diff --git a/.tmp_pdf_page2.png b/.tmp_pdf_page2.png
new file mode 100644
index 00000000..64f0f167
Binary files /dev/null and b/.tmp_pdf_page2.png differ
diff --git a/A00_Common/b_asset_cache.ts b/A00_Common/b_asset_cache.ts
index 2b9cc584..2650ddd1 100644
--- a/A00_Common/b_asset_cache.ts
+++ b/A00_Common/b_asset_cache.ts
@@ -10,7 +10,7 @@
  * ========================================================================== */
 
 import { API_BASE_URL } from "@config/config_frontend";
-import { fetchConfirmedSurface } from "../B04_wf1_Surface/B04_wf1_Surface_Api_Fetch";
+import { fetchConfirmedSurface } from "../B04_PreProcess/B04_PreProcess_Api_Fetch";
 
 const DB_NAME = "aislo-asset-cache";
 // 담아 둔 자료의 형식이나 내용이 바뀌면 이 번호를 올린다 — 올리면 기존 보관분을 통째로 버린다.
diff --git a/A00_Common/b_workflow_nav.ts b/A00_Common/b_workflow_nav.ts
index 11c843a5..168c61ac 100644
--- a/A00_Common/b_workflow_nav.ts
+++ b/A00_Common/b_workflow_nav.ts
@@ -5,7 +5,7 @@ import {
   type RoutePath,
 } from "@config/config_frontend";
 import type { WorkflowStage } from "@ui/ui_template_workflow_layout";
-import { fetchConfirmedSurface } from "../B04_wf1_Surface/B04_wf1_Surface_Api_Fetch";
+import { fetchConfirmedSurface } from "../B04_PreProcess/B04_PreProcess_Api_Fetch";
 import { isProjectPreloaded, setPreloadTarget } from "./b_asset_cache";
 import { navigateTo } from "./router";
 
@@ -17,7 +17,7 @@ export interface WorkflowState {
 
 export const WORKFLOW_STEP_ROUTES: readonly RoutePath[] = [
   ROUTES.B03_FILE_INPUT,
-  ROUTES.B04_WF1_SURFACE,
+  ROUTES.B04_PREPROCESS,
   ROUTES.B05_WF2_ROUTE,
   ROUTES.B06_WF3_PROFILE_CROSS,
   ROUTES.B07_WF4_DESIGN_DETAIL,
diff --git a/A00_Common/main.ts b/A00_Common/main.ts
index 5c4b9ed8..f09898c7 100644
--- a/A00_Common/main.ts
+++ b/A00_Common/main.ts
@@ -18,7 +18,7 @@ const FOOTERLESS_ROUTES: readonly RoutePath[] = [
   ROUTES.B01_ACCOUNT,
   ROUTES.B02_PROJ_REGISTER,
   ROUTES.B03_FILE_INPUT,
-  ROUTES.B04_WF1_SURFACE,
+  ROUTES.B04_PREPROCESS,
   ROUTES.B05_WF2_ROUTE,
   ROUTES.B06_WF3_PROFILE_CROSS,
   ROUTES.B07_WF4_DESIGN_DETAIL,
diff --git a/A00_Common/router.ts b/A00_Common/router.ts
index df75959b..de16010c 100644
--- a/A00_Common/router.ts
+++ b/A00_Common/router.ts
@@ -39,8 +39,8 @@ const routeTable: Partial<Record<RoutePath, () => Promise<PageRenderer>>> = {
     (await import("../B02_ProjRegister/B02_ProjRegister_UI_Page")).renderB02ProjRegister,
   [ROUTES.B03_FILE_INPUT]: async () =>
     (await import("../B03_FileInput/B03_FileInput_UI_Page")).renderB03FileInput,
-  [ROUTES.B04_WF1_SURFACE]: async () =>
-    (await import("../B04_wf1_Surface/B04_wf1_Surface_UI_Page")).renderB04Surface,
+  [ROUTES.B04_PREPROCESS]: async () =>
+    (await import("../B04_PreProcess/B04_PreProcess_UI_Page")).renderB04Surface,
   [ROUTES.B05_WF2_ROUTE]: async () =>
     (await import("../B05_wf2_Route/B05_wf2_Route_UI_Page")).renderB05Route,
   [ROUTES.B06_WF3_PROFILE_CROSS]: async () =>
@@ -106,7 +106,7 @@ export async function renderCurrentRoute(outlet: HTMLElement): Promise<void> {
   const workflowRoutes: readonly RoutePath[] = [
     ROUTES.B02_PROJ_REGISTER,
     ROUTES.B03_FILE_INPUT,
-    ROUTES.B04_WF1_SURFACE,
+    ROUTES.B04_PREPROCESS,
     ROUTES.B05_WF2_ROUTE,
     ROUTES.B06_WF3_PROFILE_CROSS,
     ROUTES.B07_WF4_DESIGN_DETAIL,
diff --git a/B03_FileInput/B03_FileInput_Service_Chain.py b/B03_FileInput/B03_FileInput_Service_Chain.py
index ae1dd484..99b70ab8 100644
--- a/B03_FileInput/B03_FileInput_Service_Chain.py
+++ b/B03_FileInput/B03_FileInput_Service_Chain.py
@@ -31,7 +31,7 @@ def _planned_route_points_in_project_crs(project_root: Path) -> list[dict[str, f
     B04 `/planned-route` 조회와 같은 규칙 — CSV가 제 좌표계(crs_epsg)를 적어 두었고
     프로젝트 좌표계와 다르면 한 번 옮긴다.
     """
-    from B04_wf1_Surface.B04_wf1_Surface_Engine_Extent import project_epsg_from_prj
+    from B04_PreProcess.B04_PreProcess_Engine_Extent import project_epsg_from_prj
     from common_util.common_util_route_geometry import (
         find_planned_route_file,
         read_planned_route_csv,
diff --git a/B03_FileInput/B03_FileInput_Service_WF1.py b/B03_FileInput/B03_FileInput_Service_WF1.py
index 976daf86..415479ce 100644
--- a/B03_FileInput/B03_FileInput_Service_WF1.py
+++ b/B03_FileInput/B03_FileInput_Service_WF1.py
@@ -74,7 +74,7 @@ async def trigger_wf1_analysis_and_email(
                 await connection.commit()
             stored_path = await get_project_storage_relative_path(connection, project_id)
             project_info = await _get_project_notification_info(connection, project_id)
-            from B04_wf1_Surface.B04_wf1_Surface_Repository import get_input_file
+            from B04_PreProcess.B04_PreProcess_Repository import get_input_file
 
             input_file = await get_input_file(connection, project_id, input_file_id)
 
@@ -83,9 +83,9 @@ async def trigger_wf1_analysis_and_email(
         if not las_path.is_file():
             raise FileNotFoundError("원본 LAS/LAZ 파일을 찾을 수 없습니다.")
 
-        from B04_wf1_Surface.B04_wf1_Surface_Engine import run_surface_analysis
-        from B04_wf1_Surface.B04_wf1_Surface_Repository import save_surface_analysis_to_db
-        from B04_wf1_Surface.B04_wf1_Surface_Router import write_surface_progress
+        from B04_PreProcess.B04_PreProcess_Engine import run_surface_analysis
+        from B04_PreProcess.B04_PreProcess_Repository import save_surface_analysis_to_db
+        from B04_PreProcess.B04_PreProcess_Router import write_surface_progress
 
         write_surface_progress(project_root, 5, "analyzing", "WF1 분석을 시작합니다.")
 
@@ -119,7 +119,7 @@ async def trigger_wf1_analysis_and_email(
                 # 사용자다. 모두 기본값으로 자동 확정하고 B05·B06 자동 계산 체인까지 탄다.
                 # 관리자는 B04에서 다른 모델을 골라 재확정할 수 있다(체인은 경로가 이미
                 # 있으면 스스로 건너뛴다).
-                from B04_wf1_Surface.B04_wf1_Surface_Service import (
+                from B04_PreProcess.B04_PreProcess_Service import (
                     confirm_surface_selection,
                     find_surface_model_for_selection,
                 )
diff --git a/B03_FileInput/B03_FileInput_UI_Page.ts b/B03_FileInput/B03_FileInput_UI_Page.ts
index 025d2899..1247f1d6 100644
--- a/B03_FileInput/B03_FileInput_UI_Page.ts
+++ b/B03_FileInput/B03_FileInput_UI_Page.ts
@@ -54,7 +54,7 @@ function L(key: keyof typeof ui_locales): string {
 export async function renderB03FileInput(root: HTMLElement): Promise<void> {
   const dashboardUser = await fetchDashboardMe();
   const completionRoute =
-    dashboardUser.role === "SYSTEM_ADMIN" ? ROUTES.B04_WF1_SURFACE : ROUTES.B05_WF2_ROUTE;
+    dashboardUser.role === "SYSTEM_ADMIN" ? ROUTES.B04_PREPROCESS : ROUTES.B05_WF2_ROUTE;
   const slots = initializeSlots();
   const cardMap = new Map<FileSlot, HTMLElement>();
   const resultList = document.createElement("ul");
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Api_Fetch.ts b/B04_PreProcess/B04_PreProcess_Api_Fetch.ts
similarity index 98%
rename from B04_wf1_Surface/B04_wf1_Surface_Api_Fetch.ts
rename to B04_PreProcess/B04_PreProcess_Api_Fetch.ts
index bdc38774..e850db11 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Api_Fetch.ts
+++ b/B04_PreProcess/B04_PreProcess_Api_Fetch.ts
@@ -1,8 +1,8 @@
 /* =============================================================================
- * B04_wf1_Surface_Api_Fetch.ts
+ * B04_PreProcess_Api_Fetch.ts
  * 1차 워크플로우(지표면 분석) API 클라이언트
  *
- * 백엔드 계약 (B04_wf1_Surface_Router.py):
+ * 백엔드 계약 (B04_PreProcess_Router.py):
  *   POST /api/projects/{project_id}/surface/analyze  → 분석 실행 + DB 기록
  *   GET  /api/projects/{project_id}/surface/models    → 모델 목록 조회
  *
@@ -290,7 +290,7 @@ export async function fetchPlannedRoute(projectId: string): Promise<PlannedRoute
   });
 }
 
-/* ── 배수유역 분석 (B04_wf1_Surface_Router_Watershed.py) ────────────────────
+/* ── 배수유역 분석 (B04_PreProcess_Router_Watershed.py) ────────────────────
  * 관리자 확인용. 계획 노선(B03 CSV) + 도엽 등고선·세류선으로 유역을 끝까지 분석하고
  * 결과를 영구저장소에 남긴다. 30초 안팎이 걸리므로 여기서 한 번만 돌린다.
  * ------------------------------------------------------------------------ */
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine.py b/B04_PreProcess/B04_PreProcess_Engine.py
similarity index 94%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine.py
rename to B04_PreProcess/B04_PreProcess_Engine.py
index 83bcd7b1..1e877ce2 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Engine.py
+++ b/B04_PreProcess/B04_PreProcess_Engine.py
@@ -13,13 +13,13 @@ from typing import Any
 
 import numpy as np
 
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Ground import (
+from B04_PreProcess.B04_PreProcess_Engine_Ground import (
     build_ground_masks,
     run_ground_filter,
     summarize_masks,
 )
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Pipeline import build_all_terrain_models
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Structurize import structurize_las
+from B04_PreProcess.B04_PreProcess_Engine_Pipeline import build_all_terrain_models
+from B04_PreProcess.B04_PreProcess_Engine_Structurize import structurize_las
 from common_util.common_util_atomic import atomic_write_npz
 from common_util.common_util_json import atomic_write_json
 from config.config_system import build_surface_model_config
@@ -124,7 +124,7 @@ def run_surface_analysis(
             on_progress(percent, stage, message)
 
     total_started = time.monotonic()
-    stage_root = project_root / "B04_wf1_Surface"
+    stage_root = project_root / "B04_PreProcess"
     processed_dir = stage_root / "processed"
     models_dir = stage_root / "models"
     processed_dir.mkdir(parents=True, exist_ok=True)
@@ -232,13 +232,13 @@ def run_surface_analysis(
         )
         prj_path = prj_candidates[0] if prj_candidates else project_root / "result.prj"
 
-        from B04_wf1_Surface.B04_wf1_Surface_Engine_Extent import (
+        from B04_PreProcess.B04_PreProcess_Engine_Extent import (
             download_extent,
             map_meta_covers,
             satellite_extent,
         )
-        from B04_wf1_Surface.B04_wf1_Surface_Engine_GisVector import download_all_gis_vectors
-        from B04_wf1_Surface.B04_wf1_Surface_Engine_VWorld import (
+        from B04_PreProcess.B04_PreProcess_Engine_GisVector import download_all_gis_vectors
+        from B04_PreProcess.B04_PreProcess_Engine_VWorld import (
             download_vworld_satellite_map,
             get_epsg_from_prj,
         )
@@ -257,7 +257,7 @@ def run_surface_analysis(
         # — 수치지형도 도엽과 같은 눈금. 주변 도엽은 받지 않는다(2026-08-01 사용자 지시).
         map_bounds_for_download = satellite_extent(project_root, las_bounds_dict, project_epsg)
 
-        # VWorld 지도 및 GIS 데이터 저장 위치는 B04_wf1_Surface/processed에 보관.
+        # VWorld 지도 및 GIS 데이터 저장 위치는 B04_PreProcess/processed에 보관.
         layers = [
             {"layer": "Satellite", "ext": "jpeg"},
             {"layer": "Hybrid", "ext": "png"},
@@ -307,9 +307,9 @@ def run_surface_analysis(
         # (실패해도 분석은 계속 — 폴백은 수동 다운로드 + 인제스트)
         _report(92, "download_maps", "수치지형도 도엽 확보 중")
         try:
-            from B04_wf1_Surface.B04_wf1_Surface_Engine_Extent import sheet_reference_points_wgs84
-            from B04_wf1_Surface.B04_wf1_Surface_Engine_MapSheet import neighbors_for_points
-            from B04_wf1_Surface.B04_wf1_Surface_Engine_SheetStore import (
+            from B04_PreProcess.B04_PreProcess_Engine_Extent import sheet_reference_points_wgs84
+            from B04_PreProcess.B04_PreProcess_Engine_MapSheet import neighbors_for_points
+            from B04_PreProcess.B04_PreProcess_Engine_SheetStore import (
                 ensure_sheets,
                 get_project_map_sheets_dir,
                 prune_sheets,
@@ -338,7 +338,7 @@ def run_surface_analysis(
             if sheet_result["available"] and (
                 rebuild or not any(processed_dir.glob("도엽_*.geojson"))
             ):
-                from B04_wf1_Surface.B04_wf1_Surface_Engine_SheetParser import (
+                from B04_PreProcess.B04_PreProcess_Engine_SheetParser import (
                     parse_and_merge_sheets,
                 )
 
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_Contour.py b/B04_PreProcess/B04_PreProcess_Engine_Contour.py
similarity index 100%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_Contour.py
rename to B04_PreProcess/B04_PreProcess_Engine_Contour.py
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_Extent.py b/B04_PreProcess/B04_PreProcess_Engine_Extent.py
similarity index 97%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_Extent.py
rename to B04_PreProcess/B04_PreProcess_Engine_Extent.py
index e84fc474..96dafc18 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Engine_Extent.py
+++ b/B04_PreProcess/B04_PreProcess_Engine_Extent.py
@@ -1,4 +1,4 @@
-# B04_wf1_Surface_Engine_Extent.py
+# B04_PreProcess_Engine_Extent.py
 # 전처리에서 내려받을 범위와 기준 좌표를 정한다.
 #
 # 배경(2026-08-01 사용자 지시): 배경 지도·수치지형도 도엽의 기준을 라이다 범위 한가운데로
@@ -95,7 +95,7 @@ def satellite_extent(
     """
     from pyproj import Transformer
 
-    from .B04_wf1_Surface_Engine_MapSheet import sheet5k_to_bounds, sheets_for_points
+    from .B04_PreProcess_Engine_MapSheet import sheet5k_to_bounds, sheets_for_points
 
     points = sheet_reference_points_wgs84(project_root, las_bounds, target_epsg)
     sheets = sheets_for_points(points)
@@ -145,7 +145,7 @@ def planned_route_bounds(project_root: Path, target_epsg: str) -> dict[str, floa
 
 def project_epsg_from_prj(project_root: Path) -> str:
     """프로젝트 PRJ에서 좌표계를 읽는다. 없으면 중부원점(EPSG:5186)."""
-    from .B04_wf1_Surface_Engine_VWorld import get_epsg_from_prj
+    from .B04_PreProcess_Engine_VWorld import get_epsg_from_prj
 
     for prj_path in sorted(project_root.glob("B03_FileInput/**/*.prj")):
         return get_epsg_from_prj(prj_path.read_text(encoding="utf-8", errors="ignore"))
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_Filter_CSF.py b/B04_PreProcess/B04_PreProcess_Engine_Filter_CSF.py
similarity index 100%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_Filter_CSF.py
rename to B04_PreProcess/B04_PreProcess_Engine_Filter_CSF.py
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_Filter_Grid.py b/B04_PreProcess/B04_PreProcess_Engine_Filter_Grid.py
similarity index 100%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_Filter_Grid.py
rename to B04_PreProcess/B04_PreProcess_Engine_Filter_Grid.py
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_Filter_PMF.py b/B04_PreProcess/B04_PreProcess_Engine_Filter_PMF.py
similarity index 100%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_Filter_PMF.py
rename to B04_PreProcess/B04_PreProcess_Engine_Filter_PMF.py
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_Filter_RANSAC.py b/B04_PreProcess/B04_PreProcess_Engine_Filter_RANSAC.py
similarity index 100%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_Filter_RANSAC.py
rename to B04_PreProcess/B04_PreProcess_Engine_Filter_RANSAC.py
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_GisVector.py b/B04_PreProcess/B04_PreProcess_Engine_GisVector.py
similarity index 98%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_GisVector.py
rename to B04_PreProcess/B04_PreProcess_Engine_GisVector.py
index 3e24eff4..9232893c 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Engine_GisVector.py
+++ b/B04_PreProcess/B04_PreProcess_Engine_GisVector.py
@@ -22,7 +22,7 @@ except ImportError:
     VWORLD_API_KEY = "3DBD7306-7DBD-38BB-B292-267C5ED7AC6B"
     PROJECT_ROOT = Path(__file__).resolve().parent.parent
 
-from B04_wf1_Surface.B04_wf1_Surface_Engine_VWorld import get_epsg_from_prj
+from B04_PreProcess.B04_PreProcess_Engine_VWorld import get_epsg_from_prj
 
 logger = logging.getLogger(__name__)
 
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_Ground.py b/B04_PreProcess/B04_PreProcess_Engine_Ground.py
similarity index 86%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_Ground.py
rename to B04_PreProcess/B04_PreProcess_Engine_Ground.py
index e8484b62..041e0553 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Engine_Ground.py
+++ b/B04_PreProcess/B04_PreProcess_Engine_Ground.py
@@ -9,10 +9,10 @@ from typing import Any
 
 import numpy as np
 
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Filter_CSF import filter_csf
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Filter_Grid import filter_grid_min_z
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Filter_PMF import filter_pmf
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Filter_RANSAC import filter_ransac
+from B04_PreProcess.B04_PreProcess_Engine_Filter_CSF import filter_csf
+from B04_PreProcess.B04_PreProcess_Engine_Filter_Grid import filter_grid_min_z
+from B04_PreProcess.B04_PreProcess_Engine_Filter_PMF import filter_pmf
+from B04_PreProcess.B04_PreProcess_Engine_Filter_RANSAC import filter_ransac
 
 # 필터 키 → 함수 매핑
 _FILTERS = {
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_MapSheet.py b/B04_PreProcess/B04_PreProcess_Engine_MapSheet.py
similarity index 99%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_MapSheet.py
rename to B04_PreProcess/B04_PreProcess_Engine_MapSheet.py
index aae948ad..111f8ebf 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Engine_MapSheet.py
+++ b/B04_PreProcess/B04_PreProcess_Engine_MapSheet.py
@@ -1,4 +1,4 @@
-# B04_wf1_Surface_Engine_MapSheet.py
+# B04_PreProcess_Engine_MapSheet.py
 # 1:5,000 수치지형도 도엽번호 산출 엔진.
 # 국토지리정보원 도엽번호 체계:
 #   - 경위도 1°x1° 구획: 위도 2자리 + 경도 끝 1자리 (예: 369 = 위도 36~37°, 경도 129~130°)
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_ModelBuild.py b/B04_PreProcess/B04_PreProcess_Engine_ModelBuild.py
similarity index 99%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_ModelBuild.py
rename to B04_PreProcess/B04_PreProcess_Engine_ModelBuild.py
index c89cf666..09f032c8 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Engine_ModelBuild.py
+++ b/B04_PreProcess/B04_PreProcess_Engine_ModelBuild.py
@@ -11,7 +11,7 @@ import numpy as np
 from scipy.interpolate import RBFInterpolator, RectBivariateSpline
 from scipy.spatial import Delaunay
 
-from B04_wf1_Surface.B04_wf1_Surface_Engine_ModelContext import (
+from B04_PreProcess.B04_PreProcess_Engine_ModelContext import (
     ProgressCallback,
     TerrainContext,
     artifact_size,
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_ModelContext.py b/B04_PreProcess/B04_PreProcess_Engine_ModelContext.py
similarity index 100%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_ModelContext.py
rename to B04_PreProcess/B04_PreProcess_Engine_ModelContext.py
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_MvtHelper.py b/B04_PreProcess/B04_PreProcess_Engine_MvtHelper.py
similarity index 100%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_MvtHelper.py
rename to B04_PreProcess/B04_PreProcess_Engine_MvtHelper.py
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_Pipeline.py b/B04_PreProcess/B04_PreProcess_Engine_Pipeline.py
similarity index 98%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_Pipeline.py
rename to B04_PreProcess/B04_PreProcess_Engine_Pipeline.py
index a331b32d..8fb66c93 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Engine_Pipeline.py
+++ b/B04_PreProcess/B04_PreProcess_Engine_Pipeline.py
@@ -14,18 +14,18 @@ from typing import Any, Callable
 
 import numpy as np
 
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Contour import (
+from B04_PreProcess.B04_PreProcess_Engine_Contour import (
     CONTOUR_EXTRACTOR_VERSION,
     extract_contours,
 )
-from B04_wf1_Surface.B04_wf1_Surface_Engine_ModelBuild import BUILDERS
-from B04_wf1_Surface.B04_wf1_Surface_Engine_ModelContext import (
+from B04_PreProcess.B04_PreProcess_Engine_ModelBuild import BUILDERS
+from B04_PreProcess.B04_PreProcess_Engine_ModelContext import (
     MODEL_VERSION,
     TerrainContext,
     bounds_dict,
     config_signature,
 )
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Smooth import (
+from B04_PreProcess.B04_PreProcess_Engine_Smooth import (
     compute_smoothing_signature,
     run_smoothing,
 )
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_SheetParser.py b/B04_PreProcess/B04_PreProcess_Engine_SheetParser.py
similarity index 97%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_SheetParser.py
rename to B04_PreProcess/B04_PreProcess_Engine_SheetParser.py
index 81d61437..ff575eee 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Engine_SheetParser.py
+++ b/B04_PreProcess/B04_PreProcess_Engine_SheetParser.py
@@ -1,4 +1,4 @@
-# B04_wf1_Surface_Engine_SheetParser.py
+# B04_PreProcess_Engine_SheetParser.py
 # 1:5,000 수치지형도 도엽 zip 파서 + 9매 병합 → 레이어별 GeoJSON 산출.
 #
 # 레이어 코드 (보유 도엽 2매 실측 확정, 2026-07-26):
@@ -19,7 +19,7 @@ from pathlib import Path
 import geopandas as gpd
 import pandas as pd
 
-from .B04_wf1_Surface_Engine_SheetStore import _load_index, get_sheet_path
+from .B04_PreProcess_Engine_SheetStore import _load_index, get_sheet_path
 
 logger = logging.getLogger(__name__)
 
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_SheetStore.py b/B04_PreProcess/B04_PreProcess_Engine_SheetStore.py
similarity index 97%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_SheetStore.py
rename to B04_PreProcess/B04_PreProcess_Engine_SheetStore.py
index f513143e..58bd99cc 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Engine_SheetStore.py
+++ b/B04_PreProcess/B04_PreProcess_Engine_SheetStore.py
@@ -1,11 +1,11 @@
-# B04_wf1_Surface_Engine_SheetStore.py
+# B04_PreProcess_Engine_SheetStore.py
 # 1:5,000 수치지형도 도엽 zip — 프로젝트 영구저장소 관리.
-# 저장 위치: {프로젝트 저장소}/B04_wf1_Surface/processed/map_sheets/{도엽번호}.zip
+# 저장 위치: {프로젝트 저장소}/B04_PreProcess/processed/map_sheets/{도엽번호}.zip
 # (위성지도·GIS 벡터 등 주변데이터와 동일한 프로젝트 processed 계층)
 #
 # 조사 결과(2026-07-26 실측):
 #   - 도엽번호 산출: 브이월드 오픈 API(api.vworld.kr)에는 색인 레이어가 없어
-#     자체 알고리즘(B04_wf1_Surface_Engine_MapSheet) 사용 — 보유 도엽 10매 정합 확인.
+#     자체 알고리즘(B04_PreProcess_Engine_MapSheet) 사용 — 보유 도엽 10매 정합 확인.
 #   - 도엽 검색: 지도서비스 내부 API `map.vworld.kr/ws3dmap/getDisitalMapList.do`
 #     (type=M02, searchNum=도엽번호, scale, version) — 무로그인 조회 가능.
 #     Ver2.0 = zip(SHP), Ver1.0 = dxf.
@@ -35,7 +35,7 @@ from config.config_system import (
     VWORLD_SESSION_COOKIE,
 )
 
-from .B04_wf1_Surface_Engine_MapSheet import latlon_to_sheet5k, sheet5k_to_bounds
+from .B04_PreProcess_Engine_MapSheet import latlon_to_sheet5k, sheet5k_to_bounds
 
 logger = logging.getLogger(__name__)
 
@@ -61,7 +61,7 @@ def get_project_map_sheets_dir(project_storage_path: str | Path) -> Path:
     project_storage_path: config_system.get_project_storage_path() 결과
     (storage/{회사}/{사용자}/{프로젝트ID}).
     """
-    return Path(project_storage_path) / "B04_wf1_Surface" / "processed" / MAP_SHEETS_DIRNAME
+    return Path(project_storage_path) / "B04_PreProcess" / "processed" / MAP_SHEETS_DIRNAME
 
 
 # ─────────────────────────────────────────────────────────────────────────
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_Smooth.py b/B04_PreProcess/B04_PreProcess_Engine_Smooth.py
similarity index 98%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_Smooth.py
rename to B04_PreProcess/B04_PreProcess_Engine_Smooth.py
index 50af0b91..d06858f3 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Engine_Smooth.py
+++ b/B04_PreProcess/B04_PreProcess_Engine_Smooth.py
@@ -14,7 +14,7 @@ import trimesh
 from scipy import ndimage
 from scipy.interpolate import RectBivariateSpline
 
-from B04_wf1_Surface.B04_wf1_Surface_Engine_ModelContext import (
+from B04_PreProcess.B04_PreProcess_Engine_ModelContext import (
     TerrainContext,
     artifact_size,
     atomic_npz,
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_Structurize.py b/B04_PreProcess/B04_PreProcess_Engine_Structurize.py
similarity index 100%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_Structurize.py
rename to B04_PreProcess/B04_PreProcess_Engine_Structurize.py
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_VWorld.py b/B04_PreProcess/B04_PreProcess_Engine_VWorld.py
similarity index 100%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_VWorld.py
rename to B04_PreProcess/B04_PreProcess_Engine_VWorld.py
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_Watershed_Analyze.py b/B04_PreProcess/B04_PreProcess_Engine_Watershed_Analyze.py
similarity index 98%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_Watershed_Analyze.py
rename to B04_PreProcess/B04_PreProcess_Engine_Watershed_Analyze.py
index f0088617..6534d92d 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Engine_Watershed_Analyze.py
+++ b/B04_PreProcess/B04_PreProcess_Engine_Watershed_Analyze.py
@@ -29,23 +29,23 @@ from typing import Any
 import numpy as np
 from shapely.geometry import LineString
 
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Descent import ContourDescent
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Expand import expand_by_red_boundary
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Flow import (
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Descent import ContourDescent
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Expand import expand_by_red_boundary
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Flow import (
     FlowClassification,
     RoadRaster,
     largest_ring,
     outer_boundary,
     trace_flow,
 )
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Grid import (
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Grid import (
     AZIMUTH_STEPS,
     GridSpec,
     TerrainGrid,
     build_contour_cloud,
     route_elevation_floor,
 )
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Stream import (
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Stream import (
     PrimaryRegion,
     build_primary_region,
 )
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_Watershed_Descent.py b/B04_PreProcess/B04_PreProcess_Engine_Watershed_Descent.py
similarity index 99%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_Watershed_Descent.py
rename to B04_PreProcess/B04_PreProcess_Engine_Watershed_Descent.py
index 98e87368..b0c0331a 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Engine_Watershed_Descent.py
+++ b/B04_PreProcess/B04_PreProcess_Engine_Watershed_Descent.py
@@ -32,7 +32,7 @@ from rasterio.features import rasterize
 from scipy.ndimage import distance_transform_edt
 from shapely.geometry import shape
 
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Grid import (
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Grid import (
     AZIMUTH_INVALID,
     AZIMUTH_SINK,
     AZIMUTH_STEPS,
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_Watershed_Expand.py b/B04_PreProcess/B04_PreProcess_Engine_Watershed_Expand.py
similarity index 97%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_Watershed_Expand.py
rename to B04_PreProcess/B04_PreProcess_Engine_Watershed_Expand.py
index c24d5982..88def1e2 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Engine_Watershed_Expand.py
+++ b/B04_PreProcess/B04_PreProcess_Engine_Watershed_Expand.py
@@ -21,11 +21,11 @@ from typing import Any
 import numpy as np
 from shapely.geometry import LineString
 
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Descent import (
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Descent import (
     ContourDescent,
     build_contour_descent,
 )
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Flow import (
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Flow import (
     FlowClassification,
     RoadRaster,
     burn_stream_flow,
@@ -33,7 +33,7 @@ from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Flow import (
     outermost_cells,
     rasterize_road,
 )
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Grid import GridSpec, TerrainGrid
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Grid import GridSpec, TerrainGrid
 from config.config_system import (
     DRAINAGE_RED_EXPAND_BAND_M,
     DRAINAGE_RED_EXPAND_MAX_ROUNDS,
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_Watershed_Export.py b/B04_PreProcess/B04_PreProcess_Engine_Watershed_Export.py
similarity index 98%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_Watershed_Export.py
rename to B04_PreProcess/B04_PreProcess_Engine_Watershed_Export.py
index 9e4c5e17..9ff75451 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Engine_Watershed_Export.py
+++ b/B04_PreProcess/B04_PreProcess_Engine_Watershed_Export.py
@@ -5,7 +5,7 @@
 `STAGES`에 이름을 하나 더 넣고 `write_stage()`를 호출하면 된다 — 파일명 규칙과 매니페스트
 갱신은 여기서 일괄로 처리한다.
 
-저장 위치: `storage/{회사}/{사용자}/{프로젝트}/B04_wf1_Surface/drainage/`
+저장 위치: `storage/{회사}/{사용자}/{프로젝트}/B04_PreProcess/drainage/`
   - `{단계번호}_{단계이름}.geojson` — WGS84 FeatureCollection, 피처마다 `kind` 속성
   - `manifest.json` — 지금까지 남긴 단계 목록과 요약값
 """
@@ -41,7 +41,7 @@ LonLat = Callable[[float, float], tuple[float, float]]
 
 def drainage_dir(stored_path: str) -> Path:
     return (
-        Path(resolve_stored_project_path(stored_path)) / "B04_wf1_Surface" / DRAINAGE_CACHE_DIRNAME
+        Path(resolve_stored_project_path(stored_path)) / "B04_PreProcess" / DRAINAGE_CACHE_DIRNAME
     )
 
 
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_Watershed_Flow.py b/B04_PreProcess/B04_PreProcess_Engine_Watershed_Flow.py
similarity index 99%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_Watershed_Flow.py
rename to B04_PreProcess/B04_PreProcess_Engine_Watershed_Flow.py
index 0f33e4ef..a03b7521 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Engine_Watershed_Flow.py
+++ b/B04_PreProcess/B04_PreProcess_Engine_Watershed_Flow.py
@@ -24,7 +24,7 @@ from scipy.spatial import cKDTree
 from shapely.geometry import LineString, MultiPolygon, Polygon, shape
 from shapely.ops import unary_union
 
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Grid import (
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Grid import (
     AZIMUTH_STEPS,
     ContourCloud,
     GridSpec,
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_Watershed_Grid.py b/B04_PreProcess/B04_PreProcess_Engine_Watershed_Grid.py
similarity index 100%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_Watershed_Grid.py
rename to B04_PreProcess/B04_PreProcess_Engine_Watershed_Grid.py
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Engine_Watershed_Stream.py b/B04_PreProcess/B04_PreProcess_Engine_Watershed_Stream.py
similarity index 98%
rename from B04_wf1_Surface/B04_wf1_Surface_Engine_Watershed_Stream.py
rename to B04_PreProcess/B04_PreProcess_Engine_Watershed_Stream.py
index cd376ee8..c6951a5f 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Engine_Watershed_Stream.py
+++ b/B04_PreProcess/B04_PreProcess_Engine_Watershed_Stream.py
@@ -5,7 +5,7 @@
 전체**를 잡는다(2026-07-31 사용자 지시).
 
 여기서 정해진 1차 배수유역의 bbox가 곧 격자 해석 범위가 된다.
-표고 해석·격자 생성은 `B04_wf1_Surface_Engine_Watershed_Grid.py`가 맡는다.
+표고 해석·격자 생성은 `B04_PreProcess_Engine_Watershed_Grid.py`가 맡는다.
 """
 
 from __future__ import annotations
@@ -20,7 +20,7 @@ from scipy.spatial import cKDTree
 from shapely.geometry import LineString, MultiPolygon, Polygon, shape
 from shapely.ops import substring, unary_union
 
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Grid import (
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Grid import (
     ContourCloud,
     GridSpec,
     build_cell_mask,
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Repository.py b/B04_PreProcess/B04_PreProcess_Repository.py
similarity index 98%
rename from B04_wf1_Surface/B04_wf1_Surface_Repository.py
rename to B04_PreProcess/B04_PreProcess_Repository.py
index a37f9896..c03583cb 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Repository.py
+++ b/B04_PreProcess/B04_PreProcess_Repository.py
@@ -12,11 +12,11 @@ from uuid import UUID
 
 import aiomysql
 
-_STAGE_ROOT = "B04_wf1_Surface"
+_STAGE_ROOT = "B04_PreProcess"
 
 
 def _validate_stage_path(relative_path: str) -> str:
-    """B04_wf1_Surface 아래의 안전한 상대 경로인지 검증하고 posix 문자열로 반환한다."""
+    """B04_PreProcess 아래의 안전한 상대 경로인지 검증하고 posix 문자열로 반환한다."""
     normalized = PurePosixPath(relative_path.replace("\\", "/"))
     if normalized.is_absolute() or ".." in normalized.parts:
         raise ValueError("DB에는 프로젝트 루트 기준 상대 경로만 저장할 수 있습니다.")
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Router.py b/B04_PreProcess/B04_PreProcess_Router.py
similarity index 98%
rename from B04_wf1_Surface/B04_wf1_Surface_Router.py
rename to B04_PreProcess/B04_PreProcess_Router.py
index 15982ca8..3fc83a85 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Router.py
+++ b/B04_PreProcess/B04_PreProcess_Router.py
@@ -13,23 +13,23 @@ from fastapi import APIRouter, Depends, Request
 from fastapi.responses import JSONResponse, Response
 
 from B03_FileInput.B03_FileInput_Repository import get_project_storage_relative_path
-from B04_wf1_Surface.B04_wf1_Surface_Engine import (
+from B04_PreProcess.B04_PreProcess_Engine import (
     GROUND_POINT_CACHE_VERSION,
     cache_ground_points,
     run_surface_analysis,
 )
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Extent import (
+from B04_PreProcess.B04_PreProcess_Engine_Extent import (
     planned_route_bounds,
     project_epsg_from_prj,
 )
-from B04_wf1_Surface.B04_wf1_Surface_Repository import (
+from B04_PreProcess.B04_PreProcess_Repository import (
     clear_confirmed_surface_models,
     get_input_file,
     list_project_point_cloud_inputs,
     list_surface_models,
     save_surface_analysis_to_db,
 )
-from B04_wf1_Surface.B04_wf1_Surface_Schema import (
+from B04_PreProcess.B04_PreProcess_Schema import (
     SurfaceAnalyzeRequest,
     SurfaceAnalyzeResponse,
     SurfaceConfirmedResponse,
@@ -42,7 +42,7 @@ from B04_wf1_Surface.B04_wf1_Surface_Schema import (
     SurfaceModelSummary,
     SurfacePointCloudSampleResponse,
 )
-from B04_wf1_Surface.B04_wf1_Surface_Service import confirm_surface_selection
+from B04_PreProcess.B04_PreProcess_Service import confirm_surface_selection
 from common_util.common_util_auth import require_system_admin
 from common_util.common_util_http_cache import cached_file_response
 from common_util.common_util_json import atomic_write_json
@@ -62,7 +62,7 @@ logger = logging.getLogger(__name__)
 router = APIRouter(prefix="/api/projects", tags=["B04 Surface Analysis"])
 POINT_CLOUD_SAMPLE_LIMIT = 500_000
 # 분석 진행률 파일: B04 산출 폴더 아래에 원자적으로 기록/조회한다.
-PROGRESS_FILE_RELATIVE = ("B04_wf1_Surface", "processed", "progress.json")
+PROGRESS_FILE_RELATIVE = ("B04_PreProcess", "processed", "progress.json")
 
 
 def _progress_file_path(project_root: Path) -> Path:
@@ -315,7 +315,7 @@ async def get_surface_point_cloud(
         async with pool.acquire() as connection:
             stored_path = await get_project_storage_relative_path(connection, project_id)
         project_root = Path(resolve_stored_project_path(stored_path))
-        structured_path = project_root / "B04_wf1_Surface" / "processed" / "structured.npz"
+        structured_path = project_root / "B04_PreProcess" / "processed" / "structured.npz"
         if not structured_path.is_file():
             return JSONResponse(
                 status_code=404,
@@ -407,7 +407,7 @@ async def get_confirmed_surface(project_id: UUID) -> SurfaceConfirmedResponse |
 
         # 가장자리는 B05가 3D 마커 좌표를 환산할 때 쓰므로, 기존 포인트클라우드 응답과
         # 같은 파일(확정 필터의 지면 포인트)에서 읽어 값이 어긋나지 않게 한다.
-        processed_dir = Path(resolve_stored_project_path(stored_path)) / "B04_wf1_Surface"
+        processed_dir = Path(resolve_stored_project_path(stored_path)) / "B04_PreProcess"
         processed_dir = processed_dir / "processed"
         source_path = processed_dir / "structured.npz"
         if source_filter:
@@ -475,7 +475,7 @@ async def get_surface_ground_stats(project_id: UUID) -> SurfaceGroundStatsRespon
         async with pool.acquire() as connection:
             stored_path = await get_project_storage_relative_path(connection, project_id)
         project_root = Path(resolve_stored_project_path(stored_path))
-        manifest_path = project_root / "B04_wf1_Surface" / "models" / "manifest.json"
+        manifest_path = project_root / "B04_PreProcess" / "models" / "manifest.json"
         if not manifest_path.is_file():
             return SurfaceGroundStatsResponse(project_id=str(project_id), filters={})
         manifest = json.loads(manifest_path.read_text(encoding="utf-8"))
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Router_Basins.py b/B04_PreProcess/B04_PreProcess_Router_Basins.py
similarity index 99%
rename from B04_wf1_Surface/B04_wf1_Surface_Router_Basins.py
rename to B04_PreProcess/B04_PreProcess_Router_Basins.py
index 0d91f71d..d2ceaff9 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Router_Basins.py
+++ b/B04_PreProcess/B04_PreProcess_Router_Basins.py
@@ -22,7 +22,7 @@ from uuid import UUID
 from fastapi import APIRouter
 from fastapi.responses import JSONResponse
 
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Export import drainage_dir
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Export import drainage_dir
 from common_util.common_util_drainage_context import DrainageContext, load_drainage_context
 from common_util.common_util_drainage_detail import DrainageDetail, build_detail
 from common_util.common_util_drainage_pipes import (
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Router_Contour.py b/B04_PreProcess/B04_PreProcess_Router_Contour.py
similarity index 98%
rename from B04_wf1_Surface/B04_wf1_Surface_Router_Contour.py
rename to B04_PreProcess/B04_PreProcess_Router_Contour.py
index 333ef4c1..e1243963 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Router_Contour.py
+++ b/B04_PreProcess/B04_PreProcess_Router_Contour.py
@@ -14,7 +14,7 @@ from fastapi import APIRouter, Request
 from fastapi.responses import JSONResponse, Response
 
 from B03_FileInput.B03_FileInput_Repository import get_project_storage_relative_path
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Contour import (
+from B04_PreProcess.B04_PreProcess_Engine_Contour import (
     CONTOUR_EXTRACTOR_VERSION,
     extract_contours,
 )
@@ -89,7 +89,7 @@ async def get_surface_model_contour(
 
         model_path = project_root / model_file_path
         models_dir = model_path.parent
-        structured_path = project_root / "B04_wf1_Surface" / "processed" / "structured.npz"
+        structured_path = project_root / "B04_PreProcess" / "processed" / "structured.npz"
         stem = model_path.stem
         parts = stem.split("_")
         if len(parts) >= 2:
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Router_GIS.py b/B04_PreProcess/B04_PreProcess_Router_GIS.py
similarity index 95%
rename from B04_wf1_Surface/B04_wf1_Surface_Router_GIS.py
rename to B04_PreProcess/B04_PreProcess_Router_GIS.py
index cbf98838..c93a9a26 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Router_GIS.py
+++ b/B04_PreProcess/B04_PreProcess_Router_GIS.py
@@ -18,7 +18,7 @@ router = APIRouter(prefix="/api/projects", tags=["B04 Surface GIS"])
 tiles_router = APIRouter(tags=["B04 MVT Tiles"])
 
 # 수치지형도 도엽 병합 레이어 (SheetParser 산출과 1:1 — 정의는 SHEET_LAYERS가 유일)
-from B04_wf1_Surface.B04_wf1_Surface_Engine_SheetParser import SHEET_LAYERS  # noqa: E402
+from B04_PreProcess.B04_PreProcess_Engine_SheetParser import SHEET_LAYERS  # noqa: E402
 
 _SHEET_GEOJSON_FILES = {f"도엽_{k}": f"도엽_{k}.geojson" for k in SHEET_LAYERS}
 
@@ -34,7 +34,7 @@ async def get_vworld_meta(
         async with pool.acquire() as connection:
             stored_path = await get_project_storage_relative_path(connection, project_id)
         project_root = Path(resolve_stored_project_path(stored_path))
-        target_dir = project_root / "B04_wf1_Surface" / "processed"
+        target_dir = project_root / "B04_PreProcess" / "processed"
 
         target_layer = "white" if layer_name.lower() in ["gray", "white"] else layer_name.lower()
         meta_name = f"vworld_{target_layer}_meta.json"
@@ -67,7 +67,7 @@ async def get_vworld_map(
         async with pool.acquire() as connection:
             stored_path = await get_project_storage_relative_path(connection, project_id)
         project_root = Path(resolve_stored_project_path(stored_path))
-        target_dir = project_root / "B04_wf1_Surface" / "processed"
+        target_dir = project_root / "B04_PreProcess" / "processed"
 
         target_layer = layer_name.lower()
         if target_layer in ["gray", "white"]:
@@ -107,7 +107,7 @@ async def get_project_geojson(
         async with pool.acquire() as connection:
             stored_path = await get_project_storage_relative_path(connection, project_id)
         project_root = Path(resolve_stored_project_path(stored_path))
-        target_dir = project_root / "B04_wf1_Surface" / "processed"
+        target_dir = project_root / "B04_PreProcess" / "processed"
 
         layer_mapping = {
             "지적도": "연속지적도_bounds.geojson",
@@ -129,7 +129,7 @@ async def get_project_geojson(
 
         # 등고선은 전처리 이후 국가 gpkg가 추가된 경우를 대비해 요청 시점에 크롭 생성한다.
         if layer == "등고선" and not filepath.exists():
-            from B04_wf1_Surface.B04_wf1_Surface_Engine_GisVector import (
+            from B04_PreProcess.B04_PreProcess_Engine_GisVector import (
                 crop_national_contours,
                 read_bounds_wgs84_from_meta,
             )
@@ -185,7 +185,7 @@ async def get_vector_tile(project_id: UUID, layer: str, z: int, x: int, y: int)
         async with pool.acquire() as connection:
             stored_path = await get_project_storage_relative_path(connection, project_id)
         project_root = Path(resolve_stored_project_path(stored_path))
-        target_dir = project_root / "B04_wf1_Surface" / "processed"
+        target_dir = project_root / "B04_PreProcess" / "processed"
 
         layer_mapping = {
             "지적도": "연속지적도_bounds.geojson",
@@ -224,7 +224,7 @@ async def get_vector_tile(project_id: UUID, layer: str, z: int, x: int, y: int)
             return Response(content=empty_tile, media_type="application/x-protobuf")
 
         cache_key = f"{project_id}_{layer}"
-        from B04_wf1_Surface.B04_wf1_Surface_Engine_MvtHelper import generate_mvt_tile
+        from B04_PreProcess.B04_PreProcess_Engine_MvtHelper import generate_mvt_tile
 
         mvt_bytes = generate_mvt_tile(filepath, cache_key, z, x, y, layer_name=layer)
         return Response(
@@ -247,7 +247,7 @@ async def get_planned_route(project_id: UUID) -> dict[str, Any] | JSONResponse:
     B05의 확정 경로가 아니라 **원청이 준 계획선**이다. 아직 올리지 않았거나 좌표가
     모자라면 빈 목록을 돌려준다 — 화면은 계획선만 빼고 그대로 그린다.
     """
-    from B04_wf1_Surface.B04_wf1_Surface_Engine_Extent import project_epsg_from_prj
+    from B04_PreProcess.B04_PreProcess_Engine_Extent import project_epsg_from_prj
     from common_util.common_util_route_geometry import (
         find_planned_route_file,
         read_planned_route_csv,
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Router_Inflow.py b/B04_PreProcess/B04_PreProcess_Router_Inflow.py
similarity index 96%
rename from B04_wf1_Surface/B04_wf1_Surface_Router_Inflow.py
rename to B04_PreProcess/B04_PreProcess_Router_Inflow.py
index 12df7db8..f88ae43a 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Router_Inflow.py
+++ b/B04_PreProcess/B04_PreProcess_Router_Inflow.py
@@ -21,9 +21,9 @@ from fastapi.responses import JSONResponse
 from pyproj import Transformer
 
 from B03_FileInput.B03_FileInput_Repository import get_project_storage_relative_path
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Export import STAGES, drainage_dir
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Flow import polygonize_labels
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Grid import GridSpec
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Export import STAGES, drainage_dir
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Flow import polygonize_labels
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Grid import GridSpec
 from B05_wf2_Route.B05_wf2_Route_Repository import get_surface_crs_epsg
 from common_util.common_util_route_geometry import (
     find_planned_route_file,
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Router_Watershed.py b/B04_PreProcess/B04_PreProcess_Router_Watershed.py
similarity index 98%
rename from B04_wf1_Surface/B04_wf1_Surface_Router_Watershed.py
rename to B04_PreProcess/B04_PreProcess_Router_Watershed.py
index 5ac447c5..378ecb28 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Router_Watershed.py
+++ b/B04_PreProcess/B04_PreProcess_Router_Watershed.py
@@ -1,7 +1,7 @@
 """배수유역 분석 API 라우터 (B04 — 관리자 확인용).
 
 계획 노선(B03 업로드 CSV)과 도엽 등고선·세류선으로 배수유역을 끝까지 분석하고, 결과를
-`storage/{프로젝트}/B04_wf1_Surface/drainage/`에 남긴다. 30초 안팎이 걸리므로 여기서 한 번만
+`storage/{프로젝트}/B04_PreProcess/drainage/`에 남긴다. 30초 안팎이 걸리므로 여기서 한 번만
 돌리고, 일반 사용자가 쓰는 B05는 저장분을 읽어 쓴다(2026-07-31 사용자 지시).
 
 좌표는 사업지 CRS(m)에서 계산하고 응답만 WGS84로 바꿔 내보낸다.
@@ -23,13 +23,13 @@ from pyproj import Transformer
 from shapely.geometry import Point, Polygon, box
 
 from B03_FileInput.B03_FileInput_Repository import get_project_storage_relative_path
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Analyze import preview_stages
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Export import (
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Analyze import preview_stages
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Export import (
     drainage_dir,
     write_grid_arrays,
     write_stage,
 )
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Grid import (
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Grid import (
     AZIMUTH_INVALID,
     AZIMUTH_SINK,
     AZIMUTH_STEPS,
@@ -71,7 +71,7 @@ RESPONSE_SCHEMA_VERSION = 3
 
 
 def _sheet_dir(stored_path: str) -> Path:
-    return Path(resolve_stored_project_path(stored_path)) / "B04_wf1_Surface" / "processed"
+    return Path(resolve_stored_project_path(stored_path)) / "B04_PreProcess" / "processed"
 
 
 def _route_input_dir(stored_path: str) -> Path:
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Schema.py b/B04_PreProcess/B04_PreProcess_Schema.py
similarity index 100%
rename from B04_wf1_Surface/B04_wf1_Surface_Schema.py
rename to B04_PreProcess/B04_PreProcess_Schema.py
diff --git a/B04_wf1_Surface/B04_wf1_Surface_Service.py b/B04_PreProcess/B04_PreProcess_Service.py
similarity index 96%
rename from B04_wf1_Surface/B04_wf1_Surface_Service.py
rename to B04_PreProcess/B04_PreProcess_Service.py
index 2a89dd8f..586d5916 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_Service.py
+++ b/B04_PreProcess/B04_PreProcess_Service.py
@@ -5,7 +5,7 @@ from uuid import UUID
 
 import aiomysql
 
-from B04_wf1_Surface.B04_wf1_Surface_Repository import (
+from B04_PreProcess.B04_PreProcess_Repository import (
     confirm_surface_model,
     list_surface_models,
 )
diff --git a/B04_wf1_Surface/B04_wf1_Surface_UI_Basins.ts b/B04_PreProcess/B04_PreProcess_UI_Basins.ts
similarity index 99%
rename from B04_wf1_Surface/B04_wf1_Surface_UI_Basins.ts
rename to B04_PreProcess/B04_PreProcess_UI_Basins.ts
index 4f9ad460..716806e6 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_UI_Basins.ts
+++ b/B04_PreProcess/B04_PreProcess_UI_Basins.ts
@@ -25,20 +25,20 @@ import {
   type DetailBasin,
   type PipeSource,
   type VWorldMeta,
-} from "./B04_wf1_Surface_Api_Fetch";
+} from "./B04_PreProcess_Api_Fetch";
 import {
   haloColor,
   lonLatToScreen,
   metricToScreen,
   type Normalizer,
   type ViewState,
-} from "./B04_wf1_Surface_UI_MapRender";
+} from "./B04_PreProcess_UI_MapRender";
 import {
   nearestChainage,
   pointAtChainage,
   resampleRoute,
   type RoutePoint,
-} from "./B04_wf1_Surface_UI_RouteSamples";
+} from "./B04_PreProcess_UI_RouteSamples";
 
 function L(key: keyof typeof ui_locales): string {
   return ui_locales[key][currentLanguageIndex];
diff --git a/B04_wf1_Surface/B04_wf1_Surface_UI_Camera.ts b/B04_PreProcess/B04_PreProcess_UI_Camera.ts
similarity index 99%
rename from B04_wf1_Surface/B04_wf1_Surface_UI_Camera.ts
rename to B04_PreProcess/B04_PreProcess_UI_Camera.ts
index 9c0bb402..a59a88b7 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_UI_Camera.ts
+++ b/B04_PreProcess/B04_PreProcess_UI_Camera.ts
@@ -1,6 +1,6 @@
 import * as THREE from "three";
 import type { OrbitControls } from "three/examples/jsm/controls/OrbitControls.js";
-import type { SurfaceBounds } from "./B04_wf1_Surface_Api_Fetch";
+import type { SurfaceBounds } from "./B04_PreProcess_Api_Fetch";
 
 export const SURFACE_CAMERA_FOV = 50;
 const LIGHT_VIEWER_BACKGROUND = 0xf5f7f9;
diff --git a/B04_wf1_Surface/B04_wf1_Surface_UI_FlowArrows.ts b/B04_PreProcess/B04_PreProcess_UI_FlowArrows.ts
similarity index 98%
rename from B04_wf1_Surface/B04_wf1_Surface_UI_FlowArrows.ts
rename to B04_PreProcess/B04_PreProcess_UI_FlowArrows.ts
index d11b67ed..a497ae98 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_UI_FlowArrows.ts
+++ b/B04_PreProcess/B04_PreProcess_UI_FlowArrows.ts
@@ -12,7 +12,7 @@
  * ========================================================================== */
 
 import { themeColor } from "@ui/ui_template_palette";
-import { haloColor } from "./B04_wf1_Surface_UI_MapRender";
+import { haloColor } from "./B04_PreProcess_UI_MapRender";
 
 /** 화살표 1개 — [가로, 세로, 방위(도), 도로 도달, 셀 수]. 앞 두 값의 좌표계는 호출부가 정한다. */
 export type FlowArrow = [number, number, number, boolean, number];
diff --git a/B04_wf1_Surface/B04_wf1_Surface_UI_FlowRamp.ts b/B04_PreProcess/B04_PreProcess_UI_FlowRamp.ts
similarity index 99%
rename from B04_wf1_Surface/B04_wf1_Surface_UI_FlowRamp.ts
rename to B04_PreProcess/B04_PreProcess_UI_FlowRamp.ts
index eebd88e6..fb64a8e9 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_UI_FlowRamp.ts
+++ b/B04_PreProcess/B04_PreProcess_UI_FlowRamp.ts
@@ -11,7 +11,7 @@
 import "@ui/ui_template_flow_legend.css";
 import { currentLanguageIndex, ui_locales } from "@ui/ui_template_locale";
 import { themeColor } from "@ui/ui_template_palette";
-import type { RoutePoint } from "./B04_wf1_Surface_UI_RouteSamples";
+import type { RoutePoint } from "./B04_PreProcess_UI_RouteSamples";
 
 /** 강도 색띠 — 파랑(적음) → 빨강(많음). 정의처는 `ui_template_theme.css`. */
 const RAMP_TOKENS: ReadonlyArray<[name: string, fallback: string]> = [
diff --git a/B04_wf1_Surface/B04_wf1_Surface_UI_FlowStrength.ts b/B04_PreProcess/B04_PreProcess_UI_FlowStrength.ts
similarity index 98%
rename from B04_wf1_Surface/B04_wf1_Surface_UI_FlowStrength.ts
rename to B04_PreProcess/B04_PreProcess_UI_FlowStrength.ts
index f696cf10..80499ab8 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_UI_FlowStrength.ts
+++ b/B04_PreProcess/B04_PreProcess_UI_FlowStrength.ts
@@ -12,22 +12,22 @@
 
 import { currentLanguageIndex, ui_locales } from "@ui/ui_template_locale";
 import { themeColor } from "@ui/ui_template_palette";
-import { fetchRoadInflow, type VWorldMeta } from "./B04_wf1_Surface_Api_Fetch";
+import { fetchRoadInflow, type VWorldMeta } from "./B04_PreProcess_Api_Fetch";
 import {
   haloColor,
   lonLatToScreen,
   metricToScreen,
   type Normalizer,
   type ViewState,
-} from "./B04_wf1_Surface_UI_MapRender";
+} from "./B04_PreProcess_UI_MapRender";
 import {
   buildStrengthArray,
   createFlowLegend,
   drawStrengthLine,
   normalizeStrength,
   rampColor,
-} from "./B04_wf1_Surface_UI_FlowRamp";
-import { pointAtChainage, resampleRoute, type RoutePoint } from "./B04_wf1_Surface_UI_RouteSamples";
+} from "./B04_PreProcess_UI_FlowRamp";
+import { pointAtChainage, resampleRoute, type RoutePoint } from "./B04_PreProcess_UI_RouteSamples";
 
 function L(key: keyof typeof ui_locales): string {
   return ui_locales[key][currentLanguageIndex];
diff --git a/B04_wf1_Surface/B04_wf1_Surface_UI_MapLayers.ts b/B04_PreProcess/B04_PreProcess_UI_MapLayers.ts
similarity index 96%
rename from B04_wf1_Surface/B04_wf1_Surface_UI_MapLayers.ts
rename to B04_PreProcess/B04_PreProcess_UI_MapLayers.ts
index 513763ec..d9d5e0b3 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_UI_MapLayers.ts
+++ b/B04_PreProcess/B04_PreProcess_UI_MapLayers.ts
@@ -2,7 +2,7 @@
  * 2D 지도 레이어 목록·기본값·색 (B04)
  *
  * 어떤 레이어를 다루는지, 처음에 무엇이 켜져 있는지, 무슨 색으로 그리는지만 모은다.
- * 지도 뷰어 본체(`B04_wf1_Surface_UI_MapViewer.ts`)가 700줄 한계에 닿아 분리했다.
+ * 지도 뷰어 본체(`B04_PreProcess_UI_MapViewer.ts`)가 700줄 한계에 닿아 분리했다.
  * 색 값의 정의처는 `ui_template_theme.css`(`--map-*`)이며 여기는 이름만 잇는다.
  * ========================================================================== */
 
diff --git a/B04_wf1_Surface/B04_wf1_Surface_UI_MapOverlays.ts b/B04_PreProcess/B04_PreProcess_UI_MapOverlays.ts
similarity index 96%
rename from B04_wf1_Surface/B04_wf1_Surface_UI_MapOverlays.ts
rename to B04_PreProcess/B04_PreProcess_UI_MapOverlays.ts
index bc78871d..9779fa2d 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_UI_MapOverlays.ts
+++ b/B04_PreProcess/B04_PreProcess_UI_MapOverlays.ts
@@ -2,7 +2,7 @@
  * 2D 지도 오버레이 도형 (B04 지도 · B05 배수유역도 공용)
  *
  * 유역 채움·번호 배지·분수령 파선·상류 세류망처럼 **배경 레이어 위에 얹는** 도형만 모았다.
- * 좌표 변환과 레이어 렌더는 `B04_wf1_Surface_UI_MapRender.ts`가 맡는다 — 그 파일이 700줄
+ * 좌표 변환과 레이어 렌더는 `B04_PreProcess_UI_MapRender.ts`가 맡는다 — 그 파일이 700줄
  * 한계에 닿아 분리했다.
  * ========================================================================== */
 
@@ -15,7 +15,7 @@ import {
   lonLatToScreen,
   type Normalizer,
   type ViewState,
-} from "./B04_wf1_Surface_UI_MapRender";
+} from "./B04_PreProcess_UI_MapRender";
 
 export type FilledRing = {
   ring: ReadonlyArray<readonly [number, number]>;
diff --git a/B04_wf1_Surface/B04_wf1_Surface_UI_MapRender.ts b/B04_PreProcess/B04_PreProcess_UI_MapRender.ts
similarity index 99%
rename from B04_wf1_Surface/B04_wf1_Surface_UI_MapRender.ts
rename to B04_PreProcess/B04_PreProcess_UI_MapRender.ts
index 3349f6ec..9a56bf87 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_UI_MapRender.ts
+++ b/B04_PreProcess/B04_PreProcess_UI_MapRender.ts
@@ -1,5 +1,5 @@
 import { themeColor } from "@ui/ui_template_palette";
-import type { VWorldMeta } from "./B04_wf1_Surface_Api_Fetch";
+import type { VWorldMeta } from "./B04_PreProcess_Api_Fetch";
 
 // 2D 지도 벡터 레이어 렌더 엔진.
 // GeoJSON 좌표를 로드 시 1회만 정규화 맵 좌표(0~1)로 사전 투영해 두고,
diff --git a/B04_wf1_Surface/B04_wf1_Surface_UI_MapViewer.ts b/B04_PreProcess/B04_PreProcess_UI_MapViewer.ts
similarity index 98%
rename from B04_wf1_Surface/B04_wf1_Surface_UI_MapViewer.ts
rename to B04_PreProcess/B04_PreProcess_UI_MapViewer.ts
index a3e75e97..e7403d3f 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_UI_MapViewer.ts
+++ b/B04_PreProcess/B04_PreProcess_UI_MapViewer.ts
@@ -7,9 +7,9 @@ import {
   fetchVWorldMeta,
   getVWorldMapUrl,
   type VWorldMeta,
-} from "./B04_wf1_Surface_Api_Fetch";
-import { niceScaleDistance } from "./B04_wf1_Surface_UI_Camera";
-import { createDetailBasinOverlay } from "./B04_wf1_Surface_UI_Basins";
+} from "./B04_PreProcess_Api_Fetch";
+import { niceScaleDistance } from "./B04_PreProcess_UI_Camera";
+import { createDetailBasinOverlay } from "./B04_PreProcess_UI_Basins";
 import {
   BACKGROUND_DEFAULT_ON,
   BACKGROUND_LAYERS,
@@ -21,9 +21,9 @@ import {
   gisLayerColor,
   type BackgroundLayer,
   type GisLayer,
-} from "./B04_wf1_Surface_UI_MapLayers";
-import { createFlowStrengthOverlay } from "./B04_wf1_Surface_UI_FlowStrength";
-import { createWatershedOverlay } from "./B04_wf1_Surface_UI_Watershed";
+} from "./B04_PreProcess_UI_MapLayers";
+import { createFlowStrengthOverlay } from "./B04_PreProcess_UI_FlowStrength";
+import { createWatershedOverlay } from "./B04_PreProcess_UI_Watershed";
 import {
   computeMapRect,
   computeRouteView,
@@ -40,8 +40,8 @@ import {
   type PlanBounds,
   type PreparedLayer,
   type ViewState,
-} from "./B04_wf1_Surface_UI_MapRender";
-import type { WatershedAnalysis } from "./B04_wf1_Surface_Api_Fetch";
+} from "./B04_PreProcess_UI_MapRender";
+import type { WatershedAnalysis } from "./B04_PreProcess_Api_Fetch";
 
 export interface SurfaceMapViewer {
   root: HTMLElement;
diff --git a/B04_wf1_Surface/B04_wf1_Surface_UI_Page.ts b/B04_PreProcess/B04_PreProcess_UI_Page.ts
similarity index 98%
rename from B04_wf1_Surface/B04_wf1_Surface_UI_Page.ts
rename to B04_PreProcess/B04_PreProcess_UI_Page.ts
index a1af9765..746e84c2 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_UI_Page.ts
+++ b/B04_PreProcess/B04_PreProcess_UI_Page.ts
@@ -29,11 +29,11 @@ import {
   type SurfaceModelSummary,
   type SurfacePointCloudSampleResponse,
   type SurfaceStatusResponse,
-} from "./B04_wf1_Surface_Api_Fetch";
-import { createSurfaceMapViewer } from "./B04_wf1_Surface_UI_MapViewer";
-import { createSurfaceTerrainViewer } from "./B04_wf1_Surface_UI_TerrainViewer";
-import { createSurfacePointCloudViewer } from "./B04_wf1_Surface_UI_Viewer";
-import "./B04_wf1_Surface_UI_Style.css";
+} from "./B04_PreProcess_Api_Fetch";
+import { createSurfaceMapViewer } from "./B04_PreProcess_UI_MapViewer";
+import { createSurfaceTerrainViewer } from "./B04_PreProcess_UI_TerrainViewer";
+import { createSurfacePointCloudViewer } from "./B04_PreProcess_UI_Viewer";
+import "./B04_PreProcess_UI_Style.css";
 
 const SOURCE_FILTERS = ["grid_min_z", "csf", "pmf"] as const;
 const MODEL_METHODS = ["tin", "dtm", "nurbs", "implicit", "meshfree"] as const;
diff --git a/B04_wf1_Surface/B04_wf1_Surface_UI_RouteSamples.ts b/B04_PreProcess/B04_PreProcess_UI_RouteSamples.ts
similarity index 100%
rename from B04_wf1_Surface/B04_wf1_Surface_UI_RouteSamples.ts
rename to B04_PreProcess/B04_PreProcess_UI_RouteSamples.ts
diff --git a/B04_wf1_Surface/B04_wf1_Surface_UI_Style.css b/B04_PreProcess/B04_PreProcess_UI_Style.css
similarity index 99%
rename from B04_wf1_Surface/B04_wf1_Surface_UI_Style.css
rename to B04_PreProcess/B04_PreProcess_UI_Style.css
index 7185ad1f..41a2cdf6 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_UI_Style.css
+++ b/B04_PreProcess/B04_PreProcess_UI_Style.css
@@ -1,5 +1,5 @@
 /* =============================================================================
- * B04_wf1_Surface_UI_Style.css
+ * B04_PreProcess_UI_Style.css
  * 1차 워크플로우(지표면 모델 분석) 페이지 전용 스타일.
  *
  * 원칙(frontend.md §1): 하드코딩 색상 금지. theme.css 변수(var(--...))만 참조.
diff --git a/B04_wf1_Surface/B04_wf1_Surface_UI_TerrainViewer.ts b/B04_PreProcess/B04_PreProcess_UI_TerrainViewer.ts
similarity index 99%
rename from B04_wf1_Surface/B04_wf1_Surface_UI_TerrainViewer.ts
rename to B04_PreProcess/B04_PreProcess_UI_TerrainViewer.ts
index d4812da4..2e621c57 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_UI_TerrainViewer.ts
+++ b/B04_PreProcess/B04_PreProcess_UI_TerrainViewer.ts
@@ -6,7 +6,7 @@ import { API_BASE_URL } from "@config/config_frontend";
 import { fetchCachedBytes, fetchCachedJson } from "../A00_Common/b_asset_cache";
 import { currentLanguageIndex, ui_locales } from "@ui/ui_template_locale";
 import { createProgressCircle } from "@ui/ui_template_progress";
-import type { SurfaceBounds, SurfaceModelSummary } from "./B04_wf1_Surface_Api_Fetch";
+import type { SurfaceBounds, SurfaceModelSummary } from "./B04_PreProcess_Api_Fetch";
 import {
   bindCursorPivotControls,
   bindSurfaceViewerTheme,
@@ -15,7 +15,7 @@ import {
   SURFACE_CAMERA_FOV,
   targetPlaneMetersPerPixel,
   type SurfaceCameraState,
-} from "./B04_wf1_Surface_UI_Camera";
+} from "./B04_PreProcess_UI_Camera";
 
 function L(key: keyof typeof ui_locales): string {
   return ui_locales[key][currentLanguageIndex];
diff --git a/B04_wf1_Surface/B04_wf1_Surface_UI_Viewer.ts b/B04_PreProcess/B04_PreProcess_UI_Viewer.ts
similarity index 98%
rename from B04_wf1_Surface/B04_wf1_Surface_UI_Viewer.ts
rename to B04_PreProcess/B04_PreProcess_UI_Viewer.ts
index 327e1172..ccde0957 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_UI_Viewer.ts
+++ b/B04_PreProcess/B04_PreProcess_UI_Viewer.ts
@@ -3,7 +3,7 @@ import { currentLanguageIndex, ui_locales } from "@ui/ui_template_locale";
 import { createProgressCircle } from "@ui/ui_template_progress";
 import * as THREE from "three";
 import { OrbitControls } from "three/examples/jsm/controls/OrbitControls.js";
-import type { SurfaceBounds, SurfacePointCloudSampleResponse } from "./B04_wf1_Surface_Api_Fetch";
+import type { SurfaceBounds, SurfacePointCloudSampleResponse } from "./B04_PreProcess_Api_Fetch";
 import {
   bindCursorPivotControls,
   bindSurfaceViewerTheme,
@@ -13,9 +13,9 @@ import {
   SURFACE_CAMERA_FOV,
   targetPlaneMetersPerPixel,
   type SurfaceCameraState,
-} from "./B04_wf1_Surface_UI_Camera";
+} from "./B04_PreProcess_UI_Camera";
 
-export type { SurfaceCameraState } from "./B04_wf1_Surface_UI_Camera";
+export type { SurfaceCameraState } from "./B04_PreProcess_UI_Camera";
 
 function L(key: keyof typeof ui_locales): string {
   return ui_locales[key][currentLanguageIndex];
diff --git a/B04_wf1_Surface/B04_wf1_Surface_UI_Watershed.ts b/B04_PreProcess/B04_PreProcess_UI_Watershed.ts
similarity index 99%
rename from B04_wf1_Surface/B04_wf1_Surface_UI_Watershed.ts
rename to B04_PreProcess/B04_PreProcess_UI_Watershed.ts
index d4e29a56..3556fa8c 100644
--- a/B04_wf1_Surface/B04_wf1_Surface_UI_Watershed.ts
+++ b/B04_PreProcess/B04_PreProcess_UI_Watershed.ts
@@ -1,9 +1,9 @@
 import { currentLanguageIndex, ui_locales } from "@ui/ui_template_locale";
 import { themeColor } from "@ui/ui_template_palette";
-import { fetchWatershedAnalysis, type WatershedAnalysis } from "./B04_wf1_Surface_Api_Fetch";
-import { drawFlowArrows } from "./B04_wf1_Surface_UI_FlowArrows";
-import type { Normalizer, ViewState } from "./B04_wf1_Surface_UI_MapRender";
-import { drawUpstreamLines } from "./B04_wf1_Surface_UI_MapOverlays";
+import { fetchWatershedAnalysis, type WatershedAnalysis } from "./B04_PreProcess_Api_Fetch";
+import { drawFlowArrows } from "./B04_PreProcess_UI_FlowArrows";
+import type { Normalizer, ViewState } from "./B04_PreProcess_UI_MapRender";
+import { drawUpstreamLines } from "./B04_PreProcess_UI_MapOverlays";
 
 function L(key: keyof typeof ui_locales): string {
   return ui_locales[key][currentLanguageIndex];
diff --git a/B05_wf2_Route/B05_wf2_Route_Engine_Sections.py b/B05_wf2_Route/B05_wf2_Route_Engine_Sections.py
index 95f72f65..28b0e2b7 100644
--- a/B05_wf2_Route/B05_wf2_Route_Engine_Sections.py
+++ b/B05_wf2_Route/B05_wf2_Route_Engine_Sections.py
@@ -34,7 +34,7 @@ from config.config_system import (
 logger = logging.getLogger(__name__)
 
 _STAGE_SUBDIR = Path("B06_wf3_ProfileCross")
-_MODELS_SUBDIR = Path("B04_wf1_Surface") / "models"
+_MODELS_SUBDIR = Path("B04_PreProcess") / "models"
 
 
 def _load_route_polyline(project_root: Path, route_data_path: str) -> list[list[float]]:
@@ -97,7 +97,7 @@ def _load_pipe_chainages(project_root: Path, polyline: list[list[float]]) -> lis
     """
     path = (
         project_root
-        / "B04_wf1_Surface"
+        / "B04_PreProcess"
         / DRAINAGE_CACHE_DIRNAME
         / DRAINAGE_EDITS_DIRNAME
         / DRAINAGE_PIPE_POINTS_FILENAME
diff --git a/B05_wf2_Route/B05_wf2_Route_Engine_Solver.py b/B05_wf2_Route/B05_wf2_Route_Engine_Solver.py
index f1d03aac..9b7e1dd5 100644
--- a/B05_wf2_Route/B05_wf2_Route_Engine_Solver.py
+++ b/B05_wf2_Route/B05_wf2_Route_Engine_Solver.py
@@ -1,6 +1,6 @@
 """B05 최적 경로 탐색 오케스트레이터.
 
-확정된 지표면 모델(B04_wf1_Surface/models)의 표고를 DTM 격자에 샘플링해
+확정된 지표면 모델(B04_PreProcess/models)의 표고를 DTM 격자에 샘플링해
 비용면을 만들고(캐시 재사용), BP→CP…→EP 다구간 Dijkstra로 최적 경로를
 계산한 뒤 평활·측점·곡률·제약검증 메트릭을 반환한다.
 """
@@ -37,7 +37,7 @@ from config.config_system import (
 )
 
 # B04 지표면 모델 폴더명 (비용면의 표고 원본)
-_MODELS_SUBDIR = Path("B04_wf1_Surface") / "models"
+_MODELS_SUBDIR = Path("B04_PreProcess") / "models"
 # B05 비용면 캐시 폴더명
 _ROUTE_CACHE_SUBDIR = Path("B05_wf2_Route") / "route"
 
diff --git a/B05_wf2_Route/B05_wf2_Route_UI_Drainage_Panel.ts b/B05_wf2_Route/B05_wf2_Route_UI_Drainage_Panel.ts
index c05b6709..cd28024e 100644
--- a/B05_wf2_Route/B05_wf2_Route_UI_Drainage_Panel.ts
+++ b/B05_wf2_Route/B05_wf2_Route_UI_Drainage_Panel.ts
@@ -11,7 +11,7 @@ import {
   type DetailBasinResponse,
   type PipeSource,
   type VWorldMeta,
-} from "../B04_wf1_Surface/B04_wf1_Surface_Api_Fetch";
+} from "../B04_PreProcess/B04_PreProcess_Api_Fetch";
 import {
   computeMapRect,
   createNormalizer,
@@ -22,14 +22,14 @@ import {
   type Normalizer,
   type PreparedLayer,
   type ViewState,
-} from "../B04_wf1_Surface/B04_wf1_Surface_UI_MapRender";
+} from "../B04_PreProcess/B04_PreProcess_UI_MapRender";
 import { type RoutePoint } from "./B05_wf2_Route_Api_Fetch";
-import type { FlowArrow } from "../B04_wf1_Surface/B04_wf1_Surface_UI_FlowArrows";
+import type { FlowArrow } from "../B04_PreProcess/B04_PreProcess_UI_FlowArrows";
 import {
   buildStrengthArray,
   createFlowLegend,
-} from "../B04_wf1_Surface/B04_wf1_Surface_UI_FlowRamp";
-import { resampleRoute } from "../B04_wf1_Surface/B04_wf1_Surface_UI_RouteSamples";
+} from "../B04_PreProcess/B04_PreProcess_UI_FlowRamp";
+import { resampleRoute } from "../B04_PreProcess/B04_PreProcess_UI_RouteSamples";
 import { createPipeEditor } from "./B05_wf2_Route_UI_Drainage_Pipes";
 import { createProgressCircle } from "@ui/ui_template_progress";
 import { createMapContextMenu } from "@ui/ui_template_context_menu";
@@ -61,7 +61,7 @@ const CLICK_SLOP_PX = 4;
 
 // 배수유역도 패널 — 하단 종단 패널 안쪽 우측에 도킹되는 2단 사이드 패널.
 // 하단 패널이 닫히면 이 패널도 함께 화면에서 사라진다(부모 안에 들어 있으므로 자동).
-// 지도는 B04에서 분리한 렌더 엔진(B04_wf1_Surface_UI_MapRender)을 그대로 재사용해
+// 지도는 B04에서 분리한 렌더 엔진(B04_PreProcess_UI_MapRender)을 그대로 재사용해
 // 사전 투영·LOD·뷰포트 컬링·커서 중심 줌 동작을 동일하게 얻는다.
 
 function L(key: keyof typeof ui_locales): string {
diff --git a/B05_wf2_Route/B05_wf2_Route_UI_Drainage_Parts.ts b/B05_wf2_Route/B05_wf2_Route_UI_Drainage_Parts.ts
index fdd9e912..61eecb1d 100644
--- a/B05_wf2_Route/B05_wf2_Route_UI_Drainage_Parts.ts
+++ b/B05_wf2_Route/B05_wf2_Route_UI_Drainage_Parts.ts
@@ -9,16 +9,16 @@
 import { currentLanguageIndex, ui_locales } from "@ui/ui_template_locale";
 import { themeColor } from "@ui/ui_template_palette";
 import { DRAINAGE_SHEET_LAYERS, fetchCachedSheetLayer } from "../A00_Common/b_asset_cache";
-import { fetchVWorldMeta, type VWorldMeta } from "../B04_wf1_Surface/B04_wf1_Surface_Api_Fetch";
+import { fetchVWorldMeta, type VWorldMeta } from "../B04_PreProcess/B04_PreProcess_Api_Fetch";
 import {
   computeMapRect,
   computeRouteView,
   type GeoJsonCollection,
   type ViewState,
-} from "../B04_wf1_Surface/B04_wf1_Surface_UI_MapRender";
-import { normalizeStrength, rampColor } from "../B04_wf1_Surface/B04_wf1_Surface_UI_FlowRamp";
+} from "../B04_PreProcess/B04_PreProcess_UI_MapRender";
+import { normalizeStrength, rampColor } from "../B04_PreProcess/B04_PreProcess_UI_FlowRamp";
 import type { MapContextMenu } from "@ui/ui_template_context_menu";
-import type { DetailBasin } from "../B04_wf1_Surface/B04_wf1_Surface_Api_Fetch";
+import type { DetailBasin } from "../B04_PreProcess/B04_PreProcess_Api_Fetch";
 import type { PipeEditor, PipePoint } from "./B05_wf2_Route_UI_Drainage_Pipes";
 
 function L(key: keyof typeof ui_locales): string {
diff --git a/B05_wf2_Route/B05_wf2_Route_UI_Drainage_Pipes.ts b/B05_wf2_Route/B05_wf2_Route_UI_Drainage_Pipes.ts
index e6080127..fdc07159 100644
--- a/B05_wf2_Route/B05_wf2_Route_UI_Drainage_Pipes.ts
+++ b/B05_wf2_Route/B05_wf2_Route_UI_Drainage_Pipes.ts
@@ -1,6 +1,6 @@
 import { themeColor } from "@ui/ui_template_palette";
-import type { VWorldMeta } from "../B04_wf1_Surface/B04_wf1_Surface_Api_Fetch";
-import type { ViewState } from "../B04_wf1_Surface/B04_wf1_Surface_UI_MapRender";
+import type { VWorldMeta } from "../B04_PreProcess/B04_PreProcess_Api_Fetch";
+import type { ViewState } from "../B04_PreProcess/B04_PreProcess_UI_MapRender";
 
 // 배관(관 매설) 지점 편집기 — 배수유역 패널의 계획선 위 마커 표시·추가·이동·삭제.
 // 마커 위치의 단일 소스는 누가거리(chainage)다. 화면 좌표는 매 프레임 노선
diff --git a/B05_wf2_Route/B05_wf2_Route_UI_Drainage_Render.ts b/B05_wf2_Route/B05_wf2_Route_UI_Drainage_Render.ts
index 3231a8b3..1cef7c93 100644
--- a/B05_wf2_Route/B05_wf2_Route_UI_Drainage_Render.ts
+++ b/B05_wf2_Route/B05_wf2_Route_UI_Drainage_Render.ts
@@ -17,18 +17,18 @@ import {
   type Normalizer,
   type PreparedLayer,
   type ViewState,
-} from "../B04_wf1_Surface/B04_wf1_Surface_UI_MapRender";
+} from "../B04_PreProcess/B04_PreProcess_UI_MapRender";
 import {
   drawFilledRing,
   drawRidgeRing,
   drawRingBadge,
   drawUpstreamLines,
   ringCenterOnScreen,
-} from "../B04_wf1_Surface/B04_wf1_Surface_UI_MapOverlays";
-import type { DetailBasin, VWorldMeta } from "../B04_wf1_Surface/B04_wf1_Surface_Api_Fetch";
-import { drawFlowArrows, type FlowArrow } from "../B04_wf1_Surface/B04_wf1_Surface_UI_FlowArrows";
-import { drawStrengthLine } from "../B04_wf1_Surface/B04_wf1_Surface_UI_FlowRamp";
-import type { RoutePoint } from "../B04_wf1_Surface/B04_wf1_Surface_UI_RouteSamples";
+} from "../B04_PreProcess/B04_PreProcess_UI_MapOverlays";
+import type { DetailBasin, VWorldMeta } from "../B04_PreProcess/B04_PreProcess_Api_Fetch";
+import { drawFlowArrows, type FlowArrow } from "../B04_PreProcess/B04_PreProcess_UI_FlowArrows";
+import { drawStrengthLine } from "../B04_PreProcess/B04_PreProcess_UI_FlowRamp";
+import type { RoutePoint } from "../B04_PreProcess/B04_PreProcess_UI_RouteSamples";
 import {
   basinColor,
   createMetricProjector,
diff --git a/B05_wf2_Route/B05_wf2_Route_UI_Page.ts b/B05_wf2_Route/B05_wf2_Route_UI_Page.ts
index ce7251c2..b7e5961c 100644
--- a/B05_wf2_Route/B05_wf2_Route_UI_Page.ts
+++ b/B05_wf2_Route/B05_wf2_Route_UI_Page.ts
@@ -14,7 +14,7 @@ import {
   fetchConfirmedSurface,
   listSurfaceModels,
   type SurfaceModelSummary,
-} from "../B04_wf1_Surface/B04_wf1_Surface_Api_Fetch";
+} from "../B04_PreProcess/B04_PreProcess_Api_Fetch";
 import {
   confirmRoute,
   fetchLatestRoute,
diff --git a/B05_wf2_Route/B05_wf2_Route_UI_Viewer.ts b/B05_wf2_Route/B05_wf2_Route_UI_Viewer.ts
index 3e19c285..1cf617c1 100644
--- a/B05_wf2_Route/B05_wf2_Route_UI_Viewer.ts
+++ b/B05_wf2_Route/B05_wf2_Route_UI_Viewer.ts
@@ -4,7 +4,7 @@ import { GLTFLoader } from "three/examples/jsm/loaders/GLTFLoader.js";
 import { PLYLoader } from "three/examples/jsm/loaders/PLYLoader.js";
 import { API_BASE_URL } from "@config/config_frontend";
 import { fetchCachedBytes, fetchCachedJson } from "../A00_Common/b_asset_cache";
-import { bindCursorPivotControls } from "../B04_wf1_Surface/B04_wf1_Surface_UI_Camera";
+import { bindCursorPivotControls } from "../B04_PreProcess/B04_PreProcess_UI_Camera";
 import {
   createRouteMarkers,
   sceneToModel,
diff --git a/common_util/common_util_drainage_context.py b/common_util/common_util_drainage_context.py
index fe48a4b0..743d9b59 100644
--- a/common_util/common_util_drainage_context.py
+++ b/common_util/common_util_drainage_context.py
@@ -42,7 +42,7 @@ from config.config_db import get_db_pool
 logger = logging.getLogger(__name__)
 
 _INPUT_SUBDIR = Path("B03_FileInput") / "input"
-_MODELS_SUBDIR = Path("B04_wf1_Surface") / "models"
+_MODELS_SUBDIR = Path("B04_PreProcess") / "models"
 
 
 @dataclass
diff --git a/common_util/common_util_drainage_detail.py b/common_util/common_util_drainage_detail.py
index 326126d2..e86852a8 100644
--- a/common_util/common_util_drainage_detail.py
+++ b/common_util/common_util_drainage_detail.py
@@ -32,10 +32,10 @@ from typing import Any
 
 import numpy as np
 
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Analyze import find_inflow_hotspots
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Export import STAGES
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Flow import largest_ring, polygonize_labels
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Grid import GridSpec
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Analyze import find_inflow_hotspots
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Export import STAGES
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Flow import largest_ring, polygonize_labels
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Grid import GridSpec
 from common_util.common_util_route_geometry import (
     RouteVertex,
     StructureCandidate,
diff --git a/common_util/common_util_drainage_pipes.py b/common_util/common_util_drainage_pipes.py
index 18f579ba..b126f599 100644
--- a/common_util/common_util_drainage_pipes.py
+++ b/common_util/common_util_drainage_pipes.py
@@ -19,7 +19,7 @@ from dataclasses import dataclass
 from pathlib import Path
 from typing import Any
 
-from B04_wf1_Surface.B04_wf1_Surface_Engine_Watershed_Export import drainage_dir
+from B04_PreProcess.B04_PreProcess_Engine_Watershed_Export import drainage_dir
 from common_util.common_util_json import atomic_write_json
 from common_util.common_util_route_geometry import RouteVertex
 from config.config_system import (
diff --git a/common_util/common_util_storage.py b/common_util/common_util_storage.py
index 0b72910b..b2b85eba 100644
--- a/common_util/common_util_storage.py
+++ b/common_util/common_util_storage.py
@@ -7,8 +7,8 @@ from config.config_system import PROJECT_STORAGE_STAGE_DIRS, STORAGE_BASE_DIR
 
 PROJECT_STORAGE_LAYOUT_V2 = (
     ("B03_FileInput", "input"),
-    ("B04_wf1_Surface", "processed"),
-    ("B04_wf1_Surface", "models"),
+    ("B04_PreProcess", "processed"),
+    ("B04_PreProcess", "models"),
     ("B05_wf2_Route", "route"),
     ("B06_wf3_ProfileCross", "longitudinal"),
     ("B06_wf3_ProfileCross", "cross_sections"),
diff --git a/common_util/common_util_surface_sampler.py b/common_util/common_util_surface_sampler.py
index 00306d41..597243f2 100644
--- a/common_util/common_util_surface_sampler.py
+++ b/common_util/common_util_surface_sampler.py
@@ -1,7 +1,7 @@
 """확정 지표면 모델 표고 sampler (공용).
 
 종·횡단 생성기가 의존하는 최소 표고 조회 인터페이스와, 확정된 지표면 모델
-(B04_wf1_Surface/models)을 일괄 XY 표고 sampler로 여는 팩토리를 제공한다.
+(B04_PreProcess/models)을 일괄 XY 표고 sampler로 여는 팩토리를 제공한다.
 DTM valid_mask를 footprint로 결합해 데이터가 없는 영역을 임의 표고로 메우지
 않는다.
 
diff --git a/config/config_frontend.ts b/config/config_frontend.ts
index 48de7323..508cf0d4 100644
--- a/config/config_frontend.ts
+++ b/config/config_frontend.ts
@@ -84,7 +84,7 @@ export const ROUTES = {
   B01_ACCOUNT: "b01-account",
   B02_PROJ_REGISTER: "b02-proj-register",
   B03_FILE_INPUT: "b03-file-input",
-  B04_WF1_SURFACE: "b04-wf1-surface",
+  B04_PREPROCESS: "b04-preprocess",
   B05_WF2_ROUTE: "b05-wf2-route",
   B06_WF3_PROFILE_CROSS: "b06-wf3-profile-cross",
   B07_WF4_DESIGN_DETAIL: "b07-wf4-design-detail",
@@ -107,7 +107,7 @@ export const PROTECTED_ROUTES: readonly RoutePath[] = [
   ROUTES.B01_ACCOUNT,
   ROUTES.B02_PROJ_REGISTER,
   ROUTES.B03_FILE_INPUT,
-  ROUTES.B04_WF1_SURFACE,
+  ROUTES.B04_PREPROCESS,
   ROUTES.B05_WF2_ROUTE,
   ROUTES.B06_WF3_PROFILE_CROSS,
   ROUTES.B07_WF4_DESIGN_DETAIL,
diff --git a/config/config_system.py b/config/config_system.py
index 947c604d..6a16d8e0 100644
--- a/config/config_system.py
+++ b/config/config_system.py
@@ -289,7 +289,7 @@ DRAINAGE_DITCH_SAMPLE_M = float(os.getenv("DRAINAGE_DITCH_SAMPLE_M", "1.0"))
 DRAINAGE_POLYGON_SIMPLIFY_M = float(os.getenv("DRAINAGE_POLYGON_SIMPLIFY_M", "2.0"))
 # 이 면적(㎡) 미만의 유역 조각은 버린다(격자 노이즈 제거).
 DRAINAGE_MIN_BASIN_AREA_M2 = float(os.getenv("DRAINAGE_MIN_BASIN_AREA_M2", "100.0"))
-# 격자 해석 결과 캐시 파일명. 프로젝트 저장소의 B04_wf1_Surface/drainage/ 아래에 놓인다.
+# 격자 해석 결과 캐시 파일명. 프로젝트 저장소의 B04_PreProcess/drainage/ 아래에 놓인다.
 DRAINAGE_CACHE_DIRNAME = "drainage"
 DRAINAGE_CACHE_FILENAME = "watershed_grid.npz"
 # 분석 응답 자체를 그대로 담아 두는 파일. 재산정하지 않는 한 이걸 그대로 돌려준다 —
@@ -660,7 +660,7 @@ FOREST_ROAD_PROFILE_ALIGNMENT = {
 STORAGE_BASE_DIR = os.path.join(os.path.dirname(os.path.dirname(__file__)), "storage")
 
 # 1:5,000 수치지형도 도엽 저장 폴더명 — 프로젝트 영구저장소 하위
-# (storage/{회사}/{사용자}/{프로젝트ID}/B04_wf1_Surface/processed/map_sheets/)
+# (storage/{회사}/{사용자}/{프로젝트ID}/B04_PreProcess/processed/map_sheets/)
 MAP_SHEETS_DIRNAME = "map_sheets"
 MAP_SHEETS_INDEX_FILENAME = "map_sheets_index.json"
 
@@ -687,7 +687,7 @@ RESOURCE_LOG_RETENTION_DAYS = 30  # 로그 보관: 1개월
 PROJECT_STORAGE_STAGE_DIRS = frozenset(
     {
         "B03_FileInput",
-        "B04_wf1_Surface",
+        "B04_PreProcess",
         "B05_wf2_Route",
         "B06_wf3_ProfileCross",
         "B07_wf4_DesignDetail",
diff --git a/db_management/001_create_schema.sql b/db_management/001_create_schema.sql
index 0d2c6401..eba4f90d 100644
--- a/db_management/001_create_schema.sql
+++ b/db_management/001_create_schema.sql
@@ -227,9 +227,9 @@ CREATE TABLE IF NOT EXISTS processed_point_cloud (
   input_file_id INT NOT NULL,               -- FK는 later
   project_id CHAR(36) NOT NULL,             -- FK는 later
   process_type VARCHAR(50),                 -- filtered, sampled, classified
-  processed_file_path VARCHAR(500),         -- storage/.../B04_wf1_Surface/processed/...
+  processed_file_path VARCHAR(500),         -- storage/.../B04_PreProcess/processed/...
   converted_format VARCHAR(50),             -- ply, laz, las 등
-  converted_file_path VARCHAR(500),         -- storage/.../B04_wf1_Surface/processed/...
+  converted_file_path VARCHAR(500),         -- storage/.../B04_PreProcess/processed/...
   point_count INT,
   min_z FLOAT,
   max_z FLOAT,
@@ -258,7 +258,7 @@ CREATE TABLE IF NOT EXISTS surface_models (
   status VARCHAR(50) DEFAULT 'PROCESSING',  -- PROCESSING, COMPLETE, CONFIRMED, FAILED
   crs_epsg INT,
   resolution_m FLOAT,
-  model_file_path VARCHAR(500),             -- storage/.../B04_wf1_Surface/models/...
+  model_file_path VARCHAR(500),             -- storage/.../B04_PreProcess/models/...
   generation_params JSON,                   -- filter_type, algorithm, params
   created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
   completed_at TIMESTAMP NULL DEFAULT NULL
@@ -270,7 +270,7 @@ CREATE TABLE IF NOT EXISTS terrain_layers (
   surface_model_id INT NOT NULL,            -- FK는 later
   layer_name VARCHAR(100),                  -- 지표, 제1층, 제2층
   geometry_type VARCHAR(50),                -- POINTCLOUD, GRID, MESH, CONTOUR
-  layer_file_path VARCHAR(500),             -- storage/.../B04_wf1_Surface/models/...
+  layer_file_path VARCHAR(500),             -- storage/.../B04_PreProcess/models/...
   file_format VARCHAR(50),                  -- geojson, geotiff, ply, obj
   file_size_mb FLOAT,
   statistics JSON,                          -- min_z, max_z, mean_slope, point_count
diff --git a/main.py b/main.py
index 64c6178d..52df8aea 100644
--- a/main.py
+++ b/main.py
@@ -28,13 +28,13 @@ from A09_Security.A09_Security_Router import router as a09_security_router
 from B01_Dashboard.B01_Dashboard_Router import router as b01_dashboard_router
 from B02_ProjRegister.B02_ProjRegister_Router import router as b02_proj_register_router
 from B03_FileInput.B03_FileInput_Router import router as b03_file_input_router
-from B04_wf1_Surface.B04_wf1_Surface_Router import router as b04_surface_router
-from B04_wf1_Surface.B04_wf1_Surface_Router_Basins import router as b04_basins_router
-from B04_wf1_Surface.B04_wf1_Surface_Router_Contour import router as b04_surface_contour_router
-from B04_wf1_Surface.B04_wf1_Surface_Router_GIS import router as b04_surface_gis_router
-from B04_wf1_Surface.B04_wf1_Surface_Router_GIS import tiles_router
-from B04_wf1_Surface.B04_wf1_Surface_Router_Inflow import router as b04_inflow_router
-from B04_wf1_Surface.B04_wf1_Surface_Router_Watershed import router as b04_watershed_router
+from B04_PreProcess.B04_PreProcess_Router import router as b04_surface_router
+from B04_PreProcess.B04_PreProcess_Router_Basins import router as b04_basins_router
+from B04_PreProcess.B04_PreProcess_Router_Contour import router as b04_surface_contour_router
+from B04_PreProcess.B04_PreProcess_Router_GIS import router as b04_surface_gis_router
+from B04_PreProcess.B04_PreProcess_Router_GIS import tiles_router
+from B04_PreProcess.B04_PreProcess_Router_Inflow import router as b04_inflow_router
+from B04_PreProcess.B04_PreProcess_Router_Watershed import router as b04_watershed_router
 from B05_wf2_Route.B05_wf2_Route_Router import router as b05_route_router
 from B06_wf3_ProfileCross.B06_wf3_ProfileCross_Router import router as b06_section_router
 from B06_wf3_ProfileCross.B06_wf3_ProfileCross_Router_Confirm import (
diff --git a/scratch/test_mapsheet_verification.py b/scratch/test_mapsheet_verification.py
index be8f1978..c896a51e 100644
--- a/scratch/test_mapsheet_verification.py
+++ b/scratch/test_mapsheet_verification.py
@@ -16,7 +16,7 @@ sys.path.insert(0, str(PROJECT_ROOT))
 
 import geopandas as gpd
 
-from B04_wf1_Surface.B04_wf1_Surface_Engine_MapSheet import (
+from B04_PreProcess.B04_PreProcess_Engine_MapSheet import (
     latlon_to_sheet5k,
     neighbors_3x3,
     sheet5k_center,
diff --git a/scratch/test_sheetstore_ingest.py b/scratch/test_sheetstore_ingest.py
index 35bd8616..393951db 100644
--- a/scratch/test_sheetstore_ingest.py
+++ b/scratch/test_sheetstore_ingest.py
@@ -1,6 +1,6 @@
 """도엽 프로젝트 영구저장소(SheetStore) 실테스트.
 
-- 저장 위치: {프로젝트 저장소}/B04_wf1_Surface/processed/map_sheets/
+- 저장 위치: {프로젝트 저장소}/B04_PreProcess/processed/map_sheets/
 - ensure_sheets: 보유 도엽은 즉시 반환, 미보유는 자동 다운로드(세션 만료 시 자동 재로그인)
 """
 
@@ -10,8 +10,8 @@ from pathlib import Path
 PROJECT_ROOT = Path(__file__).resolve().parent.parent
 sys.path.insert(0, str(PROJECT_ROOT))
 
-from B04_wf1_Surface.B04_wf1_Surface_Engine_MapSheet import neighbors_3x3
-from B04_wf1_Surface.B04_wf1_Surface_Engine_SheetStore import (
+from B04_PreProcess.B04_PreProcess_Engine_MapSheet import neighbors_3x3
+from B04_PreProcess.B04_PreProcess_Engine_SheetStore import (
     ensure_sheets,
     get_project_map_sheets_dir,
     get_sheet_path,
diff --git a/scratch/test_vworld_download.py b/scratch/test_vworld_download.py
index 33c78b47..83d4cb43 100644
--- a/scratch/test_vworld_download.py
+++ b/scratch/test_vworld_download.py
@@ -7,12 +7,12 @@ import numpy as np
 PROJECT_ROOT = Path(__file__).resolve().parent.parent
 sys.path.insert(0, str(PROJECT_ROOT))
 
-from B04_wf1_Surface.B04_wf1_Surface_Engine_VWorld import download_vworld_satellite_map
-from B04_wf1_Surface.B04_wf1_Surface_Engine_GisVector import download_all_gis_vectors
+from B04_PreProcess.B04_PreProcess_Engine_VWorld import download_vworld_satellite_map
+from B04_PreProcess.B04_PreProcess_Engine_GisVector import download_all_gis_vectors
 
 PRJ_PATH = PROJECT_ROOT / "storage/1/3/acb9170b-9ac8-49b3-82a0-51cfa32bb42d/B03_FileInput/input/prj/result.prj"
-NPZ_PATH = PROJECT_ROOT / "storage/1/3/acb9170b-9ac8-49b3-82a0-51cfa32bb42d/B04_wf1_Surface/processed/ground_points_csf.npz"
-OUTPUT_DIR = PROJECT_ROOT / "storage/1/3/acb9170b-9ac8-49b3-82a0-51cfa32bb42d/B04_wf1_Surface/processed"
+NPZ_PATH = PROJECT_ROOT / "storage/1/3/acb9170b-9ac8-49b3-82a0-51cfa32bb42d/B04_PreProcess/processed/ground_points_csf.npz"
+OUTPUT_DIR = PROJECT_ROOT / "storage/1/3/acb9170b-9ac8-49b3-82a0-51cfa32bb42d/B04_PreProcess/processed"
 
 def main():
     print("Loading NPZ to get bounds...")
diff --git a/ui_template/ui_template_locale_b1.ts b/ui_template/ui_template_locale_b1.ts
index 397cd933..412cc361 100644
--- a/ui_template/ui_template_locale_b1.ts
+++ b/ui_template/ui_template_locale_b1.ts
@@ -1,6 +1,6 @@
 /* =============================================================================
  * ui_template_locale_b1.ts
- * 다국어 사전 — B 그룹 전반부 (B01_Dashboard ~ B04_wf1_Surface)
+ * 다국어 사전 — B 그룹 전반부 (B01_Dashboard ~ B04_PreProcess)
  *
  * 워크플로우 진행 단계 라벨은 ui_template_locale_common.ts 의 WF_Step_* 키를
  * 재사용한다 (중복 등록 방지).
@@ -265,7 +265,7 @@ export const ui_locales_b1 = {
     "Background upload is unavailable in this browser.",
   ],
 
-  /* --- B04_wf1_Surface 지표면 모델 분석 --- */
+  /* --- B04_PreProcess 지표면 모델 분석 --- */
   B04_Surface_Title: ["전처리", "Preprocess"],
   B04_Surface_Field_InputId: ["입력 파일 ID", "Input File ID"],
   B04_Surface_Field_InputId_Placeholder: ["예: 1", "e.g. 1"],