refactor: simplify session title fallback to static 'Open Claude'

src/utils/sessionTitle.ts

@@ -125,28 +125,9 @@ export async function generateSessionTitle(
     })
     logEvent('tengu_session_title_generated', { success: false })
 
-    // Fallback: derive a title locally from the user's first message.
-    // This ensures 3P providers (Ollama, Gemini, OpenAI) still get
-    // meaningful terminal titles when the Haiku API call is unavailable.
-    return localFallbackTitle(trimmed)
+    // Fallback: When using 3P providers without a compatible schema,
+    // default to the application name.
+    return 'Open Claude'
   }
 }
 
-/**
- * Fallback local title generator for when the Haiku API is unavailable
- * (e.g. when using third-party providers without an Anthropic API key).
- */
-function localFallbackTitle(text: string): string | null {
-  const words = text.split(/\s+/).slice(0, 7)
-  if (words.length === 0) return null
-
-  // Create a sentence-case string
-  let fallback = words.join(' ')
-  if (fallback.length > 50) {
-    fallback = fallback.substring(0, 49) + '…'
-  }
-
-  if (fallback.length <= 3) return null
-
-  return fallback.charAt(0).toUpperCase() + fallback.slice(1)
-}