fix(codex): strip Responses-Lite private header upstream

Root cause: Codex Desktop sends x-openai-internal-codex-responses-lite to its local backend as an internal client/backend capability signal. CCSwitchMulti rebuilds request headers and previously default-passed unknown headers to the real upstream, so official ChatGPT Codex and third-party OpenAI-compatible upstreams could receive the private Lite switch. After OpenAI tightened that path for gpt-5.5, the upstream rejects requests with HTTP 400: This model is not supported when using X-OpenAI-Internal-Codex-Responses-Lite.\n\nFix the boundary in the proxy forwarder instead of changing MultiRouter, catalog schema, or provider UI. The header policy now strips only the known Codex Responses-Lite private header before default passthrough. OAuth account/session/cache headers keep their existing behavior, preserving the login-stability work from the v3.16.3-23 line and avoiding broad header scrubbing.\n\nThe same fix was first prepared for upstream cc-switch on branch codex/strip-codex-responses-lite-header and submitted as farion1231#4727.\n\nTests added in forwarder cover official chatgpt.com Codex upstream stripping, third-party upstream stripping, and ordinary header preservation. memory.md records the root cause and future regression boundary.\n\nVerified:\n- cargo fmt --manifest-path src-tauri\\Cargo.toml --check\n- cargo test --manifest-path src-tauri\\Cargo.toml codex_responses_lite_header --lib\n- cargo test --manifest-path src-tauri\\Cargo.toml ordinary_headers_are_preserved_for_upstream --lib\n- git diff --check

Author: BigStrongSun

memory.md

@@ -1,5 +1,12 @@
 # CC Switch Repository Memory
 
+## 2026-06-28 Codex Responses-Lite Header Upstream Strip
+
+- `This model is not supported when using X-OpenAI-Internal-Codex-Responses-Lite` 的根因不是 MultiRouter 自身路由错误，而是 Codex Desktop 发给本地后端的内部协商头 `x-openai-internal-codex-responses-lite` 被 CC Switch / CCSwitchMulti 的 `forwarder.rs` 默认透传到了真实上游。OpenAI 在 2026-06-26 左右收紧 Lite 路径后，`gpt-5.5` 等模型会因此在 official ChatGPT Codex upstream 或第三方代理 upstream 返回 HTTP 400。
+- 正确修复边界在转发层 header policy：`src-tauri/src/proxy/forwarder.rs` 构建 `ordered_headers` 时，在默认透传前调用 `should_strip_codex_private_header_for_upstream()`，无条件移除 `x-openai-internal-codex-responses-lite`。不要把它修成 UI 开关、catalog schema、模型映射或 MultiRouter route 规则；也不要粗暴移除 OAuth/session/account headers，否则会破坏 Codex 官方登录态、前缀缓存和 CCSwitchMulti 之前的 OAuth login-preservation 修复。
+- 这次先在原版 `C:\Users\sunda\Documents\LLMservice\ccswitch official` 基于 `origin/main` 创建 `codex/strip-codex-responses-lite-header`，提交 `1e6a46b7 fix(proxy): strip Codex Responses-Lite header upstream`，并向 `farion1231/cc-switch` 提交 PR `#4727`，关联 issue `#4700`。随后把同一策略移植到 CCSwitchMulti `C:\Users\sunda\Documents\LLMservice\cc-switch` 的 `codex/merge-official-v3.16.4` 分支。
+- 回归测试落点：`proxy::forwarder::tests::codex_responses_lite_header_is_stripped_for_official_upstream`、`codex_responses_lite_header_is_stripped_for_third_party_upstream`、`ordinary_headers_are_preserved_for_upstream`。验证命令优先跑 `cargo fmt --manifest-path src-tauri\Cargo.toml --check`、`cargo test --manifest-path src-tauri\Cargo.toml codex_responses_lite_header --lib`、`cargo test --manifest-path src-tauri\Cargo.toml ordinary_headers_are_preserved_for_upstream --lib`、`git diff --check`。
+
 ## 2026-06-28 CCSwitchMulti v3.16.4-1 Prerelease
 
 - `v3.16.4-1` 已作为 BigStrongSun/ccswitchmulti 的 GitHub prerelease 发布：`https://github.com/BigStrongSun/ccswitchmulti/releases/tag/v3.16.4-1`。Release 为非 draft、`prerelease=true`，发布时间为 `2026-06-27T20:52:24Z`，target commit 为 `e0228d531d1a7086a808d706e6ecb2618de44f4c`（`docs(memory): record completed v3.16.4-1 merge`）。

src-tauri/src/proxy/forwarder.rs

@@ -1976,6 +1976,13 @@ impl RequestForwarder {
                 continue;
             }
 
+            // Codex Desktop 会给本地后端发送内部协商头。CCSwitchMulti 是上游反代，
+            // 不能把这些客户端私有信号继续透传，否则会让官方或第三方上游误入
+            // Responses-Lite 路径并拒绝部分模型。
+            if should_strip_codex_private_header_for_upstream(&url, key) {
+                continue;
+            }
+
             // --- 认证类 — 用 adapter 提供的认证头替换（在原始位置） ---
             if key_str.eq_ignore_ascii_case("authorization")
                 || key_str.eq_ignore_ascii_case("x-api-key")
@@ -3012,6 +3019,21 @@ fn is_managed_account_upstream_url(url: &str) -> bool {
         || (host == "chatgpt.com" && uri.path().starts_with("/backend-api/codex"))
 }
 
+/// 判断某个 Codex 客户端私有头是否应该在转发到上游前移除。
+///
+/// `x-openai-internal-codex-responses-lite` 是 Codex Desktop 与本地后端之间的内部
+/// 能力开关，不是公开 upstream API 契约。无论目标是官方 ChatGPT Codex 后端还是
+/// 第三方 OpenAI-compatible 服务，都不应由 CCSwitchMulti 继续转发。
+fn should_strip_codex_private_header_for_upstream(_url: &str, name: &http::HeaderName) -> bool {
+    is_codex_responses_lite_header(name)
+}
+
+/// 识别会触发上游 Responses-Lite 分支的 Codex 内部请求头。
+fn is_codex_responses_lite_header(name: &http::HeaderName) -> bool {
+    name.as_str()
+        .eq_ignore_ascii_case("x-openai-internal-codex-responses-lite")
+}
+
 fn headers_contain_proxy_placeholder(headers: &http::HeaderMap) -> bool {
     headers.values().any(|value| {
         value
@@ -3447,6 +3469,39 @@ mod tests {
         }
     }
 
+    // 验证官方 Codex upstream 不会收到 Codex Desktop 的 Responses-Lite 内部开关。
+    #[test]
+    fn codex_responses_lite_header_is_stripped_for_official_upstream() {
+        let header = http::HeaderName::from_static("x-openai-internal-codex-responses-lite");
+
+        assert!(should_strip_codex_private_header_for_upstream(
+            "https://chatgpt.com/backend-api/codex/responses",
+            &header
+        ));
+    }
+
+    // 验证第三方 OpenAI-compatible upstream 也不会收到官方客户端私有 header。
+    #[test]
+    fn codex_responses_lite_header_is_stripped_for_third_party_upstream() {
+        let header = http::HeaderName::from_static("x-openai-internal-codex-responses-lite");
+
+        assert!(should_strip_codex_private_header_for_upstream(
+            "https://api.example.com/v1/responses",
+            &header
+        ));
+    }
+
+    // 验证过滤策略只移除已知 Codex 私有头，不影响普通自定义 header 透传。
+    #[test]
+    fn ordinary_headers_are_preserved_for_upstream() {
+        let header = http::HeaderName::from_static("x-custom-feature");
+
+        assert!(!should_strip_codex_private_header_for_upstream(
+            "https://chatgpt.com/backend-api/codex/responses",
+            &header
+        ));
+    }
+
     #[test]
     fn single_provider_retryable_log_uses_single_provider_code() {
         let error = ProxyError::UpstreamError {