feat: 添加线索引擎、NLQ、场景检测、前端界面等核心功能模块

backend/tests/test_scenarios.py

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+"""场景检测器单元测试（纯逻辑，无需数据库）。"""
+
+from app.scenarios.churn_fraud import (
+    CohortPoint,
+    churn_risk_score,
+    commission_quality_mismatch,
+    detect_pulse_decay,
+)
+from app.scenarios.split_contract import (
+    ContractRecord,
+    detect_threshold_edge,
+    split_risk_score,
+)
+
+# ---------- 场景一：政企拆单 (R8) ----------
+
+def test_threshold_edge_detects_split():
+    # 阈值 100 万，8 份合同集中在 79万-99万
+    contracts = [ContractRecord(f"C{i}", f"CUST{i}", 810000 + i * 20000) for i in range(8)]
+    finding = detect_threshold_edge(contracts, approval_threshold=1_000_000)
+    assert finding.hit
+    assert len(finding.near_threshold) == 8
+
+
+def test_threshold_edge_no_split_when_amounts_spread():
+    contracts = [
+        ContractRecord("C1", "A", 100000),
+        ContractRecord("C2", "B", 2_000_000),
+    ]
+    finding = detect_threshold_edge(contracts, approval_threshold=1_000_000)
+    assert not finding.hit
+
+
+def test_split_score_higher_with_shared_controller():
+    contracts = [ContractRecord(f"C{i}", f"CUST{i}", 850000) for i in range(8)]
+    finding = detect_threshold_edge(contracts, 1_000_000)
+    s_no = split_risk_score(finding, shared_controller=False)
+    s_yes = split_risk_score(finding, shared_controller=True)
+    assert s_yes > s_no
+    assert s_yes <= 1.0
+
+
+def test_threshold_must_be_positive():
+    import pytest
+
+    with pytest.raises(ValueError):
+        detect_threshold_edge([], approval_threshold=0)
+
+
+# ---------- 场景二：养卡骗补 (R9) ----------
+
+def test_pulse_decay_detects_cliff():
+    curve = [
+        CohortPoint(0, 1.0),
+        CohortPoint(1, 0.95),
+        CohortPoint(2, 0.92),
+        CohortPoint(3, 0.10),  # 第3个月断崖
+    ]
+    finding = detect_pulse_decay(curve)
+    assert finding.pulse_then_decay
+    assert finding.cliff_month == 3
+
+
+def test_no_cliff_for_smooth_curve():
+    curve = [CohortPoint(i, 1.0 - 0.05 * i) for i in range(5)]
+    finding = detect_pulse_decay(curve)
+    assert not finding.pulse_then_decay
+
+
+def test_commission_mismatch_high_for_zero_usage():
+    m = commission_quality_mismatch(commission_paid=100000, active_ratio=0.05, zero_usage_ratio=0.9)
+    assert m > 0.7
+
+
+def test_churn_score_combines_signals():
+    curve = [CohortPoint(0, 1.0), CohortPoint(1, 0.2)]
+    finding = detect_pulse_decay(curve)
+    score = churn_risk_score(finding, mismatch=0.8)
+    assert 0.0 < score <= 1.0