SYSE.27:4.3 - Make contribution possible at the supported boundary

State what a contributor may change and what remains controlled by the provider. Supply a reproducible way to exercise the interaction, examples of supported old and new use, relevant acceptance checks, and enough failure information for a contributor to repair a rejected proposal.

Make dependencies explicit: a contribution may require a toolchain, resource, permission or domain Method not yet supplied. Preserve the distinction between a technically valid proposal, an accepted contribution and a deployed provision. A contribution test should not expose release credentials or unrestricted provider access.

Choose a maintained extension point only where independently changing use justifies it. A small parameter or documented composition may be enough; an open-ended plugin system can cost more to secure, qualify and support than the variants it enables.