[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>

src/Backend/SolutionErp.Api/Controllers/LeaveBalancesController.cs

@@ -0,0 +1,42 @@
+using MediatR;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using SolutionErp.Application.Common.Interfaces;
+using SolutionErp.Application.Hrm;
+
+namespace SolutionErp.Api.Controllers;
+
+// Phase 11 P11-B Wave 1 (Mig 42 — S43) — Số dư phép theo năm.
+// /my = mọi user đăng nhập (xem phép của chính mình). Admin endpoint (xem user khác +
+// điều chỉnh) dùng [Authorize(Roles = "Admin")] — mirror HrmConfigsController convention
+// (HRM write/admin = Roles "Admin", KHÔNG menu policy).
+[ApiController]
+[Route("api/leave-balances")]
+[Authorize]
+public class LeaveBalancesController(IMediator mediator, IDateTime clock) : ControllerBase
+{
+    [HttpGet("my")]
+    public async Task<IActionResult> GetMy([FromQuery] int? year)
+        => Ok(await mediator.Send(new GetMyLeaveBalancesQuery(year ?? clock.Now.Year)));
+
+    [HttpGet]
+    [Authorize(Roles = "Admin")]
+    public async Task<IActionResult> GetForUser([FromQuery] Guid userId, [FromQuery] int? year)
+        => Ok(await mediator.Send(new GetUserLeaveBalancesQuery(userId, year ?? clock.Now.Year)));
+
+    [HttpPut("adjust")]
+    [Authorize(Roles = "Admin")]
+    public async Task<IActionResult> Adjust([FromBody] AdjustLeaveBalanceBody body)
+    {
+        await mediator.Send(new AdjustLeaveBalanceCommand(
+            body.UserId, body.LeaveTypeId, body.Year, body.EntitledDays, body.AdjustmentDays));
+        return NoContent();
+    }
+
+    public record AdjustLeaveBalanceBody(
+        Guid UserId,
+        Guid LeaveTypeId,
+        int Year,
+        decimal? EntitledDays,
+        decimal? AdjustmentDays);
+}