feat(warning-p0a): 资金缺口阈值外置 + 复算对拍 + 讲人话(数字守恒) + 数据就绪核验

P0-A（任务 fullstack-20261017-warning-capability-build-p0）：
- cash_thresholds.py：阈值迁 per-entity（复用 alert_rules.rule_type=cash_gap_threshold，
  默认 20/10 万不动；无配置/非法/异常一律回落默认，fail-safe 不改预警行为）
- cash_forecast_engine.py：阈值改从配置读取，响应新增 threshold_source 明写来源
- verify_cash_gap_replay.py：同输入双跑逐字段 diff=0 + 手算 3/3 + 端点逐字段对拍(--live)
- cash_gap_narrative.py：复用 ai_brief.call_deepseek，只写原因/建议；
  断言生成文本数字集合 ⊆ 规则层数字集合，违例即不带文案上线
- audit_warning_data_readiness.py：G0 只读核验（cma_reader SELECT only），
  行数/期间/枚举 + 数据质量缺口（期初全 0、负期末、单批次、无员工维度表）

未 push（push 即部署，须项目侧书面放行）；未改生产库/未动 cron。

backend/app/utils/cash_forecast_engine.py

@@ -13,9 +13,17 @@ if TYPE_CHECKING:
 
 logger = logging.getLogger("cma.cash_forecast")
 
-# 默认现金阈值（万元）
-DEFAULT_CASH_WARNING = 20.0   # 黄灯 — 低于20万
-DEFAULT_CASH_CRITICAL = 10.0  # 红灯 — 低于10万
+# 默认现金阈值（万元）—— 单一事实源迁至 app/utils/cash_thresholds.py（G1，2026-10-17）
+# 此处保留同名常量以兼容既有 import（app/api/cash.py 等）；数值未变：黄 20 / 红 10。
+from app.utils.cash_thresholds import (  # noqa: E402
+    DEFAULT_CRITICAL as _CFG_DEFAULT_CRITICAL,
+    DEFAULT_WARNING as _CFG_DEFAULT_WARNING,
+    get_cash_gap_thresholds,
+    describe_source as describe_cash_threshold_source,
+)
+
+DEFAULT_CASH_WARNING = _CFG_DEFAULT_WARNING   # 黄灯 — 低于20万
+DEFAULT_CASH_CRITICAL = _CFG_DEFAULT_CRITICAL  # 红灯 — 低于10万
 
 # 历史KPI编码映射（含候选编码，兼容F_*标准编码）
 KPI_CODES = {
@@ -306,17 +314,27 @@ def forecast_cash_flow(
     db: Session,
     days: int = 30,
     current_cash: Optional[float] = None,
+    warning_line: Optional[float] = None,
+    critical_line: Optional[float] = None,
 ) -> dict:
     """
     预测未来30天现金流
-    
+
     算法：
     1. 获取历史经营现金流、应收、应付趋势
     2. 推算每日现金流入/流出
     3. 生成每日预测值+置信区间
+
+    阈值（G1，2026-10-17）：warning_line / critical_line 传 None 时取本账套配置
+    （alert_rules: cash_gap_threshold），未配置则默认 20/10 万；显式传入优先（便于复算对拍）。
     """
     from app.models import KPIDefinition, KPIValue
 
+    if warning_line is None or critical_line is None:
+        cfg_warning, cfg_critical = get_cash_gap_thresholds(db, entity_id)
+        warning_line = cfg_warning if warning_line is None else warning_line
+        critical_line = cfg_critical if critical_line is None else critical_line
+
     # 获取当前现金余额
     if current_cash is None:
         base_cash = get_current_cash_balance(db, entity_id)
@@ -375,9 +393,9 @@ def forecast_cash_flow(
         upper = cash + std * 0.5
 
         # 预警状态
-        if cash < DEFAULT_CASH_CRITICAL:
+        if cash < critical_line:
             status = "red"
-        elif cash < DEFAULT_CASH_WARNING:
+        elif cash < warning_line:
             status = "yellow"
         else:
             status = "green"
@@ -396,20 +414,20 @@ def forecast_cash_flow(
     min_date = next(f["date"] for f in forecast if f["predicted_cash"] == min_cash)
 
     suggestions = []
-    if min_cash < DEFAULT_CASH_CRITICAL:
+    if min_cash < critical_line:
         suggestions.append({
             "type": "critical",
-            "message": f"预计{min_date}现金余额降至{min_cash:.1f}万，低于警戒线{DEFAULT_CASH_CRITICAL}万",
+            "message": f"预计{min_date}现金余额降至{min_cash:.1f}万，低于警戒线{critical_line}万",
             "actions": [
                 "立即催收大额应收账款",
                 "暂停非必要支出",
                 "准备短期融资安排",
             ]
         })
-    elif min_cash < DEFAULT_CASH_WARNING:
+    elif min_cash < warning_line:
         suggestions.append({
             "type": "warning",
-            "message": f"预计{min_date}现金余额降至{min_cash:.1f}万，低于关注线{DEFAULT_CASH_WARNING}万",
+            "message": f"预计{min_date}现金余额降至{min_cash:.1f}万，低于关注线{warning_line}万",
             "actions": [
                 "加快应收账款回款",
                 "控制采购付款节奏",
@@ -606,8 +624,8 @@ def forecast_cash_flow_with_plans(
     db: Session,
     days: int = 30,
     current_cash: Optional[float] = None,
-    warning_line: float = DEFAULT_CASH_WARNING,
-    critical_line: float = DEFAULT_CASH_CRITICAL,
+    warning_line: Optional[float] = None,
+    critical_line: Optional[float] = None,
     include_plans: bool = True,
 ) -> dict:
     """
@@ -616,11 +634,21 @@ def forecast_cash_flow_with_plans(
     2. 叠加 cash_plans 的应收(收) / 应付(付)
     3. 识别资金缺口日期（余额 < 警戒线）
     4. 生成缺口前3天预警点
+
+    阈值来源（G1，2026-10-17）：None → 本账套配置（alert_rules: cash_gap_threshold）
+    → 未配置时默认 20/10 万；显式传入值优先（复算对拍用）。响应内 `threshold_source`
+    明写本次取值来源，便于页面标注与回执取证。
     """
     from collections import defaultdict
     from app.models import CashPlan
 
-    base = forecast_cash_flow(entity_id, db, days, current_cash)
+    if warning_line is None or critical_line is None:
+        cfg_warning, cfg_critical = get_cash_gap_thresholds(db, entity_id)
+        warning_line = cfg_warning if warning_line is None else warning_line
+        critical_line = cfg_critical if critical_line is None else critical_line
+
+    base = forecast_cash_flow(entity_id, db, days, current_cash,
+                              warning_line=warning_line, critical_line=critical_line)
     base_cash = base["base_cash"]
 
     # 预算校准：本月经营现金流预算优先作为基线（万元/月）
@@ -805,6 +833,7 @@ def forecast_cash_flow_with_plans(
         "days": days,
         "warning_line": warning_line,
         "critical_line": critical_line,
+        "threshold_source": describe_cash_threshold_source(db, entity_id),
         "budget_monthly_ocf": budget_ocf,
         "forecast": forecast,
         "gap_dates": gap_dates,