diff --git a/open-sse/handlers/responseSanitizer.ts b/open-sse/handlers/responseSanitizer.ts
index 780bb8afe8..76500b1840 100644
--- a/open-sse/handlers/responseSanitizer.ts
+++ b/open-sse/handlers/responseSanitizer.ts
@@ -231,6 +231,17 @@ function sanitizeUsage(usage: unknown): unknown {
   if (!usageRecord) return usage;
 
   const sanitized: JsonRecord = {};
+
+  // Cross-map Claude-style → OpenAI-style field names.
+  // Some providers return input_tokens/output_tokens instead of prompt_tokens/completion_tokens.
+  // Without this mapping, the whitelist filter below strips them, resulting in NaN/0 tokens (#617).
+  if (usageRecord.input_tokens !== undefined && usageRecord.prompt_tokens === undefined) {
+    usageRecord.prompt_tokens = usageRecord.input_tokens;
+  }
+  if (usageRecord.output_tokens !== undefined && usageRecord.completion_tokens === undefined) {
+    usageRecord.completion_tokens = usageRecord.output_tokens;
+  }
+
   for (const key of ALLOWED_USAGE_FIELDS) {
     if (usageRecord[key] !== undefined) {
       sanitized[key] = usageRecord[key];
diff --git a/package-lock.json b/package-lock.json
index 228bbd53fb..79a11f948f 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -19810,9 +19810,9 @@
       "license": "ISC"
     },
     "node_modules/yaml": {
-      "version": "2.8.2",
-      "resolved": "https://registry.npmjs.org/yaml/-/yaml-2.8.2.tgz",
-      "integrity": "sha512-mplynKqc1C2hTVYxd0PU2xQAc22TI1vShAYGksCCfxbn/dFwnHTNi1bvYsBTkhdUNtGIf5xNOg938rrSSYvS9A==",
+      "version": "2.8.3",
+      "resolved": "https://registry.npmjs.org/yaml/-/yaml-2.8.3.tgz",
+      "integrity": "sha512-AvbaCLOO2Otw/lW5bmh9d/WEdcDFdQp2Z2ZUH3pX9U2ihyUY0nvLv7J6TrWowklRGPYbB/IuIMfYgxaCPg5Bpg==",
       "dev": true,
       "license": "ISC",
       "bin": {