fix: terminate invalid provider streams

apps/workshop/tests/openrouter-mock.mjs

@@ -81,6 +81,11 @@ const server = createServer(async (request, response) => {
     json(response, 503, { error: { message: "Simulated upstream failure" } });
     return;
   }
+  if (body.messages?.some((message) => message.content === "malformed stream")) {
+    response.writeHead(200, { "content-type": "text/event-stream" });
+    response.end('data: {"model":\n\n');
+    return;
+  }
   if (body.messages?.some((message) => message.content === "in-flight probe")) {
     await new Promise((resolve) => setTimeout(resolve, 500));
   }

apps/workshop/tests/workshop.integration.mjs

@@ -278,6 +278,24 @@ if (
 ) {
   throw new Error("The Homarr provider did not preserve the upstream SSE stream");
 }
+const malformedStreamResponse = await fetch(`${baseUrl}/api/ai/v1/chat/completions`, {
+  method: "POST",
+  headers: { "content-type": "application/json", ...concurrencySession.headers },
+  body: JSON.stringify({
+    model: "homarr/model",
+    messages: [{ role: "user", content: "malformed stream" }],
+    stream: true,
+  }),
+});
+const malformedStreamText = await malformedStreamResponse.text();
+if (
+  !malformedStreamResponse.ok ||
+  !malformedStreamText.includes('"type":"homarr_provider_error"') ||
+  malformedStreamText.includes('data: {"model":') ||
+  !malformedStreamText.endsWith("data: [DONE]\n\n")
+) {
+  throw new Error(`Malformed upstream streams did not terminate safely: ${malformedStreamText}`);
+}
 const toolResponse = await fetch(`${baseUrl}/api/ai/v1/chat/completions`, {
   method: "POST",
   headers: {