From 314ce5351bff39e52e94fa2a3c44de1a51f07240 Mon Sep 17 00:00:00 2001
From: umsangdon <umsangdon@gmail.com>
Date: Sun, 18 Oct 2026 17:59:23 +0900
Subject: [PATCH] =?UTF-8?q?feat(B05=20=EC=A2=85=EB=8B=A8):=20=EC=B4=88?=
 =?UTF-8?q?=EA=B8=B0=20=EC=A2=85=EB=8B=A8=20R=20500=20=EB=84=98=EB=8A=94?=
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 =?UTF-8?q?=EC=97=86=EC=9D=8C=20=EA=B1=B7=EC=9D=8C=20(438)?=
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- 첫 계획선 · 균형 종단 맞춤 뒤 기본 L 20 기준 R > 500 m 꼭짓점 묶음을 앞뒤 꺾임(시종점)을 잇는 직선 위로 · 경계가 새로 R > 500 이면 묶음 늘려 다시(`straight_pass_through` ↔ TS `passThrough`)
- 정책 `no_curve_keys` · 열쇠 이어받기 걷음 — 옛 저장분 열쇠는 무시 · 꺾인 꼭짓점마다 곡선(모서리 없음)
- 균형 종단 꼭짓점 높이 소수 6자리 — 4자리면 직선 판정(426)이 꺾임으로 읽음
- 관 옮김 새 꼭짓점: 옮기기 전 계획선이 지반을 안 지나면(균형 종단) 그 계획선 높이(427 · 파이썬 ↔ TS)
- 시험 test_438_1 + 헬퍼 · test_432_1 고침

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XWh5wNNycMkbwMpACz1rte
---
 .../B05_Profile_Engine_Grade_Alignment.py     |  14 +-
 B05_Profile/B05_Profile_Engine_Grade_Carry.py |  40 +--
 .../B05_Profile_Engine_Grade_CurveLaw.py      |  46 ++--
 .../B05_Profile_Engine_Grade_Profile.py       |  55 +++-
 ...B05_Profile_Engine_RouteInitial_Profile.py |  15 +-
 B05_Profile/B05_Profile_Router_Confirm.py     |  23 +-
 .../B05_Profile_Router_RouteInitial.py        |  11 +-
 B05_Profile/logic/B05_Profile_Grade_Carry.ts  |  24 --
 B05_Profile/logic/B05_Profile_Grade_Ground.ts |  57 ++--
 B05_Profile/logic/B05_Profile_Grade_Seat.ts   |  25 +-
 .../logic/B05_Profile_Pipeline_Grade.ts       |  38 +--
 .../logic/B05_Profile_Profile_CurveLaw.ts     |  71 ++---
 .../logic/B05_Profile_UI_Profile_Alignment.ts |   6 +-
 config/config_system_design.py                |   5 +-
 resources/tester/helper_432_1_curve_law.cjs   |  17 +-
 resources/tester/helper_438_1_straighten.cjs  |  30 +++
 resources/tester/test_432_1_curve_law.py      | 111 ++------
 .../tester/test_438_1_initial_straighten.py   | 244 ++++++++++++++++++
 18 files changed, 516 insertions(+), 316 deletions(-)
 create mode 100644 resources/tester/helper_438_1_straighten.cjs
 create mode 100644 resources/tester/test_438_1_initial_straighten.py

diff --git a/B05_Profile/B05_Profile_Engine_Grade_Alignment.py b/B05_Profile/B05_Profile_Engine_Grade_Alignment.py
index 63b83395d..863e075b7 100644
--- a/B05_Profile/B05_Profile_Engine_Grade_Alignment.py
+++ b/B05_Profile/B05_Profile_Engine_Grade_Alignment.py
@@ -73,9 +73,6 @@ class AlignmentPolicy:
     #: 설계속도별 종단곡선 최소 R · L(m) — 미달 경고만(432 · 별표2 마.). 0이면 판정 안 함.
     min_vertical_radius_m: float = 0.0
     min_curve_length_m: float = 0.0
-    #: 초기값에서 곡선을 두지 않은 꼭짓점 열쇠(432 · `initial_no_curve_keys`) — 손 편집 · R 이면
-    #: 곡선.
-    no_curve_keys: tuple[str, ...] = ()
 
     @classmethod
     def from_config(
@@ -147,7 +144,6 @@ class AlignmentPolicy:
             paved=bool(payload.get("paved", False)),
             min_vertical_radius_m=float(payload.get("min_vertical_radius_m") or 0.0),
             min_curve_length_m=float(payload.get("min_curve_length_m") or 0.0),
-            no_curve_keys=tuple(str(key) for key in payload.get("no_curve_keys") or ()),
         )
 
     @property
@@ -180,7 +176,6 @@ class AlignmentPolicy:
             "hairpin_min_radius_m": self.hairpin_min_radius_m,
             "min_vertical_radius_m": self.min_vertical_radius_m,
             "min_curve_length_m": self.min_curve_length_m,
-            "no_curve_keys": list(self.no_curve_keys),
         }
 
 
@@ -310,7 +305,6 @@ def build_curves(
     curve_radii: dict[str, float] | None = None,
     *,
     only_explicit: bool = False,
-    edited: frozenset[str] = frozenset(),
 ) -> tuple[list[dict[str, Any]], list[str]]:
     """각 변화점에 대칭 종단곡선을 삽입하고 곡선 제원을 만든다.
 
@@ -339,9 +333,6 @@ def build_curves(
             continue  # 직선 판정 한 벌(426)
         if only_explicit and overrides.get(key) is None:
             continue
-        # 초기값 직선 꼭짓점(432) — 사용자가 고치거나(`edited`) R 을 넣기 전까지 곡선 없음
-        if key in policy.no_curve_keys and key not in edited and overrides.get(key) is None:
-            continue
         # 법정 다-(3)-(다)는 "종단곡선을 두지 않을 수 있다"는 허용 조항이다.
         # 실무 도면은 대수차가 작아도 변화점을 원곡선으로 처리하므로, 기본은 곡선을
         # 삽입하고 생략 가능 구간이라는 표시만 남긴다(config로 실제 생략 전환 가능).
@@ -539,11 +530,8 @@ def build_alignment(
     station_offsets, curve_radii = snapped["station_offsets"], snapped["curve_radii"]
 
     pvi_s, pvi_z, sources = resolve_pvi(base_s, base_z, station_offsets)
-    edited = frozenset(
-        chainage_key(s) for s, source in zip(pvi_s.tolist(), sources) if source == "user"
-    )
     curves, warnings = build_curves(
-        pvi_s, pvi_z, policy, curve_radii, only_explicit=only_explicit_curves, edited=edited
+        pvi_s, pvi_z, policy, curve_radii, only_explicit=only_explicit_curves
     )
     warnings += vertical_curve_shortfalls(
         curves, policy.min_vertical_radius_m, policy.min_curve_length_m
diff --git a/B05_Profile/B05_Profile_Engine_Grade_Carry.py b/B05_Profile/B05_Profile_Engine_Grade_Carry.py
index 713faf628..56c5d8784 100644
--- a/B05_Profile/B05_Profile_Engine_Grade_Carry.py
+++ b/B05_Profile/B05_Profile_Engine_Grade_Carry.py
@@ -207,50 +207,16 @@ def carry_edits(
     return out
 
 
-def carry_no_curve_keys(
-    old_xy: list[tuple[float, float]],
-    new_xy: list[tuple[float, float]],
-    old_keys: list[str],
-    ground_keys: list[str],
-    ground_pvi: list[dict[str, float]],
-    tol_m: float = SAME_LINE_TOL_M,
-) -> list[str]:
-    """새 꼭짓점의 초기값 직선 열쇠(432) — 같은 자리면 옛 꼭짓점 열쇠(꼭짓점 위일 때만) ·
-    바뀐 자리면 새 지반 첫 계획선 열쇠. 초기값만 · 그 뒤는 사용자 몫(요구 262)."""
-    match = line_matcher(old_xy, new_xy, tol_m)
-    old = [float(key) for key in old_keys]
-    ground = set(ground_keys)
-    out = []
-    for node in ground_pvi:
-        key = chainage_key(float(node["chainage_m"]))
-        s = match(float(node["chainage_m"]))
-        if (s is None and key in ground) or (
-            s is not None and any(abs(s - value) < _ON_NODE_M for value in old)
-        ):
-            out.append(key)
-    return out
-
-
 def carry_policy(
     old_xy: list[tuple[float, float]],
     new_xy: list[tuple[float, float]],
     old_alignment: dict[str, Any],
     new_alignment: dict[str, Any],
 ) -> dict[str, Any]:
-    """노선 [저장] 정책(432) — 새 정책에 옛 기본 L · 옮긴 직선 열쇠 · 옛 정책 없으면 새 정책."""
+    """노선 [저장] 정책(432) — 새 정책에 옛 기본 L · 옛 정책 없으면 새 정책. 바뀐 자리 새 꼭짓점은
+    새 지반 첫 계획선(직선화 438 · `carry_base`)."""
     new_policy = dict(new_alignment.get("policy") or {})
     old_policy = old_alignment.get("policy") or {}
     if not old_policy:
         return new_policy
-    keys = carry_no_curve_keys(
-        old_xy,
-        new_xy,
-        list(old_policy.get("no_curve_keys") or []),
-        list(new_policy.get("no_curve_keys") or []),
-        list(new_alignment.get("base_pvi") or []),
-    )
-    return {
-        **new_policy,
-        "default_curve_length_m": old_policy.get("default_curve_length_m"),
-        "no_curve_keys": keys,
-    }
+    return {**new_policy, "default_curve_length_m": old_policy.get("default_curve_length_m")}
diff --git a/B05_Profile/B05_Profile_Engine_Grade_CurveLaw.py b/B05_Profile/B05_Profile_Engine_Grade_CurveLaw.py
index ce984cb18..e9d454ffd 100644
--- a/B05_Profile/B05_Profile_Engine_Grade_CurveLaw.py
+++ b/B05_Profile/B05_Profile_Engine_Grade_CurveLaw.py
@@ -1,9 +1,9 @@
 """B05 종단곡선 초기값 직선 · 법정 미달 판정(432 · 요구 262).
 
-- `initial_no_curve_keys` : 초기값(자동설계 체인 · 추천 [적용]으로 처음 만드는 종단)에서만 — 기본 L
-  기준 R 이 `initial_straight_radius_m`(500 m)보다 큰(대수차 L/R 안쪽) 꼭짓점 열쇠. 정책
-  `no_curve_keys` 로 저장돼 그 꼭짓점엔 종단곡선을 두지 않음 · 사용자가 그 꼭짓점을 고치거나 R 을
-  넣으면 다시 곡선(`build_curves`). 꼭짓점 높이는 그대로.
+- `flat_bends` · `straighten_held` : 초기값(자동설계 체인 · 추천 [적용] · 노선 저장 때 새로 생긴
+  구간)에서만 — 기본 L 기준 R 이 `initial_straight_radius_m`(500 m)보다 큰(대수차 L/R 안쪽) 꼭짓점
+  묶음을 앞뒤 경계(진짜 꺾임 · 시종점)를 잇는 직선 위로 옮김(438 · 종단 직선화 단추와 같은 규칙).
+  직선 위 꼭짓점은 직선 판정(426)이라 곡선 없음 · 되풀이는 `straight_pass_through`.
 - `vertical_curve_shortfalls` : 설계속도별 종단곡선 최소 R · L 미달(지식DB 별표2 마.) — 막지 않고
   경고만 · 비포장 대수차 5 % 이하(생략 가능)는 뺌 · 45 % 규칙으로 줄어든 곡선도 같은 잣대.
 
@@ -20,20 +20,32 @@ from config.config_system import FOREST_ROAD_PROFILE_ALIGNMENT
 INITIAL_STRAIGHT_RADIUS_M = float(FOREST_ROAD_PROFILE_ALIGNMENT["initial_straight_radius_m"])
 
 
-def initial_no_curve_keys(
-    base_s: np.ndarray, base_z: np.ndarray, curve_length_m: float | None
-) -> tuple[str, ...]:
-    """안쪽 꼭짓점 중 기본 L 기준 R > 500 m(|대수차| < L/500) 인 것의 열쇠(소수 3자리)."""
+def flat_bends(base_s: np.ndarray, base_z: np.ndarray, curve_length_m: float | None) -> np.ndarray:
+    """안쪽 꼭짓점 중 기본 L 기준 R > 500 m(|대수차| < L/500) 인 것 — 시종점은 늘 False."""
+    flat = np.zeros(len(base_s), dtype=bool)
     if not curve_length_m or len(base_s) < 3:
-        return ()
-    limit = float(curve_length_m) / INITIAL_STRAIGHT_RADIUS_M
-    spans = base_s[1:] - base_s[:-1]
-    grades = (base_z[1:] - base_z[:-1]) / np.where(spans > 0, spans, 1.0)
-    keys = []
-    for index in range(1, len(base_s) - 1):
-        if abs(float(grades[index] - grades[index - 1])) < limit:
-            keys.append(f"{float(base_s[index]):.3f}")
-    return tuple(keys)
+        return flat
+    spans = np.diff(base_s)
+    grades = np.diff(base_z) / np.where(spans > 0, spans, 1.0)
+    flat[1:-1] = np.abs(np.diff(grades)) < float(curve_length_m) / INITIAL_STRAIGHT_RADIUS_M
+    return flat
+
+
+def straighten_held(base_s: np.ndarray, base_z: np.ndarray, held: np.ndarray) -> np.ndarray:
+    """`held` 꼭짓점 묶음마다 앞뒤 경계(held 아닌 꼭짓점)를 잇는 직선 위로 옮긴 표고."""
+    z = np.asarray(base_z, dtype=np.float64).copy()
+    index = 1
+    while index < len(z) - 1:
+        if not held[index]:
+            index += 1
+            continue
+        end = index
+        while end + 1 < len(z) - 1 and held[end + 1]:
+            end += 1
+        a, b = index - 1, end + 1
+        z[index:b] = np.interp(base_s[index:b], [base_s[a], base_s[b]], [z[a], z[b]])
+        index = b
+    return z
 
 
 def vertical_curve_shortfalls(
diff --git a/B05_Profile/B05_Profile_Engine_Grade_Profile.py b/B05_Profile/B05_Profile_Engine_Grade_Profile.py
index e303aaf6a..3ce1036ec 100644
--- a/B05_Profile/B05_Profile_Engine_Grade_Profile.py
+++ b/B05_Profile/B05_Profile_Engine_Grade_Profile.py
@@ -27,7 +27,7 @@
 """
 
 from collections import Counter
-from dataclasses import replace
+from collections.abc import Callable
 from typing import Any
 
 import numpy as np
@@ -46,7 +46,7 @@ from B05_Profile.B05_Profile_Engine_Grade_Alignment import (
     chainage_key,
     evaluate,
 )
-from B05_Profile.B05_Profile_Engine_Grade_CurveLaw import initial_no_curve_keys
+from B05_Profile.B05_Profile_Engine_Grade_CurveLaw import flat_bends, straighten_held
 from B05_Profile.B05_Profile_Engine_Grade_Solver import (
     grade_limits,
     integration_weights,
@@ -152,23 +152,57 @@ def _clearance_at(
     return best
 
 
-def pass_through(base_s: np.ndarray, target: np.ndarray, policy: AlignmentPolicy) -> np.ndarray:
+def pass_through(
+    base_s: np.ndarray,
+    target: np.ndarray,
+    policy: AlignmentPolicy,
+    held: np.ndarray | None = None,
+    hold: Callable[[np.ndarray], np.ndarray] | None = None,
+) -> np.ndarray:
     """종단곡선을 넣어도 계획선이 측점마다 `target` 을 지나게 하는 꼭짓점 표고.
 
     대칭 종단곡선은 꼭짓점을 지나지 않는다(중앙종거 |A|·L/8) — 보정 없이 곡선을 넣으면
     계획고가 목표에서 뜬다. 호가 측점 세로선과 만나는 점이 목표가 되도록 꼭짓점을
     밀어내며, 표고가 움직이면 대수차도 변하므로 수렴할 때까지 되풀이한다. 1차 종단(목표 =
     지반고)과 노선 추천 균형 종단 반영(목표 = 균형 종단, PLAN 74-4)이 함께 쓴다.
+    `held` 꼭짓점은 목표 대신 앞뒤 경계를 잇는 직선 위(438) · `hold` = 맞출 때마다 거는 제약(419-3).
     """
-    base_z = np.asarray(target, dtype=np.float64).copy()
+    held = np.zeros(len(base_s), dtype=bool) if held is None else held
+
+    def fit(z: np.ndarray) -> np.ndarray:
+        return straighten_held(base_s, z if hold is None else hold(z), held)
+
+    base_z = fit(np.asarray(target, dtype=np.float64))
     for _ in range(12):
         curves, _curve_warnings = build_curves(base_s, base_z, policy)
         error = target - evaluate(base_s, base_z, curves, base_s)
         error[0] = 0.0
         error[-1] = 0.0
+        error[held] = 0.0
         if float(np.max(np.abs(error))) < 1e-4:
             break
-        base_z = base_z + error
+        base_z = fit(base_z + error)
+    return base_z
+
+
+def straight_pass_through(
+    base_s: np.ndarray,
+    target: np.ndarray,
+    policy: AlignmentPolicy,
+    hold: Callable[[np.ndarray], np.ndarray] | None = None,
+) -> np.ndarray:
+    """초기값 맞춤(438 · 요구 265) — `pass_through` 뒤 기본 L 기준 R > 500 m 꼭짓점 묶음을 앞뒤
+    경계(진짜 꺾임 · 시종점)를 잇는 직선 위로 · 경계가 새로 R > 500 m 가 되면 묶음을 늘려 다시.
+    묶음은 커지기만 해 꼭짓점 수 안에 끝남. 짝 = TS `passThrough`
+    (`logic/B05_Profile_Grade_Ground.ts`).
+    """
+    held = np.zeros(len(base_s), dtype=bool)
+    for _ in range(len(base_s)):
+        base_z = pass_through(base_s, target, policy, held, hold)
+        flat = flat_bends(base_s, base_z, policy.default_curve_length_m) & ~held
+        if not flat.any():
+            break
+        held = held | flat
     return base_z
 
 
@@ -183,8 +217,8 @@ def design_ground_following_profile(
 
     규칙(2026-09-02 사용자 확정 + 2026-09-03 종단곡선 복원):
       - **모든 측점이 변화점**이고 그 자리 계획고는 지반고 그대로다. 절·성토가 거의 0이다.
-      - **변화점마다 종단곡선을 넣는다**(432: 기본 L 기준 R > 500 m 꼭짓점은 빼고 · 정책
-        `no_curve_keys`). 직선과 직선 사이에는 반드시 호가 있고, 호는
+      - **변화점마다 종단곡선을 넣는다**(438: 기본 L 기준 R > 500 m 꼭짓점 묶음은 앞뒤 꺾임을
+        잇는 직선 위로 · 직선이라 곡선 없음). 직선과 직선 사이에는 반드시 호가 있고, 호는
         변화점 대칭이라 **호의 중심이 측점 세로선 위**에 놓이며 좌우 직선과 접선을 이룬다.
       - 대칭 종단곡선은 꼭짓점을 지나지 않으므로 **호와 측점 세로선의 교점이 지반고**가
         되도록 꼭짓점 표고를 중앙종거만큼 밀어내며 반복 보정한다
@@ -240,11 +274,8 @@ def design_ground_following_profile(
     if note:
         warnings.append(note)
 
-    # 초기값 직선(432) — 기본 L 기준 R > 500 m 꼭짓점은 곡선 없이(꼭짓점 = 지반고 그대로)
-    policy = replace(
-        policy, no_curve_keys=initial_no_curve_keys(base_s, base_z, policy.default_curve_length_m)
-    )
-    base_z = pass_through(base_s, base_z, policy)
+    # 초기값 직선화(438) — 기본 L 기준 R > 500 m 꼭짓점 묶음은 앞뒤 꺾임을 잇는 직선 위
+    base_z = straight_pass_through(base_s, base_z, policy)
 
     alignment = build_alignment(
         base_s=base_s,
diff --git a/B05_Profile/B05_Profile_Engine_RouteInitial_Profile.py b/B05_Profile/B05_Profile_Engine_RouteInitial_Profile.py
index 8b58087b3..738d32384 100644
--- a/B05_Profile/B05_Profile_Engine_RouteInitial_Profile.py
+++ b/B05_Profile/B05_Profile_Engine_RouteInitial_Profile.py
@@ -277,8 +277,9 @@ def held_pass_through(
     계획고를 지나게 꼭짓점을 미는 `pass_through` 와 같은 되풀이에 직선 기울기 상한을 함께 둠(419-3).
 
     밀기만 하면 꼭짓점 사이 직선이 균형 종단 기울기보다 가팔라짐(검증_sub4 14 % → 14.47 %).
-    상한 = 균형 종단 측점 사이 가장 센 기울기(이미 상한 안 · 화면 겹침 상한도 그대로)."""
-    from B05_Profile.B05_Profile_Engine_Grade_Alignment import build_curves, evaluate
+    상한 = 균형 종단 측점 사이 가장 센 기울기(이미 상한 안 · 화면 겹침 상한도 그대로).
+    초기값 직선화(438) — 기본 L 기준 R > 500 m 꼭짓점 묶음은 앞뒤 꺾임을 잇는 직선 위."""
+    from B05_Profile.B05_Profile_Engine_Grade_Profile import straight_pass_through
 
     stations_a, plan_a = np.asarray(stations, float), np.asarray(plan, float)
     limit = float(np.abs(np.diff(plan_a) / np.diff(stations_a)).max())
@@ -286,15 +287,7 @@ def held_pass_through(
     legal = policy.max_grade_pct / 100.0
     limit = legal if legal <= limit <= legal + 1e-4 else limit + GRADE_EPS
     target = np.interp(base_s, stations_a, plan_a)
-    base_z = _hold(base_s, target, limit)
-    for _ in range(12):
-        curves, _warnings = build_curves(base_s, base_z, policy)
-        error = target - evaluate(base_s, base_z, curves, base_s)
-        error[0] = error[-1] = 0.0
-        if float(np.max(np.abs(error))) < 1e-4:
-            break
-        base_z = _hold(base_s, base_z + error, limit)
-    return base_z
+    return straight_pass_through(base_s, target, policy, lambda z: _hold(base_s, z, limit))
 
 
 def _dp(
diff --git a/B05_Profile/B05_Profile_Router_Confirm.py b/B05_Profile/B05_Profile_Router_Confirm.py
index 752271427..f03524cf5 100644
--- a/B05_Profile/B05_Profile_Router_Confirm.py
+++ b/B05_Profile/B05_Profile_Router_Confirm.py
@@ -211,6 +211,8 @@ async def sync_uphill_overrides_into_designs(
 #: 반올림만 다른 같은 측점(m) — 서버가 관 측점을 0.01m 로 반올림.
 #: 화면 `applyIrregularStations` 0.006 과 짝.
 _SAME_STATION_M = 0.006
+#: 지반 종단으로 볼 꼭짓점 자리 계획선 · 지반 어긋남 가운데값(m) — 새 꼭짓점을 지반에 세울지(438).
+_SEAT_GROUND_M = 0.01
 
 
 def _seat_born_nodes(
@@ -219,8 +221,10 @@ def _seat_born_nodes(
     """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 = `seatBornNodes`
-    (B05_Profile/logic/B05_Profile_Grade_Seat.ts) · 거울 시험 = `test_427_1_follow_seat.py`.
+    선형 표본(`samples`) · 곡선 = 편집 없이(`pass_through` 와 같음). 옮기기 전 계획선이 꼭짓점
+    대부분에서 지반을 안 지나면(균형 종단) 지반 대신 옮기기 전 계획선 높이(438). TS 짝 =
+    `seatBornNodes`(B05_Profile/logic/B05_Profile_Grade_Seat.ts) · 거울 시험 =
+    `test_427_1_follow_seat.py`.
     """
     samples = stored.get("samples") or []
     if not base or len(samples) < 2:
@@ -236,15 +240,26 @@ def _seat_born_nodes(
         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)
+    policy = AlignmentPolicy.from_dict(stored.get("policy") or {})
+    pre_s = np.array([float(node["chainage_m"]) for node in stored["base_pvi"]], dtype=np.float64)
+    pre_z = np.array([float(node["elevation_m"]) for node in stored["base_pvi"]], dtype=np.float64)
+    pre_curves, _warnings = build_curves(pre_s, pre_z, policy)
+    off = evaluate(pre_s, pre_z, pre_curves, pre_s) - np.interp(pre_s, ground_s, ground_z)
+    on_ground = float(np.median(np.abs(off))) < _SEAT_GROUND_M
+
+    def seat_z(value: float) -> float:
+        if on_ground:
+            return float(np.interp(value, ground_s, ground_z))
+        return float(evaluate(pre_s, pre_z, pre_curves, np.array([value]))[0])
+
     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],
+        + [(value, seat_z(value), 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)
diff --git a/B05_Profile/B05_Profile_Router_RouteInitial.py b/B05_Profile/B05_Profile_Router_RouteInitial.py
index 55a0f53e3..c2936fbd2 100644
--- a/B05_Profile/B05_Profile_Router_RouteInitial.py
+++ b/B05_Profile/B05_Profile_Router_RouteInitial.py
@@ -360,7 +360,6 @@ def _set_base_pvi(path: Path, stations: list[float], plan: list[float]) -> int:
     import numpy as np
 
     from B05_Profile.B05_Profile_Engine_Grade_Alignment import AlignmentPolicy
-    from B05_Profile.B05_Profile_Engine_Grade_CurveLaw import initial_no_curve_keys
     from B05_Profile.B05_Profile_Engine_RouteInitial_Profile import held_pass_through
     from common_util.common_util_json import atomic_write_json
 
@@ -368,19 +367,13 @@ def _set_base_pvi(path: Path, stations: list[float], plan: list[float]) -> int:
     alignment = longitudinal["profile_alignment"]
     base = alignment["base_pvi"]
     base_s = np.array([float(item["chainage_m"]) for item in base])
-    # 초기값 직선(432) — 균형 종단에서 기본 L 기준 R > 500 m 꼭짓점은 곡선 없이
-    policy = AlignmentPolicy.from_dict(alignment["policy"])
-    keys = initial_no_curve_keys(
-        base_s, np.interp(base_s, stations, plan), policy.default_curve_length_m
-    )
-    alignment["policy"]["no_curve_keys"] = list(keys)
     # 1차 종단과 같은 맞춤 — 종단곡선을 넣어도 측점마다 균형 종단 계획고를 지나게 · 꼭짓점 사이
-    # 직선은 균형 종단 상한 안(419-3)
+    # 직선은 균형 종단 상한 안(419-3) · R > 500 m 꼭짓점 묶음은 직선화(438)
     base_z = held_pass_through(
         base_s, stations, plan, AlignmentPolicy.from_dict(alignment["policy"])
     )
     for item, value in zip(base, base_z, strict=True):
-        item["elevation_m"] = round(float(value), 4)
+        item["elevation_m"] = round(float(value), 6)  # 직선 판정(426) 1e-5 m 안
     atomic_write_json(path, longitudinal)
     return len(base)
 
diff --git a/B05_Profile/logic/B05_Profile_Grade_Carry.ts b/B05_Profile/logic/B05_Profile_Grade_Carry.ts
index 7a01df662..cb8f6a18b 100644
--- a/B05_Profile/logic/B05_Profile_Grade_Carry.ts
+++ b/B05_Profile/logic/B05_Profile_Grade_Carry.ts
@@ -238,27 +238,3 @@ export function carryEdits(
   });
   return out;
 }
-
-/**
- * 새 꼭짓점의 초기값 직선 열쇠(432) — 같은 자리면 옛 꼭짓점 열쇠(꼭짓점 위일 때만) · 바뀐 자리면 새
- * 지반 첫 계획선 열쇠(파이썬 `carry_no_curve_keys` 짝). 초기값만 · 그 뒤는 사용자 몫(요구 262).
- */
-export function carryNoCurveKeys(
-  oldXy: ReadonlyArray<XY>,
-  newXy: ReadonlyArray<XY>,
-  oldKeys: ReadonlyArray<string>,
-  groundKeys: ReadonlyArray<string>,
-  groundPvi: ReadonlyArray<AlignmentNode>,
-  tolM: number = SAME_LINE_TOL_M,
-): string[] {
-  const match = lineMatcher(oldXy, newXy, tolM);
-  const old = oldKeys.map(Number);
-  const ground = new Set(groundKeys);
-  return groundPvi
-    .filter((node) => {
-      const s = match(node.chainage_m);
-      if (s === null) return ground.has(node.chainage_m.toFixed(3));
-      return old.some((value) => Math.abs(s - value) < ON_NODE_M);
-    })
-    .map((node) => node.chainage_m.toFixed(3));
-}
diff --git a/B05_Profile/logic/B05_Profile_Grade_Ground.ts b/B05_Profile/logic/B05_Profile_Grade_Ground.ts
index 866fc11d7..01e724e0a 100644
--- a/B05_Profile/logic/B05_Profile_Grade_Ground.ts
+++ b/B05_Profile/logic/B05_Profile_Grade_Ground.ts
@@ -14,7 +14,7 @@ import {
   type AlignmentNode,
   type AlignmentPolicy,
 } from "./B05_Profile_UI_Profile_Alignment";
-import { initialNoCurveKeys } from "./B05_Profile_Profile_CurveLaw";
+import { flatBends, straightenHeld } from "./B05_Profile_Profile_CurveLaw";
 
 /** 종단 지반 표본 한 점 — 저장 종단 `samples[]` 꼴. */
 export interface GroundSample {
@@ -67,33 +67,51 @@ export function groundProfile(
   return { chainage: rows.map((row) => row.s), ground: rows.map((row) => interp(fs, fz, row.s)) };
 }
 
-/** 종단곡선을 넣어도 측점마다 `target` 을 지나게 하는 꼭짓점 표고 — 파이썬 `pass_through` 짝. */
+/**
+ * 종단곡선을 넣어도 측점마다 `target` 을 지나게 하는 꼭짓점 표고 — 파이썬 `straight_pass_through` 짝.
+ * 초기값 직선화(438): 맞춘 뒤 기본 L 기준 R > 500 m 꼭짓점 묶음은 앞뒤 경계(진짜 꺾임 · 시종점)를
+ * 잇는 직선 위 · 경계가 새로 R > 500 m 가 되면 묶음을 늘려 다시(묶음은 커지기만).
+ */
 export function passThrough(baseS: number[], target: number[], policy: AlignmentPolicy): number[] {
-  let baseZ = [...target];
+  let held = baseS.map(() => false);
+  let baseZ = fitThrough(baseS, target, policy, held);
+  for (let round = 1; round < baseS.length; round += 1) {
+    const flat = flatBends(baseS, baseZ, policy.default_curve_length_m);
+    if (!flat.some((value, index) => value && !held[index])) break;
+    held = held.map((value, index) => value || flat[index]);
+    baseZ = fitThrough(baseS, target, policy, held);
+  }
+  return baseZ;
+}
+
+/** 파이썬 `pass_through` 짝 — `held` 꼭짓점은 목표 대신 앞뒤 경계를 잇는 직선 위. */
+function fitThrough(
+  baseS: number[],
+  target: number[],
+  policy: AlignmentPolicy,
+  held: boolean[],
+): number[] {
+  let baseZ = straightenHeld(baseS, target, held);
   for (let round = 0; round < 12; round += 1) {
     const pvi = baseS.map((s, index) => ({ chainage_m: s, elevation_m: baseZ[index] }));
     const curves = buildCurves(pvi, policy, {}, []);
-    const error = baseS.map((s, index) => target[index] - evaluateAt(baseS, baseZ, curves, s));
+    const error = baseS.map((s, index) =>
+      held[index] ? 0 : target[index] - evaluateAt(baseS, baseZ, curves, s),
+    );
     error[0] = 0;
     error[error.length - 1] = 0;
     if (Math.max(...error.map(Math.abs)) < 1e-4) break;
-    baseZ = baseZ.map((z, index) => z + error[index]);
+    baseZ = straightenHeld(
+      baseS,
+      baseZ.map((z, index) => z + error[index]),
+      held,
+    );
   }
   return baseZ;
 }
 
 /** 첫 계획선 꼭짓점(base_pvi · 0.000001 m) — 못 서는 땅이면 null(서버로 다시 셈). */
 export function groundFollowingBasePvi(input: GroundFollowingInput): AlignmentNode[] | null {
-  return groundFollowingPlan(input)?.pvi ?? null;
-}
-
-/**
- * 첫 계획선 꼭짓점 + 초기값 직선 열쇠(432) — 기본 L 기준 R > 500 m 꼭짓점은 곡선 없이(꼭짓점 =
- * 지반고 그대로) · 파이썬 `design_ground_following_profile` 의 `no_curve_keys` 짝.
- */
-export function groundFollowingPlan(
-  input: GroundFollowingInput,
-): { pvi: AlignmentNode[]; noCurveKeys: string[] } | null {
   const profile = groundProfile(input.samples);
   if (!profile) return null;
   const { chainage, ground } = profile;
@@ -114,14 +132,9 @@ export function groundFollowingPlan(
   const target = nodeS.map((s) => interp(chainage, ground, s));
   target[0] += input.startOffsetM ?? 0;
   target[target.length - 1] += input.endOffsetM ?? 0;
-  const noCurveKeys = initialNoCurveKeys(
-    nodeS.map((s, index) => ({ chainage_m: s, elevation_m: target[index] })),
-    input.policy.default_curve_length_m,
-  );
-  const baseZ = passThrough(nodeS, target, { ...input.policy, no_curve_keys: noCurveKeys });
-  const pvi = nodeS.map((s, index) => ({
+  const baseZ = passThrough(nodeS, target, input.policy);
+  return nodeS.map((s, index) => ({
     chainage_m: roundTo(s, 6),
     elevation_m: roundTo(baseZ[index], 6),
   }));
-  return { pvi, noCurveKeys };
 }
diff --git a/B05_Profile/logic/B05_Profile_Grade_Seat.ts b/B05_Profile/logic/B05_Profile_Grade_Seat.ts
index 7108f3dee..7d42b50c2 100644
--- a/B05_Profile/logic/B05_Profile_Grade_Seat.ts
+++ b/B05_Profile/logic/B05_Profile_Grade_Seat.ts
@@ -1,6 +1,7 @@
 /* =============================================================================
  * B05_Profile/logic/B05_Profile_Grade_Seat.ts
  * 옮긴 관 · 구조물의 새 측점에 계획선 꼭짓점 세움(427) — 원지반 지남(`passThrough` 규칙) · 다른 꼭짓점 그대로.
+ * 옮기기 전 계획선이 꼭짓점 대부분에서 지반을 안 지나면(균형 종단) 지반 대신 옮기기 전 계획선 높이(438).
  *
  * 짝 = 파이썬 `B05_Profile_Router_Confirm._seat_born_nodes` · 세울 측점은 공용 `followMovedNodes`
  * (common_util_structure_station.ts)가 고름 · 거울 시험 = resources/tester/test_427_1_follow_seat.py.
@@ -13,9 +14,19 @@ import {
   type AlignmentNode,
 } from "./B05_Profile_UI_Profile_Alignment";
 
+/** 지반 종단으로 볼 꼭짓점 자리 계획선 · 지반 어긋남 가운데값(m) — 파이썬 `_SEAT_GROUND_M`. */
+const SEAT_GROUND_M = 0.01;
+
+/** `np.median` 짝. */
+function median(values: number[]): number {
+  const sorted = [...values].sort((a, b) => a - b);
+  const mid = sorted.length >> 1;
+  return sorted.length % 2 ? sorted[mid] : (sorted[mid - 1] + sorted[mid]) / 2;
+}
+
 /** 새 측점(`born`)에 원지반을 지나는 꼭짓점 — 양 끝 밖 · 이미 꼭짓점 있는(0.006m 안) 자리는 건너뜀. */
 export function seatBornNodes(
-  base: Pick<AlignmentBase, "chainage" | "ground" | "policy">,
+  base: Pick<AlignmentBase, "chainage" | "ground" | "policy" | "basePvi">,
   nodes: AlignmentNode[],
   born: ReadonlyArray<number>,
 ): AlignmentNode[] {
@@ -29,13 +40,23 @@ export function seatBornNodes(
       nodes.every((node) => Math.abs(value - node.chainage_m) >= 0.006),
   );
   if (!fresh.length) return nodes;
+  const groundAt = (s: number): number => evaluateAt(base.chainage, base.ground, [], s);
+  // 옮기기 전 계획선(편집 없이) — 꼭짓점 대부분에서 지반을 지나면 지반 종단
+  const preS = base.basePvi.map((node) => node.chainage_m);
+  const preZ = base.basePvi.map((node) => node.elevation_m);
+  const preCurves = buildCurves(base.basePvi, base.policy, {}, []);
+  const onGround =
+    median(preS.map((s) => Math.abs(evaluateAt(preS, preZ, preCurves, s) - groundAt(s)))) <
+    SEAT_GROUND_M;
+  const seatZ = (s: number): number =>
+    onGround ? groundAt(s) : evaluateAt(preS, preZ, preCurves, s);
   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 })),
+    ...fresh.map((s) => ({ s, z: seatZ(s), node: null })),
   ].sort((a, b) => a.s - b.s);
   const baseS = rows.map((row) => row.s);
   const target = rows.map((row) => row.z);
diff --git a/B05_Profile/logic/B05_Profile_Pipeline_Grade.ts b/B05_Profile/logic/B05_Profile_Pipeline_Grade.ts
index f1fbef778..07b28bec4 100644
--- a/B05_Profile/logic/B05_Profile_Pipeline_Grade.ts
+++ b/B05_Profile/logic/B05_Profile_Pipeline_Grade.ts
@@ -32,15 +32,9 @@ import {
   type AlignmentBase,
   type AlignmentEdits,
 } from "./B05_Profile_UI_Profile_Alignment";
-import {
-  carryBase,
-  carryEdits,
-  carryNoCurveKeys,
-  changedSpan,
-  type XY,
-} from "./B05_Profile_Grade_Carry";
+import { carryBase, carryEdits, changedSpan, type XY } from "./B05_Profile_Grade_Carry";
 import { SECTION_STATION_INTERVAL_M } from "./B05_Profile_Sections_Stations";
-import { groundFollowingPlan, groundProfile } from "./B05_Profile_Grade_Ground";
+import { groundFollowingBasePvi, groundProfile } from "./B05_Profile_Grade_Ground";
 import { DEFAULT_CURVE_LENGTH_M } from "./B05_Profile_Profile_CurveLaw";
 
 const xy = (line: ReadonlyArray<Vertex>): Array<{ x: number; y: number }> =>
@@ -172,30 +166,18 @@ export function createPlanlineStage(deps: PlanlineDeps): StageFn<"planline"> {
     }));
     const profile = groundProfile(samples);
     if (!profile) return saved; // 못 서는 땅 — 저장 기준 그대로(서버가 [저장] 때 다시 셈)
-    // 바뀐 자리 새 꼭짓점 = 서버 새 지반 첫 계획선(기본 L = config 짝 · 초기값 직선 열쇠 · 432)
-    const plan = groundFollowingPlan({
-      samples,
-      stations: ground.stations.map((station) => station.chainageM),
-      policy: { ...saved.policy, default_curve_length_m: DEFAULT_CURVE_LENGTH_M },
-    });
-    const groundPvi = plan?.pvi ?? [];
+    // 바뀐 자리 새 꼭짓점 = 서버 새 지반 첫 계획선(기본 L = config 짝 · 초기값 직선화 · 438)
+    const groundPvi =
+      groundFollowingBasePvi({
+        samples,
+        stations: ground.stations.map((station) => station.chainageM),
+        policy: { ...saved.policy, default_curve_length_m: DEFAULT_CURVE_LENGTH_M },
+      }) ?? [];
     const savedLine = deps.savedLine();
     const span = savedLine ? changedSpan(xy(savedLine), xy(route.line)) : null;
     const savedPvi = deps.storedPvi?.() ?? saved.basePvi;
     return {
-      // 이어받은 구간 = 옛 정책(L · 직선 열쇠) · 바뀐 자리 새 꼭짓점만 새 열쇠(서버 `carry_policy` 짝)
-      policy: span
-        ? {
-            ...saved.policy,
-            no_curve_keys: carryNoCurveKeys(
-              xy(savedLine!),
-              xy(route.line),
-              saved.policy.no_curve_keys ?? [],
-              plan?.noCurveKeys ?? [],
-              groundPvi,
-            ),
-          }
-        : saved.policy,
+      policy: saved.policy, // 옛 기본 L 이어받음(서버 `carry_policy` 짝)
       onlyExplicitCurves: saved.onlyExplicitCurves,
       basePvi: span ? carryBase(xy(savedLine!), xy(route.line), savedPvi, groundPvi) : savedPvi,
       chainage: profile.chainage,
diff --git a/B05_Profile/logic/B05_Profile_Profile_CurveLaw.ts b/B05_Profile/logic/B05_Profile_Profile_CurveLaw.ts
index 9e1cfdb59..c09e28a0e 100644
--- a/B05_Profile/logic/B05_Profile_Profile_CurveLaw.ts
+++ b/B05_Profile/logic/B05_Profile_Profile_CurveLaw.ts
@@ -2,53 +2,64 @@
  * B05_Profile_Profile_CurveLaw.ts
  * 종단곡선 초기값 직선 · 법정 미달 판정(432 · 요구 262).
  *
- * 짝: 파이썬 `B05_Profile_Engine_Grade_CurveLaw.py`(`initial_no_curve_keys` ·
+ * 짝: 파이썬 `B05_Profile_Engine_Grade_CurveLaw.py`(`flat_bends` · `straighten_held` ·
  * `vertical_curve_shortfalls`) · config `FOREST_ROAD_PROFILE_ALIGNMENT` 의 `default_curve_length_m` ·
  * `initial_straight_radius_m` — 거울 시험 `test_432_1_curve_law.py`.
  *
- * - 초기값에서만 기본 L 기준 R > 500 m(|대수차| < L/500) 꼭짓점은 곡선 없음 — 정책 `no_curve_keys`
- *   로 얼려 두고, 사용자가 그 꼭짓점을 고치거나(source "user") R 을 넣으면 다시 기본 곡선.
+ * - 초기값에서만 기본 L 기준 R > 500 m(|대수차| < L/500) 꼭짓점 묶음을 앞뒤 경계(진짜 꺾임 · 시종점)를
+ *   잇는 직선 위로(438 · 종단 직선화 단추와 같은 규칙) — 직선 판정(426)이라 곡선 없음 · 되풀이는
+ *   `passThrough`(`B05_Profile_Grade_Ground.ts`).
  * - 법정 최소 R · L 미달은 막지 않고 경고 글만 · 비포장 대수차 5 % 이하(생략 가능)는 뺌.
  * ========================================================================== */
 
-import type {
-  AlignmentCurve,
-  AlignmentNode,
-  AlignmentPolicy,
-} from "./B05_Profile_UI_Profile_Alignment";
+import type { AlignmentCurve, AlignmentPolicy } from "./B05_Profile_UI_Profile_Alignment";
 
 /** 기본 종단곡선 길이 L(m) — config `default_curve_length_m` 짝(새 정책에 담겨 옴 · 옛 저장분은 저장값). */
 export const DEFAULT_CURVE_LENGTH_M = 20;
 /** 초기값 직선 문턱 R(m) — config `initial_straight_radius_m` 짝. */
 export const INITIAL_STRAIGHT_RADIUS_M = 500;
 
-/** 안쪽 꼭짓점 중 기본 L 기준 R > 500 m 인 것의 열쇠(소수 3자리) — 파이썬 `initial_no_curve_keys`. */
-export function initialNoCurveKeys(
-  nodes: ReadonlyArray<AlignmentNode>,
+/** 안쪽 꼭짓점 중 기본 L 기준 R > 500 m(|대수차| < L/500) 인 것 — 파이썬 `flat_bends` · 시종점 false. */
+export function flatBends(
+  baseS: ReadonlyArray<number>,
+  baseZ: ReadonlyArray<number>,
   curveLengthM: number | null | undefined,
-): string[] {
-  if (!curveLengthM || nodes.length < 3) return [];
+): boolean[] {
+  const flat = baseS.map(() => false);
+  if (!curveLengthM || baseS.length < 3) return flat;
   const limit = curveLengthM / INITIAL_STRAIGHT_RADIUS_M;
-  const keys: string[] = [];
-  for (let index = 1; index < nodes.length - 1; index += 1) {
-    const [a, b, c] = [nodes[index - 1], nodes[index], nodes[index + 1]];
-    const spanIn = b.chainage_m - a.chainage_m;
-    const spanOut = c.chainage_m - b.chainage_m;
-    const gradeIn = (b.elevation_m - a.elevation_m) / (spanIn > 0 ? spanIn : 1);
-    const gradeOut = (c.elevation_m - b.elevation_m) / (spanOut > 0 ? spanOut : 1);
-    if (Math.abs(gradeOut - gradeIn) < limit) keys.push(b.chainage_m.toFixed(3));
+  const grade = (index: number): number => {
+    const span = baseS[index + 1] - baseS[index];
+    return (baseZ[index + 1] - baseZ[index]) / (span > 0 ? span : 1);
+  };
+  for (let index = 1; index < baseS.length - 1; index += 1) {
+    flat[index] = Math.abs(grade(index) - grade(index - 1)) < limit;
   }
-  return keys;
+  return flat;
 }
 
-/** 초기값 직선 꼭짓점이라 곡선을 안 넣는가 — 사용자가 고친 꼭짓점 · R 지정이면 넣음. */
-export function skipsInitialCurve(
-  policy: AlignmentPolicy,
-  key: string,
-  node: AlignmentNode & { source?: string },
-  hasRequested: boolean,
-): boolean {
-  return !hasRequested && node.source !== "user" && (policy.no_curve_keys ?? []).includes(key);
+/** `held` 꼭짓점 묶음마다 앞뒤 경계(held 아닌 꼭짓점)를 잇는 직선 위로 — 파이썬 `straighten_held`. */
+export function straightenHeld(
+  baseS: ReadonlyArray<number>,
+  baseZ: ReadonlyArray<number>,
+  held: ReadonlyArray<boolean>,
+): number[] {
+  const z = [...baseZ];
+  let index = 1;
+  while (index < z.length - 1) {
+    if (!held[index]) {
+      index += 1;
+      continue;
+    }
+    let end = index;
+    while (end + 1 < z.length - 1 && held[end + 1]) end += 1;
+    const [a, b] = [index - 1, end + 1];
+    for (let k = index; k < b; k += 1) {
+      z[k] = z[a] + ((z[b] - z[a]) * (baseS[k] - baseS[a])) / (baseS[b] - baseS[a]);
+    }
+    index = b;
+  }
+  return z;
 }
 
 /** 법정 최소 R · L 을 못 채운 종단곡선 경고 글 — 파이썬 `vertical_curve_shortfalls` 와 같은 글. */
diff --git a/B05_Profile/logic/B05_Profile_UI_Profile_Alignment.ts b/B05_Profile/logic/B05_Profile_UI_Profile_Alignment.ts
index a026c3f2a..a68c8b485 100644
--- a/B05_Profile/logic/B05_Profile_UI_Profile_Alignment.ts
+++ b/B05_Profile/logic/B05_Profile_UI_Profile_Alignment.ts
@@ -15,7 +15,7 @@
 
 import { pivotAxes } from "./B05_Profile_UI_Profile_Pivot";
 import { isStraightBend } from "./B05_Profile_Profile_Straight";
-import { skipsInitialCurve, verticalCurveShortfalls } from "./B05_Profile_Profile_CurveLaw";
+import { verticalCurveShortfalls } from "./B05_Profile_Profile_CurveLaw";
 
 export interface AlignmentPolicy {
   station_interval_m: number;
@@ -36,10 +36,9 @@ export interface AlignmentPolicy {
   min_plan_radius_m?: number;
   /** 배향곡선 하한(m) — 이보다 급하면 경고만 낸다(2026-09-06 사용자 확정). */
   hairpin_min_radius_m?: number;
-  /** 종단곡선 법정 최소 R · L(m) · 초기값 곡선 없는 꼭짓점 열쇠(432 · `_Profile_CurveLaw`). */
+  /** 종단곡선 법정 최소 R · L(m) — 미달 경고만(432 · `_Profile_CurveLaw`). */
   min_vertical_radius_m?: number;
   min_curve_length_m?: number;
-  no_curve_keys?: string[];
 }
 
 export interface AlignmentNode {
@@ -321,7 +320,6 @@ export function buildCurves(
     const hasRequested = Number.isFinite(requested) && requested > 0;
     // 전체 측점 폴리라인 — 사용자가 R을 지정한 변화점에만 라운드가 생긴다.
     if (onlyExplicit && !hasRequested) continue;
-    if (skipsInitialCurve(policy, key, pvi[index], hasRequested)) continue; // 초기값 직선(432)
     const fallbackLength = Number.isFinite(policy.default_curve_length_m)
       ? (policy.default_curve_length_m as number)
       : policy.default_curve_radius_m * Math.abs(delta);
diff --git a/config/config_system_design.py b/config/config_system_design.py
index 092d8aed5..c973520a7 100644
--- a/config/config_system_design.py
+++ b/config/config_system_design.py
@@ -620,8 +620,9 @@ FOREST_ROAD_PROFILE_ALIGNMENT = {
     # 줄이고 경고를 남긴다(0으로 죽이지 않는다 — 2026-08-08 사용자 지시).
     # 사용자가 그 변화점 R을 직접 지정하면 그쪽이 이긴다. 호를 더/덜 길게 보이려면 여기만 고친다.
     "default_curve_length_m": 20.0,
-    # 초기값(자동설계 체인 · 추천 [적용]으로 처음 만드는 종단)에서만 — 기본 L 기준 R 이 이 값(m)보다
-    # 크면(대수차 L/R 안쪽) 그 꼭짓점에 종단곡선을 두지 않음(직선) · 그 뒤 손 편집은 기본 곡선.
+    # 초기값(자동설계 체인 · 추천 [적용] · 노선 저장 때 새로 생긴 구간)에서만 — 기본 L 기준 R 이
+    # 이 값(m)보다 큰(대수차 L/R 안쪽) 꼭짓점 묶음은 앞뒤 꺾임을 잇는 직선 위로(438) · 그 뒤는
+    # 사용자 몫.
     # TS 짝 = `B05_Profile/logic/B05_Profile_Profile_CurveLaw.ts` `INITIAL_STRAIGHT_RADIUS_M`.
     "initial_straight_radius_m": 500.0,
     # 인접 직선 길이 대비 곡선 반쪽이 점유할 수 있는 최대 비율.
diff --git a/resources/tester/helper_432_1_curve_law.cjs b/resources/tester/helper_432_1_curve_law.cjs
index a8a451c75..36b1c3350 100644
--- a/resources/tester/helper_432_1_curve_law.cjs
+++ b/resources/tester/helper_432_1_curve_law.cjs
@@ -1,5 +1,5 @@
 /* 432-1 종단곡선 초기값 직선 · 법정 미달 거울 헬퍼 — `logic/B05_Profile_Grade_Ground.ts`
- * `groundFollowingPlan` · `_UI_Profile_Alignment.ts` `buildAlignment` · `_Profile_CurveLaw.ts` 를
+ * `groundFollowingBasePvi` · `_UI_Profile_Alignment.ts` `buildAlignment` · `_Profile_CurveLaw.ts` 를
  * 그 자리에서 트랜스파일해 돌림. 입력 argv[2] JSON 파일 · 표준출력 JSON 한 벌.
  */
 const fs = require("fs");
@@ -28,10 +28,9 @@ const LOGIC = path.join(ROOT, "B05_Profile", "logic");
 const align = loadTs(path.join(LOGIC, "B05_Profile_UI_Profile_Alignment.ts"));
 const ground = loadTs(path.join(LOGIC, "B05_Profile_Grade_Ground.ts"));
 const law = loadTs(path.join(LOGIC, "B05_Profile_Profile_CurveLaw.ts"));
-const carry = loadTs(path.join(LOGIC, "B05_Profile_Grade_Carry.ts"));
 
 const input = JSON.parse(fs.readFileSync(process.argv[2], "utf8"));
-const plan = ground.groundFollowingPlan(input.ground);
+const pvi = ground.groundFollowingBasePvi(input.ground);
 const base = {
   policy: input.policy,
   onlyExplicitCurves: false,
@@ -50,18 +49,8 @@ const cases = input.edits.map((edits) => {
 });
 console.log(
   JSON.stringify({
-    pvi: plan ? plan.pvi : null,
-    keys: plan ? plan.noCurveKeys : null,
+    pvi,
     cases,
     consts: [law.DEFAULT_CURVE_LENGTH_M, law.INITIAL_STRAIGHT_RADIUS_M],
-    carried: input.carry
-      ? carry.carryNoCurveKeys(
-          input.carry.old_xy,
-          input.carry.new_xy,
-          input.carry.old_keys,
-          input.carry.ground_keys,
-          input.carry.ground_pvi,
-        )
-      : null,
   }),
 );
diff --git a/resources/tester/helper_438_1_straighten.cjs b/resources/tester/helper_438_1_straighten.cjs
new file mode 100644
index 000000000..88d6355f9
--- /dev/null
+++ b/resources/tester/helper_438_1_straighten.cjs
@@ -0,0 +1,30 @@
+/* 438-1 초기 종단 직선화 거울 헬퍼 — `logic/B05_Profile_Grade_Ground.ts` `groundFollowingBasePvi`
+ * (`passThrough` 직선화)를 그 자리에서 트랜스파일해 돌림. 입력 argv[2] JSON [GroundFollowingInput, …] ·
+ * 표준출력 = 꼭짓점 목록 한 벌씩.
+ */
+const fs = require("fs");
+const path = require("path");
+const ts = require(path.join(__dirname, "..", "..", "config", "node_modules", "typescript"));
+
+const cache = new Map();
+function loadTs(file) {
+  const full = path.resolve(file);
+  if (cache.has(full)) return cache.get(full);
+  const js = ts.transpileModule(fs.readFileSync(full, "utf8"), {
+    compilerOptions: { module: ts.ModuleKind.CommonJS, target: ts.ScriptTarget.ES2020 },
+  }).outputText;
+  const box = { exports: {} };
+  cache.set(full, box.exports);
+  const localRequire = (request) => {
+    if (request.startsWith(".")) return loadTs(path.join(path.dirname(full), `${request}.ts`));
+    return require(request);
+  };
+  new Function("exports", "module", "require", js)(box.exports, box, localRequire);
+  return box.exports;
+}
+
+const ground = loadTs(
+  path.join(__dirname, "..", "..", "B05_Profile", "logic", "B05_Profile_Grade_Ground.ts"),
+);
+const cases = JSON.parse(fs.readFileSync(process.argv[2], "utf8"));
+process.stdout.write(JSON.stringify(cases.map((item) => ground.groundFollowingBasePvi(item))));
diff --git a/resources/tester/test_432_1_curve_law.py b/resources/tester/test_432_1_curve_law.py
index 28efdd490..f6b127f8c 100644
--- a/resources/tester/test_432_1_curve_law.py
+++ b/resources/tester/test_432_1_curve_law.py
@@ -1,10 +1,10 @@
 # -*- coding: utf-8 -*-
-"""432-1 종단곡선 기본 L 20 m · 법정 미달 경고 · 초기값 R > 500 m 꼭짓점 = 곡선 없음(요구 262).
+"""432-1 종단곡선 기본 L 20 m · 법정 미달 경고(요구 262). 초기값 R > 500 m 꼭짓점 「곡선 없음」
+(정책 `no_curve_keys`)은 438 직선화로 바뀜 — `test_438_1_initial_straighten.py`.
 
 파이썬 `B05_Profile_Engine_Grade_CurveLaw.py` · `design_ground_following_profile` ·
-`build_alignment`
-(정책 `no_curve_keys`) ↔ TS `logic/B05_Profile_Profile_CurveLaw.ts` · `_Grade_Ground.ts`
-`groundFollowingPlan` · `_UI_Profile_Alignment.ts` 거울(`helper_432_1_curve_law.cjs`).
+`build_alignment` ↔ TS `logic/B05_Profile_Profile_CurveLaw.ts` · `_Grade_Ground.ts`
+`groundFollowingBasePvi` · `_UI_Profile_Alignment.ts` 거울(`helper_432_1_curve_law.cjs`).
 ./venv/Scripts/python.exe -m pytest resources/tester/test_432_1_curve_law.py -q
 """
 
@@ -26,12 +26,7 @@ from B05_Profile.B05_Profile_Engine_Grade_Alignment import (  # noqa: E402
     AlignmentPolicy,
     build_alignment,
 )
-from B05_Profile.B05_Profile_Engine_Grade_Carry import (  # noqa: E402
-    carry_base,
-    carry_no_curve_keys,
-    carry_policy,
-)
-from B05_Profile.B05_Profile_Engine_Grade_CurveLaw import initial_no_curve_keys  # noqa: E402
+from B05_Profile.B05_Profile_Engine_Grade_Carry import carry_base, carry_policy  # noqa: E402
 from B05_Profile.B05_Profile_Engine_Grade_Profile import (  # noqa: E402
     design_ground_following_profile,
 )
@@ -40,8 +35,8 @@ from config.config_system import FOREST_ROAD_PROFILE_ALIGNMENT  # noqa: E402
 # 20 m 마디 기울기(%) — 꼭짓점 대수차 1 · 6 · 0.5 · 7.5 · 0.5 · 7.5 · 5.5 · 0.5 · 3 %
 GRADES = [2.0, 3.0, 9.0, 9.5, 2.0, 2.5, 10.0, 4.5, 4.0, 1.0]
 STATIONS = [20.0 * i for i in range(len(GRADES) + 1)]
+# 432-1 때 곡선 없던 꼭짓점 열쇠 — 옛 저장분 정책에 남은 채 와도 무시(438)
 NO_CURVE = ["20.000", "60.000", "100.000", "160.000", "180.000"]
-CURVED = [40.0, 80.0, 120.0, 140.0]
 
 
 def _vertex_z() -> list[float]:
@@ -83,24 +78,19 @@ def _rebuild(alignment: dict, edits: dict, policy: dict | None = None) -> dict:
 
 EDITS = [
     {},
-    {"station_offsets": {"60.000": 0.1}},  # 그 꼭짓점 손 편집 → 기본 곡선
-    {"station_offsets": {"80.000": 0.2}},  # 이웃 손 편집 → 60 · 100 은 얼린 채
-    {"curve_radii": {"100.000": 800.0}},  # R 넣음 → 곡선
+    {"station_offsets": {"60.000": 0.1}},  # 직선 안 꼭짓점 손 편집 → 기본 곡선
+    {"station_offsets": {"80.000": 0.2}},
+    {"curve_radii": {"100.000": 800.0}},  # 직선 위 R → 직선 판정(426)이라 곡선 없음
 ]
 
 
-# 노선 [저장] — 끝 노드만 옮김(100 m 까지 같은 자리) · 옛 열쇠(추천) · 새 지반 열쇠
+# 노선 [저장] — 끝 노드만 옮김(100 m 까지 같은 자리)
 NEW_TOTAL = 100.0 + float(np.hypot(100.0, 30.0))
 NEW_STATIONS = [20.0 * i for i in range(11)] + [round(NEW_TOTAL, 3)]
 CARRY = {
     "old_xy": [(0.0, 0.0), (100.0, 0.0), (200.0, 0.0)],
     "new_xy": [(0.0, 0.0), (100.0, 0.0), (200.0, 30.0)],
-    "old_keys": NO_CURVE,
-    "ground_keys": ["140.000", "180.000"],
-    "ground_pvi": [{"chainage_m": s, "elevation_m": 0.0} for s in NEW_STATIONS],
 }
-# 같은 자리 옛 꼭짓점 열쇠(20 · 60 · 100) + 바뀐 자리 새 지반 열쇠(140 · 180) · 옛 160 은 버림
-CARRIED = ["20.000", "60.000", "100.000", "140.000", "180.000"]
 
 
 def _curve_at(alignment: dict) -> list[float]:
@@ -114,48 +104,27 @@ def test_기본_L_20_문턱_500_config_TS_짝():
     assert "DEFAULT_CURVE_LENGTH_M = 20;" in law and "INITIAL_STRAIGHT_RADIUS_M = 500;" in law
 
 
-def test_초기값_대수차_4퍼센트_안쪽은_곡선_없음(initial):
-    _long, _options, alignment, _profile = initial
-    assert alignment["policy"]["default_curve_length_m"] == 20.0
-    assert alignment["policy"]["no_curve_keys"] == NO_CURVE
-    assert _curve_at(alignment) == CURVED
-    # 꼭짓점 높이 그대로 — 곡선 없는 측점 계획고 = 지반고(원지반 지남)
-    rows = {round(r["chainage_m"], 3): r for r in alignment["stations"]}
-    for key in NO_CURVE:
-        row = rows[float(key)]
-        assert row["plan_elevation_m"] == pytest.approx(row["ground_elevation_m"], abs=1e-4)
-
-
 def test_법정_미달_경고_45퍼센트로_줄어든_곳도(initial):
     _long, options, alignment, _profile = initial
     assert options.min_vertical_radius_m == 100.0 and options.min_curve_length_m == 20.0
     assert alignment["policy"]["min_curve_length_m"] == 20.0
     # 20 m 마디 = 반쪽 9 m 한도 → L 18 m(줄어든 경고 글 그대로) + 법정 L 20 미달 경고
     lengths = [round(c["l_m"], 3) for c in alignment["curves"]]
-    assert lengths == [18.0] * len(CURVED)
+    assert lengths and lengths == [18.0] * len(lengths)
     reduced = [w for w in alignment["warnings"] if "줄였습니다" in w]
     short = [w for w in alignment["warnings"] if "미달" in w]
-    assert len(reduced) == len(CURVED) and len(short) == len(CURVED)
+    assert len(reduced) == len(lengths) and len(short) == len(lengths)
     assert short[0].startswith("40.0m: 종단곡선 R") and "법정 최소 R 100m · L 20m 미달" in short[0]
 
 
-def test_손_편집은_기본_곡선_이웃은_얼린_채(initial):
+def test_옛_저장분_열쇠는_무시_꺾인_꼭짓점마다_곡선(initial):
     alignment = initial[2]
-    own = _rebuild(alignment, EDITS[1])
-    assert 60.0 in _curve_at(own)
-    neighbor = _rebuild(alignment, EDITS[2])
-    assert 60.0 not in _curve_at(neighbor) and 100.0 not in _curve_at(neighbor)
-    assert 80.0 in _curve_at(neighbor)
-    radius = _rebuild(alignment, EDITS[3])
-    assert 100.0 in _curve_at(radius)
-
-
-def test_옛_저장분은_그대로(initial):
-    alignment = initial[2]
-    old = {**alignment["policy"], "default_curve_length_m": 15.0}
-    old.pop("no_curve_keys")
-    got = _rebuild(alignment, {}, old)
-    assert len(got["curves"]) == len(STATIONS) - 2  # 꼭짓점마다 곡선(옛 규칙)
+    old = {**alignment["policy"], "default_curve_length_m": 15.0, "no_curve_keys": NO_CURVE}
+    # 432-1 때 저장된 꼭짓점(지반 그대로 · 직선화 전)
+    nodes = [{"chainage_m": s, "elevation_m": z} for s, z in zip(STATIONS, _vertex_z())]
+    got = _rebuild({**alignment, "base_pvi": nodes}, {}, old)
+    assert len(got["curves"]) == len(STATIONS) - 2  # 꼭짓점마다 곡선 · 모서리 없음
+    assert "no_curve_keys" not in got["policy"]
 
 
 def test_TS_거울_첫_계획선_열쇠_곡선_경고(initial, tmp_path):
@@ -164,7 +133,7 @@ def test_TS_거울_첫_계획선_열쇠_곡선_경고(initial, tmp_path):
         "ground": {
             "samples": longitudinal["samples"],
             "stations": STATIONS,
-            "policy": {**alignment["policy"], "no_curve_keys": []},
+            "policy": alignment["policy"],
             "startOffsetM": options.start_elevation_offset_m,
             "endOffsetM": options.end_elevation_offset_m,
         },
@@ -174,11 +143,6 @@ def test_TS_거울_첫_계획선_열쇠_곡선_경고(initial, tmp_path):
         "groundZ": [row["elevation_m"] for row in longitudinal["samples"]],
         "stations": STATIONS,
         "edits": [{"station_offsets": {}, "curve_radii": {}, **e} for e in EDITS],
-        "carry": {
-            **CARRY,
-            "old_xy": [{"x": x, "y": y} for x, y in CARRY["old_xy"]],
-            "new_xy": [{"x": x, "y": y} for x, y in CARRY["new_xy"]],
-        },
     }
     source = tmp_path / "in.json"
     source.write_text(json.dumps(payload), encoding="utf-8")
@@ -192,12 +156,10 @@ def test_TS_거울_첫_계획선_열쇠_곡선_경고(initial, tmp_path):
     assert proc.returncode == 0, proc.stderr
     ts = json.loads(proc.stdout)
     assert ts["consts"] == [20, 500]
-    assert ts["keys"] == NO_CURVE
     assert [n["chainage_m"] for n in ts["pvi"]] == [n["chainage_m"] for n in alignment["base_pvi"]]
     assert [n["elevation_m"] for n in ts["pvi"]] == pytest.approx(
         [n["elevation_m"] for n in alignment["base_pvi"]], abs=1e-6
     )
-    assert ts["carried"] == CARRIED
     for edits, got in zip(EDITS, ts["cases"], strict=True):
         py = _rebuild(alignment, edits)
         assert [c[0] for c in got["curves"]] == pytest.approx(
@@ -212,42 +174,20 @@ def test_TS_거울_첫_계획선_열쇠_곡선_경고(initial, tmp_path):
         assert [w for w in got["warnings"] if "미달" in w] == py_short
 
 
-def test_추천_적용_균형_종단에서_열쇠(initial, tmp_path):
-    from B05_Profile.B05_Profile_Router_RouteInitial import _set_base_pvi
-
-    longitudinal, _options, alignment, _profile = initial
-    path = tmp_path / "long.json"
-    path.write_text(json.dumps({**longitudinal, "profile_alignment": alignment}), encoding="utf-8")
-    # 균형 종단 — 100 m 를 2 m 낮춤(그 둘레 대수차가 커짐 · 나머지는 지반 그대로)
-    plan = [z - (2.0 if s == 100.0 else 0.0) for s, z in zip(STATIONS, _vertex_z())]
-    _set_base_pvi(path, STATIONS, plan)
-    stored = json.loads(path.read_text(encoding="utf-8"))["profile_alignment"]["policy"]
-    expected = initial_no_curve_keys(np.array(STATIONS), np.array(plan), 20.0)
-    assert stored["no_curve_keys"] == list(expected)
-    assert "100.000" not in stored["no_curve_keys"] and "20.000" in stored["no_curve_keys"]
-
-
 def test_부르는_곳():
     def read(rel: str) -> str:
         return (ROOT / rel).read_text(encoding="utf-8")
 
-    assert "skipsInitialCurve(policy, key, pvi[index], hasRequested)" in read(
-        "B05_Profile/logic/B05_Profile_UI_Profile_Alignment.ts"
-    )
+    assert "skipsInitialCurve" not in read("B05_Profile/logic/B05_Profile_UI_Profile_Alignment.ts")
     assert "verticalCurveShortfalls(alignment.curves, policy)" in read(
         "B05_Profile/B05_Profile_UI_Profile_Balance.ts"
     )
-    assert "carryNoCurveKeys(" in read("B05_Profile/logic/B05_Profile_Pipeline_Grade.ts")
+    assert "carryNoCurveKeys" not in read("B05_Profile/logic/B05_Profile_Pipeline_Grade.ts")
     assert "carry_policy(old_xy, new_xy, old_alignment, alignment)" in read(
         "B05_Profile/B05_Profile_Route_Save.py"
     )
 
 
-def test_노선_저장_열쇠_옮김():
-    args = [CARRY[k] for k in ("old_xy", "new_xy", "old_keys", "ground_keys", "ground_pvi")]
-    assert carry_no_curve_keys(*args) == CARRIED
-
-
 def test_추천_적용_종단_노선_고쳐_저장_안_바뀐_구간_그대로(initial, tmp_path):
     from B05_Profile.B05_Profile_Router_RouteInitial import _set_base_pvi
 
@@ -258,7 +198,7 @@ def test_추천_적용_종단_노선_고쳐_저장_안_바뀐_구간_그대로(i
     _set_base_pvi(path, STATIONS, plan)
     old = json.loads(path.read_text(encoding="utf-8"))["profile_alignment"]
     old_rebuilt = _rebuild(old, {})
-    # 새 노선 종단 = 서버가 새로 냄(정책 config · L 20 · 새 지반 열쇠) → 옛 정책 · 옛 꼭짓점 이어받음
+    # 새 노선 종단 = 서버가 새로 냄(정책 config · L 20 · 직선화) → 옛 L · 옛 꼭짓점 이어받음
     zs = _vertex_z()
     samples = [
         {"chainage_m": float(s), "elevation_m": float(np.interp(s, STATIONS, zs))}
@@ -283,7 +223,4 @@ def test_추천_적용_종단_노선_고쳐_저장_안_바뀐_구간_그대로(i
     after = [(c["chainage_m"], round(c["r_m"], 3)) for c in carried["curves"]]
     # 안 바뀐 구간(< 80 m · 끝 노드 영향 밖) R · 직선 그대로
     assert [c for c in after if c[0] < 80] == [c for c in before if c[0] < 80]
-    old_keys = set(old["policy"]["no_curve_keys"])
-    assert {k for k in policy["no_curve_keys"] if float(k) <= 100} == {
-        k for k in old_keys if float(k) <= 100
-    }
+    assert "no_curve_keys" not in policy
diff --git a/resources/tester/test_438_1_initial_straighten.py b/resources/tester/test_438_1_initial_straighten.py
new file mode 100644
index 000000000..c142b4cfa
--- /dev/null
+++ b/resources/tester/test_438_1_initial_straighten.py
@@ -0,0 +1,244 @@
+# -*- coding: utf-8 -*-
+"""438-1 초기 종단 — R 500 넘는 꼭짓점 묶음 직선화(요구 262 · 265).
+
+초기값(1차 지반 종단 · 추천 [적용] 균형 종단)만 — 기본 L 20 기준 R > 500 m(|대수차| < 4 %)
+꼭짓점 묶음을 앞뒤 경계(진짜 꺾임 · 시종점)를 잇는 직선 위로 · 경계가 새로 R > 500 m 가 되면
+묶음을 늘려 다시. 432-1 「곡선 없음 · 높이 그대로」(`no_curve_keys`)는 걷음 — 모서리 원인.
+관 옮김(427) 새 꼭짓점은 지반 종단이 아니면 옮기기 전 계획선 높이.
+
+파이썬 `straight_pass_through` · `held_pass_through` · `_set_base_pvi` · `_seat_born_nodes` ↔ TS
+`groundFollowingBasePvi`(`helper_438_1_straighten.cjs`) · `seatBornNodes`(427 헬퍼).
+./venv/Scripts/python.exe -m pytest resources/tester/test_438_1_initial_straighten.py -q
+"""
+
+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.parent.parent
+sys.path.insert(0, str(ROOT))
+sys.path.insert(0, str(HERE))
+
+from test_427_1_follow_seat import (  # noqa: E402
+    MOVED,
+    PIPE,
+    _move,
+    _ts,
+    _write,
+)
+from test_427_1_follow_seat import _longitudinal as _long_427  # noqa: E402
+
+from B05_Profile.B05_Profile_Engine_Grade import resolve_grade_options  # noqa: E402
+from B05_Profile.B05_Profile_Engine_Grade_Alignment import (  # noqa: E402
+    AlignmentPolicy,
+    build_alignment,
+    build_curves,
+    evaluate,
+    is_straight_bend,
+)
+from B05_Profile.B05_Profile_Engine_Grade_CurveLaw import flat_bends  # noqa: E402
+from B05_Profile.B05_Profile_Engine_Grade_Profile import (  # noqa: E402
+    design_ground_following_profile,
+    pass_through,
+    rebuild_alignment_profile,
+)
+
+L_M = 20.0
+
+
+def _wave(s: float) -> float:
+    return 100.0 + 0.05 * s + 0.6 * math.sin(s / 45.0) + 0.08 * math.sin(s / 9.0)
+
+
+def _from_grades(grades: list[float]) -> tuple[list[float], list[float]]:
+    stations = [20.0 * i for i in range(len(grades) + 1)]
+    z = [100.0]
+    for grade in grades:
+        z.append(z[-1] + grade / 100.0 * 20.0)
+    return stations, z
+
+
+def _longitudinal(stations: list[float], height) -> dict:
+    samples = [
+        {"chainage_m": float(s), "elevation_m": round(float(height(s)), 6)}
+        for s in np.arange(0.0, stations[-1] + 0.5, 1.0)
+    ]
+    return {"samples": samples, "stations": [{"chainage_m": s} for s in stations]}
+
+
+WAVE_STATIONS = [20.0 * i for i in range(31)]
+WAVE = _longitudinal(WAVE_STATIONS, _wave)
+# 경계가 새로 R > 500 이 됨 — 20 m(대수차 −2 %) 직선화 뒤 40 m 대수차 3.5 → 2.5 %(맞춤 뒤 ×1.2 쯤)
+GROW_STATIONS, GROW_Z = _from_grades([2.0, 0.0, 3.5, 8.0, 4.0])
+GROW = _longitudinal(GROW_STATIONS, lambda s: np.interp(s, GROW_STATIONS, GROW_Z))
+OPTIONS = resolve_grade_options("trunk", terrain_type="normal")
+
+
+def _design(longitudinal: dict) -> dict:
+    return design_ground_following_profile(longitudinal, OPTIONS)[0]
+
+
+def _arrays(nodes: list[dict]) -> tuple[np.ndarray, np.ndarray]:
+    return (
+        np.array([float(n["chainage_m"]) for n in nodes]),
+        np.array([float(n["elevation_m"]) for n in nodes]),
+    )
+
+
+def _straight_mask(s: np.ndarray, z: np.ndarray) -> np.ndarray:
+    grades = np.diff(z) / np.diff(s)
+    mask = np.zeros(len(s), dtype=bool)
+    for i in range(1, len(s) - 1):
+        mask[i] = is_straight_bend(grades[i] - grades[i - 1], s[i] - s[i - 1], s[i + 1] - s[i])
+    return mask
+
+
+def _check_initial(alignment: dict) -> int:
+    """모서리 0 · R > 500 꼭짓점 0 · 직선 안쪽 R 없음 — 직선 위 꼭짓점 수를 돌려줌."""
+    s, z = _arrays(alignment["base_pvi"])
+    straight = _straight_mask(s, z)
+    curved = {round(float(c["chainage_m"]), 3) for c in alignment["curves"]}
+    for i in range(1, len(s) - 1):
+        key = round(float(s[i]), 3)
+        assert straight[i] != (key in curved), key  # 꺾이면 곡선 · 직선이면 곡선 없음
+    assert not (flat_bends(s, z, L_M) & ~straight).any()  # R > 500 꺾임 없음
+    assert all(float(c["r_m"]) <= 500.0 for c in alignment["curves"])
+    return int(straight.sum())
+
+
+def test_지반_종단_직선화_모서리_없음():
+    alignment = _design(WAVE)
+    assert alignment["policy"]["default_curve_length_m"] == L_M
+    assert "no_curve_keys" not in alignment["policy"]
+    assert _check_initial(alignment) >= 3
+    # 기준이 바뀜을 잼 — 직선화 없이 맞추면 R > 500 꺾임이 남음
+    s, _z = _arrays(alignment["base_pvi"])
+    target = np.array([_wave(v) for v in s])
+    plain = pass_through(s, target, AlignmentPolicy.from_dict(alignment["policy"]))
+    assert flat_bends(s, plain, L_M).sum() >= 3
+
+
+def test_경계가_새로_R_500_넘으면_묶음을_늘림():
+    alignment = _design(GROW)
+    _check_initial(alignment)
+    curved = {round(float(c["chainage_m"]), 3) for c in alignment["curves"]}
+    assert 20.0 not in curved and 40.0 not in curved
+    assert {60.0, 80.0} <= curved
+
+
+def test_손_편집엔_안_걺():
+    alignment = _design(WAVE)
+    s, z = _arrays(alignment["base_pvi"])
+    key = f"{s[np.nonzero(_straight_mask(s, z))[0][0]]:.3f}"
+    edited = build_alignment(
+        base_s=s,
+        base_z=z,
+        chainage=np.array([r["chainage_m"] for r in WAVE["samples"]]),
+        ground=np.array([r["elevation_m"] for r in WAVE["samples"]]),
+        stations=WAVE["stations"],
+        policy=AlignmentPolicy.from_dict(alignment["policy"]),
+        edits={"station_offsets": {key: 0.05}},
+    )
+    curve = next(c for c in edited["curves"] if f"{c['chainage_m']:.3f}" == key)
+    assert curve["r_m"] > 500.0  # 작은 꺾임도 곡선 · 다시 펴지 않음
+
+
+def test_추천_적용_균형_종단도_직선화(tmp_path):
+    from B05_Profile.B05_Profile_Router_RouteInitial import _set_base_pvi
+
+    path = tmp_path / "long.json"
+    path.write_text(json.dumps({**WAVE, "profile_alignment": _design(WAVE)}), encoding="utf-8")
+    plan = [_wave(s) - 0.3 + 0.002 * s for s in WAVE_STATIONS]
+    _set_base_pvi(path, WAVE_STATIONS, plan)
+    stored = json.loads(path.read_text(encoding="utf-8"))["profile_alignment"]
+    s, z = _arrays(stored["base_pvi"])
+    curves, _ = build_curves(s, z, AlignmentPolicy.from_dict(stored["policy"]))
+    _check_initial({**stored, "curves": curves})
+    # 꼭짓점 사이 직선은 균형 종단 상한 안(419-3)
+    limit = np.abs(np.diff(plan) / np.diff(WAVE_STATIONS)).max()
+    assert np.abs(np.diff(z) / np.diff(s)).max() <= limit + 1e-3
+
+
+def test_TS_거울_첫_계획선(tmp_path):
+    cases, expected = [], []
+    for longitudinal in (WAVE, GROW):
+        alignment = _design(longitudinal)
+        cases.append(
+            {
+                "samples": longitudinal["samples"],
+                "stations": [r["chainage_m"] for r in longitudinal["stations"]],
+                "policy": alignment["policy"],
+                "startOffsetM": OPTIONS.start_elevation_offset_m,
+                "endOffsetM": OPTIONS.end_elevation_offset_m,
+            }
+        )
+        expected.append(alignment["base_pvi"])
+    source = tmp_path / "in438.json"
+    source.write_text(json.dumps(cases), encoding="utf-8")
+    proc = subprocess.run(  # noqa: S603 — 고정 실행 파일
+        ["node", str(HERE / "helper_438_1_straighten.cjs"), str(source)],
+        capture_output=True,
+        text=True,
+        encoding="utf-8",
+        check=False,
+    )
+    assert proc.returncode == 0, proc.stderr
+    for got, py in zip(json.loads(proc.stdout), expected, strict=True):
+        assert [n["chainage_m"] for n in got] == [n["chainage_m"] for n in py]
+        assert [n["elevation_m"] for n in got] == pytest.approx(
+            [n["elevation_m"] for n in py], abs=1e-6
+        )
+
+
+def _balanced_427() -> dict:
+    """427 지반 종단을 1 m 내린 판 — 계획선이 지반을 안 지남(균형 종단 꼴)."""
+    data = _long_427()
+    for node in data["profile_alignment"]["base_pvi"]:
+        node["elevation_m"] -= 1.0
+    alignment, profile = rebuild_alignment_profile(data, {})
+    data["profile_alignment"], data["design_profiles"] = alignment, [profile]
+    return data
+
+
+def test_관_옮김_균형_종단은_지금_계획선_높이(tmp_path):
+    first = _balanced_427()
+    stored = copy.deepcopy(first["profile_alignment"])
+    s, z = _arrays(stored["base_pvi"])
+    curves, _ = build_curves(s, z, AlignmentPolicy.from_dict(stored["policy"]))
+    before = float(evaluate(s, z, curves, np.array([MOVED]))[0])
+    _write(tmp_path, first)
+    server = _move(tmp_path, MOVED)["profile_alignment"]
+    row = next(r for r in server["stations"] if r["chainage_m"] == MOVED)
+    assert row["plan_elevation_m"] == pytest.approx(before, abs=1e-4)
+    assert abs(row["plan_elevation_m"] - row["ground_elevation_m"]) > 0.5  # 지반에 안 세움
+    # 화면 짝(`seatBornNodes`) 같은 꼭짓점
+    base = {
+        "basePvi": stored["base_pvi"],
+        "chainage": [r["chainage_m"] for r in stored["samples"]],
+        "ground": [r["ground_elevation_m"] for r in stored["samples"]],
+        "policy": stored["policy"],
+    }
+    [nodes] = _ts(tmp_path, [{"base": base, "gone": [PIPE], "born": [MOVED], "edited": []}])
+    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"], strict=True):
+        assert mine["elevation_m"] == pytest.approx(theirs["elevation_m"], abs=1e-6)
+
+
+def test_부르는_곳():
+    def read(rel: str) -> str:
+        return (ROOT / rel).read_text(encoding="utf-8")
+
+    profile = read("B05_Profile/B05_Profile_Engine_Grade_Profile.py")
+    assert "base_z = straight_pass_through(base_s, base_z, policy)" in profile
+    assert "straight_pass_through(base_s, target, policy, lambda z: _hold(" in read(
+        "B05_Profile/B05_Profile_Engine_RouteInitial_Profile.py"
+    )
+    assert "no_curve_keys" not in read("B05_Profile/B05_Profile_Engine_Grade_Alignment.py")
+    assert "no_curve_keys" not in read("B05_Profile/logic/B05_Profile_UI_Profile_Alignment.ts")