Remove the 1 MiB response limit for explicit model catalogs (#56525)

## What changed

Fetch catalogs configured with `model_catalog_url` without a response-body size limit, allowing responses larger than 1 MiB. Remove the oversized-response rejection test and update the catalog client documentation to drop the limit requirement.

GitOrigin-RevId: acd0dbbac5d548596b50faa309496de2db3588df

codex-rs/codex-api/src/endpoint/models.rs

@@ -92,8 +92,8 @@ impl<T: HttpTransport> ModelsClient<T> {
 
     /// Fetches a catalog using the provider's auth and retry policy without decoding it.
     ///
-    /// Callers accepting provider-controlled catalogs must set a response-body limit
-    /// and validate the native response without including raw values in diagnostics.
+    /// Callers accepting provider-controlled catalogs must validate the native response
+    /// without including raw values in diagnostics.
     pub async fn list_models_raw(
         &self,
         request_url: String,

codex-rs/model-provider/src/models_endpoint.rs

@@ -44,8 +44,6 @@ use crate::combined_auth::compose_auth;
 
 const MODELS_REFRESH_TIMEOUT: Duration = Duration::from_secs(5);
 const MODELS_ENDPOINT: &str = "/models";
-// Bound downloads from explicitly configured catalogs before decoding or caching them.
-const MAX_MODEL_CATALOG_BYTES: usize = 1024 * 1024;
 
 /// Provider-owned OpenAI-compatible `/models` endpoint.
 #[derive(Debug)]
@@ -157,13 +155,12 @@ impl OpenAiModelsEndpoint {
                 .await?;
             let client = ModelsClient::new(transport, api_provider, api_auth)
                 .with_telemetry(Some(request_telemetry));
-            let response_body_limit_bytes = self
-                .provider_info
-                .model_catalog_url
-                .as_ref()
-                .map(|_| MAX_MODEL_CATALOG_BYTES);
             client
-                .list_models(request_url, HeaderMap::new(), response_body_limit_bytes)
+                .list_models(
+                    request_url,
+                    HeaderMap::new(),
+                    /*response_body_limit_bytes*/ None,
+                )
                 .await
                 .map_err(|mut error| {
                     if self.provider_info.model_catalog_url.is_some()
@@ -437,7 +434,6 @@ mod tests {
     use codex_models_manager::model_info::model_info_from_slug;
     use codex_protocol::auth::AuthMode;
     use codex_protocol::config_types::ModelProviderAuthInfo;
-    use codex_protocol::error::CodexErrorDetails;
     use codex_protocol::openai_models::ModelVisibility;
     use codex_protocol::openai_models::ModelsResponse;
     use pretty_assertions::assert_eq;
@@ -932,41 +928,6 @@ mod tests {
         }
     }
 
-    #[tokio::test]
-    async fn explicit_catalog_rejects_oversized_response() {
-        let server = MockServer::start().await;
-        let mut body = br#"{"models":[]}"#.to_vec();
-        body.resize(MAX_MODEL_CATALOG_BYTES + 1, b' ');
-        Mock::given(method("GET"))
-            .and(path("/codex/models"))
-            .respond_with(ResponseTemplate::new(/*s*/ 200).set_body_bytes(body))
-            .expect(1)
-            .mount(&server)
-            .await;
-        let endpoint = OpenAiModelsEndpoint::new(
-            ModelProviderInfo {
-                model_catalog_url: Some(format!("{}/codex/models", server.uri()).into()),
-                ..ModelProviderInfo::default()
-            },
-            /*auth_manager*/ None,
-            /*gateway_auth_manager*/ None,
-        );
-        let error = endpoint
-            .list_models(
-                "1.2.3",
-                HttpClientFactory::new(OutboundProxyPolicy::ReqwestDefault),
-            )
-            .await
-            .expect_err("oversized catalog should be rejected");
-        let CodexErrorDetails::InvalidRequest(message) = error.details() else {
-            panic!("expected a response-size error, got {error:?}");
-        };
-        assert_eq!(
-            message,
-            &format!("response body exceeds the {MAX_MODEL_CATALOG_BYTES} byte limit")
-        );
-    }
-
     #[tokio::test]
     async fn explicit_catalog_rejects_redirects_without_forwarding_provider_credentials() {
         let server = MockServer::start().await;