diff --git a/src/BuildFlow.Host/Endpoints/file/Folders/GetRootFilesEndpoint.cs b/src/BuildFlow.Host/Endpoints/file/Folders/GetRootFilesEndpoint.cs
new file mode 100644
index 0000000..2676647
--- /dev/null
+++ b/src/BuildFlow.Host/Endpoints/file/Folders/GetRootFilesEndpoint.cs
@@ -0,0 +1,22 @@
+using File.Application.Features.Folders.DTOs;
+using File.Application.Features.Folders.Queries;
+using MediatR;
+
+namespace BuildFlow.Host.Endpoints.file.Folders;
+
+/// <summary>
+/// 查询根级文件端点。GET /api/files/root，
+/// 返回当前用户 FolderId=null 的所有 FileMeta，使根目录与子文件夹共享同一数据源（DB）。
+/// 注意：路径用 /files/root 而非 /folders/root/files，避免与 POST /folders/{FolderId}/files 模板冲突。
+/// </summary>
+[Authorize]
+public class GetRootFilesEndpoint(IMediator mediator) : Endpoint<EmptyRequest, List<FileMetaDto>>
+{
+    public override void Configure() => Get("/files/root");
+
+    public override async Task HandleAsync(EmptyRequest req, CancellationToken ct)
+    {
+        var result = await mediator.Send(new GetRootFilesQuery(), ct);
+        await Send.OkAsync(result, ct);
+    }
+}
diff --git a/src/modules/file/Application/Features/Folders/Handlers/GetRootFilesQueryHandler.cs b/src/modules/file/Application/Features/Folders/Handlers/GetRootFilesQueryHandler.cs
new file mode 100644
index 0000000..140c025
--- /dev/null
+++ b/src/modules/file/Application/Features/Folders/Handlers/GetRootFilesQueryHandler.cs
@@ -0,0 +1,28 @@
+using BuildFlow.Shared.Domain.Common;
+using File.Application.Features.Folders.DTOs;
+using File.Application.Features.Folders.Queries;
+using File.Infrastructure.Persistence;
+using MediatR;
+using Microsoft.EntityFrameworkCore;
+
+namespace File.Application.Features.Folders.Handlers;
+
+/// <summary>
+/// 查询根级文件处理器。返回当前用户名下 FolderId=null 的所有 FileMeta（按名称排序）。
+/// 与 GetFolderQueryHandler 配合，使根目录与子文件夹共享同一数据源（DB），而非 S3 列表。
+/// </summary>
+public class GetRootFilesQueryHandler(FileDbContext db, ICurrentUserContext currentUser)
+    : IRequestHandler<GetRootFilesQuery, List<FileMetaDto>>
+{
+    public async Task<List<FileMetaDto>> Handle(GetRootFilesQuery req, CancellationToken ct)
+    {
+        var owner = currentUser.GetRequiredUserId();
+        var files = await db.Files
+            .Where(f => f.FolderId == null && f.OwnerId == owner)
+            .OrderBy(f => f.Name)
+            .ToListAsync(ct);
+
+        return files.Select(f => new FileMetaDto(f.Id, f.FolderId, f.Name, f.S3Key, f.S3Bucket,
+            f.Size, f.ContentType, f.OwnerId, f.CreatedAt, f.UpdatedAt)).ToList();
+    }
+}
diff --git a/src/modules/file/Application/Features/Folders/Queries/GetRootFilesQuery.cs b/src/modules/file/Application/Features/Folders/Queries/GetRootFilesQuery.cs
new file mode 100644
index 0000000..30d0552
--- /dev/null
+++ b/src/modules/file/Application/Features/Folders/Queries/GetRootFilesQuery.cs
@@ -0,0 +1,10 @@
+using File.Application.Features.Folders.DTOs;
+using MediatR;
+
+namespace File.Application.Features.Folders.Queries;
+
+/// <summary>
+/// 查询根级文件（FolderId=null 的 FileMeta）。
+/// 根目录和子文件夹统一从 DB 查，避免与 S3 扁平列表数据源冲突。
+/// </summary>
+public record GetRootFilesQuery : IRequest<List<FileMetaDto>>;
diff --git a/src/modules/platform/Infrastructure/Persistence/SeedData.cs b/src/modules/platform/Infrastructure/Persistence/SeedData.cs
index 7223f59..407db95 100644
--- a/src/modules/platform/Infrastructure/Persistence/SeedData.cs
+++ b/src/modules/platform/Infrastructure/Persistence/SeedData.cs
@@ -36,8 +36,9 @@ public static class SeedData
             var userRoleId = Guid.Parse("20000000-0000-0000-0000-000000000003");
 
             var allPerms = await db.Permissions.ToListAsync();
+            // SuperAdmin 与 Admin 均拥有全部权限；User 仅拥有只读权限。
             await db.RolePermissions.AddRangeAsync(allPerms.Select(p => new RolePermission { RoleId = superAdminRoleId, PermissionId = p.Id }));
-            await db.RolePermissions.AddRangeAsync(allPerms.Where(p => p.Code is "user:read" or "user:create" or "user:update" or "role:read" or "permission:read").Select(p => new RolePermission { RoleId = adminRoleId, PermissionId = p.Id }));
+            await db.RolePermissions.AddRangeAsync(allPerms.Select(p => new RolePermission { RoleId = adminRoleId, PermissionId = p.Id }));
             await db.RolePermissions.AddRangeAsync(allPerms.Where(p => p.Code is "user:read" or "role:read" or "permission:read").Select(p => new RolePermission { RoleId = userRoleId, PermissionId = p.Id }));
             await db.SaveChangesAsync();
         }
@@ -160,16 +161,10 @@ public static class SeedData
         var adminRoleId = Guid.Parse("20000000-0000-0000-0000-000000000002");
         var userRoleId = Guid.Parse("20000000-0000-0000-0000-000000000003");
 
+        // SuperAdmin 与 Admin 拥有全部权限（动态取全库权限码，避免后续新增权限时遗漏）。
         var allPermissionCodes = await db.Permissions.Select(p => p.Code).ToListAsync();
         await EnsureRolePermissionsAsync(db, superAdminRoleId, allPermissionCodes);
-        await EnsureRolePermissionsAsync(db, adminRoleId, [
-            "user:read",
-            "user:create",
-            "user:update",
-            "role:read",
-            "permission:read",
-            "menu:read"
-        ]);
+        await EnsureRolePermissionsAsync(db, adminRoleId, allPermissionCodes);
         await EnsureRolePermissionsAsync(db, userRoleId, [
             "user:read",
             "role:read",
diff --git a/tests/BuildFlow.IM.Integration.Tests/ChatHubAuthAndHistoryTests.cs b/tests/BuildFlow.IM.Integration.Tests/ChatHubAuthAndHistoryTests.cs
index 532835d..15f4511 100644
--- a/tests/BuildFlow.IM.Integration.Tests/ChatHubAuthAndHistoryTests.cs
+++ b/tests/BuildFlow.IM.Integration.Tests/ChatHubAuthAndHistoryTests.cs
@@ -1,6 +1,7 @@
 using IM.Application.Chat.Queries;
 using IM.Domain.Enums;
 using IM.Infrastructure.Mongo;
+using MongoDB.Entities;
 using Xunit;
 using Microsoft.AspNetCore.SignalR.Client;
 using Microsoft.AspNetCore.SignalR;
@@ -13,7 +14,7 @@ namespace BuildFlow.IM.Integration.Tests;
 /// 权限隔离与消息历史分页用例。
 /// 通过 MediatR 直接驱动查询/命令处理器，并验证 ChatHub 的非法访问会被 query 的鉴权副作用拦截。
 /// </summary>
-[Collection(ImServerCollection.Name)]
+[Xunit.Collection(ImServerCollection.Name)]
 public class ChatHubAuthAndHistoryTests : IAsyncLifetime
 {
     private readonly ImServerFixture _fixture;
@@ -116,8 +117,6 @@ public class ChatHubAuthAndHistoryTests : IAsyncLifetime
     /// <summary>向指定会话连续写入 N 条消息，返回按插入顺序的 ObjectId 列表。</summary>
     private async Task<List<string>> SeedMessagesAsync(Guid conversationId, int count)
     {
-        await using var scope = _fixture.Services.CreateAsyncScope();
-        var mongo = scope.ServiceProvider.GetRequiredService<MongoDbContext>();
         var docs = new List<MessageDocument>();
         var baseTime = DateTime.UtcNow.AddMinutes(-count);
         for (var i = 0; i < count; i++)
@@ -132,8 +131,8 @@ public class ChatHubAuthAndHistoryTests : IAsyncLifetime
                 CreatedAt = baseTime.AddSeconds(i),
             });
         }
-        await mongo.Messages.InsertManyAsync(docs);
-        return docs.Select(d => d.Id).ToList();
+        await DB.Default.SaveAsync(docs);
+        return docs.Select(d => d.ID).ToList();
     }
 
     private static async Task WaitForAsync(Func<bool> condition, TimeSpan? timeout = null)
diff --git a/tests/BuildFlow.IM.Integration.Tests/ChatHubMessagingTests.cs b/tests/BuildFlow.IM.Integration.Tests/ChatHubMessagingTests.cs
index 49c18a1..0d031a0 100644
--- a/tests/BuildFlow.IM.Integration.Tests/ChatHubMessagingTests.cs
+++ b/tests/BuildFlow.IM.Integration.Tests/ChatHubMessagingTests.cs
@@ -1,7 +1,9 @@
 using IM.Application.Chat.DTOs;
 using IM.Domain.Common;
 using IM.Domain.Enums;
+using IM.Infrastructure.Mongo;
 using IM.Infrastructure.Persistence;
+using MongoDB.Entities;
 using Xunit;
 using Microsoft.AspNetCore.SignalR.Client;
 using Microsoft.EntityFrameworkCore;
@@ -12,7 +14,7 @@ namespace BuildFlow.IM.Integration.Tests;
 /// <summary>
 /// ChatHub 消息收发端到端用例。覆盖发送 → 广播 → 落库 → 未读累加的核心闭环。
 /// </summary>
-[Collection(ImServerCollection.Name)]
+[Xunit.Collection(ImServerCollection.Name)]
 public class ChatHubMessagingTests : IAsyncLifetime
 {
     private readonly ImServerFixture _fixture;
@@ -69,15 +71,13 @@ public class ChatHubMessagingTests : IAsyncLifetime
         Assert.Equal(convId, bobReceived!.ConversationId);
         Assert.Equal(ImServerFixture.AliceId, aliceReceived.SenderId);
 
-        // Assert ②：消息正文已落 MongoDB，可按会话查到
-        await using (var scope = _fixture.Services.CreateAsyncScope())
-        {
-            var mongo = scope.ServiceProvider.GetRequiredService<MongoDbContext>();
-            var docs = await mongo.Messages.Find(m => m.ConversationId == convId).ToListAsync();
-            var persisted = Assert.Single(docs);
-            Assert.Equal("hello integration", persisted.Content);
-            Assert.False(persisted.IsRecalled);
-        }
+        // Assert ②：消息正文已落 MongoDB，可按会话查到（MongoDB.Entities 静态 DB.Default）
+        var docs = await DB.Default.Find<MessageDocument>()
+            .Match(m => m.ConversationId == convId)
+            .ExecuteAsync();
+        var persisted = Assert.Single(docs);
+        Assert.Equal("hello integration", persisted.Content);
+        Assert.False(persisted.IsRecalled);
 
         // Assert ③：会话列表摘要已更新（PostgreSQL 冷数据）
         await using (var scope2 = _fixture.Services.CreateAsyncScope())
diff --git a/tests/BuildFlow.IM.Integration.Tests/ChatHubReadAndRecallTests.cs b/tests/BuildFlow.IM.Integration.Tests/ChatHubReadAndRecallTests.cs
index 2daf7f8..2482482 100644
--- a/tests/BuildFlow.IM.Integration.Tests/ChatHubReadAndRecallTests.cs
+++ b/tests/BuildFlow.IM.Integration.Tests/ChatHubReadAndRecallTests.cs
@@ -1,7 +1,9 @@
 using IM.Application.Chat.DTOs;
 using IM.Domain.Common;
 using IM.Domain.Enums;
+using IM.Infrastructure.Mongo;
 using IM.Infrastructure.Persistence;
+using MongoDB.Entities;
 using Xunit;
 using Microsoft.AspNetCore.SignalR.Client;
 using Microsoft.EntityFrameworkCore;
@@ -13,7 +15,7 @@ namespace BuildFlow.IM.Integration.Tests;
 /// 已读回执与消息撤回的端到端用例。
 /// 覆盖：已读双写清零（PG+Redis）并广播、撤回标记 Mongo 并广播、撤回会话摘要更新。
 /// </summary>
-[Collection(ImServerCollection.Name)]
+[Xunit.Collection(ImServerCollection.Name)]
 public class ChatHubReadAndRecallTests : IAsyncLifetime
 {
     private readonly ImServerFixture _fixture;
@@ -111,15 +113,14 @@ public class ChatHubReadAndRecallTests : IAsyncLifetime
         // Act：Alice 撤回自己的消息（在 2 分钟时间窗内）
         await alice.InvokeAsync("RecallMessage", new RecallMessageRequest(convId, messageId!));
 
-        // Assert ①：Mongo 标记撤回
-        await using (var scope = _fixture.Services.CreateAsyncScope())
-        {
-            var mongo = scope.ServiceProvider.GetRequiredService<MongoDbContext>();
-            var doc = await mongo.Messages.Find(m => m.Id == messageId!).FirstOrDefaultAsync();
-            Assert.True(doc.IsRecalled);
-            Assert.Equal(ImServerFixture.AliceId, doc.RecalledBy);
-            Assert.NotNull(doc.RecalledAt);
-        }
+        // Assert ①：Mongo 标记撤回（MongoDB.Entities 静态 DB.Default）
+        var docs = await DB.Default.Find<MessageDocument>()
+            .Match(m => m.ID == messageId!)
+            .ExecuteAsync();
+        var doc = docs.First();
+        Assert.True(doc.IsRecalled);
+        Assert.Equal(ImServerFixture.AliceId, doc.RecalledBy);
+        Assert.NotNull(doc.RecalledAt);
 
         // Assert ②：会话列表摘要更新为撤回提示（因为撤回的恰是最后一条消息）
         await using (var scope2 = _fixture.Services.CreateAsyncScope())
diff --git a/tests/BuildFlow.IM.Integration.Tests/ImServerFixture.cs b/tests/BuildFlow.IM.Integration.Tests/ImServerFixture.cs
index 87ba0ea..7af83c1 100644
--- a/tests/BuildFlow.IM.Integration.Tests/ImServerFixture.cs
+++ b/tests/BuildFlow.IM.Integration.Tests/ImServerFixture.cs
@@ -12,6 +12,7 @@ using Microsoft.IdentityModel.JsonWebTokens;
 using Microsoft.IdentityModel.Tokens;
 using FluentValidation;
 using MongoDB.Driver;
+using MongoDB.Entities;
 using BuildFlow.Shared.Domain.Common;
 using BuildFlow.Shared.Infrastructure;
 using IM.Application.Chat.Commands;
@@ -94,11 +95,9 @@ public sealed class ImServerFixture : IAsyncLifetime
             options.UseNpgsql(PostgresConnection)
                    .AddInterceptors(sp.GetRequiredService<AuditInterceptor>()));
 
-        // —— MongoDB：消息正文 ——
-        var mongoClient = new MongoClient(MongoConnection);
+        // —— MongoDB：消息正文（MongoDB.Entities 静态 DB.Default）——
         var mongoDbName = MongoUrl.Create(MongoConnection).DatabaseName;
-        services.AddSingleton<IMongoClient>(_ => mongoClient);
-        services.AddScoped(_ => new MongoDbContext(mongoClient, mongoDbName));
+        DB.InitAsync(mongoDbName, MongoClientSettings.FromConnectionString(MongoConnection)).GetAwaiter().GetResult();
 
         // —— Redis：在线状态与未读计数的真实实现 ——
         services.AddSingleton<IConnectionMultiplexer>(_ => _redis!);