docs: plan backend foundation phase

.planning/STATE.md

@@ -19,18 +19,22 @@ interview-ready after each short practice loop.
 - Source files should stay at or below 600 lines.
 - SOLID, KISS, and YAGNI are active implementation constraints.
 - OpenSpec is the intent/requirements source of truth.
+- First interview track is Backend Developer Interview.
+- Phase 1 has context, research, and plan artifacts.
 
 ## Next Actions
 
-1. Choose first interview track and canonical concept seed list.
-2. Define typed contracts for diagnostic, grading, memory extraction, next
-   challenge, readiness update, ontology gap, and asset prompt.
-3. Plan Phase 1 with GSD before writing backend code.
+1. Execute Phase 1 Go backend foundation plan.
+2. Keep `docs/planning/WORKFLOW_CONTRACTS.md` aligned with Go structs during
+   implementation.
+3. After Phase 1, plan Phase 2 diagnostic interview loop.
 
 ## Validation Log
 
 - 2026-04-26: `openspec validate bootstrap-job-tutor-platform --strict` passed
   before GSD planning docs were created.
+- 2026-04-26: First track, workflow contracts, and Phase 1 GSD plan were
+  created.
 
 ---
 *State initialized: 2026-04-26.*