[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.Infrastructure/Persistence/Migrations/20260530034336_AddLeaveBalances.cs

@@ -0,0 +1,68 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace SolutionErp.Infrastructure.Persistence.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddLeaveBalances : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "LeaveBalances",
+                columns: table => new
+                {
+                    Id = table.Column<Guid>(type: "uniqueidentifier", nullable: false),
+                    UserId = table.Column<Guid>(type: "uniqueidentifier", nullable: false),
+                    LeaveTypeId = table.Column<Guid>(type: "uniqueidentifier", nullable: false),
+                    Year = table.Column<int>(type: "int", nullable: false),
+                    EntitledDays = table.Column<decimal>(type: "decimal(5,2)", precision: 5, scale: 2, nullable: false),
+                    UsedDays = table.Column<decimal>(type: "decimal(5,2)", precision: 5, scale: 2, nullable: false),
+                    AdjustmentDays = table.Column<decimal>(type: "decimal(5,2)", precision: 5, scale: 2, nullable: false),
+                    CreatedAt = table.Column<DateTime>(type: "datetime2", nullable: false),
+                    UpdatedAt = table.Column<DateTime>(type: "datetime2", nullable: true),
+                    CreatedBy = table.Column<Guid>(type: "uniqueidentifier", nullable: true),
+                    UpdatedBy = table.Column<Guid>(type: "uniqueidentifier", nullable: true),
+                    IsDeleted = table.Column<bool>(type: "bit", nullable: false),
+                    DeletedAt = table.Column<DateTime>(type: "datetime2", nullable: true),
+                    DeletedBy = table.Column<Guid>(type: "uniqueidentifier", nullable: true)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_LeaveBalances", x => x.Id);
+                    table.ForeignKey(
+                        name: "FK_LeaveBalances_LeaveTypes_LeaveTypeId",
+                        column: x => x.LeaveTypeId,
+                        principalTable: "LeaveTypes",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Restrict);
+                });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_LeaveBalances_LeaveTypeId",
+                table: "LeaveBalances",
+                column: "LeaveTypeId");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_LeaveBalances_UserId",
+                table: "LeaveBalances",
+                column: "UserId");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_LeaveBalances_UserId_LeaveTypeId_Year",
+                table: "LeaveBalances",
+                columns: new[] { "UserId", "LeaveTypeId", "Year" },
+                unique: true);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "LeaveBalances");
+        }
+    }
+}

src/Backend/SolutionErp.Infrastructure/Persistence/Migrations/ApplicationDbContextModelSnapshot.cs

@@ -2553,6 +2553,66 @@ namespace SolutionErp.Infrastructure.Persistence.Migrations
                     b.ToTable("Holidays", (string)null);
                 });
 
+            modelBuilder.Entity("SolutionErp.Domain.Hrm.LeaveBalance", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("uniqueidentifier");
+
+                    b.Property<decimal>("AdjustmentDays")
+                        .HasPrecision(5, 2)
+                        .HasColumnType("decimal(5,2)");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("datetime2");
+
+                    b.Property<Guid?>("CreatedBy")
+                        .HasColumnType("uniqueidentifier");
+
+                    b.Property<DateTime?>("DeletedAt")
+                        .HasColumnType("datetime2");
+
+                    b.Property<Guid?>("DeletedBy")
+                        .HasColumnType("uniqueidentifier");
+
+                    b.Property<decimal>("EntitledDays")
+                        .HasPrecision(5, 2)
+                        .HasColumnType("decimal(5,2)");
+
+                    b.Property<bool>("IsDeleted")
+                        .HasColumnType("bit");
+
+                    b.Property<Guid>("LeaveTypeId")
+                        .HasColumnType("uniqueidentifier");
+
+                    b.Property<DateTime?>("UpdatedAt")
+                        .HasColumnType("datetime2");
+
+                    b.Property<Guid?>("UpdatedBy")
+                        .HasColumnType("uniqueidentifier");
+
+                    b.Property<decimal>("UsedDays")
+                        .HasPrecision(5, 2)
+                        .HasColumnType("decimal(5,2)");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("uniqueidentifier");
+
+                    b.Property<int>("Year")
+                        .HasColumnType("int");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("LeaveTypeId");
+
+                    b.HasIndex("UserId");
+
+                    b.HasIndex("UserId", "LeaveTypeId", "Year")
+                        .IsUnique();
+
+                    b.ToTable("LeaveBalances", (string)null);
+                });
+
             modelBuilder.Entity("SolutionErp.Domain.Hrm.LeaveType", b =>
                 {
                     b.Property<Guid>("Id")
@@ -5827,6 +5887,17 @@ namespace SolutionErp.Infrastructure.Persistence.Migrations
                     b.Navigation("EmployeeProfile");
                 });
 
+            modelBuilder.Entity("SolutionErp.Domain.Hrm.LeaveBalance", b =>
+                {
+                    b.HasOne("SolutionErp.Domain.Hrm.LeaveType", "LeaveType")
+                        .WithMany()
+                        .HasForeignKey("LeaveTypeId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
+                    b.Navigation("LeaveType");
+                });
+
             modelBuilder.Entity("SolutionErp.Domain.Identity.MenuItem", b =>
                 {
                     b.HasOne("SolutionErp.Domain.Identity.MenuItem", "Parent")