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 cf63bc89..d98e0b5e 100644
--- a/backend-rewrite-tasklist/01_M0_M2_FOUNDATION_AND_AUTH.md
+++ b/backend-rewrite-tasklist/01_M0_M2_FOUNDATION_AND_AUTH.md
@@ -104,7 +104,8 @@
   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)
 - [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`
+- [x] 接入 `x-api-version`
+  交付物：[../server-rs/apps/api-server/src/response_headers.rs](../server-rs/apps/api-server/src/response_headers.rs)
 - [ ] 接入 `x-route-version`
 - [ ] 接入 `x-response-time-ms`
 - [ ] 实现 `/healthz`
diff --git a/server-rs/apps/api-server/README.md b/server-rs/apps/api-server/README.md
index 0891e816..51dddaf7 100644
--- a/server-rs/apps/api-server/README.md
+++ b/server-rs/apps/api-server/README.md
@@ -57,6 +57,12 @@
 2. `json_success_body(...)` / `json_error_body(...)` 会根据 `x-genarrative-response-envelope` 自动在“裸数据 / 标准 envelope / legacy error + meta”之间切换。
 3. `meta.apiVersion`、`meta.requestId`、`meta.routeVersion`、`meta.operation`、`meta.latencyMs`、`meta.timestamp` 已按当前前端契约生成，响应头回写仍留给后续独立任务。
 
+当前基础响应头约定：
+
+1. 所有响应都会回写 `x-request-id`。
+2. 所有响应都会回写固定的 `x-api-version`，当前值与 body `meta.apiVersion` 保持一致。
+3. `x-route-version` 与 `x-response-time-ms` 仍留在后续独立任务中补齐。
+
 ## 3. 边界约束
 
 1. `api-server` 负责 HTTP、SSE、Cookie、Header、路由与协议装配。
diff --git a/server-rs/apps/api-server/src/response_headers.rs b/server-rs/apps/api-server/src/response_headers.rs
index ca95909b..ba5dc214 100644
--- a/server-rs/apps/api-server/src/response_headers.rs
+++ b/server-rs/apps/api-server/src/response_headers.rs
@@ -5,7 +5,12 @@ use axum::{
     response::Response,
 };
 
-use crate::request_context::{resolve_request_id, X_REQUEST_ID_HEADER};
+use crate::{
+    api_response::API_VERSION,
+    request_context::{resolve_request_id, X_REQUEST_ID_HEADER},
+};
+
+pub const API_VERSION_HEADER: &str = "x-api-version";
 
 pub async fn propagate_request_id_header(request: Request, next: Next) -> Response {
     let request_id = resolve_request_id(&request);
@@ -19,5 +24,11 @@ pub async fn propagate_request_id_header(request: Request, next: Next) -> Respon
         }
     }
 
+    if let Ok(header_value) = HeaderValue::from_str(API_VERSION) {
+        response
+            .headers_mut()
+            .insert(HeaderName::from_static(API_VERSION_HEADER), header_value);
+    }
+
     response
 }