whetstone_DSL/sprint139_plan.md

Sprint 139 Plan: MCP Backward Compatibility and Deprecation Governance

Context

Wiring closure must not break existing clients. Sprint 139 adds compatibility and deprecation governance for evolving MCP tool surfaces.

---

Goals

1. Define deterministic backward-compatibility policy for tool changes
2. Model deprecation lifecycle with explicit timeline states
3. Add compatibility simulation against client capability profiles
4. Publish machine-readable deprecation and migration guidance

---

Steps

Step 1629: MCP compatibility policy schema (10 tests)

Step 1630: Tool deprecation lifecycle model (10 tests)

Step 1631: Client capability profile schema (10 tests)

Step 1632: Compatibility simulation runner model (10 tests)

Step 1633: whetstone_check_tool_compatibility MCP tool (8 tests)

Step 1634: whetstone_get_tool_deprecations MCP tool (8 tests)

Step 1635: whetstone_plan_tool_migrations MCP tool (8 tests)

Step 1636: Compatibility risk packet model (8 tests)

Step 1637: Compatibility/deprecation report artifact (8 tests)

Step 1638: Sprint 139 integration summary + regression (8 tests)

---

Architecture Gate

• Compatibility simulation must be deterministic for identical profiles
• Deprecation states must be explicit and auditable
• Migration guidance must be structured and machine-readable
• Max 600 lines per header