A book is a folder of chapters, not a file. The scanner gained a grouping
mode so a directory of tracks becomes one item with ordered files.
- registry: MediaType.Group (file | directory). Audiobooks and music group by
directory; everything else stays one item per file.
- scanner: builds groups, upserts one item per group, marks items missing when
their directory disappears, and keeps the file-level added/updated/missing
accounting. Tracks are ordered naturally, so chapter 2 precedes chapter 10.
- natsort: one shared natural-order comparator, now used by both the scanner
and the comics module (which had its own copy).
- media: GET /items/{id}/files/{fileID} streams one specific track. It
verifies the file belongs to the item, so an item id cannot be paired with
another item's file id.
No new module was needed for playback: the polymorphic progress table already
keys on file_id, so per-chapter resume fell out of the existing design. The
web player resumes the exact track and offset.
Verified: 3 chapters grouped into one book titled "Mistborn", natural order,
range request returned 206, mismatched file id 404s, per-track progress
round-trips.
- library: CRUD with root-path resolution (absolute, symlink-free, must be
readable). A library name is unique; the root is validated at creation.
- registry: media types declare their extensions; the core never imports a
module. RegisterType is the extension point.
- scanner: walks a root, reconciles media_items/media_files in one
transaction, skips unchanged files by size+mtime, and marks vanished files
missing rather than deleting them (progress is the one thing here that
cannot be regenerated). A single unreadable file never fails a scan.
- migration 0002: `missing` flags on items and files, plus indexes.
- endpoints: media-types, library list/get/create/delete, per-library items,
and scan. Library reads go through the same grant chokepoint as everything
else; an unauthorised library 404s rather than 403s so its existence is not
leaked.