Read first, write later

The safe first version of a bridge is read-only. It exposes the legacy data as clean REST resources and changes nothing. That alone unlocks reporting, search and a CRM feed, and it lets you validate your understanding of the schema before you risk a write.

Controlled writes through a narrow surface

When writes are needed, expose the smallest possible set of operations — “set delivery date”, not “update job” — each one validated and logged. The legacy database keeps its own integrity rules; the wrapper never bypasses them with raw SQL.

The wrapper is not a source of truth

The failure mode to avoid is the bridge quietly accumulating state — a cache that becomes the real data, a status field only it maintains. Every value the wrapper serves must be traceable to the legacy system or to the platform on the other side.