feat(b06,b08): 다단 추가 기슭막이 수량 — 서버 재계산이 선 다단 벽 목록(design.extra_walls)을 남기고 B08 이 줄을 세움 · 높이 안 적은 단은 미확정(④)

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016VBGFXB9AbJBwXP19z75Qq

B06_Section/B06_Section_Server_Calc_Prebuild.py

@@ -245,7 +245,13 @@ async def _recompute(project_id: UUID | str, route_id: int) -> int:
         output = {}
     rows = output.get("areas")
     mass_haul = output.get("mass_haul")
-    if not fixed and not rows and not mass_haul:
+    # 선 다단 벽 목록(④) — 목록째 얹음(수가 아니라 `_AREA_KEYS` 로는 못 거름). 주인 측점엔 빈 목록도.
+    extra_walls = [
+        (float(row["chainage_m"]), {"extra_walls": row["extra_walls"]})
+        for row in output.get("extra_walls") or []
+        if isinstance(row, dict) and isinstance(row.get("extra_walls"), list)
+    ]
+    if not fixed and not rows and not mass_haul and not extra_walls:
         return 0
 
     updated = 0
@@ -281,6 +287,10 @@ async def _recompute(project_id: UUID | str, route_id: int) -> int:
             updated = await merge_cross_section_designs(
                 connection, route_id=route_id, entries=area_entries, replace=False
             )
+            if extra_walls:
+                await merge_cross_section_designs(
+                    connection, route_id=route_id, entries=extra_walls, replace=False
+                )
             if isinstance(mass_haul, dict):
                 await merge_longitudinal_section_data(
                     connection, route_id=route_id, data_patch={"mass_haul": mass_haul}