diff --git a/app/api/documents.py b/app/api/documents.py
index 6a9ac08..6346223 100644
--- a/app/api/documents.py
+++ b/app/api/documents.py
@@ -37,6 +37,9 @@ class DocumentResponse(BaseModel):
     ai_tags: list | None
     ai_summary: str | None
     user_note: str | None
+    original_path: str | None
+    original_format: str | None
+    conversion_status: str | None
     edit_url: str | None
     preview_status: str | None
     source_channel: str | None
diff --git a/app/models/document.py b/app/models/document.py
index fa13499..fd69c46 100644
--- a/app/models/document.py
+++ b/app/models/document.py
@@ -47,6 +47,12 @@ class Document(Base):
     # 사용자 메모
     user_note: Mapped[str | None] = mapped_column(Text)
 
+    # 원본 보존 (변환 전)
+    original_path: Mapped[str | None] = mapped_column(Text)
+    original_format: Mapped[str | None] = mapped_column(String(20))
+    original_hash: Mapped[str | None] = mapped_column(String(64))
+    conversion_status: Mapped[str | None] = mapped_column(String(20), default="none")
+
     # 외부 편집 URL
     edit_url: Mapped[str | None] = mapped_column(Text)
 
diff --git a/app/workers/extract_worker.py b/app/workers/extract_worker.py
index 3ea3925..98608b2 100644
--- a/app/workers/extract_worker.py
+++ b/app/workers/extract_worker.py
@@ -117,6 +117,55 @@ async def process(document_id: int, session: AsyncSession) -> None:
             raise RuntimeError(f"LibreOffice 텍스트 추출 timeout (60s)")
         finally:
             tmp_input.unlink(missing_ok=True)
+
+        # ─── ODF 변환 (편집용) ───
+        CONVERT_MAP = {
+            'xlsx': 'ods', 'xls': 'ods',
+            'docx': 'odt', 'doc': 'odt',
+            'pptx': 'odp', 'ppt': 'odp',
+        }
+        target_fmt = CONVERT_MAP.get(fmt)
+        if target_fmt:
+            try:
+                from core.utils import file_hash as calc_hash
+                # 원본 메타 보존
+                doc.original_path = doc.file_path
+                doc.original_format = doc.file_format
+                doc.original_hash = doc.file_hash
+
+                # .derived 디렉토리에 변환
+                derived_dir = full_path.parent / ".derived"
+                derived_dir.mkdir(exist_ok=True)
+                tmp_input2 = tmp_dir / f"convert_{document_id}.{fmt}"
+                shutil.copy2(str(full_path), str(tmp_input2))
+
+                conv_result = subprocess.run(
+                    ["libreoffice", "--headless", "--convert-to", target_fmt, "--outdir", str(tmp_dir), str(tmp_input2)],
+                    capture_output=True, text=True, timeout=60,
+                )
+                tmp_input2.unlink(missing_ok=True)
+
+                conv_file = tmp_dir / f"convert_{document_id}.{target_fmt}"
+                if conv_file.exists():
+                    final_path = derived_dir / f"{document_id}.{target_fmt}"
+                    shutil.move(str(conv_file), str(final_path))
+
+                    # DB 업데이트: current → ODF
+                    nas_root = Path(settings.nas_mount_path)
+                    doc.file_path = str(final_path.relative_to(nas_root))
+                    doc.file_format = target_fmt
+                    doc.file_hash = calc_hash(final_path)
+                    doc.conversion_status = "done"
+                    logger.info(f"[ODF변환] {doc.original_path} → {doc.file_path}")
+                else:
+                    doc.conversion_status = "failed"
+                    logger.warning(f"[ODF변환] 실패: {conv_result.stderr[:200]}")
+            except Exception as e:
+                doc.conversion_status = "failed"
+                logger.error(f"[ODF변환] {doc.file_path} 에러: {e}")
+        else:
+            doc.conversion_status = "none"
+
         return
 
     # 미지원 포맷
diff --git a/app/workers/file_watcher.py b/app/workers/file_watcher.py
index 4600314..c4cacca 100644
--- a/app/workers/file_watcher.py
+++ b/app/workers/file_watcher.py
@@ -22,6 +22,9 @@ def should_skip(path: Path) -> bool:
         return True
     if path.suffix.lower() in SKIP_EXTENSIONS:
         return True
+    # .derived/ 및 .preview/ 디렉토리 내 파일 제외
+    if ".derived" in path.parts or ".preview" in path.parts:
+        return True
     return False
 
 
diff --git a/frontend/src/lib/components/DocumentViewer.svelte b/frontend/src/lib/components/DocumentViewer.svelte
index 8393067..268a71a 100644
--- a/frontend/src/lib/components/DocumentViewer.svelte
+++ b/frontend/src/lib/components/DocumentViewer.svelte
@@ -25,11 +25,15 @@
     return 'unsupported';
   }
 
-  function getEditUrl(doc) {
+  const ODF_FORMATS = ['ods', 'odt', 'odp', 'odoc', 'osheet'];
+
+  function getEditInfo(doc) {
     // DB에 저장된 편집 URL 우선
-    if (doc.edit_url) return doc.edit_url;
-    // CAD는 AutoCAD Web
-    if (['dwg', 'dxf'].includes(doc.file_format)) return 'https://web.autocad.com';
+    if (doc.edit_url) return { url: doc.edit_url, label: '편집' };
+    // ODF 포맷 → Synology Drive
+    if (ODF_FORMATS.includes(doc.file_format)) return { url: 'https://link.hyungi.net', label: 'Synology Drive에서 열기' };
+    // CAD
+    if (['dwg', 'dxf'].includes(doc.file_format)) return { url: 'https://web.autocad.com', label: 'AutoCAD Web' };
     return null;
   }
 
@@ -82,7 +86,7 @@
     }
   }
 
-  let editUrl = $derived(fullDoc ? getEditUrl(fullDoc) : null);
+  let editInfo = $derived(fullDoc ? getEditInfo(fullDoc) : null);
 </script>
 
 <svelte:window on:keydown={handleKeydown} />
@@ -113,14 +117,14 @@
             >편집</button>
           {/if}
         {/if}
-        {#if editUrl}
+        {#if editInfo}
           <a
-            href={editUrl}
+            href={editInfo.url}
             target="_blank"
             rel="noopener"
             class="flex items-center gap-1 px-2 py-1 text-xs text-[var(--text-dim)] hover:text-[var(--accent)] border border-[var(--border)] rounded"
           >
-            <ExternalLink size={12} /> 편집
+            <ExternalLink size={12} /> {editInfo.label}
           </a>
         {/if}
         <a
diff --git a/migrations/007_original_fields.sql b/migrations/007_original_fields.sql
new file mode 100644
index 0000000..d2fb929
--- /dev/null
+++ b/migrations/007_original_fields.sql
@@ -0,0 +1,5 @@
+-- 원본/변환 분리 필드 추가
+ALTER TABLE documents ADD COLUMN IF NOT EXISTS original_path TEXT;
+ALTER TABLE documents ADD COLUMN IF NOT EXISTS original_format VARCHAR(20);
+ALTER TABLE documents ADD COLUMN IF NOT EXISTS original_hash VARCHAR(64);
+ALTER TABLE documents ADD COLUMN IF NOT EXISTS conversion_status VARCHAR(20) DEFAULT 'none';