diff --git a/SimpleAdmin.Application/Services/Onboarding/Audit/OnboardingAuditService.cs b/SimpleAdmin.Application/Services/Onboarding/Audit/OnboardingAuditService.cs
index 29606fa..2db0711 100644
--- a/SimpleAdmin.Application/Services/Onboarding/Audit/OnboardingAuditService.cs
+++ b/SimpleAdmin.Application/Services/Onboarding/Audit/OnboardingAuditService.cs
@@ -1,4 +1,4 @@
-namespace SimpleAdmin.Application;
+namespace SimpleAdmin.Application;
 
 /// <summary>
 /// 实现入职任务审核与退回业务能力。
@@ -28,6 +28,11 @@ public class OnboardingAuditService : IOnboardingAuditService
     /// 审核通过入职任务，并在同一事务中创建正式员工档案。
     /// </summary>
     public async Task Approve(OnboardingAuditActionInput input)
+    {
+        await OnboardingConcurrency.RunTask(_db, input.TaskId, () => ApproveCore(input), protectIdentity: true);
+    }
+
+    private async Task ApproveCore(OnboardingAuditActionInput input)
     {
         var task = await GetAuditableTask(input.TaskId);
         var employeeInfo = await _db.Queryable<ObTaskEmployeeInfo>()
@@ -150,6 +155,11 @@ public class OnboardingAuditService : IOnboardingAuditService
     /// 退回入职任务，保存审核意见并允许候选人补充资料。
     /// </summary>
     public async Task Reject(OnboardingAuditActionInput input)
+    {
+        await OnboardingConcurrency.RunTask(_db, input.TaskId, () => RejectCore(input));
+    }
+
+    private async Task RejectCore(OnboardingAuditActionInput input)
     {
         if (string.IsNullOrWhiteSpace(input.AuditOpinion))
         {
diff --git a/SimpleAdmin.Application/Services/Onboarding/Common/OnboardingConcurrency.cs b/SimpleAdmin.Application/Services/Onboarding/Common/OnboardingConcurrency.cs
new file mode 100644
index 0000000..6bb7179
--- /dev/null
+++ b/SimpleAdmin.Application/Services/Onboarding/Common/OnboardingConcurrency.cs
@@ -0,0 +1,169 @@
+using System.Data.Common;
+using System.Security.Cryptography;
+using System.Text;
+
+namespace SimpleAdmin.Application;
+
+/// <summary>
+/// 所有修改同一任务的入口共用 MySQL 命名锁，适用于同一主库上的多个后端实例。
+/// 锁使用独立、非池化连接，不在第三方请求期间持有业务数据库事务。
+/// </summary>
+internal static class OnboardingConcurrency
+{
+    public static Task RunTask(SqlSugarScope db, long taskId, Func<Task> action,
+        bool transactional = false, bool protectIdentity = false)
+        => RunTask(db, taskId, async () => { await action(); return true; },
+            transactional, protectIdentity);
+
+    public static Task<T> RunTask<T>(SqlSugarScope db, long taskId, Func<Task<T>> action,
+        bool transactional = false, bool protectIdentity = false)
+        => Run(db, $"task:{taskId}", () => protectIdentity
+            ? RunPerson(db, taskId, () => InTransaction(db, action, transactional))
+            : InTransaction(db, action, transactional));
+
+    public static Task RunEmployee(SqlSugarScope db, long employeeId, Func<Task> action)
+        => Run(db, $"employee:{employeeId}", async () => { await action(); return true; });
+
+    public static Task RunPublic(SqlSugarScope db, string token, Func<Task> action,
+        bool transactional = false, bool protectIdentity = false)
+        => RunPublic(db, token, async () => { await action(); return true; },
+            transactional, protectIdentity);
+
+    public static async Task<T> RunPublic<T>(SqlSugarScope db, string token, Func<Task<T>> action,
+        bool transactional = false, bool protectIdentity = false)
+    {
+        if (string.IsNullOrWhiteSpace(token))
+            throw Oops.Bah("入职链接 Token 不能为空");
+        var hash = Convert.ToHexString(SHA256.HashData(Encoding.UTF8.GetBytes(token)));
+        var link = await db.Queryable<ObTaskLink>().FirstAsync(item => item.TokenHash == hash)
+                   ?? throw Oops.Bah("链接不存在");
+        // 此处只定位锁；被保护的方法必须在锁内重新检查链接、任务状态和归属。
+        return await RunTask(db, link.TaskId, action, transactional, protectIdentity);
+    }
+
+    public static Task RunContract(SqlSugarScope db, long contractId, Func<Task> action,
+        bool transactional = false)
+        => RunContract(db, contractId, async () => { await action(); return true; }, transactional);
+
+    public static async Task<T> RunContract<T>(SqlSugarScope db, long contractId, Func<Task<T>> action,
+        bool transactional = false)
+    {
+        var contract = await db.Queryable<ObTaskContract>().InSingleAsync(contractId)
+                       ?? throw Oops.Bah("任务合同不存在");
+        return await RunTask(db, contract.TaskId, action, transactional);
+    }
+
+    public static async Task RunMaterial(SqlSugarScope db, long materialId, Func<Task> action)
+    {
+        var material = await db.Queryable<ObTaskMaterial>().InSingleAsync(materialId)
+                       ?? throw Oops.Bah("任务资料不存在");
+        await RunTask(db, material.TaskId, action, transactional: true);
+    }
+
+    private static async Task<T> RunPerson<T>(SqlSugarScope db, long taskId, Func<Task<T>> action)
+    {
+        var info = await db.Queryable<ObTaskEmployeeInfo>().FirstAsync(item => item.TaskId == taskId)
+                   ?? throw Oops.Bah("请先完整填写基本信息");
+        // 统一顺序：任务 -> 身份证 -> 手机；跨任务提交/建档的查重与写入也串行。
+        return await Run(db, "identity:" + info.IdCardNumber?.Trim().ToUpperInvariant(),
+            () => Run(db, "phone:" + info.Phone?.Trim(), action));
+    }
+
+    private static async Task<T> InTransaction<T>(SqlSugarScope db, Func<Task<T>> action, bool enabled)
+    {
+        if (!enabled || db.Ado.Transaction != null)
+            return await action();
+        await db.Ado.BeginTranAsync();
+        try
+        {
+            var result = await action();
+            await db.Ado.CommitTranAsync();
+            return result;
+        }
+        catch
+        {
+            await db.Ado.RollbackTranAsync();
+            throw;
+        }
+    }
+
+    private static Task<T> Run<T>(SqlSugarScope db, string resource, Func<Task<T>> action)
+    {
+        if (db.CurrentConnectionConfig.DbType != global::SqlSugar.DbType.MySql)
+            throw Oops.Bah("入职并发保护需要 MySQL 数据库");
+        // 使用已选择的业务主库，不能在只读副本/不同主库上分别申请锁。
+        var database = db.Ado.Connection.Database;
+        var key = Convert.ToHexString(SHA256.HashData(
+            Encoding.UTF8.GetBytes($"onboardx:{database}:{resource}")));
+        return OnboardingOperationGate.Run(key, () => Acquire(db, key), action);
+    }
+
+    private static async Task<IAsyncDisposable> Acquire(SqlSugarScope db, string key)
+    {
+        var connection = (DbConnection)Activator.CreateInstance(db.Ado.Connection.GetType());
+        var builder = new DbConnectionStringBuilder
+        {
+            ConnectionString = db.CurrentConnectionConfig.ConnectionString
+        };
+        // 确保异常关闭时会真正关闭持锁会话，不把命名锁留在连接池里。
+        builder["Pooling"] = false;
+        connection.ConnectionString = builder.ConnectionString;
+        try
+        {
+            await connection.OpenAsync();
+            await using var command = connection.CreateCommand();
+            command.CommandText = "SELECT GET_LOCK(@lockName, 0)";
+            command.CommandTimeout = 5;
+            AddKey(command, key);
+            var result = await command.ExecuteScalarAsync();
+            if (result == null || result == DBNull.Value || Convert.ToInt32(result) != 1)
+                throw Oops.Bah("当前数据正在处理，请稍后刷新重试");
+            return new NamedLock(connection, key);
+        }
+        catch
+        {
+            await connection.DisposeAsync();
+            throw;
+        }
+    }
+
+    private static void AddKey(DbCommand command, string key)
+    {
+        var parameter = command.CreateParameter();
+        parameter.ParameterName = "@lockName";
+        parameter.Value = key;
+        command.Parameters.Add(parameter);
+    }
+
+    private sealed class NamedLock : IAsyncDisposable
+    {
+        private readonly DbConnection _connection;
+        private readonly string _key;
+
+        public NamedLock(DbConnection connection, string key)
+        {
+            _connection = connection;
+            _key = key;
+        }
+
+        public async ValueTask DisposeAsync()
+        {
+            try
+            {
+                await using var command = _connection.CreateCommand();
+                command.CommandText = "SELECT RELEASE_LOCK(@lockName)";
+                command.CommandTimeout = 5;
+                AddKey(command, _key);
+                await command.ExecuteScalarAsync();
+            }
+            catch
+            {
+                // 非池化物理连接关闭会释放会话锁；释放错误不覆盖业务原异常。
+            }
+            finally
+            {
+                await _connection.DisposeAsync();
+            }
+        }
+    }
+}
diff --git a/SimpleAdmin.Application/Services/Onboarding/Common/OnboardingOperationGate.cs b/SimpleAdmin.Application/Services/Onboarding/Common/OnboardingOperationGate.cs
new file mode 100644
index 0000000..aaae251
--- /dev/null
+++ b/SimpleAdmin.Application/Services/Onboarding/Common/OnboardingOperationGate.cs
@@ -0,0 +1,35 @@
+using System.Threading;
+
+namespace SimpleAdmin.Application;
+
+/// <summary>
+/// 使同一异步调用链可重入，独立请求仍须取得外部互斥锁。
+/// 不在 Acquire 中设置 AsyncLocal，避免值不能流回调用方的问题。
+/// </summary>
+internal static class OnboardingOperationGate
+{
+    private sealed record Frame(string Key, Frame Parent);
+    private static readonly AsyncLocal<Frame> Held = new();
+
+    internal static async Task<T> Run<T>(
+        string key,
+        Func<Task<IAsyncDisposable>> acquire,
+        Func<Task<T>> action)
+    {
+        for (var frame = Held.Value; frame != null; frame = frame.Parent)
+            if (frame.Key == key)
+                return await action();
+
+        await using var lease = await acquire();
+        var previous = Held.Value;
+        Held.Value = new Frame(key, previous);
+        try
+        {
+            return await action();
+        }
+        finally
+        {
+            Held.Value = previous;
+        }
+    }
+}
diff --git a/SimpleAdmin.Application/Services/Onboarding/Company/OnboardingCompanyService.cs b/SimpleAdmin.Application/Services/Onboarding/Company/OnboardingCompanyService.cs
index e54ebd3..518835e 100644
--- a/SimpleAdmin.Application/Services/Onboarding/Company/OnboardingCompanyService.cs
+++ b/SimpleAdmin.Application/Services/Onboarding/Company/OnboardingCompanyService.cs
@@ -21,7 +21,7 @@ public class OnboardingCompanyService : DbRepository<ObCompany>, IOnboardingComp
             .WhereIF(!string.IsNullOrWhiteSpace(input.CompanyCode), it => it.CompanyCode.Contains(input.CompanyCode))
             .WhereIF(!string.IsNullOrWhiteSpace(input.CompanyName), it => it.CompanyName.Contains(input.CompanyName))
             .WhereIF(!string.IsNullOrWhiteSpace(input.Status), it => it.Status == input.Status)
-            .OrderByIF(!string.IsNullOrWhiteSpace(input.SortField), $"{input.SortField} {input.SortOrder}")
+            .OrderByIF(!string.IsNullOrWhiteSpace(input.SortField), input.GetSafeOrderBy("Id", "Status", "CreateTime", "UpdateTime", "CreateUser", "CreateUserId", "CompanyCode", "CompanyName", "LegalName", "ContactPhone"))
             .OrderBy(it => it.CreateTime)
             .ToPagedListAsync(input.PageNum, input.PageSize);
     }
diff --git a/SimpleAdmin.Application/Services/Onboarding/ContractDocument/OnboardingContractDocumentService.cs b/SimpleAdmin.Application/Services/Onboarding/ContractDocument/OnboardingContractDocumentService.cs
index 66fbf6c..3ef15f3 100644
--- a/SimpleAdmin.Application/Services/Onboarding/ContractDocument/OnboardingContractDocumentService.cs
+++ b/SimpleAdmin.Application/Services/Onboarding/ContractDocument/OnboardingContractDocumentService.cs
@@ -297,6 +297,11 @@ public class OnboardingContractDocumentService : IOnboardingContractDocumentServ
     /// 根据锁定的模板版本和任务变量快照生成已替换变量的合同 DOCX。
     /// </summary>
     public async Task<long> Generate(OnboardingGenerateContractInput input)
+    {
+        return await OnboardingConcurrency.RunContract(_db, input.TaskContractId, () => GenerateCore(input));
+    }
+
+    private async Task<long> GenerateCore(OnboardingGenerateContractInput input)
     {
         var contract = await _db.Queryable<ObTaskContract>().InSingleAsync(input.TaskContractId)
             ?? throw Oops.Bah("任务合同不存在");
@@ -312,6 +317,11 @@ public class OnboardingContractDocumentService : IOnboardingContractDocumentServ
 
     /// <inheritdoc />
     public async Task<long> GenerateForPublicAccess(long taskContractId, long taskId)
+    {
+        return await OnboardingConcurrency.RunTask(_db, taskId, () => GenerateForPublicAccessCore(taskContractId, taskId));
+    }
+
+    private async Task<long> GenerateForPublicAccessCore(long taskContractId, long taskId)
     {
         var contract = await _db.Queryable<ObTaskContract>()
             .FirstAsync(item => item.Id == taskContractId && item.TaskId == taskId)
diff --git a/SimpleAdmin.Application/Services/Onboarding/ContractSnapshot/OnboardingContractSnapshotService.cs b/SimpleAdmin.Application/Services/Onboarding/ContractSnapshot/OnboardingContractSnapshotService.cs
index 2e532d5..6045625 100644
--- a/SimpleAdmin.Application/Services/Onboarding/ContractSnapshot/OnboardingContractSnapshotService.cs
+++ b/SimpleAdmin.Application/Services/Onboarding/ContractSnapshot/OnboardingContractSnapshotService.cs
@@ -19,6 +19,14 @@ public class OnboardingContractSnapshotService : IOnboardingContractSnapshotServ
         long taskId,
         ObTaskEmployeeInfo employeeInfo = null,
         bool invalidateGeneratedPreview = false)
+    {
+        await OnboardingConcurrency.RunTask(_db, taskId, () => BuildCore(taskId, employeeInfo, invalidateGeneratedPreview), transactional: true);
+    }
+
+    private async Task BuildCore(
+        long taskId,
+        ObTaskEmployeeInfo employeeInfo = null,
+        bool invalidateGeneratedPreview = false)
     {
         var task = await _db.Queryable<ObOnboardingTask>().InSingleAsync(taskId)
             ?? throw Oops.Bah("入职任务不存在");
diff --git a/SimpleAdmin.Application/Services/Onboarding/ContractTemplate/OnboardingContractTemplateService.cs b/SimpleAdmin.Application/Services/Onboarding/ContractTemplate/OnboardingContractTemplateService.cs
index 6ebde40..a73e131 100644
--- a/SimpleAdmin.Application/Services/Onboarding/ContractTemplate/OnboardingContractTemplateService.cs
+++ b/SimpleAdmin.Application/Services/Onboarding/ContractTemplate/OnboardingContractTemplateService.cs
@@ -40,7 +40,7 @@ public class OnboardingContractTemplateService : DbRepository<ObContractTemplate
         }
 
         var page = await query
-            .OrderByIF(!string.IsNullOrWhiteSpace(input.SortField), $"{input.SortField} {input.SortOrder}")
+            .OrderByIF(!string.IsNullOrWhiteSpace(input.SortField), input.GetSafeOrderBy("Id", "Status", "CreateTime", "UpdateTime", "CreateUser", "CreateUserId", "CompanyId", "DepartmentId", "TemplateCode", "TemplateName", "ContractType"))
             .OrderByDescending(it => it.CreateTime)
             .OrderBy(it => it.TemplateName)
             .ToPagedListAsync(input.PageNum, input.PageSize);
diff --git a/SimpleAdmin.Application/Services/Onboarding/Department/OnboardingDepartmentService.cs b/SimpleAdmin.Application/Services/Onboarding/Department/OnboardingDepartmentService.cs
index 5701d06..2c30cfb 100644
--- a/SimpleAdmin.Application/Services/Onboarding/Department/OnboardingDepartmentService.cs
+++ b/SimpleAdmin.Application/Services/Onboarding/Department/OnboardingDepartmentService.cs
@@ -1,4 +1,4 @@
-namespace SimpleAdmin.Application;
+namespace SimpleAdmin.Application;
 
 /// <summary>
 /// 实现入职业务部门业务能力。
@@ -22,7 +22,7 @@ public class OnboardingDepartmentService : DbRepository<ObDepartment>, IOnboardi
             .WhereIF(!string.IsNullOrWhiteSpace(input.DepartmentCode), it => it.DepartmentCode.Contains(input.DepartmentCode))
             .WhereIF(!string.IsNullOrWhiteSpace(input.DepartmentName), it => it.DepartmentName.Contains(input.DepartmentName))
             .WhereIF(!string.IsNullOrWhiteSpace(input.Status), it => it.Status == input.Status)
-            .OrderByIF(!string.IsNullOrWhiteSpace(input.SortField), $"{input.SortField} {input.SortOrder}")
+            .OrderByIF(!string.IsNullOrWhiteSpace(input.SortField), input.GetSafeOrderBy("Id", "Status", "CreateTime", "UpdateTime", "CreateUser", "CreateUserId", "CompanyId", "DepartmentCode", "DepartmentName", "SortCode"))
             .OrderBy(it => it.SortCode)
             .OrderBy(it => it.DepartmentName)
             .ToPagedListAsync(input.PageNum, input.PageSize);
diff --git a/SimpleAdmin.Application/Services/Onboarding/ElectronicSign/OnboardingElectronicSignService.cs b/SimpleAdmin.Application/Services/Onboarding/ElectronicSign/OnboardingElectronicSignService.cs
index d696ce1..cfa408c 100644
--- a/SimpleAdmin.Application/Services/Onboarding/ElectronicSign/OnboardingElectronicSignService.cs
+++ b/SimpleAdmin.Application/Services/Onboarding/ElectronicSign/OnboardingElectronicSignService.cs
@@ -48,6 +48,12 @@ public class OnboardingElectronicSignService : IOnboardingElectronicSignService
     /// <inheritdoc />
     public async Task<OnboardingElectronicSignDetailOutput> Initiate(
         OnboardingElectronicSignTaskInput input)
+    {
+        return await OnboardingConcurrency.RunTask(_db, input.TaskId, () => InitiateCore(input));
+    }
+
+    private async Task<OnboardingElectronicSignDetailOutput> InitiateCore(
+        OnboardingElectronicSignTaskInput input)
     {
         var task = await GetAuthorizedTask(input.TaskId);
         ValidateTaskCanSign(task);
@@ -99,6 +105,12 @@ public class OnboardingElectronicSignService : IOnboardingElectronicSignService
     /// <inheritdoc />
     public async Task<OnboardingElectronicSignDetailOutput> Reinitiate(
         OnboardingElectronicSignReinitiateInput input)
+    {
+        return await OnboardingConcurrency.RunTask(_db, input.TaskId, () => ReinitiateCore(input));
+    }
+
+    private async Task<OnboardingElectronicSignDetailOutput> ReinitiateCore(
+        OnboardingElectronicSignReinitiateInput input)
     {
         var task = await GetAuthorizedTask(input.TaskId);
         ValidateTaskCanSign(task);
@@ -256,6 +268,12 @@ public class OnboardingElectronicSignService : IOnboardingElectronicSignService
     /// <inheritdoc />
     public async Task<OnboardingElectronicSignDetailOutput> Sync(
         OnboardingElectronicSignTaskInput input)
+    {
+        return await OnboardingConcurrency.RunTask(_db, input.TaskId, () => SyncCore(input));
+    }
+
+    private async Task<OnboardingElectronicSignDetailOutput> SyncCore(
+        OnboardingElectronicSignTaskInput input)
     {
         var task = await GetAuthorizedTask(input.TaskId);
         var process = await GetRequiredProcess(task.Id);
@@ -266,6 +284,12 @@ public class OnboardingElectronicSignService : IOnboardingElectronicSignService
     /// <inheritdoc />
     public async Task<OnboardingElectronicSignDetailOutput> GetSignLink(
         OnboardingElectronicSignTaskInput input)
+    {
+        return await OnboardingConcurrency.RunTask(_db, input.TaskId, () => GetSignLinkCore(input));
+    }
+
+    private async Task<OnboardingElectronicSignDetailOutput> GetSignLinkCore(
+        OnboardingElectronicSignTaskInput input)
     {
         var task = await GetAuthorizedTask(input.TaskId);
         var process = await GetRequiredProcess(task.Id);
@@ -289,6 +313,12 @@ public class OnboardingElectronicSignService : IOnboardingElectronicSignService
     /// <inheritdoc />
     public async Task<OnboardingElectronicSignPreviewOutput> PreviewEmployeeSignedDocument(
         OnboardingElectronicSignPreviewInput input)
+    {
+        return await OnboardingConcurrency.RunTask(_db, input.TaskId, () => PreviewEmployeeSignedDocumentCore(input));
+    }
+
+    private async Task<OnboardingElectronicSignPreviewOutput> PreviewEmployeeSignedDocumentCore(
+        OnboardingElectronicSignPreviewInput input)
     {
         var task = await GetTask(input.TaskId);
         var process = await GetRequiredProcess(task.Id);
@@ -346,6 +376,12 @@ public class OnboardingElectronicSignService : IOnboardingElectronicSignService
     /// <inheritdoc />
     public async Task<OnboardingElectronicSignDetailOutput> CompanySeal(
         OnboardingElectronicSignTaskInput input)
+    {
+        return await OnboardingConcurrency.RunTask(_db, input.TaskId, () => CompanySealCore(input));
+    }
+
+    private async Task<OnboardingElectronicSignDetailOutput> CompanySealCore(
+        OnboardingElectronicSignTaskInput input)
     {
         var task = await GetAuthorizedTask(input.TaskId);
         var process = await GetRequiredProcess(task.Id);
@@ -378,7 +414,29 @@ public class OnboardingElectronicSignService : IOnboardingElectronicSignService
                 $"请先逐份查看员工已签文件：{string.Join("、", notPreviewed)}");
         }
 
+        // 发出前持久化占用。进程退出/响应丢失也不能自动重发可能已送达的盖章命令。
+        var alreadySubmitted = await _db.Queryable<ObElectronicSignEvent>()
+            .AnyAsync(item => item.SignProcessId == process.Id
+                             && item.EventSource == AdminCompanySealEventSource
+                             && (item.EventType == "company_seal_submitted"
+                                 || item.EventType == "company_seal_dispatch_started"));
+        if (alreadySubmitted)
+            throw Oops.Bah("企业盖章命令已发送或结果待确认，请先刷新签署状态并核实契约锁平台，系统不会重复盖章");
+
         var companyName = await GetCompanyLegalName(task);
+        await RecordAdminOperation(
+            process,
+            AdminCompanySealEventSource,
+            "company_seal_dispatch_started",
+            JsonSerializer.Serialize(new
+            {
+                process.ProviderContractId,
+                companyName,
+                process.SealId,
+                operatorUserId = UserManager.UserId,
+                operatorName = UserManager.Name
+            }),
+            "已占用盖章请求；发送结果待确认，禁止自动重复发送");
         try
         {
             await _qiyuesuoClient.CompanySign(
@@ -406,10 +464,10 @@ public class OnboardingElectronicSignService : IOnboardingElectronicSignService
                 return await BuildDetail(task, process);
             }
 
-            process.LastError = $"企业盖章失败：{LimitError(signException.Message)}";
+            process.LastError = $"企业盖章结果待核实，已阻止重复发送：{LimitError(signException.Message)}";
             process.UpdateTime = DateTime.Now;
             await _db.Updateable(process).ExecuteCommandAsync();
-            throw;
+            throw Oops.Bah("企业盖章未确认成功，请刷新状态并核实契约锁平台；为避免重复盖章，不能直接重发。原因：" + LimitError(signException.Message));
         }
 
         await RecordAdminOperation(
@@ -441,6 +499,11 @@ public class OnboardingElectronicSignService : IOnboardingElectronicSignService
 
     /// <inheritdoc />
     public async Task Notice(OnboardingElectronicSignTaskInput input)
+    {
+        await OnboardingConcurrency.RunTask(_db, input.TaskId, () => NoticeCore(input));
+    }
+
+    private async Task NoticeCore(OnboardingElectronicSignTaskInput input)
     {
         var task = await GetAuthorizedTask(input.TaskId);
         var process = await GetRequiredProcess(task.Id);
@@ -455,6 +518,11 @@ public class OnboardingElectronicSignService : IOnboardingElectronicSignService
 
     /// <inheritdoc />
     public async Task Invalid(OnboardingElectronicSignInvalidInput input)
+    {
+        await OnboardingConcurrency.RunTask(_db, input.TaskId, () => InvalidCore(input));
+    }
+
+    private async Task InvalidCore(OnboardingElectronicSignInvalidInput input)
     {
         var task = await GetAuthorizedTask(input.TaskId);
         var process = await GetRequiredProcess(task.Id);
@@ -478,6 +546,21 @@ public class OnboardingElectronicSignService : IOnboardingElectronicSignService
 
     /// <inheritdoc />
     public async Task HandleCallback(string payloadJson)
+    {
+        if (string.IsNullOrWhiteSpace(payloadJson))
+            throw Oops.Bah("契约锁回调内容为空");
+        using var json = JsonDocument.Parse(payloadJson);
+        var process = await FindProcess(FindString(json.RootElement, "contractId"), FindString(json.RootElement, "bizId"));
+        if (process == null)
+        {
+            await HandleCallbackCore(payloadJson);
+            return;
+        }
+        // 只在锁外定位任务；锁内重新读取事件和流程，重复回调不会同时执行归档。
+        await OnboardingConcurrency.RunTask(_db, process.TaskId, () => HandleCallbackCore(payloadJson, taskLockHeld: true));
+    }
+
+    private async Task HandleCallbackCore(string payloadJson, bool taskLockHeld = false)
     {
         if (string.IsNullOrWhiteSpace(payloadJson))
             throw Oops.Bah("契约锁回调内容为空");
@@ -504,6 +587,13 @@ public class OnboardingElectronicSignService : IOnboardingElectronicSignService
             "contractStatus",
             "status");
         var process = await FindProcess(providerContractId, bizId);
+        // 回调首次定位时流程可能还在创建；若此刻才匹配到，先取得任务锁再重新执行。
+        if (process != null && !taskLockHeld)
+        {
+            await OnboardingConcurrency.RunTask(_db, process.TaskId,
+                () => HandleCallbackCore(payloadJson, taskLockHeld: true));
+            return;
+        }
         if (callbackEvent == null)
         {
             callbackEvent = new ObElectronicSignEvent
@@ -549,7 +639,7 @@ public class OnboardingElectronicSignService : IOnboardingElectronicSignService
         try
         {
             process.LastCallbackAt = DateTime.Now;
-            await _db.Updateable(process).ExecuteCommandAsync();
+            await _db.Updateable(process).UpdateColumns(item => item.LastCallbackAt).ExecuteCommandAsync();
             // 明文回调只作为刷新触发器，最终状态重新向契约锁查询，伪造回调不能改变业务状态。
             await SyncProcess(process, "callback");
             callbackEvent.ProviderStatus = process.ProviderStatus;
@@ -939,7 +1029,7 @@ public class OnboardingElectronicSignService : IOnboardingElectronicSignService
         ObElectronicSignProcess process,
         QiyuesuoContractResult providerContract)
     {
-        var localStatus = ResolveSignStatus(providerContract);
+        var localStatus = OnboardingSignStateGuard.Resolve(process.SignStatus, ResolveSignStatus(providerContract));
         process.ProviderStatus = providerContract.Status;
         process.SignStatus = localStatus;
         if (localStatus == ElectronicSignStatus.Completed
@@ -950,7 +1040,8 @@ public class OnboardingElectronicSignService : IOnboardingElectronicSignService
             process.SignUrlExpireAt = null;
             await _db.Updateable<ObTaskContract>()
                 .SetColumns(item => item.ContractStatus == TaskContractStatus.ElectronicSigned)
-                .Where(item => item.TaskId == process.TaskId)
+                .Where(item => item.TaskId == process.TaskId && process.IsCurrent == true
+                               && item.ContractStatus != TaskContractStatus.Archived)
                 .ExecuteCommandAsync();
         }
         else if (IsTerminal(localStatus))
@@ -974,24 +1065,25 @@ public class OnboardingElectronicSignService : IOnboardingElectronicSignService
 
         foreach (var document in documents)
         {
-            if (document.SignedPdfFileId.HasValue)
-                continue;
-            var signedPdf = await _qiyuesuoClient.DownloadDocument(
-                document.ProviderDocumentId);
-            var pdfFileId = await _fileService.StoreGeneratedFile(
-                SysDictConst.FILE_ENGINE_ALIYUN_OSS,
-                $"{SafeFileName(process.BizId)}_{document.DocumentSort:D2}_{SafeFileName(document.DocumentName)}_已签署.pdf",
-                signedPdf);
-            document.SignedPdfFileId = pdfFileId;
-            document.UpdateTime = DateTime.Now;
-            await _db.Updateable(document).ExecuteCommandAsync();
+            if (!document.SignedPdfFileId.HasValue)
+            {
+                var signedPdf = await _qiyuesuoClient.DownloadDocument(document.ProviderDocumentId);
+                document.SignedPdfFileId = await _fileService.StoreGeneratedFile(
+                    SysDictConst.FILE_ENGINE_ALIYUN_OSS,
+                    $"{SafeFileName(process.BizId)}_{document.DocumentSort:D2}_{SafeFileName(document.DocumentName)}_已签署.pdf",
+                    signedPdf);
+                document.UpdateTime = DateTime.Now;
+                await _db.Updateable(document).ExecuteCommandAsync();
+            }
+            // 中断重试时仍回填合同指针，不能因文档已落库而跳过未完成的关联更新。
+            var pdfFileId = document.SignedPdfFileId.Value;
             await _db.Updateable<ObTaskContract>()
                 .SetColumns(item => new ObTaskContract
                 {
                     GeneratedPdfFileId = pdfFileId,
                     ContractStatus = TaskContractStatus.Archived
                 })
-                .Where(item => item.Id == document.TaskContractId)
+                .Where(item => item.Id == document.TaskContractId && process.IsCurrent == true)
                 .ExecuteCommandAsync();
         }
 
diff --git a/SimpleAdmin.Application/Services/Onboarding/ElectronicSign/OnboardingSignStateGuard.cs b/SimpleAdmin.Application/Services/Onboarding/ElectronicSign/OnboardingSignStateGuard.cs
new file mode 100644
index 0000000..f1b967b
--- /dev/null
+++ b/SimpleAdmin.Application/Services/Onboarding/ElectronicSign/OnboardingSignStateGuard.cs
@@ -0,0 +1,23 @@
+namespace SimpleAdmin.Application;
+
+/// <summary>同步第三方状态时的单向迁移保护；未知/陈旧结果不能覆盖已确认的签署进度。</summary>
+internal static class OnboardingSignStateGuard
+{
+    internal static string Resolve(string current, string incoming)
+    {
+        if (current == ElectronicSignStatus.Archived && incoming == ElectronicSignStatus.Completed)
+            return ElectronicSignStatus.Archived;
+        if (IsTerminal(current) && current != incoming)
+            throw Oops.Bah("契约锁返回状态与本地终态不一致，已保留本地状态，请核实后重试");
+        if (current == ElectronicSignStatus.PendingCompanySeal
+            && incoming is not (ElectronicSignStatus.PendingCompanySeal
+                or ElectronicSignStatus.Completed or ElectronicSignStatus.Archived
+                or ElectronicSignStatus.Rejected or ElectronicSignStatus.Invalid or ElectronicSignStatus.Expired))
+            throw Oops.Bah("契约锁状态暂未同步，已保留员工签署结果，请稍后重试");
+        return incoming;
+    }
+
+    private static bool IsTerminal(string status)
+        => status is ElectronicSignStatus.Completed or ElectronicSignStatus.Archived
+            or ElectronicSignStatus.Rejected or ElectronicSignStatus.Invalid or ElectronicSignStatus.Expired;
+}
diff --git a/SimpleAdmin.Application/Services/Onboarding/Employee/OnboardingEmployeeService.cs b/SimpleAdmin.Application/Services/Onboarding/Employee/OnboardingEmployeeService.cs
index 5cd6d66..ea2e11f 100644
--- a/SimpleAdmin.Application/Services/Onboarding/Employee/OnboardingEmployeeService.cs
+++ b/SimpleAdmin.Application/Services/Onboarding/Employee/OnboardingEmployeeService.cs
@@ -10,6 +10,7 @@ namespace SimpleAdmin.Application;
 /// </summary>
 public class OnboardingEmployeeService : IOnboardingEmployeeService
 {
+    private const string EmployeeExportTemplateFileName = "员工导出模版.xlsx";
     private readonly SqlSugarScope _db;
     private readonly IOnboardingDataPermissionService _dataPermission;
 
@@ -110,12 +111,17 @@ public class OnboardingEmployeeService : IOnboardingEmployeeService
             };
         }).ToList();
 
-        using var package = new ExcelPackage();
+        var templatePath = ResolveEmployeeExportTemplatePath();
+        using var package = new ExcelPackage(new FileInfo(templatePath));
         package.Workbook.Properties.Title = "员工明细";
         package.Workbook.Properties.Subject = "员工基本、人事状态及主要合同信息";
         package.Workbook.Properties.Created = DateTime.Now;
 
-        WriteEmployeeSheet(package.Workbook.Worksheets.Add("员工明细"), employeeRows);
+        var worksheet = package.Workbook.Worksheets.FirstOrDefault(item =>
+                            item.Dimension != null
+                            && string.Equals(item.Cells[1, 1].Text.Trim(), "姓名", StringComparison.OrdinalIgnoreCase))
+                        ?? throw Oops.Bah("员工导出模板未找到以“姓名”开头的表头行，请检查模板内容");
+        WriteEmployeeSheet(worksheet, employeeRows);
 
         return new OnboardingEmployeeExportFile
         {
@@ -192,6 +198,11 @@ public class OnboardingEmployeeService : IOnboardingEmployeeService
 
     /// <inheritdoc />
     public async Task UpdateHrInfo(OnboardingEmployeeHrUpdateInput input)
+    {
+        await OnboardingConcurrency.RunEmployee(_db, input.Id, () => UpdateHrInfoCore(input));
+    }
+
+    private async Task UpdateHrInfoCore(OnboardingEmployeeHrUpdateInput input)
     {
         ValidateEmploymentType(input.EmploymentType);
         ValidateSocialInsuranceStatus(input.SocialInsuranceStatus);
@@ -275,6 +286,11 @@ public class OnboardingEmployeeService : IOnboardingEmployeeService
 
     /// <inheritdoc />
     public async Task Regularize(OnboardingEmployeeRegularizeInput input)
+    {
+        await OnboardingConcurrency.RunEmployee(_db, input.Id, () => RegularizeCore(input));
+    }
+
+    private async Task RegularizeCore(OnboardingEmployeeRegularizeInput input)
     {
         if (!input.RegularizationDate.HasValue)
             throw Oops.Bah("请选择转正日期");
@@ -370,6 +386,11 @@ public class OnboardingEmployeeService : IOnboardingEmployeeService
 
     /// <inheritdoc />
     public async Task RevokeRegularization(OnboardingEmployeeRegularizationRevokeInput input)
+    {
+        await OnboardingConcurrency.RunEmployee(_db, input.Id, () => RevokeRegularizationCore(input));
+    }
+
+    private async Task RevokeRegularizationCore(OnboardingEmployeeRegularizationRevokeInput input)
     {
         if (string.IsNullOrWhiteSpace(input.Remark))
             throw Oops.Bah("请填写撤销原因");
@@ -775,7 +796,100 @@ public class OnboardingEmployeeService : IOnboardingEmployeeService
             TextColumn("工资卡开户行", row => row.Employee.BankName, 22)
         };
 
-        WriteWorksheet(worksheet, columns, rows);
+        WriteEmployeeTemplateWorksheet(worksheet, columns, rows);
+    }
+
+    private static void WriteEmployeeTemplateWorksheet(
+        ExcelWorksheet worksheet,
+        IReadOnlyList<ExportColumn<EmployeeExportContext>> columns,
+        IReadOnlyList<EmployeeExportContext> rows)
+    {
+        var templateColumnCount = worksheet.Dimension?.End.Column ?? 0;
+        if (templateColumnCount == 0)
+            throw Oops.Bah("员工导出模板没有配置表头");
+
+        var columnsByHeader = columns.ToDictionary(
+            item => item.Header,
+            item => item,
+            StringComparer.OrdinalIgnoreCase);
+        var headerAliases = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
+        {
+            ["户口所在地"] = "户籍所在地"
+        };
+        var templateColumns = new List<(int Index, ExportColumn<EmployeeExportContext> Column)>();
+        var mappedHeaders = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
+
+        for (var columnIndex = 1; columnIndex <= templateColumnCount; columnIndex++)
+        {
+            var templateHeader = worksheet.Cells[1, columnIndex].Text?.Trim();
+            if (string.IsNullOrWhiteSpace(templateHeader))
+                throw Oops.Bah($"员工导出模板第 {columnIndex} 列表头为空，请补充后重新导出");
+
+            var exportHeader = headerAliases.GetValueOrDefault(templateHeader, templateHeader);
+            if (!columnsByHeader.TryGetValue(exportHeader, out var exportColumn))
+                throw Oops.Bah($"员工导出模板包含无法识别的表头“{templateHeader}”，请检查模板");
+            if (!mappedHeaders.Add(exportHeader))
+                throw Oops.Bah($"员工导出模板表头“{templateHeader}”重复，请检查模板");
+
+            templateColumns.Add((columnIndex, exportColumn));
+        }
+
+        var missingHeaders = columns
+            .Where(item => !mappedHeaders.Contains(item.Header))
+            .Select(item => item.Header)
+            .ToList();
+        if (missingHeaders.Count > 0)
+            throw Oops.Bah($"员工导出模板缺少表头：{string.Join("、", missingHeaders)}");
+
+        var existingLastRow = worksheet.Dimension?.End.Row ?? 1;
+        for (var rowIndex = 2; rowIndex <= existingLastRow; rowIndex++)
+        {
+            for (var columnIndex = 1; columnIndex <= templateColumnCount; columnIndex++)
+                worksheet.Cells[rowIndex, columnIndex].Value = null;
+        }
+
+        for (var rowIndex = 0; rowIndex < rows.Count; rowIndex++)
+        {
+            var excelRow = rowIndex + 2;
+            foreach (var templateColumn in templateColumns)
+            {
+                var cell = worksheet.Cells[excelRow, templateColumn.Index];
+                var value = templateColumn.Column.Value(rows[rowIndex]);
+                if (value != null)
+                    cell.Value = value;
+
+                var templateNumberFormat = worksheet.Cells[1, templateColumn.Index]
+                    .Style.Numberformat.Format;
+                cell.Style.Numberformat.Format = string.IsNullOrWhiteSpace(templateNumberFormat)
+                                                || string.Equals(
+                                                    templateNumberFormat,
+                                                    "General",
+                                                    StringComparison.OrdinalIgnoreCase)
+                    ? templateColumn.Column.NumberFormat
+                    : templateNumberFormat;
+            }
+        }
+    }
+
+    private static string ResolveEmployeeExportTemplatePath()
+    {
+        var currentDirectory = Directory.GetCurrentDirectory();
+        var candidates = new[]
+        {
+            Path.Combine(AppContext.BaseDirectory, "Upload", EmployeeExportTemplateFileName),
+            Path.Combine(currentDirectory, "Upload", EmployeeExportTemplateFileName),
+            Path.Combine(currentDirectory, "SimpleAdmin.Web.Core", "Upload", EmployeeExportTemplateFileName),
+            Path.GetFullPath(Path.Combine(
+                currentDirectory,
+                "..",
+                "SimpleAdmin.Web.Core",
+                "Upload",
+                EmployeeExportTemplateFileName))
+        };
+
+        var templatePath = candidates.FirstOrDefault(File.Exists);
+        return templatePath
+               ?? throw Oops.Bah("员工导出模板文件不存在，请检查部署目录中的 Upload/员工导出模版.xlsx");
     }
 
     private static void WriteContractSheet(
diff --git a/SimpleAdmin.Application/Services/Onboarding/Lifecycle/OnboardingTaskLifecycleService.cs b/SimpleAdmin.Application/Services/Onboarding/Lifecycle/OnboardingTaskLifecycleService.cs
index 1a19244..fd85a2d 100644
--- a/SimpleAdmin.Application/Services/Onboarding/Lifecycle/OnboardingTaskLifecycleService.cs
+++ b/SimpleAdmin.Application/Services/Onboarding/Lifecycle/OnboardingTaskLifecycleService.cs
@@ -18,6 +18,11 @@ public class OnboardingTaskLifecycleService : IOnboardingTaskLifecycleService
     /// 归档已审核通过的入职任务。
     /// </summary>
     public async Task Archive(OnboardingAuditActionInput input)
+    {
+        await OnboardingConcurrency.RunTask(_db, input.TaskId, () => ArchiveCore(input));
+    }
+
+    private async Task ArchiveCore(OnboardingAuditActionInput input)
     {
         var task = await Authorize(input.TaskId);
         if (task.TaskStatus != OnboardingTaskStatus.Approved)
@@ -57,6 +62,11 @@ public class OnboardingTaskLifecycleService : IOnboardingTaskLifecycleService
     /// 撤销入职任务并同步撤销仍然有效的员工填写链接。
     /// </summary>
     public async Task Revoke(OnboardingAuditActionInput input)
+    {
+        await OnboardingConcurrency.RunTask(_db, input.TaskId, () => RevokeCore(input));
+    }
+
+    private async Task RevokeCore(OnboardingAuditActionInput input)
     {
         var task = await Authorize(input.TaskId);
         if (task.TaskStatus == OnboardingTaskStatus.Approved
@@ -102,6 +112,11 @@ public class OnboardingTaskLifecycleService : IOnboardingTaskLifecycleService
     /// 删除已撤销的入职任务及其全部关联快照数据。
     /// </summary>
     public async Task Delete(BaseIdInput input)
+    {
+        await OnboardingConcurrency.RunTask(_db, input.Id, () => DeleteCore(input));
+    }
+
+    private async Task DeleteCore(BaseIdInput input)
     {
         var task = await Authorize(input.Id);
         if (task.TaskStatus != OnboardingTaskStatus.Revoked)
diff --git a/SimpleAdmin.Application/Services/Onboarding/MaterialReview/OnboardingMaterialReviewService.cs b/SimpleAdmin.Application/Services/Onboarding/MaterialReview/OnboardingMaterialReviewService.cs
index cc03113..5a94669 100644
--- a/SimpleAdmin.Application/Services/Onboarding/MaterialReview/OnboardingMaterialReviewService.cs
+++ b/SimpleAdmin.Application/Services/Onboarding/MaterialReview/OnboardingMaterialReviewService.cs
@@ -22,6 +22,11 @@ public class OnboardingMaterialReviewService : IOnboardingMaterialReviewService
     /// 审核单份候选人上传材料并记录审核意见。
     /// </summary>
     public async Task Review(OnboardingMaterialReviewInput input)
+    {
+        await OnboardingConcurrency.RunMaterial(_db, input.TaskMaterialId, () => ReviewCore(input));
+    }
+
+    private async Task ReviewCore(OnboardingMaterialReviewInput input)
     {
         if (input.ReviewStatus != TaskMaterialReviewStatus.Passed
             && input.ReviewStatus != TaskMaterialReviewStatus.NeedSupplement)
diff --git a/SimpleAdmin.Application/Services/Onboarding/Position/OnboardingPositionService.cs b/SimpleAdmin.Application/Services/Onboarding/Position/OnboardingPositionService.cs
index 69119f9..964ff1f 100644
--- a/SimpleAdmin.Application/Services/Onboarding/Position/OnboardingPositionService.cs
+++ b/SimpleAdmin.Application/Services/Onboarding/Position/OnboardingPositionService.cs
@@ -23,7 +23,7 @@ public class OnboardingPositionService : DbRepository<ObPosition>, IOnboardingPo
             .WhereIF(!string.IsNullOrWhiteSpace(input.PositionCode), it => it.PositionCode.Contains(input.PositionCode))
             .WhereIF(!string.IsNullOrWhiteSpace(input.PositionName), it => it.PositionName.Contains(input.PositionName))
             .WhereIF(!string.IsNullOrWhiteSpace(input.Status), it => it.Status == input.Status)
-            .OrderByIF(!string.IsNullOrWhiteSpace(input.SortField), $"{input.SortField} {input.SortOrder}")
+            .OrderByIF(!string.IsNullOrWhiteSpace(input.SortField), input.GetSafeOrderBy("Id", "Status", "CreateTime", "UpdateTime", "CreateUser", "CreateUserId", "CompanyId", "DepartmentId", "PositionCode", "PositionName"))
             .OrderByDescending(it => it.CreateTime)
             .OrderBy(it => it.PositionName)
             .ToPagedListAsync(input.PageNum, input.PageSize);
diff --git a/SimpleAdmin.Application/Services/Onboarding/PublicSubmission/OnboardingPublicSubmissionService.cs b/SimpleAdmin.Application/Services/Onboarding/PublicSubmission/OnboardingPublicSubmissionService.cs
index 54c442a..0fb0db1 100644
--- a/SimpleAdmin.Application/Services/Onboarding/PublicSubmission/OnboardingPublicSubmissionService.cs
+++ b/SimpleAdmin.Application/Services/Onboarding/PublicSubmission/OnboardingPublicSubmissionService.cs
@@ -25,6 +25,11 @@ public class OnboardingPublicSubmissionService : IOnboardingPublicSubmissionServ
     /// 关联已上传 OSS 文件与任务材料要求。
     /// </summary>
     public async Task SaveMaterial(OnboardingSaveMaterialInput input)
+    {
+        await OnboardingConcurrency.RunPublic(_db, input.Token, () => SaveMaterialCore(input), transactional: true);
+    }
+
+    private async Task SaveMaterialCore(OnboardingSaveMaterialInput input)
     {
         var task = await GetEditableTask(input.Token);
         var requirement = await _db.Queryable<ObTaskMaterialRequirement>()
@@ -84,6 +89,12 @@ public class OnboardingPublicSubmissionService : IOnboardingPublicSubmissionServ
     /// </summary>
     public async Task DeleteMaterial(
         OnboardingDeleteMaterialInput input)
+    {
+        await OnboardingConcurrency.RunPublic(_db, input.Token, () => DeleteMaterialCore(input), transactional: true);
+    }
+
+    private async Task DeleteMaterialCore(
+        OnboardingDeleteMaterialInput input)
     {
         var task = await GetEditableTask(input.Token);
         var material = await _db.Queryable<ObTaskMaterial>()
@@ -102,6 +113,11 @@ public class OnboardingPublicSubmissionService : IOnboardingPublicSubmissionServ
     /// 记录候选人已经查看并确认动态生成的合同。
     /// </summary>
     public async Task ConfirmContract(OnboardingConfirmContractInput input)
+    {
+        await OnboardingConcurrency.RunPublic(_db, input.Token, () => ConfirmContractCore(input), transactional: true);
+    }
+
+    private async Task ConfirmContractCore(OnboardingConfirmContractInput input)
     {
         var task = await GetEditableTask(input.Token);
         var contract = await _db.Queryable<ObTaskContract>()
@@ -119,6 +135,11 @@ public class OnboardingPublicSubmissionService : IOnboardingPublicSubmissionServ
     /// 校验固定信息、动态字段、材料、合同变量和合同确认后提交审核。
     /// </summary>
     public async Task Submit(OnboardingSubmitInput input)
+    {
+        await OnboardingConcurrency.RunPublic(_db, input.Token, () => SubmitCore(input), transactional: true, protectIdentity: true);
+    }
+
+    private async Task SubmitCore(OnboardingSubmitInput input)
     {
         var task = await GetEditableTask(input.Token);
         var info = await _db.Queryable<ObTaskEmployeeInfo>()
@@ -160,11 +181,19 @@ public class OnboardingPublicSubmissionService : IOnboardingPublicSubmissionServ
 
         var submittedAt = DateTime.Now;
         var identityConfirmationHash = BuildIdentityConfirmationHash(info);
+        var originalStatus = task.TaskStatus;
+        var originalSubmitCount = task.SubmitCount;
         task.TaskStatus = OnboardingTaskStatus.Reviewing;
         task.SubmitCount++;
         task.LastSubmittedAt = submittedAt;
         task.RejectReason = null;
-        await _db.Updateable(task).ExecuteCommandAsync();
+        var changed = await _db.Updateable(task)
+            .UpdateColumns(item => new { item.TaskStatus, item.SubmitCount, item.LastSubmittedAt, item.RejectReason })
+            .Where(item => item.Id == task.Id && item.TaskStatus == originalStatus
+                           && item.SubmitCount == originalSubmitCount)
+            .ExecuteCommandAsync();
+        if (changed != 1)
+            throw Oops.Bah("任务状态已变更，请刷新后重试");
 
         await _db.Insertable(new ObTaskAudit
         {
diff --git a/SimpleAdmin.Application/Services/Onboarding/PublicTask/OnboardingPublicTaskService.cs b/SimpleAdmin.Application/Services/Onboarding/PublicTask/OnboardingPublicTaskService.cs
index 9995f6c..df8b4ee 100644
--- a/SimpleAdmin.Application/Services/Onboarding/PublicTask/OnboardingPublicTaskService.cs
+++ b/SimpleAdmin.Application/Services/Onboarding/PublicTask/OnboardingPublicTaskService.cs
@@ -25,6 +25,11 @@ public class OnboardingPublicTaskService : IOnboardingPublicTaskService
     /// 通过有效 Token 获取任务创建时冻结的材料、合同和新版入职登记表信息。
     /// </summary>
     public async Task<OnboardingTaskPublicDetailOutput> Detail(OnboardingTaskPublicAccessInput input)
+    {
+        return await OnboardingConcurrency.RunPublic(_db, input.Token, () => DetailCore(input));
+    }
+
+    private async Task<OnboardingTaskPublicDetailOutput> DetailCore(OnboardingTaskPublicAccessInput input)
     {
         var link = await GetActiveLink(input.Token);
         var task = await _db.Queryable<ObOnboardingTask>().InSingleAsync(link.TaskId)
@@ -136,6 +141,11 @@ public class OnboardingPublicTaskService : IOnboardingPublicTaskService
     /// 保存候选人的固定基础信息并刷新尚未确认的合同变量快照。
     /// </summary>
     public async Task SaveEmployeeInfo(OnboardingTaskPublicSaveInput input)
+    {
+        await OnboardingConcurrency.RunPublic(_db, input.Token, () => SaveEmployeeInfoCore(input), transactional: true);
+    }
+
+    private async Task SaveEmployeeInfoCore(OnboardingTaskPublicSaveInput input)
     {
         var link = await GetActiveLink(input.Token);
         var task = await _db.Queryable<ObOnboardingTask>().InSingleAsync(link.TaskId)
@@ -192,6 +202,12 @@ public class OnboardingPublicTaskService : IOnboardingPublicTaskService
     /// </summary>
     public async Task<OnboardingPublicContractPrepareOutput> PrepareContract(
         OnboardingPublicContractSourceInput input)
+    {
+        return await OnboardingConcurrency.RunPublic(_db, input.Token, () => PrepareContractCore(input));
+    }
+
+    private async Task<OnboardingPublicContractPrepareOutput> PrepareContractCore(
+        OnboardingPublicContractSourceInput input)
     {
         var link = await GetActiveLink(input.Token);
         var contract = await _db.Queryable<ObTaskContract>()
@@ -233,6 +249,11 @@ public class OnboardingPublicTaskService : IOnboardingPublicTaskService
     /// 返回已经准备完成的合同文件，下载阶段不再执行变量校验和文档生成。
     /// </summary>
     public async Task<long> GetContractSourceFileId(OnboardingPublicContractSourceInput input)
+    {
+        return await OnboardingConcurrency.RunPublic(_db, input.Token, () => GetContractSourceFileIdCore(input));
+    }
+
+    private async Task<long> GetContractSourceFileIdCore(OnboardingPublicContractSourceInput input)
     {
         var link = await GetActiveLink(input.Token);
         var contract = await _db.Queryable<ObTaskContract>()
diff --git a/SimpleAdmin.Application/Services/Onboarding/TaskContractVariable/OnboardingTaskContractVariableService.cs b/SimpleAdmin.Application/Services/Onboarding/TaskContractVariable/OnboardingTaskContractVariableService.cs
index 97fdc6d..65a1e84 100644
--- a/SimpleAdmin.Application/Services/Onboarding/TaskContractVariable/OnboardingTaskContractVariableService.cs
+++ b/SimpleAdmin.Application/Services/Onboarding/TaskContractVariable/OnboardingTaskContractVariableService.cs
@@ -81,6 +81,11 @@ public class OnboardingTaskContractVariableService : IOnboardingTaskContractVari
     /// 保存允许人事编辑的任务合同变量值。
     /// </summary>
     public async Task Save(OnboardingTaskContractVariableSaveInput input)
+    {
+        await OnboardingConcurrency.RunContract(_db, input.TaskContractId, () => SaveCore(input), transactional: true);
+    }
+
+    private async Task SaveCore(OnboardingTaskContractVariableSaveInput input)
     {
         var contract = await _db.Queryable<ObTaskContract>()
             .InSingleAsync(input.TaskContractId)
diff --git a/SimpleAdmin.Application/Services/Onboarding/TaskQuery/OnboardingTaskQueryService.cs b/SimpleAdmin.Application/Services/Onboarding/TaskQuery/OnboardingTaskQueryService.cs
index 591f981..0dbb22b 100644
--- a/SimpleAdmin.Application/Services/Onboarding/TaskQuery/OnboardingTaskQueryService.cs
+++ b/SimpleAdmin.Application/Services/Onboarding/TaskQuery/OnboardingTaskQueryService.cs
@@ -157,6 +157,11 @@ public class OnboardingTaskQueryService : IOnboardingTaskQueryService
     /// 获取或重新生成任务有效填写链接。
     /// </summary>
     public async Task<OnboardingTaskCreatedOutput> GetTaskLink(BaseIdInput input)
+    {
+        return await OnboardingConcurrency.RunTask(_db, input.Id, () => GetTaskLinkCore(input));
+    }
+
+    private async Task<OnboardingTaskCreatedOutput> GetTaskLinkCore(BaseIdInput input)
     {
         var task = await _db.Queryable<ObOnboardingTask>().InSingleAsync(input.Id)
             ?? throw Oops.Bah("入职任务不存在");
diff --git a/SimpleAdmin.Core/BaseInput/BasePageInput.cs b/SimpleAdmin.Core/BaseInput/BasePageInput.cs
index 8eb2057..584dbdf 100644
--- a/SimpleAdmin.Core/BaseInput/BasePageInput.cs
+++ b/SimpleAdmin.Core/BaseInput/BasePageInput.cs
@@ -1,4 +1,4 @@
-// Copyright (c) 2022-Now 少林寺驻北固山办事处大神父王喇嘛
+// Copyright (c) 2022-Now 少林寺驻北固山办事处大神父王喇嘛
 // 
 // SimpleAdmin 基于 Apache License Version 2.0 协议发布，可用于商业项目，但必须遵守以下补充条款:
 // 1.请不要删除和修改根目录下的LICENSE文件。
@@ -45,26 +45,37 @@ public class BasePageInput : IValidatableObject
 
     public IEnumerable<ValidationResult> Validate(ValidationContext validationContext)
     {
-        //配合小诺排序参数
-        if (SortOrder == "descend")
+        SortOrder = (string.IsNullOrWhiteSpace(SortOrder) ? "desc" : SortOrder.Trim().ToLowerInvariant()) switch
         {
-            SortOrder = "desc";
-        }
-        else if (SortOrder == "ascend")
-        {
-            SortOrder = "asc";
-        }
-        if (!string.IsNullOrEmpty(SortField))
-        {
-            //分割排序字段
-            var fields = SortField.Split(" ");
-            if (fields.Length > 1)
-            {
-                yield return new ValidationResult("排序字段错误", new[]
-                {
-                    nameof(SortField)
-                });
-            }
-        }
+            "ascend" => "asc",
+            "descend" => "desc",
+            var value => value
+        };
+        if (SortOrder != "asc" && SortOrder != "desc")
+            yield return new ValidationResult("排序方向仅支持 asc/desc", new[] { nameof(SortOrder) });
+
+        if (!string.IsNullOrEmpty(SortField)
+            && !global::System.Text.RegularExpressions.Regex.IsMatch(
+                SortField, @"\A[A-Za-z_][A-Za-z0-9_]{0,63}\z"))
+            yield return new ValidationResult("排序字段格式不正确", new[] { nameof(SortField) });
     }
-}
+
+    /// <summary>
+    /// 将客户端字段映射为服务端白名单列，禁止把排序表达式传入 ORM。
+    /// 服务层再次校验，避免非 HTTP 调用绕过 MVC 参数校验。
+    /// </summary>
+    public string GetSafeOrderBy(params string[] allowedFields)
+    {
+        var error = Validate(new ValidationContext(this)).FirstOrDefault();
+        if (error != null)
+            throw Oops.Bah(error.ErrorMessage);
+        if (string.IsNullOrEmpty(SortField))
+            return string.Empty;
+        var field = allowedFields.FirstOrDefault(item =>
+            string.Equals(item, SortField, StringComparison.OrdinalIgnoreCase));
+        if (field == null)
+            throw Oops.Bah("不支持按此字段排序");
+        return $"{field} {SortOrder}";
+    }
+
+}
\ No newline at end of file
diff --git a/SimpleAdmin.System/Services/Dev/File/FileService.cs b/SimpleAdmin.System/Services/Dev/File/FileService.cs
index 1bffd96..9d15eb3 100644
--- a/SimpleAdmin.System/Services/Dev/File/FileService.cs
+++ b/SimpleAdmin.System/Services/Dev/File/FileService.cs
@@ -34,7 +34,7 @@ public class FileService : DbRepository<SysFile>, IFileService
     {
         var query = Context.Queryable<SysFile>().WhereIF(!string.IsNullOrEmpty(input.Engine), it => it.Engine == input.Engine)//根据关键字查询
             .WhereIF(!string.IsNullOrEmpty(input.SearchKey), it => it.Name.Contains(input.SearchKey))//根据关键字查询
-            .OrderByIF(!string.IsNullOrEmpty(input.SortField), $"{input.SortField} {input.SortOrder}")//排序
+            .OrderByIF(!string.IsNullOrEmpty(input.SortField), input.GetSafeOrderBy("Id", "Name", "Engine", "Bucket", "Suffix", "SizeKb", "SizeInfo", "CreateTime", "UpdateTime", "CreateUser"))//排序
             .OrderBy(it => it.Id);
         var pageInfo = await query.ToPagedListAsync(input.PageNum, input.PageSize);//分页
         return pageInfo;
diff --git a/SimpleAdmin.Web.Core/Upload/员工导出模版.xlsx b/SimpleAdmin.Web.Core/Upload/员工导出模版.xlsx
new file mode 100644
index 0000000..08b352c
Binary files /dev/null and b/SimpleAdmin.Web.Core/Upload/员工导出模版.xlsx differ
diff --git a/SimpleAdmin.Web.Entry/SimpleAdmin.Web.Entry.csproj b/SimpleAdmin.Web.Entry/SimpleAdmin.Web.Entry.csproj
index 51ac635..0b80a63 100644
--- a/SimpleAdmin.Web.Entry/SimpleAdmin.Web.Entry.csproj
+++ b/SimpleAdmin.Web.Entry/SimpleAdmin.Web.Entry.csproj
@@ -8,6 +8,11 @@
         <None Update="ip2region.db">
             <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
         </None>
+        <Content Include="..\SimpleAdmin.Web.Core\Upload\员工导出模版.xlsx">
+            <Link>Upload\员工导出模版.xlsx</Link>
+            <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
+            <CopyToPublishDirectory>PreserveNewest</CopyToPublishDirectory>
+        </Content>
     </ItemGroup>
     <ItemGroup>
         <ProjectReference Include="..\SimpleAdmin.Web.Core\SimpleAdmin.Web.Core.csproj" />
diff --git a/SimpleAdmin.Web.Entry/appsettings.json b/SimpleAdmin.Web.Entry/appsettings.json
index 87c6c64..f7d09ee 100644
--- a/SimpleAdmin.Web.Entry/appsettings.json
+++ b/SimpleAdmin.Web.Entry/appsettings.json
@@ -18,7 +18,7 @@
   
   //swagger设置
     "SpecificationDocumentSettings": {
-        "DocumentTitle": "未病局后台管理系统",
+        "DocumentTitle": "员工后台管理系统",
         "DocExpansionState": "None",
         "GroupOpenApiInfos": []
     },
diff --git a/tests/SecurityRegression/Program.cs b/tests/SecurityRegression/Program.cs
new file mode 100644
index 0000000..d47f56c
--- /dev/null
+++ b/tests/SecurityRegression/Program.cs
@@ -0,0 +1,90 @@
+using System.Collections.Concurrent;
+using SimpleAdmin.Core;
+using SimpleAdmin.Application;
+using SqlSugar;
+
+var passed = 0;
+void Check(bool condition, string name) {
+    if (!condition) throw new Exception("FAIL: " + name);
+    passed++;
+    Console.WriteLine("PASS: " + name);
+}
+void Reject(Action action, string name) {
+    try { action(); } catch (InvalidOperationException) { Check(true, name); return; }
+    throw new Exception("FAIL: expected rejection: " + name);
+}
+
+// Uses the real BasePageInput and real ORM SQL generation; never opens a DB connection.
+using var db = new SqlSugarClient(new ConnectionConfig {
+    ConnectionString = "Server=127.0.0.1;Database=never_connected;Uid=unused;Pwd=unused;",
+    DbType = SqlSugar.DbType.MySql, IsAutoCloseConnection = true
+});
+foreach (var order in new[] { "asc, CASE WHEN 1=1 THEN 0 ELSE 1 END", "desc;DROP TABLE x", "asc--", "asc\tLIMIT 1", "random()" })
+    Reject(() => new BasePageInput { SortField = "Id", SortOrder = order }.GetSafeOrderBy("Id"), "reject sort direction: " + order);
+foreach (var field in new[] { "Id,(CASE\tWHEN\t1=1\tTHEN\t0\tELSE\t1\tEND)", "Id\tDESC", "Id/**/", "Id;SELECT", "Id\n", "u.Id", "`Id`", "Id,Name", new string('a', 65) })
+    Reject(() => new BasePageInput { SortField = field }.GetSafeOrderBy("Id"), "reject sort field: " + field.Replace("\n", "<newline>"));
+Reject(() => new BasePageInput { SortField = "NotAllowed" }.GetSafeOrderBy("Id"), "column whitelist enforced");
+foreach (var sample in new[] { ("ascend", "asc"), ("descend", "desc"), (" ASC ", "asc"), ("", "desc"), ((string)null, "desc") }) {
+    var input = new BasePageInput { SortField = "id", SortOrder = sample.Item1 };
+    var orderBy = input.GetSafeOrderBy("Id", "Name");
+    Check(orderBy == "Id " + sample.Item2, "normalizes direction and maps column: " + sample.Item1);
+    var sql = db.Queryable<TestRow>().OrderBy(orderBy).ToSql().Key;
+    Check(sql.Contains("ORDER BY", StringComparison.OrdinalIgnoreCase) && !sql.Contains("CASE"), "safe ORM SQL generated");
+}
+Check(new BasePageInput().GetSafeOrderBy("Id") == "", "no requested sort preserves default");
+
+// Uses the real state guard and production status constants.
+Check(OnboardingSignStateGuard.Resolve(ElectronicSignStatus.PendingEmployeeSign, ElectronicSignStatus.PendingCompanySeal)
+    == ElectronicSignStatus.PendingCompanySeal, "employee signed -> company seal");
+Check(OnboardingSignStateGuard.Resolve(ElectronicSignStatus.PendingCompanySeal, ElectronicSignStatus.Completed)
+    == ElectronicSignStatus.Completed, "company seal -> completed");
+Check(OnboardingSignStateGuard.Resolve(ElectronicSignStatus.Archived, ElectronicSignStatus.Completed)
+    == ElectronicSignStatus.Archived, "completed provider result preserves local archive");
+foreach (var terminal in new[] { ElectronicSignStatus.Completed, ElectronicSignStatus.Archived, ElectronicSignStatus.Invalid, ElectronicSignStatus.Expired, ElectronicSignStatus.Rejected }) {
+    Check(OnboardingSignStateGuard.Resolve(terminal, terminal) == terminal, "terminal replay allowed: " + terminal);
+    Reject(() => OnboardingSignStateGuard.Resolve(terminal, ElectronicSignStatus.PendingEmployeeSign), "terminal rollback rejected: " + terminal);
+}
+foreach (var backward in new[] { ElectronicSignStatus.PendingEmployeeSign, ElectronicSignStatus.Draft, ElectronicSignStatus.Creating, ElectronicSignStatus.Failed })
+    Reject(() => OnboardingSignStateGuard.Resolve(ElectronicSignStatus.PendingCompanySeal, backward), "signed progress cannot regress: " + backward);
+
+// Exercises the real async gate with a fake external lease. Does NOT claim MySQL GET_LOCK integration.
+var leases = new FakeLeases();
+Task<int> Gate(string key, Func<Task<int>> action) => OnboardingOperationGate.Run(key, () => leases.Acquire(key), action);
+var entered = new TaskCompletionSource(TaskCreationOptions.RunContinuationsAsynchronously);
+var release = new TaskCompletionSource(TaskCreationOptions.RunContinuationsAsynchronously);
+var first = Gate("task:1", async () => { entered.SetResult(); await release.Task; return 1; });
+await entered.Task;
+var contenders = Enumerable.Range(0, 64).Select(async _ => {
+    try { await Gate("task:1", () => Task.FromResult(2)); return false; }
+    catch (InvalidOperationException) { return true; }
+}).ToArray();
+Check((await Task.WhenAll(contenders)).All(x => x), "64 independent same-task operations rejected while held");
+Check(await Gate("task:2", () => Task.FromResult(7)) == 7, "different tasks proceed independently");
+release.SetResult();
+await first;
+Check(await Gate("task:1", () => Task.FromResult(3)) == 3, "lock released after completion");
+var before = leases.AcquisitionCount;
+Check(await Gate("nested", () => Gate("nested", () => Gate("identity", () => Gate("nested", () => Task.FromResult(9))))) == 9,
+    "nested task/snapshot call is reentrant");
+Check(leases.AcquisitionCount - before == 2, "reentrant gate acquires each resource only once");
+try { await Gate("failure", () => throw new ApplicationException("synthetic fault")); } catch (ApplicationException) {}
+Check(await Gate("failure", () => Task.FromResult(4)) == 4, "lock released on exception");
+Check(leases.ActiveCount == 0, "no leaked leases or caller async context");
+Console.WriteLine("ALL " + passed + " CHECKS PASSED (offline; no business database or provider contacted)");
+
+[SugarTable("test_row")]
+public class TestRow { public long Id { get; set; } public string Name { get; set; } }
+public sealed class FakeLeases {
+    private readonly ConcurrentDictionary<string, byte> held = new();
+    private int acquisitions;
+    public int AcquisitionCount => acquisitions;
+    public int ActiveCount => held.Count;
+    public Task<IAsyncDisposable> Acquire(string key) {
+        if (!held.TryAdd(key, 0)) throw new InvalidOperationException("busy");
+        Interlocked.Increment(ref acquisitions);
+        return Task.FromResult<IAsyncDisposable>(new Lease(() => held.TryRemove(key, out _)));
+    }
+    private sealed class Lease(Action release) : IAsyncDisposable {
+        public ValueTask DisposeAsync() { release(); return ValueTask.CompletedTask; }
+    }
+}
diff --git a/tests/SecurityRegression/README.md b/tests/SecurityRegression/README.md
new file mode 100644
index 0000000..897220b
--- /dev/null
+++ b/tests/SecurityRegression/README.md
@@ -0,0 +1,34 @@
+# 第 2、5 项安全修复离线回归
+
+本测试直接链接生产代码的 BasePageInput、OnboardingOperationGate、OnboardingSignStateGuard 和状态常量。
+不启动业务程序、不连接业务数据库、不联系契约锁，也不查询在线漏洞库。
+SqlSugar 只生成 SQL。互斥测试使用模拟的外部租约，不代表 MySQL 集成测试。
+
+## 运行
+
+先在后端构建相应 net6.0 项目，确保 SimpleAdmin.Web.Entry/bin/Debug/net6.0 下已有 SqlSugar.dll 和 Newtonsoft.Json.dll。
+测试需要本机已安装 .NET 8 SDK/运行时。
+
+在后端目录执行：
+
+```powershell
+dotnet run --project tests/SecurityRegression/SecurityRegression.csproj -p:NuGetAudit=false -p:UseSharedCompilation=false
+```
+
+测试使用本地 empty-feed，不向外网发送依赖信息。无新增 NuGet 包。
+框架校验属性和友好异常由 Stubs.cs 替代；核心排序、异步重入和状态迁移逻辑直接引用源文件。
+
+## 覆盖
+
+- SQL 排序表达式、注释、分号、制表符、换行、未知字段被拒绝。
+- asc/desc/ascend/descend、大小写及空排序方向兼容。
+- 安全排序由本地 ORM 生成 SQL。
+- 签约终态、防回退、归档状态保持。
+- 64 个竞争调用与同任务互斥；不同任务互不阻塞。
+- 同调用链嵌套任务锁可重入；正常/异常结束释放锁；调用方上下文不泄漏。
+
+## 仍需测试环境验证
+
+MySQL GET_LOCK/RELEASE_LOCK 的多会话、多实例互斥、实际业务事务回滚、
+提交与审核/撤销竞争、转正与编辑竞争、重复/乱序契约锁回调、企业盖章网络断开及中断恢复。
+不得将这套离线用例当成真实平台压测或数据库集成测试结果。
diff --git a/tests/SecurityRegression/SecurityRegression.csproj b/tests/SecurityRegression/SecurityRegression.csproj
new file mode 100644
index 0000000..70324da
--- /dev/null
+++ b/tests/SecurityRegression/SecurityRegression.csproj
@@ -0,0 +1,15 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <TargetFrameworks></TargetFrameworks><OutputType>Exe</OutputType><TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings><NuGetAudit>false</NuGetAudit>
+    <RestoreSources>$(MSBuildThisFileDirectory)empty-feed</RestoreSources>
+  </PropertyGroup>
+  <ItemGroup>
+    <Reference Include="SqlSugar"><HintPath>../../SimpleAdmin.Web.Entry/bin/Debug/net6.0/SqlSugar.dll</HintPath></Reference>
+    <Reference Include="Newtonsoft.Json"><HintPath>../../SimpleAdmin.Web.Entry/bin/Debug/net6.0/Newtonsoft.Json.dll</HintPath></Reference>
+    <Compile Include="../../SimpleAdmin.Core/BaseInput/BasePageInput.cs" Link="BasePageInput.cs"/>
+    <Compile Include="../../SimpleAdmin.Application/Services/Onboarding/Common/OnboardingOperationGate.cs" Link="OnboardingOperationGate.cs"/>
+    <Compile Include="../../SimpleAdmin.Application/Services/Onboarding/ElectronicSign/OnboardingSignStateGuard.cs" Link="OnboardingSignStateGuard.cs"/>
+    <Compile Include="../../SimpleAdmin.Application/Entity/Onboarding/OnboardingStatus.cs" Link="OnboardingStatus.cs"/>
+  </ItemGroup>
+</Project>
\ No newline at end of file
diff --git a/tests/SecurityRegression/Stubs.cs b/tests/SecurityRegression/Stubs.cs
new file mode 100644
index 0000000..c0ffd50
--- /dev/null
+++ b/tests/SecurityRegression/Stubs.cs
@@ -0,0 +1,10 @@
+global using System.ComponentModel.DataAnnotations;
+namespace SimpleAdmin.Core {
+    [AttributeUsage(AttributeTargets.Property)]
+    public sealed class DataValidationAttribute : Attribute { public DataValidationAttribute(ValidationTypes type) {} }
+    public enum ValidationTypes { Numeric }
+    public static class Oops { public static Exception Bah(string text) => new InvalidOperationException(text); }
+}
+namespace SimpleAdmin.Application {
+    public static class Oops { public static Exception Bah(string text) => new InvalidOperationException(text); }
+}
diff --git a/tests/SecurityRegression/empty-feed/.gitkeep b/tests/SecurityRegression/empty-feed/.gitkeep
new file mode 100644
index 0000000..e69de29