feat: support folder uploads in the asset library

[stevenle]

Adds support for uploading entire folder structures to the asset library, mirroring the directory hierarchy in the asset browser. Users can now upload folders in addition to individual files.

Changes

• File tree utilities (file-tree.ts): New module for collecting files from folder uploads via two mechanisms:

  • Directory picker (<input type="file" webkitdirectory>) where files carry webkitRelativePath
  • Drag-and-drop with recursive directory walking via the webkitGetAsEntry() file system API
  • Filters out OS metadata files (.DS_Store, Thumbs.db, etc.) and directories (__MACOSX, dotdirs)
  • Caps uploads at 1000 files to bound resource usage

• Asset folder creation (assets.ts): New createAssetFolderPaths() function that:

  • Creates missing folder hierarchies before file uploads
  • Validates folder path segments using existing validateAssetName()
  • Batches Firestore writes (max 400 ops per batch) to stay within limits
  • Caps folder creation at 200 folders per upload
  • Preserves existing folders and their metadata/sync connections

• Asset browser UI (AssetBrowser.tsx):

  • Refactored uploadFiles() to accept UploadFileEntry[] instead of raw File[]
  • In "manage" mode, upload button now shows a dropdown menu with "Upload files" and "Upload folder" options
  • Drag-and-drop now supports folders (updated hint text)
  • Handles folder creation errors gracefully with user notification
  • Shows truncation warning if upload exceeds 1000 files

• Tests (file-tree.test.ts): Comprehensive test coverage for file collection, ignored file/directory filtering, and both upload mechanisms.

Implementation Details

• UploadFileEntry carries both the file and its relative path within the upload, allowing the asset browser to recreate the folder structure
• Folder paths are validated and normalized before creation to ensure consistency
• The drag-and-drop implementation reads entries synchronously (before any await) since DataTransfer is only valid during the event
• Existing folders are checked before creation to avoid unnecessary writes and preserve user-created metadata

https://claude.ai/code/session_01LRRKBNbBnYV1uhgXo28T8u