[CLAUDE] Domain+Infra: Migration 20 Contract workflow inner steps mirror PE (Chunk A)

Mirror PE N-stage Mig 18+19 pattern sang Contract module. Gộp 1 migration
(CREATE TABLE + ALTER + filtered unique alter) thay vì tách 2 như PE.

Schema:
- entity WorkflowStepInnerStep (Domain/Contracts/) — Order, DeptId,
  PositionLevel, Name, SlaDays, IsRequired
- WorkflowStep nav +InnerSteps List
- ContractDepartmentApproval +InnerStepId Guid? FK Restrict
- CREATE TABLE WorkflowStepInnerSteps (no Contract prefix vì module dùng
  entity gốc Workflow* từ Mig 8)
- DROP UX_ContractDeptApprovals_Contract_Phase_Dept_Stage cũ
- RECREATE filtered: WHERE InnerStepId IS NULL (legacy 2-stage Mig 16)
  + new filtered UNIQUE (ContractId, Phase, InnerStepId) WHERE InnerStepId
  IS NOT NULL (N-stage)
- 3 INDEX: IX_InnerStepId, IX_(StepId, Order), IX_DeptId

Backward compat 100%: workflow Contract no InnerSteps configured →
service fallback legacy 2-stage. Data legacy InnerStepId=null vẫn enforce
unique cũ qua filtered index.

Note: Budget defer (chưa có versioned WorkflowDefinition entity —
hardcoded BudgetPolicy.Default). Cần migration AddBudgetVersionedWorkflow
trước khi mirror N-stage Budget.

Verify:
- dotnet build SolutionErp.slnx 0 error
- dotnet ef database update LocalDB applied OK
- dotnet test 89 pass (54 + 35) — no regression

Pending Chunk B: WorkflowAdminFeatures.cs DTO/Input/Validator/Handler
extend mirror PE Chunk B pattern.

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

src/Backend/SolutionErp.Domain/Contracts/ContractDepartmentApproval.cs

@@ -23,5 +23,9 @@ public class ContractDepartmentApproval : AuditableEntity
     public DateTime ApprovedAt { get; set; }
     public bool IsBypassed { get; set; }                    // true nếu NV bypass (User.CanBypassReview=true)
 
+    // N-stage inner step link (Mig 20) — null cho data legacy 2-stage Review/Confirm.
+    // Có giá trị khi step cha có InnerSteps configured. Mirror PE Mig 18 pattern.
+    public Guid? InnerStepId { get; set; }
+
     public Contract? Contract { get; set; }
 }

src/Backend/SolutionErp.Domain/Contracts/WorkflowDefinition.cs

@@ -1,4 +1,5 @@
 using SolutionErp.Domain.Common;
+using SolutionErp.Domain.Identity;     // reuse PositionLevel
 
 namespace SolutionErp.Domain.Contracts;
 
@@ -32,6 +33,11 @@ public class WorkflowStep : BaseEntity
 
     public WorkflowDefinition? WorkflowDefinition { get; set; }
     public List<WorkflowStepApprover> Approvers { get; set; } = new();
+
+    // Inner steps (Mig 20) — N-stage approval Phòng × PositionLevel sequential.
+    // Mirror PE pattern (Mig 18). Empty list → service fallback logic 2-stage
+    // Review/Confirm legacy (Mig 16) per dept.
+    public List<WorkflowStepInnerStep> InnerSteps { get; set; } = new();
 }
 
 public enum WorkflowApproverKind
@@ -48,3 +54,23 @@ public class WorkflowStepApprover : BaseEntity
 
     public WorkflowStep? Step { get; set; }
 }
+
+// Inner step (Mig 20 — Phase 9+) — sub-step level con cấu hình bên trong 1
+// WorkflowStep cha (= 1 phase). Mirror PurchaseEvaluationWorkflowStepInnerStep
+// pattern (Mig 18). Cho phép admin định nghĩa thứ tự duyệt N-stage theo
+// Department × PositionLevel: NV.A → PP.A → TP.A → NV.B → PP.B → TP.B → ...
+//
+// User khớp DepartmentId + PositionLevel + Order tiếp theo chưa duyệt = approver
+// hợp lệ. CanBypassReview ở User cho TP skip NV+PP cùng dept (audit IsBypassed).
+public class WorkflowStepInnerStep : BaseEntity
+{
+    public Guid WorkflowStepId { get; set; }
+    public int Order { get; set; }
+    public Guid DepartmentId { get; set; }
+    public PositionLevel PositionLevel { get; set; }            // NV / PP / TP
+    public string? Name { get; set; }                            // hiển thị FE — vd "NV.PRO duyệt"
+    public int? SlaDays { get; set; }
+    public bool IsRequired { get; set; } = true;
+
+    public WorkflowStep? Step { get; set; }
+}

src/Backend/SolutionErp.Infrastructure/Persistence/ApplicationDbContext.cs

@@ -41,6 +41,7 @@ public class ApplicationDbContext
     public DbSet<WorkflowDefinition> WorkflowDefinitions => Set<WorkflowDefinition>();
     public DbSet<WorkflowStep> WorkflowSteps => Set<WorkflowStep>();
     public DbSet<WorkflowStepApprover> WorkflowStepApprovers => Set<WorkflowStepApprover>();
+    public DbSet<WorkflowStepInnerStep> WorkflowStepInnerSteps => Set<WorkflowStepInnerStep>();
     public DbSet<ThauPhuDetail> ThauPhuDetails => Set<ThauPhuDetail>();
     public DbSet<GiaoKhoanDetail> GiaoKhoanDetails => Set<GiaoKhoanDetail>();
     public DbSet<NhaCungCapDetail> NhaCungCapDetails => Set<NhaCungCapDetail>();

src/Backend/SolutionErp.Infrastructure/Persistence/Configurations/DepartmentApprovalsConfiguration.cs

@@ -27,9 +27,19 @@ public class ContractDepartmentApprovalConfiguration
         b.Property(x => x.ApproverRoleSnapshot).HasMaxLength(100);
         b.Property(x => x.Comment).HasMaxLength(1000);
 
+        // Legacy 2-stage rows (Mig 16): UNIQUE chỉ áp khi InnerStepId IS NULL
+        // (Mig 20 mirror PE Mig 19 filtered split).
         b.HasIndex(x => new { x.ContractId, x.PhaseAtApproval, x.DepartmentId, x.Stage })
             .IsUnique()
+            .HasFilter("[InnerStepId] IS NULL")
             .HasDatabaseName("UX_ContractDeptApprovals_Contract_Phase_Dept_Stage");
+
+        // N-stage rows (Mig 20): UNIQUE 1 row per (phase × inner step).
+        b.HasIndex(x => new { x.ContractId, x.PhaseAtApproval, x.InnerStepId })
+            .IsUnique()
+            .HasFilter("[InnerStepId] IS NOT NULL")
+            .HasDatabaseName("UX_ContractDeptApprovals_Contract_Phase_InnerStep");
+
         b.HasIndex(x => x.ContractId);
         b.HasIndex(x => x.DepartmentId);
         b.HasIndex(x => x.ApproverUserId);
@@ -38,6 +48,12 @@ public class ContractDepartmentApprovalConfiguration
             .WithMany(c => c.DepartmentApprovals)
             .HasForeignKey(x => x.ContractId)
             .OnDelete(DeleteBehavior.Cascade);
+
+        // FK InnerStepId nullable — Restrict (không xóa InnerStep nếu còn approval row)
+        b.HasOne<WorkflowStepInnerStep>()
+            .WithMany()
+            .HasForeignKey(x => x.InnerStepId)
+            .OnDelete(DeleteBehavior.Restrict);
     }
 }
 

src/Backend/SolutionErp.Infrastructure/Persistence/Configurations/WorkflowDefinitionConfiguration.cs

@@ -52,3 +52,31 @@ public class WorkflowStepApproverConfiguration : IEntityTypeConfiguration<Workfl
             .OnDelete(DeleteBehavior.Cascade);
     }
 }
+
+// Inner step (Mig 20) — N-stage approval cấu hình động trong cùng 1 phase.
+// Mirror PurchaseEvaluationWorkflowStepInnerStepConfiguration (Mig 18).
+public class WorkflowStepInnerStepConfiguration
+    : IEntityTypeConfiguration<WorkflowStepInnerStep>
+{
+    public void Configure(EntityTypeBuilder<WorkflowStepInnerStep> e)
+    {
+        e.ToTable("WorkflowStepInnerSteps");
+        e.HasKey(x => x.Id);
+
+        e.Property(x => x.PositionLevel).HasConversion<int>();
+        e.Property(x => x.Name).HasMaxLength(200);
+
+        e.HasOne(x => x.Step)
+            .WithMany(s => s.InnerSteps)
+            .HasForeignKey(x => x.WorkflowStepId)
+            .OnDelete(DeleteBehavior.Cascade);
+
+        e.HasOne<SolutionErp.Domain.Master.Department>()
+            .WithMany()
+            .HasForeignKey(x => x.DepartmentId)
+            .OnDelete(DeleteBehavior.Restrict);
+
+        e.HasIndex(x => new { x.WorkflowStepId, x.Order });
+        e.HasIndex(x => x.DepartmentId);
+    }
+}

src/Backend/SolutionErp.Infrastructure/Persistence/Migrations/20260507115947_AddContractWorkflowInnerStepsAndAlterDeptApprovalUnique.cs

@@ -0,0 +1,129 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace SolutionErp.Infrastructure.Persistence.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddContractWorkflowInnerStepsAndAlterDeptApprovalUnique : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropIndex(
+                name: "UX_ContractDeptApprovals_Contract_Phase_Dept_Stage",
+                table: "ContractDepartmentApprovals");
+
+            migrationBuilder.AddColumn<Guid>(
+                name: "InnerStepId",
+                table: "ContractDepartmentApprovals",
+                type: "uniqueidentifier",
+                nullable: true);
+
+            migrationBuilder.CreateTable(
+                name: "WorkflowStepInnerSteps",
+                columns: table => new
+                {
+                    Id = table.Column<Guid>(type: "uniqueidentifier", nullable: false),
+                    WorkflowStepId = table.Column<Guid>(type: "uniqueidentifier", nullable: false),
+                    Order = table.Column<int>(type: "int", nullable: false),
+                    DepartmentId = table.Column<Guid>(type: "uniqueidentifier", nullable: false),
+                    PositionLevel = table.Column<int>(type: "int", nullable: false),
+                    Name = table.Column<string>(type: "nvarchar(200)", maxLength: 200, nullable: true),
+                    SlaDays = table.Column<int>(type: "int", nullable: true),
+                    IsRequired = table.Column<bool>(type: "bit", 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)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_WorkflowStepInnerSteps", x => x.Id);
+                    table.ForeignKey(
+                        name: "FK_WorkflowStepInnerSteps_Departments_DepartmentId",
+                        column: x => x.DepartmentId,
+                        principalTable: "Departments",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Restrict);
+                    table.ForeignKey(
+                        name: "FK_WorkflowStepInnerSteps_WorkflowSteps_WorkflowStepId",
+                        column: x => x.WorkflowStepId,
+                        principalTable: "WorkflowSteps",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_ContractDepartmentApprovals_InnerStepId",
+                table: "ContractDepartmentApprovals",
+                column: "InnerStepId");
+
+            migrationBuilder.CreateIndex(
+                name: "UX_ContractDeptApprovals_Contract_Phase_Dept_Stage",
+                table: "ContractDepartmentApprovals",
+                columns: new[] { "ContractId", "PhaseAtApproval", "DepartmentId", "Stage" },
+                unique: true,
+                filter: "[InnerStepId] IS NULL");
+
+            migrationBuilder.CreateIndex(
+                name: "UX_ContractDeptApprovals_Contract_Phase_InnerStep",
+                table: "ContractDepartmentApprovals",
+                columns: new[] { "ContractId", "PhaseAtApproval", "InnerStepId" },
+                unique: true,
+                filter: "[InnerStepId] IS NOT NULL");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_WorkflowStepInnerSteps_DepartmentId",
+                table: "WorkflowStepInnerSteps",
+                column: "DepartmentId");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_WorkflowStepInnerSteps_WorkflowStepId_Order",
+                table: "WorkflowStepInnerSteps",
+                columns: new[] { "WorkflowStepId", "Order" });
+
+            migrationBuilder.AddForeignKey(
+                name: "FK_ContractDepartmentApprovals_WorkflowStepInnerSteps_InnerStepId",
+                table: "ContractDepartmentApprovals",
+                column: "InnerStepId",
+                principalTable: "WorkflowStepInnerSteps",
+                principalColumn: "Id",
+                onDelete: ReferentialAction.Restrict);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropForeignKey(
+                name: "FK_ContractDepartmentApprovals_WorkflowStepInnerSteps_InnerStepId",
+                table: "ContractDepartmentApprovals");
+
+            migrationBuilder.DropTable(
+                name: "WorkflowStepInnerSteps");
+
+            migrationBuilder.DropIndex(
+                name: "IX_ContractDepartmentApprovals_InnerStepId",
+                table: "ContractDepartmentApprovals");
+
+            migrationBuilder.DropIndex(
+                name: "UX_ContractDeptApprovals_Contract_Phase_Dept_Stage",
+                table: "ContractDepartmentApprovals");
+
+            migrationBuilder.DropIndex(
+                name: "UX_ContractDeptApprovals_Contract_Phase_InnerStep",
+                table: "ContractDepartmentApprovals");
+
+            migrationBuilder.DropColumn(
+                name: "InnerStepId",
+                table: "ContractDepartmentApprovals");
+
+            migrationBuilder.CreateIndex(
+                name: "UX_ContractDeptApprovals_Contract_Phase_Dept_Stage",
+                table: "ContractDepartmentApprovals",
+                columns: new[] { "ContractId", "PhaseAtApproval", "DepartmentId", "Stage" },
+                unique: true);
+        }
+    }
+}

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

@@ -824,6 +824,9 @@ namespace SolutionErp.Infrastructure.Persistence.Migrations
                     b.Property<Guid>("DepartmentId")
                         .HasColumnType("uniqueidentifier");
 
+                    b.Property<Guid?>("InnerStepId")
+                        .HasColumnType("uniqueidentifier");
+
                     b.Property<bool>("IsBypassed")
                         .HasColumnType("bit");
 
@@ -850,9 +853,17 @@ namespace SolutionErp.Infrastructure.Persistence.Migrations
 
                     b.HasIndex("DepartmentId");
 
+                    b.HasIndex("InnerStepId");
+
+                    b.HasIndex("ContractId", "PhaseAtApproval", "InnerStepId")
+                        .IsUnique()
+                        .HasDatabaseName("UX_ContractDeptApprovals_Contract_Phase_InnerStep")
+                        .HasFilter("[InnerStepId] IS NOT NULL");
+
                     b.HasIndex("ContractId", "PhaseAtApproval", "DepartmentId", "Stage")
                         .IsUnique()
-                        .HasDatabaseName("UX_ContractDeptApprovals_Contract_Phase_Dept_Stage");
+                        .HasDatabaseName("UX_ContractDeptApprovals_Contract_Phase_Dept_Stage")
+                        .HasFilter("[InnerStepId] IS NULL");
 
                     b.ToTable("ContractDepartmentApprovals", (string)null);
                 });
@@ -1477,6 +1488,55 @@ namespace SolutionErp.Infrastructure.Persistence.Migrations
                     b.ToTable("WorkflowStepApprovers", (string)null);
                 });
 
+            modelBuilder.Entity("SolutionErp.Domain.Contracts.WorkflowStepInnerStep", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("uniqueidentifier");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("datetime2");
+
+                    b.Property<Guid?>("CreatedBy")
+                        .HasColumnType("uniqueidentifier");
+
+                    b.Property<Guid>("DepartmentId")
+                        .HasColumnType("uniqueidentifier");
+
+                    b.Property<bool>("IsRequired")
+                        .HasColumnType("bit");
+
+                    b.Property<string>("Name")
+                        .HasMaxLength(200)
+                        .HasColumnType("nvarchar(200)");
+
+                    b.Property<int>("Order")
+                        .HasColumnType("int");
+
+                    b.Property<int>("PositionLevel")
+                        .HasColumnType("int");
+
+                    b.Property<int?>("SlaDays")
+                        .HasColumnType("int");
+
+                    b.Property<DateTime?>("UpdatedAt")
+                        .HasColumnType("datetime2");
+
+                    b.Property<Guid?>("UpdatedBy")
+                        .HasColumnType("uniqueidentifier");
+
+                    b.Property<Guid>("WorkflowStepId")
+                        .HasColumnType("uniqueidentifier");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("DepartmentId");
+
+                    b.HasIndex("WorkflowStepId", "Order");
+
+                    b.ToTable("WorkflowStepInnerSteps", (string)null);
+                });
+
             modelBuilder.Entity("SolutionErp.Domain.Contracts.WorkflowTypeAssignment", b =>
                 {
                     b.Property<Guid>("Id")
@@ -3282,6 +3342,11 @@ namespace SolutionErp.Infrastructure.Persistence.Migrations
                         .OnDelete(DeleteBehavior.Cascade)
                         .IsRequired();
 
+                    b.HasOne("SolutionErp.Domain.Contracts.WorkflowStepInnerStep", null)
+                        .WithMany()
+                        .HasForeignKey("InnerStepId")
+                        .OnDelete(DeleteBehavior.Restrict);
+
                     b.Navigation("Contract");
                 });
 
@@ -3384,6 +3449,23 @@ namespace SolutionErp.Infrastructure.Persistence.Migrations
                     b.Navigation("Step");
                 });
 
+            modelBuilder.Entity("SolutionErp.Domain.Contracts.WorkflowStepInnerStep", b =>
+                {
+                    b.HasOne("SolutionErp.Domain.Master.Department", null)
+                        .WithMany()
+                        .HasForeignKey("DepartmentId")
+                        .OnDelete(DeleteBehavior.Restrict)
+                        .IsRequired();
+
+                    b.HasOne("SolutionErp.Domain.Contracts.WorkflowStep", "Step")
+                        .WithMany("InnerSteps")
+                        .HasForeignKey("WorkflowStepId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.Navigation("Step");
+                });
+
             modelBuilder.Entity("SolutionErp.Domain.Identity.MenuItem", b =>
                 {
                     b.HasOne("SolutionErp.Domain.Identity.MenuItem", "Parent")
@@ -3611,6 +3693,8 @@ namespace SolutionErp.Infrastructure.Persistence.Migrations
             modelBuilder.Entity("SolutionErp.Domain.Contracts.WorkflowStep", b =>
                 {
                     b.Navigation("Approvers");
+
+                    b.Navigation("InnerSteps");
                 });
 
             modelBuilder.Entity("SolutionErp.Domain.Identity.MenuItem", b =>