diff --git a/open-sse/utils/stream.js b/open-sse/utils/stream.js
index bcfff891..83f48713 100644
--- a/open-sse/utils/stream.js
+++ b/open-sse/utils/stream.js
@@ -253,6 +253,14 @@ export function createSSEStream(options = {}) {
             appendRequestLog({ model, provider, connectionId, tokens: null, status: "200 OK" }).catch(() => { });
           }
           
+          // IMPORTANT: In passthrough mode we still must terminate the SSE stream.
+          // Some clients (e.g. OpenClaw) expect the OpenAI-style sentinel:
+          //   data: [DONE]\n\n
+          // Without it they can hang until timeout and trigger failover.
+          const doneOutput = "data: [DONE]\n\n";
+          reqLogger?.appendConvertedChunk?.(doneOutput);
+          controller.enqueue(sharedEncoder.encode(doneOutput));
+
           if (onStreamComplete) {
             onStreamComplete({
               content: accumulatedContent,