SDK Package Seam Module owns SDK-to-get-shit-done-cc compatibility

• Status: Accepted
• Date: 2026-05-07

We decided to define one explicit SDK Package Seam Module for the @gsd-build/sdk → get-shit-done-cc transition. During this transition, install-layout probing, legacy gsd-tools.cjs discovery, legacy core.cjs discovery, and compatibility-only missing-asset diagnostics must live behind one seam instead of leaking across SDK Modules. This keeps callers thin, raises leverage for standalone-SDK testing, and improves locality by making package-readiness bugs land in one place. First tracer-bullet slice: add one compatibility Adapter Module at this seam and migrate current legacy asset callers onto it before broader native replacement work.

Runtime-global skills directory resolution is explicitly out of scope for this seam. That policy varies by runtime (claude, codex, cline, etc.) rather than by legacy package/install layout, so it now lives in a separate Runtime-Global Skills Policy Module consumed by agent-skills and skill-manifest.