Return every playlist, folder and smartlist as a flat list of {id, name, path, kind, parent_id} rows in Lexicon's order, where path joins folder names with " / ". Pass tree=True for the raw nested tree. No track counts either way; use get_playlist_tracks for contents.

Return a playlist's tracks in playlist order. By default each record carries a compact field set (id, title, artist, albumTitle, genre, comment, bpm, key, energy, year, duration, rating, playCount, tags). Pass fields to choose exactly which fields, or full=True for the complete records including cue points and tempo markers (~3 KB each).

Search the library. filter maps field -> value/comparison, e.g. {"artist": "Daft Punk", "bpm": ">=120"}. Returns {total, returned, tracks}; results are capped by limit while total is the real count. Unsafe filters that would match the whole library are rejected.

Summarise the whole library in one call: track totals and how many carry bpm / key / energy / any tag; key notation in use (open_key, camelot, mixed); playlist counts by kind; every tag category and tag with the number of tracks carrying it. Scans all tracks (fast).

List tracks with no custom tags, as compact records. Give playlist_id to scope to one playlist (the natural unit of a tagging drive), or omit it to scan the whole library and page through the untagged subset with limit/offset; total_untagged is always the true count.

Return the full record for one track (metadata, tags, cues).

Return the custom-tag taxonomy: each category with its tags.

Create a custom-tag category (e.g. "Undertow") and return it with its new id. Labels must be unique; Lexicon rejects duplicates.

Create a custom tag inside a category and return it with its new id. Tag labels are unique across the whole library (case-sensitive).

Set a track's custom tags to EXACTLY tag_ids (replace). Entries may be tag ids or labels ("Genre/Afro House" or just "Afro House"). Pass [] to clear. To add without disturbing others, read the track and set the union, or use bulk_apply_tags for many tracks.

Add tag_ids (ids or labels like "Genre/Afro House") to each of track_ids (merge, never wipe). Refuses an empty set, a set over ceiling, or a mismatch with expected_count, before any write. Returns a summary of updated/unchanged/failed.

Create a smartlist from rules, e.g. [{"field": "bpm", "operator": "NumberGreaterThan", "values": [120]}]. match_all=True requires every rule (AND), False is ANY (OR).

Delete a smartlist and return {id, name, kind}. Folders are never deleted (the delete would cascade). An ordinary playlist is deleted only with allow_playlist=True; there is no undo.