Path format configuration matching on genres fails when using operands for exact matches

[twebr]

Problem

In my config.yaml, I put the following to use a different path format configuration for classical music:

paths:
    ## Special treatment for classical music
    genres:=~Classical: _Classical/$albumartist_sort/[$original_year]$atypes $album%aunique{albumartist album original_year}/$disc_and_track $title
    default: ...

At least up to beets v2.6.2, this worked fine.

But in my current version of beets (v2.10.0), songs that have genre 'Classical' do not match the path query on the left-hand side.
Interestingly, running $ beet list genres:=~Classical still works as expected.
It's just in the path format configuration that the query seems to fail finding any matches.

Removing the operands for an exact match (= or =~) results in classical music matching correctly in the path format configuration, but then I get false positives for genres that contain the substring 'classical'.
(For instance, I have music labelled as genre 'Neoclassical' which I do not want to match with this path format configuration.

I suspect that the bug was introduced when beets added support for multiple genres (deprecating the old genre field), but I am unable to verify this.

I already tried turning off plugins, but this did not resolve the issue.

Setup

• OS: macOS 15.7.5
• Python version: 3.13.12
• beets version: 2.10.0
• Turning off plugins made problem go away (yes/no): no

My configuration (output of beet config) is:

directory: REDACTED

import:
    copy: yes
    write: yes
    log: beetslog.txt
    timid: yes
    languages: en nl

# --------------- Plugins ---------------

plugins: export albumtypes info inline the lyrics embedart lastgenre badfiles smartplaylist filetote musicbrainz fetchart convert

# --------------- Tagging ---------------

per_disc_numbering: yes
format_album: $albumartist - $album ($original_year)

# --------------- Search ---------------

format_item: $artist - $album ($original_year) - $title
sort_item: artist+ original_year+ album+ disc+ track+

sort_album: albumartist+ original_year+ album+
original_date: yes
asciify_paths: yes

ui:
    colors:
        text_diff_added: [bold, green]
        text_diff_removed: [bold, red]
        text_diff_changed: [bold, yellow]
paths:
    genres:=~Classical: _Classical/$albumartist_sort/[$original_year]$atypes $album%aunique{albumartist album original_year}/$disc_and_track $title
    default: $albumartist_sort/[$original_year]$atypes $album%aunique{albumartist album original_year}/$disc_and_track $title
    singleton: _Singletons/$artist/$title
    comp: _Compilations/$year_reissue$atypes $album%aunique{albumartist album original_year}/$disc_and_track $artist - $title
item_fields:
    year_reissue: "f'[{original_year}\u2190{year}]' if original_year != year else f'[{original_year}]'"
    disc_and_track: f'{disc}-{track:02d}' if disctotal > 1 else f'{track:02d}'
the:
    strip: yes
    the: yes
    a: yes
    format: '{}, {}'
    patterns: []
export:
    csv:
        formatting:
            dialect: unix
            delimiter: ','
    default_format: json
    json:
        formatting:
            ensure_ascii: no
            indent: 4
            separators: &id001 [',', ': ']
            sort_keys: yes
    jsonlines:
        formatting:
            ensure_ascii: no
            separators: *id001
            sort_keys: yes
    xml:
        formatting: {}
albumtypes:
    types:
    -   ep: EP
    -   single: Single
    -   soundtrack: OST
    -   live: Live
    -   compilation: Comp
    -   remix: Remix
    ignore_va: compilation
    bracket: '[]'
fetchart:
    auto: no
    maxwidth: 500
    sources: [filesystem, coverart, itunes]
    minwidth: 0
    quality: 0
    max_filesize: 0
    enforce_ratio: no
    cautious: no
    cover_names:
    - cover
    - front
    - art
    - album
    - folder
    fallback:
    store_source: no
    high_resolution: no
    deinterlace: no
    cover_format:
    google_key: REDACTED
    google_engine: REDACTED
    lastfm_key: REDACTED
    fanarttv_key: REDACTED
embedart:
    auto: no
    maxwidth: 0
    compare_threshold: 0
    ifempty: no
    remove_art_file: no
    quality: 0
    clearart_on_import: no
filetote:
    extensions: .cue .log .png .jpg .pdf
    session:
        operation:
        _beets_lib:
        _library_path:
        import_path:
    filenames: ''
    patterns: {}
    exclude:
        filenames: ''
        extensions: ''
        patterns: {}
    pairing:
        enabled: no
        pairing_only: no
        extensions: .*
    paths: {}
    print_ignored: no
    duplicate_action: merge
edit:
    albumfields: album albumartist albumdisambig albumstatus genres language
lyrics:
    auto: no
    synced: yes
    auto_ignore:
    translate:
        api_key: REDACTED
        from_languages: []
        to_language:
    dist_thresh: 0.11
    google_API_key: REDACTED
    google_engine_ID: REDACTED
    genius_api_key: REDACTED
    fallback:
    force: no
    keep_synced: no
    local: no
    print: no
    sources: [lrclib, google, genius]
lastgenre:
    whitelist: genre_whitelist.txt
    canonical: yes
    force: yes
    keep_existing: no
    min_weight: 10
    count: 1
    fallback:
    cleanup_existing: no
    source: album
    auto: yes
    prefer_specific: no
    title_case: yes
    pretend: no
    ignorelist: {}
badfiles:
    check_on_import: yes
smartplaylist:
    playlist_dir: REDACTED
    relative_to: REDACTED
    playlists: [{name: More-than-CD quality.m3u8, query: 'bitdepth:17.. , samplerate:48000..'}, {name: Classical music.m3u8, query: 'genre:classical albumartist+ album+'}]
    dest_regen: no
    auto: yes
    uri_format:
    fields: []
    forward_slash: no
    prefix: REDACTED
    urlencode: no
    pretend_paths: no
    output: m3u
convert:
    dest: REDACTED
    command: ffmpeg -i $source -y -vn -acodec aac_at -aac_at_mode vbr -aac_at_quality 0 -q:a 7 $dest
    extension: m4a
    pretend: no
    link: no
    hardlink: no
    threads: 8
    format: mp3
    id3v23: inherit
    write_metadata: yes
    formats:
        aac:
            command: ffmpeg -i $source -y -vn -acodec aac -aq 1 $dest
            extension: m4a
        alac:
            command: ffmpeg -i $source -y -vn -acodec alac $dest
            extension: m4a
        flac: ffmpeg -i $source -y -vn -acodec flac $dest
        mp3: ffmpeg -i $source -y -vn -aq 2 $dest
        opus: ffmpeg -i $source -y -vn -acodec libopus -ab 96k $dest
        ogg: ffmpeg -i $source -y -vn -acodec libvorbis -aq 3 $dest
        wma: ffmpeg -i $source -y -vn -acodec wmav2 -vn $dest
    max_bitrate:
    auto: no
    auto_keep: no
    tmpdir:
    quiet: no
    embed: yes
    paths: {}
    no_convert: ''
    never_convert_lossy_files: no
    copy_album_art: no
    album_art_maxwidth: 0
    delete_originals: no
    playlist:
disabled_plugins: []
pathfields: {}
album_fields: {}
musicbrainz:
    search_limit: 5
    data_source_mismatch_penalty: 0.5
    search_query_ascii: no
    genres: no
    genres_tag: genre
    external_ids:
        discogs: no
        bandcamp: no
        spotify: no
        deezer: no
        tidal: no
    extra_tags: []