ARC-002 / SOURCE CONTROLLED
Secure hybrid transition pattern
Preserve controlled legacy evidence while replacement capability is built in risk-ranked waves.
● CONTROLLEDOWNER / SYSTEM 8REVIEW / MONTHLY
Intent
- Avoid a big-bang cutover when legacy behaviour is poorly documented.
- Separate continuity requirements from target-platform selection.
- Minimise write paths into unsupported components.
Control boundary
- Pre-authentication, least privilege and explicit conditional access.
- Read-only or narrowly controlled legacy publication where justified.
- Records retention, audit and data-export controls.
- Defined expiry date and exit path for every continuity component.
Transition sequence
- Stabilise and capture evidence.
- Build the target domain model and highest-risk proof.
- Migrate capability by bounded workflow.
- Reconcile history, archive and retire the legacy path.