1. Declare
A .smrules file declares the merge family, owner selector, matching strategy, read/write behavior, attachment behavior, and optional semantic surfaces.
Model
Rulesets describe behavior; fixtures prove it.
StructuredMerge separates semantic contracts from fixture payloads and implementation internals.
2. Exercise
A JSON fixture provides the template, destination, and expected output that exercise the declared behavior.
3. Compare
Each implementation parses the same contract and runs the same fixture so differences become visible.