H.5.1 Shared Components

Shared code is a product for internal consumers, not merely a reachable directory.

• Define supported surfaces, intended consumers, stability, stewardship, deprecation, and change evidence.
• Choose a facade, source dependency, generated client, published artifact, or deliberate duplication from the real coordination boundary.
• Keep implementation detail private where the language and graph permit it without prescribing one cross-language mechanism.
• Use fan-out and consumer influence to set the strength of the evolution contract.
• Co-location enables atomic source change but does not remove external consumers, runtime skew, independent delivery, or documentation.