.skim
|- subscriptions.opml                   # subscriptions and categories
|- feed-slug-a                          # a single feed
|  |- conditional-get                   # conditional GET state
|  |- feed.json                         # feed metadata
|  |- entries.db                        # entry slugs by URL, for deduplication
|  |- YYYY-MM-DDTHH:MM:SS-entry-slug-a  # a single entry
|  |  |- entry.json                     # entry metadata
|  |  |- body.md                        # markdown version
|  |  |- body.html                      # (cached) HTML version
|  |  |- image-a.png                    # locally cached image
|  |  |- ...
|  |- YYYY-MM-DDTHH:MM:SS-entry-slug-b
|  |- ...
|- feed-slug-b
|- ...
|- index
   |- search index files