently reinterpreting stored events from an older release.

Compatibility rules

New readers must reject envelopes whose required scheme or algorithm is unsupported.
Cryptographic algorithm identifiers are authenticated and must not be treated as cosmetic metadata.
Durable consumer names must remain stable within a scheme so reconnecting peers continue from the correct position.
Enrollment credentials remain scoped to the PAKE exchange and cannot subscribe to project data.

Change checklist

Before changing the wire format, update protocol constants, migration behavior, mixed-version tests, security documentation, and the black-box end-to-end suite. Never reuse an existing scheme number for an incompatible meaning.