Normalize product data prompt formatting

skills/product-data/scripts/product_data_portable.py

@@ -651,12 +651,15 @@ def build_planning_prompt(
 ) -> str:
     """把训练 instruction 包成评测侧使用的 chat template。"""
 
-    instruction = build_training_instruction(
-        record,
-        session_num=session_num,
-        session_time_minutes=session_time_minutes,
-        context_fields=context_fields,
+    instruction = prompt_section_with_one_trailing_newline(
+        build_training_instruction(
+            record,
+            session_num=session_num,
+            session_time_minutes=session_time_minutes,
+            context_fields=context_fields,
+        )
     )
+    system_prompt = prompt_section_without_trailing_newline(system_prompt)
     return (
         f"<|im_start|>system\n{system_prompt}<|im_end|>\n"
         f"<|im_start|>user\n{instruction}<|im_end|>\n"
@@ -664,6 +667,14 @@ def build_planning_prompt(
     )
 
 
+def prompt_section_without_trailing_newline(text: str) -> str:
+    return str(text or "").rstrip("\n")
+
+
+def prompt_section_with_one_trailing_newline(text: str) -> str:
+    return prompt_section_without_trailing_newline(text) + "\n"
+
+
 def training_jsonl_line(
     record: dict[str, Any],
     *,
@@ -673,7 +684,7 @@ def training_jsonl_line(
     system_prompt: str,
 ) -> str:
     payload = {
-        "system": system_prompt,
+        "system": prompt_section_without_trailing_newline(system_prompt),
         "instruction": build_training_instruction(
             record,
             session_num=session_num,