Upload engine.py

engine.py

@@ -3,6 +3,7 @@ import os
 from functools import lru_cache
 from openai import OpenAI
 from datetime import datetime
+import re
 
 # =========================
 # CONFIG
@@ -137,6 +138,19 @@ def build_join_sql(base_table, steps):
 
     return "\n".join(sql)
 
+# =========================
+# JSON SAFETY
+# =========================
+
+def safe_json_loads(text):
+    try:
+        return json.loads(text)
+    except json.JSONDecodeError:
+        match = re.search(r"\{.*\}", text, re.S)
+        if match:
+            return json.loads(match.group())
+        raise ValueError("LLM returned invalid JSON")
+
 
 # =========================
 # INTENT PARSING (LLM)
@@ -177,10 +191,14 @@ User question:
 """
 
     res = client.chat.completions.create(
-        model="gpt-4.1-mini",
-        messages=[{"role": "user", "content": prompt}],
-        temperature=0
-    )
+    model="gpt-4.1-mini",
+    messages=[
+        {"role": "system", "content": "You are a JSON-only API. Return valid JSON only."},
+        {"role": "user", "content": prompt}
+    ],
+    temperature=0
+)
+
 
     # ✅ Safe JSON parsing
     try: