diff --git a/extensions/codex/src/conversation-binding.test.ts b/extensions/codex/src/conversation-binding.test.ts
index 9a98f3d81129..b95fd54e766c 100644
--- a/extensions/codex/src/conversation-binding.test.ts
+++ b/extensions/codex/src/conversation-binding.test.ts
@@ -2405,6 +2405,7 @@ describe("codex conversation binding", () => {
         threadId: "thread-old",
         cwd: "/old-repo",
         conversationStartId: "start-old",
+        reasoningEffort: "high",
       },
     });
     const requests: Array<{ method: string; params: Record<string, unknown> }> = [];
@@ -2477,6 +2478,7 @@ describe("codex conversation binding", () => {
       threadId: "thread-target",
       cwd: "/new-repo",
       conversationStartId: "start-new",
+      reasoningEffort: "high",
     });
   });
 
diff --git a/extensions/codex/src/conversation-binding.ts b/extensions/codex/src/conversation-binding.ts
index 160c4ce39c02..77ca23bdde4e 100644
--- a/extensions/codex/src/conversation-binding.ts
+++ b/extensions/codex/src/conversation-binding.ts
@@ -664,7 +664,10 @@ async function writeThreadBindingFromResponse(
         cwd: params.workspaceDir,
         authProfileId: params.authProfileId,
         model: response.model ?? resolved.model ?? params.model,
-        reasoningEffort: response.reasoningEffort,
+        reasoningEffort: resolveCodexBindingReasoningEffort(
+          response.reasoningEffort,
+          current?.reasoningEffort,
+        ),
         modelProvider: normalizeCodexAppServerBindingModelProvider({
           authProfileId: params.authProfileId,
           modelProvider: response.modelProvider ?? resolved.modelProvider ?? params.modelProvider,