From fedbcf7f867c4ba57921bf1011a1fe4058b7e359 Mon Sep 17 00:00:00 2001
From: Chang Wang <743976+cheapsteak@users.noreply.github.com>
Date: Mon, 11 May 2026 13:14:01 -0400
Subject: [PATCH] =?UTF-8?q?fix(codex):=20drop=20user=20parameter=20?=
 =?UTF-8?q?=E2=80=94=20ChatGPT=20backend=20rejects=20it?=
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The ChatGPT Codex backend (consumed via the Anthropic → Responses
translator) rejects requests that include a top-level `user` field with:

    HTTP 400 {"detail":"Unsupported parameter: user"}

Claude Code (and any Anthropic-protocol client that populates
`metadata.user_id`) hits this on every request, making the codex
provider unusable from Claude Code.

Drop the `metadata.user_id` → `user` forward in
`anthropicToResponsesRequest`. A comment is left in its place so the
constraint isn't accidentally re-added.
---
 src/upstream/responses-translator.ts | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/upstream/responses-translator.ts b/src/upstream/responses-translator.ts
index 930141c..11d468d 100644
--- a/src/upstream/responses-translator.ts
+++ b/src/upstream/responses-translator.ts
@@ -310,7 +310,9 @@ export function anthropicToResponsesRequest(body: any): any {
   if (body.max_tokens !== undefined) out.max_output_tokens = body.max_tokens;
   if (body.temperature !== undefined) out.temperature = body.temperature;
   if (body.top_p !== undefined) out.top_p = body.top_p;
-  if (body.metadata?.user_id) out.user = body.metadata.user_id;
+  // NOTE: Do not forward `metadata.user_id` as `user`. The ChatGPT Codex
+  // backend (the only consumer of this translator) rejects requests that
+  // include `user` with HTTP 400 `{"detail":"Unsupported parameter: user"}`.
 
   // Anthropic `system` can be a string or [{type:"text", text}] array.
   if (body.system) {