Environment parity
Also called: staging–production parity, prod-like environment, environment drift
Environment parity is how closely a test environment matches production in the things that affect user journeys: configuration, integrations, data and versions.
Evidence from a test environment is only as good as that environment’s resemblance to production. Parity does not mean identical. It means the same feature flags, the same integration endpoints or honest stubs, the same authentication, and data with the same shape.
The classic false positive is an interface that passes every check while wired to the wrong backend. Differences nobody wrote down are the dangerous ones.
I keep a short parity list for the journeys in scope and state the known differences in the readiness note. Stakeholders can still choose to ship, and they should know what the evidence does not cover.