[CLAUDE] Workflow: LeaveBalance business logic — trừ phép khi duyệt + số dư (Phase 11 P11-B)

Số dư phép theo (User × LeaveType × Year) + trừ tự động khi đơn nghỉ duyệt cuối.
Policy: cho phép vượt số dư (âm) + cảnh báo (anh main chốt), tích hợp vào trang đơn nghỉ.

Schema (Mig 42 AddLeaveBalances — pure additive, 1 bảng):
- LeaveBalance: UserId + LeaveTypeId + Year + EntitledDays + UsedDays + AdjustmentDays.
  UNIQUE (UserId,LeaveTypeId,Year), FK LeaveType Restrict, decimal(5,2).
  Remaining = Entitled + Adjustment − Used (computed, không store).

Deduction hook (ApproveLeaveRequestHandler nhánh terminal DaDuyet — exactly-once):
- Upsert LeaveBalance(RequesterUserId, LeaveTypeId, StartDate.Year), auto-create từ
  LeaveType.DaysPerYear, UsedDays += NumDays. Guard Status!=DaGuiDuyet chặn re-approve.

FK invariant guard (em main thêm sau test reveal FK risk):
- Create + UpdateDraft validate LeaveTypeId tồn tại (AnyAsync) → ConflictException.
  Đóng cửa vào — bogus type không thể tới deduction FK insert (tránh 500 kẹt đơn).

CQRS LeaveBalanceFeatures.cs: GetMy (self, lazy merge active LeaveType) + GetUser (admin)
  + AdjustLeaveBalance (admin upsert carry-over). Controller [Authorize] + admin Roles=Admin.
Embed: GetLeaveRequestByIdHandler trả balance NGƯỜI TẠO (approver xem thấy đúng).
FE: WorkflowAppDetailPage ×2 — block "Số dư phép" + cảnh báo vượt khi kind=leave (SHA256 identical).

Tests (+11, 130→154 PASS): deduction single/multi-level/accumulate/negative-allowed/
  reject-return-no-deduct + lazy-merge + adjust upsert + Create guard bogus→Conflict.
  Cũng repair 2 test S42 terminal FK-fail (template BuildLeave +seed LeaveType).

Verify: build 0 error · 154 test · FE ×2 · reviewer Max PASS (deduction exactly-once +
  FK invariant fully closed, 2 minor concurrency/comment defer).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.claude/agent-memory/implementer-frontend/MEMORY.md

@@ -42,7 +42,8 @@ Dynamic class purged. PALETTE array full literal `as const` cycle `index % lengt
 
 ## 📅 Recent activity (last 10 FIFO)
 
-- **2026-05-29 (S39 agent split setup):** NEW agent từ split implementer. Seeded FE patterns (16-bis 9× + SHA256 mirror + KIND_CONFIG + Tailwind palette + PageHeader S37). Prior FE work absorbed: S33 EmployeesListPage + S34 Directory + S35 HrmConfigs declarative + S36 MeetingCalendar + S37 Proposal + S38 WorkflowApps generic. First dedicated spawn pending em main S39+ FE task.
+- **2026-05-30 (S42 P11-B Wave 2 — leave balance display):** WorkflowAppDetailPage.tsx + workflowApps.ts (2 app SHA256 identical). +3 optional `leaveBalance{Entitled,Used,Remaining}?: number|null` trong `// leave` block (BE `decimal?` → camelCase). Block "Số dư phép" sau Section 1 IIFE `kind==='leave' && d.leaveBalanceRemaining != null`: year từ StartDate, banner amber/red khi `remaining<0 || (status!==DaDuyet && remaining<numDays)`. Case 1, KHÔNG 4-place (enrich existing page). cp fe-admin→fe-user. Build PASS ×2 (page 8ef83e4b, type 1c4f167a). Lesson reuse: IIFE inline `(() => {...})()` cho conditional block có derived vars — sạch hơn tách helper.
+- **2026-05-29 (S39 agent split setup):** NEW agent từ split implementer. Seeded FE patterns (16-bis 9× + SHA256 mirror + KIND_CONFIG + Tailwind palette + PageHeader S37). Prior FE work absorbed: S33 EmployeesListPage + S34 Directory + S35 HrmConfigs declarative + S36 MeetingCalendar + S37 Proposal + S38 WorkflowApps generic.
 
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