diff --git a/A00_Common/design/design_profile_base.ts b/A00_Common/design/design_profile_base.ts
index 423667a34..d9d3ea049 100644
--- a/A00_Common/design/design_profile_base.ts
+++ b/A00_Common/design/design_profile_base.ts
@@ -12,9 +12,11 @@ import {
   maxChainageOf,
 } from "../../B05_Profile/B05_Profile_UI_Profile_Layout";
 import { followMovedNodes, oneStationList } from "../../common_util/common_util_structure_station";
+import { readAlignment } from "../../B05_Profile/logic/B05_Profile_UI_Profile_Data";
 
 /** 계획선 측점 줄 = 측점 한 벌(서버 일반 + 지금 구조물 측점 · 272) — 표 · ▲▼ · 그래프 · 3D · 횡단 다시 셈(342-1)이
- *  같은 목록 · 사라진 구조물 측점의 꼭짓점은 서버와 같게 옮기거나 지움(`followMovedNodes`) · 늘 저장분에서 셈. */
+ *  같은 목록 · 사라진 구조물 측점의 꼭짓점은 서버와 같게 옮기거나 지우고 새 측점엔 세움(`followMovedNodes` · 427) ·
+ *  늘 저장분에서 셈. */
 export function listedBase(
   storedBase: AlignmentBase | null,
   detail: SectionDetailResponse | null,
@@ -35,7 +37,12 @@ export function listedBase(
     .filter((chainage) => !before.has(chainage.toFixed(3)));
   return {
     ...storedBase,
-    basePvi: followMovedNodes(storedBase.basePvi, gone, born),
+    basePvi: followMovedNodes(
+      storedBase,
+      gone,
+      born,
+      Object.keys(readAlignment(detail.longitudinal)?.edits.station_offsets ?? {}),
+    ),
     stations: list.map((station) => ({
       station_id: station.station_id,
       chainage_m: station.chainage_m,
diff --git a/B05_Profile/B05_Profile_Router_Confirm.py b/B05_Profile/B05_Profile_Router_Confirm.py
index f2fdbccb3..7fdbfaadb 100644
--- a/B05_Profile/B05_Profile_Router_Confirm.py
+++ b/B05_Profile/B05_Profile_Router_Confirm.py
@@ -12,9 +12,15 @@ from typing import Any
 from uuid import UUID
 
 import aiomysql
+import numpy as np
 
 from B03_FileInput.B03_FileInput_Repository import get_project_storage_relative_path
-from B05_Profile.B05_Profile_Engine_Grade_Alignment import chainage_key
+from B05_Profile.B05_Profile_Engine_Grade_Alignment import (
+    AlignmentPolicy,
+    build_curves,
+    chainage_key,
+    evaluate,
+)
 from B05_Profile.B05_Profile_Engine_Grade_Profile import rebuild_alignment_profile
 from B05_Profile.B05_Profile_Engine_Sections import (
     _load_pipe_points,
@@ -201,6 +207,53 @@ async def sync_uphill_overrides_into_designs(
 _SAME_STATION_M = 0.006
 
 
+def _seat_born_nodes(
+    stored: dict[str, Any], base: list[dict[str, Any]], born: list[float]
+) -> list[dict[str, Any]]:
+    """새 측점(`born`)에 자동 계획선 규칙(원지반 지남 · `pass_through`)으로 꼭짓점을 세움(427).
+
+    다른 꼭짓점 높이는 그대로 · 양 끝 밖 · 이미 꼭짓점 있는(0.006m 안) 자리는 건너뜀. 지반 = 저장
+    선형 표본(`samples`) · 곡선 = 편집 없이(`pass_through` 와 같음). TS 짝 = `followMovedNodes`
+    (common_util_structure_station.ts) · 거울 시험 = `resources/tester/test_427_1_follow_seat.py`.
+    """
+    samples = stored.get("samples") or []
+    if not base or len(samples) < 2:
+        return base
+    first, last = float(base[0]["chainage_m"]), float(base[-1]["chainage_m"])
+    fresh = [
+        value
+        for value in born
+        if first < value < last
+        and all(abs(value - float(node["chainage_m"])) >= _SAME_STATION_M for node in base)
+    ]
+    if not fresh:
+        return base
+    ground_s = np.array([float(row["chainage_m"]) for row in samples], dtype=np.float64)
+    ground_z = np.array([float(row["ground_elevation_m"]) for row in samples], dtype=np.float64)
+    rows = sorted(
+        [(float(node["chainage_m"]), float(node["elevation_m"]), node) for node in base]
+        + [(value, float(np.interp(value, ground_s, ground_z)), None) for value in fresh],
+        key=lambda row: row[0],
+    )
+    base_s = np.array([row[0] for row in rows], dtype=np.float64)
+    target = np.array([row[1] for row in rows], dtype=np.float64)
+    free = np.array([row[2] is None for row in rows])
+    policy = AlignmentPolicy.from_dict(stored.get("policy") or {})
+    base_z = target.copy()
+    for _ in range(20):
+        curves, _warnings = build_curves(base_s, base_z, policy)
+        error = np.where(free, target - evaluate(base_s, base_z, curves, base_s), 0.0)
+        if float(np.max(np.abs(error))) < 1e-6:
+            break
+        base_z = base_z + error
+    return [
+        node
+        if node is not None
+        else {"chainage_m": round(float(s), 6), "elevation_m": round(float(z), 6)}
+        for (s, _target, node), z in zip(rows, base_z.tolist())
+    ]
+
+
 def _follow_moved_stations(
     data: dict[str, Any], before: list[float], previous: list[float] | None = None
 ) -> dict[str, Any] | None:
@@ -208,7 +261,10 @@ def _follow_moved_stations(
 
     남기면 측점선 없는 변화점이 계획선을 꺾는다(192-1 — 관 769.28 → 769.38 뒤 두 자리에
     편집이 남아 0.1m 사이 −465% 계단). 반올림 차이(0.006m 안) · 옛 소수 측점의 정수 m 맞춤
-    자리(272)만 옮기고 나머지는 지운다.
+    자리(272)는 옮김. 옮긴 관 · 구조물(427 · 요구 255-2) — 짝 못 찾은 옛 측점과 새 측점이 같은
+    수면 차례대로 짝 · 높이 고친 꼭짓점(`station_offsets`)은 높이째 · 편집째 옮기고, 나머지 새
+    측점은 자동 계획선 규칙(원지반 지남 · `_seat_born_nodes`)으로 꼭짓점을 세움(되돌리면 처음
+    값) · 짝 없는 옛 측점 꼭짓점은 지움.
     측점 목록이 계획선 측점 줄과 달라져도 다시 센다(272). 다시 셌으면 새 등급 요약(DB 몫)을,
     아니면 `None`.
     """
@@ -236,6 +292,25 @@ def _follow_moved_stations(
         if near is None and snapped in after_keys and snapped not in before_keys:
             near = float(snapped)
         moves[chainage_key(old)] = None if near is None else chainage_key(near)
+    # 옮긴 관 · 구조물(427) — 짝 못 찾은 옛 측점 ↔ 새 측점(같은 수 · 차례대로)
+    previous_keys = before_keys if previous is None else {chainage_key(v) for v in previous}
+    taken = {key for key in moves.values() if key is not None}
+    born = sorted(
+        value
+        for value in after
+        if chainage_key(value) not in previous_keys and chainage_key(value) not in taken
+    )
+    lost = sorted((key for key, target in moves.items() if target is None), key=float)
+    offsets = (stored.get("edits") or {}).get("station_offsets") or {}
+    # 꼭짓점을 새로 세울 측점 — 짝이면 높이 안 고친 것만(편집 R 은 옮김) · 짝 없으면 새 측점 전부
+    seat = born
+    if lost and len(lost) == len(born):
+        seat = []
+        for old_key, value in zip(lost, born):
+            moves[old_key] = chainage_key(value)
+            if not any(abs(float(key) - float(old_key)) < _SAME_STATION_M for key in offsets):
+                seat.append(value)
+    reseat = {chainage_key(value) for value in seat}
 
     def moved(value: float) -> tuple[bool, str | None]:
         """옛 측점 0.006m 안이면 (참, 옮길 키 · 지우면 None) — 옛 글자(263.206)도 같은 측점(213-1).
@@ -269,8 +344,11 @@ def _follow_moved_stations(
             base.append(node)
             continue
         changed = True
-        if new_key is not None:
+        if new_key is not None and new_key not in reseat:
             base.append({**node, "chainage_m": float(new_key)})
+    seated = _seat_born_nodes(stored, base, seat)
+    changed = changed or len(seated) != len(base)
+    base = seated
     # 측점 목록만 바뀌어도 다시 셈 — 계획선 측점 줄(표 · ▲▼)이 옛 측점을 들고 남지 않게(272) ·
     # 줄이 없는 판은 맞추기 전 측점(`previous`)과 견줌
     rows = stored.get("stations")
diff --git a/common_util/common_util_structure_station.ts b/common_util/common_util_structure_station.ts
index 010b54541..64bd2f778 100644
--- a/common_util/common_util_structure_station.ts
+++ b/common_util/common_util_structure_station.ts
@@ -28,6 +28,12 @@
  * ========================================================================== */
 
 import { cardTitle, catalogRow, shapeNeeds } from "./common_util_structure_catalog";
+import {
+  buildCurves,
+  evaluateAt,
+  type AlignmentBase,
+  type AlignmentNode,
+} from "../B05_Profile/logic/B05_Profile_UI_Profile_Alignment";
 
 const EPS = 1e-6;
 
@@ -339,25 +345,90 @@ export function oneStationList<S extends ListedStation, P extends { chainage_m:
 }
 
 /**
- * 사라진 구조물 측점(`gone`)의 계획선 꼭짓점을 새 측점(`born`)으로 옮기거나 지운다 — 서버
- * `_follow_moved_stations`(B05_Profile_Router_Confirm.py) 짝: 0.006m 안 반올림 차이 · 옛 소수 측점의
- * 정수 m 맞춤 자리(272)면 높이 그대로 옮기고, 나머지는 지움(측점 없는 꼭짓점이 계획선을 꺾지 않게).
+ * 사라진 구조물 측점(`gone`)의 계획선 꼭짓점을 새 측점(`born`)으로 옮기거나 지우고 새로 세운다 — 서버
+ * `_follow_moved_stations` · `_seat_born_nodes`(B05_Profile_Router_Confirm.py) 짝: 0.006m 안 반올림 차이 ·
+ * 옛 소수 측점의 정수 m 맞춤 자리(272)면 높이 그대로 옮김. 옮긴 관 · 구조물(427) — 짝 못 찾은 옛 측점과
+ * 새 측점이 같은 수면 차례대로 짝 · 높이 고친 꼭짓점(`edited` = 저장 `station_offsets` 키)은 높이째 ·
+ * 나머지 새 측점은 자동 계획선 규칙(원지반 지남 · 다른 꼭짓점 그대로)으로 세움 · 짝 없는 옛 꼭짓점은 지움.
+ * 거울 시험 = `resources/tester/test_427_1_follow_seat.py`.
  */
-export function followMovedNodes<N extends { chainage_m: number }>(
-  nodes: ReadonlyArray<N>,
+export function followMovedNodes(
+  base: Pick<AlignmentBase, "basePvi" | "chainage" | "ground" | "policy">,
   gone: ReadonlyArray<number>,
   born: ReadonlyArray<number>,
-): N[] {
+  edited: ReadonlyArray<string> = [],
+): AlignmentNode[] {
   const target = (old: number): number | null => {
     const near = born.find((value) => Math.abs(value - old) < 0.006);
     if (near !== undefined) return near;
     const snapped = Math.floor(old + 0.5);
     return born.some((value) => Math.abs(value - snapped) < EPS) ? snapped : null;
   };
-  return nodes.flatMap((node) => {
+  const moves = new Map(gone.map((old) => [old, target(old)]));
+  const taken = [...moves.values()].filter((value): value is number => value !== null);
+  const left = [...born]
+    .filter((value) => taken.every((key) => Math.abs(key - value) >= EPS))
+    .sort((a, b) => a - b);
+  const lost = gone.filter((old) => moves.get(old) === null).sort((a, b) => a - b);
+  // 꼭짓점을 새로 세울 측점 — 짝이면 높이 안 고친 것만 · 짝 없으면 새 측점 전부
+  let seat = left;
+  if (lost.length && lost.length === left.length) {
+    seat = [];
+    lost.forEach((old, index) => {
+      moves.set(old, left[index]);
+      if (!edited.some((key) => Math.abs(Number(key) - old) < 0.006)) seat.push(left[index]);
+    });
+  }
+  const kept = base.basePvi.flatMap((node) => {
     const old = gone.find((value) => Math.abs(value - node.chainage_m) < 0.006);
     if (old === undefined) return [node];
-    const to = target(old);
-    return to === null ? [] : [{ ...node, chainage_m: to }];
+    const to = moves.get(old) ?? null;
+    return to === null || seat.includes(to) ? [] : [{ ...node, chainage_m: to }];
   });
+  return seatBornNodes(base, kept, seat);
+}
+
+/** 새 측점에 원지반을 지나는 꼭짓점(서버 `_seat_born_nodes` 짝 · `pass_through` 규칙 · 다른 꼭짓점 그대로). */
+function seatBornNodes(
+  base: Pick<AlignmentBase, "chainage" | "ground" | "policy">,
+  nodes: AlignmentNode[],
+  born: ReadonlyArray<number>,
+): AlignmentNode[] {
+  if (!nodes.length || base.chainage.length < 2) return nodes;
+  const first = nodes[0].chainage_m;
+  const last = nodes[nodes.length - 1].chainage_m;
+  const fresh = born.filter(
+    (value) =>
+      first < value &&
+      value < last &&
+      nodes.every((node) => Math.abs(value - node.chainage_m) >= 0.006),
+  );
+  if (!fresh.length) return nodes;
+  const rows = [
+    ...nodes.map((node) => ({
+      s: node.chainage_m,
+      z: node.elevation_m,
+      node: node as AlignmentNode | null,
+    })),
+    ...fresh.map((s) => ({ s, z: evaluateAt(base.chainage, base.ground, [], s), node: null })),
+  ].sort((a, b) => a.s - b.s);
+  const baseS = rows.map((row) => row.s);
+  const target = rows.map((row) => row.z);
+  let baseZ = [...target];
+  for (let round = 0; round < 20; round += 1) {
+    const pvi = baseS.map((s, index) => ({ chainage_m: s, elevation_m: baseZ[index] }));
+    const curves = buildCurves(pvi, base.policy, {}, []);
+    const error = rows.map((row, index) =>
+      row.node ? 0 : target[index] - evaluateAt(baseS, baseZ, curves, baseS[index]),
+    );
+    if (Math.max(...error.map(Math.abs)) < 1e-6) break;
+    baseZ = baseZ.map((z, index) => z + error[index]);
+  }
+  return rows.map(
+    (row, index) =>
+      row.node ?? {
+        chainage_m: Number(row.s.toFixed(6)),
+        elevation_m: Number(baseZ[index].toFixed(6)),
+      },
+  );
 }
diff --git a/resources/tester/helper_272_1_station_list.cjs b/resources/tester/helper_272_1_station_list.cjs
index d3b9fcefe..75cdb0cfe 100644
--- a/resources/tester/helper_272_1_station_list.cjs
+++ b/resources/tester/helper_272_1_station_list.cjs
@@ -15,6 +15,8 @@ function loadTs(file) {
   const box = { exports: {} };
   const localRequire = (request) => {
     if (CATALOG.isCatalogRequest(request)) return CATALOG;
+    // 427 — 꼭짓점 세움이 종단 선형(B05 logic)을 부름 · 상대 경로 TS 는 그대로 읽음
+    if (request.startsWith(".")) return loadTs(path.join(path.dirname(file), `${request}.ts`));
     throw new Error(`stub 없음: ${request} (${file})`);
   };
   new Function("exports", "module", "require", js)(box.exports, box, localRequire);
@@ -26,7 +28,7 @@ const station = loadTs("common_util/common_util_structure_station.ts");
 const out = {
   planted: station.plantedChainages(input.pipes, input.structures, input.types),
   list: station.oneStationList(input.server, input.fresh),
-  nodes: station.followMovedNodes(input.nodes, input.gone, input.born),
+  nodes: station.followMovedNodes(input.base, input.gone, input.born, input.edited),
 };
 // 368-2 추가 측점 — 화면이 둔 읽는 곳(setPlusStations)으로 심는 자리에 듦
 station.setPlusStations(() => input.plus);
diff --git a/resources/tester/helper_427_1_follow_seat.cjs b/resources/tester/helper_427_1_follow_seat.cjs
new file mode 100644
index 000000000..8abf14dca
--- /dev/null
+++ b/resources/tester/helper_427_1_follow_seat.cjs
@@ -0,0 +1,30 @@
+/* 427-1 관 · 구조물 옮김 때 꼭짓점 따라감 — 진짜 `common_util_structure_station.ts` 의 `followMovedNodes` 를
+ * Node 로 돌림. 입력 argv[2] JSON [{ base, gone, born, edited }, …] · 표준출력 = 꼭짓점 목록 한 벌씩.
+ */
+const fs = require("fs");
+const path = require("path");
+const ts = require(path.join(__dirname, "..", "..", "config", "node_modules", "typescript"));
+const CATALOG = require("./helper_322_catalog_module.cjs");
+
+const ROOT = path.join(__dirname, "..", "..");
+
+function loadTs(file) {
+  const js = ts.transpileModule(fs.readFileSync(path.join(ROOT, file), "utf8"), {
+    compilerOptions: { module: ts.ModuleKind.CommonJS, target: ts.ScriptTarget.ES2020 },
+  }).outputText;
+  const box = { exports: {} };
+  const localRequire = (request) => {
+    if (CATALOG.isCatalogRequest(request)) return CATALOG;
+    if (request.startsWith(".")) return loadTs(path.join(path.dirname(file), `${request}.ts`));
+    throw new Error(`stub 없음: ${request} (${file})`);
+  };
+  new Function("exports", "module", "require", js)(box.exports, box, localRequire);
+  return box.exports;
+}
+
+const cases = JSON.parse(fs.readFileSync(process.argv[2], "utf8"));
+const station = loadTs("common_util/common_util_structure_station.ts");
+const out = cases.map((item) =>
+  station.followMovedNodes(item.base, item.gone, item.born, item.edited),
+);
+process.stdout.write(JSON.stringify(out));
diff --git a/resources/tester/test_272_1_station_list.py b/resources/tester/test_272_1_station_list.py
index de9c205d1..845e8b0df 100644
--- a/resources/tester/test_272_1_station_list.py
+++ b/resources/tester/test_272_1_station_list.py
@@ -127,7 +127,16 @@ def ts(tmp_path_factory) -> dict:
         "types": _types(),
         "server": SERVER,
         "fresh": FRESH,
-        "nodes": fixture["profile_alignment"]["base_pvi"],
+        "base": {
+            "basePvi": fixture["profile_alignment"]["base_pvi"],
+            # 고정 사본엔 선형 표본이 없음 — 서버도 꼭짓점을 새로 안 세움(427)
+            "chainage": [s["chainage_m"] for s in fixture["profile_alignment"].get("samples", [])],
+            "ground": [
+                s["ground_elevation_m"] for s in fixture["profile_alignment"].get("samples", [])
+            ],
+            "policy": fixture["profile_alignment"]["policy"],
+        },
+        "edited": list(fixture["profile_alignment"]["edits"]["station_offsets"]),
         "gone": [s["chainage_m"] for s in fixture["stations"] if s.get("kind") == "irregular"],
         "born": [s["chainage_m"] for s in _snapped(fixture)],
         "plus": PLUS,
diff --git a/resources/tester/test_427_1_follow_seat.py b/resources/tester/test_427_1_follow_seat.py
new file mode 100644
index 000000000..6b5408ca1
--- /dev/null
+++ b/resources/tester/test_427_1_follow_seat.py
@@ -0,0 +1,197 @@
+"""427-1 관 · 구조물 옮김 때 종단 꼭짓점 따라감(요구 255-2 · 분석 424 2장 · 10장).
+
+까닭: 자동 계획선은 모든 측점이 꼭짓점(원지반 지남) · 관을 옮기면 옛 측점 꼭짓점만 지우고
+새 측점엔 안 세움 → 351 → 348 → 351 왕복 뒤 351 m 가 원지반보다 깎인 채 굳음.
+고침: 새 측점에 자동 계획선 규칙으로 꼭짓점을 세움 · 높이 고친 꼭짓점은 높이째 옮김
+→ 되돌리면 처음 값. 서버 `_follow_moved_stations` · `_seat_born_nodes` ↔ TS `followMovedNodes`
+(helper_427_1_follow_seat.cjs 가 진짜 TS 를 Node 로 돌림).
+"""
+
+from __future__ import annotations
+
+import copy
+import json
+import math
+import subprocess
+import sys
+from pathlib import Path
+
+import numpy as np
+import pytest
+
+HERE = Path(__file__).resolve().parent
+ROOT = HERE.parents[1]
+if str(ROOT) not in sys.path:
+    sys.path.insert(0, str(ROOT))
+
+from B05_Profile.B05_Profile_Engine_Grade import GradeDesignOptions  # noqa: E402
+from B05_Profile.B05_Profile_Engine_Grade_Alignment import (  # noqa: E402
+    AlignmentPolicy,
+    build_curves,
+    evaluate,
+)
+from B05_Profile.B05_Profile_Engine_Grade_Profile import (  # noqa: E402
+    design_ground_following_profile,
+    rebuild_alignment_profile,
+)
+from B05_Profile.B05_Profile_Router_Confirm import _merge_irregular_into_longitudinal  # noqa: E402
+
+REL = "B06_Section/longitudinal/longitudinal.json"
+PIPE = 351.0
+MOVED = 348.0
+
+
+def _ground(s: float) -> float:
+    return 100.0 + 0.08 * s + 1.5 * math.sin(s / 7.0)
+
+
+def _longitudinal(offsets: dict[str, float] | None = None) -> dict:
+    samples = [
+        {"chainage_m": float(s), "elevation_m": round(_ground(s), 6), "valid": True}
+        for s in range(0, 401)
+    ]
+    stations = [{"chainage_m": float(s), "kind": "regular"} for s in range(0, 401, 20)]
+    stations.append({"chainage_m": PIPE, "kind": "irregular", "structure": "파형강관 D800"})
+    stations.sort(key=lambda row: row["chainage_m"])
+    data = {"samples": samples, "stations": stations}
+    options = GradeDesignOptions(
+        max_grade_pct=14.0,
+        max_reverse_grade_pct=5.0,
+        min_vertical_radius_m=100.0,
+        min_curve_length_m=20.0,
+        min_tangent_length_m=20.0,
+        vertical_curve_skip_delta_pct=0.5,
+        design_speed_kph=20,
+    )
+    alignment, profile = design_ground_following_profile(data, options, station_interval_m=20.0)
+    data["profile_alignment"] = alignment
+    data["design_profiles"] = [profile]
+    if offsets:
+        alignment, profile = rebuild_alignment_profile(data, {"station_offsets": offsets})
+        data["profile_alignment"] = alignment
+        data["design_profiles"] = [profile]
+    return data
+
+
+def _write(tmp_path: Path, data: dict) -> None:
+    path = tmp_path / REL
+    path.parent.mkdir(parents=True, exist_ok=True)
+    path.write_text(json.dumps(data), encoding="utf-8")
+
+
+def _move(tmp_path: Path, *to: float) -> dict:
+    marks = [{"chainage_m": at, "kind": "irregular", "structure": "파형강관 D800"} for at in to]
+    _merge_irregular_into_longitudinal(tmp_path, REL, marks)
+    return json.loads((tmp_path / REL).read_text(encoding="utf-8"))
+
+
+def _rows(data: dict, low: float = 340, high: float = 360) -> dict[float, float]:
+    """측점 계획고(표 한 줄) — 기본 340~360 m."""
+    return {
+        row["chainage_m"]: row["plan_elevation_m"]
+        for row in data["profile_alignment"]["stations"]
+        if low <= row["chainage_m"] <= high
+    }
+
+
+def test_옛_판은_옮긴_자리에_꼭짓점이_없어_깎임() -> None:
+    """까닭 근거 — 꼭짓점을 지우기만 하면 351 m 계획선이 원지반을 안 지남."""
+    data = _longitudinal()
+    base = [n for n in data["profile_alignment"]["base_pvi"] if n["chainage_m"] != PIPE]
+    s = np.array([n["chainage_m"] for n in base])
+    z = np.array([n["elevation_m"] for n in base])
+    curves, _ = build_curves(s, z, AlignmentPolicy.from_dict(data["profile_alignment"]["policy"]))
+    assert abs(float(evaluate(s, z, curves, np.array([PIPE]))[0]) - _ground(PIPE)) > 0.2
+
+
+def test_옮긴_새_측점에_원지반_지나는_꼭짓점(tmp_path: Path) -> None:
+    _write(tmp_path, _longitudinal())
+    after = _move(tmp_path, MOVED)
+    base = [n["chainage_m"] for n in after["profile_alignment"]["base_pvi"]]
+    assert MOVED in base and PIPE not in base
+    rows = _rows(after)
+    assert MOVED in rows and PIPE not in rows
+    assert rows[MOVED] == pytest.approx(_ground(MOVED), abs=1e-4)
+
+
+def test_왕복하면_처음_계획고(tmp_path: Path) -> None:
+    first = _longitudinal()
+    _write(tmp_path, first)
+    _move(tmp_path, MOVED)
+    back = _move(tmp_path, PIPE)
+    before, after = _rows(first), _rows(back)
+    assert list(after) == list(before)
+    for at, value in before.items():
+        assert after[at] == pytest.approx(value, abs=5e-4), at
+    assert after[PIPE] == pytest.approx(_ground(PIPE), abs=1e-4)
+    assert _rows(back, 0, 400).keys() == _rows(first, 0, 400).keys()
+
+
+def test_높이_고친_꼭짓점은_높이째_옮김(tmp_path: Path) -> None:
+    first = _longitudinal({"351.000": 0.4})
+    _write(tmp_path, first)
+    moved = _move(tmp_path, MOVED)
+    assert moved["profile_alignment"]["edits"]["station_offsets"] == {"348.000": 0.4}
+
+    # 꼭짓점 높이(자동 높이 + 편집) 그대로 — 측점 계획고는 이웃 곡선 따라 조금 바뀜
+    def vertex(data: dict, at: float) -> float:
+        return next(
+            p["elevation_m"] for p in data["profile_alignment"]["pvi"] if p["chainage_m"] == at
+        )
+
+    assert vertex(moved, MOVED) == pytest.approx(vertex(first, PIPE), abs=1e-6)
+    back = _move(tmp_path, PIPE)
+    assert back["profile_alignment"]["edits"]["station_offsets"] == {"351.000": 0.4}
+    before, after = _rows(first), _rows(back)
+    for at, value in before.items():
+        assert after[at] == pytest.approx(value, abs=1e-6), at
+
+
+def test_짝_없는_새_측점도_세우고_옛_꼭짓점은_지움(tmp_path: Path) -> None:
+    """관 하나 지우고 둘 놓음(수가 다름) — 새 측점 둘 다 원지반 지남 · 옛 편집 지움."""
+    _write(tmp_path, _longitudinal({"351.000": 0.4}))
+    after = _move(tmp_path, 125.0, 287.0)
+    rows = _rows(after, 0, 400)
+    assert PIPE not in rows
+    assert after["profile_alignment"]["edits"]["station_offsets"] == {}
+    for at in (125.0, 287.0):
+        assert rows[at] == pytest.approx(_ground(at), abs=1e-4)
+
+
+def _ts(tmp_path: Path, cases: list[dict]) -> list[list[dict]]:
+    source = tmp_path / "in427.json"
+    source.write_text(json.dumps(cases, ensure_ascii=False), encoding="utf-8")
+    proc = subprocess.run(  # noqa: S603 — 고정 실행 파일
+        ["node", str(HERE / "helper_427_1_follow_seat.cjs"), str(source)],
+        capture_output=True,
+        text=True,
+        encoding="utf-8",
+        cwd=str(ROOT),
+        check=False,
+    )
+    assert proc.returncode == 0, proc.stderr
+    return json.loads(proc.stdout)
+
+
+@pytest.mark.parametrize(
+    ("offsets", "to"),
+    [(None, [MOVED]), ({"351.000": 0.4}, [MOVED]), (None, [125.0, 287.0])],
+)
+def test_화면_짝과_같은_꼭짓점(tmp_path: Path, offsets, to) -> None:
+    first = _longitudinal(offsets)
+    stored = copy.deepcopy(first["profile_alignment"])
+    _write(tmp_path, first)
+    server = _move(tmp_path, *to)["profile_alignment"]
+    base = {
+        "basePvi": stored["base_pvi"],
+        "chainage": [s["chainage_m"] for s in stored["samples"]],
+        "ground": [s["ground_elevation_m"] for s in stored["samples"]],
+        "policy": stored["policy"],
+    }
+    [nodes] = _ts(
+        tmp_path,
+        [{"base": base, "gone": [PIPE], "born": to, "edited": list(offsets or {})}],
+    )
+    assert [n["chainage_m"] for n in nodes] == [n["chainage_m"] for n in server["base_pvi"]]
+    for mine, theirs in zip(nodes, server["base_pvi"]):
+        assert mine["elevation_m"] == pytest.approx(theirs["elevation_m"], abs=1e-6)