diff --git a/apps/ai-game-creator-shell/src-tauri/src/http_client.rs b/apps/ai-game-creator-shell/src-tauri/src/http_client.rs
new file mode 100644
index 000000000..c4601f1bf
--- /dev/null
+++ b/apps/ai-game-creator-shell/src-tauri/src/http_client.rs
@@ -0,0 +1,120 @@
+use reqwest::header::{HeaderMap, HeaderName, HeaderValue};
+
+const AGC_CLIENT_MARKER_HEADER: &str = "x-genarrative-client";
+const AGC_CLIENT_MARKER_VALUE: &str = "agc";
+
+pub(crate) fn agc_main_site_client_builder() -> reqwest::ClientBuilder {
+    let mut headers = HeaderMap::new();
+    headers.insert(
+        HeaderName::from_static(AGC_CLIENT_MARKER_HEADER),
+        HeaderValue::from_static(AGC_CLIENT_MARKER_VALUE),
+    );
+    reqwest::Client::builder().default_headers(headers)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{agc_main_site_client_builder, AGC_CLIENT_MARKER_HEADER, AGC_CLIENT_MARKER_VALUE};
+    use reqwest::header::AUTHORIZATION;
+    use std::io::{Read, Write};
+    use std::net::{TcpListener, TcpStream};
+    use std::time::Duration;
+
+    fn read_http_request(stream: &mut TcpStream) -> String {
+        stream
+            .set_read_timeout(Some(Duration::from_secs(5)))
+            .expect("set HTTP fixture read timeout");
+        let mut bytes = Vec::new();
+        let mut buffer = [0_u8; 4096];
+        loop {
+            let read = stream.read(&mut buffer).expect("read HTTP fixture request");
+            assert!(read > 0, "HTTP fixture request closed before headers");
+            bytes.extend_from_slice(&buffer[..read]);
+            if bytes.windows(4).any(|value| value == b"\r\n\r\n") {
+                break;
+            }
+        }
+        String::from_utf8_lossy(&bytes).into_owned()
+    }
+
+    fn request_header(request: &str, expected_name: &str) -> Option<String> {
+        request.lines().find_map(|line| {
+            let (name, value) = line.split_once(':')?;
+            name.eq_ignore_ascii_case(expected_name)
+                .then(|| value.trim().to_string())
+        })
+    }
+
+    fn spawn_http_fixture(listener: TcpListener) -> std::thread::JoinHandle<String> {
+        std::thread::spawn(move || {
+            let (mut stream, _) = listener.accept().expect("accept HTTP fixture request");
+            let request = read_http_request(&mut stream);
+            stream
+                .write_all(
+                    b"HTTP/1.1 204 No Content\r\nContent-Length: 0\r\nConnection: close\r\n\r\n",
+                )
+                .expect("write HTTP fixture response");
+            request
+        })
+    }
+
+    #[tokio::test]
+    async fn factory_sets_the_agc_marker_as_a_default_header() {
+        let listener = TcpListener::bind("127.0.0.1:0").expect("bind HTTP fixture");
+        let address = listener.local_addr().expect("read HTTP fixture address");
+        let fixture = spawn_http_fixture(listener);
+        let client = agc_main_site_client_builder()
+            .build()
+            .expect("build AGC main-site client");
+        let response = client
+            .get(format!("http://{address}/api/auth/me"))
+            .send()
+            .await
+            .expect("send request");
+        let request = fixture.join().expect("join HTTP fixture");
+
+        assert_eq!(response.status(), reqwest::StatusCode::NO_CONTENT);
+        assert_eq!(
+            request_header(&request, AGC_CLIENT_MARKER_HEADER),
+            Some(AGC_CLIENT_MARKER_VALUE.to_string())
+        );
+        assert!(request_header(&request, AUTHORIZATION.as_str()).is_none());
+        assert!(request_header(&request, "idempotency-key").is_none());
+    }
+
+    #[tokio::test]
+    async fn factory_keeps_request_headers_and_transport_options_configurable() {
+        let listener = TcpListener::bind("127.0.0.1:0").expect("bind HTTP fixture");
+        let address = listener.local_addr().expect("read HTTP fixture address");
+        let fixture = spawn_http_fixture(listener);
+        let client = agc_main_site_client_builder()
+            .connect_timeout(Duration::from_secs(10))
+            .timeout(Duration::from_secs(60))
+            .redirect(reqwest::redirect::Policy::none())
+            .no_proxy()
+            .build()
+            .expect("build configured AGC main-site client");
+        let response = client
+            .post(format!("http://{address}/api/editor/images/generations"))
+            .bearer_auth("fixture-token")
+            .header("Idempotency-Key", "fixture-id")
+            .send()
+            .await
+            .expect("send configured request");
+        let request = fixture.join().expect("join HTTP fixture");
+
+        assert_eq!(response.status(), reqwest::StatusCode::NO_CONTENT);
+        assert_eq!(
+            request_header(&request, AGC_CLIENT_MARKER_HEADER),
+            Some(AGC_CLIENT_MARKER_VALUE.to_string())
+        );
+        assert_eq!(
+            request_header(&request, AUTHORIZATION.as_str()),
+            Some("Bearer fixture-token".to_string())
+        );
+        assert_eq!(
+            request_header(&request, "idempotency-key"),
+            Some("fixture-id".to_string())
+        );
+    }
+}
diff --git a/apps/ai-game-creator-shell/src-tauri/src/main.rs b/apps/ai-game-creator-shell/src-tauri/src/main.rs
index 245918c85..4a4897bec 100644
--- a/apps/ai-game-creator-shell/src-tauri/src/main.rs
+++ b/apps/ai-game-creator-shell/src-tauri/src/main.rs
@@ -245,6 +245,7 @@ mod debug;
 mod delegation;
 mod git_inspect;
 mod goal;
+mod http_client;
 mod image_inspect;
 mod isolated_agent;
 mod patchset;
diff --git a/local-docs/【实施方案】Issue226-AGC客户端主站请求统一标记-2026-09-01.md b/local-docs/【实施方案】Issue226-AGC客户端主站请求统一标记-2026-09-01.md
index cc2327c85..449122a9e 100644
--- a/local-docs/【实施方案】Issue226-AGC客户端主站请求统一标记-2026-09-01.md
+++ b/local-docs/【实施方案】Issue226-AGC客户端主站请求统一标记-2026-09-01.md
@@ -6,7 +6,7 @@
 - `#226 添加客户端特殊标识`：本方案实际实施范围
 - `#225 添加客户端埋点统计`：主站接收、落库和后台统计，本文只冻结交接契约，不在本次实施
 
-状态：阶段 1 已完成，待阶段 2 实施<br>
+状态：阶段 2 已完成，待阶段 3 实施<br>
 本方案不包含代码修改
 
 ## 1. 一句话交付结果
diff --git a/local-docs/【实施计划】Issue226-AGC客户端主站请求标记分阶段验收-2026-09-01.md b/local-docs/【实施计划】Issue226-AGC客户端主站请求标记分阶段验收-2026-09-01.md
index a8e0d9588..ad4ed2b44 100644
--- a/local-docs/【实施计划】Issue226-AGC客户端主站请求标记分阶段验收-2026-09-01.md
+++ b/local-docs/【实施计划】Issue226-AGC客户端主站请求标记分阶段验收-2026-09-01.md
@@ -6,7 +6,7 @@
 - `#226 添加客户端特殊标识`：本计划全部实施范围
 - `#225 添加客户端埋点统计`：只接收交接契约，不在本计划实现
 
-当前状态：阶段 1 已完成；阶段 2 尚未开始。阶段 0 的证据与验收记录见
+当前状态：阶段 2 已完成；阶段 3 尚未开始。阶段 0 的证据与验收记录见
 [【阶段验收】Issue226阶段0现状基线与契约冻结-2026-09-01.md](C:/projects/narrative/Genarrative/local-docs/【阶段验收】Issue226阶段0现状基线与契约冻结-2026-09-01.md)。
 
 ## 1. 交付目标
@@ -172,6 +172,15 @@ fn agc_main_site_client_builder() -> reqwest::ClientBuilder;
 - factory 的职责没有扩展到业务编排。
 - 现有测试或新增测试能锁定 Header 默认值。
 
+### 6.4 阶段 2 实施记录
+
+- 新增 `src-tauri/src/http_client.rs`，提供 `agc_main_site_client_builder()`。
+- factory 仅通过 `default_headers` 注入 `x-genarrative-client: agc`，不接管认证、幂等、请求体、重试或错误解析。
+- 调用方仍可在返回的 builder 上继续配置 connect timeout、request timeout、redirect policy 和 `no_proxy`。
+- 新增两个本地 TCP fixture 单元测试，验证真实发送请求带标记、请求级 Authorization/Idempotency-Key 保留，且 factory 不自动注入认证信息。
+- 阶段 2 验证命令：`cargo test --locked --manifest-path apps/ai-game-creator-shell/src-tauri/Cargo.toml http_client -- --nocapture`（2 tests passed）；`cargo fmt --manifest-path apps/ai-game-creator-shell/src-tauri/Cargo.toml -- --check` 通过。
+- 阶段 2 未迁移任何业务 Client 创建点；迁移属于阶段 3。
+
 ## 7. 阶段 3：主站 Client 创建点迁移
 
 ### 7.1 工作内容