Operational State Is Disposable
If immutable events are the constitutional memory of a system, projections are its working memory. They exist to make operations efficient—not to replace constitutional history.
Events are permanent.
Projections are rebuildable.
Why Projections Exist
Reading millions of historical events for every request is impractical. Projection engines derive optimized read models from immutable event streams while leaving the original constitutional record unchanged.
| Event Ledger | Projection |
|---|---|
| Immutable source of truth | Derived operational view |
| Append-only | Rebuildable at any time |
| Replay input | User-facing state |
| Historical lineage | Current operational snapshot |
Disposable by Design
A projection should never become the constitutional source of truth. If corruption, schema changes, or failures occur, the projection is discarded and reconstructed from verified events.
- Rebuild after failure.
- Create multiple read models.
- Support dashboards and analytics.
- Maintain separation between history and presentation.
Projection Drift
Operational views may diverge from the ledger because of software defects, interrupted processing, or environmental failures. Replay provides an objective method to detect and correct projection drift.
Governance Benefits
- Fast operational queries.
- Multiple domain-specific views.
- No loss of constitutional history.
- Safe recovery after defects.
- Independent verification through replay.
Architectural Principle
Applications interact primarily with projections for performance, while governance decisions continue to rely on immutable constitutional events and runtime verification.
Chapter Conclusion
Projection engines separate operational convenience from constitutional truth. By treating projections as disposable and the event ledger as authoritative, CEI achieves both scalability and governance integrity.
Next Chapter: Constitutional Ledgers — Designing immutable evidence chains for long-term operational accountability.