model_name error fix

src/ui/screens_shared.py

@@ -307,8 +307,9 @@ def screen_chat(s: dict, cfg: dict) -> None:
                 messages.append({"role": t["role"], "content": t["content"]})
             messages.append({"role": "user", "content": user_msg})
 
+            # Use per-item model name
+            item_cfg = {**cfg, "model_name": item.get("model_name", "")}
             with st.spinner("AI is responding…"):
-                item_cfg = {**cfg, "model_name": item["model_name"]}
                 ai_reply = call_model(messages, item_cfg)
 
             now       = time.time()
@@ -324,9 +325,9 @@ def screen_chat(s: dict, cfg: dict) -> None:
                 "role":       "assistant",
                 "content":    ai_reply,
                 "timestamp":  now,
-                "model":      cfg["model_name"],
+                "model":      item.get("model_name", ""),   # ← per-item, not cfg
             })
-            conv["num_turns"]              = num_turns + 1
+            conv["num_turns"]               = num_turns + 1
             s["items"][idx]["conversation"] = conv
             st.rerun()
 
@@ -364,7 +365,7 @@ def screen_post_rating(s: dict, cfg: dict) -> None:
         render_single_card(item["product"])
         question = "How **likely** are you to purchase this product now?"
 
-    choices = rating_choices(study_type)
+    choices  = rating_choices(study_type)
     post_val = st.radio(question, choices, index=None, key=f"post_rating_{idx}")
 
     if st.button("Next →", type="primary", use_container_width=True):
@@ -436,7 +437,6 @@ def screen_reflection(s: dict, cfg: dict) -> None:
             s["meta"] = {
                 "submission_time":  end_time,
                 "duration_seconds": round(end_time - s.get("start_time", end_time), 1),
-                "model":            cfg["model_name"],
                 "study_type":       cfg["study_type"],
             }
             with st.spinner("Saving your responses…"):
@@ -473,19 +473,19 @@ def screen_done(s: dict, cfg: dict) -> None:
 
         if study_type == "preference":
             rows.append({
-                "#":          i + 1,
-                "Category":   cat,
-                "Product A":  (item.get("product_a", {}).get("title", "") or "")[:45] + "…",
-                "Product B":  (item.get("product_b", {}).get("title", "") or "")[:45] + "…",
+                "#":           i + 1,
+                "Category":    cat,
+                "Product A":   (item.get("product_a", {}).get("title", "") or "")[:45] + "…",
+                "Product B":   (item.get("product_b", {}).get("title", "") or "")[:45] + "…",
                 "Pre-rating":  labels.get(pre,  str(pre)  if pre  is not None else "—"),
                 "Post-rating": labels.get(post, str(post) if post is not None else "—"),
                 "Shift":       f"{arrow} {delta:+d}" if isinstance(delta, int) else "—",
             })
         else:
             rows.append({
-                "#":          i + 1,
-                "Category":   cat,
-                "Product":    (item.get("product", {}).get("title", "") or "")[:65] + "…",
+                "#":           i + 1,
+                "Category":    cat,
+                "Product":     (item.get("product", {}).get("title", "") or "")[:65] + "…",
                 "Pre-rating":  labels.get(pre,  str(pre)  if pre  is not None else "—"),
                 "Post-rating": labels.get(post, str(post) if post is not None else "—"),
                 "Shift":       f"{arrow} {delta:+d}" if isinstance(delta, int) else "—",