Run demo trading and allocate capital per symbol

Move running, running_changed_at and capital_usdt from the account to
each trading symbol; the migration copies the account capital to every
symbol and leaves them all stopped. Each symbol is sized against its
own capital with a 3x notional cap, and the capitals together must not
exceed account equity. Scheduling, dry-run decisions and the executor
follow the per-symbol flag. The global start/stop button is replaced by
start/stop and capital controls on each symbol's plan card.

backend/src/alphapulse/trading/analyst.py

@@ -64,7 +64,7 @@ INSTRUCTIONS = f"""你是 AlphaPulse 的模拟盘交易分析器：为一个币
 - 止损：区间远端外 {rules.STOP_ATR_FACTOR}×ATR14(5m)，做多放在 zone_low 下方，做空放在 zone_high 上方；且距挂单价至少 {rules.MIN_STOP_ATR}×ATR14(5m)，挂单价贴近远端时按这条算。
 - 止盈：按成交均价，做多 {_ladder("long")}；做空 {_ladder("short")}。止盈 1 成交后撤销未成交的入场部分，止损移到保本价。
 - 首次成交后最长持仓 {rules.MAX_HOLD_HOURS} 小时，到时市价平仓。平仓后程序会请你重新分析。
-- 仓位：单笔风险为交易资金的 {_pct(rules.RISK_PCT)}，置信度低时减半；名义仓位合计不超过 {rules.MAX_LEVERAGE} 倍交易资金。
+- 仓位：单笔风险为该币交易资金的 {_pct(rules.RISK_PCT)}，置信度低时减半；名义仓位不超过 {rules.MAX_LEVERAGE} 倍该币交易资金。
 - reevaluate：任一条件满足时程序重新请你分析（最多 {rules.MAX_REEVALUATE} 个），用来表达另一侧方向、需要重新划区的位置。
 
 ## 程序的硬性校验
@@ -137,15 +137,16 @@ async def prepare(symbol: str, reasons: list[str], analysis_id: int) -> Prepared
         target = await session.get(TradingSymbol, symbol)
         if target is None:
             raise AnalysisError(f"{symbol} 已不在交易列表中")
-        if account is None or account.capital_usdt is None:
-            raise AnalysisError("还没有设置交易资金")
+        if account is None:
+            raise AnalysisError("还没有填写模拟盘 key")
+        if target.capital_usdt is None:
+            raise AnalysisError(f"{symbol} 还没有设置交易资金")
         provider = await session.get(AiProvider, account.provider_id) if account.provider_id else await session.scalar(
             select(AiProvider).where(AiProvider.is_default)
         )
         if provider is None:
             raise AnalysisError("没有可用的模型配置，请先到「环境变量」页面添加")
         session.expunge(provider)
-        symbols = list((await session.scalars(select(TradingSymbol.symbol))).all())
         recent = (await session.scalars(
             select(TradingAnalysis)
             .where(TradingAnalysis.symbol == symbol, TradingAnalysis.status == "done", TradingAnalysis.id != analysis_id)
@@ -163,20 +164,20 @@ async def prepare(symbol: str, reasons: list[str], analysis_id: int) -> Prepared
             )).all()
         ] if current else []
         system = "\n\n".join([INSTRUCTIONS, "## 数据概况", await data_overview(session), await skills_section(session)])
-        dry_run = not account.running
+        dry_run = not target.running
+        capital_usdt = target.capital_usdt
         effort = account.reasoning_effort or provider.reasoning_effort
 
     snapshot = await read_snapshot()
     if not snapshot or not snapshot["account"]:
         raise AnalysisError("取不到模拟盘账户快照（引擎未同步到币安），无法计算仓位")
     equity = Decimal(snapshot["account"]["margin_balance"])
-    capital = min(account.capital_usdt, equity)
+    capital = min(capital_usdt, equity)
     position = next((p for p in snapshot["positions"] if p["symbol"] == symbol), None)
-    other_notional = sum((Decimal(p["notional"]) for p in snapshot["positions"] if p["symbol"] != symbol and p["symbol"] in symbols), Decimal(0))
     symbol_rules_ = await symbol_rules(symbol)
     mark = await mark_price(symbol)
     context = PlanContext(
-        mark_price=mark, capital=capital, other_notional=other_notional, rules=symbol_rules_, atr=await recent_atr(symbol),
+        mark_price=mark, capital=capital, rules=symbol_rules_, atr=await recent_atr(symbol),
         has_plan=current is not None, position_side=position_side(snapshot, symbol),
     )
 
@@ -186,12 +187,12 @@ async def prepare(symbol: str, reasons: list[str], analysis_id: int) -> Prepared
         "## 任务",
         f"- 币种：{symbol}（币安 U 本位永续）",
         f"- 触发原因：{'；'.join(reasons)}",
-        f"- 运行模式：{'试运行（引擎已停止，计划只记录、不下单）' if dry_run else '交易中（计划会在模拟盘执行）'}",
+        f"- 运行模式：{'试运行（该币未在交易，计划只记录、不下单）' if dry_run else '交易中（计划会在模拟盘执行）'}",
         "",
         "## 账户（程序据此计算数量）",
-        f"- 交易资金：{capital:.2f} USDT（设定 {account.capital_usdt} USDT，账户权益 {equity:.2f} USDT，取较小者）",
+        f"- 该币交易资金：{capital:.2f} USDT（设定 {capital_usdt} USDT，账户权益 {equity:.2f} USDT，取较小者）",
         f"- 本次单笔风险金额：{risk:.2f} USDT（{_pct(rules.RISK_PCT)}；置信度低时 {risk * rules.LOW_CONFIDENCE_FACTOR:.2f}）",
-        f"- 可用名义仓位：{capital * rules.MAX_LEVERAGE - other_notional:.2f} USDT（{rules.MAX_LEVERAGE} 倍交易资金减去交易列表其他币的持仓 {other_notional:.2f}）",
+        f"- 名义仓位上限：{capital * rules.MAX_LEVERAGE:.2f} USDT（{rules.MAX_LEVERAGE} 倍该币交易资金）",
         f"- 模拟盘交易规则：价格精度 {symbol_rules_.tick_size}，数量精度 {symbol_rules_.step_size}，最小下单金额 {symbol_rules_.min_notional} USDT",
         f"- 模拟盘标记价：{mark}（校验以此为准；行情数据来自实盘，两者通常相差不到 0.1%）",
         f"- 最近已收盘 5m K 线的 ATR14：{context.atr:.{max(0, -symbol_rules_.tick_size.as_tuple().exponent)}f}（程序按它计算止损）",
@@ -266,8 +267,8 @@ async def submit(prepared: Prepared, symbol: str, analysis_id: int, arguments: d
 async def run_analysis(symbol: str, reasons: list[str]) -> None:
     """一次完整的分析；结果和失败原因都写进 trading_analyses 和时间线，不向外抛出"""
     async with SessionLocal() as session:
-        account = await session.get(TradingAccount, 1)
-        analysis = TradingAnalysis(symbol=symbol, reasons=reasons, dry_run=not (account and account.running), status="running")
+        target = await session.get(TradingSymbol, symbol)
+        analysis = TradingAnalysis(symbol=symbol, reasons=reasons, dry_run=not (target and target.running), status="running")
         session.add(analysis)
         await session.commit()
         analysis_id, dry_run = analysis.id, analysis.dry_run