From 8b556de03b3f1c5503223ab8ff5e528e9180fb08 Mon Sep 17 00:00:00 2001
From: diegosouzapw <diegosouzapw@users.noreply.github.com>
Date: Sat, 21 Mar 2026 17:09:13 -0300
Subject: [PATCH] fix: preserve prompt_cache_key in Responses API translation,
 escape \n in tagContent (#517, #515)
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fix(translator): preserve prompt_cache_key when translating Responses API requests
  (#517) — prompt_cache_key is an account-affinity signal used by Codex for
  prompt cache routing. Deleting it from the translated request prevented full
  cache effectiveness. Removed delete from openai-responses.ts and
  responsesApiHelper.ts cleanup blocks.

fix(combo): escape \n in tagContent so injected JSON string is valid (#515)
  — omniModel tag content used template literal newlines (U+000A) which produce
  unescaped newline chars inside a JSON string value. Replaced with literal \n
  escape sequences for valid JSON injection in streaming SSE content chunks.
---
 open-sse/services/combo.ts                        | 2 +-
 open-sse/translator/helpers/responsesApiHelper.ts | 3 ++-
 open-sse/translator/request/openai-responses.ts   | 3 ++-
 3 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/open-sse/services/combo.ts b/open-sse/services/combo.ts
index 8dc2e99668..a8963b1a4d 100644
--- a/open-sse/services/combo.ts
+++ b/open-sse/services/combo.ts
@@ -472,7 +472,7 @@ export async function handleComboChat({
         // SDKs close the connection on finish_reason, so anything sent after
         // that marker is silently dropped.
         if (!res.body) return res;
-        const tagContent = `\n<omniModel>${modelStr}</omniModel>\n`;
+        const tagContent = `\\n<omniModel>${modelStr}</omniModel>\\n`;
         const encoder = new TextEncoder();
         const decoder = new TextDecoder();
         let tagInjected = false;
diff --git a/open-sse/translator/helpers/responsesApiHelper.ts b/open-sse/translator/helpers/responsesApiHelper.ts
index 0d65111ebf..01967f6fd0 100644
--- a/open-sse/translator/helpers/responsesApiHelper.ts
+++ b/open-sse/translator/helpers/responsesApiHelper.ts
@@ -93,10 +93,11 @@ export function convertResponsesApiFormat(body) {
   }
 
   // Cleanup Responses API specific fields
+  // Note: prompt_cache_key is intentionally preserved — it is used by Codex and other
+  // providers as a cache-affinity signal. Stripping it breaks prompt caching (#517).
   delete result.input;
   delete result.instructions;
   delete result.include;
-  delete result.prompt_cache_key;
   delete result.store;
   delete result.reasoning;
 
diff --git a/open-sse/translator/request/openai-responses.ts b/open-sse/translator/request/openai-responses.ts
index 239c547562..11fcbe86aa 100644
--- a/open-sse/translator/request/openai-responses.ts
+++ b/open-sse/translator/request/openai-responses.ts
@@ -227,10 +227,11 @@ export function openaiResponsesToOpenAIRequest(
   });
 
   // Cleanup Responses API specific fields
+  // Note: prompt_cache_key is intentionally preserved — it is used by Codex and other
+  // providers as a cache-affinity signal. Stripping it breaks prompt caching (#517).
   delete result.input;
   delete result.instructions;
   delete result.include;
-  delete result.prompt_cache_key;
   delete result.store;
   delete result.reasoning;