feat: enable local docker demo mode

backend/app/services/adapters/demo.py

@@ -0,0 +1,151 @@
+"""Local deterministic demo adapters for portfolio Docker demos."""
+
+from __future__ import annotations
+
+from typing import Literal
+
+from app.services.adapters.base import BaseAdapter
+from app.services.adapters.registry import AdapterRegistry
+from app.services.adapters.storybook.primary import Storybook, StorybookPage
+from app.services.adapters.text.models import StoryOutput
+
+
+def _compact_topic(data: str) -> str:
+    parts = [
+        item.strip(" ，,。.!！?？")
+        for item in data.replace("\n", " ").split()
+        if item.strip(" ，,。.!！?？")
+    ]
+    if parts:
+        return "、".join(parts[:3])
+    return data.strip()[:20] or "星光森林"
+
+
+def _demo_image_data_url(label: str) -> str:
+    return (
+        "data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' "
+        "viewBox='0 0 1200 800'%3E%3Crect width='1200' height='800' "
+        "fill='%23fef3c7'/%3E%3Ccircle cx='250' cy='180' r='130' "
+        "fill='%23f59e0b'/%3E%3Cpath d='M120 600C320 420 520 700 "
+        "720 500S1020 420 1100 560' fill='none' stroke='%237c3aed' "
+        "stroke-width='42'/%3E%3C/svg%3E"
+    )
+
+
+@AdapterRegistry.register("text", "demo")
+class DemoTextAdapter(BaseAdapter[StoryOutput]):
+    """Generate a stable local story without external AI services."""
+
+    adapter_type = "text"
+    adapter_name = "demo"
+
+    async def execute(
+        self,
+        input_type: Literal["keywords", "full_story"],
+        data: str,
+        education_theme: str | None = None,
+        memory_context: str | None = None,
+        **kwargs,
+    ) -> StoryOutput:
+        theme = education_theme or "勇气与想象力"
+        topic = _compact_topic(data)
+        title = f"{topic}的晚安冒险"
+        protagonist = "小星"
+        if memory_context and "名字" in memory_context:
+            protagonist = "故事里的小朋友"
+
+        story_text = (
+            f"睡前，{protagonist}把“{topic}”写在一张小纸条上，轻轻放进枕头下面。"
+            f"月光刚好照进房间，纸条变成了一只会发光的小船，邀请{protagonist}去寻找"
+            f"关于“{theme}”的答案。\n\n"
+            f"小船穿过云朵河，来到一片会唱歌的森林。森林里的小鹿说：真正的勇敢不是"
+            f"一点也不害怕，而是害怕的时候，还愿意牵住朋友的手往前走。{protagonist}"
+            f"听完以后，把一颗星星种进土里，星星长成了照亮回家路的小灯。\n\n"
+            f"回到房间时，纸条已经变成了一枚金色书签。{protagonist}把它夹进故事书，"
+            f"决定明天也带着好奇心和温柔，继续新的冒险。"
+        )
+
+        return StoryOutput(
+            mode="generated" if input_type == "keywords" else "enhanced",
+            title=title,
+            story_text=story_text,
+            cover_prompt_suggestion=f"温暖水彩儿童绘本封面，主题：{topic}，{theme}",
+        )
+
+    async def health_check(self) -> bool:
+        return True
+
+    @property
+    def estimated_cost(self) -> float:
+        return 0.0
+
+
+@AdapterRegistry.register("image", "demo")
+class DemoImageAdapter(BaseAdapter[str]):
+    """Return a compact SVG data URL as a generated-image placeholder."""
+
+    adapter_type = "image"
+    adapter_name = "demo"
+
+    async def execute(self, prompt: str, **kwargs) -> str:
+        return _demo_image_data_url(prompt)
+
+    async def health_check(self) -> bool:
+        return True
+
+    @property
+    def estimated_cost(self) -> float:
+        return 0.0
+
+
+@AdapterRegistry.register("storybook", "demo")
+class DemoStorybookAdapter(BaseAdapter[Storybook]):
+    """Generate a stable local storybook without external AI services."""
+
+    adapter_type = "storybook"
+    adapter_name = "demo"
+
+    async def execute(
+        self,
+        keywords: str,
+        page_count: int = 6,
+        education_theme: str | None = None,
+        memory_context: str | None = None,
+        **kwargs,
+    ) -> Storybook:
+        theme = education_theme or "勇气"
+        topic = _compact_topic(keywords)
+        page_count = max(4, min(page_count, 8))
+        page_texts = [
+            f"小星在枕头下发现一张写着“{topic}”的星光地图。",
+            "地图带他来到云朵河边，一只小船正在等他上船。",
+            f"森林里的小鹿告诉他：{theme}藏在每一次温柔的选择里。",
+            "小星把一颗星星种进土里，星星长成了回家的灯。",
+            "他把今天的发现画进故事本，准备明天讲给家人听。",
+            "月亮轻轻合上窗帘，房间里只剩下甜甜的梦。",
+            "星光地图变成书签，陪他继续下一次冒险。",
+            "每个勇敢的小问题，都能长出一个温暖的故事。",
+        ]
+        pages = [
+            StorybookPage(
+                page_number=index + 1,
+                text=page_texts[index],
+                image_prompt=f"温暖儿童绘本插画，第 {index + 1} 页，{topic}，{theme}",
+            )
+            for index in range(page_count)
+        ]
+
+        return Storybook(
+            title=f"{topic}的星光绘本",
+            main_character="小星",
+            art_style="温暖水彩",
+            pages=pages,
+            cover_prompt=f"温暖水彩儿童绘本封面，{topic}，{theme}",
+        )
+
+    async def health_check(self) -> bool:
+        return True
+
+    @property
+    def estimated_cost(self) -> float:
+        return 0.0