Add demo trading analyst with plan validation and sizing

The analyst prompts the model with trading rules, published skills,
account sizing inputs and prefetched market data, exposes read-only
tools plus submit_trade_plan, and validates and sizes the submitted plan
in pure functions covered by pytest. Manual analyses run as dry runs
while trading is stopped; the trading page shows the latest plan and an
analysis detail drawer.

backend/src/alphapulse/ai/llm.py

@@ -31,6 +31,8 @@ MAX_RETRIES = 2
 # 这些都由这里再重试，且只在还没有输出内容时重试
 STREAM_RETRIES = 3
 STREAM_RETRY_DELAY_SECONDS = 2
+# 输出被截断时回给模型的工具结果：参数不完整，不能执行
+TRUNCATED_RESULT = json.dumps({"error": "输出达到最大输出上限被截断，工具参数不完整，未执行。请精简内容后重新调用"}, ensure_ascii=False)
 
 logger = logging.getLogger("alphapulse.ai.llm")
 

backend/src/alphapulse/ai/prompt.py

@@ -50,14 +50,18 @@ async def data_overview(session: AsyncSession) -> str:
     return "\n".join(lines)
 
 
-async def build_system_prompt(session: AsyncSession) -> str:
-    parts = [BASE_INSTRUCTIONS, "## 数据概况", await data_overview(session)]
+async def skills_section(session: AsyncSession) -> str:
     skills = await published_skills(session)
-    parts.append("## Skills（按优先级从高到低）")
+    parts = ["## Skills（按优先级从高到低）"]
     if skills:
         parts += [f"### 【优先级 {info.node.priority}】{info.path}\n\n{content}" for info, content in skills]
     else:
         parts.append("（暂无已发布的 skill）")
+    return "\n\n".join(parts)
+
+
+async def build_system_prompt(session: AsyncSession) -> str:
+    parts = [BASE_INSTRUCTIONS, "## 数据概况", await data_overview(session), await skills_section(session)]
     context = await current_context(session)
     parts += ["## CONTEXT.md", context.content if context and context.content.strip() else "（空）"]
     return "\n\n".join(parts)