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AGENT_SKILL/interface_contract_hygiene/CHECKLIST.md

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+# Checklist: interface_contract_hygiene
+
+## New Module/Package Creation
+- [ ] New module/package includes a `spec/` directory
+- [ ] `spec/interface-contract.md` file exists in the new module
+- [ ] Contract file is located at `<module_path>/spec/interface-contract.md`
+
+## Contract Content Verification
+- [ ] Contract includes a clear **Purpose** section
+- [ ] Contract identifies an **Owner** (team or individual)
+- [ ] Contract defines the **Boundary** (includes/excludes)
+- [ ] Contract specifies a **Breaking-change Policy**
+- [ ] Contract lists **Consumers** (other modules/systems that use this)
+- [ ] Contract provides **References** to related documentation
+- [ ] Contract follows the same format/structure as existing contracts in the same domain
+
+## Contract Modification (Existing Modules)
+When modifying a public API (changing function signatures, adding/removing endpoints, etc.):
+- [ ] Breaking changes follow the versioning policy:
+    - Adding features: MINOR version bump
+    - Removing/changing types: MAJOR version with migration path and 60-day notice
+- [ ] Deprecation warnings are added for removed/changed interfaces
+- [ ] Migration documentation is provided for breaking changes
+
+## Template Consistency Check
+Before creating a new contract:
+- [ ] Reviewed at least two existing interface-contract.md files in the same domain (backend/frontend/infra)
+- [ ] Matched section headings and formatting conventions
+- [ ] Used similar language and level of detail