The Old Export May Be an Undocumented Contract

A useful lesson from a software-modernization thought experiment: a feature can look obsolete and still be something another system relies on.

Imagine a team replacing an old export format. Before removing it, check who consumes it and what behavior they depend on. If that picture is incomplete, “nobody uses this” is an assumption—not a migration plan.

Keep the needed compatibility during a bounded transition, while moving the new system toward its intended format. Make dependencies visible, test the behaviors you’ve actually identified, and set a review point before retiring the old path. If the evidence is still unclear, preserve the fallback a little longer rather than turning uncertainty into an outage.

The useful change may be replacing the implementation—not breaking the contract around it.