2

tests/test_planner.py

@@ -9,7 +9,8 @@ from mcm26b.belief import CandidateRegion
 from mcm26b.config import ProblemConfig
 from mcm26b.geometry.localization import Measurement
 from mcm26b.geometry.planning import first_bearing_candidate_disk
-from mcm26b.planner import (bearing_deg, clear_certificate, select_measurement_point,
+from mcm26b.planner import (_worst_posterior_radius, bearing_deg,
+                            clear_certificate, select_measurement_point,
                             select_second_point)
 from mcm26b.protocol.client import SimulatorClient
 from mcm26b.sim import LocalSimTransport, LocalSimulator
@@ -71,6 +72,24 @@ class SelectionGuaranteeTests(TestCase):
                 self.assertTrue(probe.polygon and probe.contains(g, tol_m=0.05),
                                 f"后验剪掉了生成读数的边界点 {g}")
 
+    def test_posterior_scores_near_branch(self):
+        """后验评分必须包含 near 分支，否则低报最坏后验半径。
+
+        候选集为线段 [-4,4]×{0}、测点为原点时，任意合法读数必为 near
+        （源距原点 <=4 < 5m），后验仍为整段线段（半径 4m）；只枚举
+        direction 端点会错误报出 2m。
+        """
+        region = CandidateRegion([(-4.0, 0.0), (4.0, 0.0)])
+        half = 1.005
+        witnesses = region.witnesses(60.0)
+        self.assertEqual(witnesses, [(-4.0, 0.0), (4.0, 0.0)])
+        worst = _worst_posterior_radius(region, (0.0, 0.0), witnesses, half,
+                                        CONFIG.field.near_radius_m,
+                                        CONFIG.search.polygon_sides)
+        self.assertGreaterEqual(worst, 4.0 - 1e-6,
+                                "near 分支后验半径应逼近候选集半径 4m")
+        self.assertLessEqual(worst, 4.0 + region.slack_m + 0.1)
+
     def test_move_cost_recorded_and_reason_explains(self):
         region = _k1_region()
         plan = select_measurement_point(region, (500.0, 500.0), CONFIG)