[CLAUDE] FE-Admin+Docs: Contract workflow N-stage Designer mirror PE + Docs (Chunk F)

FE Admin WorkflowsPage Designer extend mirror PeWorkflowsPage:
- Type InnerStepDto + extend StepDto +innerSteps
- Type EditInnerStep + extend EditStep +innerSteps
- copyFromDefinition include innerSteps map
- Default new step +innerSteps:[]
- departmentsList useQuery
- Save mutation payload include innerSteps Order asc
- UI sub-section "Cấp duyệt nhỏ trong phòng" drag-list per step card với
  Phòng × Cấp + required checkbox + button "+ Thêm cấp duyệt" emerald
- Empty state hint fallback 2-cấp legacy

KHÔNG đụng fe-user — WorkflowsPage admin-only.

Reuse PositionLevel const + Label maps từ Session 12 types/users.ts.

Docs:
- STATUS.md Last updated + Phase summary (19→20 mig, 89→95 test, 56→57
  bảng) + 1 row Recently Done Session 13 (KEEP narrative cũ)
- HANDOFF.md TL;DR Session 13 prepend + 7 cảnh báo Session 14+
- migration-todos.md Phase 9 + Session 13 block 5 chunk
- Session log NEW `2026-05-07-2400-n-stage-contract-mirror.md` đầy đủ
  rationale + per-chunk + bug log

Defer cron audit 2026-06-01: schema-diagram §17 Mig 20, skill
ef-core-migration row, skill contract-workflow N-stage cross-ref.

🎉 SESSION 13 COMPLETE: Mirror N-stage Contract module (Mig 20). 5
commit per-chunk + skip Chunk E auto-bind. Total 95 test pass.
Backward compat 100% với 2-stage Mig 16 legacy.

Pending Task 4: Wire BE TraLai PE transition + Task 2: Sample data seed.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

docs/changelog/migration-todos.md

@@ -157,6 +157,24 @@ Session log: `2026-04-28-chot-session-4-budget.md`.
 
 ## 📝 Phase 9 — UAT + Ops + carry over (Session 6+ active)
 
+### ✅ Session 13 done (2026-05-07) — Mirror N-stage Contract (Mig 20, 5 commit per-chunk + skip Chunk E auto-bind)
+
+User chỉ thị mirror N-stage từ PE sang Contract. Budget defer (cần migration `AddBudgetVersionedWorkflow` trước — hardcoded `BudgetPolicy.Default` chưa có WorkflowDefinition entity). Pattern reusable đầy đủ từ PE.
+
+- [x] **Chunk A (`951ffa3`)** Domain entity `WorkflowStepInnerStep` (Domain/Contracts/) + nav WorkflowStep.InnerSteps + ALTER ContractDeptApproval.InnerStepId + EF config FK Cascade Step / Restrict Dept+InnerStep + **Migration 20** `AddContractWorkflowInnerStepsAndAlterDeptApprovalUnique` GỘP 1 (CREATE TABLE WorkflowStepInnerSteps + ALTER InnerStepId + DropIndex old + Recreate filtered legacy `WHERE InnerStepId IS NULL` + new filtered N-stage `WHERE InnerStepId IS NOT NULL`).
+- [x] **Chunk B (`04cf2a0`)** Application CQRS DTO mirror PE Chunk B — `WorkflowStepInnerStepDto` + extend `WorkflowStepDto` + `CreateWorkflowStepInnerStepInput` + extend `CreateWorkflowStepInput` (default null backward compat) + Validator child rules + Handler atomic batch insert.
+- [x] **Chunk C (`e247b67`)** ContractWorkflowService refactor mirror PE — load InnerSteps eager + reject branch clear N-stage rows + dept block split hasInnerSteps→N-stage logic / else→legacy 2-stage. N-stage flow giống PE: match firstPending Order asc + (exact level OR canBypass + level≥), exact upsert / bypass batch upsert, recheck stillPending → BLOCK.
+- [x] **Chunk D (`7c0772a`)** ContractNStageApprovalTests 6 test mirror PE pattern + helper SeedWorkflowDefinitionAsync 2 step adjacent (DangGopY + DangDamPhan) + SeedContractAsync với Project + Supplier + FakeChangelogService + FakeContractCodeGenerator stubs. Bug fix legacy fallback test: switched phase pair sang DangKiemTraCCM → DangTrinhKy + role CostControl khớp Standard.Transitions. **89→95 test pass**.
+- [x] **Chunk E SKIP** — WorkflowsController auto-bind `[FromBody] CreateWorkflowDefinitionCommand` record qua JSON, no code change cần.
+- [x] **Chunk F (current)** FE WorkflowsPage Designer extend mirror PeWorkflowsPage Chunk F: InnerStepDto + EditInnerStep types + copyFromDefinition include + departmentsList query + sub-section "Cấp duyệt nhỏ trong phòng" drag-list + button "+ Thêm cấp duyệt" emerald + payload include Order asc. Empty state hint fallback 2-cấp legacy. KHÔNG đụng fe-user (admin-only).
+
+**Backward compat 100%**: workflow Contract no InnerSteps configured → service fallback legacy 2-stage Mig 16. Data legacy InnerStepId=null vẫn enforce unique cũ qua filtered index.
+
+**Defer Session 14+:**
+- [ ] **Budget N-stage** — cần migration `AddBudgetVersionedWorkflow` trước (4 bảng + ALTER Budget.WorkflowDefinitionId), sau đó migration `AddBudgetWorkflowInnerSteps`. User quyết riêng (feature mở rộng module lớn).
+- [ ] schema-diagram.md §17 Mig 20 update — defer cron audit 2026-06-01.
+- [ ] Skill ef-core-migration row Mig 20 — defer cron audit.
+
 ### ✅ Session 12 done (2026-05-07) — N-stage workflow approval (Mig 18+19, 6 commit per-chunk, PE-only)
 
 User yêu cầu: workflow level cha (= phase) cấu hình được level con (Phòng × Cấp NV/PP/TP) sequential, mỗi cấp = 1 inner step duyệt riêng, có bypass cùng dept. 6 spec defaults chốt + 6 chunk per-commit.