diff --git a/A00_Common/design/logic/design_calc_node.ts b/A00_Common/design/logic/design_calc_node.ts
index 71e2cf0b6..546ab2ac5 100644
--- a/A00_Common/design/logic/design_calc_node.ts
+++ b/A00_Common/design/logic/design_calc_node.ts
@@ -16,6 +16,7 @@
  *          chainage_m? }] · facilities?: { pipes · structures }(시설 구간 · 511-B B-4) } ·
  *          berm?: { structures: 구조물 정본 목록 · chainages: [측점 m] } ·
  *          rebase? · carry?(노선 바뀐 [저장] · `design_calc_node_carry.ts`) ·
+ *          definition? · attach? · cross_enforce?(형상 얹기 · [저장] 횡단 · `design_calc_node_cross.ts` · 511-B B-4) ·
  *          stages?(묶음 단계 · `design_calc_node_stages.ts` · 511-B) } }
  *   출력  { results: { [id]: 값 }, available: [id…] }
  *         — 차례는 요청 차례가 아니라 기댐 차례(누가토량 앞에 구조물 면적을 상세에 얹음 ·
@@ -49,13 +50,14 @@ import {
   structureAreaRows,
 } from "../../../B06_Section/B06_Section_Structure_Layouts";
 import { carryRunners, type CarryInputs } from "./design_calc_node_carry";
+import { crossRunners, useDefinition, type CrossInputs } from "./design_calc_node_cross";
 import { followRunners, type FollowInputs } from "./design_calc_node_follow";
 import { STAGE_IDS, stageRunners, type StagesInputs } from "./design_calc_node_stages";
 import { TRIAL_IDS, trialRunners, type TrialInputs } from "./design_calc_node_trial";
 
 type HaulOptions = NonNullable<Parameters<typeof computeHaulPlan>[2]>;
 
-interface CalcInputs extends FollowInputs, CarryInputs, TrialInputs, StagesInputs {
+interface CalcInputs extends FollowInputs, CarryInputs, CrossInputs, TrialInputs, StagesInputs {
   detail?: SectionDetailResponse;
   route_points?: RoutePoint[];
   context?: Partial<
@@ -94,7 +96,7 @@ interface CalcInputs extends FollowInputs, CarryInputs, TrialInputs, StagesInput
       chainage_m?: number;
     }>;
     /** 관 지점 · 구조물 정본 → 측점마다 포장 · 기울임 · 세월교 하강(`facilityRanges` · C3) */
-    facilities?: { pipes: CulvertPipePoint[]; structures: FacilityStructure[] };
+    facilities?: { pipes: CulvertPipePoint[]; structures: FacilityStructure[] | null };
   };
 }
 
@@ -110,6 +112,7 @@ async function runDesignCalc(run: readonly string[], inputs: CalcInputs) {
     ...carryRunners(inputs), // 노선 바뀐 [저장] 다시 얹기 — 관 · 구조물 초안 · 횡단 고침(472-6 6-B)
     ...trialRunners(inputs), // 계산 자리 「서버」 시험 길(511-A)
     ...stageRunners(inputs), // 묶음 단계 노선 ~ 횡단(511-B B-1)
+    ...crossRunners(inputs), // 형상 얹기 · [저장] 횡단 한 바퀴(511-B B-4)
     // 구조물 측점 면적 · 관 길이를 상세에 얹음(자리에서) — 뒤 누가토량이 고친 면적 위에서 쌓임.
     "structure.layouts": () => {
       const areas = structureAreaRows(sections);
@@ -167,8 +170,9 @@ async function runDesignCalc(run: readonly string[], inputs: CalcInputs) {
     // 측점마다 TS 짝(`computeCrossDesign`) — 못 세우면 그 자리 { error }(파이썬은 ValueError 로 되던짐).
     "cross.design": () => {
       const batch = inputs.cross_design;
+      if (batch?.facilities) useDefinition(inputs.definition);
       const ranges = batch?.facilities
-        ? facilityRanges(batch.facilities.pipes, batch.facilities.structures)
+        ? facilityRanges(batch.facilities.pipes, batch.facilities.structures ?? [])
         : null;
       return (batch?.stations ?? []).map((station) => {
         try {
diff --git a/A00_Common/design/logic/design_calc_node_cross.ts b/A00_Common/design/logic/design_calc_node_cross.ts
new file mode 100644
index 000000000..aebfa22e1
--- /dev/null
+++ b/A00_Common/design/logic/design_calc_node_cross.ts
@@ -0,0 +1,72 @@
+/* =============================================================================
+ * A00_Common/design/logic/design_calc_node_cross.ts
+ * 계산 Node 입구(`design_calc_node.ts`)의 횡단 몫(PLAN 511-B B-4) — 서버 GET · [저장] 이 부르는 횡단 셈을
+ * 브라우저와 같은 TS 로(파이썬 짝을 걷는 자리).
+ *
+ *   facility.attach  측점 그림 자료(관 세트 · 벽 · 포장 · 맹암거 · 빈칸 경고 · `attachShapes` · F4 F5 F6 C6)
+ *     입력 attach { sections: [{ chainage_m · center_x · center_y }] · pipes · structures · types }
+ *     출력 { shapes: 측점마다 그림 자료 칸만 · misses: { outside · far } }
+ *   cross.enforce    [저장] 횡단 한 바퀴(`enforceSavedCross` · 설계선 → 미교차 넓힘 → 포장 → 세월교 하강 · G2 C3)
+ *     입력 cross_enforce = `SaveCrossInput` + grid(DTM 격자 이진 경로 · 넓힘 때만 읽음)
+ *     출력 측점마다 { design · samples?(넓힘) · extended? } | null
+ * 구조물 표 = 서버 정의(`definition` · M02 반영) — 받으면 갈아 끼움(파이썬 `catalog_row` 와 같은 표).
+ * ========================================================================== */
+
+import { attachShapes, SHAPE_KEYS, type AttachType } from "@util/common_util_structure_attach";
+import { useCatalogDefinition, type CatalogDefinition } from "@util/common_util_structure_catalog";
+import type { PlanPipe, PlanStructure } from "@util/common_util_structure_station";
+import {
+  enforceSavedCross,
+  type SaveCrossInput,
+} from "../../../B06_Section/logic/B06_Section_Cross_Save";
+import { gridAt } from "./design_calc_node_stages";
+
+export interface CrossInputs {
+  definition?: CatalogDefinition | null;
+  attach?: {
+    sections: Array<{ chainage_m: number; center_x?: number | null; center_y?: number | null }>;
+    pipes: PlanPipe[];
+    structures: PlanStructure[];
+    types: AttachType[];
+  };
+  cross_enforce?: SaveCrossInput & { grid?: string | null };
+}
+
+let defined = "";
+
+/** 서버 정의로 구조물 표를 갈아 끼움 — 같은 정의면 그대로(늘 떠 있는 Node). */
+export function useDefinition(definition: CatalogDefinition | null | undefined): void {
+  if (!definition) return;
+  const key = JSON.stringify(definition);
+  if (key === defined) return;
+  useCatalogDefinition(definition);
+  defined = key;
+}
+
+const SHAPE_FIELDS = [...SHAPE_KEYS, "blank"];
+
+export function crossRunners(inputs: CrossInputs): Record<string, () => unknown> {
+  return {
+    "facility.attach": () => {
+      useDefinition(inputs.definition);
+      const attach = inputs.attach;
+      if (!attach) throw new Error("형상 얹기 입력(attach) 없음");
+      const sections = attach.sections.map((section) => ({ ...section })) as Array<
+        Record<string, unknown>
+      >;
+      const misses = attachShapes(sections, attach.pipes, attach.structures, attach.types);
+      const shapes = sections.map((section) =>
+        Object.fromEntries(
+          SHAPE_FIELDS.filter((key) => key in section).map((k) => [k, section[k]]),
+        ),
+      );
+      return { shapes, misses };
+    },
+    "cross.enforce": () => {
+      useDefinition(inputs.definition);
+      const input = inputs.cross_enforce;
+      if (!input) throw new Error("횡단 한 바퀴 입력(cross_enforce) 없음");
+      return enforceSavedCross(input, () => (input.grid ? gridAt(input.grid) : null));
+    },
+  };
+}
diff --git a/A00_Common/design/logic/design_calc_node_stages.ts b/A00_Common/design/logic/design_calc_node_stages.ts
index 235cd3c30..c394c75d1 100644
--- a/A00_Common/design/logic/design_calc_node_stages.ts
+++ b/A00_Common/design/logic/design_calc_node_stages.ts
@@ -77,7 +77,7 @@ export const STAGE_IDS = STAGE_NAMES.map((name) => `stage.${name}`);
 let gridMemo: { path: string; mtime: number; grid: DtmGrid } | null = null;
 
 /** DTM 격자 이진 — 같은 경로 · 같은 수정 시각이면 앞에 읽은 것(늘 떠 있는 Node). */
-function gridAt(path: string): DtmGrid {
+export function gridAt(path: string): DtmGrid {
   const mtime = statSync(path).mtimeMs;
   if (gridMemo?.path !== path || gridMemo.mtime !== mtime) {
     const bytes = readFileSync(path);
diff --git a/A00_Common/design/logic/design_calc_registry.ts b/A00_Common/design/logic/design_calc_registry.ts
index 79b0e5d37..17e250d21 100644
--- a/A00_Common/design/logic/design_calc_registry.ts
+++ b/A00_Common/design/logic/design_calc_registry.ts
@@ -217,10 +217,10 @@ export const CALC_REGISTRY: readonly CalcEntry[] = [
     site: "browser_now",
     stage: "cross",
     ts: `${B05L}B05_Profile_Sections_Ground.ts#extendUnclosed`,
-    runner: `py:${B06}B06_Section_Engine_SampleExtend.py#extend_unclosed`,
-    until: "472-4",
+    runner: "node:cross.enforce",
     pair: `${B06}B06_Section_Engine_SampleExtend.py#extend_unclosed`,
-    mirror: ["test_344_1_sections_ground_mirror"],
+    mirror: ["test_344_1_sections_ground_mirror", "test_511_b4_cross_save_mirror"],
+    note: "[저장] = Node cross.enforce 안(DTM 격자 · 511-B B-4) · DTM 아닌 지표면 = 파이썬 짝(표본기)",
   },
   {
     id: "ground.widen",
@@ -408,11 +408,10 @@ export const CALC_REGISTRY: readonly CalcEntry[] = [
     site: "browser_now",
     stage: "cross",
     ts: `${B06L}B06_Section_Cross_Enforce.ts#facilityRanges`,
-    runner: `py:${B06}B06_Section_Router_Design.py#enforce_design_lines`,
-    until: "472-4",
+    runner: "node:cross.enforce",
     pair: `${B06}B06_Section_Router_Design.py#enforce_design_lines`,
-    note: "구간 판정 = 파이썬 짝(Router_Design_Ranges) · 다시 세운 설계 = Node cross.design",
-    mirror: ["test_349_0n_cross_enforce_mirror"],
+    note: "[저장] 횡단 한 바퀴 = Node cross.enforce · 기본 설계 구간 = cross.design facilities(511-B B-4) · 파이썬 짝 = DTM 아닌 지표면 · Node 못 부를 때",
+    mirror: ["test_349_0n_cross_enforce_mirror", "test_511_b4_cross_save_mirror"],
   },
   {
     id: "cross.berm_spans",
@@ -451,11 +450,10 @@ export const CALC_REGISTRY: readonly CalcEntry[] = [
     site: "browser_now",
     stage: "cross",
     ts: `${U}common_util_structure_underdrain.ts#attachUnderdrainSpecs`,
-    runner: `py:${B06}B06_Section_Engine_Tilt.py#attach_underdrains`,
-    until: "472-4",
+    runner: "node:facility.attach",
     pair: `${B06}B06_Section_Engine_Tilt.py#attach_underdrains`,
     mirror: ["test_472_4_underdrain_mirror"],
-    note: "얹기 = GET 상세(파이썬) · 알려진 차 = 옛 underdrain 걷음 TS 만 · 기울임은 cross.design 안",
+    note: "얹기 = GET 상세 Node facility.attach 안(511-B B-4) · 알려진 차 = 옛 underdrain 걷음 TS 만 · 기울임은 cross.design 안",
   },
   {
     id: "cross.fit",
diff --git a/A00_Common/design/logic/design_calc_registry_facility.ts b/A00_Common/design/logic/design_calc_registry_facility.ts
index da11ddc46..6ff6ef648 100644
--- a/A00_Common/design/logic/design_calc_registry_facility.ts
+++ b/A00_Common/design/logic/design_calc_registry_facility.ts
@@ -85,10 +85,10 @@ export const FACILITY_ROWS: readonly CalcEntry[] = [
     site: "browser_now",
     stage: "cross",
     ts: `${U}common_util_structure_attach.ts#attachShapes`,
-    runner: `py:${B06}B06_Section_Engine_Attach.py#attach_shapes`,
-    until: "472-4",
+    runner: "node:facility.attach",
     pair: `${B06}B06_Section_Engine_Attach.py#attach_shapes`,
     mirror: ["test_323_4_attach_mirror"],
+    note: "GET 상세 · 재생성 = Node facility.attach(511-B B-4) · 파이썬 짝 = Node 못 부를 때",
   },
   {
     id: "facility.culvert_sets",
diff --git a/B06_Section/B06_Section_Engine_Attach.py b/B06_Section/B06_Section_Engine_Attach.py
index b76e642e5..a1f6b4ce7 100644
--- a/B06_Section/B06_Section_Engine_Attach.py
+++ b/B06_Section/B06_Section_Engine_Attach.py
@@ -2,6 +2,8 @@
 
 구조물 열쇠(`SHAPE_KEYS` · 빈칸 경고 `blank`)를 걷고 차례대로 다시 얹음 — 관 세트 → 벽 → 포장 → 맹암거 →
 빈칸 경고. 고르기 = 표 형상(322-1). 서버 상세 읽기(`_read_section_detail`) · 재생성 응답이 이것 하나를 씀.
+셈 = 늘 떠 있는 Node `facility.attach`(화면과 같은 TS · 511-B B-4) ·
+파이썬 몫(`_attach_python`)은 Node 를 못 부를 때만.
 TS 짝 = `common_util/common_util_structure_attach.ts` `attachShapes`(화면 = 초안 ?? 저장분 현황) ·
 거울 시험 = `resources/tester/test_323_4_attach_mirror.py`.
 """
@@ -106,14 +108,10 @@ def _outside_route(pipe: Any, sections: list[dict[str, Any]]) -> bool:
     return False
 
 
-def attach_shapes(
+def _attach_python(
     sections: list[dict[str, Any]], pipes: list[Any], structures: list[Any]
 ) -> dict[str, list[float]]:
-    """측점마다 그림 자료를 걷고 현황으로 다시 얹음(TS `attachShapes` 짝 · 제자리 고침) ·
-    시종점 밖 관 · 주인 측점 먼 관은 안 얹고 돌려줌(458 · `{"outside", "far"}`)."""
-    for section in sections:
-        for key in (*SHAPE_KEYS, "blank"):
-            section.pop(key, None)
+    """파이썬 짝(TS `attachShapes` · Node 를 못 부를 때만)."""
     misses: dict[str, list[float]] = {"outside": [], "far": []}
     kept = []
     for pipe in pipes:
@@ -131,6 +129,55 @@ def attach_shapes(
     )
     attach_underdrain_specs(sections, underdrains_from(structures))
     _attach_blanks(sections, pipes, structures)
+    return misses
+
+
+def _attach_node(
+    sections: list[dict[str, Any]], pipes: list[Any], structures: list[Any]
+) -> dict[str, list[float]] | None:
+    """늘 떠 있는 Node `facility.attach`(511-B B-4) — 측점 자리만 보내고 그림 자료 칸만 받음 ·
+    못 부르면 None."""
+    from dataclasses import asdict
+
+    from B05_Profile.B05_Profile_Structures_Schema import load_definition, load_structure_types
+    from common_util.common_util_calc_runner import run_calc
+
+    stubs = [
+        {key: section.get(key) for key in ("chainage_m", "center_x", "center_y")}
+        for section in sections
+    ]
+    results = run_calc(
+        ["facility.attach"],
+        {
+            "definition": load_definition(),
+            "attach": {
+                "sections": stubs,
+                "pipes": [asdict(pipe) for pipe in pipes],
+                "structures": [item.model_dump(mode="json") for item in structures],
+                "types": [item.model_dump(mode="json") for item in load_structure_types()],
+            },
+        },
+    )
+    if results is None:
+        return None
+    out = results["facility.attach"]
+    for section, shape in zip(sections, out["shapes"], strict=True):
+        section.update(shape)
+    return out["misses"]
+
+
+def attach_shapes(
+    sections: list[dict[str, Any]], pipes: list[Any], structures: list[Any]
+) -> dict[str, list[float]]:
+    """측점마다 그림 자료를 걷고 현황으로 다시 얹음(TS `attachShapes` 짝 · 제자리 고침) ·
+    시종점 밖 관 · 주인 측점 먼 관은 안 얹고 돌려줌(458 · `{"outside", "far"}`)."""
+    for section in sections:
+        for key in (*SHAPE_KEYS, "blank"):
+            section.pop(key, None)
+    misses = _attach_node(sections, pipes, structures)
+    if misses is None:
+        logger.warning("Node 형상 얹기 실패 — 파이썬 짝으로 얹음(%d 측점)", len(sections))
+        misses = _attach_python(sections, pipes, structures)
     if misses["outside"] or misses["far"]:
         logger.warning("B06 시설 그림 안 얹음 — 노선 밖 %s · 측점 멂 %s", *misses.values())
     return misses
diff --git a/B06_Section/B06_Section_Engine_Design_Node.py b/B06_Section/B06_Section_Engine_Design_Node.py
index 8cf5a24a0..f56ae204f 100644
--- a/B06_Section/B06_Section_Engine_Design_Node.py
+++ b/B06_Section/B06_Section_Engine_Design_Node.py
@@ -56,10 +56,11 @@ def _python(job: DesignJob, standard: dict[str, Any] | None) -> dict[str, Any] |
 Facilities = tuple[Path, list[float]]
 
 
-def facility_inputs(project_root: Path) -> dict[str, list[dict[str, Any]]]:
+def facility_inputs(project_root: Path) -> dict[str, list[dict[str, Any]] | None]:
     """TS `facilityRanges` 입력 — 관 = 지금 노선에 얹은 관 지점(`route_pipe_points`) · 구조물 정본.
 
-    못 읽은 쪽은 빈 목록(파이썬 `pavement_ranges` · `ford_surface_drops` 의 비치명 태도 그대로)."""
+    못 읽은 관 = 빈 목록 · 구조물 = None(포장 · 맹암거 구간 없음 · 소단 = 저장분 그대로 · 파이썬
+    `pavement_ranges` · `berm_specs_at` 의 비치명 태도 그대로)."""
     from dataclasses import asdict
 
     from B05_Profile.B05_Profile_Engine_Sections import route_pipe_points
@@ -70,11 +71,12 @@ def facility_inputs(project_root: Path) -> dict[str, list[dict[str, Any]]]:
     except Exception:  # noqa: BLE001 — 정본을 못 읽어도 설계 계산은 이어 간다
         logger.exception("B06 관 지점을 읽지 못했습니다 (시설 구간 없음으로 본다)")
         pipes = []
+    structures: list[dict[str, Any]] | None
     try:
         structures = [s.model_dump(mode="json") for s in load_structures(str(project_root))[1]]
     except Exception:  # noqa: BLE001
         logger.exception("B06 구조물 정본을 읽지 못했습니다 (포장 · 맹암거 구간 없음으로 본다)")
-        structures = []
+        structures = None
     return {"pipes": pipes, "structures": structures}
 
 
diff --git a/B06_Section/B06_Section_Server_Calc_Prebuild.py b/B06_Section/B06_Section_Server_Calc_Prebuild.py
index 0b8d11742..6a4fb0232 100644
--- a/B06_Section/B06_Section_Server_Calc_Prebuild.py
+++ b/B06_Section/B06_Section_Server_Calc_Prebuild.py
@@ -57,6 +57,8 @@ logger = logging.getLogger(__name__)
 
 ROOT = Path(__file__).resolve().parents[1]
 BUNDLE = ROOT / "config" / "server_calc_node" / "B06_Section_Server_Calc_Node.js"
+# 곡선부 확폭 입력 칸(파이썬 `curve_widening_args` · TS `SaveSection`)
+CURVE_KEYS = ("plan_radius_m", "curve_outer_side", "curve_widening_m")
 _NPM_SCRIPT = "build:server-calc"
 # 정본에 얹는 값만 받는다 — Node 가 다른 키를 내도 설계 데이터에 흘리지 않는다.
 # ⚠ **TS 쪽 `STRUCTURE_ROW_KEYS` 와 짝이다.** 한쪽만 늘리면 Node 가 값을 내도 여기서 조용히
@@ -229,6 +231,105 @@ def _enforce_stored_designs(
     enforce_ford_surface_drops(longitudinal, sections, project_root, standard)
 
 
+def design_grid_file(project_root: Path, params: dict[str, Any] | None) -> Path | None:
+    """설계 지형이 DTM 이면 격자 이진(`dtm_grid_file` · 표본기 `build_surface_sampler` 와
+    같은 npz) · DTM 아닌 지표면(tin · nurbs · …) · 못 엶 = None(파이썬 길)."""
+    from common_util.common_util_surface_sampler import dtm_grid_file
+
+    params = params or {}
+    if params.get("method") != "dtm" or not params.get("source_filter"):
+        return None
+    models = project_root / "B04_PreProcess" / "models"
+    smooth = models / f"dtm_{params['source_filter']}_smooth.npz"
+    npz = (
+        smooth
+        if params.get("smooth") and smooth.exists()
+        else smooth.with_name(f"dtm_{params['source_filter']}.npz")
+    )
+    try:
+        return dtm_grid_file(npz) if npz.is_file() else None
+    except (OSError, ValueError, KeyError) as exc:
+        logger.warning("서버 재계산: DTM 격자 이진을 못 만듦 — 파이썬 길 · %s", exc)
+        return None
+
+
+def _enforce_on_python(
+    longitudinal: dict[str, Any],
+    sections: list[dict[str, Any]],
+    project_root: Path,
+    standard: dict[str, Any] | None,
+    surface: dict[str, Any] | None,
+) -> None:
+    """파이썬 길(DTM 아닌 지표면 · Node 못 부름) — 설계선 → (미교차면 표본기) → 넓힘 ·
+    포장 · 하강."""
+    from B06_Section.B06_Section_Router_Design import enforce_design_lines
+
+    # 모든 측점 설계선을 저장 입력으로 먼저 다시 냄(139-6 · 노견 확장 · 측구 · 지반유형) — 미교차
+    # 판정도 새 설계로 해야 넓힘 지표면을 연다.
+    enforce_design_lines(longitudinal, sections, project_root, standard)
+    # 확정 지표면 — 미교차 측점이 있을 때만 연다(샘플 넓힘 ㉳ (가) · 없으면 여는 비용을 안 씀).
+    unclosed = any((item.get("design") or {}).get("slope_unclosed") for item in sections)
+    sampler = _surface_sampler(project_root, surface) if unclosed else None
+    _enforce_stored_designs(longitudinal, sections, project_root, standard, sampler)
+
+
+def _enforce_on_node(
+    longitudinal: dict[str, Any],
+    sections: list[dict[str, Any]],
+    project_root: Path,
+    standard: dict[str, Any] | None,
+    grid: Path,
+) -> bool:
+    """Node `cross.enforce` 한 부름(TS `B06_Section_Cross_Save.enforceSavedCross`) — 측점 설계 ·
+    넓힌 표본을 자리에서 갈고 넓힌 표본은 횡단 파일에 남김. 못 부르면 False(파이썬 길)."""
+    from B05_Profile.B05_Profile_Engine_Sections import find_cross_file
+    from B05_Profile.B05_Profile_Structures_Schema import load_definition
+    from B06_Section.B06_Section_Engine_Design_Node import facility_inputs, full_standard
+    from common_util.common_util_calc_runner import run_calc
+    from common_util.common_util_json import atomic_write_json
+    from config.config_system import STANDARD_ROCK_BOUNDARY_DEFAULT_OFFSET_M
+
+    keys = ("chainage_m", "design", "samples", "frame", *CURVE_KEYS)
+    profiles = longitudinal.get("design_profiles") or []
+    results = run_calc(
+        ["cross.enforce"],
+        {
+            "definition": load_definition(),
+            "cross_enforce": {
+                "profile": (profiles[0] or {}).get("samples") or [] if profiles else [],
+                "sections": [{k: s.get(k) for k in keys if k in s} for s in sections],
+                "standard": full_standard(standard),
+                "rockDefaultM": STANDARD_ROCK_BOUNDARY_DEFAULT_OFFSET_M,
+                **facility_inputs(project_root),
+                "grid": str(grid),
+            },
+        },
+    )
+    if results is None:
+        logger.warning("서버 재계산: Node 횡단 한 바퀴 실패 — 파이썬 길")
+        return False
+    cross_dir = project_root / "B06_Section" / "cross_sections"
+    for section, row in zip(sections, results["cross.enforce"], strict=True):
+        if not row:
+            continue
+        section["design"] = row["design"]
+        if row.get("samples"):
+            section["samples"] = row["samples"]
+            cross_path = find_cross_file(cross_dir, float(section.get("chainage_m") or 0.0))
+            if cross_path.is_file():
+                stored = json.loads(cross_path.read_text(encoding="utf-8"))
+                atomic_write_json(cross_path, {**stored, "samples": row["samples"]})
+            info = row.get("extended") or {}
+            logger.info(
+                "미교차 샘플 넓힘: 측점 %.3f 좌 +%sm 우 +%sm 지표면 끝 %s",
+                float(section.get("chainage_m") or 0.0),
+                info.get("left_m"),
+                info.get("right_m"),
+                info.get("surface_end"),
+            )
+    return True
+
+
 def refresh_alignment(longitudinal: dict[str, Any]) -> dict[str, Any] | None:
     """종단 경고를 저장 입력(base_pvi · 편집 · 정책 · 기준)으로 지금 코드가 다시 셈 — 옛 코드가
     쓴 경고가 남지 않게(472 덧 · 요구 272). 기하(계획고 · 곡선 · 표본 · 위반)는 저장값 그대로 —
@@ -324,24 +425,26 @@ async def _recompute(project_id: UUID | str, route_id: int) -> int:
     standard = stored_standard_cross_section(longitudinal_row)
     # 포장 구간·세월교 보정 — 고쳐진 설계 위에서 면적·유토곡선이 나와야 한다.
     before = [json.dumps(item.get("design"), sort_keys=True, default=str) for item in sections]
-    # 모든 측점 설계선을 저장 입력으로 먼저 다시 냄(139-6 · 노견 확장 · 측구 · 지반유형) — 미교차
-    # 판정도 새 설계로 해야 넓힘 지표면을 연다.
-    from B06_Section.B06_Section_Router_Design import enforce_design_lines
-
-    await asyncio.to_thread(
-        enforce_design_lines, detail.get("longitudinal") or {}, sections, project_root, standard
-    )
-    # 확정 지표면 — 미교차 측점이 있을 때만 연다(샘플 넓힘 ㉳ (가) · 없으면 여는 비용을 안 씀).
-    unclosed = any((item.get("design") or {}).get("slope_unclosed") for item in sections)
-    sampler = await asyncio.to_thread(_surface_sampler, project_root, surface) if unclosed else None
-    await asyncio.to_thread(
-        _enforce_stored_designs,
+    # 횡단 한 바퀴(설계선 → 미교차 넓힘 → 포장 → 세월교 하강) — DTM 이면 Node 한 부름
+    # (화면과 같은 TS · 511-B B-4) · DTM 아닌 지표면 · Node 못 부름 = 파이썬 길
+    grid = await asyncio.to_thread(design_grid_file, project_root, surface)
+    on_node = grid is not None and await asyncio.to_thread(
+        _enforce_on_node,
         detail.get("longitudinal") or {},
         sections,
         project_root,
         standard,
-        sampler,
+        grid,
     )
+    if not on_node:
+        await asyncio.to_thread(
+            _enforce_on_python,
+            detail.get("longitudinal") or {},
+            sections,
+            project_root,
+            standard,
+            surface,
+        )
     fixed = [
         item
         for index, item in enumerate(sections)
diff --git a/common_util/common_util_calc_runner.py b/common_util/common_util_calc_runner.py
index 3f94f9052..00b49c437 100644
--- a/common_util/common_util_calc_runner.py
+++ b/common_util/common_util_calc_runner.py
@@ -44,6 +44,8 @@ NODE_IDS = frozenset(
         "cross.berm_spans",
         "facility.rebase",
         "stations.carry",
+        "facility.attach",
+        "cross.enforce",
     }
 )
 # 시험 길(`design_calc_node_trial.ts` `TRIAL` 표와 같음) — 조작 중 브라우저 함수를 서버가 같은 TS 로
diff --git a/resources/tester/test_139_6_save_redesign.py b/resources/tester/test_139_6_save_redesign.py
index bf884c31f..11fa2d4b2 100644
--- a/resources/tester/test_139_6_save_redesign.py
+++ b/resources/tester/test_139_6_save_redesign.py
@@ -69,4 +69,5 @@ def test_서버_재계산이_먼저_돌고_미교차_판정은_그_뒤() -> None
     src = (PROJECT_ROOT / "B06_Section" / "B06_Section_Server_Calc_Prebuild.py").read_text(
         encoding="utf-8"
     )
-    assert src.index("enforce_design_lines, detail.get") < src.index("unclosed = any(")
+    # 파이썬 길(DTM 아닌 지표면) — 설계선 먼저 · Node 길 차례 = `test_511_b4_cross_save_mirror`
+    assert src.index("enforce_design_lines(longitudinal, sections") < src.index("unclosed = any(")
diff --git a/resources/tester/test_472_3_calc_registry.py b/resources/tester/test_472_3_calc_registry.py
index c1e3067ba..7c711a90e 100644
--- a/resources/tester/test_472_3_calc_registry.py
+++ b/resources/tester/test_472_3_calc_registry.py
@@ -48,6 +48,8 @@ NODE_IDS = {
     "cross.berm_spans",
     "facility.rebase",
     "stations.carry",
+    "facility.attach",  # 511-B B-4 — GET 형상 얹기
+    "cross.enforce",  # 511-B B-4 — [저장] 횡단 한 바퀴
 }
 
 pytestmark = pytest.mark.skipif(
diff --git a/resources/tester/test_511_b4_cross_save_mirror.py b/resources/tester/test_511_b4_cross_save_mirror.py
new file mode 100644
index 000000000..aa77912ea
--- /dev/null
+++ b/resources/tester/test_511_b4_cross_save_mirror.py
@@ -0,0 +1,251 @@
+"""PLAN 511-B B-4 (요구 320-4) — [저장] 횡단 한 바퀴 파이썬 길 = Node 길(`cross.enforce`) · 형상 얹기 Node.
+
+못박는 것
+  - 가짜 지형(DTM · 빈칸 = 지표면 끝) · 관 지점(세월교 · 물넘이포장 둘 · 배관) · 구조물(포장 · 맹암거 · 소단 ·
+    사토장)로 파이썬 길(`_enforce_on_python` = 설계선 → 표본기 넓힘 → 포장 → 하강)과 Node 길
+    (`_enforce_on_node` · TS `B06_Section_Cross_Save.enforceSavedCross`)의 측점 설계 · 넓힌 표본 0 차.
+  - 그 사이 넓힘 · 지표면 끝 · 포장 켬 · 끔 · 기울임 · 세월교 하강 · 소단 · 사용자 값 승계가 실제로 일어남.
+  - 구조물 정본을 못 읽으면 두 길 다 소단 = 저장분 그대로 · 포장 · 맹암거 구간 없음.
+  - DTM 아닌 지표면(tin) = 격자 없음(파이썬 길) · 형상 얹기 = Node(`facility.attach`) 부름.
+
+    ./venv/Scripts/python.exe -m pytest resources/tester/test_511_b4_cross_save_mirror.py -q
+"""
+
+from __future__ import annotations
+
+import copy
+import json
+import math
+import sys
+from pathlib import Path
+
+import numpy as np
+import pytest
+
+HERE = Path(__file__).resolve().parent
+ROOT = HERE.parents[1]
+for path in (ROOT, HERE):
+    if str(path) not in sys.path:
+        sys.path.insert(0, str(path))
+
+from test_349_0n_cross_enforce_mirror import PIPES  # noqa: E402
+
+import B05_Profile.B05_Profile_Engine_Sections as sections_mod  # noqa: E402
+import B05_Profile.B05_Profile_Structures_Repository as structures_repo  # noqa: E402
+import B06_Section.B06_Section_Engine_Tilt as tilt_mod  # noqa: E402
+import B06_Section.B06_Section_Router_Design_Ranges as ranges_mod  # noqa: E402
+from B05_Profile.B05_Profile_Structures_Schema import StructureInstance  # noqa: E402
+from B06_Section import B06_Section_Server_Calc_Prebuild as prebuild  # noqa: E402
+from B06_Section.B06_Section_Engine_Design import compute_cross_design  # noqa: E402
+from common_util.common_util_drainage_pipes import parse_pipe_points  # noqa: E402
+from common_util.common_util_surface_sampler import DtmGridSampler  # noqa: E402
+from config.config_system_design import STANDARD_CROSS_SECTION  # noqa: E402
+
+pytestmark = pytest.mark.skipif(
+    not (ROOT / "config" / "node_modules" / "vite").is_dir(), reason="프론트엔드 의존성 미설치"
+)
+
+SURFACE = {"method": "dtm", "source_filter": "classification", "smooth": False}
+STRUCTURES = [
+    StructureInstance(
+        structure_id="pv1", type_id="pavement_concrete", placement="interval", start_m=40, end_m=80
+    ),
+    StructureInstance(
+        structure_id="ud1",
+        type_id="cross_underdrain",
+        placement="point",
+        chainage_m=160,
+        options={"culvert_slope_pct": 2, "culvert_height_m": 0.5},
+    ),
+    StructureInstance(
+        structure_id="bm1",
+        type_id="berm",
+        placement="interval",
+        start_m=180,
+        end_m=230,
+        options={"width_m": 1.0, "interval_m": 3.0, "slope_deg": 0.0, "depth_m": 1.0},
+    ),
+    StructureInstance(
+        structure_id="sp1",
+        type_id="spoil_bank",
+        placement="site",
+        chainage_m=335,
+        options={"capacity_m3": 300, "side": "자동(성토 쪽)"},
+    ),
+]
+OFFSETS = [round(-20 + 0.5 * i, 1) for i in range(81)]
+
+
+def _plan(chainage: float) -> float:
+    return round(100.5 + 0.6 * math.sin(chainage / 53) + 0.002 * chainage, 4)
+
+
+def _npz(root: Path) -> None:
+    """DTM 격자 — y = 노선 왼쪽(+) · −42 m 아래 빈칸(지표면 끝) · x 180~240 은 −30 m 아래도."""
+    models = root / "B04_PreProcess" / "models"
+    models.mkdir(parents=True)
+    x = np.arange(-10.0, 431.0, 1.0)
+    y = np.arange(-80.0, 81.0, 1.0)
+    xx, yy = np.meshgrid(x, y)
+    # 가로 기울기 0.68 ~ 0.78(반폭 20 m 에서 안 닫히는 측점 · 닫히는 거리 갈림 · 지표면 끝)
+    z = 100 + (0.73 + 0.05 * np.sin(xx / 40)) * yy + 0.8 * np.sin(xx / 37) + 0.3 * np.cos(yy / 3)
+    valid = ~((yy < -42) | ((xx >= 180) & (xx <= 240) & (yy < -30)))
+    np.savez(models / f"dtm_{SURFACE['source_filter']}.npz", x=x, y=y, z=z, valid_mask=valid)
+
+
+def _sections(root: Path) -> tuple[dict, list[dict]]:
+    sampler = DtmGridSampler.from_npz(
+        root / "B04_PreProcess" / "models" / f"dtm_{SURFACE['source_filter']}.npz"
+    )
+    chainages = sorted({20.0 * i for i in range(21)} | {p["chainage_m"] for p in PIPES})
+    longitudinal = {
+        "design_profiles": [
+            {"samples": [{"chainage_m": c, "elevation_m": _plan(c)} for c in chainages]}
+        ]
+    }
+    out = []
+    for index, c in enumerate(chainages):
+        xy = np.array([[c, o] for o in OFFSETS])
+        z, _valid = sampler.sample_xy(xy)
+        samples = [
+            {
+                "offset_m": o,
+                "x": c,
+                "y": o,
+                "z": round(float(e), 6),
+                "elevation_m": round(float(e), 6),
+                "valid": True,
+            }
+            for o, e in zip(OFFSETS, z)
+        ]
+        # 저장분 = 옛 입력(포장 · 기울임 · 하강은 지금 시설과 다르게) + 사용자 값
+        options = dict(
+            ground_type="soil" if index % 3 == 0 else "ripping_rock",
+            section_mode="left_cut" if index % 2 else "right_cut",
+            ditch_type="standard",
+            paved=index % 4 == 0,
+            standard=STANDARD_CROSS_SECTION,
+            surface_drop_m=0.0,
+            shoulder_extend_left_m=0.3 if index % 5 == 0 else 0.0,
+        )
+        design = compute_cross_design(samples, _plan(c), **options)
+        design.update(status="provisional", pavement_suggested=False, structure_note="메모")
+        if index % 5 == 0:
+            design["shoulder_extend_left_m"] = 0.3
+        if index % 7 == 0:
+            design["cut_slope_ratio_user"] = 0.8
+        if index % 6 == 0:
+            design["berm"] = {"width_m": 1.5, "interval_m": 5.0, "slope_deg": 0.0, "depth_m": 2.0}
+            design["berm_depth_left_m"] = 0.5
+        out.append(
+            {
+                "chainage_m": c,
+                "center_x": c,
+                "center_y": 0.0,
+                "frame": {"origin": {"x": c, "y": 0.0}, "left_xy": [0.0, 1.0]},
+                "plan_radius_m": 60.0 if index == 4 else None,
+                "curve_outer_side": "left" if index == 4 else None,
+                "curve_widening_m": 0.5 if index == 4 else None,
+                "samples": samples,
+                "design": design,
+            }
+        )
+    return longitudinal, out
+
+
+def _facilities(monkeypatch, readable: bool = True) -> None:
+    pipes = parse_pipe_points(PIPES)
+
+    def structures(_root):
+        if not readable:
+            raise OSError("구조물 정본 못 읽음(시험)")
+        return 0, STRUCTURES
+
+    monkeypatch.setattr(sections_mod, "route_pipe_points", lambda *_a, **_k: pipes)
+    for module in (structures_repo, ranges_mod, tilt_mod):
+        monkeypatch.setattr(module, "load_structures", structures)
+
+
+def _both(tmp_path: Path, monkeypatch, readable: bool = True):
+    root = tmp_path / "p"
+    _npz(root)
+    _facilities(monkeypatch, readable)
+    longitudinal, sections = _sections(root)
+    py, node = copy.deepcopy(sections), copy.deepcopy(sections)
+    prebuild._enforce_on_python(longitudinal, py, root, None, SURFACE)
+    grid = prebuild.design_grid_file(root, SURFACE)
+    assert grid is not None and grid.is_file()
+    assert prebuild._enforce_on_node(longitudinal, node, root, None, grid)
+    return sections, py, node
+
+
+def _same(py: list[dict], node: list[dict]) -> None:
+    """값 0 차(수는 값으로 — Node 를 거친 저장분 칸은 5.0 이 5 로 옴)."""
+    for left, right in zip(py, node, strict=True):
+        assert left["samples"] == right["samples"], left["chainage_m"]
+        assert left["design"] == right["design"], left["chainage_m"]
+
+
+def test_저장_횡단_한_바퀴_파이썬_길_Node_길_0차(tmp_path, monkeypatch):
+    before, py, node = _both(tmp_path, monkeypatch)
+    _same(py, node)
+    by = {s["chainage_m"]: s for s in node}
+    widened = [s["chainage_m"] for s in node if len(s["samples"]) > len(OFFSETS)]
+    assert len(widened) >= 5, widened  # 넓힘이 실제로 돎
+    assert any(s["design"].get("slope_unclosed") for s in node)  # 지표면 끝까지 넓혀도 안 닫힘
+    assert (
+        by[60.0]["design"]["paved"] is True and by[100.0]["design"]["paved"] is False
+    )  # 포장 켬 · 끔
+    assert by[160.0]["design"]["tilted"] is True  # 맹암거 자리 기울임
+    assert by[250.0]["design"]["paved"] is True and by[250.0]["design"]["tilted"] is True  # 물넘이
+    assert by[110.0]["design"]["surface_drop_m"] > 0  # 세월교 하강
+    assert by[200.0]["design"]["berm"]["width_m"] == 1.0  # 소단 = 구조물 정본 구간
+    assert (
+        "berm" not in by[120.0]["design"] or by[120.0]["design"]["berm"] is None
+    )  # 구간 밖 = 없음
+    assert all(s["design"]["structure_note"] == "메모" for s in node)  # 사용자 값 승계
+    assert by[0.0]["design"]["shoulder_extend_left_m"] == 0.3
+    assert any(a["design"] != b["design"] for a, b in zip(before, node))
+
+
+def test_구조물_정본_못_읽음_소단_저장분_그대로(tmp_path, monkeypatch):
+    before, py, node = _both(tmp_path, monkeypatch, readable=False)
+    _same(py, node)
+    by = {s["chainage_m"]: s for s in node}
+    saved = {s["chainage_m"]: s for s in before}
+    assert by[0.0]["design"]["berm"] == saved[0.0]["design"]["berm"]  # 저장분 소단
+    assert by[60.0]["design"]["paved"] is False  # 포장 구간 없음(물넘이 밖)
+    assert not by[160.0]["design"].get("tilted")  # 맹암거 구간 없음(칸 없음)
+
+
+def test_DTM_아닌_지표면은_격자_없음(tmp_path):
+    root = tmp_path / "p"
+    _npz(root)
+    assert prebuild.design_grid_file(root, {**SURFACE, "method": "tin"}) is None
+    assert prebuild.design_grid_file(root, {**SURFACE, "source_filter": "없음"}) is None
+
+
+def test_형상_얹기는_Node(monkeypatch):
+    from B06_Section import B06_Section_Engine_Attach as attach_mod
+    from common_util import common_util_calc_runner as runner
+
+    calls = []
+    real = runner.run_calc
+    monkeypatch.setattr(
+        runner, "run_calc", lambda ids, inputs: calls.append(ids) or real(ids, inputs)
+    )
+    sections = [
+        {"chainage_m": float(c), "center_x": float(c), "center_y": 0.0} for c in range(0, 401, 10)
+    ]
+    misses = attach_mod.attach_shapes(sections, parse_pipe_points(PIPES), STRUCTURES)
+    assert calls == [["facility.attach"]]
+    assert misses == {"outside": [], "far": []}
+    keys = {k for s in sections for k in s} - {"chainage_m", "center_x", "center_y"}
+    assert {"ford", "ford_pavement", "culvert", "pavement", "underdrain"} <= keys
+    # 파이썬 짝(Node 못 부를 때)과 같음
+    py = [
+        {"chainage_m": s["chainage_m"], "center_x": s["center_x"], "center_y": 0.0}
+        for s in sections
+    ]
+    attach_mod._attach_python(py, parse_pipe_points(PIPES), STRUCTURES)
+    assert json.loads(json.dumps(py)) == json.loads(json.dumps(sections))