diff --git a/src-tauri/src/proxy/forwarder.rs b/src-tauri/src/proxy/forwarder.rs
index c60470dbb..d803277ef 100644
--- a/src-tauri/src/proxy/forwarder.rs
+++ b/src-tauri/src/proxy/forwarder.rs
@@ -65,6 +65,8 @@ pub struct RequestForwarder {
     copilot_optimizer_config: CopilotOptimizerConfig,
     /// 非流式请求超时（秒）
     non_streaming_timeout: std::time::Duration,
+    /// 流式请求响应头等待超时（秒）
+    streaming_first_byte_timeout: std::time::Duration,
 }
 
 impl RequestForwarder {
@@ -80,7 +82,7 @@ impl RequestForwarder {
         current_provider_id_at_start: String,
         session_id: String,
         session_client_provided: bool,
-        _streaming_first_byte_timeout: u64,
+        streaming_first_byte_timeout: u64,
         _streaming_idle_timeout: u64,
         rectifier_config: RectifierConfig,
         optimizer_config: OptimizerConfig,
@@ -100,6 +102,9 @@ impl RequestForwarder {
             optimizer_config,
             copilot_optimizer_config,
             non_streaming_timeout: std::time::Duration::from_secs(non_streaming_timeout),
+            streaming_first_byte_timeout: std::time::Duration::from_secs(
+                streaming_first_byte_timeout,
+            ),
         }
     }
 
@@ -1412,35 +1417,60 @@ impl RequestForwarder {
             .map(|u| u.starts_with("socks5"))
             .unwrap_or(false);
 
-        let uri: http::Uri = url
-            .parse()
-            .map_err(|e| ProxyError::ForwardFailed(format!("Invalid URL '{url}': {e}")))?;
+        let preserve_exact_header_case = should_preserve_exact_header_case(
+            adapter.name(),
+            provider,
+            resolved_claude_api_format.as_deref(),
+            is_copilot,
+        );
 
         // 发送请求
-        let response = if is_socks_proxy {
-            // SOCKS5 代理：只能走 reqwest（不支持 header case 保留）
-            log::debug!("[Forwarder] Using reqwest for SOCKS5 proxy");
+        let response = if is_socks_proxy || !preserve_exact_header_case {
+            // OpenAI / Copilot / Codex 类后端不依赖原始 header 大小写；走 reqwest
+            // 连接池，避免 raw TCP/TLS path 每次请求都重新握手。SOCKS5 也只能走 reqwest。
+            log::debug!(
+                "[Forwarder] Using pooled reqwest client (preserve_exact_header_case={preserve_exact_header_case}, socks_proxy={is_socks_proxy})"
+            );
             let client = super::http_client::get();
             let mut request = client.post(&url);
-            if !self.non_streaming_timeout.is_zero() {
+            let request_is_streaming =
+                is_streaming_request(&effective_endpoint, &filtered_body, headers);
+            if request_is_streaming {
+                // reqwest 的 timeout 是整请求超时；流式请求交给 response_processor
+                // 的首包/静默期超时控制，避免长流被总时长误杀。
+                request = request.timeout(std::time::Duration::from_secs(24 * 60 * 60));
+            } else if !self.non_streaming_timeout.is_zero() {
                 request = request.timeout(self.non_streaming_timeout);
             }
             for (key, value) in &ordered_headers {
                 request = request.header(key, value);
             }
-            let reqwest_resp = request.body(body_bytes).send().await.map_err(|e| {
-                if e.is_timeout() {
-                    ProxyError::Timeout(format!("请求超时: {e}"))
-                } else if e.is_connect() {
-                    ProxyError::ForwardFailed(format!("连接失败: {e}"))
+            let send = request.body(body_bytes).send();
+            let send_result = if request_is_streaming {
+                let header_timeout = if self.streaming_first_byte_timeout.is_zero() {
+                    timeout
                 } else {
-                    ProxyError::ForwardFailed(e.to_string())
-                }
-            })?;
+                    self.streaming_first_byte_timeout
+                };
+                tokio::time::timeout(header_timeout, send)
+                    .await
+                    .map_err(|_| {
+                        ProxyError::Timeout(format!(
+                            "流式响应首包超时: {}s（上游未返回响应头）",
+                            header_timeout.as_secs()
+                        ))
+                    })?
+            } else {
+                send.await
+            };
+            let reqwest_resp = send_result.map_err(map_reqwest_send_error)?;
             ProxyResponse::Reqwest(reqwest_resp)
         } else {
             // HTTP 代理或直连：走 hyper raw write（保持 header 大小写）
             // 如果有 HTTP 代理，hyper_client 会用 CONNECT 隧道穿过代理
+            let uri: http::Uri = url
+                .parse()
+                .map_err(|e| ProxyError::ForwardFailed(format!("Invalid URL '{url}': {e}")))?;
             super::hyper_client::send_request(
                 uri,
                 http::Method::POST,
@@ -1865,11 +1895,24 @@ fn build_codex_oauth_session_headers(
     headers
 }
 
-fn should_force_identity_encoding(
-    endpoint: &str,
-    body: &Value,
-    headers: &axum::http::HeaderMap,
+fn should_preserve_exact_header_case(
+    adapter_name: &str,
+    provider: &Provider,
+    resolved_claude_api_format: Option<&str>,
+    is_copilot: bool,
 ) -> bool {
+    if matches!(adapter_name, "Codex" | "Gemini") {
+        return false;
+    }
+
+    if is_copilot || provider.is_codex_oauth() {
+        return false;
+    }
+
+    matches!(resolved_claude_api_format, None | Some("anthropic"))
+}
+
+fn is_streaming_request(endpoint: &str, body: &Value, headers: &axum::http::HeaderMap) -> bool {
     if body
         .get("stream")
         .and_then(|value| value.as_bool())
@@ -1889,6 +1932,24 @@ fn should_force_identity_encoding(
         .unwrap_or(false)
 }
 
+fn should_force_identity_encoding(
+    endpoint: &str,
+    body: &Value,
+    headers: &axum::http::HeaderMap,
+) -> bool {
+    is_streaming_request(endpoint, body, headers)
+}
+
+fn map_reqwest_send_error(error: reqwest::Error) -> ProxyError {
+    if error.is_timeout() {
+        ProxyError::Timeout(format!("请求超时: {error}"))
+    } else if error.is_connect() {
+        ProxyError::ForwardFailed(format!("连接失败: {error}"))
+    } else {
+        ProxyError::ForwardFailed(error.to_string())
+    }
+}
+
 fn summarize_text_for_log(text: &str, max_chars: usize) -> String {
     let normalized = text.split_whitespace().collect::<Vec<_>>().join(" ");
     let trimmed = normalized.trim();
@@ -1909,6 +1970,26 @@ mod tests {
     use axum::http::HeaderMap;
     use serde_json::json;
 
+    fn test_provider_with_type(provider_type: Option<&str>) -> Provider {
+        Provider {
+            id: "provider-1".to_string(),
+            name: "Provider 1".to_string(),
+            settings_config: json!({}),
+            website_url: None,
+            category: None,
+            created_at: None,
+            sort_index: None,
+            notes: None,
+            meta: provider_type.map(|value| crate::provider::ProviderMeta {
+                provider_type: Some(value.to_string()),
+                ..Default::default()
+            }),
+            icon: None,
+            icon_color: None,
+            in_failover_queue: false,
+        }
+    }
+
     #[test]
     fn single_provider_retryable_log_uses_single_provider_code() {
         let error = ProxyError::UpstreamError {
@@ -1996,6 +2077,49 @@ mod tests {
         );
     }
 
+    #[test]
+    fn exact_header_case_preserved_for_native_claude_only() {
+        let provider = test_provider_with_type(None);
+
+        assert!(should_preserve_exact_header_case(
+            "Claude",
+            &provider,
+            Some("anthropic"),
+            false
+        ));
+        assert!(!should_preserve_exact_header_case(
+            "Claude",
+            &provider,
+            Some("openai_responses"),
+            false
+        ));
+        assert!(!should_preserve_exact_header_case(
+            "Codex", &provider, None, false
+        ));
+        assert!(!should_preserve_exact_header_case(
+            "Gemini", &provider, None, false
+        ));
+    }
+
+    #[test]
+    fn exact_header_case_skipped_for_codex_oauth_and_copilot() {
+        let codex_oauth = test_provider_with_type(Some("codex_oauth"));
+        let copilot = test_provider_with_type(Some("github_copilot"));
+
+        assert!(!should_preserve_exact_header_case(
+            "Claude",
+            &codex_oauth,
+            Some("openai_responses"),
+            false
+        ));
+        assert!(!should_preserve_exact_header_case(
+            "Claude",
+            &copilot,
+            Some("openai_chat"),
+            true
+        ));
+    }
+
     #[test]
     fn rewrite_claude_transform_endpoint_strips_beta_for_chat_completions() {
         let (endpoint, passthrough_query) = rewrite_claude_transform_endpoint(
@@ -2161,6 +2285,17 @@ mod tests {
         ));
     }
 
+    #[test]
+    fn streaming_request_detects_gemini_sse_without_body_stream_flag() {
+        let headers = HeaderMap::new();
+
+        assert!(is_streaming_request(
+            "/v1beta/models/gemini-2.5-pro:streamGenerateContent?alt=sse",
+            &json!({ "model": "gemini-2.5-pro" }),
+            &headers
+        ));
+    }
+
     #[test]
     fn force_identity_for_sse_accept_header() {
         let mut headers = HeaderMap::new();