whetstone_DSL/sprint137_plan.md

Sprint 137 Plan: Multi-Binary MCP Runtime Selection and Health Checks

Context

Workspaces may expose multiple MCP binaries (stable/dev/custom). Sprint 137 adds deterministic runtime selection and health checks to avoid accidental mismatch.

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Goals

1. Model selectable MCP runtime targets with explicit precedence
2. Add deterministic runtime health probes and compatibility checks
3. Prevent silent fallback to incompatible binaries
4. Export runtime selection decisions for automation transparency

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Steps

Step 1609: MCP runtime target descriptor schema (10 tests)

Step 1610: Runtime selection policy model (10 tests)

Step 1611: Runtime health probe runner (10 tests)

Step 1612: Runtime compatibility checker model (10 tests)

Step 1613: whetstone_list_mcp_runtimes MCP tool (8 tests)

Step 1614: whetstone_select_mcp_runtime MCP tool (8 tests)

Step 1615: whetstone_probe_mcp_runtime_health MCP tool (8 tests)

Step 1616: Runtime selection decision packet model (8 tests)

Step 1617: Runtime selection report artifact (8 tests)

Step 1618: Sprint 137 integration summary + regression (8 tests)

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Architecture Gate

• Runtime selection must be deterministic under identical inputs
• Health probes must return structured failure classes
• Compatibility checks must include explicit version/fingerprint evidence
• Max 600 lines per header