fix(commandcode): replay raw byte chunks to preserve all NDJSON lines

open-sse/executors/commandcode.js

@@ -141,7 +141,7 @@ export async function inspectAndWrapCommandCodeResponse(originalResponse, model)
   const reader = originalResponse.body.getReader();
   const decoder = new TextDecoder();
   let buffer = "";
-  const bufferedLines = [];
+  const rawChunks = [];
   let detectedError = null;
 
   try {
@@ -155,16 +155,15 @@ export async function inspectAndWrapCommandCodeResponse(originalResponse, model)
             const parsed = JSON.parse(jsonStr);
             if (parsed?.type === "error") {
               detectedError = parsed;
-            } else {
-              bufferedLines.push(trimmed);
             }
           } catch {
-            bufferedLines.push(trimmed);
+            /* ignore */
           }
         }
         break;
       }
 
+      rawChunks.push(value);
       buffer += decoder.decode(value, { stream: true });
       const lines = buffer.split("\n");
       buffer = lines.pop() || "";
@@ -175,7 +174,6 @@ export async function inspectAndWrapCommandCodeResponse(originalResponse, model)
         if (!trimmed) continue;
         const jsonStr = trimmed.startsWith("data:") ? trimmed.slice(5).trim() : trimmed;
         if (!jsonStr || jsonStr === "[DONE]") {
-          bufferedLines.push(trimmed);
           stopLoop = true;
           break;
         }
@@ -184,7 +182,6 @@ export async function inspectAndWrapCommandCodeResponse(originalResponse, model)
         try {
           event = JSON.parse(jsonStr);
         } catch {
-          bufferedLines.push(trimmed);
           continue;
         }
 
@@ -194,8 +191,6 @@ export async function inspectAndWrapCommandCodeResponse(originalResponse, model)
           break;
         }
 
-        bufferedLines.push(trimmed);
-
         if (
           event?.type === "text-delta" ||
           event?.type === "reasoning-delta" ||
@@ -238,29 +233,18 @@ export async function inspectAndWrapCommandCodeResponse(originalResponse, model)
     );
   }
 
-  const combinedStream = createReplayedStream(bufferedLines, buffer, reader);
+  const combinedStream = createRawReplayedStream(rawChunks, reader);
   return wrapNdjsonAsOpenAISse(combinedStream, model, originalResponse);
 }
 
-function createReplayedStream(bufferedLines, remainingBuffer, reader) {
-  const encoder = new TextEncoder();
-  let replayed = false;
+function createRawReplayedStream(rawChunks, reader) {
+  let chunkIndex = 0;
 
   return new ReadableStream({
     async pull(controller) {
-      if (!replayed) {
-        replayed = true;
-        let prefix = bufferedLines.join("\n");
-        if (prefix && remainingBuffer) {
-          prefix += "\n" + remainingBuffer;
-        } else if (remainingBuffer) {
-          prefix = remainingBuffer;
-        } else if (prefix) {
-          prefix += "\n";
-        }
-        if (prefix) {
-          controller.enqueue(encoder.encode(prefix));
-        }
+      if (chunkIndex < rawChunks.length) {
+        controller.enqueue(rawChunks[chunkIndex++]);
+        return;
       }
 
       try {

tests/unit/commandcode-executor.test.js

@@ -133,6 +133,30 @@ describe("inspectAndWrapCommandCodeResponse", () => {
     expect(text).toContain("data: [DONE]");
   });
 
+  it("preserves all lines in a multi-line packet when inspecting tool-input-start", async () => {
+    const packet = [
+      JSON.stringify({ type: "start" }),
+      JSON.stringify({ type: "start-step" }),
+      JSON.stringify({ type: "tool-input-start", id: "call_1", toolName: "terminal" }),
+      JSON.stringify({ type: "tool-input-delta", id: "call_1", delta: '{"command": "ls"}' }),
+      JSON.stringify({ type: "finish-step", finishReason: "tool-calls" }),
+      JSON.stringify({ type: "finish", finishReason: "tool-calls" }),
+    ].join("\n") + "\n";
+
+    const ndjsonBody = createNdjsonStream([packet]);
+
+    const fakeResponse = new Response(ndjsonBody, {
+      status: 200,
+      headers: { "Content-Type": "text/event-stream" },
+    });
+
+    const result = await inspectAndWrapCommandCodeResponse(fakeResponse, "cmc/deepseek/deepseek-v4.1-flash");
+    expect(result.ok).toBe(true);
+    const text = await result.text();
+    expect(text).toContain('"name":"terminal"');
+    expect(text).toContain('"arguments":"{\\"command\\": \\"ls\\"}"');
+  });
+
   it("retries when initial stream yields an error and succeeds on second attempt", async () => {
     let callCount = 0;
     const executor = new CommandCodeExecutor();