feat: add FileAccessDownloadToken entity and migration

- Introduced the FileAccessDownloadToken entity with properties for managing file access tokens.
- Created a migration to add the file_access_download_tokens table to the database with appropriate constraints and indexes.

.env.example

@@ -3,6 +3,7 @@ ConnectionStrings__Default=Host=localhost;Database=member_center;Username=postgr
 Auth__Issuer=http://localhost:7850/
 Auth__WebLoginUrl=http://localhost:5080/account/login
 Auth__AllowedLoginReturnUrlPrefixes=http://localhost:7850/
+Auth__AllowedLogoutReturnUrlPrefixes=http://localhost:5243/
 Auth__MemberCenterAudience=member_center_api
 Auth__SendEngineAudience=send_engine_api
 SendEngine__BaseUrl=http://localhost:6060

docs/DESIGN.md

@@ -79,6 +79,8 @@
   - id, email, tenant_id, token_hash, purpose, expires_at, consumed_at
 - unsubscribe_tokens
   - id, subscription_id, token_hash, expires_at, consumed_at
+- file_access_download_tokens
+  - id, token_hash, tenant_id, user_id, file_id, object_key, method, scope, issued_by_client_id, expires_at, revoked_at, last_validated_at, created_at
 - audit_logs
   - id, actor_type, actor_id, action, payload, created_at
 - system_flags
@@ -196,17 +198,16 @@
    - access agent 以 JWKS 驗簽 JWT，並驗 `iss/aud/exp/scope/tenant_id`
 2) Download 採 delegated short-lived token：
    - client 向 `A service` 要求下載
-   - `A service` 驗商業規則與檔案權限
-   - `A service` 向新 File Access 專案取得短效 download token，或由 File Access 專案提供簽發元件
+   - `A service` 以自己的商業邏輯驗證 Member Center user 身份與檔案權限
+   - `A service` 以 `files:download.delegate` 向 Member Center 申請短效 download token
    - client 帶短效 token 直接向 access agent / file space 請求檔案
-   - access agent 驗 token 後放行
+   - access agent 以 `files:download.read` 回打 Member Center 驗證 token 與實際 GET request 邊界一致後放行
 
 規則：
 - 不直接將一般 S2S access token 暴露給 client 作為下載 token
 - download token 應至少帶：
-  - `aud=file_access_api`
-  - `scope=files:download.read`
   - `tenant_id`
+  - `user_id`
   - `file_id` 或 `object_key`
   - `method=GET`
   - 短效 `exp`
@@ -216,11 +217,7 @@
   - `scope=files:upload.write`
   - `tenant_id`
 - access agent 應驗：
-  - JWT signature（JWKS）
-  - `iss`
-  - `aud`
-  - `exp`
-  - `scope`
+  - Member Center validation endpoint 回傳 `active=true`
   - `tenant_id`
   - 檔案識別與 method 是否與 token 一致
 
@@ -256,7 +253,7 @@ resource registry 至少需定義：
 設計原則：
 - resource registry 由 DB 與管理 UI 管理非敏感欄位
 - `TokenController` 依 scope 與 usage 對照 resource registry 計算 resources / audiences
-- delegated token 與一般 S2S token 共用同一套 resource registry，不重複維護 audience 規則
+- delegated download token 由 Member Center 簽發與線上驗證；一般 S2S token 仍由 resource registry 決定 audience
 - 對外資料讀寫授權完全由 scope 決定，只要 client 被授權該 scope 即可存取對應能力
 
 目前實作狀態：
@@ -264,7 +261,7 @@ resource registry 至少需定義：
 - 預設 seed 已包含 `member_center_api`、`send_engine_api`、`file_access_api`
 - OAuth client usage-scope matrix 已由 DB 驅動，包含 `file_api`
 - resource registry 管理 UI 仍待補
-- delegated download token 發放流程不放在 Member Center，會在新 File Access 專案實作
+- delegated download token issuing / validation 已由 Member Center API 負責，File Access agent 以 validation endpoint 確認 client GET request 帶來的 token 是否有效
 
 ## 7. API 介面（草案）
 - GET `/oauth/authorize`
@@ -321,7 +318,7 @@ resource registry 至少需定義：
 - token 內含 `tenant_id` 與 scope
 - Send Engine 收到租戶請求後以 JWKS 驗簽 JWT（JWS）
 - 驗簽通過後將 `tenant_id` 固定在 request context，不接受 body 覆寫
-- File Access 與未來外部服務亦沿用此模型；File Access 的 delegated token 規則由新 File Access 專案處理
+- File Access 與未來外部服務亦沿用此模型；File Access delegated download token 由 Member Center 簽發與線上驗證
 - 若其他服務要讀取會員個資，應只授予必要的 profile read scopes，不應沿用過寬的 `profile` OIDC scope
 - service API 為主要整合模式，存取控制以 scopes 為唯一授權來源
 
@@ -331,7 +328,7 @@ resource registry 至少需定義：
 - `subscription.linked_to_user` 事件已發送
 - 安全設定頁（access/refresh 時效）目前僅存值，尚未實際套用到 OpenIddict token lifetime
 - Audit Logs 目前以查詢為主，關鍵操作的寫入覆蓋率仍不足
-- resource registry 已完成 DB 驅動第一版；file access delegated token issuing 不屬於 Member Center，會在新專案實作
+- resource registry 已完成 DB 驅動第一版；file access delegated token issuing / validation 已由 Member Center API 實作
 
 ## 8. 安全與合規
 - 密碼強度與防暴力破解（rate limit + lockout）

docs/FLOWS.md

@@ -18,6 +18,13 @@
 - [UI] 若 Web 與 API 不同 origin，需設定 `Auth:WebLoginUrl`，且 Web 端需允許導回 `Auth:Issuer` 或 `Auth:AllowedLoginReturnUrlPrefixes`
 - [UI] 若 Web 與 API 位於不同子網域，需設定 `Auth:CookieDomain`，讓 authorize endpoint 可讀取 Web login cookie
 
+## F-02a 登出（外站 direct logout）
+- [UI] 外站將瀏覽器導向 Member Center Web `/account/logout`
+- [UI] Member Center 清除 Web login cookie / session
+- [UI] 若帶 `returnUrl`，Member Center 僅允許導回本站 local URL 或 allowlist 內的外站 URL
+- [UI] 登出完成後導回外站 callback
+- [UI] 外站 callback 清除本站 session / token
+
 ## F-02b 內容站台呼叫 Send Engine（Client Credentials + JWT 驗簽）
 - [API] 內容站台以 `client_credentials` 呼叫 `POST /oauth/token` 取得 access_token（`usage=send_api`）
 - [API] 內容站台帶 Bearer token 呼叫 Send Engine 建立發送任務
@@ -33,12 +40,12 @@
 
 ## F-02d 檔案下載（A service -> client -> File Space）
 - [API] client 向 `A service` 請求下載檔案
-- [API] `A service` 驗證該 request 是否可讀取指定檔案
-- [API] `A service` 向新 File Access 專案取得短效 download token，或使用 File Access 專案提供的簽發元件
-- [API] download token 需至少綁定 `tenant_id + file_id/object_key + method=GET + exp`
+- [API] `A service` 以自己的商業邏輯驗證該 user 是否可讀取指定檔案
+- [API] `A service` 以 `files:download.delegate` 呼叫 Member Center `POST /file-access/download-tokens` 取得短效 download token
+- [API] download token 由 Member Center 簽發，至少綁定 `tenant_id + user_id + file_id/object_key + method=GET + exp`
 - [UI/API] `A service` 將帶短效 token 的下載 URL 回給 client
 - [UI/API] client 直接向 access agent / file space 請求檔案
-- [API] access agent 驗 token 後放行
+- [API] access agent 以 `files:download.read` 呼叫 Member Center `POST /file-access/download-tokens/validate`，確認 token 與實際 GET request 邊界一致後放行
 
 註記：下載流程不直接暴露一般 S2S token 給 client。
 

docs/MEMBER_UPGRADE_PLAN.md

@@ -163,7 +163,7 @@
 - `MemberCenter.Api` 已有 `GET /user/profile`，但目前只提供基礎欄位，不足以支撐其他服務查詢完整會員資料。
 - `docs/DESIGN.md` / `docs/FLOWS.md` 已定義 File Access 流程：
   - upload: `client_credentials` 取得 upload token 後由外部服務直連 file space
-  - download: 由業務服務驗權後，交由新 File Access 專案簽發或管理短效 delegated download token
+  - download: 由業務服務驗權後，向 Member Center 申請短效 delegated download token，File Access agent 回打 Member Center 驗證
 - Auth resource registry 第一版已落地：
   - 新增 `auth_resources`、`auth_resource_scopes`、`auth_client_usage_permissions`
   - `TokenController` 已改由 scope 查 registry 決定 token audiences
@@ -177,7 +177,7 @@
 - profile / addresses / subscriptions 畫面與驗證目前為最小可用版本，尚未完成 UI refinement。
 
 ### 待補項
-- File Access 的 OAuth client usage、scope、audience 已落地；delegated token 發放流程不放在 Member Center，會在新 File Access 專案實作。
+- File Access 的 OAuth client usage、scope、audience 已落地；delegated download token issuing / validation 已落在 Member Center。
 - Token resource / audience 已抽象為 registry；後續需補 resource registry 管理畫面。
 - Email 樣板正式文案與會員 / 後台 UI 細節仍待整理。
 - rate limit 仍缺少 `one-click unsubscribe token` 與更細的風控觀測。
@@ -628,9 +628,10 @@
   - `files:metadata.read`
 - 新增 audience：
   - `file_access_api`
-- File Access 新專案需實作 delegated token 規則：
+- Member Center 需實作 delegated download token 規則：
   - 下載 token 必須短效
   - 必須綁定 `tenant_id`
+  - 必須綁定 `user_id`
   - 必須綁定 `file_id` 或 `object_key`
   - 必須綁定 `method`
   - 不可直接重用一般 S2S access token 給 client
@@ -643,7 +644,7 @@
   - scopes
   - client usages
   - 是否需要 `tenant_id`
-  - 是否允許 delegated token（供 File Access 判斷，不代表 Member Center 負責簽發檔案下載 token）
+  - 是否允許 delegated token（供 Member Center 判斷該 resource 是否可簽發短效下載 token）
 - 新增資源服務時，只擴充 registry 與授權規則，不再修改硬編碼 audience 分支。
 - 所有外部資料存取均以 scope 作為唯一授權依據。
 
@@ -654,13 +655,13 @@
   - `file_api` -> `file_access_api`
 - scope 用於細粒度權限控制。
 - `TokenController` 依 scope 與 usage 對照 resource registry 計算 `resources/audiences`。
-- delegated download token issuing 屬於新 File Access 專案責任；Member Center 只負責發出可呼叫 File Access 的 OAuth access token。
+- delegated download token issuing / validation 屬於 Member Center 責任；File Access agent 負責把 client GET request 的 token 與 `tenant_id + file_id/object_key + method` 帶回 Member Center 驗證。
 
 目前進度：
 - Send Engine、Member Center profile/newsletter scopes、File Access scopes 已進 registry
 - `TokenController` 已以 registry 解析 audiences
 - OAuth client usage-scope matrix 已以 `auth_client_usage_permissions` 驅動
-- File Access delegated token issuing、流程測試與 sample code 會在新 File Access 專案實作
+- File Access delegated token issuing / validation API 已落在 Member Center；File Access agent 尚需串接 validation endpoint
 
 ### 9. 審計紀錄
 狀態：`大致完成，少數治理事件待續作`
@@ -768,13 +769,13 @@
 ### API
 - 若設定畫面走 API，需新增設定讀寫端點。
 - 若帳號管理後台走 API，需新增角色管理與帳號查詢端點。
-- File Access 的 resource / audience mapping 與 file scopes 已完成；流程測試與 sample code 會在新 File Access 專案實作。
+- File Access 的 resource / audience mapping、file scopes、delegated token issuing / validation API 已完成；File Access agent 串接與流程測試仍待補。
 - 需新增 current-user 型 profile / addresses / subscriptions API 與對應 scopes。
 
 ### Infrastructure
 - 新增 SMTP sender 與設定存取服務。
 - 調整帳號 provisioning 與角色管理服務。
-- token resource resolver 已抽到 registry service；File Access delegated token issuer 不屬於 Member Center。
+- token resource resolver 已抽到 registry service；File Access delegated token issuer / validator 已落在 Member Center。
 - 新增會員基本資料與地址簿的資料模型與服務層。
 
 ### Installer

docs/OPENAPI.md

@@ -162,28 +162,26 @@
   - access agent 驗 `iss/aud/exp/scope/tenant_id`
 - Download 採 delegated short-lived token：
   - 不直接將一般 S2S token 暴露給 client
+  - `A service` 先以自身商業邏輯驗證 Member Center user 身份與檔案權限
+  - `A service` 以 `files:download.delegate` 向 Member Center 申請短效 download token
+  - access agent 以 `files:download.read` 回打 Member Center 驗證 token 是否有效
   - 下載 token 至少需帶：
-    - `aud=file_access_api`
-    - `scope=files:download.read`
     - `tenant_id`
+    - `user_id`
     - `file_id` 或 `object_key`
     - `method=GET`
     - 短效 `exp`
     - 建議 `jti`
-- access agent 至少應驗：
-  - JWT signature（JWKS）
-  - `iss`
-  - `aud`
-  - `exp`
-  - `scope`
+- access agent 至少應送回 Member Center 驗：
+  - opaque download token
   - `tenant_id`
   - token 內檔案識別與實際 request 是否一致
   - token 內 method 與實際 request 是否一致
 
 補充：
 - File Access 與 Send Engine 同屬「外部資源服務」，驗證模型一致
-- 差異在於 File Access download token 為 delegated short-lived token，而非一般 client credentials token
-- delegated download token issuing、流程測試與 sample code 會在新 File Access 專案實作，不屬於 Member Center API
+- 差異在於 File Access download token 為 Member Center 簽發的 delegated short-lived opaque token，而非一般 client credentials token
+- Member Center 負責 delegated download token issuing 與 validation；File Access agent 負責把實際 GET request 的 tenant/file/method 邊界帶回 Member Center 驗證
 
 ### 回寫原因碼（Send Engine -> Member Center）
 - `hard_bounce`

docs/TEST_SITE.md

@@ -22,6 +22,7 @@ http://localhost:5243
 {
   "MemberCenter": {
     "ApiBaseUrl": "http://localhost:7850",
+    "WebBaseUrl": "http://localhost:5080",
     "WebLoginClientId": "<web_login client id>",
     "ServiceClientId": "<service client id>",
     "ServiceClientSecret": "<service client secret>"
@@ -45,6 +46,7 @@ service OAuth client：
 ```text
 Auth__WebLoginUrl=<Member Center Web login URL>
 Auth__AllowedLoginReturnUrlPrefixes=<Member Center API issuer/base URL>
+Auth__AllowedLogoutReturnUrlPrefixes=http://localhost:5243/
 Auth__CookieDomain=<shared cookie domain, production subdomain SSO only>
 ```
 
@@ -53,14 +55,15 @@ Auth__CookieDomain=<shared cookie domain, production subdomain SSO only>
 測試站目前包含：
 
 1. Redirect login 拿 token
-2. API login 拿 token
-3. `GET /user/profile`
-4. `POST /user/profile`
-5. `GET /user/addresses`
-6. `POST /user/addresses`
-7. `GET /user/subscriptions`
-8. `POST /user/subscriptions/{id}/unsubscribe`
-9. service token 呼叫 `GET /user/profile/by-email`
-10. service token 呼叫 `GET /user/addresses/by-email`
+2. Redirect logout 清除 Member Center Web session 並回到 TestSite
+3. API login 拿 token
+4. `GET /user/profile`
+5. `POST /user/profile`
+6. `GET /user/addresses`
+7. `POST /user/addresses`
+8. `GET /user/subscriptions`
+9. `POST /user/subscriptions/{id}/unsubscribe`
+10. service token 呼叫 `GET /user/profile/by-email`
+11. service token 呼叫 `GET /user/addresses/by-email`
 
 測試站只做 happy path，不取代完整自動化測試。

docs/UI.md

@@ -43,7 +43,7 @@
 ### 會員端（統一 UI）
 - UC-01 註冊會員: `/account/register`
 - UC-02 登入: `/account/login`
-- UC-03 登出: `POST /account/logout`
+- UC-03 登出: `POST /account/logout`（外站 direct logout 可導向 `GET /account/logout?returnUrl=...`）
 - UC-04 忘記密碼 / 重設密碼: `/account/forgotpassword`, `/account/resetpassword`
 - UC-04.1 已登入修改密碼: `/account/changepassword`
 - UC-05 Email 驗證: `/account/verifyemail?email=...&token=...`

docs/openapi.yaml

@@ -138,7 +138,7 @@ paths:
 
   /auth/logout:
     post:
-      summary: Logout (revoke refresh token)
+      summary: Logout current authenticated session
       security:
         - BearerAuth: []
       requestBody:
@@ -810,6 +810,48 @@ paths:
         '204':
           description: Deleted
 
+  /file-access/download-tokens:
+    post:
+      summary: Issue delegated short-lived file download token
+      description: |
+        Called by a service after it has verified the Member Center user is allowed to download the requested file.
+        Requires `files:download.delegate`.
+      security: [{ BearerAuth: [] }]
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/IssueFileDownloadTokenRequest'
+      responses:
+        '200':
+          description: Token issued
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/FileDownloadTokenResponse'
+
+  /file-access/download-tokens/validate:
+    post:
+      summary: Validate delegated file download token
+      description: |
+        Called by File Access agent with the token from the client GET request and the actual request boundary.
+        Requires `files:download.read`.
+      security: [{ BearerAuth: [] }]
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/ValidateFileDownloadTokenRequest'
+      responses:
+        '200':
+          description: Validation result
+          content:
+            application/json:
+              schema:
+                $ref: '#/components/schemas/FileDownloadTokenValidationResponse'
+
 components:
   securitySchemes:
     OAuth2:
@@ -927,6 +969,52 @@ components:
         token: { type: string }
         new_password: { type: string }
 
+    IssueFileDownloadTokenRequest:
+      type: object
+      required: [tenant_id, user_id]
+      properties:
+        tenant_id: { type: string, format: uuid }
+        user_id: { type: string, format: uuid }
+        file_id: { type: string, nullable: true }
+        object_key: { type: string, nullable: true }
+        method: { type: string, enum: [GET], default: GET }
+        expires_in_seconds: { type: integer, minimum: 30, maximum: 900, default: 300 }
+
+    FileDownloadTokenResponse:
+      type: object
+      properties:
+        token: { type: string }
+        token_type: { type: string, example: file_download }
+        expires_at: { type: string, format: date-time }
+        tenant_id: { type: string, format: uuid }
+        user_id: { type: string, format: uuid }
+        file_id: { type: string, nullable: true }
+        object_key: { type: string, nullable: true }
+        method: { type: string, example: GET }
+        scope: { type: string, example: files:download.read }
+
+    ValidateFileDownloadTokenRequest:
+      type: object
+      required: [token, tenant_id]
+      properties:
+        token: { type: string }
+        tenant_id: { type: string, format: uuid }
+        file_id: { type: string, nullable: true }
+        object_key: { type: string, nullable: true }
+        method: { type: string, enum: [GET], default: GET }
+
+    FileDownloadTokenValidationResponse:
+      type: object
+      properties:
+        active: { type: boolean }
+        tenant_id: { type: string, format: uuid }
+        user_id: { type: string, format: uuid }
+        file_id: { type: string, nullable: true }
+        object_key: { type: string, nullable: true }
+        method: { type: string, example: GET }
+        scope: { type: string, example: files:download.read }
+        expires_at: { type: string, format: date-time }
+
     UserProfile:
       type: object
       properties:

src/MemberCenter.Api/Contracts/FileAccessRequests.cs

@@ -0,0 +1,18 @@
+using System.Text.Json.Serialization;
+
+namespace MemberCenter.Api.Contracts;
+
+public sealed record IssueFileDownloadTokenRequest(
+    [property: JsonPropertyName("tenant_id")] Guid TenantId,
+    [property: JsonPropertyName("user_id")] Guid UserId,
+    [property: JsonPropertyName("file_id")] string? FileId,
+    [property: JsonPropertyName("object_key")] string? ObjectKey,
+    [property: JsonPropertyName("method")] string? Method,
+    [property: JsonPropertyName("expires_in_seconds")] int? ExpiresInSeconds);
+
+public sealed record ValidateFileDownloadTokenRequest(
+    [property: JsonPropertyName("token")] string Token,
+    [property: JsonPropertyName("tenant_id")] Guid TenantId,
+    [property: JsonPropertyName("file_id")] string? FileId,
+    [property: JsonPropertyName("object_key")] string? ObjectKey,
+    [property: JsonPropertyName("method")] string? Method);

src/MemberCenter.Api/Controllers/FileAccessController.cs

@@ -0,0 +1,204 @@
+using System.Security.Cryptography;
+using System.Text;
+using MemberCenter.Api.Contracts;
+using MemberCenter.Domain.Entities;
+using MemberCenter.Infrastructure.Identity;
+using MemberCenter.Infrastructure.Persistence;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Identity;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.WebUtilities;
+using Microsoft.EntityFrameworkCore;
+using OpenIddict.Abstractions;
+
+namespace MemberCenter.Api.Controllers;
+
+[ApiController]
+[Route("file-access/download-tokens")]
+public sealed class FileAccessController : ControllerBase
+{
+    private const string DownloadScope = "files:download.read";
+    private const string TokenPurpose = "file_access_download";
+    private static readonly TimeSpan DefaultLifetime = TimeSpan.FromMinutes(5);
+    private static readonly TimeSpan MinimumLifetime = TimeSpan.FromSeconds(30);
+    private static readonly TimeSpan MaximumLifetime = TimeSpan.FromMinutes(15);
+
+    private readonly MemberCenterDbContext _dbContext;
+    private readonly UserManager<ApplicationUser> _userManager;
+
+    public FileAccessController(MemberCenterDbContext dbContext, UserManager<ApplicationUser> userManager)
+    {
+        _dbContext = dbContext;
+        _userManager = userManager;
+    }
+
+    [Authorize(Policy = "FilesDownloadDelegate")]
+    [HttpPost("")]
+    public async Task<IActionResult> Issue([FromBody] IssueFileDownloadTokenRequest request)
+    {
+        var validationError = ValidateBoundary(request.TenantId, request.FileId, request.ObjectKey, request.Method);
+        if (validationError is not null)
+        {
+            return BadRequest(validationError);
+        }
+
+        if (!IsTenantAllowed(request.TenantId))
+        {
+            return BadRequest("tenant_id does not match token tenant scope.");
+        }
+
+        if (request.UserId == Guid.Empty)
+        {
+            return BadRequest("user_id is required.");
+        }
+
+        var user = await _userManager.FindByIdAsync(request.UserId.ToString());
+        if (user is null || user.DisabledAt.HasValue)
+        {
+            return BadRequest("user_id is invalid or disabled.");
+        }
+
+        var lifetime = ResolveLifetime(request.ExpiresInSeconds);
+        var expiresAt = DateTimeOffset.UtcNow.Add(lifetime);
+        var token = $"fdt_{WebEncoders.Base64UrlEncode(RandomNumberGenerator.GetBytes(32))}";
+
+        var record = new FileAccessDownloadToken
+        {
+            Id = Guid.NewGuid(),
+            TokenHash = HashToken(token),
+            TenantId = request.TenantId,
+            UserId = request.UserId,
+            FileId = NormalizeOptional(request.FileId),
+            ObjectKey = NormalizeOptional(request.ObjectKey),
+            Method = "GET",
+            Scope = DownloadScope,
+            IssuedByClientId = User.GetClaim(OpenIddictConstants.Claims.ClientId),
+            ExpiresAt = expiresAt
+        };
+
+        _dbContext.FileAccessDownloadTokens.Add(record);
+        await _dbContext.SaveChangesAsync(HttpContext.RequestAborted);
+
+        return Ok(new
+        {
+            token,
+            token_type = "file_download",
+            expires_at = expiresAt,
+            tenant_id = record.TenantId,
+            user_id = record.UserId,
+            file_id = record.FileId,
+            object_key = record.ObjectKey,
+            method = record.Method,
+            scope = record.Scope
+        });
+    }
+
+    [Authorize(Policy = "FilesDownloadRead")]
+    [HttpPost("validate")]
+    public async Task<IActionResult> Validate([FromBody] ValidateFileDownloadTokenRequest request)
+    {
+        var validationError = ValidateBoundary(request.TenantId, request.FileId, request.ObjectKey, request.Method);
+        if (validationError is not null || string.IsNullOrWhiteSpace(request.Token))
+        {
+            return Ok(new { active = false });
+        }
+
+        if (!IsTenantAllowed(request.TenantId))
+        {
+            return Ok(new { active = false });
+        }
+
+        var tokenHash = HashToken(request.Token);
+        var now = DateTimeOffset.UtcNow;
+        var record = await _dbContext.FileAccessDownloadTokens
+            .SingleOrDefaultAsync(token =>
+                token.TokenHash == tokenHash
+                && token.RevokedAt == null
+                && token.ExpiresAt > now,
+                HttpContext.RequestAborted);
+
+        if (record is null
+            || record.TenantId != request.TenantId
+            || !string.Equals(record.Method, "GET", StringComparison.OrdinalIgnoreCase)
+            || !string.Equals(record.FileId, NormalizeOptional(request.FileId), StringComparison.Ordinal)
+            || !string.Equals(record.ObjectKey, NormalizeOptional(request.ObjectKey), StringComparison.Ordinal))
+        {
+            return Ok(new { active = false });
+        }
+
+        var user = await _userManager.FindByIdAsync(record.UserId.ToString());
+        if (user is null || user.DisabledAt.HasValue)
+        {
+            return Ok(new { active = false });
+        }
+
+        record.LastValidatedAt = now;
+        await _dbContext.SaveChangesAsync(HttpContext.RequestAborted);
+
+        return Ok(new
+        {
+            active = true,
+            tenant_id = record.TenantId,
+            user_id = record.UserId,
+            file_id = record.FileId,
+            object_key = record.ObjectKey,
+            method = record.Method,
+            scope = record.Scope,
+            expires_at = record.ExpiresAt
+        });
+    }
+
+    private bool IsTenantAllowed(Guid tenantId)
+    {
+        var tokenTenantId = User.FindFirst("tenant_id")?.Value;
+        return string.IsNullOrWhiteSpace(tokenTenantId)
+            || (Guid.TryParse(tokenTenantId, out var parsed) && parsed == tenantId);
+    }
+
+    private static string? ValidateBoundary(Guid tenantId, string? fileId, string? objectKey, string? method)
+    {
+        if (tenantId == Guid.Empty)
+        {
+            return "tenant_id is required.";
+        }
+
+        if (!string.Equals(method ?? "GET", "GET", StringComparison.OrdinalIgnoreCase))
+        {
+            return "Only method=GET is supported for file download tokens.";
+        }
+
+        if (string.IsNullOrWhiteSpace(fileId) && string.IsNullOrWhiteSpace(objectKey))
+        {
+            return "file_id or object_key is required.";
+        }
+
+        return null;
+    }
+
+    private static TimeSpan ResolveLifetime(int? expiresInSeconds)
+    {
+        if (!expiresInSeconds.HasValue)
+        {
+            return DefaultLifetime;
+        }
+
+        var requested = TimeSpan.FromSeconds(expiresInSeconds.Value);
+        if (requested < MinimumLifetime)
+        {
+            return MinimumLifetime;
+        }
+
+        return requested > MaximumLifetime ? MaximumLifetime : requested;
+    }
+
+    private static string? NormalizeOptional(string? value)
+    {
+        return string.IsNullOrWhiteSpace(value) ? null : value.Trim();
+    }
+
+    private static string HashToken(string token)
+    {
+        var bytes = SHA256.HashData(Encoding.UTF8.GetBytes($"{TokenPurpose}:{token}"));
+        return Convert.ToHexString(bytes).ToLowerInvariant();
+    }
+}

src/MemberCenter.Api/Program.cs

@@ -149,6 +149,8 @@ builder.Services.AddAuthorization(options =>
     options.AddPolicy("ProfileAddressesWrite", policy => policy.RequireAssertion(context => context.User.HasScope("profile:addresses.write")));
     options.AddPolicy("ProfileSubscriptionsRead", policy => policy.RequireAssertion(context => context.User.HasScope("profile:subscriptions.read")));
     options.AddPolicy("ProfileSubscriptionsWrite", policy => policy.RequireAssertion(context => context.User.HasScope("profile:subscriptions.write")));
+    options.AddPolicy("FilesDownloadDelegate", policy => policy.RequireAssertion(context => context.User.HasScope("files:download.delegate")));
+    options.AddPolicy("FilesDownloadRead", policy => policy.RequireAssertion(context => context.User.HasScope("files:download.read")));
 });
 
 builder.Services.Configure<ForwardedHeadersOptions>(options =>

src/MemberCenter.Domain/Entities/FileAccessDownloadToken.cs

@@ -0,0 +1,18 @@
+namespace MemberCenter.Domain.Entities;
+
+public sealed class FileAccessDownloadToken
+{
+    public Guid Id { get; set; }
+    public string TokenHash { get; set; } = string.Empty;
+    public Guid TenantId { get; set; }
+    public Guid UserId { get; set; }
+    public string? FileId { get; set; }
+    public string? ObjectKey { get; set; }
+    public string Method { get; set; } = "GET";
+    public string Scope { get; set; } = "files:download.read";
+    public string? IssuedByClientId { get; set; }
+    public DateTimeOffset ExpiresAt { get; set; }
+    public DateTimeOffset? RevokedAt { get; set; }
+    public DateTimeOffset? LastValidatedAt { get; set; }
+    public DateTimeOffset CreatedAt { get; set; } = DateTimeOffset.UtcNow;
+}

src/MemberCenter.Infrastructure/Persistence/MemberCenterDbContext.cs

@@ -26,6 +26,7 @@ public class MemberCenterDbContext
     public DbSet<AuthResource> AuthResources => Set<AuthResource>();
     public DbSet<AuthResourceScope> AuthResourceScopes => Set<AuthResourceScope>();
     public DbSet<AuthClientUsagePermission> AuthClientUsagePermissions => Set<AuthClientUsagePermission>();
+    public DbSet<FileAccessDownloadToken> FileAccessDownloadTokens => Set<FileAccessDownloadToken>();
 
     protected override void OnModelCreating(ModelBuilder builder)
     {
@@ -245,6 +246,30 @@ public class MemberCenterDbContext
             entity.HasIndex(x => new { x.Usage, x.Scope }).IsUnique();
         });
 
+        builder.Entity<FileAccessDownloadToken>(entity =>
+        {
+            entity.ToTable("file_access_download_tokens");
+            entity.HasKey(x => x.Id);
+            entity.Property(x => x.TokenHash).IsRequired();
+            entity.Property(x => x.FileId).HasMaxLength(200);
+            entity.Property(x => x.ObjectKey).HasMaxLength(1000);
+            entity.Property(x => x.Method).IsRequired().HasMaxLength(10).HasDefaultValue("GET");
+            entity.Property(x => x.Scope).IsRequired().HasMaxLength(200).HasDefaultValue("files:download.read");
+            entity.Property(x => x.IssuedByClientId).HasMaxLength(200);
+            entity.Property(x => x.CreatedAt).HasDefaultValueSql("now()");
+            entity.HasIndex(x => x.TokenHash).IsUnique();
+            entity.HasIndex(x => x.ExpiresAt).HasDatabaseName("idx_file_access_download_tokens_expires_at");
+            entity.HasIndex(x => new { x.TenantId, x.UserId }).HasDatabaseName("idx_file_access_download_tokens_tenant_user");
+            entity.HasOne<Tenant>()
+                .WithMany()
+                .HasForeignKey(x => x.TenantId)
+                .OnDelete(DeleteBehavior.Cascade);
+            entity.HasOne<ApplicationUser>()
+                .WithMany()
+                .HasForeignKey(x => x.UserId)
+                .OnDelete(DeleteBehavior.Cascade);
+        });
+
         builder.Entity<ApplicationUser>(entity =>
         {
             entity.ToTable("users");

src/MemberCenter.Infrastructure/Persistence/Migrations/20260423055404_AddFileAccessDownloadTokens.cs

@@ -0,0 +1,78 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace MemberCenter.Infrastructure.Persistence.Migrations
+{
+    /// <inheritdoc />
+    public partial class AddFileAccessDownloadTokens : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "file_access_download_tokens",
+                columns: table => new
+                {
+                    Id = table.Column<Guid>(type: "uuid", nullable: false),
+                    TokenHash = table.Column<string>(type: "text", nullable: false),
+                    TenantId = table.Column<Guid>(type: "uuid", nullable: false),
+                    UserId = table.Column<Guid>(type: "uuid", nullable: false),
+                    FileId = table.Column<string>(type: "character varying(200)", maxLength: 200, nullable: true),
+                    ObjectKey = table.Column<string>(type: "character varying(1000)", maxLength: 1000, nullable: true),
+                    Method = table.Column<string>(type: "character varying(10)", maxLength: 10, nullable: false, defaultValue: "GET"),
+                    Scope = table.Column<string>(type: "character varying(200)", maxLength: 200, nullable: false, defaultValue: "files:download.read"),
+                    IssuedByClientId = table.Column<string>(type: "character varying(200)", maxLength: 200, nullable: true),
+                    ExpiresAt = table.Column<DateTimeOffset>(type: "timestamp with time zone", nullable: false),
+                    RevokedAt = table.Column<DateTimeOffset>(type: "timestamp with time zone", nullable: true),
+                    LastValidatedAt = table.Column<DateTimeOffset>(type: "timestamp with time zone", nullable: true),
+                    CreatedAt = table.Column<DateTimeOffset>(type: "timestamp with time zone", nullable: false, defaultValueSql: "now()")
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("PK_file_access_download_tokens", x => x.Id);
+                    table.ForeignKey(
+                        name: "FK_file_access_download_tokens_tenants_TenantId",
+                        column: x => x.TenantId,
+                        principalTable: "tenants",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                    table.ForeignKey(
+                        name: "FK_file_access_download_tokens_users_UserId",
+                        column: x => x.UserId,
+                        principalTable: "users",
+                        principalColumn: "Id",
+                        onDelete: ReferentialAction.Cascade);
+                });
+
+            migrationBuilder.CreateIndex(
+                name: "idx_file_access_download_tokens_expires_at",
+                table: "file_access_download_tokens",
+                column: "ExpiresAt");
+
+            migrationBuilder.CreateIndex(
+                name: "idx_file_access_download_tokens_tenant_user",
+                table: "file_access_download_tokens",
+                columns: new[] { "TenantId", "UserId" });
+
+            migrationBuilder.CreateIndex(
+                name: "IX_file_access_download_tokens_TokenHash",
+                table: "file_access_download_tokens",
+                column: "TokenHash",
+                unique: true);
+
+            migrationBuilder.CreateIndex(
+                name: "IX_file_access_download_tokens_UserId",
+                table: "file_access_download_tokens",
+                column: "UserId");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "file_access_download_tokens");
+        }
+    }
+}

src/MemberCenter.Infrastructure/Persistence/Migrations/MemberCenterDbContextModelSnapshot.cs

@@ -251,6 +251,78 @@ namespace MemberCenter.Infrastructure.Persistence.Migrations
                     b.ToTable("email_verifications", (string)null);
                 });
 
+            modelBuilder.Entity("MemberCenter.Domain.Entities.FileAccessDownloadToken", b =>
+                {
+                    b.Property<Guid>("Id")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("uuid");
+
+                    b.Property<DateTimeOffset>("CreatedAt")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("timestamp with time zone")
+                        .HasDefaultValueSql("now()");
+
+                    b.Property<DateTimeOffset>("ExpiresAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<string>("FileId")
+                        .HasMaxLength(200)
+                        .HasColumnType("character varying(200)");
+
+                    b.Property<string>("IssuedByClientId")
+                        .HasMaxLength(200)
+                        .HasColumnType("character varying(200)");
+
+                    b.Property<DateTimeOffset?>("LastValidatedAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<string>("Method")
+                        .IsRequired()
+                        .ValueGeneratedOnAdd()
+                        .HasMaxLength(10)
+                        .HasColumnType("character varying(10)")
+                        .HasDefaultValue("GET");
+
+                    b.Property<string>("ObjectKey")
+                        .HasMaxLength(1000)
+                        .HasColumnType("character varying(1000)");
+
+                    b.Property<DateTimeOffset?>("RevokedAt")
+                        .HasColumnType("timestamp with time zone");
+
+                    b.Property<string>("Scope")
+                        .IsRequired()
+                        .ValueGeneratedOnAdd()
+                        .HasMaxLength(200)
+                        .HasColumnType("character varying(200)")
+                        .HasDefaultValue("files:download.read");
+
+                    b.Property<Guid>("TenantId")
+                        .HasColumnType("uuid");
+
+                    b.Property<string>("TokenHash")
+                        .IsRequired()
+                        .HasColumnType("text");
+
+                    b.Property<Guid>("UserId")
+                        .HasColumnType("uuid");
+
+                    b.HasKey("Id");
+
+                    b.HasIndex("ExpiresAt")
+                        .HasDatabaseName("idx_file_access_download_tokens_expires_at");
+
+                    b.HasIndex("TokenHash")
+                        .IsUnique();
+
+                    b.HasIndex("UserId");
+
+                    b.HasIndex("TenantId", "UserId")
+                        .HasDatabaseName("idx_file_access_download_tokens_tenant_user");
+
+                    b.ToTable("file_access_download_tokens", (string)null);
+                });
+
             modelBuilder.Entity("MemberCenter.Domain.Entities.NewsletterList", b =>
                 {
                     b.Property<Guid>("Id")
@@ -500,14 +572,14 @@ namespace MemberCenter.Infrastructure.Persistence.Migrations
                     b.HasIndex("UserId")
                         .HasDatabaseName("idx_user_addresses_user_id");
 
-                    b.HasIndex("UserId", "Usage")
-                        .HasDatabaseName("idx_user_addresses_user_id_usage");
-
                     b.HasIndex("UserId", "IsDefault")
                         .IsUnique()
                         .HasDatabaseName("ux_user_addresses_default_per_user")
                         .HasFilter("\"IsDefault\" = true");
 
+                    b.HasIndex("UserId", "Usage")
+                        .HasDatabaseName("idx_user_addresses_user_id_usage");
+
                     b.ToTable("user_addresses", (string)null);
                 });
 
@@ -1042,6 +1114,21 @@ namespace MemberCenter.Infrastructure.Persistence.Migrations
                         .IsRequired();
                 });
 
+            modelBuilder.Entity("MemberCenter.Domain.Entities.FileAccessDownloadToken", b =>
+                {
+                    b.HasOne("MemberCenter.Domain.Entities.Tenant", null)
+                        .WithMany()
+                        .HasForeignKey("TenantId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+
+                    b.HasOne("MemberCenter.Infrastructure.Identity.ApplicationUser", null)
+                        .WithMany()
+                        .HasForeignKey("UserId")
+                        .OnDelete(DeleteBehavior.Cascade)
+                        .IsRequired();
+                });
+
             modelBuilder.Entity("MemberCenter.Domain.Entities.NewsletterList", b =>
                 {
                     b.HasOne("MemberCenter.Domain.Entities.Tenant", "Tenant")

src/MemberCenter.TestSite/Controllers/HomeController.cs

@@ -102,6 +102,32 @@ public class HomeController : Controller
         return RedirectToAction(nameof(Index));
     }
 
+    [HttpPost("auth/logout")]
+    public IActionResult Logout()
+    {
+        var options = GetOptions();
+        var callbackUrl = Url.ActionLink(nameof(LogoutCallback), "Home");
+        HttpContext.Session.Remove(UserAccessTokenKey);
+        HttpContext.Session.Remove(UserRefreshTokenKey);
+
+        if (string.IsNullOrWhiteSpace(callbackUrl))
+        {
+            StoreResult("Redirect logout", "Unable to build logout callback URL.");
+            return RedirectToAction(nameof(Index));
+        }
+
+        return Redirect($"{TrimSlash(options.WebBaseUrl)}/account/logout?returnUrl={Uri.EscapeDataString(callbackUrl)}");
+    }
+
+    [HttpGet("auth/logout-callback")]
+    public IActionResult LogoutCallback()
+    {
+        HttpContext.Session.Remove(UserAccessTokenKey);
+        HttpContext.Session.Remove(UserRefreshTokenKey);
+        StoreResult("Redirect logout", "Member Center session cleared and TestSite user tokens removed.");
+        return RedirectToAction(nameof(Index));
+    }
+
     [HttpPost("auth/api-login")]
     public async Task<IActionResult> ApiLogin(string email, string password)
     {

src/MemberCenter.TestSite/Models/MemberCenterTestOptions.cs

@@ -3,8 +3,10 @@ namespace MemberCenter.TestSite.Models;
 public sealed class MemberCenterTestOptions
 {
     public string ApiBaseUrl { get; set; } = "http://localhost:7850";
+    public string WebBaseUrl { get; set; } = "http://localhost:5080";
     public string WebLoginClientId { get; set; } = string.Empty;
     public string WebLoginRedirectPath { get; set; } = "/auth/callback";
+    public string WebLogoutRedirectPath { get; set; } = "/auth/logout-callback";
     public string WebLoginScopes { get; set; } = "openid email profile profile:basic.read profile:basic.write profile:addresses.read profile:addresses.write profile:subscriptions.read profile:subscriptions.write";
     public string ServiceClientId { get; set; } = string.Empty;
     public string ServiceClientSecret { get; set; } = string.Empty;

src/MemberCenter.TestSite/Views/Home/Index.cshtml

@@ -23,6 +23,8 @@
     <dl>
       <dt>API Base URL</dt>
       <dd>@Model.Options.ApiBaseUrl</dd>
+      <dt>Web Base URL</dt>
+      <dd>@Model.Options.WebBaseUrl</dd>
       <dt>web_login Client ID</dt>
       <dd>@(string.IsNullOrWhiteSpace(Model.Options.WebLoginClientId) ? "not configured" : Model.Options.WebLoginClientId)</dd>
       <dt>Service Client ID</dt>
@@ -40,6 +42,9 @@
     <form method="post" asp-action="RedirectLogin">
       <button type="submit">Start Redirect Login</button>
     </form>
+    <form method="post" asp-action="Logout">
+      <button type="submit">Direct Logout</button>
+    </form>
   </article>
 
   <article class="card">

src/MemberCenter.TestSite/appsettings.json

@@ -1,8 +1,10 @@
 {
   "MemberCenter": {
     "ApiBaseUrl": "http://localhost:7850",
+    "WebBaseUrl": "http://localhost:5080",
     "WebLoginClientId": "f48329ef38c54a62b627585a75c9b5d5",
     "WebLoginRedirectPath": "/auth/callback",
+    "WebLogoutRedirectPath": "/auth/logout-callback",
     "WebLoginScopes": "openid email profile profile:basic.read profile:basic.write profile:addresses.read profile:addresses.write profile:subscriptions.read profile:subscriptions.write",
     "ServiceClientId": "e9fe7ae413c54ae49432eca6474648d3",
     "ServiceClientSecret": "To/WaVObQgxCaZwzGexfp/pvUwI2G5o1r55v4sRukYw=",

src/MemberCenter.Web/Controllers/AccountController.cs

@@ -150,12 +150,35 @@ public class AccountController : Controller
         return RedirectToAction("Index", "Home", new { area = string.Empty });
     }
 
+    [HttpGet]
+    public async Task<IActionResult> Logout(string? returnUrl = null)
+    {
+        if (User.Identity?.IsAuthenticated == true)
+        {
+            await _signInManager.SignOutAsync();
+        }
+
+        if (IsAllowedReturnUrl(returnUrl))
+        {
+            return Redirect(returnUrl!);
+        }
+
+        return LocalRedirect("~/");
+    }
+
     [HttpPost]
+    [ActionName("Logout")]
     [Authorize]
     [ValidateAntiForgeryToken]
-    public async Task<IActionResult> Logout()
+    public async Task<IActionResult> LogoutPost(string? returnUrl = null)
     {
         await _signInManager.SignOutAsync();
+
+        if (IsAllowedReturnUrl(returnUrl))
+        {
+            return Redirect(returnUrl!);
+        }
+
         return LocalRedirect("~/");
     }
 
@@ -372,6 +395,8 @@ public class AccountController : Controller
         allowedPrefixes.Add(_configuration["Auth:Issuer"]);
         allowedPrefixes.AddRange((_configuration["Auth:AllowedLoginReturnUrlPrefixes"] ?? string.Empty)
             .Split(',', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries));
+        allowedPrefixes.AddRange((_configuration["Auth:AllowedLogoutReturnUrlPrefixes"] ?? string.Empty)
+            .Split(',', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries));
 
         return allowedPrefixes
             .Where(prefix => !string.IsNullOrWhiteSpace(prefix))