state-sync uses a simple and reliable pattern:

1. Invalidation event indicates that the state “may have changed” and carries:
   • topic
   • revision
2. The receiver does a pull: provider.getSnapshot()
3. The engine applies the snapshot only if it is newer (revision gate).

Why:

• events can arrive out of order
• events can be lost
• the snapshot remains the source of truth

InvalidationEvent

Minimal contract:

• topic: string
• revision: Revision (canonical decimal u64 string)

SnapshotEnvelope

Minimal contract:

• revision: Revision
• data: T

What is a protocol error

The engine reports phase='protocol' when:

• topic is empty / not a string
• revision is not canonical ("01", "abc", etc.)

See Troubleshooting and Lifecycle.