diff --git a/D03_PlanAnalysis/D03_PlanAnalysis_Router.py b/D03_PlanAnalysis/D03_PlanAnalysis_Router.py
index 32419a7f7..c5628f21b 100644
--- a/D03_PlanAnalysis/D03_PlanAnalysis_Router.py
+++ b/D03_PlanAnalysis/D03_PlanAnalysis_Router.py
@@ -3,7 +3,7 @@
 - `GET /api/projects/{id}/plan/terrain/extent` — 받기 전 범위(상자 · 도엽 · 칸 수 · 받은 범위)
 - `POST …/plan/terrain` — 사업 전체 지형 한 벌 받기(뒤에서 · 누를 때만) · 끝나면 `surface_models` 행
 - `GET …/plan/progress` — 일의 진행률
-- `GET …/plan/tile/{z}/{x}/{y}` — 위성 조각 대리(586-1 GL 바탕 시험)
+- `GET …/plan/tile/{z}/{x}/{y}` — 위성 조각 대리 · 서버 기억(586 GL 바탕)
 - `GET …/plan/layers/sheet?key=` · `…/cadastral` · `…/raster?kind=slope|hillshade|landslide` ·
   `…/zones` · `…/soils` · `…/bands` · `…/lines?kind=` · `…/zero-order` ·
   `…/forest-roads`(GET · POST 올리기) · `…/landslide-zones` — 지도 겹
@@ -21,7 +21,7 @@ import json
 import logging
 from pathlib import Path
 from typing import Any
-from uuid import UUID
+from uuid import UUID, uuid4
 
 from fastapi import APIRouter, File, HTTPException, Request, Response, UploadFile
 from pydantic import BaseModel
@@ -350,22 +350,53 @@ async def plan_layer_landslide_zones(project_id: UUID) -> dict[str, Any]:
     return {"status": "success", **value}
 
 
+# 위성 조각 기억 — 프로젝트 → 실경로(조각마다 DB 를 안 부름)
+_TILE_ROOTS: dict[UUID, Path] = {}
+TILE_KIND = "plan_tile"
+
+
+async def _tile_root(project_id: UUID) -> Path:
+    root = _TILE_ROOTS.get(project_id)
+    if root is None:
+        async with get_db_pool().acquire() as connection:
+            stored = await get_project_storage_relative_path(connection, project_id)
+        if not stored:
+            raise HTTPException(status_code=404, detail="프로젝트 저장 경로를 찾을 수 없습니다.")
+        root = _TILE_ROOTS[project_id] = Path(resolve_stored_project_path(stored))
+    return root
+
+
 @router.get("/{project_id}/plan/tile/{z}/{x}/{y}", response_model=None)
 async def plan_satellite_tile(project_id: UUID, z: int, x: int, y: int) -> Response:
-    """위성 조각(PLAN 586-1 GL 바탕 시험 · 브이월드 Satellite z6~19) — 키가 화면에 안 새게 대리."""
+    """위성 조각(PLAN 586 GL 바탕 · 브이월드 Satellite z6~19) — 키가 화면에 안 새게 대리 ·
+    받은 조각 = `_derived/plan_tile/Satellite/{z}/{x}_{y}.jpeg`(지문 = 겹 · 조각 번호 ·
+    지워도 다시 받음)."""
     import urllib.request
 
     from B04_PreProcess.B04_PreProcess_Engine_VWorld import VWORLD_API_KEY
+    from common_util.common_util_derived_store import derived_dir
 
-    _ = project_id
     if not (6 <= z <= 19 and 0 <= x < 2**z and 0 <= y < 2**z):
         raise HTTPException(status_code=400, detail="조각 번호가 범위를 벗어났습니다.")
+    path = (
+        derived_dir(await _tile_root(project_id), TILE_KIND)
+        / "Satellite"
+        / str(z)
+        / f"{x}_{y}.jpeg"
+    )
     url = f"http://api.vworld.kr/req/wmts/1.0.0/{VWORLD_API_KEY}/Satellite/{z}/{y}/{x}.jpeg"
 
     def fetch() -> bytes:
+        if path.is_file():
+            return path.read_bytes()
         request = urllib.request.Request(url, headers={"User-Agent": "Aislo/1.0"})
         with urllib.request.urlopen(request, timeout=8) as response:
-            return response.read()
+            tile = response.read()
+        path.parent.mkdir(parents=True, exist_ok=True)
+        part = path.with_suffix(f".{uuid4().hex}.part")
+        part.write_bytes(tile)
+        part.replace(path)  # 반쯤 쓴 조각을 남기지 않음
+        return tile
 
     try:
         tile = await asyncio.to_thread(fetch)
diff --git a/resources/tester/test_586_tm_frame.py b/resources/tester/test_586_tm_frame.py
index 65ea8ed8f..99010ec38 100644
--- a/resources/tester/test_586_tm_frame.py
+++ b/resources/tester/test_586_tm_frame.py
@@ -134,3 +134,35 @@ def test_위성_조각_대리는_범위_밖을_막음():
         with pytest.raises(HTTPException) as error:
             asyncio.run(plan_satellite_tile(uuid.uuid4(), z, x, y))
         assert error.value.status_code == 400
+
+
+def test_위성_조각은_서버에_기억해_다시_안_받음(tmp_path, monkeypatch):
+    """586-2 — 받은 조각 = 프로젝트 `_derived/plan_tile` · 두 번째는 브이월드에 안 물음."""
+    import asyncio
+    import urllib.request
+    import uuid
+
+    from D03_PlanAnalysis import D03_PlanAnalysis_Router as router
+
+    project = uuid.uuid4()
+    monkeypatch.setitem(router._TILE_ROOTS, project, tmp_path)
+    calls = []
+
+    class Reply:
+        def __enter__(self):
+            return self
+
+        def __exit__(self, *_):
+            return False
+
+        def read(self):
+            return b"jpeg"
+
+    monkeypatch.setattr(urllib.request, "urlopen", lambda *a, **k: calls.append(1) or Reply())
+    for _ in range(2):
+        reply = asyncio.run(router.plan_satellite_tile(project, 14, 13990, 6380))
+        assert reply.body == b"jpeg"
+    assert len(calls) == 1
+    saved = tmp_path / "_derived" / "plan_tile" / "Satellite" / "14" / "13990_6380.jpeg"
+    assert saved.read_bytes() == b"jpeg"
+    assert not list(saved.parent.glob("*.part"))