feat: add openai to codex translation

Co-authored-by: Codex <noreply@openai.com>

docs/implementation-status.md

@@ -14,7 +14,7 @@ Update this file before each feature commit.
 | TLS headers and fingerprint | Completed | pending codex headers commit | `cargo test codex_headers_include_desktop_identity_and_turn_state`; `cargo tree \| rg 'reqwest\|rustls'`; full `fmt/test/clippy` before commit | Adds Codex Desktop fingerprint model, exact identity/request headers, and pinned reqwest/rustls client builder. |
 | Cookie persistence | Completed | pending cookies commit | `cargo test cookie_jar_captures_and_replays_account_scoped_cookies`; full `fmt/test/clippy` before commit | Adds account-scoped in-memory Cookie jar and repository shell; database persistence follows storage integration. |
 | Account pool and refresh | Completed | pending accounts commit | `cargo test account_pool_skips_expired_disabled_banned_and_quota_exhausted_accounts`; full `fmt/test/clippy` before commit | Adds account statuses, acquisition filter, lifecycle events, token pair, OAuth config, and refresh policy shell. |
-| Translation | Planned |  |  |  |
+| Translation | Completed | pending translation commit | `cargo test chat_completion_translates_to_codex_response_request`; full `fmt/test/clippy` before commit | Adds OpenAI Chat request types, Codex Responses request type, translation, and OpenAI-compatible error body helper. |
 | HTTP routes | Planned |  |  |  |
 | Upstream lifecycle | Planned |  |  |  |
 | Fingerprint updates | Planned |  |  |  |

docs/superpowers/plans/2026-06-11-codex-proxy-rs.md

@@ -2310,7 +2310,7 @@ git commit -m "feat: add account pool foundation"
 - Modify: `/home/zyy/桌面/Codes/codex-proxy-rs/src/lib.rs`
 - Test: `/home/zyy/桌面/Codes/codex-proxy-rs/tests/routes_chat_test.rs`
 
-- [ ] **Step 1: Write failing translation test**
+- [x] **Step 1: Write failing translation test**
 
 Create `/home/zyy/桌面/Codes/codex-proxy-rs/tests/routes_chat_test.rs`:
 
@@ -2335,7 +2335,7 @@ fn chat_completion_translates_to_codex_response_request() {
 }
 ```
 
-- [ ] **Step 2: Run test and verify RED**
+- [x] **Step 2: Run test and verify RED**
 
 Run:
 
@@ -2345,7 +2345,7 @@ cargo test chat_completion_translates_to_codex_response_request
 
 Expected: compile failure because translation module does not exist.
 
-- [ ] **Step 3: Implement minimal translation types**
+- [x] **Step 3: Implement minimal translation types**
 
 Modify `/home/zyy/桌面/Codes/codex-proxy-rs/src/lib.rs`:
 
@@ -2463,7 +2463,7 @@ pub enum ResponseFormat {
 }
 ```
 
-- [ ] **Step 4: Verify translation**
+- [x] **Step 4: Verify translation**
 
 Run:
 
@@ -2473,7 +2473,7 @@ cargo test chat_completion_translates_to_codex_response_request
 
 Expected: pass.
 
-- [ ] **Step 5: Commit translation layer**
+- [x] **Step 5: Commit translation layer**
 
 ```bash
 git add src/translation src/codex/types.rs src/lib.rs tests/routes_chat_test.rs

src/codex/types.rs

@@ -1 +1,15 @@
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
 
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct CodexResponsesRequest {
+    pub model: String,
+    pub instructions: String,
+    pub input: Vec<Value>,
+    pub stream: bool,
+    pub store: bool,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub reasoning: Option<Value>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub tools: Option<Vec<Value>>,
+}

src/lib.rs

@@ -10,3 +10,4 @@ pub mod logs;
 pub mod pagination;
 pub mod state;
 pub mod storage;
+pub mod translation;

src/translation/codex_to_openai.rs

@@ -0,0 +1,12 @@
+use serde_json::{json, Value};
+
+pub fn openai_error(message: &str, code: &str) -> Value {
+    json!({
+        "error": {
+            "message": message,
+            "type": "server_error",
+            "param": null,
+            "code": code
+        }
+    })
+}

src/translation/mod.rs

@@ -0,0 +1,3 @@
+pub mod codex_to_openai;
+pub mod openai_to_codex;
+pub mod schema;

src/translation/openai_to_codex.rs

@@ -0,0 +1,43 @@
+use serde::{Deserialize, Serialize};
+use serde_json::json;
+
+use crate::{
+    codex::types::CodexResponsesRequest,
+    error::{AppError, AppResult},
+};
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ChatCompletionRequest {
+    pub model: String,
+    #[serde(default)]
+    pub stream: bool,
+    pub messages: Vec<ChatMessage>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct ChatMessage {
+    pub role: String,
+    pub content: String,
+}
+
+pub fn translate_chat_to_codex(req: ChatCompletionRequest) -> AppResult<CodexResponsesRequest> {
+    if req.messages.is_empty() {
+        return Err(AppError::BadRequest(
+            "messages must not be empty".to_string(),
+        ));
+    }
+    let input = req
+        .messages
+        .into_iter()
+        .map(|message| json!({ "role": message.role, "content": message.content }))
+        .collect();
+    Ok(CodexResponsesRequest {
+        model: req.model,
+        instructions: String::new(),
+        input,
+        stream: req.stream,
+        store: false,
+        reasoning: None,
+        tools: None,
+    })
+}

src/translation/schema.rs

@@ -0,0 +1,6 @@
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ResponseFormat {
+    Text,
+    JsonObject,
+    JsonSchema,
+}

tests/routes_chat_test.rs

@@ -0,0 +1,20 @@
+use codex_proxy_rs::translation::openai_to_codex::{
+    translate_chat_to_codex, ChatCompletionRequest, ChatMessage,
+};
+
+#[test]
+fn chat_completion_translates_to_codex_response_request() {
+    let req = ChatCompletionRequest {
+        model: "gpt-5.4".to_string(),
+        stream: true,
+        messages: vec![ChatMessage {
+            role: "user".to_string(),
+            content: "hello".to_string(),
+        }],
+    };
+
+    let codex = translate_chat_to_codex(req).unwrap();
+    assert_eq!(codex.model, "gpt-5.4");
+    assert!(codex.stream);
+    assert_eq!(codex.input[0]["role"], "user");
+}