Transition Approach

Avoid a big-bang migration

The architecture was designed so the intermediary could be introduced progressively.

A sensible transition pattern is:

1. deploy the edge layer without changing the source-of-truth backend;
2. route selected low-risk read endpoints through the intermediary;
3. begin in pass-through or conservative cache mode;
4. validate response compatibility with existing consumers;
5. enable caching selectively;
6. observe cache behaviour and origin usage;
7. expand coverage only where evidence supports it.

Coexistence

During transition, the existing backend continues operating normally.

This matters because it gives the architecture a stable fallback path. The edge layer can be introduced as an optimisation rather than as a forced replacement.

Risk reduction

Incremental adoption reduces several risks:

• incorrect cache identity;
• unsuitable freshness policy;
• consumer incompatibility;
• unexpected origin behaviour;
• poor observability;
• operational uncertainty.

Each endpoint can be validated before broader rollout.

Rollback principle

The simplest rollback is to bypass or disable caching and allow requests to continue to the authoritative origin.

This is a deliberate architecture property rather than an emergency workaround.

Transition outcome

The transition model supports architecture evolution through evidence:

introduce narrowly, observe behaviour, validate compatibility, then expand.

That approach is preferable to assuming every endpoint benefits equally from the same caching policy.