Structured collection of section-based contract mutations. It divides `/contracts` changes into `add`, `modify`, and `remove` lists so a workflow can validate and apply them coherently under Contracts Change Policy. `add` creates new Document Section markers and their related contracts. `modify` replaces an existing section's marker and related contracts with a full new section definition. `remove` deletes a section key and the contracts listed as related to that section. The exact patch sequence is produced by the supporting workflow, but the semantic intent is section-level contract evolution rather than low-level pointer editing. This type is useful for human review, AI-agent proposal validation, and audit trails because it preserves why a set of contract changes belong together.