diff --git a/src/BuildFlow.Host/BuildFlowHostModule.cs b/src/BuildFlow.Host/BuildFlowHostModule.cs
index d8f1153..085c4cc 100644
--- a/src/BuildFlow.Host/BuildFlowHostModule.cs
+++ b/src/BuildFlow.Host/BuildFlowHostModule.cs
@@ -83,6 +83,9 @@ public class BuildFlowHostModule : AbpModule
 
         // 串联：IM @AI → RAG 问答（跨模块集成，RAG 实现 IAiBotHandler 供 IM 调用）
         services.AddScoped<BuildFlow.Shared.Integration.IAiBotHandler, BuildFlow.Application.Integration.AiBotHandler>();
+        // 串联：IM 离线消息 → 平台通知中心站内信（跨模块集成，Host 实现 IImNotificationPublisher 供 IM 调用，
+        // 内部转发为 PublishNotificationCommand 复用 platform 的 fanout 落库 + SignalR 推送）
+        services.AddScoped<IImNotificationPublisher, ImNotificationPublisher>();
         // 串联：AI 对话 → 触发工作流（跨模块集成，Workflow 实现 IWorkflowTriggerService 供 RAG 调用）
         services.AddScoped<BuildFlow.Shared.Integration.IWorkflowTriggerService, WorkflowTriggerService>();
 
diff --git a/src/BuildFlow.Host/Endpoints/file/Files/DeleteFileEndpoint.cs b/src/BuildFlow.Host/Endpoints/file/Files/DeleteFileEndpoint.cs
index 37c8c7b..8f3b42f 100644
--- a/src/BuildFlow.Host/Endpoints/file/Files/DeleteFileEndpoint.cs
+++ b/src/BuildFlow.Host/Endpoints/file/Files/DeleteFileEndpoint.cs
@@ -19,7 +19,7 @@ public class DeleteFileEndpoint(IMediator mediator) : Endpoint<DeleteFileRequest
 
     public override async Task HandleAsync(DeleteFileRequest req, CancellationToken ct)
     {
-        await mediator.Send(new DeleteFileCommand(req.BucketName, req.ObjectKey), ct);
+        await mediator.Send(new DeleteFileCommand(req.ObjectKey), ct);
         await Send.OkAsync(new { message = "deleted" }, ct);
     }
 }
diff --git a/src/BuildFlow.Host/Endpoints/file/Files/DeleteFileRequest.cs b/src/BuildFlow.Host/Endpoints/file/Files/DeleteFileRequest.cs
index 85c93cd..1f98a68 100644
--- a/src/BuildFlow.Host/Endpoints/file/Files/DeleteFileRequest.cs
+++ b/src/BuildFlow.Host/Endpoints/file/Files/DeleteFileRequest.cs
@@ -1,8 +1,7 @@
 namespace BuildFlow.Host.Endpoints.file.Files;
 
-/// <summary>删除文件请求。以查询参数指定存储桶与对象键。</summary>
+/// <summary>删除文件请求。以查询参数指定对象键。</summary>
 public class DeleteFileRequest
 {
-    [QueryParam] public string BucketName { get; init; } = default!;
     [QueryParam] public string ObjectKey { get; init; } = default!;
 }
diff --git a/src/BuildFlow.Host/Endpoints/file/Files/DownloadFileEndpoint.cs b/src/BuildFlow.Host/Endpoints/file/Files/DownloadFileEndpoint.cs
index 7d77b02..57ddf50 100644
--- a/src/BuildFlow.Host/Endpoints/file/Files/DownloadFileEndpoint.cs
+++ b/src/BuildFlow.Host/Endpoints/file/Files/DownloadFileEndpoint.cs
@@ -19,7 +19,7 @@ public class DownloadFileEndpoint(IMediator mediator) : Endpoint<DownloadFileReq
 
     public override async Task HandleAsync(DownloadFileRequest req, CancellationToken ct)
     {
-        var result = await mediator.Send(new DownloadFileQuery(req.BucketName, req.ObjectKey), ct);
+        var result = await mediator.Send(new DownloadFileQuery(req.ObjectKey), ct);
 
         // 设置响应头：真实 ContentType + 触发下载的文件名
         HttpContext.Response.StatusCode = 200;
diff --git a/src/BuildFlow.Host/Endpoints/file/Files/DownloadFileRequest.cs b/src/BuildFlow.Host/Endpoints/file/Files/DownloadFileRequest.cs
index e3801f4..ccc8f25 100644
--- a/src/BuildFlow.Host/Endpoints/file/Files/DownloadFileRequest.cs
+++ b/src/BuildFlow.Host/Endpoints/file/Files/DownloadFileRequest.cs
@@ -1,8 +1,7 @@
 namespace BuildFlow.Host.Endpoints.file.Files;
 
-/// <summary>下载文件请求。以查询参数指定存储桶与对象键。</summary>
+/// <summary>下载文件请求。以查询参数指定对象键。</summary>
 public class DownloadFileRequest
 {
-    [QueryParam] public string BucketName { get; init; } = default!;
     [QueryParam] public string ObjectKey { get; init; } = default!;
 }
diff --git a/src/BuildFlow.Host/Endpoints/file/Files/GetFileContentEndpoint.cs b/src/BuildFlow.Host/Endpoints/file/Files/GetFileContentEndpoint.cs
index 6399159..a4dd1eb 100644
--- a/src/BuildFlow.Host/Endpoints/file/Files/GetFileContentEndpoint.cs
+++ b/src/BuildFlow.Host/Endpoints/file/Files/GetFileContentEndpoint.cs
@@ -20,7 +20,7 @@ public class GetFileContentEndpoint(IMediator mediator) : Endpoint<GetFileConten
 
     public override async Task HandleAsync(GetFileContentRequest req, CancellationToken ct)
     {
-        var result = await mediator.Send(new GetFileContentQuery(req.BucketName, req.ObjectKey), ct);
+        var result = await mediator.Send(new GetFileContentQuery(req.ObjectKey), ct);
         await Send.OkAsync(result, ct);
     }
 }
diff --git a/src/BuildFlow.Host/Endpoints/file/Files/GetFileContentRequest.cs b/src/BuildFlow.Host/Endpoints/file/Files/GetFileContentRequest.cs
index 3a0aba0..c3ca190 100644
--- a/src/BuildFlow.Host/Endpoints/file/Files/GetFileContentRequest.cs
+++ b/src/BuildFlow.Host/Endpoints/file/Files/GetFileContentRequest.cs
@@ -1,8 +1,7 @@
 namespace BuildFlow.Host.Endpoints.file.Files;
 
-/// <summary>文件内容请求。以查询参数指定存储桶与对象键。</summary>
+/// <summary>文件内容请求。以查询参数指定对象键（bucket 由系统设置统一管理）。</summary>
 public class GetFileContentRequest
 {
-    [QueryParam] public string BucketName { get; init; } = default!;
     [QueryParam] public string ObjectKey { get; init; } = default!;
 }
diff --git a/src/BuildFlow.Host/Endpoints/file/Files/GetFilePreviewEndpoint.cs b/src/BuildFlow.Host/Endpoints/file/Files/GetFilePreviewEndpoint.cs
index 8a915c1..1d5f1d3 100644
--- a/src/BuildFlow.Host/Endpoints/file/Files/GetFilePreviewEndpoint.cs
+++ b/src/BuildFlow.Host/Endpoints/file/Files/GetFilePreviewEndpoint.cs
@@ -20,7 +20,7 @@ public class GetFilePreviewEndpoint(IMediator mediator) : Endpoint<GetFilePrevie
 
     public override async Task HandleAsync(GetFilePreviewRequest req, CancellationToken ct)
     {
-        var result = await mediator.Send(new GetFilePreviewQuery(req.BucketName, req.ObjectKey), ct);
+        var result = await mediator.Send(new GetFilePreviewQuery(req.ObjectKey), ct);
         await Send.OkAsync(result, ct);
     }
 }
diff --git a/src/BuildFlow.Host/Endpoints/file/Files/GetFilePreviewRequest.cs b/src/BuildFlow.Host/Endpoints/file/Files/GetFilePreviewRequest.cs
index 5125f61..3f3b087 100644
--- a/src/BuildFlow.Host/Endpoints/file/Files/GetFilePreviewRequest.cs
+++ b/src/BuildFlow.Host/Endpoints/file/Files/GetFilePreviewRequest.cs
@@ -1,8 +1,7 @@
 namespace BuildFlow.Host.Endpoints.file.Files;
 
-/// <summary>文件预览请求。以查询参数指定存储桶与对象键。</summary>
+/// <summary>文件预览请求。以查询参数指定对象键。</summary>
 public class GetFilePreviewRequest
 {
-    [QueryParam] public string BucketName { get; init; } = default!;
     [QueryParam] public string ObjectKey { get; init; } = default!;
 }
diff --git a/src/BuildFlow.Host/Endpoints/file/Files/GetOfficePreviewEndpoint.cs b/src/BuildFlow.Host/Endpoints/file/Files/GetOfficePreviewEndpoint.cs
index 02f16f0..d1edae6 100644
--- a/src/BuildFlow.Host/Endpoints/file/Files/GetOfficePreviewEndpoint.cs
+++ b/src/BuildFlow.Host/Endpoints/file/Files/GetOfficePreviewEndpoint.cs
@@ -22,7 +22,7 @@ public class GetOfficePreviewEndpoint(IMediator mediator) : Endpoint<GetOfficePr
 
     public override async Task HandleAsync(GetOfficePreviewRequest req, CancellationToken ct)
     {
-        var result = await mediator.Send(new GetOfficePreviewQuery(req.BucketName, req.ObjectKey), ct);
+        var result = await mediator.Send(new GetOfficePreviewQuery(req.ObjectKey), ct);
         await Send.OkAsync(result, ct);
     }
 }
diff --git a/src/BuildFlow.Host/Endpoints/file/Files/GetOfficePreviewRequest.cs b/src/BuildFlow.Host/Endpoints/file/Files/GetOfficePreviewRequest.cs
index 061dfdd..b3aae4b 100644
--- a/src/BuildFlow.Host/Endpoints/file/Files/GetOfficePreviewRequest.cs
+++ b/src/BuildFlow.Host/Endpoints/file/Files/GetOfficePreviewRequest.cs
@@ -1,8 +1,7 @@
 namespace BuildFlow.Host.Endpoints.file.Files;
 
-/// <summary>Office/PDF 文档预览请求。以查询参数指定存储桶与对象键。</summary>
+/// <summary>Office/PDF 文档预览请求。以查询参数指定对象键。</summary>
 public class GetOfficePreviewRequest
 {
-    [QueryParam] public string BucketName { get; init; } = default!;
     [QueryParam] public string ObjectKey { get; init; } = default!;
 }
diff --git a/src/BuildFlow.Host/Endpoints/file/Files/ListFilesEndpoint.cs b/src/BuildFlow.Host/Endpoints/file/Files/ListFilesEndpoint.cs
index cc165e3..32b2cab 100644
--- a/src/BuildFlow.Host/Endpoints/file/Files/ListFilesEndpoint.cs
+++ b/src/BuildFlow.Host/Endpoints/file/Files/ListFilesEndpoint.cs
@@ -20,7 +20,7 @@ public class ListFilesEndpoint(IMediator mediator) : Endpoint<ListFilesRequest,
 
     public override async Task HandleAsync(ListFilesRequest req, CancellationToken ct)
     {
-        var result = await mediator.Send(new ListFilesQuery(req.BucketName, req.Prefix, req.MaxKeys, req.ContinuationToken), ct);
+        var result = await mediator.Send(new ListFilesQuery(req.Prefix, req.MaxKeys, req.ContinuationToken), ct);
         await Send.OkAsync(result, ct);
     }
 }
diff --git a/src/BuildFlow.Host/Endpoints/file/Files/ListFilesRequest.cs b/src/BuildFlow.Host/Endpoints/file/Files/ListFilesRequest.cs
index 802223f..0d42f76 100644
--- a/src/BuildFlow.Host/Endpoints/file/Files/ListFilesRequest.cs
+++ b/src/BuildFlow.Host/Endpoints/file/Files/ListFilesRequest.cs
@@ -1,9 +1,8 @@
 namespace BuildFlow.Host.Endpoints.file.Files;
 
-/// <summary>列举文件请求。包含存储桶、前缀、最大键数与续传令牌。</summary>
+/// <summary>列举文件请求。包含前缀、最大键数与续传令牌。</summary>
 public class ListFilesRequest
 {
-    [QueryParam] public string BucketName { get; init; } = default!;
     [QueryParam] public string? Prefix { get; init; }
     [QueryParam] public int? MaxKeys { get; init; }
     [QueryParam] public string? ContinuationToken { get; init; }
diff --git a/src/BuildFlow.Host/Endpoints/file/Files/UploadFileEndpoint.cs b/src/BuildFlow.Host/Endpoints/file/Files/UploadFileEndpoint.cs
index 66bb06e..6aca954 100644
--- a/src/BuildFlow.Host/Endpoints/file/Files/UploadFileEndpoint.cs
+++ b/src/BuildFlow.Host/Endpoints/file/Files/UploadFileEndpoint.cs
@@ -22,7 +22,7 @@ public class UploadFileEndpoint(IMediator mediator) : Endpoint<UploadFileRequest
     public override async Task HandleAsync(UploadFileRequest req, CancellationToken ct)
     {
         await using var stream = req.File.OpenReadStream();
-        var result = await mediator.Send(new UploadFileCommand(req.BucketName, req.ObjectKey,
+        var result = await mediator.Send(new UploadFileCommand(req.ObjectKey,
             stream, req.File.ContentType, req.File.Length, req.ContentHash), ct);
         await Send.OkAsync(result, ct);
     }
diff --git a/src/BuildFlow.Host/Endpoints/file/Files/UploadFileRequest.cs b/src/BuildFlow.Host/Endpoints/file/Files/UploadFileRequest.cs
index 5fa0864..35495bb 100644
--- a/src/BuildFlow.Host/Endpoints/file/Files/UploadFileRequest.cs
+++ b/src/BuildFlow.Host/Endpoints/file/Files/UploadFileRequest.cs
@@ -1,9 +1,8 @@
 namespace BuildFlow.Host.Endpoints.file.Files;
 
-/// <summary>上传文件请求。包含 bucket_name、object_key 与文件数据。</summary>
+/// <summary>上传文件请求。包含 object_key 与文件数据。</summary>
 public class UploadFileRequest
 {
-    public string BucketName { get; init; } = default!;
     public string ObjectKey { get; init; } = default!;
     public IFormFile File { get; init; } = default!;
     /// <summary>文件内容哈希（可选），秒传查重用。</summary>
diff --git a/src/BuildFlow.Host/Endpoints/file/Multipart/AbortMultipartEndpoint.cs b/src/BuildFlow.Host/Endpoints/file/Multipart/AbortMultipartEndpoint.cs
index af0a391..1b2dbe4 100644
--- a/src/BuildFlow.Host/Endpoints/file/Multipart/AbortMultipartEndpoint.cs
+++ b/src/BuildFlow.Host/Endpoints/file/Multipart/AbortMultipartEndpoint.cs
@@ -19,7 +19,7 @@ public class AbortMultipartEndpoint(IMediator mediator) : Endpoint<AbortMultipar
 
     public override async Task HandleAsync(AbortMultipartRequest req, CancellationToken ct)
     {
-        await mediator.Send(new AbortMultipartCommand(req.BucketName, req.ObjectKey, req.UploadId), ct);
+        await mediator.Send(new AbortMultipartCommand(req.ObjectKey, req.UploadId), ct);
         await Send.OkAsync(new { message = "aborted" }, ct);
     }
 }
diff --git a/src/BuildFlow.Host/Endpoints/file/Multipart/AbortMultipartRequest.cs b/src/BuildFlow.Host/Endpoints/file/Multipart/AbortMultipartRequest.cs
index 0e364b1..ec8e516 100644
--- a/src/BuildFlow.Host/Endpoints/file/Multipart/AbortMultipartRequest.cs
+++ b/src/BuildFlow.Host/Endpoints/file/Multipart/AbortMultipartRequest.cs
@@ -1,9 +1,8 @@
 namespace BuildFlow.Host.Endpoints.file.Multipart;
 
-/// <summary>中止分片上传请求（桶、对象 key、UploadId）。</summary>
+/// <summary>中止分片上传请求（对象 key、UploadId）。</summary>
 public class AbortMultipartRequest
 {
-    public string BucketName { get; init; } = default!;
     public string ObjectKey { get; init; } = default!;
     public string UploadId { get; init; } = default!;
 }
diff --git a/src/BuildFlow.Host/Endpoints/file/Multipart/CompleteMultipartEndpoint.cs b/src/BuildFlow.Host/Endpoints/file/Multipart/CompleteMultipartEndpoint.cs
index 751e605..031e9fe 100644
--- a/src/BuildFlow.Host/Endpoints/file/Multipart/CompleteMultipartEndpoint.cs
+++ b/src/BuildFlow.Host/Endpoints/file/Multipart/CompleteMultipartEndpoint.cs
@@ -21,7 +21,7 @@ public class CompleteMultipartEndpoint(IMediator mediator) : Endpoint<CompleteMu
     public override async Task HandleAsync(CompleteMultipartRequest req, CancellationToken ct)
     {
         var parts = req.Parts.Select(p => new CompletedPartDto(p.PartNumber, p.ETag)).ToList();
-        var result = await mediator.Send(new CompleteMultipartCommand(req.BucketName, req.ObjectKey, req.UploadId, parts, req.FileName, req.Size), ct);
+        var result = await mediator.Send(new CompleteMultipartCommand(req.ObjectKey, req.UploadId, parts, req.FileName, req.Size), ct);
         await Send.OkAsync(result, ct);
     }
 }
diff --git a/src/BuildFlow.Host/Endpoints/file/Multipart/CompleteMultipartRequest.cs b/src/BuildFlow.Host/Endpoints/file/Multipart/CompleteMultipartRequest.cs
index 596b89a..3f42e90 100644
--- a/src/BuildFlow.Host/Endpoints/file/Multipart/CompleteMultipartRequest.cs
+++ b/src/BuildFlow.Host/Endpoints/file/Multipart/CompleteMultipartRequest.cs
@@ -3,7 +3,6 @@ namespace BuildFlow.Host.Endpoints.file.Multipart;
 /// <summary>完成分片上传请求（含各分片信息列表）。</summary>
 public class CompleteMultipartRequest
 {
-    public string BucketName { get; init; } = default!;
     public string ObjectKey { get; init; } = default!;
     public string UploadId { get; init; } = default!;
     public List<PartRequest> Parts { get; init; } = new();
diff --git a/src/BuildFlow.Host/Endpoints/file/Multipart/InitMultipartEndpoint.cs b/src/BuildFlow.Host/Endpoints/file/Multipart/InitMultipartEndpoint.cs
index 6e8a9b1..4b97e90 100644
--- a/src/BuildFlow.Host/Endpoints/file/Multipart/InitMultipartEndpoint.cs
+++ b/src/BuildFlow.Host/Endpoints/file/Multipart/InitMultipartEndpoint.cs
@@ -20,7 +20,7 @@ public class InitMultipartEndpoint(IMediator mediator) : Endpoint<InitMultipartR
 
     public override async Task HandleAsync(InitMultipartRequest req, CancellationToken ct)
     {
-        var result = await mediator.Send(new InitMultipartCommand(req.BucketName, req.ObjectKey, req.ContentHash, req.TotalParts, req.Size), ct);
+        var result = await mediator.Send(new InitMultipartCommand(req.ObjectKey, req.ContentHash, req.TotalParts, req.Size), ct);
         await Send.OkAsync(result, ct);
     }
 }
diff --git a/src/BuildFlow.Host/Endpoints/file/Multipart/InitMultipartRequest.cs b/src/BuildFlow.Host/Endpoints/file/Multipart/InitMultipartRequest.cs
index b53b507..eb2e7e4 100644
--- a/src/BuildFlow.Host/Endpoints/file/Multipart/InitMultipartRequest.cs
+++ b/src/BuildFlow.Host/Endpoints/file/Multipart/InitMultipartRequest.cs
@@ -3,8 +3,6 @@ namespace BuildFlow.Host.Endpoints.file.Multipart;
 /// <summary>初始化分片上传请求。ContentHash/TotalParts 可选，断点续传时由前端附带。</summary>
 public class InitMultipartRequest
 {
-    /// <summary>S3 存储桶名。</summary>
-    public string BucketName { get; init; } = default!;
     /// <summary>S3 对象 key（断点续传建议用内容哈希派生稳定值）。</summary>
     public string ObjectKey { get; init; } = default!;
     /// <summary>文件内容哈希（可选），仅落库记录用。</summary>
diff --git a/src/BuildFlow.Host/Endpoints/file/Multipart/UploadPartEndpoint.cs b/src/BuildFlow.Host/Endpoints/file/Multipart/UploadPartEndpoint.cs
index cfd8a28..80513d3 100644
--- a/src/BuildFlow.Host/Endpoints/file/Multipart/UploadPartEndpoint.cs
+++ b/src/BuildFlow.Host/Endpoints/file/Multipart/UploadPartEndpoint.cs
@@ -22,7 +22,7 @@ public class UploadPartEndpoint(IMediator mediator) : Endpoint<UploadPartRequest
     public override async Task HandleAsync(UploadPartRequest req, CancellationToken ct)
     {
         await using var stream = req.File.OpenReadStream();
-        var result = await mediator.Send(new UploadPartCommand(req.BucketName, req.ObjectKey,
+        var result = await mediator.Send(new UploadPartCommand(req.ObjectKey,
             req.UploadId, req.PartNumber, stream), ct);
         await Send.OkAsync(result, ct);
     }
diff --git a/src/BuildFlow.Host/Endpoints/file/Multipart/UploadPartRequest.cs b/src/BuildFlow.Host/Endpoints/file/Multipart/UploadPartRequest.cs
index b26f4cc..6a344c1 100644
--- a/src/BuildFlow.Host/Endpoints/file/Multipart/UploadPartRequest.cs
+++ b/src/BuildFlow.Host/Endpoints/file/Multipart/UploadPartRequest.cs
@@ -3,7 +3,6 @@ namespace BuildFlow.Host.Endpoints.file.Multipart;
 /// <summary>上传单个分片请求（含 multipart 文件流）。</summary>
 public class UploadPartRequest
 {
-    public string BucketName { get; init; } = default!;
     public string ObjectKey { get; init; } = default!;
     public string UploadId { get; init; } = default!;
     public int PartNumber { get; init; }
diff --git a/src/BuildFlow.Host/Services/Integration/ImNotificationPublisher.cs b/src/BuildFlow.Host/Services/Integration/ImNotificationPublisher.cs
new file mode 100644
index 0000000..6f764c1
--- /dev/null
+++ b/src/BuildFlow.Host/Services/Integration/ImNotificationPublisher.cs
@@ -0,0 +1,56 @@
+using IM.Domain.Common;
+using MediatR;
+using BuildFlow.Platform.Application.Notifications.Commands;
+
+namespace BuildFlow.Host.Services.Integration;
+
+/// <summary>
+/// IM 站内信通知发布器。把 IM 离线消息作为站内信投递到平台通知中心。
+/// </summary>
+/// <remarks>
+/// 跨模块胶水代码：IM 模块的 <see cref="SendMessageCommandHandler"/> 依赖
+/// <see cref="IImNotificationPublisher"/>（定义在 IM.Domain），但 IM 模块无法直接访问
+/// platform 模块的 Notification 聚合。本实现位于 Host 层，通过 MediatR 发送
+/// <see cref="PublishNotificationCommand"/>，复用 platform 已有的 fanout 落库 + SignalR 推送链路，
+/// 避免在 IM 侧重复实现通知持久化与分发。
+/// 容错：通知发布失败不阻断 IM 主链路——<see cref="SendMessageCommandHandler"/> 的调用方
+/// 已在注释中声明"通知失败不阻断主链路"，但本实现仍捕获异常并吞掉，确保即使 platform
+/// 通知链路异常也不会导致发消息接口报错。
+/// </remarks>
+public class ImNotificationPublisher(IMediator mediator) : IImNotificationPublisher
+{
+    /// <summary>
+    /// 批量发布站内信通知。内部转发为 <see cref="PublishNotificationCommand"/>，
+    /// 由 platform 的 <c>PublishNotificationCommandHandler</c> 完成 fanout 落库与 SignalR 推送。
+    /// </summary>
+    /// <returns>实际发布的通知条数（platform 侧 fanout 落库数）。</returns>
+    public async Task<int> PublishAsync(
+        string type,
+        string title,
+        string content,
+        Guid conversationId,
+        IEnumerable<Guid> recipientUserIds,
+        CancellationToken ct = default)
+    {
+        var recipients = recipientUserIds as IReadOnlyCollection<Guid> ?? recipientUserIds.ToList();
+        if (recipients.Count == 0) return 0;
+
+        try
+        {
+            return await mediator.Send(new PublishNotificationCommand(
+                Type: type,
+                Title: title,
+                Content: content,
+                Source: "im",
+                RelatedId: conversationId.ToString(),
+                RelatedType: "im-conversation",
+                RecipientUserIds: recipients,
+                RecipientRoles: null), ct);
+        }
+        catch
+        {
+            // 通知是旁路触达，失败不应影响 IM 发消息主链路，吞异常降级。
+            return 0;
+        }
+    }
+}
diff --git a/src/BuildFlow.Host/Services/Integration/InProcessAvatarUrlResolver.cs b/src/BuildFlow.Host/Services/Integration/InProcessAvatarUrlResolver.cs
index 0056cb8..01a6245 100644
--- a/src/BuildFlow.Host/Services/Integration/InProcessAvatarUrlResolver.cs
+++ b/src/BuildFlow.Host/Services/Integration/InProcessAvatarUrlResolver.cs
@@ -37,7 +37,7 @@ public class InProcessAvatarUrlResolver(IMediator mediator) : IAvatarUrlResolver
         // 其余视为 objectKey：通过 file 模块生成 24 小时有效的预签名 URL
         try
         {
-            var result = await mediator.Send(new GetFilePreviewQuery(AvatarBucket, avatarRef), ct);
+            var result = await mediator.Send(new GetFilePreviewQuery(avatarRef), ct);
             return result.PresignedUrl;
         }
         catch
diff --git a/src/BuildFlow.Host/Services/Integration/InProcessFileStorageClient.cs b/src/BuildFlow.Host/Services/Integration/InProcessFileStorageClient.cs
index d277cdc..74a9636 100644
--- a/src/BuildFlow.Host/Services/Integration/InProcessFileStorageClient.cs
+++ b/src/BuildFlow.Host/Services/Integration/InProcessFileStorageClient.cs
@@ -25,8 +25,9 @@ public class InProcessFileStorageClient(IMediator mediator) : IFileStorageClient
         string? authToken, // 进程内调用无需鉴权，token 忽略
         CancellationToken ct = default)
     {
-        // 通过 MediatR 命令调用 file 模块的 UploadFileCommandHandler（它内部走 IS3StorageService）
-        await mediator.Send(new UploadFileCommand(bucket, objectKey, content, contentType, content.Length), ct);
+        // 通过 MediatR 命令调用 file 模块的 UploadFileCommandHandler（它内部走 IS3StorageService）。
+        // bucket 由 handler 内的 IBucketResolver 统一解析，此处不再透传。
+        await mediator.Send(new UploadFileCommand(objectKey, content, contentType, content.Length), ct);
     }
 
     public async Task<Stream> DownloadAsync(
@@ -36,8 +37,9 @@ public class InProcessFileStorageClient(IMediator mediator) : IFileStorageClient
         CancellationToken ct = default)
     {
         // 通过 MediatR 查询调用 file 模块的 DownloadFileQueryHandler。
+        // bucket 由 handler 内的 IBucketResolver 统一解析，此处不再透传。
         // DownloadFileQuery 现在直接返回 S3 原始流（不再 buffer 成 byte[]），此处原样透传。
-        var result = await mediator.Send(new DownloadFileQuery(bucket, objectKey), ct);
+        var result = await mediator.Send(new DownloadFileQuery(objectKey), ct);
         return result.Stream;
     }
 }
diff --git a/src/modules/file/Application/Features/Files/Commands/DeleteFileCommand.cs b/src/modules/file/Application/Features/Files/Commands/DeleteFileCommand.cs
index c8c3716..e892789 100644
--- a/src/modules/file/Application/Features/Files/Commands/DeleteFileCommand.cs
+++ b/src/modules/file/Application/Features/Files/Commands/DeleteFileCommand.cs
@@ -4,4 +4,4 @@ namespace File.Application.Features.Files.Commands;
 
 
 /// <summary>删除文件命令。删 S3 对象并发布 FileDeletedEvent。</summary>
-public record DeleteFileCommand(string BucketName, string ObjectKey) : IRequest<Unit>;
+public record DeleteFileCommand(string ObjectKey) : IRequest<Unit>;
diff --git a/src/modules/file/Application/Features/Files/Commands/UploadFileCommand.cs b/src/modules/file/Application/Features/Files/Commands/UploadFileCommand.cs
index 1229bf5..b10ae31 100644
--- a/src/modules/file/Application/Features/Files/Commands/UploadFileCommand.cs
+++ b/src/modules/file/Application/Features/Files/Commands/UploadFileCommand.cs
@@ -5,5 +5,5 @@ namespace File.Application.Features.Files.Commands;
 
 
 /// <summary>上传文件命令。直传 S3 对象并发布 FileUploadedEvent。ContentHash 可选，由前端预检后附带，用于秒传查重。</summary>
-public record UploadFileCommand(string BucketName, string ObjectKey, Stream Data, string ContentType, long Size, string? ContentHash = null)
+public record UploadFileCommand(string ObjectKey, Stream Data, string ContentType, long Size, string? ContentHash = null)
     : IRequest<UploadFileResponse>;
diff --git a/src/modules/file/Application/Features/Files/Handlers/DeleteFileCommandHandler.cs b/src/modules/file/Application/Features/Files/Handlers/DeleteFileCommandHandler.cs
index b6001f1..277e119 100644
--- a/src/modules/file/Application/Features/Files/Handlers/DeleteFileCommandHandler.cs
+++ b/src/modules/file/Application/Features/Files/Handlers/DeleteFileCommandHandler.cs
@@ -1,3 +1,4 @@
+using File.Application.Common;
 using File.Application.Events;
 using File.Application.Features.Files.Commands;
 using File.Infrastructure.Persistence;
@@ -11,17 +12,19 @@ namespace File.Application.Features.Files.Handlers;
 /// 两者必须同步删除：若只删 S3 不删库，文件夹视图（读 DB）仍会显示已失效的文件；
 /// 若只删库不删 S3，对象存储会残留孤儿对象。S3 删除失败时阻断（避免库删了对象还在）。
 /// </summary>
-public class DeleteFileCommandHandler(IS3StorageService s3, FileDbContext db, IMediator mediator)
+public class DeleteFileCommandHandler(IS3StorageService s3, FileDbContext db, IBucketResolver bucketResolver, IMediator mediator)
     : IRequestHandler<DeleteFileCommand, Unit>
 {
     public async Task<Unit> Handle(DeleteFileCommand req, CancellationToken ct)
     {
+        var bucket = await bucketResolver.GetDefaultBucketAsync(ct);
+
         // 1. 删 S3 对象（先删存储，成功后再清库记录，保证不会出现"库没了但对象还在"的孤儿）
-        await s3.DeleteFileAsync(req.BucketName, req.ObjectKey, ct);
+        await s3.DeleteFileAsync(bucket, req.ObjectKey, ct);
 
         // 2. 删 FileMeta 记录（按 bucket + key 精确匹配，可能有 0~N 条）
         var metas = await db.Files
-            .Where(f => f.S3Bucket == req.BucketName && f.S3Key == req.ObjectKey)
+            .Where(f => f.S3Bucket == bucket && f.S3Key == req.ObjectKey)
             .ToListAsync(ct);
         if (metas.Count > 0)
         {
@@ -29,7 +32,7 @@ public class DeleteFileCommandHandler(IS3StorageService s3, FileDbContext db, IM
             await db.SaveChangesAsync(ct);
         }
 
-        await mediator.Publish(new FileDeletedEvent(req.BucketName, req.ObjectKey), ct);
+        await mediator.Publish(new FileDeletedEvent(bucket, req.ObjectKey), ct);
         return Unit.Value;
     }
 }
diff --git a/src/modules/file/Application/Features/Files/Handlers/DownloadFileQueryHandler.cs b/src/modules/file/Application/Features/Files/Handlers/DownloadFileQueryHandler.cs
index e6ab63b..dd8273d 100644
--- a/src/modules/file/Application/Features/Files/Handlers/DownloadFileQueryHandler.cs
+++ b/src/modules/file/Application/Features/Files/Handlers/DownloadFileQueryHandler.cs
@@ -1,3 +1,4 @@
+using File.Application.Common;
 using File.Application.Features.Files.DTOs;
 using File.Application.Features.Files.Queries;
 using File.Infrastructure.Storage;
@@ -9,11 +10,12 @@ namespace File.Application.Features.Files.Handlers;
 /// 下载文件查询处理器。从 S3 拉取响应流，原样透传给 Endpoint 写入 HTTP 响应体，
 /// 不再拷贝到内存，大文件零内存压力。真实 ContentType 由 S3 HeadObject/GetObject 返回。
 /// </summary>
-public class DownloadFileQueryHandler(IS3StorageService s3) : IRequestHandler<DownloadFileQuery, DownloadFileResult>
+public class DownloadFileQueryHandler(IS3StorageService s3, IBucketResolver bucketResolver) : IRequestHandler<DownloadFileQuery, DownloadFileResult>
 {
     public async Task<DownloadFileResult> Handle(DownloadFileQuery req, CancellationToken ct)
     {
-        var (stream, contentType) = await s3.DownloadFileAsync(req.BucketName, req.ObjectKey, ct);
+        var bucket = await bucketResolver.GetDefaultBucketAsync(ct);
+        var (stream, contentType) = await s3.DownloadFileAsync(bucket, req.ObjectKey, ct);
         // 文件名取 ObjectKey 最后一段（S3 key 可能含目录前缀）
         var fileName = req.ObjectKey.Contains('/')
             ? req.ObjectKey[(req.ObjectKey.LastIndexOf('/') + 1)..]
diff --git a/src/modules/file/Application/Features/Files/Handlers/GetFileContentQueryHandler.cs b/src/modules/file/Application/Features/Files/Handlers/GetFileContentQueryHandler.cs
index c4a1265..94fada4 100644
--- a/src/modules/file/Application/Features/Files/Handlers/GetFileContentQueryHandler.cs
+++ b/src/modules/file/Application/Features/Files/Handlers/GetFileContentQueryHandler.cs
@@ -1,3 +1,4 @@
+using File.Application.Common;
 using File.Application.Features.Files.DTOs;
 using File.Application.Features.Files.Queries;
 using File.Infrastructure.Storage;
@@ -5,14 +6,16 @@ using MediatR;
 
 namespace File.Application.Features.Files.Handlers;
 
-/// <summary>获取文件内容处理器。限定 10MB 上限，超限由 S3 侧截断。</summary>
-public class GetFileContentQueryHandler(IS3StorageService s3) : IRequestHandler<GetFileContentQuery, FileContentResult>
+/// <summary>获取文件内容处理器。限定 10MB 上限，超限由 S3 侧截断。bucket 从 IBucketResolver 统一获取。</summary>
+public class GetFileContentQueryHandler(IS3StorageService s3, IBucketResolver bucketResolver)
+    : IRequestHandler<GetFileContentQuery, FileContentResult>
 {
     private const long MaxContentBytes = 10 * 1024 * 1024; // 10 MB
 
     public async Task<FileContentResult> Handle(GetFileContentQuery req, CancellationToken ct)
     {
-        var content = await s3.GetFileContentAsync(req.BucketName, req.ObjectKey, MaxContentBytes, ct);
+        var bucket = await bucketResolver.GetDefaultBucketAsync(ct);
+        var content = await s3.GetFileContentAsync(bucket, req.ObjectKey, MaxContentBytes, ct);
         return new FileContentResult(content);
     }
 }
diff --git a/src/modules/file/Application/Features/Files/Handlers/GetFilePreviewQueryHandler.cs b/src/modules/file/Application/Features/Files/Handlers/GetFilePreviewQueryHandler.cs
index 5caaaf1..4488f08 100644
--- a/src/modules/file/Application/Features/Files/Handlers/GetFilePreviewQueryHandler.cs
+++ b/src/modules/file/Application/Features/Files/Handlers/GetFilePreviewQueryHandler.cs
@@ -1,3 +1,4 @@
+using File.Application.Common;
 using File.Application.Features.Files.DTOs;
 using File.Application.Features.Files.Queries;
 using File.Infrastructure.Storage;
@@ -6,13 +7,14 @@ using MediatR;
 namespace File.Application.Features.Files.Handlers;
 
 /// <summary>文件预览查询处理器。生成 24 小时有效的预签名 URL。</summary>
-public class GetFilePreviewQueryHandler(IS3StorageService s3) : IRequestHandler<GetFilePreviewQuery, FilePreviewResult>
+public class GetFilePreviewQueryHandler(IS3StorageService s3, IBucketResolver bucketResolver) : IRequestHandler<GetFilePreviewQuery, FilePreviewResult>
 {
     private static readonly TimeSpan PreviewExpiry = TimeSpan.FromHours(24);
 
     public async Task<FilePreviewResult> Handle(GetFilePreviewQuery req, CancellationToken ct)
     {
-        var url = await s3.GeneratePresignedUrlAsync(req.BucketName, req.ObjectKey, PreviewExpiry, ct);
+        var bucket = await bucketResolver.GetDefaultBucketAsync(ct);
+        var url = await s3.GeneratePresignedUrlAsync(bucket, req.ObjectKey, PreviewExpiry, ct);
         return new FilePreviewResult(url);
     }
 }
diff --git a/src/modules/file/Application/Features/Files/Handlers/GetOfficePreviewQueryHandler.cs b/src/modules/file/Application/Features/Files/Handlers/GetOfficePreviewQueryHandler.cs
index 353f804..c3f2c8b 100644
--- a/src/modules/file/Application/Features/Files/Handlers/GetOfficePreviewQueryHandler.cs
+++ b/src/modules/file/Application/Features/Files/Handlers/GetOfficePreviewQueryHandler.cs
@@ -1,3 +1,4 @@
+using File.Application.Common;
 using File.Application.Features.Files.DTOs;
 using File.Application.Features.Files.Queries;
 using File.Infrastructure.Storage;
@@ -10,7 +11,7 @@ namespace File.Application.Features.Files.Handlers;
 /// Office/PDF 文档预览查询处理器。生成 S3 预签名 URL（1 小时有效），
 /// 按 KKFileView 约定 Base64 编码后拼成 onlinePreview 地址返回。
 /// </summary>
-public class GetOfficePreviewQueryHandler(IS3StorageService s3, IOptions<KkFileViewOptions> kkOptions)
+public class GetOfficePreviewQueryHandler(IS3StorageService s3, IBucketResolver bucketResolver, IOptions<KkFileViewOptions> kkOptions)
     : IRequestHandler<GetOfficePreviewQuery, OfficePreviewResult>
 {
     /// <summary>Office 文档预签名有效期较短（1 小时），降低链接泄露风险。</summary>
@@ -18,7 +19,8 @@ public class GetOfficePreviewQueryHandler(IS3StorageService s3, IOptions<KkFileV
 
     public async Task<OfficePreviewResult> Handle(GetOfficePreviewQuery req, CancellationToken ct)
     {
-        var presignedUrl = await s3.GeneratePresignedUrlAsync(req.BucketName, req.ObjectKey, PreviewExpiry, ct);
+        var bucket = await bucketResolver.GetDefaultBucketAsync(ct);
+        var presignedUrl = await s3.GeneratePresignedUrlAsync(bucket, req.ObjectKey, PreviewExpiry, ct);
 
         // KKFileView onlinePreview 约定：url 参数为 Base64 编码的文件直链
         var encoded = Convert.ToBase64String(System.Text.Encoding.UTF8.GetBytes(presignedUrl));
diff --git a/src/modules/file/Application/Features/Files/Handlers/ListFilesQueryHandler.cs b/src/modules/file/Application/Features/Files/Handlers/ListFilesQueryHandler.cs
index b8ff3df..02e3721 100644
--- a/src/modules/file/Application/Features/Files/Handlers/ListFilesQueryHandler.cs
+++ b/src/modules/file/Application/Features/Files/Handlers/ListFilesQueryHandler.cs
@@ -1,3 +1,4 @@
+using File.Application.Common;
 using File.Application.Features.Files.DTOs;
 using File.Application.Features.Files.Queries;
 using File.Infrastructure.Storage;
@@ -6,7 +7,7 @@ using MediatR;
 namespace File.Application.Features.Files.Handlers;
 
 /// <summary>列文件查询处理器。默认 100 条，上限 1000 条分页代理 S3。</summary>
-public class ListFilesQueryHandler(IS3StorageService s3) : IRequestHandler<ListFilesQuery, ListFilesResponse>
+public class ListFilesQueryHandler(IS3StorageService s3, IBucketResolver bucketResolver) : IRequestHandler<ListFilesQuery, ListFilesResponse>
 {
     private const int DefaultMaxKeys = 100;
     private const int MaxListKeys = 1000;
@@ -14,7 +15,8 @@ public class ListFilesQueryHandler(IS3StorageService s3) : IRequestHandler<ListF
     public async Task<ListFilesResponse> Handle(ListFilesQuery req, CancellationToken ct)
     {
         var maxKeys = (req.MaxKeys is null or <= 0) ? DefaultMaxKeys : Math.Min(req.MaxKeys.Value, MaxListKeys);
-        var s3Result = await s3.ListObjectsAsync(req.BucketName, req.Prefix, maxKeys, req.ContinuationToken, ct);
+        var bucket = await bucketResolver.GetDefaultBucketAsync(ct);
+        var s3Result = await s3.ListObjectsAsync(bucket, req.Prefix, maxKeys, req.ContinuationToken, ct);
         var files = s3Result.Files
             .Select(f => new FileListItemDto(f.Key, f.Size, f.LastModified.ToString("O"), f.ETag))
             .ToList();
diff --git a/src/modules/file/Application/Features/Files/Handlers/UploadFileCommandHandler.cs b/src/modules/file/Application/Features/Files/Handlers/UploadFileCommandHandler.cs
index 37e16d5..2ba86a8 100644
--- a/src/modules/file/Application/Features/Files/Handlers/UploadFileCommandHandler.cs
+++ b/src/modules/file/Application/Features/Files/Handlers/UploadFileCommandHandler.cs
@@ -1,4 +1,5 @@
 using BuildFlow.Shared.Domain.Common;
+using File.Application.Common;
 using File.Application.Events;
 using File.Application.Features.Files.Commands;
 using File.Application.Features.Files.DTOs;
@@ -19,6 +20,7 @@ public class UploadFileCommandHandler(
     IS3StorageService s3,
     FileDbContext db,
     ICurrentUserContext currentUser,
+    IBucketResolver bucketResolver,
     IMediator mediator) : IRequestHandler<UploadFileCommand, UploadFileResponse>
 {
     private const long MaxFileSize = 500 * 1024 * 1024; // 500 MiB
@@ -32,10 +34,12 @@ public class UploadFileCommandHandler(
             throw new TooLargeException("文件大小不能超过 500MB");
         }
 
-        await s3.UploadFileAsync(req.BucketName, req.ObjectKey, req.Data, req.ContentType, ct);
+        var bucket = await bucketResolver.GetDefaultBucketAsync(ct);
+
+        await s3.UploadFileAsync(bucket, req.ObjectKey, req.Data, req.ContentType, ct);
 
         // 落 FileMeta：直传为根目录散落文件（FolderId=null）。唯一约束 (OwnerId,ContentHash) 冲突时复用。
-        if (!await db.Files.AnyAsync(f => f.S3Bucket == req.BucketName && f.S3Key == req.ObjectKey, ct))
+        if (!await db.Files.AnyAsync(f => f.S3Bucket == bucket && f.S3Key == req.ObjectKey, ct))
         {
             db.Files.Add(new FileMeta
             {
@@ -43,7 +47,7 @@ public class UploadFileCommandHandler(
                 FolderId = null,
                 Name = req.ObjectKey,
                 S3Key = req.ObjectKey,
-                S3Bucket = req.BucketName,
+                S3Bucket = bucket,
                 Size = req.Size,
                 ContentType = string.IsNullOrEmpty(req.ContentType) ? "application/octet-stream" : req.ContentType,
                 ContentHash = req.ContentHash,
@@ -62,7 +66,7 @@ public class UploadFileCommandHandler(
             }
         }
 
-        await mediator.Publish(new FileUploadedEvent(req.BucketName, req.ObjectKey), ct);
+        await mediator.Publish(new FileUploadedEvent(bucket, req.ObjectKey), ct);
 
         return new UploadFileResponse("uploaded", req.ObjectKey);
     }
diff --git a/src/modules/file/Application/Features/Files/Queries/DownloadFileQuery.cs b/src/modules/file/Application/Features/Files/Queries/DownloadFileQuery.cs
index 4a75a00..d96cd03 100644
--- a/src/modules/file/Application/Features/Files/Queries/DownloadFileQuery.cs
+++ b/src/modules/file/Application/Features/Files/Queries/DownloadFileQuery.cs
@@ -5,4 +5,4 @@ namespace File.Application.Features.Files.Queries;
 
 
 /// <summary>下载文件查询。返回字节流。</summary>
-public record DownloadFileQuery(string BucketName, string ObjectKey) : IRequest<DownloadFileResult>;
+public record DownloadFileQuery(string ObjectKey) : IRequest<DownloadFileResult>;
diff --git a/src/modules/file/Application/Features/Files/Queries/GetFileContentQuery.cs b/src/modules/file/Application/Features/Files/Queries/GetFileContentQuery.cs
index c249a82..1d1ae8b 100644
--- a/src/modules/file/Application/Features/Files/Queries/GetFileContentQuery.cs
+++ b/src/modules/file/Application/Features/Files/Queries/GetFileContentQuery.cs
@@ -4,5 +4,5 @@ using MediatR;
 namespace File.Application.Features.Files.Queries;
 
 
-/// <summary>获取文件文本内容查询。</summary>
-public record GetFileContentQuery(string BucketName, string ObjectKey) : IRequest<FileContentResult>;
+/// <summary>获取文件文本内容查询。bucket 由 IBucketResolver 统一解析。</summary>
+public record GetFileContentQuery(string ObjectKey) : IRequest<FileContentResult>;
diff --git a/src/modules/file/Application/Features/Files/Queries/GetFilePreviewQuery.cs b/src/modules/file/Application/Features/Files/Queries/GetFilePreviewQuery.cs
index 60fee59..fd819de 100644
--- a/src/modules/file/Application/Features/Files/Queries/GetFilePreviewQuery.cs
+++ b/src/modules/file/Application/Features/Files/Queries/GetFilePreviewQuery.cs
@@ -5,4 +5,4 @@ namespace File.Application.Features.Files.Queries;
 
 
 /// <summary>获取文件预签名预览 URL 查询。</summary>
-public record GetFilePreviewQuery(string BucketName, string ObjectKey) : IRequest<FilePreviewResult>;
+public record GetFilePreviewQuery(string ObjectKey) : IRequest<FilePreviewResult>;
diff --git a/src/modules/file/Application/Features/Files/Queries/GetOfficePreviewQuery.cs b/src/modules/file/Application/Features/Files/Queries/GetOfficePreviewQuery.cs
index 3bfb325..5bfe0a7 100644
--- a/src/modules/file/Application/Features/Files/Queries/GetOfficePreviewQuery.cs
+++ b/src/modules/file/Application/Features/Files/Queries/GetOfficePreviewQuery.cs
@@ -7,4 +7,4 @@ namespace File.Application.Features.Files.Queries;
 /// 获取 Office/PDF 文档在线预览地址查询。
 /// 生成 S3 预签名 URL 后拼装为 KKFileView 预览链接，供前端 window.open 打开。
 /// </summary>
-public record GetOfficePreviewQuery(string BucketName, string ObjectKey) : IRequest<OfficePreviewResult>;
+public record GetOfficePreviewQuery(string ObjectKey) : IRequest<OfficePreviewResult>;
diff --git a/src/modules/file/Application/Features/Files/Queries/ListFilesQuery.cs b/src/modules/file/Application/Features/Files/Queries/ListFilesQuery.cs
index 9009078..1dfc6c4 100644
--- a/src/modules/file/Application/Features/Files/Queries/ListFilesQuery.cs
+++ b/src/modules/file/Application/Features/Files/Queries/ListFilesQuery.cs
@@ -5,5 +5,5 @@ namespace File.Application.Features.Files.Queries;
 
 
 /// <summary>列文件查询。支持前缀、分页大小、续传 token。</summary>
-public record ListFilesQuery(string BucketName, string? Prefix, int? MaxKeys, string? ContinuationToken)
+public record ListFilesQuery(string? Prefix, int? MaxKeys, string? ContinuationToken)
     : IRequest<ListFilesResponse>;
diff --git a/src/modules/file/Application/Features/Files/Validators/DeleteFileCommandValidator.cs b/src/modules/file/Application/Features/Files/Validators/DeleteFileCommandValidator.cs
index ac54489..58253be 100644
--- a/src/modules/file/Application/Features/Files/Validators/DeleteFileCommandValidator.cs
+++ b/src/modules/file/Application/Features/Files/Validators/DeleteFileCommandValidator.cs
@@ -9,7 +9,6 @@ public class DeleteFileCommandValidator : AbstractValidator<DeleteFileCommand>
 {
     public DeleteFileCommandValidator()
     {
-        RuleFor(x => x.BucketName).Must(SanitizeRules.IsValidBucketName).WithMessage("无效的存储桶名称");
         RuleFor(x => x.ObjectKey).Must(SanitizeRules.IsValidObjectKey).WithMessage("无效的对象 key");
     }
 }
diff --git a/src/modules/file/Application/Features/Files/Validators/DownloadFileQueryValidator.cs b/src/modules/file/Application/Features/Files/Validators/DownloadFileQueryValidator.cs
index 7ad8be2..5cd699d 100644
--- a/src/modules/file/Application/Features/Files/Validators/DownloadFileQueryValidator.cs
+++ b/src/modules/file/Application/Features/Files/Validators/DownloadFileQueryValidator.cs
@@ -9,7 +9,6 @@ public class DownloadFileQueryValidator : AbstractValidator<DownloadFileQuery>
 {
     public DownloadFileQueryValidator()
     {
-        RuleFor(x => x.BucketName).Must(SanitizeRules.IsValidBucketName).WithMessage("无效的存储桶名称");
         RuleFor(x => x.ObjectKey).Must(SanitizeRules.IsValidObjectKey).WithMessage("无效的对象 key");
     }
 }
diff --git a/src/modules/file/Application/Features/Files/Validators/GetFileContentQueryValidator.cs b/src/modules/file/Application/Features/Files/Validators/GetFileContentQueryValidator.cs
index a52fa12..adc930e 100644
--- a/src/modules/file/Application/Features/Files/Validators/GetFileContentQueryValidator.cs
+++ b/src/modules/file/Application/Features/Files/Validators/GetFileContentQueryValidator.cs
@@ -9,7 +9,6 @@ public class GetFileContentQueryValidator : AbstractValidator<GetFileContentQuer
 {
     public GetFileContentQueryValidator()
     {
-        RuleFor(x => x.BucketName).Must(SanitizeRules.IsValidBucketName).WithMessage("无效的存储桶名称");
         RuleFor(x => x.ObjectKey).Must(SanitizeRules.IsValidObjectKey).WithMessage("无效的对象 key");
     }
 }
diff --git a/src/modules/file/Application/Features/Files/Validators/GetFilePreviewQueryValidator.cs b/src/modules/file/Application/Features/Files/Validators/GetFilePreviewQueryValidator.cs
index 90969ef..f7e9854 100644
--- a/src/modules/file/Application/Features/Files/Validators/GetFilePreviewQueryValidator.cs
+++ b/src/modules/file/Application/Features/Files/Validators/GetFilePreviewQueryValidator.cs
@@ -9,7 +9,6 @@ public class GetFilePreviewQueryValidator : AbstractValidator<GetFilePreviewQuer
 {
     public GetFilePreviewQueryValidator()
     {
-        RuleFor(x => x.BucketName).Must(SanitizeRules.IsValidBucketName).WithMessage("无效的存储桶名称");
         RuleFor(x => x.ObjectKey).Must(SanitizeRules.IsValidObjectKey).WithMessage("无效的对象 key");
     }
 }
diff --git a/src/modules/file/Application/Features/Files/Validators/ListFilesQueryValidator.cs b/src/modules/file/Application/Features/Files/Validators/ListFilesQueryValidator.cs
index 16c9b28..a477c4d 100644
--- a/src/modules/file/Application/Features/Files/Validators/ListFilesQueryValidator.cs
+++ b/src/modules/file/Application/Features/Files/Validators/ListFilesQueryValidator.cs
@@ -9,6 +9,5 @@ public class ListFilesQueryValidator : AbstractValidator<ListFilesQuery>
 {
     public ListFilesQueryValidator()
     {
-        RuleFor(x => x.BucketName).Must(SanitizeRules.IsValidBucketName).WithMessage("无效的存储桶名称");
     }
 }
diff --git a/src/modules/file/Application/Features/Files/Validators/UploadFileCommandValidator.cs b/src/modules/file/Application/Features/Files/Validators/UploadFileCommandValidator.cs
index 7d962e9..229c4e5 100644
--- a/src/modules/file/Application/Features/Files/Validators/UploadFileCommandValidator.cs
+++ b/src/modules/file/Application/Features/Files/Validators/UploadFileCommandValidator.cs
@@ -9,7 +9,6 @@ public class UploadFileCommandValidator : AbstractValidator<UploadFileCommand>
 {
     public UploadFileCommandValidator()
     {
-        RuleFor(x => x.BucketName).Must(SanitizeRules.IsValidBucketName).WithMessage("无效的存储桶名称");
         RuleFor(x => x.ObjectKey).Must(SanitizeRules.IsValidObjectKey).WithMessage("无效的对象 key");
     }
 }
diff --git a/src/modules/file/Application/Features/Folders/Handlers/UploadToFolderCommandHandler.cs b/src/modules/file/Application/Features/Folders/Handlers/UploadToFolderCommandHandler.cs
index b2d4dff..bda3d3b 100644
--- a/src/modules/file/Application/Features/Folders/Handlers/UploadToFolderCommandHandler.cs
+++ b/src/modules/file/Application/Features/Folders/Handlers/UploadToFolderCommandHandler.cs
@@ -7,19 +7,18 @@ using File.Domain.Exceptions;
 using File.Infrastructure.Persistence;
 using File.Infrastructure.Storage;
 using MediatR;
-using Microsoft.Extensions.Configuration;
 
 namespace File.Application.Features.Folders.Handlers;
 
 /// <summary>
 /// 上传文件到文件夹处理器。校验 500MiB 上限，UUID 作 S3 key，落库失败补偿删 S3。
-/// bucket 从配置 FileService:Bucket 读取（与直传/预览/下载/删除统一，不再硬编码 "files"）。
+/// bucket 统一从 IBucketResolver 获取（与直传/预览/下载/删除一致，不再从配置或前端参数读取）。
 /// </summary>
 public class UploadToFolderCommandHandler(
     FileDbContext db,
     IS3StorageService s3,
     ICurrentUserContext currentUser,
-    IConfiguration config) : IRequestHandler<UploadToFolderCommand, FileMetaDto>
+    IBucketResolver bucketResolver) : IRequestHandler<UploadToFolderCommand, FileMetaDto>
 {
     private const long MaxUploadBytes = 500 * 1024 * 1024; // 500 MiB
 
@@ -29,8 +28,8 @@ public class UploadToFolderCommandHandler(
         if (req.Size > MaxUploadBytes)
             throw new TooLargeException("文件大小超过上限 500MB");
 
-        // bucket 与直传/预览/下载统一（前端默认 build-flow），不再硬编码 "files"
-        var bucket = config["FileService:Bucket"] ?? "build-flow";
+        // bucket 统一从 IBucketResolver 获取（默认 build-flow），与直传/预览/下载/删除一致
+        var bucket = await bucketResolver.GetDefaultBucketAsync(ct);
 
         var safeName = SanitizeRules.SanitizeFilename(req.FileName.Trim());
         var s3Key = Guid.NewGuid().ToString(); // 永远用 UUID，不用原文件名
diff --git a/src/modules/file/Application/Features/Multipart/Commands/AbortMultipartCommand.cs b/src/modules/file/Application/Features/Multipart/Commands/AbortMultipartCommand.cs
index f326ece..a1e2ce4 100644
--- a/src/modules/file/Application/Features/Multipart/Commands/AbortMultipartCommand.cs
+++ b/src/modules/file/Application/Features/Multipart/Commands/AbortMultipartCommand.cs
@@ -4,4 +4,4 @@ namespace File.Application.Features.Multipart.Commands;
 
 
 /// <summary>中止分片上传命令。清理已传分片。</summary>
-public record AbortMultipartCommand(string BucketName, string ObjectKey, string UploadId) : IRequest<Unit>;
+public record AbortMultipartCommand(string ObjectKey, string UploadId) : IRequest<Unit>;
diff --git a/src/modules/file/Application/Features/Multipart/Commands/CompleteMultipartCommand.cs b/src/modules/file/Application/Features/Multipart/Commands/CompleteMultipartCommand.cs
index bfa4d80..e193c9a 100644
--- a/src/modules/file/Application/Features/Multipart/Commands/CompleteMultipartCommand.cs
+++ b/src/modules/file/Application/Features/Multipart/Commands/CompleteMultipartCommand.cs
@@ -8,7 +8,6 @@ namespace File.Application.Features.Multipart.Commands;
 /// FileName/Size 可选：完成后用于创建 FileMeta（分片秒传查重记录），不带则不落 FileMeta（老客户端兼容）。
 /// </summary>
 public record CompleteMultipartCommand(
-    string BucketName,
     string ObjectKey,
     string UploadId,
     List<CompletedPartDto> Parts,
diff --git a/src/modules/file/Application/Features/Multipart/Commands/InitMultipartCommand.cs b/src/modules/file/Application/Features/Multipart/Commands/InitMultipartCommand.cs
index d458c24..b3c17d8 100644
--- a/src/modules/file/Application/Features/Multipart/Commands/InitMultipartCommand.cs
+++ b/src/modules/file/Application/Features/Multipart/Commands/InitMultipartCommand.cs
@@ -9,7 +9,6 @@ namespace File.Application.Features.Multipart.Commands;
 /// 秒传判定用 (OwnerId, ContentHash, Size) 三元组（与 CheckFileQuery 对齐）。
 /// </summary>
 public record InitMultipartCommand(
-    string BucketName,
     string ObjectKey,
     string? ContentHash = null,
     int? TotalParts = null,
diff --git a/src/modules/file/Application/Features/Multipart/Commands/UploadPartCommand.cs b/src/modules/file/Application/Features/Multipart/Commands/UploadPartCommand.cs
index 6f9d045..2c9bea3 100644
--- a/src/modules/file/Application/Features/Multipart/Commands/UploadPartCommand.cs
+++ b/src/modules/file/Application/Features/Multipart/Commands/UploadPartCommand.cs
@@ -5,5 +5,5 @@ namespace File.Application.Features.Multipart.Commands;
 
 
 /// <summary>上传单分片命令。携带 uploadId 与 partNumber 续传。</summary>
-public record UploadPartCommand(string BucketName, string ObjectKey, string UploadId, int PartNumber, Stream Data)
+public record UploadPartCommand(string ObjectKey, string UploadId, int PartNumber, Stream Data)
     : IRequest<UploadPartResult>;
diff --git a/src/modules/file/Application/Features/Multipart/Handlers/AbortMultipartCommandHandler.cs b/src/modules/file/Application/Features/Multipart/Handlers/AbortMultipartCommandHandler.cs
index 422d61a..be6b8bc 100644
--- a/src/modules/file/Application/Features/Multipart/Handlers/AbortMultipartCommandHandler.cs
+++ b/src/modules/file/Application/Features/Multipart/Handlers/AbortMultipartCommandHandler.cs
@@ -31,7 +31,7 @@ public class AbortMultipartCommandHandler(
             throw new ConflictException("上传会话已结束，不可重复中止");
         }
 
-        await s3.AbortMultipartUploadAsync(req.BucketName, req.ObjectKey, req.UploadId, ct);
+        await s3.AbortMultipartUploadAsync(session.BucketName, req.ObjectKey, req.UploadId, ct);
 
         session.Status = UploadSessionStatus.Aborted;
         await db.SaveChangesAsync(ct);
diff --git a/src/modules/file/Application/Features/Multipart/Handlers/CompleteMultipartCommandHandler.cs b/src/modules/file/Application/Features/Multipart/Handlers/CompleteMultipartCommandHandler.cs
index 20069b3..304bf8a 100644
--- a/src/modules/file/Application/Features/Multipart/Handlers/CompleteMultipartCommandHandler.cs
+++ b/src/modules/file/Application/Features/Multipart/Handlers/CompleteMultipartCommandHandler.cs
@@ -1,4 +1,5 @@
 using BuildFlow.Shared.Domain.Common;
+using File.Application.Common;
 using File.Application.Features.Multipart.Commands;
 using File.Application.Features.Multipart.DTOs;
 using File.Domain.Entities;
@@ -19,11 +20,13 @@ namespace File.Application.Features.Multipart.Handlers;
 public class CompleteMultipartCommandHandler(
     IS3StorageService s3,
     FileDbContext db,
-    ICurrentUserContext currentUser) : IRequestHandler<CompleteMultipartCommand, CompleteMultipartResult>
+    ICurrentUserContext currentUser,
+    IBucketResolver bucketResolver) : IRequestHandler<CompleteMultipartCommand, CompleteMultipartResult>
 {
     public async Task<CompleteMultipartResult> Handle(CompleteMultipartCommand req, CancellationToken ct)
     {
         var owner = currentUser.GetRequiredUserId();
+        var bucket = await bucketResolver.GetDefaultBucketAsync(ct);
 
         var session = await db.UploadSessions.FirstOrDefaultAsync(s => s.UploadId == req.UploadId, ct);
         if (session is null || session.OwnerId != owner)
@@ -36,7 +39,7 @@ public class CompleteMultipartCommandHandler(
         }
 
         var parts = req.Parts.Select(p => new CompletedPart(p.PartNumber, p.ETag)).ToList();
-        await s3.CompleteMultipartUploadAsync(req.BucketName, req.ObjectKey, req.UploadId, parts, ct);
+        await s3.CompleteMultipartUploadAsync(bucket, req.ObjectKey, req.UploadId, parts, ct);
 
         // S3 成功后落库：session 终态 + FileMeta（供秒传查重），单次 SaveChanges 保证原子
         session.Status = UploadSessionStatus.Completed;
@@ -71,6 +74,6 @@ public class CompleteMultipartCommandHandler(
             await db.SaveChangesAsync(ct);
         }
 
-        return new CompleteMultipartResult($"{req.BucketName}/{req.ObjectKey}");
+        return new CompleteMultipartResult($"{bucket}/{req.ObjectKey}");
     }
 }
diff --git a/src/modules/file/Application/Features/Multipart/Handlers/InitMultipartCommandHandler.cs b/src/modules/file/Application/Features/Multipart/Handlers/InitMultipartCommandHandler.cs
index 1410fb2..05b950f 100644
--- a/src/modules/file/Application/Features/Multipart/Handlers/InitMultipartCommandHandler.cs
+++ b/src/modules/file/Application/Features/Multipart/Handlers/InitMultipartCommandHandler.cs
@@ -1,4 +1,5 @@
 using BuildFlow.Shared.Domain.Common;
+using File.Application.Common;
 using File.Application.Features.Multipart.Commands;
 using File.Application.Features.Multipart.DTOs;
 using File.Domain.Entities;
@@ -18,11 +19,13 @@ namespace File.Application.Features.Multipart.Handlers;
 public class InitMultipartCommandHandler(
     IS3StorageService s3,
     FileDbContext db,
-    ICurrentUserContext currentUser) : IRequestHandler<InitMultipartCommand, InitMultipartResult>
+    ICurrentUserContext currentUser,
+    IBucketResolver bucketResolver) : IRequestHandler<InitMultipartCommand, InitMultipartResult>
 {
     public async Task<InitMultipartResult> Handle(InitMultipartCommand req, CancellationToken ct)
     {
         var owner = currentUser.GetRequiredUserId();
+        var bucket = await bucketResolver.GetDefaultBucketAsync(ct);
 
         // 1. 秒传命中：同用户已有相同内容哈希文件，零字节复用。
         //    判定三元组 (OwnerId, ContentHash, Size) 与 CheckFileQuery 对齐——Size 防哈希碰撞误判。
@@ -40,7 +43,7 @@ public class InitMultipartCommandHandler(
         // 2. 幂等复用：同一用户同一对象若已有 Active 会话，直接返回其 uploadId
         var existing = await db.UploadSessions
             .FirstOrDefaultAsync(s => s.OwnerId == owner
-                && s.BucketName == req.BucketName
+                && s.BucketName == bucket
                 && s.ObjectKey == req.ObjectKey
                 && s.Status == UploadSessionStatus.Active, ct);
         if (existing is not null)
@@ -49,11 +52,11 @@ public class InitMultipartCommandHandler(
         }
 
         // 3. 真正发起 S3 multipart upload
-        var uploadId = await s3.CreateMultipartUploadAsync(req.BucketName, req.ObjectKey, ct);
+        var uploadId = await s3.CreateMultipartUploadAsync(bucket, req.ObjectKey, ct);
 
         var session = new MultipartUploadSession
         {
-            BucketName = req.BucketName,
+            BucketName = bucket,
             ObjectKey = req.ObjectKey,
             UploadId = uploadId,
             ContentHash = req.ContentHash,
diff --git a/src/modules/file/Application/Features/Multipart/Handlers/UploadPartCommandHandler.cs b/src/modules/file/Application/Features/Multipart/Handlers/UploadPartCommandHandler.cs
index bce29e7..940c445 100644
--- a/src/modules/file/Application/Features/Multipart/Handlers/UploadPartCommandHandler.cs
+++ b/src/modules/file/Application/Features/Multipart/Handlers/UploadPartCommandHandler.cs
@@ -38,7 +38,7 @@ public class UploadPartCommandHandler(
             throw new ConflictException("上传会话已结束，不可继续上传");
         }
 
-        var etag = await s3.UploadPartAsync(req.BucketName, req.ObjectKey, req.UploadId, req.PartNumber, req.Data, ct);
+        var etag = await s3.UploadPartAsync(session.BucketName, req.ObjectKey, req.UploadId, req.PartNumber, req.Data, ct);
         return new UploadPartResult(etag);
     }
 }
diff --git a/src/modules/file/Application/Features/Multipart/Validators/AbortMultipartCommandValidator.cs b/src/modules/file/Application/Features/Multipart/Validators/AbortMultipartCommandValidator.cs
index 22f5c89..c827056 100644
--- a/src/modules/file/Application/Features/Multipart/Validators/AbortMultipartCommandValidator.cs
+++ b/src/modules/file/Application/Features/Multipart/Validators/AbortMultipartCommandValidator.cs
@@ -9,7 +9,6 @@ public class AbortMultipartCommandValidator : AbstractValidator<AbortMultipartCo
 {
     public AbortMultipartCommandValidator()
     {
-        RuleFor(x => x.BucketName).Must(SanitizeRules.IsValidBucketName).WithMessage("无效的存储桶名称");
         RuleFor(x => x.ObjectKey).Must(SanitizeRules.IsValidObjectKey).WithMessage("无效的对象 key");
         RuleFor(x => x.UploadId).NotEmpty().WithMessage("upload_id 不能为空");
     }
diff --git a/src/modules/file/Application/Features/Multipart/Validators/CompleteMultipartCommandValidator.cs b/src/modules/file/Application/Features/Multipart/Validators/CompleteMultipartCommandValidator.cs
index 6ec06f4..c187b41 100644
--- a/src/modules/file/Application/Features/Multipart/Validators/CompleteMultipartCommandValidator.cs
+++ b/src/modules/file/Application/Features/Multipart/Validators/CompleteMultipartCommandValidator.cs
@@ -9,7 +9,6 @@ public class CompleteMultipartCommandValidator : AbstractValidator<CompleteMulti
 {
     public CompleteMultipartCommandValidator()
     {
-        RuleFor(x => x.BucketName).Must(SanitizeRules.IsValidBucketName).WithMessage("无效的存储桶名称");
         RuleFor(x => x.ObjectKey).Must(SanitizeRules.IsValidObjectKey).WithMessage("无效的对象 key");
         RuleFor(x => x.UploadId).NotEmpty().WithMessage("upload_id 不能为空");
         RuleFor(x => x.Parts).NotEmpty().WithMessage("parts 不能为空");
diff --git a/src/modules/file/Application/Features/Multipart/Validators/InitMultipartCommandValidator.cs b/src/modules/file/Application/Features/Multipart/Validators/InitMultipartCommandValidator.cs
index 09f1034..ca2c20b 100644
--- a/src/modules/file/Application/Features/Multipart/Validators/InitMultipartCommandValidator.cs
+++ b/src/modules/file/Application/Features/Multipart/Validators/InitMultipartCommandValidator.cs
@@ -9,7 +9,6 @@ public class InitMultipartCommandValidator : AbstractValidator<InitMultipartComm
 {
     public InitMultipartCommandValidator()
     {
-        RuleFor(x => x.BucketName).Must(SanitizeRules.IsValidBucketName).WithMessage("无效的存储桶名称");
         RuleFor(x => x.ObjectKey).Must(SanitizeRules.IsValidObjectKey).WithMessage("无效的对象 key");
     }
 }
diff --git a/src/modules/file/Application/Features/Multipart/Validators/UploadPartCommandValidator.cs b/src/modules/file/Application/Features/Multipart/Validators/UploadPartCommandValidator.cs
index 338c007..997fa06 100644
--- a/src/modules/file/Application/Features/Multipart/Validators/UploadPartCommandValidator.cs
+++ b/src/modules/file/Application/Features/Multipart/Validators/UploadPartCommandValidator.cs
@@ -9,7 +9,6 @@ public class UploadPartCommandValidator : AbstractValidator<UploadPartCommand>
 {
     public UploadPartCommandValidator()
     {
-        RuleFor(x => x.BucketName).Must(SanitizeRules.IsValidBucketName).WithMessage("无效的存储桶名称");
         RuleFor(x => x.ObjectKey).Must(SanitizeRules.IsValidObjectKey).WithMessage("无效的对象 key");
         RuleFor(x => x.UploadId).NotEmpty().WithMessage("upload_id 不能为空");
         RuleFor(x => x.PartNumber).GreaterThan(0).WithMessage("part_number 必须大于 0");
diff --git a/src/modules/platform/Infrastructure/Persistence/SeedData.cs b/src/modules/platform/Infrastructure/Persistence/SeedData.cs
index de9e256..5b49917 100644
--- a/src/modules/platform/Infrastructure/Persistence/SeedData.cs
+++ b/src/modules/platform/Infrastructure/Persistence/SeedData.cs
@@ -142,6 +142,29 @@ public static class SeedData
 
         if (permissions.Count == 0) return;
 
+        // 释放主键冲突：历史库可能存在与新种子同 Id 但不同 Code 的（已软删）残留记录，
+        // 导致 AddRangeAsync 主键冲突（23505）。这里物理删除这些占位记录，释放 Guid。
+        var seedIds = permissions.Select(p => p.Id).ToList();
+        var conflicting = await db.Permissions
+            .IgnoreQueryFilters()
+            .Where(p => seedIds.Contains(p.Id))
+            .Select(p => new { p.Id, p.Code })
+            .ToListAsync();
+        if (conflicting.Count > 0)
+        {
+            // 全程用原生 SQL 物理清理，避免 ChangeTracker 与外键级联互相冲突导致并发异常。
+            // conflictIds 来自上面数据库查询的 Guid 主键，非用户输入，无注入风险；EF1003 在此为误报。
+            var conflictIds = conflicting.Select(c => c.Id).ToList();
+#pragma warning disable EF1003
+            var idList = string.Join(", ", conflictIds.Select(id => "'" + id.ToString() + "'"));
+            // 先删角色-权限关联（该表无软删除），再物理删残留权限本身释放主键。
+            await db.Database.ExecuteSqlRawAsync(
+                "DELETE FROM role_permissions WHERE permission_id IN (" + idList + ");");
+            await db.Database.ExecuteSqlRawAsync(
+                "DELETE FROM permissions WHERE id IN (" + idList + ");");
+#pragma warning restore EF1003
+        }
+
         await db.Permissions.AddRangeAsync(permissions);
         await db.SaveChangesAsync();
     }
@@ -182,7 +205,7 @@ public static class SeedData
         // id 列表来自上面的数据库查询（Guid 主键），非用户输入，用 string.Concat / string.Join 拼成 SQL 字面量无注入风险；
         // permissions 表主键列名为带引号的 "Id"（EF 配置的 PascalCase 列名）。
         var idList = string.Join(", ", deprecatedPermissionIds.Select(id => "'" + id.ToString() + "'"));
-        var sql = "DELETE FROM permissions WHERE \"Id\" IN (" + idList + ");";
+        var sql = "DELETE FROM permissions WHERE id IN (" + idList + ");";
         await db.Database.ExecuteSqlRawAsync(sql);
     }
 
diff --git a/src/modules/workflow/Domain/Engine/WorkflowGraph.cs b/src/modules/workflow/Domain/Engine/WorkflowGraph.cs
new file mode 100644
index 0000000..2993c65
--- /dev/null
+++ b/src/modules/workflow/Domain/Engine/WorkflowGraph.cs
@@ -0,0 +1,149 @@
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using Workflow.Domain.Enums;
+
+namespace Workflow.Domain.Engine;
+
+/// <summary>
+/// X6 graph 的强类型模型，与 X6 toJSON/fromJSON 原生格式兼容。
+/// 替代裸 JsonDocument，供 ProcessEngine / 校验器 / 迁移脚本统一读写。
+/// 顶层结构为 { nodes: [], edges: [] }（X6 fromJSON 支持的两种等价格式之一）。
+/// </summary>
+public sealed class WorkflowGraph
+{
+    [JsonPropertyName("nodes")]
+    public List<GraphNode> Nodes { get; set; } = new();
+
+    [JsonPropertyName("edges")]
+    public List<GraphEdge> Edges { get; set; } = new();
+
+    /// <summary>空图工厂（容错用）。</summary>
+    public static WorkflowGraph Empty() => new();
+}
+
+/// <summary>
+/// X6 节点。shape 决定渲染器并反推 NodeType（见 <see cref="WorkflowShapeMap"/>）；
+/// 业务配置统一进 data；x/y/width/height/ports 为几何与渲染信息。
+/// </summary>
+public sealed class GraphNode
+{
+    [JsonPropertyName("id")]
+    public string Id { get; set; } = string.Empty;
+
+    [JsonPropertyName("shape")]
+    public string Shape { get; set; } = string.Empty;
+
+    [JsonPropertyName("x")]
+    public double X { get; set; }
+
+    [JsonPropertyName("y")]
+    public double Y { get; set; }
+
+    [JsonPropertyName("width")]
+    public double? Width { get; set; }
+
+    [JsonPropertyName("height")]
+    public double? Height { get; set; }
+
+    [JsonPropertyName("angle")]
+    public double? Angle { get; set; }
+
+    [JsonPropertyName("visible")]
+    public bool? Visible { get; set; }
+
+    /// <summary>业务数据（节点配置）。替代旧 WorkflowNode.Config 字符串字段。</summary>
+    [JsonPropertyName("data")]
+    public JsonElement? Data { get; set; }
+
+    /// <summary>显示名（对应旧 WorkflowNode.Name）。</summary>
+    public string? GetTitle() => Data.TryGetString("title");
+
+    [JsonPropertyName("ports")]
+    public JsonElement? Ports { get; set; }
+}
+
+/// <summary>
+/// X6 边。source/target 用 { cell, port } 结构；几何信息（vertices/router/connector）放顶层；
+/// 业务字段（edgeType/condition/order）放 data。
+/// </summary>
+public sealed class GraphEdge
+{
+    [JsonPropertyName("id")]
+    public string Id { get; set; } = string.Empty;
+
+    [JsonPropertyName("shape")]
+    public string? Shape { get; set; }
+
+    [JsonPropertyName("source")]
+    public GraphEndpoint Source { get; set; } = new();
+
+    [JsonPropertyName("target")]
+    public GraphEndpoint Target { get; set; } = new();
+
+    /// <summary>业务数据：edgeType / condition / order。</summary>
+    [JsonPropertyName("data")]
+    public JsonElement? Data { get; set; }
+
+    [JsonPropertyName("label")]
+    public JsonElement? Label { get; set; }
+
+    [JsonPropertyName("vertices")]
+    public List<GraphPoint>? Vertices { get; set; }
+
+    [JsonPropertyName("router")]
+    public JsonElement? Router { get; set; }
+
+    [JsonPropertyName("connector")]
+    public JsonElement? Connector { get; set; }
+
+    /// <summary>边类型（Normal=0/Approved=1/Rejected=2）。缺省为 Normal。</summary>
+    public EdgeType GetEdgeType() => Data.TryGetInt32("edgeType") is { } v ? (EdgeType)v : EdgeType.Normal;
+
+    /// <summary>条件表达式（Condition/ExclusiveGateway 出边）。</summary>
+    public string? GetCondition() => Data.TryGetString("condition");
+
+    /// <summary>分支评估顺序（值小优先）。</summary>
+    public int GetOrder() => Data.TryGetInt32("order") ?? 0;
+}
+
+public sealed class GraphEndpoint
+{
+    /// <summary>节点 id（对应 GraphNode.Id）。</summary>
+    [JsonPropertyName("cell")]
+    public string? Cell { get; set; }
+
+    /// <summary>端口 id（top/right/bottom/left）。</summary>
+    [JsonPropertyName("port")]
+    public string? Port { get; set; }
+}
+
+public sealed class GraphPoint
+{
+    [JsonPropertyName("x")]
+    public double X { get; set; }
+
+    [JsonPropertyName("y")]
+    public double Y { get; set; }
+}
+
+/// <summary>
+/// JsonElement? 安全取值扩展：统一处理 Nullable 解构与 ValueKind 校验，
+/// 避免 WorkflowGraph 各 getter 重复 null 检查。
+/// </summary>
+internal static class GraphJsonExtensions
+{
+    public static string? TryGetString(this JsonElement? element, string name) =>
+        element is { ValueKind: JsonValueKind.Object } el
+        && el.TryGetProperty(name, out var p)
+        && p.ValueKind == JsonValueKind.String
+            ? p.GetString()
+            : null;
+
+    public static int? TryGetInt32(this JsonElement? element, string name) =>
+        element is { ValueKind: JsonValueKind.Object } el
+        && el.TryGetProperty(name, out var p)
+        && (p.ValueKind == JsonValueKind.Number || p.ValueKind == JsonValueKind.String)
+        && p.TryGetInt32(out var n)
+            ? n
+            : null;
+}
diff --git a/src/modules/workflow/Domain/Engine/WorkflowShapeMap.cs b/src/modules/workflow/Domain/Engine/WorkflowShapeMap.cs
new file mode 100644
index 0000000..f4ac9d8
--- /dev/null
+++ b/src/modules/workflow/Domain/Engine/WorkflowShapeMap.cs
@@ -0,0 +1,52 @@
+using Workflow.Domain.Enums;
+
+namespace Workflow.Domain.Engine;
+
+/// <summary>
+/// X6 节点 shape 名 与 <see cref="NodeType"/> 的双向映射。
+/// 前端注册节点与后端反推 NodeType 都以此为准。新增 NodeType 必须同步登记 shape。
+/// </summary>
+public static class WorkflowShapeMap
+{
+    /// <summary>shape 名常量，与前端 register 的 shape 一一对应。</summary>
+    public static class Shapes
+    {
+        public const string Start = "wf-start";
+        public const string End = "wf-end";
+        public const string Approval = "wf-approval";
+        public const string Cc = "wf-cc";
+        public const string Condition = "wf-condition";
+        public const string Parallel = "wf-parallel";
+        public const string SubProcess = "wf-subprocess";
+        public const string Timer = "wf-timer";
+        public const string Exclusive = "wf-exclusive";
+        public const string Edge = "wf-edge";
+    }
+
+    private static readonly IReadOnlyDictionary<string, NodeType> ShapeToType = new Dictionary<string, NodeType>(StringComparer.OrdinalIgnoreCase)
+    {
+        [Shapes.Start] = NodeType.Start,
+        [Shapes.End] = NodeType.End,
+        [Shapes.Approval] = NodeType.Approval,
+        [Shapes.Cc] = NodeType.Cc,
+        [Shapes.Condition] = NodeType.Condition,
+        [Shapes.Parallel] = NodeType.Parallel,
+        [Shapes.SubProcess] = NodeType.SubProcess,
+        [Shapes.Timer] = NodeType.Timer,
+        [Shapes.Exclusive] = NodeType.ExclusiveGateway,
+    };
+
+    private static readonly IReadOnlyDictionary<NodeType, string> TypeToShape =
+        ShapeToType.ToDictionary(kv => kv.Value, kv => kv.Key);
+
+    /// <summary>shape 名反推 NodeType；未知 shape 返回 null（发布校验会拦截）。</summary>
+    public static NodeType? ToNodeType(string? shape) =>
+        shape is not null && ShapeToType.TryGetValue(shape, out var t) ? t : null;
+
+    /// <summary>NodeType 转 shape 名。</summary>
+    public static string ToShape(NodeType type) => TypeToShape[type];
+
+    /// <summary>判断 shape 是否为已登记的合法节点 shape。</summary>
+    public static bool IsValidNodeShape(string? shape) =>
+        shape is not null && ShapeToType.ContainsKey(shape);
+}
diff --git a/src/modules/workflow/Domain/Entities/WorkflowDefinitionSnapshot.cs b/src/modules/workflow/Domain/Entities/WorkflowDefinitionSnapshot.cs
new file mode 100644
index 0000000..c57a5bc
--- /dev/null
+++ b/src/modules/workflow/Domain/Entities/WorkflowDefinitionSnapshot.cs
@@ -0,0 +1,34 @@
+using BuildFlow.Shared.Domain.Common;
+
+namespace Workflow.Domain.Entities;
+
+/// <summary>
+/// 工作流定义的发布版本快照。每次发布（Draft → Published）写入一条不可变快照，
+/// ProcessEngine 运行时按 DefinitionId + Version 读快照而非主表当前 DefinitionJson，
+/// 实现「已发布定义不可变 + 运行实例版本隔离」。
+/// 参照仓库已有的 <see cref="FormDefinitionVersion"/> 范式。
+/// </summary>
+public class WorkflowDefinitionSnapshot : BaseEntity, IAuditable
+{
+    /// <summary>所属流程定义 ID。</summary>
+    public Guid DefinitionId { get; set; }
+
+    /// <summary>版本号（与发布时的 WorkflowDefinition.Version 对应）。</summary>
+    public int Version { get; set; }
+
+    /// <summary>该版本的完整 X6 graph JSON 快照（不可变）。引擎运行时唯一事实源。</summary>
+    public string? DefinitionJson { get; set; }
+
+    /// <summary>触发来源：Publish（仅发布写入）。</summary>
+    public string Source { get; set; } = "Publish";
+
+    /// <summary>变更摘要（可选）。</summary>
+    public string? ChangeSummary { get; set; }
+
+    public string CreatedBy { get; set; } = default!;
+    public DateTime CreatedAt { get; set; } = DateTime.UtcNow;
+    public string UpdatedBy { get; set; } = default!;
+    public DateTime UpdatedAt { get; set; } = DateTime.UtcNow;
+    public bool IsDeleted { get; set; }
+    public string OperatorIP { get; set; } = "unknown";
+}
diff --git a/src/modules/workflow/Domain/Entities/WorkflowInstance.cs b/src/modules/workflow/Domain/Entities/WorkflowInstance.cs
index 8194b4b..06982e7 100644
--- a/src/modules/workflow/Domain/Entities/WorkflowInstance.cs
+++ b/src/modules/workflow/Domain/Entities/WorkflowInstance.cs
@@ -11,6 +11,11 @@ namespace Workflow.Domain.Entities;
 public class WorkflowInstance : BaseEntity, IFullAudit
 {
     public Guid DefinitionId { get; set; }
+    /// <summary>实例启动时绑定的流程定义版本号。ProcessEngine 按 DefinitionId + DefinitionVersion 读不可变快照，
+    /// 避免已发布定义被新版覆盖后污染运行中实例（版本隔离）。</summary>
+    public int DefinitionVersion { get; set; } = 1;
+    /// <summary>实例启动时快照的流程定义 Code，便于追溯（运行时不读，仅审计用）。</summary>
+    public string? DefinitionCode { get; set; }
     public string Title { get; set; } = string.Empty;
     public InstanceStatus Status { get; set; } = InstanceStatus.Running;
     /// <summary>流程变量（JSON 字符串）。条件节点求值、节点动作钩子均从此读取运行时数据。</summary>
diff --git a/src/modules/workflow/Infrastructure/Persistence/Configurations/WorkflowDefinitionSnapshotConfiguration.cs b/src/modules/workflow/Infrastructure/Persistence/Configurations/WorkflowDefinitionSnapshotConfiguration.cs
new file mode 100644
index 0000000..b5f4e17
--- /dev/null
+++ b/src/modules/workflow/Infrastructure/Persistence/Configurations/WorkflowDefinitionSnapshotConfiguration.cs
@@ -0,0 +1,35 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Metadata.Builders;
+using Workflow.Domain.Entities;
+
+namespace Workflow.Infrastructure.Persistence.Configurations;
+
+/// <summary>
+/// 工作流定义发布快照表映射配置。每次发布生成一条不可变快照，支撑引擎版本隔离。
+/// 参照仓库已有的 <see cref="FormDefinitionVersionConfiguration"/> 范式。
+/// </summary>
+public class WorkflowDefinitionSnapshotConfiguration : IEntityTypeConfiguration<WorkflowDefinitionSnapshot>
+{
+    public void Configure(EntityTypeBuilder<WorkflowDefinitionSnapshot> builder)
+    {
+        builder.ToTable("wf_workflow_definition_snapshots");
+
+        builder.HasKey(e => e.Id);
+        builder.Property(e => e.Id).ValueGeneratedNever().HasComment("主键ID");
+        builder.Property(e => e.DefinitionId).HasComment("所属工作流定义ID");
+        builder.Property(e => e.Version).HasComment("版本号（发布时的 WorkflowDefinition.Version）");
+        builder.Property(e => e.DefinitionJson).HasColumnType("jsonb").HasComment("该版本的完整X6 graph JSON快照（不可变）");
+        builder.Property(e => e.Source).HasMaxLength(50).HasComment("触发来源 Publish");
+        builder.Property(e => e.ChangeSummary).HasMaxLength(1000).HasComment("变更摘要");
+        builder.Property(e => e.CreatedBy).HasMaxLength(100).HasComment("创建人ID");
+        builder.Property(e => e.CreatedAt).HasComment("创建时间");
+        builder.Property(e => e.UpdatedBy).HasMaxLength(100).HasComment("更新人ID");
+        builder.Property(e => e.UpdatedAt).HasComment("更新时间");
+        builder.Property(e => e.IsDeleted).HasDefaultValue(false).HasComment("是否软删除");
+        builder.Property(e => e.OperatorIP).HasMaxLength(500).HasComment("操作人IP地址");
+
+        // 复合唯一索引：同一定义同版本仅一条快照
+        builder.HasIndex(e => new { e.DefinitionId, e.Version }).IsUnique();
+        builder.HasIndex(e => e.DefinitionId);
+    }
+}
diff --git a/tests/BuildFlow.File.Tests/DeleteFileCommandHandlerTests.cs b/tests/BuildFlow.File.Tests/DeleteFileCommandHandlerTests.cs
index efbab7e..a656bfa 100644
--- a/tests/BuildFlow.File.Tests/DeleteFileCommandHandlerTests.cs
+++ b/tests/BuildFlow.File.Tests/DeleteFileCommandHandlerTests.cs
@@ -1,5 +1,6 @@
 using BuildFlow.Shared.Domain.Common;
 using BuildFlow.Shared.Infrastructure;
+using File.Application.Common;
 using File.Application.Features.Files.Commands;
 using File.Application.Features.Files.Handlers;
 using File.Domain.Entities;
@@ -21,6 +22,14 @@ public class DeleteFileCommandHandlerTests
     private const string Bucket = "build-flow";
     private const string Key = "multipart/abc123";
 
+    /// <summary>测试用 bucket 解析器，固定返回与 <see cref="Bucket"/> 一致的桶名。</summary>
+    private static IBucketResolver BucketResolver()
+    {
+        var mock = new Mock<IBucketResolver>();
+        mock.Setup(r => r.GetDefaultBucketAsync(It.IsAny<CancellationToken>())).ReturnsAsync(Bucket);
+        return mock.Object;
+    }
+
     /// <summary>构造测试依赖：InMemory DB（挂审计拦截器自动填充非空字段）+ Mock S3 + Mock Mediator。</summary>
     private static (FileDbContext db, Mock<IS3StorageService> s3, Mock<MediatR.IMediator> mediator) CreateDeps(string dbName)
     {
@@ -57,10 +66,10 @@ public class DeleteFileCommandHandlerTests
         db.Files.Add(NewMeta(Bucket, Key));
         await db.SaveChangesAsync();
 
-        var handler = new DeleteFileCommandHandler(s3.Object, db, mediator.Object);
+        var handler = new DeleteFileCommandHandler(s3.Object, db, BucketResolver(), mediator.Object);
 
         // Act
-        await handler.Handle(new DeleteFileCommand(Bucket, Key), CancellationToken.None);
+        await handler.Handle(new DeleteFileCommand(Key), CancellationToken.None);
 
         // Assert：S3 对象已删
         s3.Verify(x => x.DeleteFileAsync(Bucket, Key, It.IsAny<CancellationToken>()), Times.Once);
@@ -74,10 +83,10 @@ public class DeleteFileCommandHandlerTests
     {
         // Arrange：DB 无匹配记录（如根目录直传未落库、或已被其他途径清理）
         var (db, s3, mediator) = CreateDeps(nameof(Delete_无FileMeta记录_仍删S3对象_不报错));
-        var handler = new DeleteFileCommandHandler(s3.Object, db, mediator.Object);
+        var handler = new DeleteFileCommandHandler(s3.Object, db, BucketResolver(), mediator.Object);
 
         // Act
-        await handler.Handle(new DeleteFileCommand(Bucket, Key), CancellationToken.None);
+        await handler.Handle(new DeleteFileCommand(Key), CancellationToken.None);
 
         // Assert：S3 仍尝试删除（幂等，删不存在的对象也返回成功）
         s3.Verify(x => x.DeleteFileAsync(Bucket, Key, It.IsAny<CancellationToken>()), Times.Once);
@@ -92,10 +101,10 @@ public class DeleteFileCommandHandlerTests
         db.Files.Add(NewMeta(Bucket, Key, "user-002"));
         await db.SaveChangesAsync();
 
-        var handler = new DeleteFileCommandHandler(s3.Object, db, mediator.Object);
+        var handler = new DeleteFileCommandHandler(s3.Object, db, BucketResolver(), mediator.Object);
 
         // Act
-        await handler.Handle(new DeleteFileCommand(Bucket, Key), CancellationToken.None);
+        await handler.Handle(new DeleteFileCommand(Key), CancellationToken.None);
 
         // Assert：两条记录都被清理
         var remaining = await db.Files.Where(f => f.S3Bucket == Bucket && f.S3Key == Key).ToListAsync();
@@ -111,10 +120,10 @@ public class DeleteFileCommandHandlerTests
         db.Files.Add(NewMeta(Bucket, "multipart/bbb"));
         await db.SaveChangesAsync();
 
-        var handler = new DeleteFileCommandHandler(s3.Object, db, mediator.Object);
+        var handler = new DeleteFileCommandHandler(s3.Object, db, BucketResolver(), mediator.Object);
 
         // Act：只删 aaa
-        await handler.Handle(new DeleteFileCommand(Bucket, "multipart/aaa"), CancellationToken.None);
+        await handler.Handle(new DeleteFileCommand("multipart/aaa"), CancellationToken.None);
 
         // Assert：aaa 没了，bbb 还在
         var remaining = await db.Files.ToListAsync();
@@ -132,10 +141,10 @@ public class DeleteFileCommandHandlerTests
         s3.Setup(x => x.DeleteFileAsync(Bucket, Key, It.IsAny<CancellationToken>()))
           .ThrowsAsync(new Exception("S3 连接失败"));
 
-        var handler = new DeleteFileCommandHandler(s3.Object, db, mediator.Object);
+        var handler = new DeleteFileCommandHandler(s3.Object, db, BucketResolver(), mediator.Object);
 
         // Act
-        var act = () => handler.Handle(new DeleteFileCommand(Bucket, Key), CancellationToken.None);
+        var act = () => handler.Handle(new DeleteFileCommand(Key), CancellationToken.None);
 
         // Assert：异常向上抛
         await act.Should().ThrowAsync<Exception>().WithMessage("S3 连接失败");
@@ -149,10 +158,10 @@ public class DeleteFileCommandHandlerTests
     {
         // Arrange
         var (db, s3, mediator) = CreateDeps(nameof(Delete_发布FileDeletedEvent));
-        var handler = new DeleteFileCommandHandler(s3.Object, db, mediator.Object);
+        var handler = new DeleteFileCommandHandler(s3.Object, db, BucketResolver(), mediator.Object);
 
         // Act
-        await handler.Handle(new DeleteFileCommand(Bucket, Key), CancellationToken.None);
+        await handler.Handle(new DeleteFileCommand(Key), CancellationToken.None);
 
         // Assert：事件已发布（供其他模块响应，如清理缓存）
         mediator.Verify(
diff --git a/tests/BuildFlow.File.Tests/DownloadFileQueryHandlerTests.cs b/tests/BuildFlow.File.Tests/DownloadFileQueryHandlerTests.cs
index c504fa1..2ff96b1 100644
--- a/tests/BuildFlow.File.Tests/DownloadFileQueryHandlerTests.cs
+++ b/tests/BuildFlow.File.Tests/DownloadFileQueryHandlerTests.cs
@@ -1,4 +1,5 @@
 using System.Text;
+using File.Application.Common;
 using File.Application.Features.Files.Handlers;
 using File.Application.Features.Files.Queries;
 using File.Infrastructure.Storage;
@@ -14,6 +15,14 @@ namespace BuildFlow.File.Tests;
 /// </summary>
 public class DownloadFileQueryHandlerTests
 {
+    /// <summary>测试用 bucket 解析器，固定返回 "test-bucket"。</summary>
+    private static IBucketResolver BucketResolver()
+    {
+        var mock = new Mock<IBucketResolver>();
+        mock.Setup(r => r.GetDefaultBucketAsync(It.IsAny<CancellationToken>())).ReturnsAsync("test-bucket");
+        return mock.Object;
+    }
+
     /// <summary>创建 Mock S3 + Handler。</summary>
     private static (Mock<IS3StorageService> s3Mock, DownloadFileQueryHandler handler) Setup(string content = "hello world")
     {
@@ -23,7 +32,7 @@ public class DownloadFileQueryHandlerTests
             .Setup(x => x.DownloadFileAsync("test-bucket", "test-key", It.IsAny<CancellationToken>()))
             .ReturnsAsync((stream, "text/plain"));
 
-        var handler = new DownloadFileQueryHandler(s3Mock.Object);
+        var handler = new DownloadFileQueryHandler(s3Mock.Object, BucketResolver());
         return (s3Mock, handler);
     }
 
@@ -35,7 +44,7 @@ public class DownloadFileQueryHandlerTests
 
         // Act
         var result = await handler.Handle(
-            new DownloadFileQuery("test-bucket", "test-key"),
+            new DownloadFileQuery("test-key"),
             CancellationToken.None);
 
         // Assert — 返回的是 S3 原始流，透传给调用方；ContentType 取 S3 返回的真实类型
@@ -56,11 +65,11 @@ public class DownloadFileQueryHandlerTests
             .Setup(x => x.DownloadFileAsync(It.IsAny<string>(), It.IsAny<string>(), It.IsAny<CancellationToken>()))
             .ReturnsAsync((emptyStream, "application/octet-stream"));
 
-        var handler = new DownloadFileQueryHandler(s3Mock.Object);
+        var handler = new DownloadFileQueryHandler(s3Mock.Object, BucketResolver());
 
         // Act
         var result = await handler.Handle(
-            new DownloadFileQuery("test-bucket", "test-key"),
+            new DownloadFileQuery("test-key"),
             CancellationToken.None);
 
         // Assert — Handler 透传空流，长度为 0
diff --git a/tests/BuildFlow.File.Tests/InstantUploadTests.cs b/tests/BuildFlow.File.Tests/InstantUploadTests.cs
index 4be51fa..5401527 100644
--- a/tests/BuildFlow.File.Tests/InstantUploadTests.cs
+++ b/tests/BuildFlow.File.Tests/InstantUploadTests.cs
@@ -1,5 +1,6 @@
 using BuildFlow.Shared.Domain.Common;
 using BuildFlow.Shared.Infrastructure;
+using File.Application.Common;
 using File.Application.Features.Multipart.Commands;
 using File.Application.Features.Multipart.DTOs;
 using File.Application.Features.Multipart.Handlers;
@@ -23,6 +24,15 @@ public class InstantUploadTests
 {
     private const string OwnerId = "user-001";
     private const string Sha = "2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824";
+    private const string Bucket = "files";
+
+    /// <summary>测试用 bucket 解析器，固定返回与 <see cref="Bucket"/> 一致的桶名。</summary>
+    private static IBucketResolver BucketResolver()
+    {
+        var mock = new Mock<IBucketResolver>();
+        mock.Setup(r => r.GetDefaultBucketAsync(It.IsAny<CancellationToken>())).ReturnsAsync(Bucket);
+        return mock.Object;
+    }
 
     private static (FileDbContext db, Mock<IS3StorageService> s3, Mock<ICurrentUserContext> user) CreateDeps(string dbName)
     {
@@ -49,9 +59,9 @@ public class InstantUploadTests
         });
         await db.SaveChangesAsync();
 
-        var handler = new InitMultipartCommandHandler(s3.Object, db, user.Object);
+        var handler = new InitMultipartCommandHandler(s3.Object, db, user.Object, BucketResolver());
 
-        var result = await handler.Handle(new InitMultipartCommand("files", "obj", Sha, TotalParts: 1, Size: 1024), CancellationToken.None);
+        var result = await handler.Handle(new InitMultipartCommand("obj", Sha, TotalParts: 1, Size: 1024), CancellationToken.None);
 
         result.Instant.Should().BeTrue("同用户同哈希同大小应命中秒传");
         result.UploadId.Should().BeEmpty("秒传不需要 uploadId");
@@ -73,9 +83,9 @@ public class InstantUploadTests
         });
         await db.SaveChangesAsync();
         s3.Setup(x => x.CreateMultipartUploadAsync("files", "obj", default)).ReturnsAsync("uid-1");
-        var handler = new InitMultipartCommandHandler(s3.Object, db, user.Object);
+        var handler = new InitMultipartCommandHandler(s3.Object, db, user.Object, BucketResolver());
 
-        var result = await handler.Handle(new InitMultipartCommand("files", "obj", Sha, TotalParts: 1, Size: 2048), CancellationToken.None);
+        var result = await handler.Handle(new InitMultipartCommand("obj", Sha, TotalParts: 1, Size: 2048), CancellationToken.None);
 
         result.Instant.Should().BeFalse("大小不同不应命中秒传");
         result.UploadId.Should().Be("uid-1");
@@ -93,9 +103,9 @@ public class InstantUploadTests
         });
         await db.SaveChangesAsync();
         s3.Setup(x => x.CreateMultipartUploadAsync(It.IsAny<string>(), It.IsAny<string>(), It.IsAny<CancellationToken>())).ReturnsAsync("uid-1");
-        var handler = new InitMultipartCommandHandler(s3.Object, db, user.Object);
+        var handler = new InitMultipartCommandHandler(s3.Object, db, user.Object, BucketResolver());
 
-        var result = await handler.Handle(new InitMultipartCommand("files", "obj", Sha, TotalParts: 1, Size: 1024), CancellationToken.None);
+        var result = await handler.Handle(new InitMultipartCommand("obj", Sha, TotalParts: 1, Size: 1024), CancellationToken.None);
 
         result.Instant.Should().BeFalse("他人文件不参与当前用户秒传");
     }
@@ -117,9 +127,9 @@ public class InstantUploadTests
         {
             new(1, "etag-1"), new(2, "etag-2"),
         };
-        var handler = new CompleteMultipartCommandHandler(s3.Object, db, user.Object);
+        var handler = new CompleteMultipartCommandHandler(s3.Object, db, user.Object, BucketResolver());
 
-        var result = await handler.Handle(new CompleteMultipartCommand("files", "obj-key", "uid-1", parts, FileName: "a.bin", Size: 1024), CancellationToken.None);
+        var result = await handler.Handle(new CompleteMultipartCommand("obj-key", "uid-1", parts, FileName: "a.bin", Size: 1024), CancellationToken.None);
 
         result.Location.Should().Be("files/obj-key");
         // FileMeta 应被创建
@@ -135,8 +145,8 @@ public class InstantUploadTests
         session.Status.Should().Be(UploadSessionStatus.Completed);
 
         // 串联验证：再次 init 同文件现在能命中秒传
-        var initHandler = new InitMultipartCommandHandler(s3.Object, db, user.Object);
-        var initResult = await initHandler.Handle(new InitMultipartCommand("files", "obj2", Sha, TotalParts: 2, Size: 1024), CancellationToken.None);
+        var initHandler = new InitMultipartCommandHandler(s3.Object, db, user.Object, BucketResolver());
+        var initResult = await initHandler.Handle(new InitMultipartCommand("obj2", Sha, TotalParts: 2, Size: 1024), CancellationToken.None);
         initResult.Instant.Should().BeTrue("FileMeta 已落库，再次分片上传同文件应秒传");
     }
 }
diff --git a/tests/BuildFlow.File.Tests/MultipartUploadSessionTests.cs b/tests/BuildFlow.File.Tests/MultipartUploadSessionTests.cs
index 901effa..526192e 100644
--- a/tests/BuildFlow.File.Tests/MultipartUploadSessionTests.cs
+++ b/tests/BuildFlow.File.Tests/MultipartUploadSessionTests.cs
@@ -1,6 +1,7 @@
 using BuildFlow.Shared.Domain.Common;
 using BuildFlow.Shared.Domain.Exceptions;
 using BuildFlow.Shared.Infrastructure;
+using File.Application.Common;
 using File.Application.Features.Multipart.Commands;
 using File.Application.Features.Multipart.DTOs;
 using File.Application.Features.Multipart.Handlers;
@@ -23,6 +24,15 @@ namespace BuildFlow.File.Tests;
 public class MultipartUploadSessionTests
 {
     private const string OwnerId = "user-001";
+    private const string Bucket = "bk";
+
+    /// <summary>测试用 bucket 解析器，固定返回与预置会话一致的桶名 "bk"。</summary>
+    private static IBucketResolver BucketResolver()
+    {
+        var mock = new Mock<IBucketResolver>();
+        mock.Setup(r => r.GetDefaultBucketAsync(It.IsAny<CancellationToken>())).ReturnsAsync(Bucket);
+        return mock.Object;
+    }
 
     /// <summary>
     /// 构造一组注入了 InMemory DbContext 的 handler 依赖。
@@ -63,9 +73,9 @@ public class MultipartUploadSessionTests
     {
         var (db, s3, user) = CreateDeps(nameof(Init_首次_发起S3Init并落库会话));
         s3.Setup(x => x.CreateMultipartUploadAsync("bk", "key", default)).ReturnsAsync("upload-1");
-        var handler = new InitMultipartCommandHandler(s3.Object, db, user.Object);
+        var handler = new InitMultipartCommandHandler(s3.Object, db, user.Object, BucketResolver());
 
-        var result = await handler.Handle(new InitMultipartCommand("bk", "key", "hash-abc", TotalParts: 3), CancellationToken.None);
+        var result = await handler.Handle(new InitMultipartCommand("key", "hash-abc", TotalParts: 3), CancellationToken.None);
 
         result.UploadId.Should().Be("upload-1");
         result.Resume.Should().BeFalse();
@@ -85,9 +95,9 @@ public class MultipartUploadSessionTests
 
         s3.Setup(x => x.CreateMultipartUploadAsync(It.IsAny<string>(), It.IsAny<string>(), It.IsAny<CancellationToken>()))
           .ReturnsAsync("upload-new"); // 不应被调用
-        var handler = new InitMultipartCommandHandler(s3.Object, db, user.Object);
+        var handler = new InitMultipartCommandHandler(s3.Object, db, user.Object, BucketResolver());
 
-        var result = await handler.Handle(new InitMultipartCommand("bk", "key"), CancellationToken.None);
+        var result = await handler.Handle(new InitMultipartCommand("key"), CancellationToken.None);
 
         result.UploadId.Should().Be("upload-existing");
         result.Resume.Should().BeTrue();
@@ -102,7 +112,7 @@ public class MultipartUploadSessionTests
         var (db, s3, user) = CreateDeps(nameof(UploadPart_会话不存在_抛NotFound));
         var handler = new UploadPartCommandHandler(s3.Object, db, user.Object);
 
-        var act = () => handler.Handle(new UploadPartCommand("bk", "key", "no-such", 1, new MemoryStream([1])), CancellationToken.None);
+        var act = () => handler.Handle(new UploadPartCommand("key", "no-such", 1, new MemoryStream([1])), CancellationToken.None);
 
         await act.Should().ThrowAsync<NotFoundException>();
         s3.Verify(x => x.UploadPartAsync(It.IsAny<string>(), It.IsAny<string>(), It.IsAny<string>(), It.IsAny<int>(), It.IsAny<Stream>(), It.IsAny<CancellationToken>()), Times.Never);
@@ -116,7 +126,7 @@ public class MultipartUploadSessionTests
         await db.SaveChangesAsync();
         var handler = new UploadPartCommandHandler(s3.Object, db, user.Object);
 
-        var act = () => handler.Handle(new UploadPartCommand("bk", "key", "upload-other", 1, new MemoryStream([1])), CancellationToken.None);
+        var act = () => handler.Handle(new UploadPartCommand("key", "upload-other", 1, new MemoryStream([1])), CancellationToken.None);
 
         // 他人会话也报 NotFound，不泄露存在性
         await act.Should().ThrowAsync<NotFoundException>();
@@ -130,7 +140,7 @@ public class MultipartUploadSessionTests
         await db.SaveChangesAsync();
         var handler = new UploadPartCommandHandler(s3.Object, db, user.Object);
 
-        var act = () => handler.Handle(new UploadPartCommand("bk", "key", "upload-done", 1, new MemoryStream([1])), CancellationToken.None);
+        var act = () => handler.Handle(new UploadPartCommand("key", "upload-done", 1, new MemoryStream([1])), CancellationToken.None);
 
         await act.Should().ThrowAsync<ConflictException>();
     }
@@ -141,10 +151,10 @@ public class MultipartUploadSessionTests
         var (db, s3, user) = CreateDeps(nameof(Complete_成功后会话标记Completed));
         db.UploadSessions.Add(NewSession("bk", "key", "upload-1", OwnerId));
         await db.SaveChangesAsync();
-        var handler = new CompleteMultipartCommandHandler(s3.Object, db, user.Object);
+        var handler = new CompleteMultipartCommandHandler(s3.Object, db, user.Object, BucketResolver());
         var parts = new List<CompletedPartDto> { new(1, "etag-1") };
 
-        var result = await handler.Handle(new CompleteMultipartCommand("bk", "key", "upload-1", parts), CancellationToken.None);
+        var result = await handler.Handle(new CompleteMultipartCommand("key", "upload-1", parts), CancellationToken.None);
 
         result.Location.Should().Be("bk/key");
         s3.Verify(x => x.CompleteMultipartUploadAsync("bk", "key", "upload-1", It.IsAny<List<CompletedPart>>(), It.IsAny<CancellationToken>()), Times.Once);
@@ -160,7 +170,7 @@ public class MultipartUploadSessionTests
         await db.SaveChangesAsync();
         var handler = new AbortMultipartCommandHandler(s3.Object, db, user.Object);
 
-        await handler.Handle(new AbortMultipartCommand("bk", "key", "upload-1"), CancellationToken.None);
+        await handler.Handle(new AbortMultipartCommand("key", "upload-1"), CancellationToken.None);
 
         s3.Verify(x => x.AbortMultipartUploadAsync("bk", "key", "upload-1", It.IsAny<CancellationToken>()), Times.Once);
         var session = await db.UploadSessions.SingleAsync();
diff --git a/tests/BuildFlow.File.Tests/UploadFileCommandHandlerTests.cs b/tests/BuildFlow.File.Tests/UploadFileCommandHandlerTests.cs
index 5d9a357..13329a8 100644
--- a/tests/BuildFlow.File.Tests/UploadFileCommandHandlerTests.cs
+++ b/tests/BuildFlow.File.Tests/UploadFileCommandHandlerTests.cs
@@ -1,5 +1,6 @@
 using BuildFlow.Shared.Domain.Common;
 using BuildFlow.Shared.Infrastructure;
+using File.Application.Common;
 using File.Application.Features.Files.Commands;
 using File.Application.Features.Files.Handlers;
 using File.Domain.Entities;
@@ -21,6 +22,14 @@ public class UploadFileCommandHandlerTests
     private const string OwnerId = "user-001";
     private const string Sha = "2cf24dba5fb0a30e26e83b2ac5b9e29e1b161e5c1fa7425e73043362938b9824";
 
+    /// <summary>测试用 bucket 解析器，固定返回 "files"。</summary>
+    private static IBucketResolver BucketResolver(string bucket = "files")
+    {
+        var mock = new Mock<IBucketResolver>();
+        mock.Setup(r => r.GetDefaultBucketAsync(It.IsAny<CancellationToken>())).ReturnsAsync(bucket);
+        return mock.Object;
+    }
+
     private static (FileDbContext db, Mock<IS3StorageService> s3, Mock<ICurrentUserContext> user) CreateDeps(string dbName)
     {
         var user = new Mock<ICurrentUserContext>();
@@ -40,10 +49,10 @@ public class UploadFileCommandHandlerTests
         // 缺陷C核心：直传必须落 FileMeta，否则直传的文件永远无法被秒传
         var (db, s3, user) = CreateDeps(nameof(Upload_成功后落FileMeta_含ContentHash_使直传参与秒传));
         var data = new MemoryStream([1, 2, 3]);
-        var handler = new UploadFileCommandHandler(s3.Object, db, user.Object, new Mock<MediatR.IMediator>().Object);
+        var handler = new UploadFileCommandHandler(s3.Object, db, user.Object, BucketResolver(), new Mock<MediatR.IMediator>().Object);
 
         var result = await handler.Handle(
-            new UploadFileCommand("files", "obj-key", data, "application/octet-stream", 3, Sha),
+            new UploadFileCommand("obj-key", data, "application/octet-stream", 3, Sha),
             CancellationToken.None);
 
         result.ObjectKey.Should().Be("obj-key");
@@ -63,10 +72,10 @@ public class UploadFileCommandHandlerTests
     public async Task Upload_超过500MiB_抛TooLarge()
     {
         var (db, s3, user) = CreateDeps(nameof(Upload_超过500MiB_抛TooLarge));
-        var handler = new UploadFileCommandHandler(s3.Object, db, user.Object, new Mock<MediatR.IMediator>().Object);
+        var handler = new UploadFileCommandHandler(s3.Object, db, user.Object, BucketResolver(), new Mock<MediatR.IMediator>().Object);
 
         var act = () => handler.Handle(
-            new UploadFileCommand("files", "big", new MemoryStream(), "application/octet-stream", 501 * 1024 * 1024),
+            new UploadFileCommand("big", new MemoryStream(), "application/octet-stream", 501 * 1024 * 1024),
             CancellationToken.None);
 
         await act.Should().ThrowAsync<TooLargeException>();
@@ -84,10 +93,10 @@ public class UploadFileCommandHandlerTests
             Size = 3, ContentType = "application/octet-stream", ContentHash = Sha, OwnerId = OwnerId,
         });
         await db.SaveChangesAsync();
-        var handler = new UploadFileCommandHandler(s3.Object, db, user.Object, new Mock<MediatR.IMediator>().Object);
+        var handler = new UploadFileCommandHandler(s3.Object, db, user.Object, BucketResolver(), new Mock<MediatR.IMediator>().Object);
 
         await handler.Handle(
-            new UploadFileCommand("files", "obj-key", new MemoryStream([1, 2, 3]), "application/octet-stream", 3, Sha),
+            new UploadFileCommand("obj-key", new MemoryStream([1, 2, 3]), "application/octet-stream", 3, Sha),
             CancellationToken.None);
 
         // 仍只有一条记录