diff --git a/B06_Section/B06_Section_UI_Cross_Culvert_Geom.ts b/B06_Section/B06_Section_UI_Cross_Culvert_Geom.ts
index 5bbd5364a..70e2cd2de 100644
--- a/B06_Section/B06_Section_UI_Cross_Culvert_Geom.ts
+++ b/B06_Section/B06_Section_UI_Cross_Culvert_Geom.ts
@@ -601,8 +601,11 @@ export function computeCulvertLayout(
   //    접점을 다시 깨뜨리지 않는다 — 종전 어긋남의 직접 원인이 이 순서였다.
   const slopeOf = (wall: WallLayout): FillSlopeSegment =>
     fillSlopeOf(wall, wall.role === "inlet" ? inletInfo.edge : outletInfo.edge);
+  // 유출 끝 연결선(139-4)이 있으면 벽 모서리 절토(91-4)를 또 잇지 않음 — 설계선이 접힘(186-1)
+  const outletTail = drawnFillPoints(extrasForArea, true).length > 0;
   for (const wall of walls) {
-    const slope = withBackCut(slopeOf(wall), wall, section.design, groundAt, !culvert.hidden_pipe);
+    const backCut = !culvert.hidden_pipe && !outletTail;
+    const slope = withBackCut(slopeOf(wall), wall, section.design, groundAt, backCut);
     // 사면선은 노견부터 우리가 그림 — 트림을 노견까지 당겨 백엔드 설계선 성토 구간을 통째로 덮음
     if (wall.outward > 0) {
       trimMax = slope.points[0].offset;
diff --git a/resources/tester/fixtures/b06_186_1_pipe_292.json b/resources/tester/fixtures/b06_186_1_pipe_292.json
new file mode 100644
index 000000000..6459b8908
--- /dev/null
+++ b/resources/tester/fixtures/b06_186_1_pipe_292.json
@@ -0,0 +1,917 @@
+{
+ "source": "검증_랩탑메인(226fc805) route 282 · No.14+12.22 관(파형강관 D800 · 유입 L형 집수정 · 유출 흙막이 돌쌓기(찰) H1.3) · 저장 design 그대로(유출 d 9.0)",
+ "cross_sections": [
+  {
+   "station_id": "station_000000292220",
+   "chainage_m": 292.22,
+   "label": "STA.0+292.220",
+   "kind": "irregular",
+   "center_x": 208535.186869,
+   "center_y": 367765.719131,
+   "center_z": 860.254154,
+   "azimuth_deg": 134.945611,
+   "plan_radius_m": null,
+   "curve_outer_side": "left",
+   "curve_widening_m": 2.033,
+   "uphill_side": "right",
+   "structure": "파형강관 D800",
+   "samples": [
+    {
+     "offset_m": -20.0,
+     "elevation_m": 875.942681,
+     "valid": true
+    },
+    {
+     "offset_m": -19.5,
+     "elevation_m": 875.563445,
+     "valid": true
+    },
+    {
+     "offset_m": -19.0,
+     "elevation_m": 875.223804,
+     "valid": true
+    },
+    {
+     "offset_m": -18.5,
+     "elevation_m": 874.839366,
+     "valid": true
+    },
+    {
+     "offset_m": -18.0,
+     "elevation_m": 874.373517,
+     "valid": true
+    },
+    {
+     "offset_m": -17.5,
+     "elevation_m": 873.834699,
+     "valid": true
+    },
+    {
+     "offset_m": -17.0,
+     "elevation_m": 873.328076,
+     "valid": true
+    },
+    {
+     "offset_m": -16.5,
+     "elevation_m": 873.003181,
+     "valid": true
+    },
+    {
+     "offset_m": -16.0,
+     "elevation_m": 872.868685,
+     "valid": true
+    },
+    {
+     "offset_m": -15.5,
+     "elevation_m": 872.700062,
+     "valid": true
+    },
+    {
+     "offset_m": -15.0,
+     "elevation_m": 872.492793,
+     "valid": true
+    },
+    {
+     "offset_m": -14.5,
+     "elevation_m": 872.264882,
+     "valid": true
+    },
+    {
+     "offset_m": -14.0,
+     "elevation_m": 871.921377,
+     "valid": true
+    },
+    {
+     "offset_m": -13.5,
+     "elevation_m": 871.449263,
+     "valid": true
+    },
+    {
+     "offset_m": -13.0,
+     "elevation_m": 871.050131,
+     "valid": true
+    },
+    {
+     "offset_m": -12.5,
+     "elevation_m": 870.664549,
+     "valid": true
+    },
+    {
+     "offset_m": -12.0,
+     "elevation_m": 870.348929,
+     "valid": true
+    },
+    {
+     "offset_m": -11.5,
+     "elevation_m": 869.897268,
+     "valid": true
+    },
+    {
+     "offset_m": -11.0,
+     "elevation_m": 869.481532,
+     "valid": true
+    },
+    {
+     "offset_m": -10.5,
+     "elevation_m": 869.031119,
+     "valid": true
+    },
+    {
+     "offset_m": -10.0,
+     "elevation_m": 868.558707,
+     "valid": true
+    },
+    {
+     "offset_m": -9.5,
+     "elevation_m": 868.123739,
+     "valid": true
+    },
+    {
+     "offset_m": -9.0,
+     "elevation_m": 867.798147,
+     "valid": true
+    },
+    {
+     "offset_m": -8.5,
+     "elevation_m": 867.489499,
+     "valid": true
+    },
+    {
+     "offset_m": -8.0,
+     "elevation_m": 867.256843,
+     "valid": true
+    },
+    {
+     "offset_m": -7.5,
+     "elevation_m": 867.081439,
+     "valid": true
+    },
+    {
+     "offset_m": -7.0,
+     "elevation_m": 866.940587,
+     "valid": true
+    },
+    {
+     "offset_m": -6.5,
+     "elevation_m": 866.550692,
+     "valid": true
+    },
+    {
+     "offset_m": -6.0,
+     "elevation_m": 865.812117,
+     "valid": true
+    },
+    {
+     "offset_m": -5.5,
+     "elevation_m": 864.812694,
+     "valid": true
+    },
+    {
+     "offset_m": -5.0,
+     "elevation_m": 864.211627,
+     "valid": true
+    },
+    {
+     "offset_m": -4.5,
+     "elevation_m": 863.993389,
+     "valid": true
+    },
+    {
+     "offset_m": -4.0,
+     "elevation_m": 863.791331,
+     "valid": true
+    },
+    {
+     "offset_m": -3.5,
+     "elevation_m": 863.6089,
+     "valid": true
+    },
+    {
+     "offset_m": -3.0,
+     "elevation_m": 863.47762,
+     "valid": true
+    },
+    {
+     "offset_m": -2.5,
+     "elevation_m": 863.178131,
+     "valid": true
+    },
+    {
+     "offset_m": -2.0,
+     "elevation_m": 862.70616,
+     "valid": true
+    },
+    {
+     "offset_m": -1.5,
+     "elevation_m": 862.084857,
+     "valid": true
+    },
+    {
+     "offset_m": -1.0,
+     "elevation_m": 861.397999,
+     "valid": true
+    },
+    {
+     "offset_m": -0.5,
+     "elevation_m": 860.781491,
+     "valid": true
+    },
+    {
+     "offset_m": 0.0,
+     "elevation_m": 860.254154,
+     "valid": true
+    },
+    {
+     "offset_m": 0.5,
+     "elevation_m": 860.008424,
+     "valid": true
+    },
+    {
+     "offset_m": 1.0,
+     "elevation_m": 859.743024,
+     "valid": true
+    },
+    {
+     "offset_m": 1.5,
+     "elevation_m": 859.431951,
+     "valid": true
+    },
+    {
+     "offset_m": 2.0,
+     "elevation_m": 859.169405,
+     "valid": true
+    },
+    {
+     "offset_m": 2.5,
+     "elevation_m": 858.865535,
+     "valid": true
+    },
+    {
+     "offset_m": 3.0,
+     "elevation_m": 858.524512,
+     "valid": true
+    },
+    {
+     "offset_m": 3.5,
+     "elevation_m": 858.164126,
+     "valid": true
+    },
+    {
+     "offset_m": 4.0,
+     "elevation_m": 857.818061,
+     "valid": true
+    },
+    {
+     "offset_m": 4.5,
+     "elevation_m": 857.442262,
+     "valid": true
+    },
+    {
+     "offset_m": 5.0,
+     "elevation_m": 857.021062,
+     "valid": true
+    },
+    {
+     "offset_m": 5.5,
+     "elevation_m": 856.664537,
+     "valid": true
+    },
+    {
+     "offset_m": 6.0,
+     "elevation_m": 856.388529,
+     "valid": true
+    },
+    {
+     "offset_m": 6.5,
+     "elevation_m": 856.164636,
+     "valid": true
+    },
+    {
+     "offset_m": 7.0,
+     "elevation_m": 855.840671,
+     "valid": true
+    },
+    {
+     "offset_m": 7.5,
+     "elevation_m": 855.415507,
+     "valid": true
+    },
+    {
+     "offset_m": 8.0,
+     "elevation_m": 855.15202,
+     "valid": true
+    },
+    {
+     "offset_m": 8.5,
+     "elevation_m": 854.88336,
+     "valid": true
+    },
+    {
+     "offset_m": 9.0,
+     "elevation_m": 854.52968,
+     "valid": true
+    },
+    {
+     "offset_m": 9.5,
+     "elevation_m": 854.210706,
+     "valid": true
+    },
+    {
+     "offset_m": 10.0,
+     "elevation_m": 853.936088,
+     "valid": true
+    },
+    {
+     "offset_m": 10.5,
+     "elevation_m": 853.667609,
+     "valid": true
+    },
+    {
+     "offset_m": 11.0,
+     "elevation_m": 853.315257,
+     "valid": true
+    },
+    {
+     "offset_m": 11.5,
+     "elevation_m": 852.962466,
+     "valid": true
+    },
+    {
+     "offset_m": 12.0,
+     "elevation_m": 852.592563,
+     "valid": true
+    },
+    {
+     "offset_m": 12.5,
+     "elevation_m": 852.365461,
+     "valid": true
+    },
+    {
+     "offset_m": 13.0,
+     "elevation_m": 852.241766,
+     "valid": true
+    },
+    {
+     "offset_m": 13.5,
+     "elevation_m": 852.168603,
+     "valid": true
+    },
+    {
+     "offset_m": 14.0,
+     "elevation_m": 852.137894,
+     "valid": true
+    },
+    {
+     "offset_m": 14.5,
+     "elevation_m": 852.122192,
+     "valid": true
+    },
+    {
+     "offset_m": 15.0,
+     "elevation_m": 852.082728,
+     "valid": true
+    },
+    {
+     "offset_m": 15.5,
+     "elevation_m": 851.581695,
+     "valid": true
+    },
+    {
+     "offset_m": 16.0,
+     "elevation_m": 850.702327,
+     "valid": true
+    },
+    {
+     "offset_m": 16.5,
+     "elevation_m": 849.751282,
+     "valid": true
+    },
+    {
+     "offset_m": 17.0,
+     "elevation_m": 849.271151,
+     "valid": true
+    },
+    {
+     "offset_m": 17.5,
+     "elevation_m": 849.023418,
+     "valid": true
+    },
+    {
+     "offset_m": 18.0,
+     "elevation_m": 848.775996,
+     "valid": true
+    },
+    {
+     "offset_m": 18.5,
+     "elevation_m": 848.584444,
+     "valid": true
+    },
+    {
+     "offset_m": 19.0,
+     "elevation_m": 848.552501,
+     "valid": true
+    },
+    {
+     "offset_m": 19.5,
+     "elevation_m": 848.524788,
+     "valid": true
+    },
+    {
+     "offset_m": 20.0,
+     "elevation_m": 848.338541,
+     "valid": true
+    }
+   ],
+   "culvert": {
+    "type": "pipe",
+    "pipe_kind": "파형강관",
+    "diameter_m": 0.8,
+    "min_cover_m": 0.5,
+    "foundation": null,
+    "inlet": {
+     "role": "inlet",
+     "structure": "집수정",
+     "basin_length_m": 2.0,
+     "basin_before_m": 1.0,
+     "basin_after_m": 1.0,
+     "basin_height_m": 1.3,
+     "basin_form": "L"
+    },
+    "outlet": {
+     "role": "outlet",
+     "structure": "기슭막이",
+     "revet_form": "돌쌓기(찰)",
+     "revet_height_m": 1.3,
+     "revet_length_m": 10.0,
+     "revet_before_m": 5.0,
+     "revet_after_m": 5.0,
+     "face_slope": 0.3
+    },
+    "chainage_m": 292.22
+   },
+   "design": {
+    "ground_type": "ripping_rock",
+    "geometry_preset": "rock",
+    "section_mode": "both_cut",
+    "ditch_side": "right",
+    "ditch_type": "standard",
+    "cut_slope_ratio": 0.4,
+    "soil_cut_slope_ratio": 1.0,
+    "two_stage_slope": true,
+    "fill_slope_ratio": 1.2,
+    "roadbed_width_m": 6.0,
+    "carriageway_width_m": 5.0,
+    "carriageway_standard_width_m": 3.0,
+    "widening_left_m": 2.0,
+    "widening_right_m": 0.0,
+    "cross_slope_pct": 3.0,
+    "ditch": {
+     "type": "standard",
+     "top_width_m": 0.9,
+     "bottom_width_m": 0.3,
+     "depth_m": 0.3
+    },
+    "ditch_enabled": true,
+    "ditch_choice": null,
+    "paved": false,
+    "road_edges": {
+     "left": {
+      "offset_m": 4.0,
+      "elevation_m": 857.4906
+     },
+     "right": {
+      "offset_m": -2.0,
+      "elevation_m": 857.3106
+     }
+    },
+    "carriageway_edges": {
+     "left": {
+      "offset_m": 3.5,
+      "elevation_m": 857.4756
+     },
+     "right": {
+      "offset_m": -1.5,
+      "elevation_m": 857.3256
+     }
+    },
+    "design_elevation_m": 857.3706,
+    "cut_area_m2": 27.9382,
+    "cut_soil_area_m2": 8.3598,
+    "cut_rock_area_m2": 19.5784,
+    "cut_rock_kind": "ripping_rock",
+    "fill_area_m2": 0.3364,
+    "spoil_fill_area_m2": 0.0,
+    "spoil_fill_side": null,
+    "spoil_fill_width_m": 0.0,
+    "spoil_fill_max_width_m": 0.0,
+    "spoil_fill_line": [],
+    "spoil_fill_unclosed": false,
+    "spoil_fill_replaced_fill_m2": 0.0,
+    "bench_cut_length_m": 0.0,
+    "slope_unclosed": false,
+    "fill_ground_slope": null,
+    "ditch_area_m2": 0.18,
+    "ditch_soil_area_m2": 0.0,
+    "ditch_rock_area_m2": 0.18,
+    "ditch_split_basis": "rock_boundary",
+    "design_line": [
+     {
+      "offset_m": -20.0,
+      "elevation_m": 875.9427
+     },
+     {
+      "offset_m": -19.5,
+      "elevation_m": 875.5634
+     },
+     {
+      "offset_m": -19.0,
+      "elevation_m": 875.2238
+     },
+     {
+      "offset_m": -18.5,
+      "elevation_m": 874.8394
+     },
+     {
+      "offset_m": -18.0,
+      "elevation_m": 874.3735
+     },
+     {
+      "offset_m": -17.5,
+      "elevation_m": 873.8347
+     },
+     {
+      "offset_m": -17.0,
+      "elevation_m": 873.3281
+     },
+     {
+      "offset_m": -16.5,
+      "elevation_m": 873.0032
+     },
+     {
+      "offset_m": -16.0,
+      "elevation_m": 872.8687
+     },
+     {
+      "offset_m": -15.5,
+      "elevation_m": 872.7001
+     },
+     {
+      "offset_m": -15.0,
+      "elevation_m": 872.4928
+     },
+     {
+      "offset_m": -14.5,
+      "elevation_m": 872.2649
+     },
+     {
+      "offset_m": -14.0,
+      "elevation_m": 871.9214
+     },
+     {
+      "offset_m": -13.5,
+      "elevation_m": 871.4493
+     },
+     {
+      "offset_m": -13.0,
+      "elevation_m": 871.0501
+     },
+     {
+      "offset_m": -12.5,
+      "elevation_m": 870.6645
+     },
+     {
+      "offset_m": -12.0,
+      "elevation_m": 870.3489
+     },
+     {
+      "offset_m": -11.5,
+      "elevation_m": 869.8973
+     },
+     {
+      "offset_m": -11.0,
+      "elevation_m": 869.4815
+     },
+     {
+      "offset_m": -10.5,
+      "elevation_m": 869.0311
+     },
+     {
+      "offset_m": -10.0,
+      "elevation_m": 868.5587
+     },
+     {
+      "offset_m": -9.5,
+      "elevation_m": 868.1237
+     },
+     {
+      "offset_m": -9.0,
+      "elevation_m": 867.7981
+     },
+     {
+      "offset_m": -8.5,
+      "elevation_m": 867.4895
+     },
+     {
+      "offset_m": -8.0,
+      "elevation_m": 867.2568
+     },
+     {
+      "offset_m": -7.75,
+      "elevation_m": 867.1691
+     },
+     {
+      "offset_m": -7.5,
+      "elevation_m": 866.9294
+     },
+     {
+      "offset_m": -7.0,
+      "elevation_m": 866.4294
+     },
+     {
+      "offset_m": -6.5,
+      "elevation_m": 865.9294
+     },
+     {
+      "offset_m": -6.2459,
+      "elevation_m": 865.6753
+     },
+     {
+      "offset_m": -6.0,
+      "elevation_m": 865.0606
+     },
+     {
+      "offset_m": -5.5,
+      "elevation_m": 863.8106
+     },
+     {
+      "offset_m": -5.0,
+      "elevation_m": 862.5606
+     },
+     {
+      "offset_m": -4.5,
+      "elevation_m": 861.3106
+     },
+     {
+      "offset_m": -4.0,
+      "elevation_m": 860.0606
+     },
+     {
+      "offset_m": -3.5,
+      "elevation_m": 858.8106
+     },
+     {
+      "offset_m": -3.0,
+      "elevation_m": 857.5606
+     },
+     {
+      "offset_m": -2.9,
+      "elevation_m": 857.3106
+     },
+     {
+      "offset_m": -2.6,
+      "elevation_m": 857.0106
+     },
+     {
+      "offset_m": -2.5,
+      "elevation_m": 857.0106
+     },
+     {
+      "offset_m": -2.3,
+      "elevation_m": 857.0106
+     },
+     {
+      "offset_m": -2.0,
+      "elevation_m": 857.3106
+     },
+     {
+      "offset_m": -1.5,
+      "elevation_m": 857.3256
+     },
+     {
+      "offset_m": -1.0,
+      "elevation_m": 857.3406
+     },
+     {
+      "offset_m": -0.5,
+      "elevation_m": 857.3556
+     },
+     {
+      "offset_m": 0.0,
+      "elevation_m": 857.3706
+     },
+     {
+      "offset_m": 0.5,
+      "elevation_m": 857.3856
+     },
+     {
+      "offset_m": 1.0,
+      "elevation_m": 857.4006
+     },
+     {
+      "offset_m": 1.5,
+      "elevation_m": 857.4156
+     },
+     {
+      "offset_m": 2.0,
+      "elevation_m": 857.4306
+     },
+     {
+      "offset_m": 2.5,
+      "elevation_m": 857.4456
+     },
+     {
+      "offset_m": 3.0,
+      "elevation_m": 857.4606
+     },
+     {
+      "offset_m": 3.5,
+      "elevation_m": 857.4756
+     },
+     {
+      "offset_m": 4.0,
+      "elevation_m": 857.4906
+     },
+     {
+      "offset_m": 4.2,
+      "elevation_m": 857.6677
+     },
+     {
+      "offset_m": 4.5,
+      "elevation_m": 857.4423
+     },
+     {
+      "offset_m": 5.0,
+      "elevation_m": 857.0211
+     },
+     {
+      "offset_m": 5.5,
+      "elevation_m": 856.6645
+     },
+     {
+      "offset_m": 6.0,
+      "elevation_m": 856.3885
+     },
+     {
+      "offset_m": 6.5,
+      "elevation_m": 856.1646
+     },
+     {
+      "offset_m": 7.0,
+      "elevation_m": 855.8407
+     },
+     {
+      "offset_m": 7.5,
+      "elevation_m": 855.4155
+     },
+     {
+      "offset_m": 8.0,
+      "elevation_m": 855.152
+     },
+     {
+      "offset_m": 8.5,
+      "elevation_m": 854.8834
+     },
+     {
+      "offset_m": 9.0,
+      "elevation_m": 854.5297
+     },
+     {
+      "offset_m": 9.5,
+      "elevation_m": 854.2107
+     },
+     {
+      "offset_m": 10.0,
+      "elevation_m": 853.9361
+     },
+     {
+      "offset_m": 10.5,
+      "elevation_m": 853.6676
+     },
+     {
+      "offset_m": 11.0,
+      "elevation_m": 853.3153
+     },
+     {
+      "offset_m": 11.5,
+      "elevation_m": 852.9625
+     },
+     {
+      "offset_m": 12.0,
+      "elevation_m": 852.5926
+     },
+     {
+      "offset_m": 12.5,
+      "elevation_m": 852.3655
+     },
+     {
+      "offset_m": 13.0,
+      "elevation_m": 852.2418
+     },
+     {
+      "offset_m": 13.5,
+      "elevation_m": 852.1686
+     },
+     {
+      "offset_m": 14.0,
+      "elevation_m": 852.1379
+     },
+     {
+      "offset_m": 14.5,
+      "elevation_m": 852.1222
+     },
+     {
+      "offset_m": 15.0,
+      "elevation_m": 852.0827
+     },
+     {
+      "offset_m": 15.5,
+      "elevation_m": 851.5817
+     },
+     {
+      "offset_m": 16.0,
+      "elevation_m": 850.7023
+     },
+     {
+      "offset_m": 16.5,
+      "elevation_m": 849.7513
+     },
+     {
+      "offset_m": 17.0,
+      "elevation_m": 849.2712
+     },
+     {
+      "offset_m": 17.5,
+      "elevation_m": 849.0234
+     },
+     {
+      "offset_m": 18.0,
+      "elevation_m": 848.776
+     },
+     {
+      "offset_m": 18.5,
+      "elevation_m": 848.5844
+     },
+     {
+      "offset_m": 19.0,
+      "elevation_m": 848.5525
+     },
+     {
+      "offset_m": 19.5,
+      "elevation_m": 848.5248
+     },
+     {
+      "offset_m": 20.0,
+      "elevation_m": 848.3385
+     }
+    ],
+    "cut_slope_segments": [
+     {
+      "side": "left",
+      "ratio": 1.0,
+      "rise_m": 0.2,
+      "run_m": 0.2,
+      "start_offset_m": 4.0,
+      "end_offset_m": 4.2,
+      "material": "soil"
+     },
+     {
+      "side": "right",
+      "ratio": 0.4,
+      "rise_m": 8.3647,
+      "run_m": 3.3459,
+      "start_offset_m": -2.9,
+      "end_offset_m": -6.2459,
+      "material": "rock"
+     },
+     {
+      "side": "right",
+      "ratio": 1.0,
+      "rise_m": 1.5041,
+      "run_m": 1.5041,
+      "start_offset_m": -6.2459,
+      "end_offset_m": -7.75,
+      "material": "soil"
+     }
+    ],
+    "rock_boundary_offset_m": -0.5,
+    "status": "provisional",
+    "pavement_suggested": false,
+    "revet_adjust": {
+     "outlet": {
+      "x": 0.0,
+      "d": 9.0,
+      "h": null,
+      "m": null
+     }
+    },
+    "pipe_length_m": 18.0,
+    "pipe_slope_pct": 42.0261,
+    "extra_walls": [],
+    "wall_fill_overlap": {
+     "outlet": 0
+    },
+    "inlet_basin": "L"
+   }
+  }
+ ]
+}
\ No newline at end of file
diff --git a/resources/tester/helper_186_1_outlet_fold.cjs b/resources/tester/helper_186_1_outlet_fold.cjs
new file mode 100644
index 000000000..14d84df96
--- /dev/null
+++ b/resources/tester/helper_186_1_outlet_fold.cjs
@@ -0,0 +1,116 @@
+/* 186-1 묻힌 관 유출 벽 설계선 접힘 헬퍼 — 화면 TS 를 그 자리에서 트랜스파일해 Node 로 돌림.
+ * 입력 = 검증_랩탑메인 No.14+12.22 사본(`fixtures/b06_186_1_pipe_292.json`) · 73-4 픽스처 관 340(절토 쪽 유출).
+ * 결과 = 표준출력 JSON 한 벌. 짝 = `test_186_1_outlet_fold.py`.
+ */
+const fs = require("fs");
+const path = require("path");
+const ts = require(path.join(__dirname, "..", "..", "config", "node_modules", "typescript"));
+
+const ROOT = path.join(__dirname, "..", "..");
+const cache = new Map();
+// 화면 전용 모듈(토스트) — 기하 계산엔 안 쓰임
+const STUBS = {
+  "@ui/ui_template_toast": { showToast: () => undefined },
+};
+
+function loadTs(file) {
+  const full = path.resolve(file);
+  if (cache.has(full)) return cache.get(full);
+  if (full.endsWith(".json")) {
+    const data = JSON.parse(fs.readFileSync(full, "utf8"));
+    cache.set(full, data);
+    return data;
+  }
+  const js = ts.transpileModule(fs.readFileSync(full, "utf8"), {
+    compilerOptions: {
+      module: ts.ModuleKind.CommonJS,
+      target: ts.ScriptTarget.ES2020,
+      esModuleInterop: true,
+    },
+  }).outputText;
+  const box = { exports: {} };
+  cache.set(full, box.exports);
+  const localRequire = (request) => {
+    if (STUBS[request]) return STUBS[request];
+    const alias = { "@util/": "common_util", "@ui/": "ui_template", "@config/": "config" };
+    for (const [prefix, dir] of Object.entries(alias))
+      if (request.startsWith(prefix))
+        return loadTs(resolve(path.join(ROOT, dir, request.slice(prefix.length))));
+    return loadTs(resolve(path.join(path.dirname(full), request)));
+  };
+  new Function("exports", "module", "require", js)(box.exports, box, localRequire);
+  cache.set(full, box.exports);
+  return box.exports;
+}
+const resolve = (base) =>
+  [base, `${base}.ts`, path.join(base, "index.ts")].find(
+    (p) => fs.existsSync(p) && fs.statSync(p).isFile(),
+  ) ?? `${base}.ts`;
+
+const B06 = (f) => path.join(ROOT, "B06_Section", f);
+const { computeStoredLayouts, structureAreaRows } = loadTs(B06("B06_Section_Structure_Layouts.ts"));
+const { computeCulvertLayout } = loadTs(B06("B06_Section_UI_Cross_Culvert_Geom.ts"));
+const read = (name) =>
+  JSON.parse(fs.readFileSync(path.join(__dirname, "fixtures", name), "utf8")).cross_sections;
+const clone = (v) => JSON.parse(JSON.stringify(v));
+const r2 = (v) => Math.round(v * 100) / 100;
+
+/** 유출 쪽 설계선(트림 사면) 점열 · 유출 벽 · 면적 행. */
+function study(sections, target) {
+  const section = sections.find((s) => Math.abs(s.chainage_m - target) < 0.01);
+  const { culvert } = computeStoredLayouts(section, sections);
+  const wall = culvert.walls.find((w) => w.role === "outlet");
+  const trim = culvert.designTrim;
+  const slope = (wall.outward > 0 ? trim.maxSlope : trim.minSlope).points;
+  const row = structureAreaRows(sections).find((r) => Math.abs(r.chainage_m - target) < 0.01);
+  return {
+    outward: wall.outward,
+    wallTop: r2(wall.topJoint.elevation),
+    groundAtWall: r2(groundOf(section, wall.topJoint.offset)),
+    offsets: slope.map((p) => r2(p.offset)),
+    elevations: slope.map((p) => r2(p.elevation)),
+    cut: row ? row.cut_area_m2 : null,
+    fill: row ? row.fill_area_m2 : null,
+  };
+}
+function groundOf(section, offset) {
+  const s = section.samples;
+  for (let i = 1; i < s.length; i += 1)
+    if (s[i].offset_m >= offset) {
+      const t = (offset - s[i - 1].offset_m) / (s[i].offset_m - s[i - 1].offset_m);
+      return s[i - 1].elevation_m + (s[i].elevation_m - s[i - 1].elevation_m) * t;
+    }
+  return NaN;
+}
+
+const out = {};
+// ① 저장값 그대로(유출 d 9.0) · ② 자동 자리(조작값 없음)
+const stored = read("b06_186_1_pipe_292.json");
+out.stored = study(stored, 292.22);
+const auto = clone(stored);
+auto[0].design.revet_adjust = null;
+out.auto = study(auto, 292.22);
+// ③ 91-4 절토 쪽 배관 유출(73-4 픽스처 관 340 · 유출 = 우측 절토)
+const base = read("b06_73_4_body_guard_sections.json");
+const s340 = clone(base.find((s) => Math.abs(s.chainage_m - 340) < 0.6));
+s340.uphill_side = "left";
+s340.culvert = {
+  type: "pipe",
+  chainage_m: 340,
+  pipe_kind: "흄관",
+  diameter_m: 1.0,
+  min_cover_m: 0.5,
+  inlet: { role: "inlet", structure: "기슭막이", revet_form: "돌쌓기(찰)" },
+  outlet: { role: "outlet", structure: "기슭막이", revet_form: "돌쌓기(찰)" },
+};
+s340.design.inlet_structure = "revet";
+const layout = computeCulvertLayout(s340, s340.samples, undefined, "revet");
+const wall340 = layout.walls.find((w) => w.role === "outlet");
+const slope340 = (wall340.outward > 0 ? layout.designTrim.maxSlope : layout.designTrim.minSlope)
+  .points;
+out.cut340 = {
+  outward: wall340.outward,
+  offsets: slope340.map((p) => r2(p.offset)),
+  elevations: slope340.map((p) => r2(p.elevation)),
+};
+process.stdout.write(JSON.stringify(out));
diff --git a/resources/tester/helper_91_ground_free.cjs b/resources/tester/helper_91_ground_free.cjs
index 5cb2a0ec8..4b34502db 100644
--- a/resources/tester/helper_91_ground_free.cjs
+++ b/resources/tester/helper_91_ground_free.cjs
@@ -185,9 +185,10 @@ function cutOutlet(edit = () => undefined) {
   s.design.inlet_structure = "revet";
   edit(s);
   const layout = computeCulvertLayout(s, s.samples, undefined, "revet");
-  const wall = layout.walls.find((w) => w.role === "outlet");
+  // 벽 뒤 절토 = 유출 끝 연결선(139-4) — 벽 모서리 절토는 또 잇지 않음(186-1)
+  const start = layout.outletFill.segments.at(-1).points[0];
   const pts = layout.designTrim.minSlope.points;
-  const from = pts.findIndex((p) => Math.abs(p.offset - wall.points[2].offset) < 1e-9);
+  const from = pts.findIndex((p) => Math.abs(p.offset - start.offset) < 1e-9);
   return profile(pts.slice(from), s.samples);
 }
 out.cutOutlet = cutOutlet();
diff --git a/resources/tester/test_186_1_outlet_fold.py b/resources/tester/test_186_1_outlet_fold.py
new file mode 100644
index 000000000..c477551ca
--- /dev/null
+++ b/resources/tester/test_186_1_outlet_fold.py
@@ -0,0 +1,73 @@
+"""PLAN 186-1 — 흙막이류 횡단 형상(랩탑 메인 프로젝트 No.14+12) 사본 재현.
+
+자료: 검증_랩탑메인(226fc805) No.14+12.22 = 관(파형강관 D800) · 유입 L형 집수정 · 유출 흙막이
+(돌쌓기(찰) H1.3) · 유출 쪽 원지반이 노견보다 높아 벽이 묻힘(벽 윗면 849.99 · 원지반 852.24).
+
+흠: 묻힌 유출 벽에 절토선이 둘 — 벽 바깥 윗모서리 절토(91-4 `withBackCut`)와 관 끝 3도 절토선
+(139-4). 둘 다 설계선(트림 사면)에 이어 붙어 선이 원지반까지 올랐다가 벽 앞으로 되내려 접힘
+(오프셋 13.45 → 14.59 → 13.69) → 카드 · B07 · 3D 모양이 꺾이고 서버 면적도 접힌 폐회로로 셈.
+
+고침: 유출 끝 연결선(139-4)이 있으면 벽 모서리 절토를 잇지 않음(`_Culvert_Geom.ts`).
+"""
+
+from __future__ import annotations
+
+import json
+import os
+import subprocess
+
+import pytest
+
+HERE = os.path.dirname(__file__)
+ROOT = os.path.join(HERE, "..", "..")
+
+pytestmark = pytest.mark.skipif(
+    not os.path.isdir(os.path.join(ROOT, "config", "node_modules")),
+    reason="프론트엔드 의존성 미설치",
+)
+
+
+@pytest.fixture(scope="module")
+def out() -> dict:
+    proc = subprocess.run(  # noqa: S603 — 고정 실행 파일
+        ["node", os.path.join(HERE, "helper_186_1_outlet_fold.cjs")],
+        capture_output=True,
+        text=True,
+        encoding="utf-8",
+        timeout=60,
+    )
+    assert proc.returncode == 0, proc.stderr
+    return json.loads(proc.stdout)
+
+
+def _one_way(offsets: list[float], outward: int) -> bool:
+    """설계선이 바깥으로만 나아감 — 되돌아가면 접힌 것."""
+    return all((b - a) * outward >= -1e-9 for a, b in zip(offsets, offsets[1:]))
+
+
+def _no_peak(elevations: list[float]) -> bool:
+    """원지반까지 올랐다 되내리는 뾰족 봉우리 없음."""
+    return not any(b > a and b > c for a, b, c in zip(elevations, elevations[1:], elevations[2:]))
+
+
+@pytest.mark.parametrize("case", ["stored", "auto"])
+def test_묻힌_유출_벽_설계선이_안_접힘(out: dict, case: str) -> None:
+    """저장값(d 9.0)도 자동 자리도 — 벽은 묻혀 있고 설계선은 한 방향."""
+    study = out[case]
+    assert study["wallTop"] < study["groundAtWall"]  # 사본이 묻힌 벽을 재현
+    assert _one_way(study["offsets"], study["outward"]), study["offsets"]
+    assert _no_peak(study["elevations"]), study["elevations"]
+
+
+def test_저장값_사본_면적(out: dict) -> None:
+    """접힌 폐회로(절토 27.94 · 성토 0.34 ㎡) → 노견~벽~3도 선 절토만."""
+    assert out["stored"]["cut"] == pytest.approx(34.0391, abs=1e-3)
+    assert out["stored"]["fill"] == 0
+    assert out["auto"]["cut"] == pytest.approx(16.8211, abs=1e-3)
+
+
+def test_절토_쪽_배관_유출도_안_접힘(out: dict) -> None:
+    """91-4 자료(관 340 · 유출 = 절토 쪽) — 3도 선이 못 만나 복합경사 하나로 원지반까지."""
+    study = out["cut340"]
+    assert _one_way(study["offsets"], study["outward"]), study["offsets"]
+    assert _no_peak(study["elevations"]), study["elevations"]