Declare the merge behavior
The ruleset states the document family, owner selector, match key, read strategy, attachment strategy, and any optional surfaces or policies.
Process
Ruleset, fixtures, implementation, review.
StructuredMerge separates the declared contract from the engine that executes it. That separation is the point.
Test it against shared fixtures
Fixtures record expected behavior and diagnostic outcomes. They are used to compare engines without treating one engine as the standard.
Run the implementation
The engine can use its own parser, data structures, and rendering path as long as the observable behavior matches the declared contract.
Preserve reviewable cases
When a merge cannot safely finish, the result can expose unresolved cases with stable review identity and replay compatibility context.