From 358c4d8385213e73b030ed8ef9385e7ade145128 Mon Sep 17 00:00:00 2001
From: akash-vijay-kv <akash@keyvalue.systems>
Date: Fri, 17 Jul 2026 01:19:01 +0530
Subject: [PATCH] feat: Add support for capturing cache-write tokens in OpenAI
 instrumentation

---
 src/instrumentation/utils.ts | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/instrumentation/utils.ts b/src/instrumentation/utils.ts
index ba5d43b..b411f52 100644
--- a/src/instrumentation/utils.ts
+++ b/src/instrumentation/utils.ts
@@ -585,7 +585,13 @@ function setUsageAttributes(
     );
   }
 
-  const cacheCreationTokens = usage.cache_creation_input_tokens;
+  const cacheCreationTokens =
+    usage.cache_creation_input_tokens ??
+    (
+      (usage.prompt_tokens_details ?? usage.input_tokens_details) as
+        | { cache_write_tokens?: unknown }
+        | undefined
+    )?.cache_write_tokens;
   if (cacheCreationTokens !== undefined) {
     span.setAttribute(
       SpanAttributes.LLM_USAGE_CACHE_CREATION_INPUT_TOKENS,