diff --git a/codex-rs/Cargo.lock b/codex-rs/Cargo.lock
index 6a6f7894c9..b3a1ea8803 100644
--- a/codex-rs/Cargo.lock
+++ b/codex-rs/Cargo.lock
@@ -2334,6 +2334,7 @@ dependencies = [
  "rustls-pki-types",
  "serde",
  "serde_json",
+ "sha2 0.10.9",
  "tempfile",
  "thiserror 2.0.18",
  "tokio",
diff --git a/codex-rs/cloud-config/src/lib.rs b/codex-rs/cloud-config/src/lib.rs
index 0beb91780c..d79bd8597a 100644
--- a/codex-rs/cloud-config/src/lib.rs
+++ b/codex-rs/cloud-config/src/lib.rs
@@ -20,6 +20,7 @@ use codex_config::CloudRequirementsLoadErrorCode;
 use codex_config::CloudRequirementsLoader;
 use codex_config::ConfigRequirementsToml;
 use codex_config::types::AuthCredentialsStoreMode;
+use codex_config::types::NetworkConfigToml;
 use codex_core::util::backoff;
 use codex_login::AuthManager;
 use codex_login::CodexAuth;
@@ -734,13 +735,47 @@ pub async fn cloud_requirements_loader_for_storage(
     credentials_store_mode: AuthCredentialsStoreMode,
     chatgpt_base_url: String,
 ) -> CloudRequirementsLoader {
-    let auth_manager = AuthManager::shared(
-        codex_home.clone(),
+    cloud_requirements_loader_for_storage_with_network_config(
+        codex_home,
         enable_codex_api_key_env,
         credentials_store_mode,
-        Some(chatgpt_base_url.clone()),
+        chatgpt_base_url,
+        /*network_config*/ None,
     )
-    .await;
+    .await
+}
+
+/// Loads cloud requirements while allowing resolved startup network config to reach auth recovery.
+pub async fn cloud_requirements_loader_for_storage_with_network_config(
+    codex_home: PathBuf,
+    enable_codex_api_key_env: bool,
+    credentials_store_mode: AuthCredentialsStoreMode,
+    chatgpt_base_url: String,
+    network_config: Option<&NetworkConfigToml>,
+) -> CloudRequirementsLoader {
+    let outbound_proxy_config =
+        codex_login::windows_system_proxy_config_from_network_config(network_config);
+    let auth_manager = if let Some(outbound_proxy_config) = outbound_proxy_config {
+        // Keep the existing startup auth path unless Windows system proxy discovery is selected.
+        Arc::new(
+            AuthManager::new_with_proxy_config(
+                codex_home.clone(),
+                enable_codex_api_key_env,
+                credentials_store_mode,
+                Some(chatgpt_base_url.clone()),
+                Some(outbound_proxy_config),
+            )
+            .await,
+        )
+    } else {
+        AuthManager::shared(
+            codex_home.clone(),
+            enable_codex_api_key_env,
+            credentials_store_mode,
+            Some(chatgpt_base_url.clone()),
+        )
+        .await
+    };
     cloud_requirements_loader(auth_manager, chatgpt_base_url, codex_home)
 }
 
diff --git a/codex-rs/cloud-tasks/src/util.rs b/codex-rs/cloud-tasks/src/util.rs
index 9a5056aa66..84b9fec4c8 100644
--- a/codex-rs/cloud-tasks/src/util.rs
+++ b/codex-rs/cloud-tasks/src/util.rs
@@ -44,15 +44,28 @@ pub fn normalize_base_url(input: &str) -> String {
 pub async fn load_auth_manager(chatgpt_base_url: Option<String>) -> Option<AuthManager> {
     // TODO: pass in cli overrides once cloud tasks properly support them.
     let config = Config::load_with_cli_overrides(Vec::new()).await.ok()?;
-    Some(
+    let outbound_proxy_config =
+        codex_login::windows_system_proxy_config_from_network_config(config.network.as_ref());
+    let chatgpt_base_url = chatgpt_base_url.or(Some(config.chatgpt_base_url));
+    Some(if let Some(outbound_proxy_config) = outbound_proxy_config {
+        // Keep the existing cloud auth path unless Windows system proxy discovery is selected.
+        AuthManager::new_with_proxy_config(
+            config.codex_home.to_path_buf(),
+            /*enable_codex_api_key_env*/ false,
+            config.cli_auth_credentials_store_mode,
+            chatgpt_base_url,
+            Some(outbound_proxy_config),
+        )
+        .await
+    } else {
         AuthManager::new(
             config.codex_home.to_path_buf(),
             /*enable_codex_api_key_env*/ false,
             config.cli_auth_credentials_store_mode,
-            chatgpt_base_url.or(Some(config.chatgpt_base_url)),
+            chatgpt_base_url,
         )
-        .await,
-    )
+        .await
+    })
 }
 
 /// Build headers for ChatGPT-backed requests: `User-Agent`, optional `Authorization`,
diff --git a/codex-rs/codex-client/Cargo.toml b/codex-rs/codex-client/Cargo.toml
index cca70228db..9e477ba5b4 100644
--- a/codex-rs/codex-client/Cargo.toml
+++ b/codex-rs/codex-client/Cargo.toml
@@ -26,6 +26,7 @@ codex-utils-rustls-provider = { workspace = true }
 zstd = { workspace = true }
 
 [target.'cfg(target_os = "windows")'.dependencies]
+sha2 = { workspace = true }
 windows-sys = { version = "0.52", features = [
     "Win32_Foundation",
     "Win32_Networking_WinHttp",
diff --git a/codex-rs/exec/src/lib.rs b/codex-rs/exec/src/lib.rs
index f6088df77b..90e61fa333 100644
--- a/codex-rs/exec/src/lib.rs
+++ b/codex-rs/exec/src/lib.rs
@@ -51,7 +51,7 @@ use codex_app_server_protocol::TurnStartParams;
 use codex_app_server_protocol::TurnStartResponse;
 use codex_app_server_protocol::TurnStartedNotification;
 use codex_arg0::Arg0DispatchPaths;
-use codex_cloud_config::cloud_requirements_loader_for_storage;
+use codex_cloud_config::cloud_requirements_loader_for_storage_with_network_config;
 use codex_config::ConfigLoadError;
 use codex_config::ConfigLoadOptions;
 use codex_config::LoaderOverrides;
@@ -364,11 +364,12 @@ pub async fn run_main(cli: Cli, arg0_paths: Arg0DispatchPaths) -> anyhow::Result
         .clone()
         .unwrap_or_else(|| "https://chatgpt.com/backend-api/".to_string());
     // TODO(gt): Make cloud requirements failures blocking once we can fail-closed.
-    let cloud_requirements = cloud_requirements_loader_for_storage(
+    let cloud_requirements = cloud_requirements_loader_for_storage_with_network_config(
         codex_home.to_path_buf(),
         /*enable_codex_api_key_env*/ false,
         config_toml.cli_auth_credentials_store.unwrap_or_default(),
         chatgpt_base_url,
+        config_toml.network.as_ref(),
     )
     .await;
     let run_cli_overrides = cli_kv_overrides.clone();
diff --git a/codex-rs/login/src/lib.rs b/codex-rs/login/src/lib.rs
index 3008ddc665..44824c025b 100644
--- a/codex-rs/login/src/lib.rs
+++ b/codex-rs/login/src/lib.rs
@@ -50,4 +50,5 @@ pub use auth::read_openai_api_key_from_env;
 pub use auth::save_auth;
 pub use auth_env_telemetry::AuthEnvTelemetry;
 pub use auth_env_telemetry::collect_auth_env_telemetry;
+pub use outbound_proxy::windows_system_proxy_config_from_network_config;
 pub use token_data::TokenData;
diff --git a/codex-rs/login/src/outbound_proxy.rs b/codex-rs/login/src/outbound_proxy.rs
index 89281aead5..b641930b37 100644
--- a/codex-rs/login/src/outbound_proxy.rs
+++ b/codex-rs/login/src/outbound_proxy.rs
@@ -21,6 +21,22 @@ pub(crate) fn outbound_proxy_config_from_network_config(
     }
 }
 
+/// Returns the auth proxy config for the explicit Windows system-proxy startup path.
+pub fn windows_system_proxy_config_from_network_config(
+    network: Option<&NetworkConfigToml>,
+) -> Option<OutboundProxyConfig> {
+    let network = network?;
+    if !system_proxy_mode_enabled()
+        || network.proxy_mode != Some(NetworkProxyMode::System)
+        || network.proxy_url.is_some()
+    {
+        return None;
+    }
+
+    // Legacy startup auth builders only need the explicit Windows system-proxy selection here.
+    Some(outbound_proxy_config_from_network_config(network))
+}
+
 const fn system_proxy_mode_enabled() -> bool {
     cfg!(target_os = "windows")
 }
@@ -55,4 +71,36 @@ mod tests {
         };
         assert_eq!(config.mode, expected);
     }
+
+    #[test]
+    fn startup_system_proxy_config_is_scoped_to_windows_pac_path() {
+        let network = NetworkConfigToml {
+            proxy_mode: Some(NetworkProxyMode::System),
+            proxy_url: None,
+        };
+
+        let config = windows_system_proxy_config_from_network_config(Some(&network));
+
+        if cfg!(target_os = "windows") {
+            assert_eq!(
+                config,
+                Some(outbound_proxy_config_from_network_config(&network))
+            );
+        } else {
+            assert_eq!(config, None);
+        }
+    }
+
+    #[test]
+    fn startup_system_proxy_config_skips_concrete_proxy_override() {
+        let network = NetworkConfigToml {
+            proxy_mode: Some(NetworkProxyMode::System),
+            proxy_url: Some("http://proxy.example.test:8080".to_string()),
+        };
+
+        assert_eq!(
+            windows_system_proxy_config_from_network_config(Some(&network)),
+            None
+        );
+    }
 }
diff --git a/codex-rs/tui/src/lib.rs b/codex-rs/tui/src/lib.rs
index 9a5e2d5a38..f3723cace6 100644
--- a/codex-rs/tui/src/lib.rs
+++ b/codex-rs/tui/src/lib.rs
@@ -38,7 +38,7 @@ use codex_app_server_protocol::ThreadListCwdFilter;
 use codex_app_server_protocol::ThreadListParams;
 use codex_app_server_protocol::ThreadSortKey as AppServerThreadSortKey;
 use codex_app_server_protocol::ThreadSourceKind;
-use codex_cloud_config::cloud_requirements_loader_for_storage;
+use codex_cloud_config::cloud_requirements_loader_for_storage_with_network_config;
 use codex_config::CloudRequirementsLoader;
 use codex_config::ConfigLoadError;
 use codex_config::LoaderOverrides;
@@ -1011,11 +1011,12 @@ pub async fn run_main(
         .chatgpt_base_url
         .clone()
         .unwrap_or_else(|| "https://chatgpt.com/backend-api/".to_string());
-    let cloud_requirements = cloud_requirements_loader_for_storage(
+    let cloud_requirements = cloud_requirements_loader_for_storage_with_network_config(
         codex_home.to_path_buf(),
         /*enable_codex_api_key_env*/ false,
         config_toml.cli_auth_credentials_store.unwrap_or_default(),
         chatgpt_base_url,
+        config_toml.network.as_ref(),
     )
     .await;
 
@@ -1455,11 +1456,12 @@ async fn run_ratatui_app(
         // rebuild config. This avoids missing newly available cloud requirements due to login
         // status detection edge cases.
         if show_login_screen && !uses_remote_workspace {
-            cloud_requirements = cloud_requirements_loader_for_storage(
+            cloud_requirements = cloud_requirements_loader_for_storage_with_network_config(
                 initial_config.codex_home.to_path_buf(),
                 /*enable_codex_api_key_env*/ false,
                 initial_config.cli_auth_credentials_store_mode,
                 initial_config.chatgpt_base_url.clone(),
+                initial_config.network.as_ref(),
             )
             .await;
         }