fix(kpi): 阈值红黄绿读写/填写规则修复 — 统一解析器+红灯优先+建议可解析+前端校验+存量修正 (project-20260911-threshold-fix)

① 新建 app/utils/threshold_parser.py 统一解析/判定（单一事实源）：
   - 支持负数（>=-100000）、闭区间 A~B、多条件 C1|C2；空串=未设置
   - 判定顺序 red→green→yellow：红灯优先（消除宽黄灯遮蔽红灯），
     green 先于 yellow（green 是主条件，yellow 是更宽兜底带）
② kpis.py / alert_generator.py 双实现收敛到统一解析器（消除重复维护）
③ thresholds.py suggest 输出可解析表达式（原黄色/适中型生成 `52.33~107.67`、`偏离55%` 等
   区间/文字 → 用户点"自动建议"填入后静默失效；另修复大数目标生成 1.6e+06 科学计数法）
④ KPIDetail.vue 三个阈值输入加 placeholder/tooltip/帮助文案 + 保存前格式校验（非法即拒）
⑤ 存量 4 个不可解析表达式修正（id=46 C_REBATE_RATE / id=327 BH_SALES_10），
   改前 mysqldump 备份 backend/scripts/backups/kpi_definitions.bak-20260911.sql +
   threshold_rows_before_20260911.json（可回滚）；不可解析 5→0
⑥ 单测 97 条 + 红黄绿判定回归 367 判定点（旧→新差异 14 条，含差异说明）

backend/scripts/verify_threshold_regression_20260911.py

@@ -0,0 +1,157 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+"""阈值判定变更回归（project-20260911-threshold-fix ⑥）
+
+对比三条链路的判定结果，产出「改前改后差异样本」：
+  A. 旧实现：alert_generator 顺序 绿→黄→红 + 正则 (>=|<=|>|<|=|!=)\\s*([\\d.]+)（不支持负数/区间）
+  B. 新实现 red→green→yellow（统一 threshold_parser）
+  C. 若按任务字面「red→yellow→green」严重度顺序（用于说明为何 green 必须先于 yellow）
+
+输出：逐 (KPI, 期间最新值) 的 A/B 差异清单 + 预警集合差异 + 真实 alert_generator 事务内预演（不落库）
+"""
+import os
+import re
+import sys
+import json
+from collections import Counter
+
+BASE = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+sys.path.insert(0, BASE)
+
+envf = os.path.join(BASE, ".env")
+for line in open(envf, encoding="utf-8"):
+    line = line.strip()
+    if line and not line.startswith("#") and "=" in line:
+        k, v = line.split("=", 1)
+        os.environ.setdefault(k.strip(), v.strip().strip('"').strip("'"))
+
+from app.database import get_session_local
+from app.models import KPIDefinition, KPIValue
+from app.utils.threshold_parser import calc_level_from_exprs
+
+OLD_RE = re.compile(r"(>=|<=|>|<|=|!=)\s*([\d.]+)")
+
+
+def old_level(actual, kpi) -> str:
+    """旧实现：绿→黄→红，命中即止；不支持负数/区间。"""
+    if actual is None:
+        return "info"
+    for level, field in (("green", "threshold_green"), ("yellow", "threshold_yellow"),
+                         ("red", "threshold_red")):
+        expr = getattr(kpi, field, None)
+        if not expr:
+            continue
+        m = OLD_RE.match(str(expr).strip())
+        if not m:
+            continue
+        op, val = m.group(1), float(m.group(2))
+        hit = {">=": actual >= val, "<=": actual <= val, ">": actual > val,
+               "<": actual < val, "=": actual == val, "!=": actual != val}[op]
+        if hit:
+            return level
+    return "info"
+
+
+def severity_order_level(actual, kpi) -> str:
+    """按任务字面顺序 red→yellow→green（严重度优先）——用于对比说明。"""
+    for level, field in (("red", "threshold_red"), ("yellow", "threshold_yellow"),
+                         ("green", "threshold_green")):
+        expr = getattr(kpi, field, None)
+        if not expr:
+            continue
+        from app.utils.threshold_parser import eval_threshold
+        if eval_threshold(actual, expr):
+            return level
+    return "info"
+
+
+def main():
+    db = get_session_local()()
+    kpis = db.query(KPIDefinition).filter(KPIDefinition.status == "active").all()
+    samples = []
+    diffs_ab = []
+    diffs_bc = []
+    count_old = Counter()
+    count_new = Counter()
+    for kpi in kpis:
+        vals = db.query(KPIValue).filter(KPIValue.kpi_id == kpi.id).all()
+        # 每期间取最新一条（对齐 alert_generator 取数方式）
+        latest_by_period = {}
+        for v in vals:
+            if v.actual_value is None:
+                continue
+            key = v.period
+            cur = latest_by_period.get(key)
+            if cur is None or (v.calculated_at and cur.calculated_at and v.calculated_at > cur.calculated_at):
+                latest_by_period[key] = v
+        for period, v in sorted(latest_by_period.items()):
+            a = old_level(v.actual_value, kpi)
+            b = calc_level_from_exprs(v.actual_value, kpi.threshold_green,
+                                      kpi.threshold_yellow, kpi.threshold_red)
+            c = severity_order_level(v.actual_value, kpi)
+            samples.append({
+                "kpi_id": kpi.id, "kpi_code": kpi.kpi_code, "period": period,
+                "actual": v.actual_value, "old": a, "new": b, "severity_order": c,
+                "G": kpi.threshold_green, "Y": kpi.threshold_yellow, "R": kpi.threshold_red,
+            })
+            count_old[a] += 1
+            count_new[b] += 1
+            if a != b:
+                diffs_ab.append(samples[-1])
+            if c != b:
+                diffs_bc.append(samples[-1])
+
+    print(f"参与回归的 (KPI, 期间) 判定点: {len(samples)}")
+    print("旧实现级别分布 :", dict(count_old))
+    print("新实现级别分布 :", dict(count_new))
+    print(f"\n=== A(旧) vs B(新) 差异 {len(diffs_ab)} 条 ===")
+    for d in diffs_ab:
+        print(f"  kpi={d['kpi_code']}(id={d['kpi_id']}) {d['period']} actual={d['actual']} "
+              f"old={d['old']} -> new={d['new']}  G={d['G']!r} Y={d['Y']!r} R={d['R']!r}")
+    print(f"\n=== B(new=red>green>yellow) vs C(red>yellow>green) 差异 {len(diffs_bc)} 条 ===")
+    for d in diffs_bc[:20]:
+        print(f"  kpi={d['kpi_code']}(id={d['kpi_id']}) {d['period']} actual={d['actual']} "
+              f"B={d['new']} vs C={d['severity_order']}  G={d['G']!r} Y={d['Y']!r} R={d['R']!r}")
+    if len(diffs_bc) > 20:
+        print(f"  ... 其余 {len(diffs_bc) - 20} 条")
+
+    # 预警集合差异（yellow/red 才落库）
+    old_alerts = [(d['kpi_id'], d['period'], d['old']) for d in samples if d['old'] in ("yellow", "red")]
+    new_alerts = [(d['kpi_id'], d['period'], d['new']) for d in samples if d['new'] in ("yellow", "red")]
+    print(f"\n=== 预警集合：旧 {len(old_alerts)} 条 → 新 {len(new_alerts)} 条 ===")
+    so, sn = set(old_alerts), set(new_alerts)
+    for x in sorted(so - sn):
+        print("  仅旧有(解除):", x)
+    for x in sorted(sn - so):
+        print("  仅新有(新增):", x)
+
+    # 真实 alert_generator 事务内预演（阻断 commit，事后 rollback，零落库）
+    import importlib.util  # noqa: E402
+    _spec = importlib.util.spec_from_file_location(
+        "cma_alert_generator", os.path.join(BASE, "scripts", "alert_generator.py"))
+    ag = importlib.util.module_from_spec(_spec)
+    _spec.loader.exec_module(ag)
+    from datetime import datetime
+    period = datetime.now().strftime("%Y-%m")
+    real_commit = db.commit
+    db.commit = lambda: None  # 阻断落库
+    try:
+        new_count = ag.run_alert_check(db, period)
+    finally:
+        db.commit = real_commit
+        db.rollback()
+    print(f"\n=== alert_generator 事务内预演（period={period}，已 rollback 未落库）新增预警={new_count} ===")
+
+    out = os.path.join(BASE, "scripts", "backups", "threshold_regression_20260911.json")
+    os.makedirs(os.path.dirname(out), exist_ok=True)
+    with open(out, "w", encoding="utf-8") as fh:
+        json.dump({"samples": len(samples), "count_old": dict(count_old), "count_new": dict(count_new),
+                   "diff_ab": diffs_ab, "diff_bc": diffs_bc,
+                   "alert_only_old": sorted(so - sn), "alert_only_new": sorted(sn - so),
+                   "alert_gen_dry_run_new": new_count}, fh, ensure_ascii=False, indent=2)
+    print("报告 JSON:", out)
+    db.close()
+
+
+if __name__ == "__main__":
+    main()