feat(folders): nested folder tree (max depth 2) + id-based mutations

- new storeDb.ts: DB+FS layer (folders w/ parent_id, videos w/ global id) - depth cap: sub-folder cannot have children (enforced in createFolder) - video id: editable anytime (changeVideoId), uniqueness via PK - routes: - public /folder/:topName[/:subName], /video/:topName[/:subName]/:videoId - admin /op/folder/:topName[/:subName], id-based /op/folders/:id/* and /op/videos/:id/* (rename/changeId/delete/save + idAvailable check) - views: breadcrumb + subFolder grid; 플레이리스트 추가 button shows at 2단계 - client JS: id-based mutation endpoints, share URL data attribute, in-site player pushes share URL to address bar - store.ts slimmed to Account + readAccounts (FS layer moved to storeDb) - pickIntId accepts numeric JSON bodies Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
2026-05-31 23:36:02 +09:00
parent 3560dcb802
commit c5faa8808c
17 changed files with 1207 additions and 577 deletions
--- a/public/dashboard.js
+++ b/public/dashboard.js
@@ -1,5 +1,6 @@
 (function () {
  var ctxMenu = document.getElementById('ctxMenu')
+  var targetId = null
  var targetName = null

  function showCtx(x, y) {
@@ -7,11 +8,12 @@
    ctxMenu.style.top = y + 'px'
    ctxMenu.hidden = false
  }
-  function hideCtx() { ctxMenu.hidden = true; targetName = null }
+  function hideCtx() { ctxMenu.hidden = true; targetId = null; targetName = null }

  document.querySelectorAll('.adminFolder').forEach(function (card) {
    card.addEventListener('contextmenu', function (e) {
      e.preventDefault()
+      targetId = card.getAttribute('data-folder-id')
      targetName = card.getAttribute('data-name')
      showCtx(e.clientX, e.clientY)
    })
@@ -23,15 +25,15 @@

  ctxMenu.addEventListener('click', function (e) {
    var btn = e.target.closest('button')
-    if (!btn) return
+    if (!btn || !targetId) return
    var action = btn.getAttribute('data-action')
    if (action === 'rename') {
      var newName = window.prompt('새 폴더 이름', targetName)
      if (newName && newName !== targetName) {
-        fetch('/op/folders/rename', {
+        fetch('/op/folders/' + encodeURIComponent(targetId) + '/rename', {
          method: 'POST',
          headers: { 'content-type': 'application/json' },
-          body: JSON.stringify({ oldName: targetName, newName: newName })
+          body: JSON.stringify({ newName: newName })
        }).then(function (r) { return r.json() }).then(function (j) {
          if (j.ok) location.reload()
          else alert(j.message || '이름 변경 실패')
@@ -39,10 +41,8 @@
      }
    } else if (action === 'delete') {
      if (window.confirm('"' + targetName + '" 폴더를 정말 삭제할까요? 안의 영상이 모두 사라집니다.')) {
-        fetch('/op/folders/delete', {
-          method: 'POST',
-          headers: { 'content-type': 'application/json' },
-          body: JSON.stringify({ name: targetName })
+        fetch('/op/folders/' + encodeURIComponent(targetId) + '/delete', {
+          method: 'POST'
        }).then(function (r) { return r.json() }).then(function (j) {
          if (j.ok) location.reload()
          else alert(j.message || '삭제 실패')
@@ -61,6 +61,7 @@

  function openModal() { modal.hidden = false; input.value = ''; setTimeout(function () { input.focus() }, 0) }
  function closeModal() { modal.hidden = true }
+  if (addBtn) {
    addBtn.addEventListener('click', openModal)
    cancelBtn.addEventListener('click', closeModal)
    modal.addEventListener('click', function (e) { if (e.target === modal) closeModal() })
@@ -77,4 +78,5 @@
        else alert(j.message || '폴더 생성 실패')
      })
    })
+  }
 })()
--- a/public/editor.js
+++ b/public/editor.js
@@ -1,6 +1,7 @@
 (function () {
-  var ctx = window.__EDITOR__ || { folder: '', video: null }
-  var folder = ctx.folder
+  var ctx = window.__EDITOR__ || { folderPath: [], folderId: null, video: null }
+  var folderPathEnc = (ctx.folderPath || []).map(encodeURIComponent).join('/')
+  var folderBaseUrl = '/op/folder/' + folderPathEnc
  var video = ctx.video

  var dropZone = document.getElementById('dropZone')
@@ -46,7 +47,7 @@
    form.append('title', titleInput.value || file.name)
    uploadStatus.textContent = '업로드 중...'
    var xhr = new XMLHttpRequest()
-    xhr.open('POST', '/op/folder/' + encodeURIComponent(folder) + '/video/upload')
+    xhr.open('POST', folderBaseUrl + '/video/upload')
    xhr.upload.addEventListener('progress', function (e) {
      if (e.lengthComputable) {
        var pct = Math.round((e.loaded / e.total) * 100)
@@ -57,7 +58,7 @@
      try {
        var res = JSON.parse(xhr.responseText)
        if (res.ok) {
-          location.href = '/op/folder/' + encodeURIComponent(folder) + '/video/editor?id=' + encodeURIComponent(res.videoId)
+          location.href = folderBaseUrl + '/video/editor?id=' + encodeURIComponent(res.videoId)
        } else {
          uploadStatus.textContent = '업로드 실패: ' + (res.message || '')
        }
@@ -89,7 +90,7 @@
    probeInfo.textContent = '확인 중...'
    ytProbeBtn.disabled = true
    ytStartBtn.disabled = true
-    fetch('/op/folder/' + encodeURIComponent(folder) + '/video/youtube/probe', {
+    fetch(folderBaseUrl + '/video/youtube/probe', {
      method: 'POST',
      headers: { 'content-type': 'application/json' },
      body: JSON.stringify({ url: url })
@@ -144,7 +145,7 @@
    }
    // 중복 클릭 방지
    ytStartBtn.disabled = true
-    fetch('/op/folder/' + encodeURIComponent(folder) + '/video/youtube/start', {
+    fetch(folderBaseUrl + '/video/youtube/start', {
      method: 'POST',
      headers: { 'content-type': 'application/json' },
      body: JSON.stringify({ url: url, title: titleInput.value })
@@ -180,7 +181,7 @@
        dlProgress.value = job.progress
        probeInfo.textContent = job.message
        if (job.status === 'done') {
-          location.href = '/op/folder/' + encodeURIComponent(folder) + '/video/editor?id=' + encodeURIComponent(videoId)
+          location.href = folderBaseUrl + '/video/editor?id=' + encodeURIComponent(videoId)
        } else if (job.status === 'error') {
          probeInfo.textContent = '실패: ' + (job.error || '')
        } else {
@@ -364,14 +365,13 @@
  saveBtn.addEventListener('click', function () {
    if (!video) { alert('먼저 영상을 추가하세요.'); return }
    var payload = {
-      id: video.id,
      title: titleInput.value,
      startSec: trimStart,
      endSec: trimEnd
    }
    saveBtn.disabled = true
    saveBtn.textContent = '저장 중...'
-    fetch('/op/folder/' + encodeURIComponent(folder) + '/video/save', {
+    fetch('/op/videos/' + encodeURIComponent(video.id) + '/save', {
      method: 'POST',
      headers: { 'content-type': 'application/json' },
      body: JSON.stringify(payload)
@@ -380,7 +380,7 @@
      saveBtn.textContent = '저장'
      if (j.ok) {
        alert(j.note || '저장 완료')
-        location.href = '/op/folder/' + encodeURIComponent(folder)
+        location.href = folderBaseUrl
      } else {
        alert(j.message || '저장 실패')
      }
--- a/public/folder.js
+++ b/public/folder.js
@@ -1,74 +1,171 @@
 (function () {
-  var folder = (window.__OP__ || {}).folder
-  var ctxMenu = document.getElementById('ctxMenu')
-  var targetId = null
-  var targetTitle = null
+  var op = window.__OP__ || { folderId: null, folderPath: [], isSubFolder: false }
+  var folderPathEnc = (op.folderPath || []).map(encodeURIComponent).join('/')

-  function showCtx(x, y) {
-    ctxMenu.style.left = x + 'px'
-    ctxMenu.style.top = y + 'px'
-    ctxMenu.hidden = false
+  // ── 영상 컨텍스트 메뉴 ───────────────────────────────────────────────
+  var videoCtxMenu = document.getElementById('ctxMenu')
+  var videoTargetId = null
+  var videoTargetTitle = null
+  var videoTargetShareUrl = null
+
+  function showVideoCtx(x, y) {
+    videoCtxMenu.style.left = x + 'px'
+    videoCtxMenu.style.top = y + 'px'
+    videoCtxMenu.hidden = false
  }
-  function hideCtx() { ctxMenu.hidden = true }
+  function hideVideoCtx() { videoCtxMenu.hidden = true }

  document.querySelectorAll('.adminVideo').forEach(function (card) {
    card.addEventListener('contextmenu', function (e) {
      e.preventDefault()
-      targetId = card.getAttribute('data-id')
-      targetTitle = card.getAttribute('data-title')
-      showCtx(e.clientX, e.clientY)
+      videoTargetId = card.getAttribute('data-id')
+      videoTargetTitle = card.getAttribute('data-title')
+      videoTargetShareUrl = card.getAttribute('data-share-url')
+      showVideoCtx(e.clientX, e.clientY)
    })
  })

-  document.addEventListener('click', function (e) {
-    if (!ctxMenu.contains(e.target)) hideCtx()
-  })
-
-  ctxMenu.addEventListener('click', function (e) {
+  videoCtxMenu.addEventListener('click', function (e) {
    var btn = e.target.closest('button')
-    if (!btn) return
+    if (!btn || !videoTargetId) return
    var action = btn.getAttribute('data-action')
    if (action === 'edit') {
-      location.href = '/op/folder/' + encodeURIComponent(folder) + '/video/editor?id=' + encodeURIComponent(targetId)
+      location.href = '/op/folder/' + folderPathEnc + '/video/editor?id=' + encodeURIComponent(videoTargetId)
    } else if (action === 'copyUrl') {
-      copyVideoUrl(targetId)
+      copyUrl(location.origin + videoTargetShareUrl)
    } else if (action === 'rename') {
-      var t = window.prompt('새 영상 제목', targetTitle)
-      if (t && t !== targetTitle) {
-        fetch('/op/folder/' + encodeURIComponent(folder) + '/video/rename', {
+      var t = window.prompt('새 영상 제목', videoTargetTitle)
+      if (t && t !== videoTargetTitle) {
+        fetch('/op/videos/' + encodeURIComponent(videoTargetId) + '/rename', {
          method: 'POST',
          headers: { 'content-type': 'application/json' },
-          body: JSON.stringify({ id: targetId, title: t })
+          body: JSON.stringify({ title: t })
        }).then(function (r) { return r.json() }).then(function (j) {
          if (j.ok) location.reload()
          else alert(j.message || '이름 변경 실패')
        })
      }
-    } else if (action === 'delete') {
-      if (window.confirm('"' + targetTitle + '" 영상을 정말 삭제할까요?')) {
-        fetch('/op/folder/' + encodeURIComponent(folder) + '/video/delete', {
+    } else if (action === 'changeId') {
+      var newId = window.prompt('새 영상 ID (영문/숫자/_/-, 1~64자)', videoTargetId)
+      if (newId && newId !== videoTargetId) {
+        fetch('/op/videos/' + encodeURIComponent(videoTargetId) + '/changeId', {
          method: 'POST',
          headers: { 'content-type': 'application/json' },
-          body: JSON.stringify({ id: targetId })
+          body: JSON.stringify({ newId: newId })
+        }).then(function (r) { return r.json() }).then(function (j) {
+          if (j.ok) location.reload()
+          else alert(j.message || 'ID 변경 실패')
+        })
+      }
+    } else if (action === 'delete') {
+      if (window.confirm('"' + videoTargetTitle + '" 영상을 정말 삭제할까요?')) {
+        fetch('/op/videos/' + encodeURIComponent(videoTargetId) + '/delete', {
+          method: 'POST'
        }).then(function (r) { return r.json() }).then(function (j) {
          if (j.ok) location.reload()
          else alert(j.message || '삭제 실패')
        })
      }
    }
-    hideCtx()
+    hideVideoCtx()
  })

-  function copyVideoUrl(id) {
-    var url = location.origin + '/file/video/' + encodeURIComponent(id)
-    if (navigator.clipboard && navigator.clipboard.writeText) {
-      navigator.clipboard.writeText(url).then(function () {
-        flashToast('주소가 복사되었습니다.')
-      }, function () {
-        fallbackCopy(url)
+  // ── 하위 폴더 컨텍스트 메뉴 (rename / delete) ────────────────────────
+  var folderCtxMenu = document.getElementById('folderCtxMenu')
+  var folderTargetId = null
+  var folderTargetName = null
+
+  function showFolderCtx(x, y) {
+    folderCtxMenu.style.left = x + 'px'
+    folderCtxMenu.style.top = y + 'px'
+    folderCtxMenu.hidden = false
+  }
+  function hideFolderCtx() { folderCtxMenu.hidden = true }
+
+  document.querySelectorAll('#subFolderGrid .adminFolder').forEach(function (card) {
+    card.addEventListener('contextmenu', function (e) {
+      e.preventDefault()
+      folderTargetId = card.getAttribute('data-folder-id')
+      folderTargetName = card.getAttribute('data-name')
+      showFolderCtx(e.clientX, e.clientY)
    })
+  })
+
+  if (folderCtxMenu) {
+    folderCtxMenu.addEventListener('click', function (e) {
+      var btn = e.target.closest('button')
+      if (!btn || !folderTargetId) return
+      var action = btn.getAttribute('data-action')
+      if (action === 'rename') {
+        var newName = window.prompt('새 폴더 이름', folderTargetName)
+        if (newName && newName !== folderTargetName) {
+          fetch('/op/folders/' + encodeURIComponent(folderTargetId) + '/rename', {
+            method: 'POST',
+            headers: { 'content-type': 'application/json' },
+            body: JSON.stringify({ newName: newName })
+          }).then(function (r) { return r.json() }).then(function (j) {
+            if (j.ok) location.reload()
+            else alert(j.message || '이름 변경 실패')
+          })
+        }
+      } else if (action === 'delete') {
+        if (window.confirm('"' + folderTargetName + '" 폴더를 정말 삭제할까요? 안의 영상이 모두 사라집니다.')) {
+          fetch('/op/folders/' + encodeURIComponent(folderTargetId) + '/delete', {
+            method: 'POST'
+          }).then(function (r) { return r.json() }).then(function (j) {
+            if (j.ok) location.reload()
+            else alert(j.message || '삭제 실패')
+          })
+        }
+      }
+      hideFolderCtx()
+    })
+  }
+
+  document.addEventListener('click', function (e) {
+    if (videoCtxMenu && !videoCtxMenu.contains(e.target)) hideVideoCtx()
+    if (folderCtxMenu && !folderCtxMenu.contains(e.target)) hideFolderCtx()
+  })
+
+  // ── 하위 폴더 추가 모달 ──────────────────────────────────────────────
+  var addSubBtn = document.getElementById('addSubFolderBtn')
+  if (addSubBtn) {
+    var subModal = document.getElementById('addSubFolderModal')
+    var subInput = document.getElementById('addSubFolderInput')
+    var subCancel = document.getElementById('addSubFolderCancel')
+    var subConfirm = document.getElementById('addSubFolderConfirm')
+
+    function openSubModal() {
+      subModal.hidden = false; subInput.value = ''
+      setTimeout(function () { subInput.focus() }, 0)
+    }
+    function closeSubModal() { subModal.hidden = true }
+    addSubBtn.addEventListener('click', openSubModal)
+    subCancel.addEventListener('click', closeSubModal)
+    subModal.addEventListener('click', function (e) { if (e.target === subModal) closeSubModal() })
+    subInput.addEventListener('keydown', function (e) { if (e.key === 'Enter') subConfirm.click() })
+    subConfirm.addEventListener('click', function () {
+      var name = subInput.value.trim()
+      if (!name) return
+      fetch('/op/folders', {
+        method: 'POST',
+        headers: { 'content-type': 'application/json' },
+        body: JSON.stringify({ name: name, parentId: op.folderId })
+      }).then(function (r) { return r.json() }).then(function (j) {
+        if (j.ok) location.reload()
+        else alert(j.message || '폴더 생성 실패')
+      })
+    })
+  }
+
+  // ── 유틸 ──────────────────────────────────────────────────────────
+  function copyUrl(text) {
+    if (navigator.clipboard && navigator.clipboard.writeText) {
+      navigator.clipboard.writeText(text).then(function () {
+        flashToast('주소가 복사되었습니다.')
+      }, function () { fallbackCopy(text) })
    } else {
-      fallbackCopy(url)
+      fallbackCopy(text)
    }
  }
  function fallbackCopy(text) {
--- a/public/player.js
+++ b/public/player.js
@@ -1,13 +1,15 @@
 (function () {
  var overlay = document.getElementById('playerOverlay')
+  if (!overlay) return
  var closeBtn = document.getElementById('playerClose')
  var video = document.getElementById('playerVideo')
  var titleEl = document.getElementById('playerTitle')

-  function openPlayer(videoId, title) {
-    // 스펙: /player/:videoId 로 이동한 것처럼 동작하면서 내부 팝업으로 띄운다.
-    // pushState 로 URL 만 바꿔, 새로고침/직접접근 시 player.ejs 가 응답한다.
-    history.pushState({ player: true, videoId: videoId }, '', '/player/' + encodeURIComponent(videoId))
+  function openPlayer(videoId, title, shareUrl) {
+    // 사이트 내 재생도 share URL 을 주소창에 보이도록 pushState.
+    // share URL 이 없으면 단순한 /file/video/:id 로 폴백.
+    var url = shareUrl || ('/file/video/' + encodeURIComponent(videoId))
+    history.pushState({ player: true, videoId: videoId }, '', url)
    titleEl.textContent = title || ''
    video.src = '/api/video/' + encodeURIComponent(videoId) + '/file'
    overlay.hidden = false
@@ -19,17 +21,19 @@
    video.pause()
    video.removeAttribute('src')
    video.load()
-    // 폴더 페이지로 되돌리기
    if (history.state && history.state.player) {
      history.back()
    }
  }

  document.querySelectorAll('.videoCard').forEach(function (card) {
+    // <a> 태그면 클릭 시 share URL 로 풀 페이지 이동하도록 두고, 모달은 띄우지 않는다.
+    if (card.tagName && card.tagName.toLowerCase() === 'a') return
    card.addEventListener('click', function () {
      var id = card.getAttribute('data-video-id')
-      var title = card.querySelector('.videoTitle')
-      openPlayer(id, title ? title.textContent : '')
+      var titleNode = card.querySelector('.videoTitle')
+      var shareUrl = card.getAttribute('data-share-url')
+      openPlayer(id, titleNode ? titleNode.textContent : '', shareUrl)
    })
  })

--- a/public/public-folder.js
+++ b/public/public-folder.js
@@ -1,7 +1,7 @@
 (function () {
  var ctxMenu = document.getElementById('ctxMenu')
  if (!ctxMenu) return
-  var targetId = null
+  var targetShareUrl = null

  function showCtx(x, y) {
    ctxMenu.style.left = x + 'px'
@@ -13,7 +13,7 @@
  document.querySelectorAll('.videoCard').forEach(function (card) {
    card.addEventListener('contextmenu', function (e) {
      e.preventDefault()
-      targetId = card.getAttribute('data-video-id') || card.getAttribute('data-id')
+      targetShareUrl = card.getAttribute('data-share-url')
      showCtx(e.clientX, e.clientY)
    })
  })
@@ -27,22 +27,19 @@
    var btn = e.target.closest('button')
    if (!btn) return
    var action = btn.getAttribute('data-action')
-    if (action === 'copyUrl' && targetId) {
-      copyVideoUrl(targetId)
+    if (action === 'copyUrl' && targetShareUrl) {
+      copyUrl(location.origin + targetShareUrl)
    }
    hideCtx()
  })

-  function copyVideoUrl(id) {
-    var url = location.origin + '/file/video/' + encodeURIComponent(id)
+  function copyUrl(text) {
    if (navigator.clipboard && navigator.clipboard.writeText) {
-      navigator.clipboard.writeText(url).then(function () {
+      navigator.clipboard.writeText(text).then(function () {
        flashToast('주소가 복사되었습니다.')
-      }, function () {
-        fallbackCopy(url)
-      })
+      }, function () { fallbackCopy(text) })
    } else {
-      fallbackCopy(url)
+      fallbackCopy(text)
    }
  }
  function fallbackCopy(text) {
--- a/src/editor.ts
+++ b/src/editor.ts
@@ -1,7 +1,7 @@
 import { spawn, spawnSync } from 'node:child_process'
 import { promises as fs } from 'node:fs'
 import path from 'node:path'
-import { videoDir, loadVideoMeta, saveVideoMeta, type VideoTrim } from './store.js'
+import { getVideo, updateVideo, videoDiskDir, type VideoTrim } from './storeDb.js'

 export class FfmpegUnavailableError extends Error {
  constructor() {
@@ -184,14 +184,13 @@ export async function upscaleOriginalTo60Fps(
 * stream copy 를 우선 시도해 빠르게 자르고, 실패하면 재인코딩.
 */
 export async function applyTrimToVideo(
-  folder: string,
  videoId: string,
  trim: VideoTrim
 ): Promise<string> {
  const bin = getFfmpegPath()
-  const meta = await loadVideoMeta(folder, videoId)
+  const meta = getVideo(videoId)
  if (!meta) throw new Error('비디오를 찾을 수 없습니다.')
-  const dir = videoDir(folder, videoId)
+  const dir = videoDiskDir(videoId)
  const inputPath = path.join(dir, meta.originalFile)
  await fs.access(inputPath)

@@ -236,9 +235,10 @@ export async function applyTrimToVideo(
  }
  await fs.rename(tmpPath, outPath)

-  meta.editedFile = outName
-  meta.trim = { startSec, endSec }
-  await saveVideoMeta(folder, meta)
+  updateVideo(videoId, {
+    editedFile: outName,
+    trim: { startSec, endSec }
+  })
  return outName
 }

--- a/src/routes/op.ts
+++ b/src/routes/op.ts
@@ -2,24 +2,26 @@ import { Router } from 'express'
 import path from 'node:path'
 import multer, { MulterError } from 'multer'
 import type { Request, Response, NextFunction } from 'express'
-import { promises as fs } from 'node:fs'
 import { requireAuth } from '../auth.js'
+import { readAccounts } from '../store.js'
 import {
+  changeVideoId,
  createFolder,
+  createVideo,
  deleteFolder,
  deleteVideo,
-  folderPath,
-  listFolders,
-  listVideos,
-  loadVideoMeta,
-  moveUploadIntoVideo,
-  newVideoId,
-  readAccounts,
+  folderPathNames,
+  getFolder,
+  getFolderByPath,
+  getVideo,
+  listChildFolders,
+  listTopFolders,
+  listVideosInFolder,
+  moveUploadIntoVideoDir,
  renameFolder,
-  sanitizeFolderName,
-  saveVideoMeta,
-  type VideoMeta
-} from '../store.js'
+  updateVideo,
+  videoIdExists
+} from '../storeDb.js'
 import { tmpDir } from '../paths.js'
 import {
  YtDlpUnavailableError,
@@ -32,9 +34,6 @@ import { FfmpegUnavailableError, applyTrimToVideo } from '../editor.js'
 export const opRouter = Router()

 // 업로드 용량 상한. 기본 1 GiB. UPLOAD_MAX_BYTES 환경변수로 변경 가능.
-// - 비어있거나 미설정이면 기본 1 GiB
-// - "0" 또는 "Infinity" 만 명시적 무제한으로 인정
-// - 잘못된 값 (오타 등) 은 기본 1 GiB 로 fallback (경고 출력)
 const DEFAULT_UPLOAD_MAX_BYTES = 1024 * 1024 * 1024
 const uploadMaxBytes = (() => {
  const raw = process.env.UPLOAD_MAX_BYTES
@@ -43,7 +42,9 @@ const uploadMaxBytes = (() => {
  if (trimmed === '0' || trimmed.toLowerCase() === 'infinity') return Infinity
  const n = Number(trimmed)
  if (!Number.isFinite(n) || n <= 0) {
-    console.warn(`[upload] invalid UPLOAD_MAX_BYTES=${JSON.stringify(raw)}; falling back to default ${DEFAULT_UPLOAD_MAX_BYTES} bytes`)
+    console.warn(
+      `[upload] invalid UPLOAD_MAX_BYTES=${JSON.stringify(raw)}; falling back to default ${DEFAULT_UPLOAD_MAX_BYTES} bytes`
+    )
    return DEFAULT_UPLOAD_MAX_BYTES
  }
  return Math.max(1, Math.floor(n))
@@ -58,6 +59,22 @@ function pickStr(v: unknown): string {
  return typeof v === 'string' ? v : ''
 }

+function pickIntId(v: unknown): number | null {
+  // JSON body 로 들어오면 number, form 으로 들어오면 string. 둘 다 지원.
+  let n: number
+  if (typeof v === 'number') {
+    n = v
+  } else {
+    const s = pickStr(v).trim()
+    if (!s) return null
+    n = Number(s)
+  }
+  if (!Number.isFinite(n) || n < 1 || Math.floor(n) !== n) return null
+  return n
+}
+
+// ─── 인증 ─────────────────────────────────────────────────────────────
+
 opRouter.get('/op', (req, res) => {
  if (req.session?.userId) {
    res.redirect('/op/dashboard')
@@ -88,119 +105,114 @@ opRouter.post('/op/logout', (req, res) => {
  })
 })

-opRouter.get('/op/dashboard', requireAuth, async (req, res, next) => {
+// ─── 폴더 뷰 ──────────────────────────────────────────────────────────
+
+opRouter.get('/op/dashboard', requireAuth, (req, res, next) => {
  try {
-    const folders = await listFolders()
+    const folders = listTopFolders()
    res.render('op/dashboard', { userId: req.session.userId, folders })
  } catch (err) {
    next(err)
  }
 })

-opRouter.post('/op/folders', requireAuth, async (req, res, next) => {
+function folderViewHandler(req: Request, res: Response, next: NextFunction): void {
+  try {
+    const segments = collectFolderSegments(req.params)
+    const folder = getFolderByPath(segments)
+    if (!folder) {
+      res.status(404).send('폴더를 찾을 수 없습니다.')
+      return
+    }
+    const subFolders = folder.parentId === null ? listChildFolders(folder.id) : []
+    const videos = listVideosInFolder(folder.id)
+    res.render('op/folder', {
+      userId: req.session.userId,
+      folder,
+      breadcrumb: folderPathNames(folder.id),
+      subFolders,
+      videos,
+      isSubFolder: folder.parentId !== null
+    })
+  } catch (err) {
+    next(err)
+  }
+}
+opRouter.get('/op/folder/:topName', requireAuth, folderViewHandler)
+opRouter.get('/op/folder/:topName/:subName', requireAuth, folderViewHandler)
+
+// ─── 폴더 mutation (id 기반) ───────────────────────────────────────────
+
+opRouter.post('/op/folders', requireAuth, async (req, res) => {
  try {
    const name = pickStr(req.body.name)
-    const safe = await createFolder(name)
-    res.json({ ok: true, name: safe })
+    const parentIdRaw = req.body.parentId
+    const parentId =
+      parentIdRaw === undefined || parentIdRaw === null || parentIdRaw === ''
+        ? null
+        : pickIntId(parentIdRaw)
+    if (parentIdRaw !== undefined && parentIdRaw !== null && parentIdRaw !== '' && parentId === null) {
+      throw new Error('상위 폴더 ID 가 올바르지 않습니다.')
+    }
+    const folder = await createFolder({ name, parentId })
+    res.json({ ok: true, folder })
  } catch (err) {
    res.status(400).json({ ok: false, message: (err as Error).message })
  }
 })

-opRouter.post('/op/folders/rename', requireAuth, async (req, res) => {
+opRouter.post('/op/folders/:id/rename', requireAuth, async (req, res) => {
  try {
-    const oldName = pickStr(req.body.oldName)
+    const id = pickIntId(req.params.id)
+    if (id === null) throw new Error('폴더 ID 가 올바르지 않습니다.')
    const newName = pickStr(req.body.newName)
-    const result = await renameFolder(oldName, newName)
-    res.json({ ok: true, name: result })
+    const folder = await renameFolder(id, newName)
+    res.json({ ok: true, folder })
  } catch (err) {
    res.status(400).json({ ok: false, message: (err as Error).message })
  }
 })

-opRouter.post('/op/folders/delete', requireAuth, async (req, res) => {
+opRouter.post('/op/folders/:id/delete', requireAuth, async (req, res) => {
  try {
-    const name = pickStr(req.body.name)
-    await deleteFolder(name)
+    const id = pickIntId(req.params.id)
+    if (id === null) throw new Error('폴더 ID 가 올바르지 않습니다.')
+    await deleteFolder(id)
    res.json({ ok: true })
  } catch (err) {
    res.status(400).json({ ok: false, message: (err as Error).message })
  }
 })

-opRouter.get('/op/folder/:name', requireAuth, async (req, res, next) => {
-  try {
-    const safe = sanitizeFolderName(req.params.name)
-    if (!safe) {
-      res.status(404).send('폴더를 찾을 수 없습니다.')
-      return
-    }
-    try {
-      await fs.access(folderPath(safe))
-    } catch {
-      res.status(404).send('폴더를 찾을 수 없습니다.')
-      return
-    }
-    const videos = await listVideos(safe)
-    res.render('op/folder', { userId: req.session.userId, folder: safe, videos })
-  } catch (err) {
-    next(err)
-  }
-})
+// ─── 영상 에디터 페이지 ────────────────────────────────────────────────

-opRouter.get('/op/folder/:name/video/editor', requireAuth, async (req, res, next) => {
+opRouter.get(
+  ['/op/folder/:topName/video/editor', '/op/folder/:topName/:subName/video/editor'],
+  requireAuth,
+  (req, res, next) => {
    try {
-    const safe = sanitizeFolderName(req.params.name)
-    if (!safe) {
+      const segments = collectFolderSegments(req.params)
+      const folder = getFolderByPath(segments)
+      if (!folder) {
        res.status(404).send('폴더를 찾을 수 없습니다.')
        return
      }
      const videoId = typeof req.query.id === 'string' ? req.query.id : null
-    let video: VideoMeta | null = null
-    if (videoId) {
-      video = await loadVideoMeta(safe, videoId)
-    }
+      const video = videoId ? getVideo(videoId) : null
      res.render('op/editor', {
        userId: req.session.userId,
-      folder: safe,
+        folder,
+        breadcrumb: folderPathNames(folder.id),
        video
      })
    } catch (err) {
      next(err)
    }
-})
-
-opRouter.post('/op/folder/:name/video/rename', requireAuth, async (req, res) => {
-  try {
-    const safe = sanitizeFolderName(req.params.name)
-    if (!safe) throw new Error('폴더 이름이 올바르지 않습니다.')
-    const id = pickStr(req.body.id)
-    const title = pickStr(req.body.title).trim()
-    if (!title) throw new Error('제목을 입력해 주세요.')
-    const meta = await loadVideoMeta(safe, id)
-    if (!meta) throw new Error('영상을 찾을 수 없습니다.')
-    meta.title = title
-    await saveVideoMeta(safe, meta)
-    res.json({ ok: true })
-  } catch (err) {
-    res.status(400).json({ ok: false, message: (err as Error).message })
  }
-})
+)

-opRouter.post('/op/folder/:name/video/delete', requireAuth, async (req, res) => {
-  try {
-    const safe = sanitizeFolderName(req.params.name)
-    if (!safe) throw new Error('폴더 이름이 올바르지 않습니다.')
-    const id = pickStr(req.body.id)
-    await deleteVideo(safe, id)
-    res.json({ ok: true })
-  } catch (err) {
-    res.status(400).json({ ok: false, message: (err as Error).message })
-  }
-})
+// ─── 영상 업로드 / 유튜브 ───────────────────────────────────────────────

-// multer 가 던지는 LIMIT_FILE_SIZE 같은 에러를 라우트 핸들러가 잡지 못해
-// 글로벌 에러 핸들러로 새서 stack trace 가 그대로 노출되던 문제를 막는다.
 function uploadSingle(fieldName: string) {
  const mw = upload.single(fieldName)
  return (req: Request, res: Response, next: NextFunction) => {
@@ -219,45 +231,37 @@ function uploadSingle(fieldName: string) {
  }
 }

-// 업로드: 단일 파일. multipart/form-data, fields: title, file
 opRouter.post(
-  '/op/folder/:name/video/upload',
+  ['/op/folder/:topName/video/upload', '/op/folder/:topName/:subName/video/upload'],
  requireAuth,
  uploadSingle('file'),
  async (req, res) => {
    try {
-      const safe = sanitizeFolderName(req.params.name)
-      if (!safe) throw new Error('폴더 이름이 올바르지 않습니다.')
+      const folder = getFolderByPath(collectFolderSegments(req.params))
+      if (!folder) throw new Error('폴더를 찾을 수 없습니다.')
      const file = req.file
      if (!file) throw new Error('파일이 없습니다.')
      const title = pickStr(req.body?.title).trim() || file.originalname
      const ext = (path.extname(file.originalname) || '.mp4').toLowerCase()
-      const videoId = newVideoId()
      const destName = `original${ext}`
-      await moveUploadIntoVideo(safe, videoId, file.path, destName)
-      const now = new Date().toISOString()
-      const meta = {
-        id: videoId,
+      const video = await createVideo({
+        folderId: folder.id,
        title,
        originalFile: destName,
-        editedFile: null,
-        durationSec: null,
-        sourceType: 'upload' as const,
-        sourceUrl: null,
-        trim: null,
-        createdAt: now,
-        updatedAt: now
-      }
-      await saveVideoMeta(safe, meta)
-      res.json({ ok: true, videoId, folder: safe })
+        sourceType: 'upload'
+      })
+      await moveUploadIntoVideoDir(video.id, file.path, destName)
+      res.json({ ok: true, videoId: video.id })
    } catch (err) {
      res.status(400).json({ ok: false, message: (err as Error).message })
    }
  }
 )

-// 유튜브 프로브: 다운받기 전에 길이/사이즈/예상시간/5분초과경고
-opRouter.post('/op/folder/:name/video/youtube/probe', requireAuth, async (req, res) => {
+opRouter.post(
+  ['/op/folder/:topName/video/youtube/probe', '/op/folder/:topName/:subName/video/youtube/probe'],
+  requireAuth,
+  async (req, res) => {
    try {
      const url = pickStr(req.body.url).trim()
      if (!url) throw new Error('URL 을 입력해 주세요.')
@@ -270,16 +274,20 @@ opRouter.post('/op/folder/:name/video/youtube/probe', requireAuth, async (req, r
      }
      res.status(400).json({ ok: false, message: (err as Error).message })
    }
-})
+  }
+)

-opRouter.post('/op/folder/:name/video/youtube/start', requireAuth, async (req, res) => {
+opRouter.post(
+  ['/op/folder/:topName/video/youtube/start', '/op/folder/:topName/:subName/video/youtube/start'],
+  requireAuth,
+  async (req, res) => {
    try {
-    const safe = sanitizeFolderName(req.params.name)
-    if (!safe) throw new Error('폴더 이름이 올바르지 않습니다.')
+      const folder = getFolderByPath(collectFolderSegments(req.params))
+      if (!folder) throw new Error('폴더를 찾을 수 없습니다.')
      const url = pickStr(req.body.url).trim()
      const title = pickStr(req.body.title).trim() || undefined
      if (!url) throw new Error('URL 을 입력해 주세요.')
-    const job = await startYoutubeDownload({ folder: safe, url, title })
+      const job = await startYoutubeDownload({ folderId: folder.id, url, title })
      res.json({ ok: true, jobId: job.id, videoId: job.videoId })
    } catch (err) {
      if (err instanceof YtDlpUnavailableError) {
@@ -288,11 +296,11 @@ opRouter.post('/op/folder/:name/video/youtube/start', requireAuth, async (req, r
      }
      res.status(400).json({ ok: false, message: (err as Error).message })
    }
-})
+  }
+)

 opRouter.get('/op/job/:id', requireAuth, (req, res) => {
-  // 폴링 응답이 304 로 캐싱되면 브라우저가 body 없는 응답을 돌려줘서
-  // 클라이언트의 r.json() 이 reject → 폴링이 중단된다. 항상 신선한 응답.
+  // 폴링 응답이 304 로 캐싱되면 클라이언트의 r.json() 이 reject → 폴링 중단된다.
  res.set('Cache-Control', 'no-store, no-cache, must-revalidate')
  res.set('Pragma', 'no-cache')
  const job = getJob(req.params.id)
@@ -303,12 +311,58 @@ opRouter.get('/op/job/:id', requireAuth, (req, res) => {
  res.json({ ok: true, job })
 })

-// 편집 저장: trim 정보를 받아 ffmpeg 로 edited.<ext> 생성. 원본은 그대로 보존.
-opRouter.post('/op/folder/:name/video/save', requireAuth, async (req, res) => {
+// ─── 영상 mutation (id 기반 — 전역 유일 ID) ─────────────────────────────
+
+opRouter.post('/op/videos/:id/rename', requireAuth, (req, res) => {
  try {
-    const safe = sanitizeFolderName(req.params.name)
-    if (!safe) throw new Error('폴더 이름이 올바르지 않습니다.')
-    const id = pickStr(req.body.id)
+    const id = req.params.id
+    const title = pickStr(req.body.title).trim()
+    if (!title) throw new Error('제목을 입력해 주세요.')
+    if (!getVideo(id)) throw new Error('영상을 찾을 수 없습니다.')
+    updateVideo(id, { title })
+    res.json({ ok: true })
+  } catch (err) {
+    res.status(400).json({ ok: false, message: (err as Error).message })
+  }
+})
+
+opRouter.post('/op/videos/:id/changeId', requireAuth, async (req, res) => {
+  try {
+    const oldId = req.params.id
+    const newId = pickStr(req.body.newId).trim()
+    if (!newId) throw new Error('새 ID 를 입력해 주세요.')
+    const video = await changeVideoId(oldId, newId)
+    res.json({ ok: true, video })
+  } catch (err) {
+    res.status(400).json({ ok: false, message: (err as Error).message })
+  }
+})
+
+/** 새 ID 가 사용 가능한지 미리 확인 (인풋 옆 실시간 표시용). */
+opRouter.get('/op/videos/idAvailable', requireAuth, (req, res) => {
+  const id = typeof req.query.id === 'string' ? req.query.id.trim() : ''
+  if (!id) {
+    res.json({ ok: true, available: false, reason: '비어 있음' })
+    return
+  }
+  const available = !videoIdExists(id)
+  res.json({ ok: true, available })
+})
+
+opRouter.post('/op/videos/:id/delete', requireAuth, async (req, res) => {
+  try {
+    await deleteVideo(req.params.id)
+    res.json({ ok: true })
+  } catch (err) {
+    res.status(400).json({ ok: false, message: (err as Error).message })
+  }
+})
+
+opRouter.post('/op/videos/:id/save', requireAuth, async (req, res) => {
+  try {
+    const id = req.params.id
+    const video = getVideo(id)
+    if (!video) throw new Error('영상을 찾을 수 없습니다.')
    const title = pickStr(req.body.title).trim()
    const startSec = Number(req.body.startSec ?? 0) || 0
    const endRaw = req.body.endSec
@@ -316,14 +370,14 @@ opRouter.post('/op/folder/:name/video/save', requireAuth, async (req, res) => {
      endRaw === null || endRaw === undefined || endRaw === ''
        ? null
        : Number(endRaw)
-    const meta = await loadVideoMeta(safe, id)
-    if (!meta) throw new Error('영상을 찾을 수 없습니다.')
-    if (title) meta.title = title
-    meta.trim = { startSec, endSec: endSec == null || Number.isNaN(endSec) ? null : endSec }
-    await saveVideoMeta(safe, meta)
+    const trim = {
+      startSec,
+      endSec: endSec == null || Number.isNaN(endSec) ? null : endSec
+    }
+    updateVideo(id, { trim, ...(title ? { title } : {}) })
    // ffmpeg 가 없으면 trim 정보만 저장하고 안내.
    try {
-      const outName = await applyTrimToVideo(safe, id, meta.trim)
+      const outName = await applyTrimToVideo(id, trim)
      res.json({ ok: true, editedFile: outName, note: '편집본 저장 완료' })
    } catch (err) {
      if (err instanceof FfmpegUnavailableError) {
@@ -340,3 +394,26 @@ opRouter.post('/op/folder/:name/video/save', requireAuth, async (req, res) => {
    res.status(400).json({ ok: false, message: (err as Error).message })
  }
 })
+
+// ─── 헬퍼 ─────────────────────────────────────────────────────────────
+
+function collectFolderSegments(params: Record<string, string | undefined>): string[] {
+  const out: string[] = []
+  if (params.topName) out.push(params.topName)
+  if (params.subName) out.push(params.subName)
+  return out
+}
+
+/** 폴더 ID → admin URL. 클라이언트가 form action 만들 때 미사용이면 제거 가능. */
+export function adminFolderUrl(folderId: number): string {
+  const names = folderPathNames(folderId)
+  return '/op/folder/' + names.map((s) => encodeURIComponent(s)).join('/')
+}
+
+/** 비디오 ID → 공개 공유 URL (/video/topName/[subName/]videoId). */
+export function videoShareUrl(videoId: string): string | null {
+  const v = getVideo(videoId)
+  if (!v) return null
+  const names = folderPathNames(v.folderId)
+  return '/video/' + [...names, videoId].map((s) => encodeURIComponent(s)).join('/')
+}
--- a/src/routes/public.ts
+++ b/src/routes/public.ts
@@ -1,84 +1,108 @@
 import { Router, type RequestHandler } from 'express'
-import path from 'node:path'
-import { promises as fs } from 'node:fs'
 import {
-  findVideoAnywhere,
-  folderPath,
-  listFolders,
-  listVideos,
-  loadVideoMeta,
-  sanitizeFolderName,
-  videoDir,
-  videoFileFsPath
-} from '../store.js'
+  getFolderByPath,
+  getVideo,
+  listChildFolders,
+  listTopFolders,
+  listVideosInFolder,
+  folderPathNames,
+  videoFileFsPath,
+  type Folder,
+  type Video
+} from '../storeDb.js'

 export const publicRouter = Router()

-publicRouter.get('/', async (_req, res, next) => {
+publicRouter.get('/', (_req, res, next) => {
  try {
-    const folders = await listFolders()
+    const folders = listTopFolders()
    res.render('index', { folders })
  } catch (err) {
    next(err)
  }
 })

-publicRouter.get('/folder/:name', async (req, res, next) => {
+/**
+ * 폴더 보기 (공개).
+ *  - /folder/:topName            — 최상위 폴더 (자식 폴더 + 영상 혼합 가능)
+ *  - /folder/:topName/:subName   — 서브폴더 (영상만)
+ */
+const folderViewHandler: RequestHandler = (req, res, next) => {
  try {
-    const safe = sanitizeFolderName(req.params.name)
-    if (!safe) {
+    const segments = collectFolderSegments(req.params)
+    const folder = getFolderByPath(segments)
+    if (!folder) {
      res.status(404).send('폴더를 찾을 수 없습니다.')
      return
    }
-    // 존재 확인
-    try {
-      await fs.access(folderPath(safe))
-    } catch {
-      res.status(404).send('폴더를 찾을 수 없습니다.')
-      return
-    }
-    const videos = await listVideos(safe)
-    res.render('folder', { folder: safe, videos, isAdmin: false })
+    const subFolders = folder.parentId === null ? listChildFolders(folder.id) : []
+    const videos = listVideosInFolder(folder.id)
+    res.render('folder', {
+      folder,
+      breadcrumb: folderPathNames(folder.id),
+      subFolders,
+      videos,
+      isAdmin: false,
+      isSubFolder: folder.parentId !== null
+    })
  } catch (err) {
    next(err)
  }
-})
+}
+publicRouter.get('/folder/:topName', folderViewHandler)
+publicRouter.get('/folder/:topName/:subName', folderViewHandler)

-publicRouter.get('/player/:videoId', async (req, res, next) => {
+/**
+ * 영상 보기 (공개).
+ *  - /video/:topName/:videoId
+ *  - /video/:topName/:subName/:videoId
+ *
+ * 경로의 마지막 세그먼트는 영상 ID. 앞쪽은 그 영상이 속한 폴더 경로와 일치해야 한다.
+ * (DB lookup 한 번이므로 path 가 ID 의 정합성 검증 역할도 함)
+ */
+const videoViewHandler: RequestHandler = (req, res, next) => {
  try {
-    const found = await findVideoAnywhere(req.params.videoId)
-    if (!found) {
+    const { folderSegments, videoId } = collectVideoSegments(req.params)
+    const video = getVideo(videoId)
+    if (!video) {
      res.status(404).send('영상을 찾을 수 없습니다.')
      return
    }
-    res.render('player', { folder: found.folder, video: found.meta })
+    const folderPath = folderPathNames(video.folderId)
+    if (!segmentsEqual(folderPath, folderSegments)) {
+      res.status(404).send('영상 경로가 일치하지 않습니다.')
+      return
+    }
+    res.render('player', { video, breadcrumb: folderPath })
  } catch (err) {
    next(err)
  }
-})
+}
+publicRouter.get('/video/:topName/:videoId', videoViewHandler)
+publicRouter.get('/video/:topName/:subName/:videoId', videoViewHandler)

 /**
- * 영상 파일 스트리밍.
- * - 짧은 외부 공유용 경로: /file/video/:videoId
- * - 기존 경로: /api/video/:videoId/file (호환용으로 유지)
- * - ?edited=0 이면 원본을 강제하고, 기본은 편집본 있으면 편집본.
+ * 영상 파일 스트리밍 (짧은 ID-only URL — 외부 공유 호환용).
+ *  - GET /file/video/:videoId
+ *  - GET /api/video/:videoId/file (legacy alias)
+ * ?edited=0 이면 원본을 강제, 기본은 편집본 있으면 편집본.
 */
-const streamVideoHandler: RequestHandler = async (req, res, next) => {
+const streamVideoHandler: RequestHandler = (req, res, next) => {
  try {
-    const found = await findVideoAnywhere(req.params.videoId)
-    if (!found) {
+    const video = getVideo(req.params.videoId)
+    if (!video) {
      res.status(404).end()
      return
    }
    const editedParam = typeof req.query.edited === 'string' ? req.query.edited : ''
    const wantOriginal = editedParam === '0' || editedParam === 'false'
    const fileName =
-      !wantOriginal && found.meta.editedFile ? found.meta.editedFile : found.meta.originalFile
+      !wantOriginal && video.editedFile ? video.editedFile : video.originalFile
    if (!fileName || fileName.includes('%(ext)s')) {
      res.status(404).end()
      return
    }
-    const fsPath = videoFileFsPath(found.folder, found.meta.id, fileName)
+    const fsPath = videoFileFsPath(video.id, fileName)
    res.sendFile(fsPath)
  } catch (err) {
    next(err)
@@ -87,16 +111,49 @@ const streamVideoHandler: RequestHandler = async (req, res, next) => {
 publicRouter.get('/file/video/:videoId', streamVideoHandler)
 publicRouter.get('/api/video/:videoId/file', streamVideoHandler)

-/** 비디오 메타 조회 (플레이어/관리자 양쪽에서 사용) */
-publicRouter.get('/api/video/:videoId', async (req, res, next) => {
+/** 비디오 메타 조회 (플레이어/관리자 양쪽에서 사용). */
+publicRouter.get('/api/video/:videoId', (req, res, next) => {
  try {
-    const found = await findVideoAnywhere(req.params.videoId)
-    if (!found) {
+    const video = getVideo(req.params.videoId)
+    if (!video) {
      res.status(404).json({ ok: false, message: '영상을 찾을 수 없습니다.' })
      return
    }
-    res.json({ ok: true, folder: found.folder, video: found.meta })
+    res.json({
+      ok: true,
+      video,
+      breadcrumb: folderPathNames(video.folderId)
+    })
  } catch (err) {
    next(err)
  }
 })
+
+// ─── 헬퍼 ─────────────────────────────────────────────────────────────
+
+function collectFolderSegments(params: Record<string, string | undefined>): string[] {
+  const out: string[] = []
+  if (params.topName) out.push(params.topName)
+  if (params.subName) out.push(params.subName)
+  return out
+}
+
+function collectVideoSegments(params: Record<string, string | undefined>): {
+  folderSegments: string[]
+  videoId: string
+} {
+  const folderSegments: string[] = []
+  if (params.topName) folderSegments.push(params.topName)
+  if (params.subName) folderSegments.push(params.subName)
+  return { folderSegments, videoId: params.videoId ?? '' }
+}
+
+function segmentsEqual(a: string[], b: string[]): boolean {
+  if (a.length !== b.length) return false
+  for (let i = 0; i < a.length; i++) {
+    if (a[i] !== b[i]) return false
+  }
+  return true
+}
+
+export type { Folder, Video }
--- a/src/store.ts
+++ b/src/store.ts
@@ -1,31 +1,12 @@
-import { promises as fs, createReadStream, createWriteStream } from 'node:fs'
-import path from 'node:path'
-import { randomUUID } from 'node:crypto'
-import { foldersDir, accountJsonPath } from './paths.js'
+import { promises as fs } from 'node:fs'
+import { accountJsonPath } from './paths.js'

 export interface Account {
  id: string
  password: string
 }

-export interface VideoTrim {
-  startSec: number
-  endSec: number | null  // null = until end
-}
-
-export interface VideoMeta {
-  id: string
-  title: string
-  originalFile: string   // relative to <folder>/<id>/
-  editedFile: string | null
-  durationSec: number | null
-  sourceType: 'upload' | 'youtube'
-  sourceUrl: string | null
-  trim: VideoTrim | null
-  createdAt: string
-  updatedAt: string
-}
-
+/** account.json 에서 로그인 계정 목록을 읽는다. (나머지 파일 기반 저장소는 storeDb.ts 로 이전됨.) */
 export async function readAccounts(): Promise<Account[]> {
  try {
    const raw = await fs.readFile(accountJsonPath, 'utf8')
@@ -40,181 +21,3 @@ export async function readAccounts(): Promise<Account[]> {
    throw err
  }
 }
-
-// 폴더/영상 이름에 사용 가능한 문자만 허용. 경로 탈출 방지.
-const SAFE_NAME = /^[\p{L}\p{N}_\- ]+$/u
-
-export function sanitizeFolderName(raw: string): string {
-  const trimmed = (raw || '').trim()
-  if (trimmed.length === 0 || trimmed.length > 80) return ''
-  if (!SAFE_NAME.test(trimmed)) return ''
-  if (trimmed === '.' || trimmed === '..') return ''
-  return trimmed
-}
-
-export function isSafeVideoId(id: string): boolean {
-  return /^[a-zA-Z0-9_-]{8,64}$/.test(id)
-}
-
-export async function ensureFoldersDir(): Promise<void> {
-  await fs.mkdir(foldersDir, { recursive: true })
-}
-
-export async function listFolders(): Promise<string[]> {
-  await ensureFoldersDir()
-  const entries = await fs.readdir(foldersDir, { withFileTypes: true })
-  return entries
-    .filter((e) => e.isDirectory())
-    .map((e) => e.name)
-    .filter((name) => sanitizeFolderName(name).length > 0)
-    .sort((a, b) => a.localeCompare(b, 'ko'))
-}
-
-export async function createFolder(name: string): Promise<string> {
-  const safe = sanitizeFolderName(name)
-  if (!safe) throw new Error('폴더 이름이 올바르지 않습니다.')
-  const target = path.join(foldersDir, safe)
-  await fs.mkdir(target, { recursive: false }).catch((err) => {
-    if (err.code === 'EEXIST') throw new Error('이미 존재하는 폴더입니다.')
-    throw err
-  })
-  return safe
-}
-
-export async function renameFolder(oldName: string, newName: string): Promise<string> {
-  const oldSafe = sanitizeFolderName(oldName)
-  const newSafe = sanitizeFolderName(newName)
-  if (!oldSafe || !newSafe) throw new Error('폴더 이름이 올바르지 않습니다.')
-  if (oldSafe === newSafe) return oldSafe
-  const from = path.join(foldersDir, oldSafe)
-  const to = path.join(foldersDir, newSafe)
-  try {
-    await fs.access(to)
-    throw new Error('이미 존재하는 폴더입니다.')
-  } catch (err) {
-    if ((err as NodeJS.ErrnoException).code !== 'ENOENT') throw err
-  }
-  await fs.rename(from, to)
-  return newSafe
-}
-
-export async function deleteFolder(name: string): Promise<void> {
-  const safe = sanitizeFolderName(name)
-  if (!safe) throw new Error('폴더 이름이 올바르지 않습니다.')
-  const target = path.join(foldersDir, safe)
-  await fs.rm(target, { recursive: true, force: true })
-}
-
-export function folderPath(name: string): string {
-  const safe = sanitizeFolderName(name)
-  if (!safe) throw new Error('폴더 이름이 올바르지 않습니다.')
-  return path.join(foldersDir, safe)
-}
-
-export function videoDir(folder: string, videoId: string): string {
-  if (!isSafeVideoId(videoId)) throw new Error('비디오 ID가 올바르지 않습니다.')
-  return path.join(folderPath(folder), videoId)
-}
-
-export function videoMetaPath(folder: string, videoId: string): string {
-  return path.join(videoDir(folder, videoId), 'meta.json')
-}
-
-export async function listVideos(folder: string): Promise<VideoMeta[]> {
-  const dir = folderPath(folder)
-  try {
-    const entries = await fs.readdir(dir, { withFileTypes: true })
-    const metas: VideoMeta[] = []
-    for (const entry of entries) {
-      if (!entry.isDirectory()) continue
-      if (!isSafeVideoId(entry.name)) continue
-      const meta = await loadVideoMeta(folder, entry.name).catch(() => null)
-      if (meta) metas.push(meta)
-    }
-    metas.sort((a, b) => (b.createdAt < a.createdAt ? -1 : 1))
-    return metas
-  } catch (err) {
-    if ((err as NodeJS.ErrnoException).code === 'ENOENT') return []
-    throw err
-  }
-}
-
-export async function loadVideoMeta(folder: string, videoId: string): Promise<VideoMeta | null> {
-  try {
-    const raw = await fs.readFile(videoMetaPath(folder, videoId), 'utf8')
-    return JSON.parse(raw) as VideoMeta
-  } catch (err) {
-    if ((err as NodeJS.ErrnoException).code === 'ENOENT') return null
-    throw err
-  }
-}
-
-export async function findVideoAnywhere(
-  videoId: string
-): Promise<{ folder: string; meta: VideoMeta } | null> {
-  if (!isSafeVideoId(videoId)) return null
-  const folders = await listFolders()
-  for (const folder of folders) {
-    const meta = await loadVideoMeta(folder, videoId).catch(() => null)
-    if (meta) return { folder, meta }
-  }
-  return null
-}
-
-export async function saveVideoMeta(folder: string, meta: VideoMeta): Promise<void> {
-  const dir = videoDir(folder, meta.id)
-  await fs.mkdir(dir, { recursive: true })
-  meta.updatedAt = new Date().toISOString()
-  await fs.writeFile(videoMetaPath(folder, meta.id), JSON.stringify(meta, null, 2))
-}
-
-export async function deleteVideo(folder: string, videoId: string): Promise<void> {
-  const dir = videoDir(folder, videoId)
-  await fs.rm(dir, { recursive: true, force: true })
-}
-
-export function newVideoId(): string {
-  // URL-safe 22-char id (uuid 압축).
-  return randomUUID().replace(/-/g, '').slice(0, 24)
-}
-
-export function videoFileFsPath(folder: string, videoId: string, rel: string): string {
-  // rel 은 meta 에 저장된 파일명. 경로 탈출 방지.
-  if (rel.includes('/') || rel.includes('\\') || rel.includes('..')) {
-    throw new Error('잘못된 파일 경로입니다.')
-  }
-  return path.join(videoDir(folder, videoId), rel)
-}
-
-/** 업로드 임시 파일을 비디오 디렉토리로 이동. */
-export async function moveUploadIntoVideo(
-  folder: string,
-  videoId: string,
-  tmpFile: string,
-  destName: string
-): Promise<void> {
-  if (destName.includes('/') || destName.includes('\\') || destName.includes('..')) {
-    throw new Error('잘못된 파일명입니다.')
-  }
-  const dir = videoDir(folder, videoId)
-  await fs.mkdir(dir, { recursive: true })
-  const target = path.join(dir, destName)
-  try {
-    await fs.rename(tmpFile, target)
-  } catch (err) {
-    if ((err as NodeJS.ErrnoException).code === 'EXDEV') {
-      // 다른 디바이스에 있으면 copy + unlink
-      await new Promise<void>((resolve, reject) => {
-        const r = createReadStream(tmpFile)
-        const w = createWriteStream(target)
-        r.on('error', reject)
-        w.on('error', reject)
-        w.on('close', () => resolve())
-        r.pipe(w)
-      })
-      await fs.unlink(tmpFile).catch(() => undefined)
-    } else {
-      throw err
-    }
-  }
-}
--- a/src/storeDb.ts
+++ b/src/storeDb.ts
@@ -0,0 +1,524 @@
+/**
+ * DB(SQLite) 기반 폴더/영상 CRUD + 디스크 동기화 레이어.
+ *
+ * 디스크 레이아웃 (변경 없음):
+ *   data/folders/{topName}/[{subName}/]{videoId}/...
+ *
+ * DB 가 source of truth. 변경 흐름:
+ *   1) 검증 (이름/ID/깊이/존재여부)
+ *   2) DB UPDATE/INSERT/DELETE
+ *   3) 디스크 동기화 (mkdir / rename / rm)
+ *   4) 실패 시 DB 롤백 (사용 가능한 경우)
+ *
+ * DB → 디스크 순서로 가는 이유: DB 가 UNIQUE 등 제약을 검사해 주므로 충돌을 일찍 잡고
+ * 디스크 작업으로 안 넘어간다. 디스크 작업이 실패하면 DB 변경을 되돌린다.
+ */
+import { promises as fsp } from 'node:fs'
+import path from 'node:path'
+import { randomUUID } from 'node:crypto'
+import { getDb } from './db.js'
+import { foldersDir } from './paths.js'
+
+// ─── 검증 ──────────────────────────────────────────────────────────────
+
+const SAFE_NAME = /^[\p{L}\p{N}_\- ]+$/u
+const SAFE_VIDEO_ID = /^[a-zA-Z0-9_-]{1,64}$/
+
+export function sanitizeFolderName(raw: string): string {
+  const trimmed = (raw || '').trim()
+  if (!trimmed || trimmed.length > 80) return ''
+  if (trimmed === '.' || trimmed === '..') return ''
+  if (!SAFE_NAME.test(trimmed)) return ''
+  return trimmed
+}
+
+export function isSafeVideoId(id: string): boolean {
+  return typeof id === 'string' && SAFE_VIDEO_ID.test(id)
+}
+
+export function newRandomVideoId(): string {
+  // URL-safe 24-char id (uuid 압축).
+  return randomUUID().replace(/-/g, '').slice(0, 24)
+}
+
+// ─── 타입 ──────────────────────────────────────────────────────────────
+
+export interface Folder {
+  id: number
+  parentId: number | null
+  name: string
+  position: number
+  createdAt: string
+  updatedAt: string
+}
+
+export interface VideoTrim {
+  startSec: number
+  endSec: number | null
+}
+
+export interface Video {
+  id: string
+  folderId: number
+  title: string
+  originalFile: string
+  editedFile: string | null
+  durationSec: number | null
+  sourceType: 'upload' | 'youtube'
+  sourceUrl: string | null
+  trim: VideoTrim | null
+  position: number
+  createdAt: string
+  updatedAt: string
+}
+
+interface FolderRow {
+  id: number
+  parent_id: number | null
+  name: string
+  position: number
+  created_at: string
+  updated_at: string
+}
+
+interface VideoRow {
+  id: string
+  folder_id: number
+  title: string
+  original_file: string
+  edited_file: string | null
+  duration_sec: number | null
+  source_type: 'upload' | 'youtube'
+  source_url: string | null
+  trim_start_sec: number | null
+  trim_end_sec: number | null
+  position: number
+  created_at: string
+  updated_at: string
+}
+
+function rowToFolder(r: FolderRow): Folder {
+  return {
+    id: r.id,
+    parentId: r.parent_id,
+    name: r.name,
+    position: r.position,
+    createdAt: r.created_at,
+    updatedAt: r.updated_at
+  }
+}
+
+function rowToVideo(r: VideoRow): Video {
+  const hasTrim = r.trim_start_sec !== null || r.trim_end_sec !== null
+  return {
+    id: r.id,
+    folderId: r.folder_id,
+    title: r.title,
+    originalFile: r.original_file,
+    editedFile: r.edited_file,
+    durationSec: r.duration_sec,
+    sourceType: r.source_type,
+    sourceUrl: r.source_url,
+    trim: hasTrim
+      ? { startSec: r.trim_start_sec ?? 0, endSec: r.trim_end_sec }
+      : null,
+    position: r.position,
+    createdAt: r.created_at,
+    updatedAt: r.updated_at
+  }
+}
+
+// ─── 폴더 조회 ─────────────────────────────────────────────────────────
+
+export function listTopFolders(): Folder[] {
+  const rows = getDb()
+    .prepare(
+      `SELECT * FROM folders WHERE parent_id IS NULL ORDER BY position, name`
+    )
+    .all() as FolderRow[]
+  return rows.map(rowToFolder)
+}
+
+export function listChildFolders(parentId: number): Folder[] {
+  const rows = getDb()
+    .prepare(`SELECT * FROM folders WHERE parent_id = ? ORDER BY position, name`)
+    .all(parentId) as FolderRow[]
+  return rows.map(rowToFolder)
+}
+
+export function getFolder(id: number): Folder | null {
+  const r = getDb()
+    .prepare(`SELECT * FROM folders WHERE id = ?`)
+    .get(id) as FolderRow | undefined
+  return r ? rowToFolder(r) : null
+}
+
+export function getTopFolderByName(name: string): Folder | null {
+  const safe = sanitizeFolderName(name)
+  if (!safe) return null
+  const r = getDb()
+    .prepare(`SELECT * FROM folders WHERE parent_id IS NULL AND name = ?`)
+    .get(safe) as FolderRow | undefined
+  return r ? rowToFolder(r) : null
+}
+
+export function getChildFolderByName(parentId: number, name: string): Folder | null {
+  const safe = sanitizeFolderName(name)
+  if (!safe) return null
+  const r = getDb()
+    .prepare(`SELECT * FROM folders WHERE parent_id = ? AND name = ?`)
+    .get(parentId, safe) as FolderRow | undefined
+  return r ? rowToFolder(r) : null
+}
+
+/** URL 경로 [topName] 또는 [topName, subName] → 폴더 1건. 못 찾으면 null. */
+export function getFolderByPath(names: string[]): Folder | null {
+  if (names.length === 0 || names.length > 2) return null
+  const top = getTopFolderByName(names[0])
+  if (!top) return null
+  if (names.length === 1) return top
+  return getChildFolderByName(top.id, names[1])
+}
+
+/** 폴더 → 디스크 경로 (parent 까지 거슬러 올라가 이름 join). */
+export function folderDiskPath(folderId: number): string {
+  const names = folderPathNames(folderId)
+  return path.join(foldersDir, ...names)
+}
+
+/** 폴더 → URL 경로 세그먼트 배열 (인코딩 전). */
+export function folderPathNames(folderId: number): string[] {
+  const names: string[] = []
+  let cur: Folder | null = getFolder(folderId)
+  while (cur) {
+    names.unshift(cur.name)
+    cur = cur.parentId !== null ? getFolder(cur.parentId) : null
+  }
+  return names
+}
+
+// ─── 폴더 변경 ─────────────────────────────────────────────────────────
+
+export async function createFolder(input: {
+  name: string
+  parentId: number | null
+}): Promise<Folder> {
+  const safe = sanitizeFolderName(input.name)
+  if (!safe) throw new Error('폴더 이름이 올바르지 않습니다.')
+  // 깊이 검사: 부모가 이미 서브폴더면 손자 폴더는 만들 수 없다 (최대 2단계).
+  if (input.parentId !== null) {
+    const parent = getFolder(input.parentId)
+    if (!parent) throw new Error('상위 폴더를 찾을 수 없습니다.')
+    if (parent.parentId !== null) {
+      throw new Error('서브폴더 안에는 폴더를 만들 수 없습니다.')
+    }
+  }
+  const now = new Date().toISOString()
+  const db = getDb()
+  // position = 현재 형제 개수 (끝에 추가)
+  const siblings = (db
+    .prepare(
+      input.parentId === null
+        ? `SELECT COUNT(*) as c FROM folders WHERE parent_id IS NULL`
+        : `SELECT COUNT(*) as c FROM folders WHERE parent_id = ?`
+    )
+    .get(...(input.parentId === null ? [] : [input.parentId])) as { c: number }).c
+
+  let info
+  try {
+    info = db
+      .prepare(
+        `INSERT INTO folders (parent_id, name, position, created_at, updated_at)
+         VALUES (?, ?, ?, ?, ?)`
+      )
+      .run(input.parentId, safe, siblings, now, now)
+  } catch (err) {
+    if ((err as Error).message.includes('UNIQUE')) {
+      throw new Error('이미 존재하는 폴더입니다.')
+    }
+    throw err
+  }
+  const folderId = Number(info.lastInsertRowid)
+  // 디스크 디렉토리 생성 (이미 있을 수 있음 — 마이그레이션 케이스).
+  const diskPath = folderDiskPath(folderId)
+  try {
+    await fsp.mkdir(diskPath, { recursive: true })
+  } catch (err) {
+    // 디스크 실패 시 DB 롤백.
+    db.prepare(`DELETE FROM folders WHERE id = ?`).run(folderId)
+    throw err
+  }
+  return getFolder(folderId)!
+}
+
+export async function renameFolder(folderId: number, newName: string): Promise<Folder> {
+  const folder = getFolder(folderId)
+  if (!folder) throw new Error('폴더를 찾을 수 없습니다.')
+  const safe = sanitizeFolderName(newName)
+  if (!safe) throw new Error('새 폴더 이름이 올바르지 않습니다.')
+  if (safe === folder.name) return folder
+
+  const oldDisk = folderDiskPath(folderId)
+  const db = getDb()
+  try {
+    db.prepare(`UPDATE folders SET name = ?, updated_at = ? WHERE id = ?`).run(
+      safe,
+      new Date().toISOString(),
+      folderId
+    )
+  } catch (err) {
+    if ((err as Error).message.includes('UNIQUE')) {
+      throw new Error('이미 존재하는 폴더 이름입니다.')
+    }
+    throw err
+  }
+  const newDisk = folderDiskPath(folderId)
+  try {
+    await fsp.rename(oldDisk, newDisk)
+  } catch (err) {
+    // ENOENT (디스크 디렉토리가 없는 경우) 는 무시하고 비어있는 새 디렉토리 생성.
+    if ((err as NodeJS.ErrnoException).code === 'ENOENT') {
+      await fsp.mkdir(newDisk, { recursive: true })
+    } else {
+      // 디스크 rename 실패 → DB 롤백
+      db.prepare(`UPDATE folders SET name = ? WHERE id = ?`).run(folder.name, folderId)
+      throw err
+    }
+  }
+  return getFolder(folderId)!
+}
+
+export async function deleteFolder(folderId: number): Promise<void> {
+  const folder = getFolder(folderId)
+  if (!folder) return // idempotent
+  const diskPath = folderDiskPath(folderId)
+  // DB CASCADE 가 자식 폴더/영상까지 모두 삭제.
+  getDb().prepare(`DELETE FROM folders WHERE id = ?`).run(folderId)
+  await fsp.rm(diskPath, { recursive: true, force: true })
+}
+
+// ─── 영상 조회 ─────────────────────────────────────────────────────────
+
+export function getVideo(id: string): Video | null {
+  if (!isSafeVideoId(id)) return null
+  const r = getDb()
+    .prepare(`SELECT * FROM videos WHERE id = ?`)
+    .get(id) as VideoRow | undefined
+  return r ? rowToVideo(r) : null
+}
+
+export function listVideosInFolder(folderId: number): Video[] {
+  const rows = getDb()
+    .prepare(
+      `SELECT * FROM videos WHERE folder_id = ? ORDER BY position, created_at DESC`
+    )
+    .all(folderId) as VideoRow[]
+  return rows.map(rowToVideo)
+}
+
+export function videoIdExists(id: string): boolean {
+  if (!isSafeVideoId(id)) return false
+  const r = getDb()
+    .prepare(`SELECT 1 FROM videos WHERE id = ?`)
+    .get(id)
+  return !!r
+}
+
+/** 영상 → 디스크 디렉토리 (폴더 경로 + videoId). */
+export function videoDiskDir(videoId: string): string {
+  const v = getVideo(videoId)
+  if (!v) throw new Error('영상을 찾을 수 없습니다.')
+  return path.join(folderDiskPath(v.folderId), v.id)
+}
+
+/** 영상 → 공유 URL 의 경로 부분 (인코딩 전 세그먼트). */
+export function videoPathNames(videoId: string): string[] | null {
+  const v = getVideo(videoId)
+  if (!v) return null
+  return [...folderPathNames(v.folderId), v.id]
+}
+
+/** 영상 디렉토리 내 파일의 절대 경로. 경로 탈출 방지. */
+export function videoFileFsPath(videoId: string, rel: string): string {
+  if (!rel || rel.includes('/') || rel.includes('\\') || rel.includes('..')) {
+    throw new Error('잘못된 파일 경로입니다.')
+  }
+  return path.join(videoDiskDir(videoId), rel)
+}
+
+// ─── 영상 변경 ─────────────────────────────────────────────────────────
+
+export interface CreateVideoInput {
+  id?: string                       // 미지정 시 랜덤
+  folderId: number
+  title: string
+  originalFile: string              // 디렉토리 안 상대 경로 (또는 'original.%(ext)s' 같은 yt-dlp 임시 패턴)
+  sourceType: 'upload' | 'youtube'
+  sourceUrl?: string | null
+}
+
+export async function createVideo(input: CreateVideoInput): Promise<Video> {
+  const folder = getFolder(input.folderId)
+  if (!folder) throw new Error('폴더를 찾을 수 없습니다.')
+  let id = input.id ?? newRandomVideoId()
+  if (!isSafeVideoId(id)) throw new Error('영상 ID 가 올바르지 않습니다.')
+  if (videoIdExists(id)) throw new Error('이미 사용 중인 영상 ID 입니다.')
+
+  const now = new Date().toISOString()
+  const db = getDb()
+  // position = 현재 폴더 안 영상 개수 (끝에 추가)
+  const count = (db
+    .prepare(`SELECT COUNT(*) as c FROM videos WHERE folder_id = ?`)
+    .get(input.folderId) as { c: number }).c
+  db.prepare(
+    `INSERT INTO videos
+       (id, folder_id, title, original_file, edited_file, duration_sec,
+        source_type, source_url, trim_start_sec, trim_end_sec,
+        position, created_at, updated_at)
+     VALUES (?, ?, ?, ?, NULL, NULL, ?, ?, NULL, NULL, ?, ?, ?)`
+  ).run(
+    id,
+    input.folderId,
+    input.title,
+    input.originalFile,
+    input.sourceType,
+    input.sourceUrl ?? null,
+    count,
+    now,
+    now
+  )
+  // 디스크 디렉토리 생성
+  const diskDir = path.join(folderDiskPath(input.folderId), id)
+  try {
+    await fsp.mkdir(diskDir, { recursive: true })
+  } catch (err) {
+    db.prepare(`DELETE FROM videos WHERE id = ?`).run(id)
+    throw err
+  }
+  return getVideo(id)!
+}
+
+export async function changeVideoId(oldId: string, newId: string): Promise<Video> {
+  if (!isSafeVideoId(newId)) throw new Error('새 영상 ID 가 올바르지 않습니다.')
+  if (oldId === newId) {
+    const v = getVideo(oldId)
+    if (!v) throw new Error('영상을 찾을 수 없습니다.')
+    return v
+  }
+  const current = getVideo(oldId)
+  if (!current) throw new Error('영상을 찾을 수 없습니다.')
+  if (videoIdExists(newId)) throw new Error('이미 사용 중인 영상 ID 입니다.')
+
+  const oldDir = path.join(folderDiskPath(current.folderId), current.id)
+  const newDir = path.join(folderDiskPath(current.folderId), newId)
+  const db = getDb()
+  try {
+    db.prepare(`UPDATE videos SET id = ?, updated_at = ? WHERE id = ?`).run(
+      newId,
+      new Date().toISOString(),
+      oldId
+    )
+  } catch (err) {
+    if ((err as Error).message.includes('UNIQUE')) {
+      throw new Error('이미 사용 중인 영상 ID 입니다.')
+    }
+    throw err
+  }
+  try {
+    await fsp.rename(oldDir, newDir)
+  } catch (err) {
+    if ((err as NodeJS.ErrnoException).code === 'ENOENT') {
+      // 디스크에 디렉토리가 없으면 빈 디렉토리 생성 (메타만 있는 케이스).
+      await fsp.mkdir(newDir, { recursive: true })
+    } else {
+      db.prepare(`UPDATE videos SET id = ? WHERE id = ?`).run(oldId, newId)
+      throw err
+    }
+  }
+  return getVideo(newId)!
+}
+
+export interface UpdateVideoPatch {
+  title?: string
+  originalFile?: string
+  editedFile?: string | null
+  durationSec?: number | null
+  sourceUrl?: string | null
+  trim?: VideoTrim | null
+}
+
+export function updateVideo(id: string, patch: UpdateVideoPatch): Video {
+  const current = getVideo(id)
+  if (!current) throw new Error('영상을 찾을 수 없습니다.')
+
+  const fields: string[] = []
+  const params: unknown[] = []
+  if (patch.title !== undefined) {
+    fields.push('title = ?')
+    params.push(patch.title)
+  }
+  if (patch.originalFile !== undefined) {
+    fields.push('original_file = ?')
+    params.push(patch.originalFile)
+  }
+  if (patch.editedFile !== undefined) {
+    fields.push('edited_file = ?')
+    params.push(patch.editedFile)
+  }
+  if (patch.durationSec !== undefined) {
+    fields.push('duration_sec = ?')
+    params.push(patch.durationSec)
+  }
+  if (patch.sourceUrl !== undefined) {
+    fields.push('source_url = ?')
+    params.push(patch.sourceUrl)
+  }
+  if (patch.trim !== undefined) {
+    if (patch.trim === null) {
+      fields.push('trim_start_sec = NULL', 'trim_end_sec = NULL')
+    } else {
+      fields.push('trim_start_sec = ?', 'trim_end_sec = ?')
+      params.push(patch.trim.startSec, patch.trim.endSec)
+    }
+  }
+  if (fields.length === 0) return current
+  fields.push('updated_at = ?')
+  params.push(new Date().toISOString())
+  params.push(id)
+  getDb().prepare(`UPDATE videos SET ${fields.join(', ')} WHERE id = ?`).run(...params)
+  return getVideo(id)!
+}
+
+export async function deleteVideo(id: string): Promise<void> {
+  const v = getVideo(id)
+  if (!v) return
+  const diskDir = path.join(folderDiskPath(v.folderId), v.id)
+  getDb().prepare(`DELETE FROM videos WHERE id = ?`).run(id)
+  await fsp.rm(diskDir, { recursive: true, force: true })
+}
+
+// ─── 업로드 임시 파일 → 영상 디렉토리 이동 ─────────────────────────────
+
+export async function moveUploadIntoVideoDir(
+  videoId: string,
+  tmpFile: string,
+  destName: string
+): Promise<void> {
+  if (!destName || destName.includes('/') || destName.includes('\\') || destName.includes('..')) {
+    throw new Error('잘못된 파일명입니다.')
+  }
+  const dir = videoDiskDir(videoId)
+  await fsp.mkdir(dir, { recursive: true })
+  const target = path.join(dir, destName)
+  try {
+    await fsp.rename(tmpFile, target)
+  } catch (err) {
+    if ((err as NodeJS.ErrnoException).code === 'EXDEV') {
+      // 다른 디바이스면 copyFile + unlink
+      await fsp.copyFile(tmpFile, target)
+      await fsp.unlink(tmpFile).catch(() => undefined)
+    } else {
+      throw err
+    }
+  }
+}
--- a/src/youtube.ts
+++ b/src/youtube.ts
@@ -4,13 +4,12 @@ import path from 'node:path'
 import { jobsDir, projectRoot } from './paths.js'
 import { upscaleOriginalTo60Fps } from './editor.js'
 import {
-  loadVideoMeta,
-  newVideoId,
-  saveVideoMeta,
-  sanitizeFolderName,
-  videoDir,
-  type VideoMeta
-} from './store.js'
+  createVideo,
+  getFolder,
+  getVideo,
+  updateVideo,
+  videoDiskDir
+} from './storeDb.js'

 export class YtDlpUnavailableError extends Error {
  constructor(message?: string) {
@@ -94,7 +93,7 @@ export type JobStatus = 'queued' | 'downloading' | 'done' | 'error'

 export interface DownloadJob {
  id: string
-  folder: string
+  folderId: number
  videoId: string
  url: string
  status: JobStatus
@@ -122,39 +121,33 @@ export function listActiveJobs(): DownloadJob[] {
 }

 export interface StartDownloadOpts {
-  folder: string
+  folderId: number
  url: string
  title?: string
+  /** 호출자가 영상 ID 를 지정 (플레이리스트 일괄 등록용). 미지정 시 랜덤 생성. */
+  videoId?: string
 }

 /** 백그라운드 yt-dlp 다운로드를 시작. videoId 도 함께 생성/저장한다. */
 export async function startYoutubeDownload(opts: StartDownloadOpts): Promise<DownloadJob> {
-  const safeFolder = sanitizeFolderName(opts.folder)
-  if (!safeFolder) throw new Error('폴더 이름이 올바르지 않습니다.')
+  const folder = getFolder(opts.folderId)
+  if (!folder) throw new Error('폴더를 찾을 수 없습니다.')
  const bin = getYtDlpPath() // 없으면 즉시 던짐
-  const videoId = newVideoId()
-  const dir = videoDir(safeFolder, videoId)
-  await fs.mkdir(dir, { recursive: true })

-  const now = new Date().toISOString()
-  const meta: VideoMeta = {
-    id: videoId,
+  const video = await createVideo({
+    id: opts.videoId,
+    folderId: opts.folderId,
    title: opts.title?.trim() || '제목 없음',
    originalFile: 'original.%(ext)s', // 다운로드 완료 후 실제 확장자로 갱신
-    editedFile: null,
-    durationSec: null,
    sourceType: 'youtube',
-    sourceUrl: opts.url,
-    trim: null,
-    createdAt: now,
-    updatedAt: now
-  }
-  await saveVideoMeta(safeFolder, meta)
+    sourceUrl: opts.url
+  })

+  const now = new Date().toISOString()
  const job: DownloadJob = {
-    id: newVideoId(),
-    folder: safeFolder,
-    videoId,
+    id: 'job-' + Math.random().toString(36).slice(2, 14),
+    folderId: opts.folderId,
+    videoId: video.id,
    url: opts.url,
    status: 'queued',
    progress: 0,
@@ -180,7 +173,7 @@ async function runJob(job: DownloadJob, bin: string): Promise<void> {
  job.message = '다운로드 시작'
  await persistJob(job)

-  const dir = videoDir(job.folder, job.videoId)
+  const dir = videoDiskDir(job.videoId)
  // yt-dlp 가 다운로드 후 결정한 실제 파일명을 알려주도록 --print after_move:filepath
  // 진행률은 --newline + --progress-template 으로 stdout 줄 단위 파싱.
  const args = [
@@ -288,10 +281,9 @@ async function runJob(job: DownloadJob, bin: string): Promise<void> {
        console.error('[youtube] 60fps 후처리 실패:', err)
      }

-      const meta = await loadVideoMeta(job.folder, job.videoId)
+      const meta = getVideo(job.videoId)
      if (meta) {
-        meta.originalFile = finalName
-        await saveVideoMeta(job.folder, meta)
+        updateVideo(job.videoId, { originalFile: finalName })
      }
      job.progress = 100
      job.status = 'done'
--- a/views/folder.ejs
+++ b/views/folder.ejs
@@ -3,7 +3,7 @@
 <head>
  <meta charset="utf-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1" />
-  <title><%= folder %> · 비디오 사이트</title>
+  <title><%= folder.name %> · 비디오 사이트</title>
  <link rel="stylesheet" href="/static/styles.css" />
 </head>
 <body class="siteBody">
@@ -15,41 +15,51 @@
    <a class="secondaryButton" href="/op">관리자</a>
  </header>

+  <%
+    // 현재 폴더까지의 경로 prefix (영상/하위폴더 URL 조립용)
+    var folderPathEnc = breadcrumb.map(function (s) { return encodeURIComponent(s) }).join('/')
+    var parentHref = isSubFolder ? '/folder/' + encodeURIComponent(breadcrumb[0]) : '/'
+    var parentLabel = isSubFolder ? '← ' + breadcrumb[0] : '← 폴더 목록'
+  %>
+
  <main class="pageWrap">
    <section class="hero">
-      <a class="muted" href="/">← 폴더 목록</a>
-      <h1>📁 <%= folder %></h1>
+      <a class="muted" href="<%= parentHref %>"><%= parentLabel %></a>
+      <h1>📁 <%= breadcrumb.join(' / ') %></h1>
    </section>

+    <% if (subFolders && subFolders.length > 0) { %>
+      <section class="folderGrid">
+        <% subFolders.forEach(function (sf) { %>
+          <a class="folderCard" href="/folder/<%= folderPathEnc %>/<%= encodeURIComponent(sf.name) %>">
+            <span class="folderIcon">📁</span>
+            <span class="folderName"><%= sf.name %></span>
+          </a>
+        <% }) %>
+      </section>
+    <% } %>
+
    <section class="videoGrid">
-      <% if (videos.length === 0) { %>
+      <% if (videos.length === 0 && (!subFolders || subFolders.length === 0)) { %>
        <p class="muted">이 폴더에 영상이 없습니다.</p>
      <% } %>
      <% videos.forEach(function (v) { %>
-        <button type="button" class="videoCard" data-video-id="<%= v.id %>">
+        <%
+          var shareUrl = '/video/' + folderPathEnc + '/' + encodeURIComponent(v.id)
+        %>
+        <a class="videoCard" href="<%= shareUrl %>"
+           data-video-id="<%= v.id %>" data-share-url="<%= shareUrl %>">
          <div class="videoThumb">▶</div>
          <div class="videoTitle"><%= v.title %></div>
-        </button>
+        </a>
      <% }) %>
    </section>
  </main>

-  <div class="playerOverlay" id="playerOverlay" hidden>
-    <div class="playerModal" role="dialog" aria-modal="true">
-      <button type="button" class="playerClose" id="playerClose" aria-label="닫기">✕</button>
-      <div class="playerTitle" id="playerTitle"></div>
-      <video id="playerVideo" controls preload="metadata"></video>
-    </div>
-  </div>
-
  <div class="ctxMenu" id="ctxMenu" hidden>
    <button type="button" data-action="copyUrl">영상 주소 복사</button>
  </div>

-  <script>
-    window.__SITE__ = { folder: <%- jsonForScript(folder) %> }
-  </script>
-  <script src="/static/player.js"></script>
  <script src="/static/public-folder.js"></script>
 </body>
 </html>
--- a/views/index.ejs
+++ b/views/index.ejs
@@ -25,10 +25,10 @@
      <% if (folders.length === 0) { %>
        <p class="muted">아직 폴더가 없습니다. 관리자 페이지에서 폴더를 추가해 주세요.</p>
      <% } %>
-      <% folders.forEach(function (name) { %>
-        <a class="folderCard" href="/folder/<%= encodeURIComponent(name) %>">
+      <% folders.forEach(function (f) { %>
+        <a class="folderCard" href="/folder/<%= encodeURIComponent(f.name) %>">
          <span class="folderIcon">📁</span>
-          <span class="folderName"><%= name %></span>
+          <span class="folderName"><%= f.name %></span>
        </a>
      <% }) %>
    </section>
--- a/views/op/dashboard.ejs
+++ b/views/op/dashboard.ejs
@@ -21,11 +21,11 @@
      <% if (folders.length === 0) { %>
        <p class="muted">아직 폴더가 없습니다. 우측 상단에서 폴더를 추가해 주세요.</p>
      <% } %>
-      <% folders.forEach(function (name) { %>
-        <div class="folderCard adminFolder" data-name="<%= name %>">
-          <a class="folderCardLink" href="/op/folder/<%= encodeURIComponent(name) %>">
+      <% folders.forEach(function (f) { %>
+        <div class="folderCard adminFolder" data-folder-id="<%= f.id %>" data-name="<%= f.name %>">
+          <a class="folderCardLink" href="/op/folder/<%= encodeURIComponent(f.name) %>">
            <span class="folderIcon">📁</span>
-            <span class="folderName"><%= name %></span>
+            <span class="folderName"><%= f.name %></span>
          </a>
        </div>
      <% }) %>
--- a/views/op/editor.ejs
+++ b/views/op/editor.ejs
@@ -3,13 +3,18 @@
 <head>
  <meta charset="utf-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1" />
-  <title>영상 편집 · <%= folder %></title>
+  <title>영상 편집 · <%= breadcrumb.join(' / ') %></title>
  <link rel="stylesheet" href="/static/styles.css" />
 </head>
 <body class="siteBody">
+  <%
+    var folderPathEnc = breadcrumb.map(function (s) { return encodeURIComponent(s) }).join('/')
+    var folderHref = '/op/folder/' + folderPathEnc
+    var folderLabel = breadcrumb.join(' / ')
+  %>
  <header class="editorNav">
    <div class="editorNavLeft">
-      <a class="muted" href="/op/folder/<%= encodeURIComponent(folder) %>">← <%= folder %></a>
+      <a class="muted" href="<%= folderHref %>">← <%= folderLabel %></a>
      <input type="text" id="titleInput" class="titleInput" placeholder="영상 제목" value="<%= video ? video.title : '' %>" />
    </div>
    <div class="editorNavRight">
@@ -35,7 +40,7 @@

      <div id="videoPanel" class="videoPanel" <% if (!video) { %>hidden<% } %>>
        <video id="editVideo" controls preload="metadata"
-          <% if (video) { %>src="/api/video/<%= video.id %>/file?edited=0"<% } %>></video>
+          <% if (video) { %>src="/api/video/<%= encodeURIComponent(video.id) %>/file?edited=0"<% } %>></video>

        <div class="trimTimeline">
          <div class="trimTimelineHeader">
@@ -66,7 +71,8 @@

  <script>
    window.__EDITOR__ = {
-      folder: <%- jsonForScript(folder) %>,
+      folderPath: <%- jsonForScript(breadcrumb) %>,
+      folderId: <%- jsonForScript(folder.id) %>,
      video: <%- jsonForScript(video) %>
    }
  </script>
--- a/views/op/folder.ejs
+++ b/views/op/folder.ejs
@@ -3,32 +3,65 @@
 <head>
  <meta charset="utf-8" />
  <meta name="viewport" content="width=device-width, initial-scale=1" />
-  <title>관리자 · <%= folder %></title>
+  <title>관리자 · <%= breadcrumb.join(' / ') %></title>
  <link rel="stylesheet" href="/static/styles.css" />
 </head>
 <body class="siteBody">
  <%- include('../partials/navbar', { userId }) %>

+  <%
+    var folderPathEnc = breadcrumb.map(function (s) { return encodeURIComponent(s) }).join('/')
+    var parentHref = isSubFolder ? '/op/folder/' + encodeURIComponent(breadcrumb[0]) : '/op/dashboard'
+    var parentLabel = isSubFolder ? '← ' + breadcrumb[0] : '← 폴더 목록'
+    var editorHref = '/op/folder/' + folderPathEnc + '/video/editor'
+    var playlistHref = '/op/folder/' + folderPathEnc + '/playlist/new'
+  %>
+
  <main class="pageWrap">
    <section class="dashboardHeader">
      <div>
-        <a class="muted" href="/op/dashboard">← 폴더 목록</a>
-        <h1>📁 <%= folder %></h1>
+        <a class="muted" href="<%= parentHref %>"><%= parentLabel %></a>
+        <h1>📁 <%= breadcrumb.join(' / ') %></h1>
      </div>
      <div class="dashboardActions">
-        <a class="primaryButton" href="/op/folder/<%= encodeURIComponent(folder) %>/video/editor">영상 추가</a>
+        <% if (!isSubFolder) { %>
+          <button type="button" class="secondaryButton" id="addSubFolderBtn">하위 폴더 추가</button>
+        <% } %>
+        <a class="primaryButton" href="<%= editorHref %>">영상 추가</a>
+        <% if (isSubFolder) { %>
+          <a class="primaryButton" href="<%= playlistHref %>">플레이리스트 추가</a>
+        <% } %>
      </div>
    </section>

+    <% if (!isSubFolder && subFolders && subFolders.length > 0) { %>
+      <section class="folderGrid" id="subFolderGrid">
+        <% subFolders.forEach(function (sf) { %>
+          <div class="folderCard adminFolder" data-folder-id="<%= sf.id %>" data-name="<%= sf.name %>">
+            <a class="folderCardLink" href="/op/folder/<%= folderPathEnc %>/<%= encodeURIComponent(sf.name) %>">
+              <span class="folderIcon">📁</span>
+              <span class="folderName"><%= sf.name %></span>
+            </a>
+          </div>
+        <% }) %>
+      </section>
+    <% } %>
+
    <section class="videoGrid" id="videoGrid">
-      <% if (videos.length === 0) { %>
+      <% if (videos.length === 0 && (isSubFolder || !subFolders || subFolders.length === 0)) { %>
        <p class="muted">이 폴더에 영상이 없습니다. 우측 상단에서 영상을 추가하세요.</p>
      <% } %>
-      <% videos.forEach(function (v) { %>
-        <div class="videoCard adminVideo" data-id="<%= v.id %>" data-video-id="<%= v.id %>" data-title="<%= v.title %>">
+      <% videos.forEach(function (v) {
+           var shareUrl = '/video/' + folderPathEnc + '/' + encodeURIComponent(v.id)
+      %>
+        <div class="videoCard adminVideo"
+             data-id="<%= v.id %>"
+             data-video-id="<%= v.id %>"
+             data-title="<%= v.title %>"
+             data-share-url="<%= shareUrl %>">
          <div class="videoThumb">▶</div>
          <div class="videoTitle"><%= v.title %></div>
-          <% if (v.sourceType === 'youtube' && !v.originalFile.includes('original.') === false) { %>
+          <% if (v.sourceType === 'youtube') { %>
            <div class="muted">YouTube</div>
          <% } %>
        </div>
@@ -39,10 +72,16 @@
  <div class="ctxMenu" id="ctxMenu" hidden>
    <button type="button" data-action="edit">수정</button>
    <button type="button" data-action="rename">이름 변경</button>
+    <button type="button" data-action="changeId">ID 변경</button>
    <button type="button" data-action="copyUrl">영상 주소 복사</button>
    <button type="button" data-action="delete" class="dangerLink">삭제</button>
  </div>

+  <div class="ctxMenu" id="folderCtxMenu" hidden>
+    <button type="button" data-action="rename">이름 변경</button>
+    <button type="button" data-action="delete" class="dangerLink">삭제</button>
+  </div>
+
  <div class="playerOverlay" id="playerOverlay" hidden>
    <div class="playerModal" role="dialog" aria-modal="true">
      <button type="button" class="playerClose" id="playerClose" aria-label="닫기">✕</button>
@@ -51,9 +90,26 @@
    </div>
  </div>

+  <div class="modalOverlay" id="addSubFolderModal" hidden>
+    <div class="modalCard">
+      <h2>하위 폴더 추가</h2>
+      <label>
+        <span>폴더 이름</span>
+        <input type="text" id="addSubFolderInput" autofocus />
+      </label>
+      <div class="modalActions">
+        <button type="button" class="secondaryButton" id="addSubFolderCancel">취소</button>
+        <button type="button" class="primaryButton" id="addSubFolderConfirm">생성</button>
+      </div>
+    </div>
+  </div>
+
  <script>
-    window.__OP__ = { folder: <%- jsonForScript(folder) %> }
-    window.__SITE__ = { folder: <%- jsonForScript(folder) %> }
+    window.__OP__ = {
+      folderId: <%- jsonForScript(folder.id) %>,
+      folderPath: <%- jsonForScript(breadcrumb) %>,
+      isSubFolder: <%- jsonForScript(isSubFolder) %>
+    }
  </script>
  <script src="/static/folder.js"></script>
  <script src="/static/player.js"></script>
--- a/views/player.ejs
+++ b/views/player.ejs
@@ -7,22 +7,27 @@
  <link rel="stylesheet" href="/static/styles.css" />
 </head>
 <body class="siteBody">
+  <%
+    var folderPathEnc = breadcrumb.map(function (s) { return encodeURIComponent(s) }).join('/')
+    var folderHref = '/folder/' + folderPathEnc
+    var folderLabel = breadcrumb.join(' / ')
+  %>
  <header class="publicNav">
    <a class="navBrand" href="/">
      <span class="navLogo">🎬</span>
      <span class="navTitle">비디오 사이트</span>
    </a>
-    <a class="secondaryButton" href="/folder/<%= encodeURIComponent(folder) %>">폴더로</a>
+    <a class="secondaryButton" href="<%= folderHref %>">폴더로</a>
  </header>

  <main class="pageWrap">
    <section class="hero">
-      <a class="muted" href="/folder/<%= encodeURIComponent(folder) %>">← <%= folder %></a>
+      <a class="muted" href="<%= folderHref %>">← <%= folderLabel %></a>
      <h1><%= video.title %></h1>
    </section>

    <div class="standalonePlayer">
-      <video controls autoplay preload="metadata" src="/api/video/<%= video.id %>/file"></video>
+      <video controls autoplay preload="metadata" src="/api/video/<%= encodeURIComponent(video.id) %>/file"></video>
    </div>
  </main>
 </body>