fix(stream): suppress compact malformed tool calls

open-sse/utils/stream.ts

@@ -241,6 +241,11 @@ function containsTextualToolCallCandidate(text: unknown): boolean {
   return parseTextualToolCallCandidate(text) !== null;
 }
 
+function containsMalformedTextualToolCall(text: unknown): boolean {
+  if (typeof text !== "string") return false;
+  return text.replace(/[\u200B-\u200D\uFEFF]/g, "").includes("[Tool call:");
+}
+
 function collectPassthroughTextualToolCall(
   text: string,
   toolCalls: Map<string, ToolCall>
@@ -1746,6 +1751,8 @@ export function createSSEStream(options: StreamOptions = {}) {
                 if (content && collectPassthroughTextualToolCall(content, passthroughToolCalls)) {
                   passthroughHasToolCalls = true;
                   content = "";
+                } else if (containsMalformedTextualToolCall(content)) {
+                  content = "";
                 }
                 const message: Record<string, unknown> = {
                   role: "assistant",
@@ -1987,6 +1994,8 @@ export function createSSEStream(options: StreamOptions = {}) {
                   },
                 });
                 content = "";
+              } else if (containsMalformedTextualToolCall(content)) {
+                content = "";
               }
               const message: Record<string, unknown> = {
                 role: "assistant",

tests/unit/stream-utils.test.ts

@@ -267,6 +267,46 @@ test("createSSEStream passthrough suppresses malformed textual tool-call content
   assert.doesNotMatch(JSON.stringify(onCompletePayload.responseBody), /\[Tool call: terminal\]/);
 });
 
+test("createSSEStream suppresses malformed compact textual tool-call content", async () => {
+  let onCompletePayload = null;
+
+  const text = await readTransformed(
+    [
+      `data: ${JSON.stringify({
+        candidates: [
+          {
+            content: {
+              parts: [
+                {
+                  text: "[Tool call: search_files_ide{file_glob:*combos*.ts,path:/opt/OmniRoute,target:files}]",
+                },
+              ],
+            },
+          },
+        ],
+      })}\n\n`,
+      `data: ${JSON.stringify({ candidates: [{ finishReason: "STOP" }] })}\n\n`,
+    ],
+    {
+      mode: "translate",
+      targetFormat: FORMATS.ANTIGRAVITY,
+      sourceFormat: FORMATS.OPENAI,
+      provider: "antigravity",
+      model: "antigravity/gemini-3.5-flash-low",
+      body: { messages: [{ role: "user", content: "inspect files" }] },
+      onComplete(payload) {
+        onCompletePayload = payload;
+      },
+    }
+  );
+
+  const choice = onCompletePayload.responseBody.choices[0];
+  assert.equal(choice.finish_reason, "stop");
+  assert.equal(choice.message.content, null);
+  assert.equal(choice.message.tool_calls, undefined);
+  assert.doesNotMatch(JSON.stringify(onCompletePayload.responseBody), /\[Tool call:/);
+});
+
 test("createSSEStream passthrough flushes a buffered final line without a trailing newline", async () => {
   const text = await readTransformed(
     [