A contribution is one row in a biome's manifest. The ContributionKind enum is closed (capability, shell-command, agent, skill, tool, workflow, document-template, connector-adapter, …) and each kind has a strict payload schema. At install time, the kernel writes each contribution as a contribution-entry object so the platform always knows who declared what. Contributions are self-describing: they declare required capabilities, execution environments, and any companion resources. They are also the lockfile substrate — the lockfile pins exact versions of every contribution at install time so subsequent boots are deterministic.