Route backend requests through the HTTP client factory (#34490)

## Why

Backend-backed features need to use the same outbound routing configuration as the rest of Codex.

## What changed

- Build the backend client on a route-aware client pool supplied by `HttpClientFactory`.
- Pass the configured factory through app-server account requests, cloud config loading, cloud tasks, and memory rate-limit checks.
- Preserve task query encoding, authentication headers, JSON request bodies, and ChatGPT cookie handling during the migration.

## Testing

- Add backend-client tests for proxy-policy propagation, task query encoding, bearer authentication, and JSON request bodies.

GitOrigin-RevId: c17d162e0dce9cec758df7cdeecf982207c6512b

codex-rs/app-server/src/request_processors/account_processor.rs

@@ -538,7 +538,7 @@ impl AccountRequestProcessor {
         let outgoing_clone = self.outgoing.clone();
         let config_manager = self.config_manager.clone();
         let thread_manager = Arc::clone(&self.thread_manager);
-        let chatgpt_base_url = self.config.chatgpt_base_url.clone();
+        let config = Arc::clone(&self.config);
         let active_login = self.active_login.clone();
         let auth_url = server.auth_url.clone();
         tokio::spawn(async move {
@@ -560,7 +560,7 @@ impl AccountRequestProcessor {
                 &outgoing_clone,
                 config_manager,
                 thread_manager,
-                chatgpt_base_url,
+                config,
                 login_id,
                 success,
                 error_msg,
@@ -617,7 +617,7 @@ impl AccountRequestProcessor {
         let outgoing_clone = self.outgoing.clone();
         let config_manager = self.config_manager.clone();
         let thread_manager = Arc::clone(&self.thread_manager);
-        let chatgpt_base_url = self.config.chatgpt_base_url.clone();
+        let config = Arc::clone(&self.config);
         let active_login = self.active_login.clone();
         tokio::spawn(async move {
             let (success, error_msg) = tokio::select! {
@@ -636,7 +636,7 @@ impl AccountRequestProcessor {
                 &outgoing_clone,
                 config_manager,
                 thread_manager,
-                chatgpt_base_url,
+                config,
                 login_id,
                 success,
                 error_msg,
@@ -751,6 +751,7 @@ impl AccountRequestProcessor {
         self.config_manager.replace_cloud_config_bundle_loader(
             self.auth_manager.clone(),
             self.config.chatgpt_base_url.clone(),
+            self.config.http_client_factory(),
         );
         self.config_manager
             .sync_default_client_residency_requirement()
@@ -789,7 +790,7 @@ impl AccountRequestProcessor {
         outgoing: &OutgoingMessageSender,
         config_manager: ConfigManager,
         thread_manager: Arc<ThreadManager>,
-        chatgpt_base_url: String,
+        config: Arc<Config>,
         login_id: Uuid,
         success: bool,
         error_msg: Option<String>,
@@ -806,8 +807,11 @@ impl AccountRequestProcessor {
         if success {
             let auth_manager = thread_manager.auth_manager();
             auth_manager.reload().await;
-            config_manager
-                .replace_cloud_config_bundle_loader(auth_manager.clone(), chatgpt_base_url);
+            config_manager.replace_cloud_config_bundle_loader(
+                auth_manager.clone(),
+                config.chatgpt_base_url.clone(),
+                config.http_client_factory(),
+            );
             config_manager
                 .sync_default_client_residency_requirement()
                 .await;
@@ -1028,8 +1032,11 @@ impl AccountRequestProcessor {
             ));
         }
 
-        let client = BackendClient::from_auth(self.config.chatgpt_base_url.clone(), &auth)
-            .map_err(|err| internal_error(format!("failed to construct backend client: {err}")))?;
+        let client = BackendClient::from_auth(
+            self.config.chatgpt_base_url.clone(),
+            &auth,
+            self.config.http_client_factory(),
+        );
 
         let (response, detailed_rate_limit_reset_credits) = tokio::join!(
             client.get_rate_limits_with_reset_credits(),
@@ -1098,8 +1105,11 @@ impl AccountRequestProcessor {
             ));
         }
 
-        let client = BackendClient::from_auth(self.config.chatgpt_base_url.clone(), &auth)
-            .map_err(|err| internal_error(format!("failed to construct backend client: {err}")))?;
+        let client = BackendClient::from_auth(
+            self.config.chatgpt_base_url.clone(),
+            &auth,
+            self.config.http_client_factory(),
+        );
         let profile = tokio::time::timeout(
             ACCOUNT_TOKEN_USAGE_FETCH_TIMEOUT,
             client.get_token_usage_profile(),
@@ -1125,8 +1135,11 @@ impl AccountRequestProcessor {
             ));
         }
 
-        let client = BackendClient::from_auth(self.config.chatgpt_base_url.clone(), &auth)
-            .map_err(|err| internal_error(format!("failed to construct backend client: {err}")))?;
+        let client = BackendClient::from_auth(
+            self.config.chatgpt_base_url.clone(),
+            &auth,
+            self.config.http_client_factory(),
+        );
         let messages = tokio::time::timeout(
             ACCOUNT_WORKSPACE_MESSAGES_FETCH_TIMEOUT,
             client.list_workspace_messages(),
@@ -1213,8 +1226,11 @@ impl AccountRequestProcessor {
             ));
         }
 
-        let client = BackendClient::from_auth(self.config.chatgpt_base_url.clone(), &auth)
-            .map_err(|err| internal_error(format!("failed to construct backend client: {err}")))?;
+        let client = BackendClient::from_auth(
+            self.config.chatgpt_base_url.clone(),
+            &auth,
+            self.config.http_client_factory(),
+        );
 
         match client
             .send_add_credits_nudge_email(Self::backend_credit_type(params.credit_type))