Fix: respond() now returns history list pairs (tuples), not raw strings

app.py

@@ -53,7 +53,7 @@ def execute(tool_name: str, tool_args: dict) -> str:
 
 # ─── Response Logic ──────────────────────────────────────────────────────────
 
-def respond(message: str):
+def respond(message: str, history: list):
     msg = message.lower()
 
     if any(k in msg for k in ["calculate", "compute", "math", "roi", "compound", "interest", "%", "$"]):
@@ -69,12 +69,12 @@ def respond(message: str):
         cmd = m.group(1) if m else message.split()[-1]
         tool, args = "run_command", {"command": cmd, "cwd": "."}
     else:
-        return "This is a demo of Stack X Ultimate's tool-calling capability. The fine-tuned model processes your message and decides whether to call a tool. Try one of the examples below! 🔧"
+        return history + [[message, "This is a demo of Stack X Ultimate's tool-calling capability. The fine-tuned model processes your message and decides whether to call a tool. Try one of the examples below! 🔧"]]
 
     result = execute(tool, args)
     call = f"🔧 Calling `{tool}`...\n\n```json\n{json.dumps(args, indent=2)}\n```"
     res = f"✅ **{tool}** result:\n\n```\n{result}\n```"
-    return [[call, res]]
+    return history + [[call, res]]
 
 # ─── Dark CSS ─────────────────────────────────────────────────────────────