feat: 试用过程中的细节优化

server/services/prompts/google.py

@@ -98,12 +98,13 @@ def _task_ecommerce_detail(ctx: dict, lang: str) -> str:
 
 def _task_size_chart(ctx: dict, lang: str) -> str:
     dims = params_line_for_output(ctx, lang)
+    annotation = ctx.get("dimension_annotation_instruction") or "Do not invent measurement directions or values."
     return (
         "Create a size chart: the unchanged product in clean front and side views on a light background, "
-        "thin measurement annotation lines (arrows) marking length, width and height with values beside "
+        "thin measurement annotation lines (arrows) only for supplied dimensions with values beside "
         "each line"
         + (f" (known specs: {dims})" if dims else "")
-        + ", small caption row, precise technical-drawing aesthetic."
+        + f". {annotation} Small caption row, precise technical-drawing aesthetic."
     )
 
 def _task_sku_collection(ctx: dict, lang: str) -> str:
@@ -128,8 +129,19 @@ _TASK_BUILDERS = {
 
 
 def build_prompt(type_id: str, ctx: dict, style_set: int, lang: str, extra: dict | None = None,
-                 style_prompt: str | None = None, requirements: str | None = None) -> str:
+                 style_prompt: str | None = None, requirements: str | None = None,
+                 requirements_exclusive: bool = False) -> str:
     """构造指定图类型的 prompt：要求块 → 指令 → 主体锁 → 锚定 → 风格 → 文案 → 画质 → 提醒。"""
+    if requirements_exclusive:
+        return "\n\n".join([
+            requirements_block(requirements),
+            "Edit the first image only as required above. Do not add marketing layouts, captions, overlays, "
+            "props, default studio styling, or visible text unless explicitly requested above.",
+            "PROTECTION: preserve the first image exactly unless the strict requirements explicitly request "
+            "a specific change. When they do, make only that requested change and preserve everything else.",
+            "Final check: follow the strict requirements over every default behavior; do not make changes "
+            "that were not explicitly required.",
+        ])
     style = resolve_style(style_set, style_prompt)
     extra = extra or {}
     hint = (extra.get("prompt_hint") or "").strip()