Design incremental HotMem company-brain synchronization

[valiantone]

Summary

Design and implement the next step after verified clone and restore: incremental synchronization between compatible HotMem company-brain instances.

Scope

• Define delta package shape, ordering, cursor or base-package identity, and replay semantics.
• Reuse append-only event data where appropriate, but verify current event-log behavior before relying on it.
• Define idempotency, duplicate detection, conflict reporting, tombstone or deletion policy, and provenance propagation.
• Define one-way sync first. Treat multi-writer merge as a separate future decision.
• Add deterministic fixtures for replay, duplicate delivery, missing base state, and conflict handling.
• Document operational safety and recovery behavior.

Acceptance criteria

• Replaying the same delta creates no duplicates.
• A receiver detects incompatible or missing base state.
• Conflicts are visible and actionable, never silently discarded.
• Source provenance survives transfer.
• Whole-brain clone and restore remains the recovery path.
• Existing local JSONL hydrate behavior remains compatible.

Out of scope

• Real-time replication.
• Distributed consensus.
• Automatic multi-writer merge.
• Hosted synchronization.

Dependency

Verified portable company-brain dump and hydrate workflow.