diff --git a/src-tauri/src/proxy/providers/streaming_codex_chat.rs b/src-tauri/src/proxy/providers/streaming_codex_chat.rs
index 1146d095d..318fe36a9 100644
--- a/src-tauri/src/proxy/providers/streaming_codex_chat.rs
+++ b/src-tauri/src/proxy/providers/streaming_codex_chat.rs
@@ -801,7 +801,8 @@ impl ChatToResponsesState {
                 json!({
                     "input_tokens": 0,
                     "output_tokens": 0,
-                    "total_tokens": 0
+                    "total_tokens": 0,
+                    "output_tokens_details": { "reasoning_tokens": 0 }
                 })
             })
         })
diff --git a/src-tauri/src/proxy/providers/transform_codex_chat.rs b/src-tauri/src/proxy/providers/transform_codex_chat.rs
index a3568dce5..8720753c6 100644
--- a/src-tauri/src/proxy/providers/transform_codex_chat.rs
+++ b/src-tauri/src/proxy/providers/transform_codex_chat.rs
@@ -1507,7 +1507,8 @@ pub(crate) fn chat_usage_to_responses_usage(usage: Option<&Value>) -> Value {
         return json!({
             "input_tokens": 0,
             "output_tokens": 0,
-            "total_tokens": 0
+            "total_tokens": 0,
+            "output_tokens_details": { "reasoning_tokens": 0 }
         });
     };
 
@@ -1540,8 +1541,17 @@ pub(crate) fn chat_usage_to_responses_usage(usage: Option<&Value>) -> Value {
         result["input_tokens_details"] = json!({ "cached_tokens": cached });
     }
 
-    if let Some(details) = usage.get("completion_tokens_details") {
-        result["output_tokens_details"] = details.clone();
+    if let Some(details) = usage
+        .get("completion_tokens_details")
+        .filter(|v| v.is_object())
+    {
+        let mut details = details.clone();
+        if details.get("reasoning_tokens").is_none() {
+            details["reasoning_tokens"] = json!(0);
+        }
+        result["output_tokens_details"] = details;
+    } else {
+        result["output_tokens_details"] = json!({ "reasoning_tokens": 0 });
     }
 
     if let Some(cache_read) = usage.get("cache_read_input_tokens") {