diff --git a/codex-rs/network-proxy/src/mitm.rs b/codex-rs/network-proxy/src/mitm.rs
index 9056e48f50..af2e0ac066 100644
--- a/codex-rs/network-proxy/src/mitm.rs
+++ b/codex-rs/network-proxy/src/mitm.rs
@@ -33,6 +33,7 @@ use rama_http::Response;
 use rama_http::StatusCode;
 use rama_http::Uri;
 use rama_http::header::HOST;
+use rama_http::header::HeaderName;
 use rama_http::layer::remove_header::RemoveRequestHeaderLayer;
 use rama_http::layer::remove_header::RemoveResponseHeaderLayer;
 use rama_http_backend::server::HttpServer;
@@ -85,6 +86,10 @@ enum MitmPolicyDecision {
 
 const MITM_INSPECT_BODIES: bool = false;
 const MITM_MAX_BODY_BYTES: usize = 4096;
+const CREDENTIAL_ROUTE_CONNECTOR_ID_HEADER: &str =
+    "x-openai-internal-credential-route-connector-id";
+const CREDENTIAL_ROUTE_LINK_ID_HEADER: &str = "x-openai-internal-credential-route-link-id";
+const CREDENTIAL_ROUTE_REQUEST_URL_HEADER: &str = "x-openai-internal-credential-route-request-url";
 
 impl std::fmt::Debug for MitmState {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
@@ -234,7 +239,12 @@ async fn forward_request(req: Request, request_ctx: &MitmRequestContext) -> Resu
         && let Some(credentialed_route_proxy) = actions.credentialed_route_proxy.as_ref()
     {
         let (proxy_uri, proxy_authority) =
-            credentialed_route_proxy_request(credentialed_route_proxy, &original_request_uri)?;
+            credentialed_route_proxy_request(credentialed_route_proxy)?;
+        apply_credentialed_route_proxy_headers(
+            &mut parts.headers,
+            credentialed_route_proxy,
+            &original_request_uri,
+        )?;
         parts.uri = proxy_uri;
         parts
             .headers
@@ -562,19 +572,33 @@ fn build_https_uri(authority: &str, path: &str) -> Result<Uri> {
 
 fn credentialed_route_proxy_request(
     action: &crate::mitm_hook::CredentialedRouteProxyAction,
-    request_uri: &Uri,
 ) -> Result<(Uri, String)> {
-    let mut proxy_url = Url::parse(&action.proxy_url)
+    let proxy_url = Url::parse(&action.proxy_url)
         .with_context(|| format!("invalid credentialed route proxy URL {}", action.proxy_url))?;
-    proxy_url
-        .query_pairs_mut()
-        .append_pair("link_id", &action.link_id)
-        .append_pair("connector_id", &action.connector_id)
-        .append_pair("request_url", &request_uri.to_string());
     let proxy_authority = url_authority_header_value(&proxy_url)?;
     Ok((proxy_url.as_str().parse()?, proxy_authority))
 }
 
+fn apply_credentialed_route_proxy_headers(
+    headers: &mut HeaderMap,
+    action: &crate::mitm_hook::CredentialedRouteProxyAction,
+    request_uri: &Uri,
+) -> Result<()> {
+    headers.insert(
+        HeaderName::from_static(CREDENTIAL_ROUTE_CONNECTOR_ID_HEADER),
+        HeaderValue::from_str(&action.connector_id)?,
+    );
+    headers.insert(
+        HeaderName::from_static(CREDENTIAL_ROUTE_LINK_ID_HEADER),
+        HeaderValue::from_str(&action.link_id)?,
+    );
+    headers.insert(
+        HeaderName::from_static(CREDENTIAL_ROUTE_REQUEST_URL_HEADER),
+        HeaderValue::from_str(&request_uri.to_string())?,
+    );
+    Ok(())
+}
+
 fn url_authority_header_value(url: &Url) -> Result<String> {
     let host = url
         .host_str()
diff --git a/codex-rs/network-proxy/src/mitm_tests.rs b/codex-rs/network-proxy/src/mitm_tests.rs
index b069cafbb5..e0e9d0bb2d 100644
--- a/codex-rs/network-proxy/src/mitm_tests.rs
+++ b/codex-rs/network-proxy/src/mitm_tests.rs
@@ -285,13 +285,32 @@ fn credentialed_route_proxy_request_rewrites_upstream_target() {
         proxy_url: "http://localhost:8080/api/codex/credential_routes/proxy".to_string(),
     };
     let request_uri: Uri = "https://api.example.com/v1/items?limit=5".parse().unwrap();
+    let mut headers = HeaderMap::new();
+    headers.insert(
+        HeaderName::from_static(CREDENTIAL_ROUTE_REQUEST_URL_HEADER),
+        HeaderValue::from_static("https://spoofed.example.com"),
+    );
 
-    let (proxy_uri, proxy_authority) =
-        credentialed_route_proxy_request(&action, &request_uri).unwrap();
+    let (proxy_uri, proxy_authority) = credentialed_route_proxy_request(&action).unwrap();
+    apply_credentialed_route_proxy_headers(&mut headers, &action, &request_uri).unwrap();
 
     assert_eq!(
         proxy_uri.to_string(),
-        "http://localhost:8080/api/codex/credential_routes/proxy?link_id=link_123&connector_id=connector_123&request_url=https%3A%2F%2Fapi.example.com%2Fv1%2Fitems%3Flimit%3D5"
+        "http://localhost:8080/api/codex/credential_routes/proxy"
     );
     assert_eq!(proxy_authority, "localhost:8080");
+    assert_eq!(
+        headers.get(CREDENTIAL_ROUTE_CONNECTOR_ID_HEADER),
+        Some(&HeaderValue::from_static("connector_123"))
+    );
+    assert_eq!(
+        headers.get(CREDENTIAL_ROUTE_LINK_ID_HEADER),
+        Some(&HeaderValue::from_static("link_123"))
+    );
+    assert_eq!(
+        headers.get(CREDENTIAL_ROUTE_REQUEST_URL_HEADER),
+        Some(&HeaderValue::from_static(
+            "https://api.example.com/v1/items?limit=5"
+        ))
+    );
 }