排课计算、课表发布、补考自动编排三类任务统一接入消息系统。

业务任务与 Outbox 消息同一事务落库，避免“数据库成功但消息没发出去”。
RabbitMQ 使用持久化消息、发布确认、手动 ACK、Quorum Queue、死信队列。
增加处理租约、心跳、异常重试、最大重试次数和幂等状态控制。
保留 InMemory 模式，开发环境无需安装 RabbitMQ。
支持多实例竞争消费，后续可以横向扩容。
新增 /health/messaging 消息系统健康检查。

src/Jiaowu.Api/Infrastructure/Persistence/Migrations/MySql/20260726220000_BackgroundJobOutbox.cs

@@ -0,0 +1,62 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace Jiaowu.Api.Infrastructure.Persistence.Migrations.MySql
+{
+    /// <inheritdoc />
+    public partial class BackgroundJobOutbox : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "BackgroundJobOutboxMessages",
+                columns: table => new
+                {
+                    Id = table.Column<Guid>(type: "char(36)", nullable: false),
+                    JobKind = table.Column<int>(type: "int", nullable: false),
+                    JobId = table.Column<Guid>(type: "char(36)", nullable: false),
+                    State = table.Column<int>(type: "int", nullable: false),
+                    PublishAttempts = table.Column<int>(type: "int", nullable: false),
+                    ProcessingAttempts = table.Column<int>(type: "int", nullable: false),
+                    PublishedAt = table.Column<DateTime>(type: "datetime(6)", nullable: true),
+                    ProcessingToken = table.Column<Guid>(type: "char(36)", nullable: true),
+                    LeaseExpiresAt = table.Column<DateTime>(type: "datetime(6)", nullable: true),
+                    CompletedAt = table.Column<DateTime>(type: "datetime(6)", nullable: true),
+                    LastError = table.Column<string>(type: "varchar(2000)", maxLength: 2000, nullable: true),
+                    CreatedAt = table.Column<DateTime>(type: "datetime(6)", nullable: false),
+                    UpdatedAt = table.Column<DateTime>(type: "datetime(6)", nullable: false)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_BackgroundJobOutboxMessages", x => x.Id);
+                })
+                .Annotation("MySQL:Charset", "utf8mb4");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_BackgroundJobOutboxMessages_JobKind_JobId",
+                table: "BackgroundJobOutboxMessages",
+                columns: new[] { "JobKind", "JobId" },
+                unique: true);
+
+            migrationBuilder.CreateIndex(
+                name: "IX_BackgroundJobOutboxMessages_LeaseExpiresAt",
+                table: "BackgroundJobOutboxMessages",
+                column: "LeaseExpiresAt");
+
+            migrationBuilder.CreateIndex(
+                name: "IX_BackgroundJobOutboxMessages_State_CreatedAt",
+                table: "BackgroundJobOutboxMessages",
+                columns: new[] { "State", "CreatedAt" });
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "BackgroundJobOutboxMessages");
+        }
+    }
+}

src/Jiaowu.Api/Infrastructure/Persistence/Migrations/MySql/AppDbContextModelSnapshot.cs

@@ -3423,6 +3423,61 @@ namespace Jiaowu.Api.Infrastructure.Persistence.Migrations.MySql
                     b.ToTable("AuditLogs");
                 });
 
+            modelBuilder.Entity("Jiaowu.Api.Domain.System.BackgroundJobOutboxMessage", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("char(36)");
+
+                    b.Property<DateTime?>("CompletedAt")
+                        .HasColumnType("datetime(6)");
+
+                    b.Property<DateTime>("CreatedAt")
+                        .HasColumnType("datetime(6)");
+
+                    b.Property<Guid>("JobId")
+                        .HasColumnType("char(36)");
+
+                    b.Property<int>("JobKind")
+                        .HasColumnType("int");
+
+                    b.Property<string>("LastError")
+                        .HasMaxLength(2000)
+                        .HasColumnType("varchar(2000)");
+
+                    b.Property<DateTime?>("LeaseExpiresAt")
+                        .HasColumnType("datetime(6)");
+
+                    b.Property<int>("ProcessingAttempts")
+                        .HasColumnType("int");
+
+                    b.Property<Guid?>("ProcessingToken")
+                        .HasColumnType("char(36)");
+
+                    b.Property<int>("PublishAttempts")
+                        .HasColumnType("int");
+
+                    b.Property<DateTime?>("PublishedAt")
+                        .HasColumnType("datetime(6)");
+
+                    b.Property<int>("State")
+                        .HasColumnType("int");
+
+                    b.Property<DateTime>("UpdatedAt")
+                        .HasColumnType("datetime(6)");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("LeaseExpiresAt");
+
+                    b.HasIndex("JobKind", "JobId")
+                        .IsUnique();
+
+                    b.HasIndex("State", "CreatedAt");
+
+                    b.ToTable("BackgroundJobOutboxMessages");
+                });
+
             modelBuilder.Entity("Microsoft.AspNetCore.Identity.IdentityRoleClaim<System.Guid>", b =>
                 {
                     b.Property<int>("Id")