diff --git a/backend-rewrite-tasklist/01_M0_M2_FOUNDATION_AND_AUTH.md b/backend-rewrite-tasklist/01_M0_M2_FOUNDATION_AND_AUTH.md
index 922dbf70..cf63bc89 100644
--- a/backend-rewrite-tasklist/01_M0_M2_FOUNDATION_AND_AUTH.md
+++ b/backend-rewrite-tasklist/01_M0_M2_FOUNDATION_AND_AUTH.md
@@ -102,7 +102,8 @@
   交付物：[../server-rs/apps/api-server/src/http_error.rs](../server-rs/apps/api-server/src/http_error.rs)、[../server-rs/apps/api-server/src/error_middleware.rs](../server-rs/apps/api-server/src/error_middleware.rs)、[../server-rs/apps/api-server/src/app.rs](../server-rs/apps/api-server/src/app.rs)
 - [x] 接入当前项目兼容的 response envelope
   交付物：[../server-rs/apps/api-server/src/api_response.rs](../server-rs/apps/api-server/src/api_response.rs)、[../server-rs/apps/api-server/src/request_context.rs](../server-rs/apps/api-server/src/request_context.rs)、[../server-rs/apps/api-server/src/http_error.rs](../server-rs/apps/api-server/src/http_error.rs)
-- [ ] 接入 `x-request-id`
+- [x] 接入 `x-request-id`
+  交付物：[../server-rs/apps/api-server/src/response_headers.rs](../server-rs/apps/api-server/src/response_headers.rs)、[../server-rs/apps/api-server/src/app.rs](../server-rs/apps/api-server/src/app.rs)
 - [ ] 接入 `x-api-version`
 - [ ] 接入 `x-route-version`
 - [ ] 接入 `x-response-time-ms`
diff --git a/server-rs/apps/api-server/README.md b/server-rs/apps/api-server/README.md
index 3c70c48b..0891e816 100644
--- a/server-rs/apps/api-server/README.md
+++ b/server-rs/apps/api-server/README.md
@@ -43,7 +43,7 @@
 
 1. 中间件优先读取来访 `x-request-id`，未提供时生成新的 UUID。
 2. `request_id` 会统一写入请求 `extensions` 与请求头，供 tracing、错误处理中间件和响应头层复用。
-3. 响应头回写 `x-request-id` 仍属于后续独立任务，本阶段只完成请求上下文准备。
+3. 最终响应会回写同一个 `x-request-id`，保证调用方、日志链路和后续 envelope `meta.requestId` 可对齐。
 
 当前错误处理中间件约定：
 
diff --git a/server-rs/apps/api-server/src/app.rs b/server-rs/apps/api-server/src/app.rs
index 8abffd7e..e1f8dbc8 100644
--- a/server-rs/apps/api-server/src/app.rs
+++ b/server-rs/apps/api-server/src/app.rs
@@ -5,6 +5,7 @@ use tracing::{info_span, Level};
 use crate::{
     error_middleware::normalize_error_response,
     request_context::{attach_request_context, resolve_request_id},
+    response_headers::propagate_request_id_header,
     state::AppState,
 };
 
@@ -13,6 +14,8 @@ pub fn build_router(state: AppState) -> Router {
     Router::new()
         // 错误归一化层放在 tracing 里侧，让 tracing 记录到最终对外返回的状态与错误体形态。
         .layer(middleware::from_fn(normalize_error_response))
+        // 响应头回写放在错误归一化外侧，确保最终写回的是归一化后的最终响应。
+        .layer(middleware::from_fn(propagate_request_id_header))
         // 当前阶段先统一挂接 HTTP tracing，后续 request_id、响应头与错误中间件继续在这里扩展。
         .layer(
             TraceLayer::new_for_http()
diff --git a/server-rs/apps/api-server/src/main.rs b/server-rs/apps/api-server/src/main.rs
index ba69c81e..6f840e8c 100644
--- a/server-rs/apps/api-server/src/main.rs
+++ b/server-rs/apps/api-server/src/main.rs
@@ -5,6 +5,7 @@ mod error_middleware;
 mod http_error;
 mod logging;
 mod request_context;
+mod response_headers;
 mod state;
 
 use tokio::net::TcpListener;
diff --git a/server-rs/apps/api-server/src/response_headers.rs b/server-rs/apps/api-server/src/response_headers.rs
new file mode 100644
index 00000000..ca95909b
--- /dev/null
+++ b/server-rs/apps/api-server/src/response_headers.rs
@@ -0,0 +1,23 @@
+use axum::{
+    extract::Request,
+    http::{header::HeaderName, HeaderValue},
+    middleware::Next,
+    response::Response,
+};
+
+use crate::request_context::{resolve_request_id, X_REQUEST_ID_HEADER};
+
+pub async fn propagate_request_id_header(request: Request, next: Next) -> Response {
+    let request_id = resolve_request_id(&request);
+    let mut response = next.run(request).await;
+
+    if let Some(request_id) = request_id {
+        if let Ok(header_value) = HeaderValue::from_str(&request_id) {
+            response
+                .headers_mut()
+                .insert(HeaderName::from_static(X_REQUEST_ID_HEADER), header_value);
+        }
+    }
+
+    response
+}