APP-SIE-04 - High-change provider availability without a materialized graph

Two providers expose current availability through governed APIs. One field means “on hand”; the other means “available to promise”. Neither permits replication. The contract requires a purchasing comparison with timestamps and explicit incomplete results. SIE.4 keeps the meanings distinct and accepts only narrower qualified relations. SIE.6 composes rows where supported and returns non-comparability otherwise. SIE.8 excludes copying from the providers’ existing prohibition, then selects query-time virtual mappings subject to the receiving latency, trace, and failure conditions. The excluded copying alternative needs no implementation, recovery, or exit design. The interface exposes timeouts, source errors, timestamps, and incompatible rows.

SIE.3 can finish by reusing a model that distinguishes the two quantities, their attribution, unit, time, and horizon. If a provider later changes its promise horizon, SIE.11 finds which mappings and receiving interpretations depend on that meaning; unaffected product descriptions can retain their qualification. The purchasing application decides what to do with incomplete or non-comparable results.