Fix Studio auto-titles for reasoning models (#7098)

studio/frontend/src/features/chat/runtime-provider.tsx

@@ -77,6 +77,7 @@ const pendingRunStartReadyByMessageId = new Map<string, Promise<void>>();
 
 type TitleResponse = {
   choices?: Array<{
+    finish_reason?: string | null;
     message?: {
       content?: string;
     };
@@ -474,6 +475,8 @@ async function generateTitleWithModel(payload: {
       max_tokens: 24,
       top_k: 20,
       repetition_penalty: 1.0,
+      enable_thinking: false,
+      reasoning_effort: "none",
       messages: [
         {
           role: "system",
@@ -489,8 +492,10 @@ async function generateTitleWithModel(payload: {
     .json()
     .catch(() => null)) as TitleResponse | null;
   if (!response.ok) return null;
-  const raw: string | undefined = body?.choices?.[0]?.message?.content;
-  if (!raw) return null;
+  const choice = body?.choices?.[0];
+  if (choice?.finish_reason === "length") return null;
+  const raw: string | undefined = choice?.message?.content;
+  if (!raw || /<\/?think>/i.test(raw)) return null;
   return normalizeTitle(raw);
 }
 

tests/studio/test_chat_title_generation.py

@@ -65,6 +65,8 @@ def test_title_model_payload_includes_optional_assistant_reply():
     assert "if (assistant)" in block
     assert "parts.push(`Assistant: ${assistant}`);" in block
     assert 'parts.join("\\n")' in block
+    assert "enable_thinking: false" in block
+    assert 'reasoning_effort: "none"' in block
 
 
 def test_generate_title_passes_first_assistant_reply_after_first_user():
@@ -81,6 +83,25 @@ def test_generate_title_passes_first_assistant_reply_after_first_user():
     assert "assistantText," in block
 
 
+def test_tool_call_only_first_assistant_still_uses_first_user_message():
+    source = RUNTIME_TSX.read_text()
+    extract_block = " ".join(_balanced_block(source, "function extractTextParts").split())
+    generate_block = " ".join(_balanced_block(source, "async generateTitle(remoteId").split())
+
+    assert (
+        '.filter((p): p is Extract<typeof p, { type: "text" }> => p.type === "text")'
+        in extract_block
+    )
+    assert (
+        "const userText = extractTextParts(firstUser) || defaultTitle; const assistantText = extractTextParts(firstAssistant);"
+        in generate_block
+    )
+    assert (
+        "(await generateTitleWithModel({ userText, assistantText, })) || fallbackTitleFromUserText(userText);"
+        in generate_block
+    )
+
+
 def test_auto_title_disabled_uses_deterministic_user_text_fallback():
     block = _balanced_block(
         RUNTIME_TSX.read_text(),
@@ -93,12 +114,18 @@ def test_auto_title_disabled_uses_deterministic_user_text_fallback():
 
 
 def test_model_failure_still_falls_back_to_user_text():
-    block = _balanced_block(
-        RUNTIME_TSX.read_text(),
-        "async generateTitle(remoteId",
+    source = RUNTIME_TSX.read_text()
+    model_block = _source_until(
+        source,
+        "async function generateTitleWithModel",
+        "\nconst inflightTitleByKey",
     )
+    generate_block = _balanced_block(source, "async generateTitle(remoteId")
 
-    assert "})) || fallbackTitleFromUserText(userText);" in block
+    assert "finish_reason?: string | null;" in source
+    assert 'if (choice?.finish_reason === "length") return null;' in model_block
+    assert r"if (!raw || /<\/?think>/i.test(raw)) return null;" in model_block
+    assert "})) || fallbackTitleFromUserText(userText);" in generate_block
 
 
 def test_title_normalizer_still_enforces_output_constraints():
@@ -113,3 +140,4 @@ def test_title_normalizer_still_enforces_output_constraints():
     assert 'replace(/[.!?:;,]+/g, " ")' in block
     assert 'title.split(" ").filter(Boolean).slice(0, 6)' in block
     assert "joined.length > 60" in block
+    assert "return normalizeTitle(raw);" in block