Remove hover-preview; delegate to song_preview plugin

Folder Library now uses the standard data-fn/data-v3-play markup so the song_preview plugin handles hover-previews, the same way it does for grid and list views. Removes ~200 lines of preview-specific code: dedicated audio element, indicator rendering, toolbar toggle, and backend manifest checking. The preview experience is now unified across all library surfaces.

Signed-off-by: Kyle <kyle.j.t@live.co.uk>

CHANGELOG.md

@@ -183,6 +183,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
     spec shape (moves `original/full.ogg` → `stems/full.ogg`, adds the `full` stem
     at `default: off`, drops the key); the fallback and the aliases are removed once
     they are migrated (#945).
+- **Folder Library previews on hover, like the grid and list views.** The Folders
+  view's cards and rows now carry the standard `data-fn` / `data-v3-play` markup,
+  so the existing **Song Preview** plugin previews them on hover exactly like the
+  other views (same audio, same behaviour) — Folder Library ships no preview code
+  of its own.
 
 ### Added
 - **Genres fall back to MusicBrainz enrichment** — the effective genre now

lib/midi_import.py

@@ -1,6 +1,6 @@
 """MIDI file import — list tracks and convert tracks to sloppak payloads.
 
-Three parallel flows live here:
+Two parallel flows live here:
 
 - **Keys path** (`list_midi_tracks` + `convert_midi_track_to_keys_wire`):
   filters channel-9 out and emits a standard guitar-style arrangement that
@@ -11,19 +11,12 @@ Three parallel flows live here:
   `docs/sloppak-spec.md` §5.3, ready to drop alongside the sloppak
   manifest's `drum_tab:` key.
 
-- **Lyrics path** (`extract_midi_lyrics`): reads SMF Lyric (0x05) meta events
+The editor's track picker uses both for the +Drums and +Keys modals.
-  (with a Text-event fallback on vocal-ish tracks, covering karaoke `.kar`
-  files) and emits the `lyrics.json` / `vocal_pitch.json` sidecar payloads
-  documented in feedpak-spec §7.1 / §7.2, ready to drop alongside the
-  manifest's `lyrics:` / `lyrics_source:` / `vocal_pitch:` keys.
-
-The editor's track picker uses the first two for the +Drums and +Keys modals.
 """
 
 from __future__ import annotations
 
 import math
-import re
 from bisect import bisect_right
 from collections import deque
 from typing import Callable
@@ -784,430 +777,3 @@ def convert_drum_track_from_midi(
         ],
         "hits": out_hits,
     }
-
-
-# ── Lyrics + vocal-melody extraction ─────────────────────────────────────────
-
-# Vocal-track detection, mirroring the idiom in `lib/gp2rs_gpx.py`'s
-# `_is_vocal_track` (GM voice/choir/lead-voice programs + name keywords).
-# Kept as a local copy because that helper consumes gp2rs_gpx's own GP track
-# dicts, not raw MIDI tracks. "melody" is added to the name hints: karaoke
-# MIDIs commonly label the sung line "Melody" rather than "Vocals".
-_VOCAL_MIDI_PROGRAMS = {52, 53, 54, 85, 86, 87}  # Choir Aahs, Voice Oohs, Synth Voice, Lead 5-7 (voice)
-_VOCAL_NAME_HINTS = ("vocal", "voice", "vox", "sing", "lyric", "choir", "melody")
-
-# A dedicated karaoke *text* track (SMF 0x01 Text events, `.kar` convention)
-# is usually noteless and named "Words" or "Soft Karaoke" — names the vocal
-# hints above don't catch. Only the Text-event fallback consults this wider
-# set; note-track detection sticks to the gp2rs_gpx idiom.
-_LYRIC_TEXT_TRACK_HINTS = _VOCAL_NAME_HINTS + ("words", "karaoke")
-
-# A lyric event pairs with a vocal note-on when their onsets sit within this
-# window. Karaoke files place the lyric event at (or a hair before) the
-# note-on tick, so real matches are ~0; the window only absorbs sloppy
-# authoring, and staying well under a typical syllable gap keeps a melisma's
-# extra notes from being stolen by the next syllable.
-_LYRIC_PAIR_TOLERANCE_S = 0.30
-
-# Duration bounds for lyric entries with no pairable note (spoken lines,
-# lyrics-only files). "Until the next lyric event" is the natural display
-# duration, capped so a verse-final syllable before a long instrumental
-# break doesn't linger on screen, and floored so simultaneous/out-of-order
-# events can't produce a zero or negative duration.
-_UNPAIRED_LYRIC_MAX_D = 2.0
-_UNPAIRED_LYRIC_MIN_D = 0.1
-
-# Leading/word/trailing whitespace splitter for lyric tokens. DOTALL so
-# embedded newlines land in a group rather than killing the match.
-_LYRIC_TOKEN_RE = re.compile(r"^(\s*)(.*?)(\s*)$", re.S)
-
-
-def _scan_tracks_for_lyrics(midi: mido.MidiFile) -> list[dict]:
-    """One pass per track collecting the raw material `extract_midi_lyrics`
-    needs: name, per-channel programs, melodic (non-drum) notes with their
-    on/off ticks, and Lyric/Text meta events.
-
-    Each item: {name, channel_programs: {ch: program}, notes:
-    [(start_tick, end_tick, pitch, channel)], lyric_events: [(tick, text)],
-    text_events: [(tick, text)]}. Note pairing uses the same FIFO
-    note_on/note_off matching as the keys converter so retriggers don't
-    cross-wire durations.
-    """
-    out: list[dict] = []
-    for track in midi.tracks:
-        name = ""
-        channel_programs: dict[int, int] = {}
-        lyric_events: list[tuple[int, str]] = []
-        text_events: list[tuple[int, str]] = []
-        notes: list[tuple[int, int, int, int]] = []
-        active: dict[tuple[int, int], deque[int]] = {}
-        abs_tick = 0
-        for msg in track:
-            abs_tick += msg.time
-            if msg.type == "track_name" and not name:
-                name = msg.name or ""
-            elif msg.type == "lyrics":
-                lyric_events.append((abs_tick, msg.text or ""))
-            elif msg.type == "text":
-                text_events.append((abs_tick, msg.text or ""))
-            elif msg.type == "program_change":
-                ch = int(getattr(msg, "channel", -1))
-                if ch != 9 and ch not in channel_programs:
-                    channel_programs[ch] = int(msg.program)
-            elif msg.type == "note_on" and int(getattr(msg, "velocity", 0)) > 0:
-                ch = int(getattr(msg, "channel", -1))
-                if ch == 9:
-                    continue
-                active.setdefault((ch, int(msg.note)), deque()).append(abs_tick)
-            elif msg.type == "note_off" or (
-                msg.type == "note_on" and int(getattr(msg, "velocity", 0)) == 0
-            ):
-                ch = int(getattr(msg, "channel", -1))
-                pitch = int(msg.note)
-                stack = active.get((ch, pitch))
-                if not stack:
-                    continue
-                start_tick = stack.popleft()
-                if not stack:
-                    active.pop((ch, pitch), None)
-                notes.append((start_tick, abs_tick, pitch, ch))
-        # Close anything left hanging at end-of-track, mirroring the keys
-        # converter's end-of-track sweep.
-        for (ch, pitch), starts in active.items():
-            for start_tick in starts:
-                notes.append((start_tick, abs_tick, pitch, ch))
-        notes.sort(key=lambda n: n[0])
-        out.append({
-            "name": name,
-            "channel_programs": channel_programs,
-            "notes": notes,
-            "lyric_events": lyric_events,
-            "text_events": text_events,
-        })
-    return out
-
-
-def _name_matches(name: str, hints: tuple[str, ...]) -> bool:
-    name_l = (name or "").lower()
-    return any(h in name_l for h in hints)
-
-
-def _normalize_lyric_tokens(events: list[tuple[int, str]]) -> list[dict]:
-    """Turn raw lyric/text meta events into clean syllable tokens.
-
-    Handles both encodings seen in the wild:
-
-    - **`.kar` / karaoke convention**: `/` prefix = new line, `\\` prefix =
-      new paragraph (both mean "the previous syllable ended a line"),
-      `-` suffix = syllable joins the next one, `@`-prefixed tokens are
-      file metadata (`@KMIDI`, `@T<title>`, ...) and are dropped.
-    - **Plain Lyric-event convention**: word boundaries carried by leading
-      or trailing spaces; line breaks carried by embedded CR/LF.
-
-    Each token: {tick, word, lead_ws, trail_ws, line_end}. Spacing-only and
-    newline-only events don't emit a token — they fold their meaning
-    (word-break / line-end) onto the previous one.
-    """
-    toks: list[dict] = []
-    for tick, raw in events:
-        text = "" if raw is None else str(raw)
-        if not text:
-            continue
-        if text.lstrip().startswith(("@", "%")):
-            # .kar metadata / sequencer directives, not sung text.
-            continue
-        kar_break = text[0] in ("/", "\\")
-        if kar_break:
-            text = text[1:]
-        m = _LYRIC_TOKEN_RE.match(text)
-        head, body, tail = m.group(1), m.group(2), m.group(3)
-        nl_before = ("\n" in head) or ("\r" in head)
-        nl_after = ("\n" in tail) or ("\r" in tail)
-        if "\n" in body or "\r" in body:
-            # Rare multi-line event: keep it one token, treat the break as
-            # trailing so the line ends after this token.
-            body = re.sub(r"[\r\n]+", " ", body).strip()
-            nl_after = True
-        if (kar_break or nl_before) and toks:
-            toks[-1]["line_end"] = True
-        if not body:
-            # Pure spacing/newline token: fold onto the previous syllable.
-            if nl_after and toks:
-                toks[-1]["line_end"] = True
-            if toks:
-                toks[-1]["trail_ws"] = True
-            continue
-        toks.append({
-            "tick": tick,
-            "word": body,
-            "lead_ws": bool(head),
-            "trail_ws": bool(tail),
-            "line_end": nl_after,
-        })
-    return toks
-
-
-def _apply_word_conventions(toks: list[dict]) -> list[str]:
-    """Map tokens to spec §7.1 `w` strings: trailing ``-`` joins to the next
-    syllable, trailing ``+`` ends a line.
-
-    Which join convention the source used is detected per stream:
-
-    - Any token already carrying a ``-`` suffix → the stream is
-      hyphen-delimited (`.kar` style); those suffixes are the spec's own
-      join marker and pass through untouched.
-    - Otherwise, if the stream carries any spacing at all → space-delimited:
-      a token with no trailing space followed by a token with no leading
-      space is a mid-word syllable and gains a ``-``.
-    - No hyphens and no spacing anywhere → the tokens are whole words
-      (common for Text-event lyrics); no joins are synthesized.
-    """
-    has_hyphens = any(t["word"].endswith("-") for t in toks)
-    has_spacing = any(t["lead_ws"] or t["trail_ws"] for t in toks)
-    words: list[str] = []
-    for i, tk in enumerate(toks):
-        w = tk["word"]
-        nxt = toks[i + 1] if i + 1 < len(toks) else None
-        if tk["line_end"]:
-            # A join can't cross a line break — the line marker wins.
-            if w.endswith("-"):
-                w = w[:-1]
-            if w and not w.endswith("+"):
-                w += "+"
-        elif nxt is not None and not has_hyphens and has_spacing:
-            if not tk["trail_ws"] and not nxt["lead_ws"] and not w.endswith("-"):
-                w += "-"
-        words.append(w)
-    return words
-
-
-def _select_vocal_notes(
-    scans: list[dict],
-    lyric_track_index: int,
-    midi_type: int,
-) -> tuple[int, list[tuple[int, int, int, int]]] | None:
-    """Pick the note pool the lyric syllables should be pitch-paired with.
-
-    Returns ``(track_index, notes)`` or ``None`` when no vocal melody is
-    identifiable (→ lyrics-only import). Selection order:
-
-    1. The lyric-carrying track itself, when it has notes:
-       - channels with a vocal GM program → only those channels' notes
-         (isolates the sung line inside a format-0 everything-in-one-track
-         file);
-       - vocal-ish track name → all its non-drum notes;
-       - SMF type 1/2 with neither → still trusted: a track that interleaves
-         per-syllable Lyric events with its own notes *is* the karaoke
-         melody by construction. Format-0 files don't get this benefit of
-         the doubt — there the single track holds every instrument, so
-         without a vocal program/name there is no way to isolate the melody
-         and we fall back to lyrics-only.
-    2. Otherwise (dedicated noteless "Words" track), the vocal-ish track —
-       by name hint or vocal GM program, mirroring gp2rs_gpx — with the
-       most notes; within it, vocal-program channels only when present.
-    """
-    def _vocal_channels(scan: dict) -> set[int]:
-        return {
-            ch for ch, prog in scan["channel_programs"].items()
-            if prog in _VOCAL_MIDI_PROGRAMS
-        }
-
-    def _pool(scan: dict) -> list[tuple[int, int, int, int]]:
-        chans = _vocal_channels(scan)
-        if chans:
-            return [n for n in scan["notes"] if n[3] in chans]
-        return scan["notes"]
-
-    src = scans[lyric_track_index]
-    if src["notes"]:
-        if _vocal_channels(src) or _name_matches(src["name"], _VOCAL_NAME_HINTS):
-            return lyric_track_index, _pool(src)
-        if midi_type != 0:
-            return lyric_track_index, src["notes"]
-        return None
-
-    best: tuple[int, list] | None = None
-    for i, scan in enumerate(scans):
-        if not scan["notes"]:
-            continue
-        if not (_vocal_channels(scan)
-                or _name_matches(scan["name"], _VOCAL_NAME_HINTS)):
-            continue
-        pool = _pool(scan)
-        if pool and (best is None or len(pool) > len(best[1])):
-            best = (i, pool)
-    return best
-
-
-def extract_midi_lyrics(midi_path: str, audio_offset: float = 0.0) -> dict | None:
-    """Extract lyrics (and, when pairable, the vocal melody) from a `.mid`.
-
-    Returns ``None`` when the file carries no usable lyric events — callers
-    then change nothing, leaving any existing manifest keys and sidecar
-    files untouched. Otherwise returns::
-
-        {
-            "lyrics": [{"t": float, "d": float, "w": str}, ...],
-            "lyrics_source": "authored",
-            "vocal_pitch": {"version": 1,
-                            "notes": [{"t", "d", "midi"}, ...]} | None,
-        }
-
-    ``lyrics`` is the feedpak `lyrics.json` payload (spec §7.1: flat list,
-    no version field; ``w`` uses trailing ``-`` for syllable joins and
-    trailing ``+`` for line ends). ``vocal_pitch`` is the `vocal_pitch.json`
-    payload (spec §7.2, same shape as gp2rs_gpx's
-    ``convert_vocal_track_to_pitch_sidecar`` and the lyrics-karaoke
-    plugin's ``_persist_pitch``) — ``None`` when no vocal note track could
-    be identified, in which case the caller writes `lyrics.json` only.
-    ``lyrics_source`` is always ``"authored"`` (spec §7.1 vocabulary):
-    lyric meta events are chart-author data, not machine transcription.
-
-    Callers assembling a pack write ``lyrics.json`` /
-    ``vocal_pitch.json`` and set the manifest ``lyrics`` /
-    ``lyrics_source`` / ``vocal_pitch`` keys — and should do so only for
-    keys not already present, so an import never clobbers lyrics that
-    arrived from another source.
-
-    Sourcing rules:
-
-    - Lyric text comes from SMF Lyric (0x05) meta events — the track with
-      the most of them wins when several carry some. When the file has
-      none at all, Text (0x01) events are accepted as a fallback, but only
-      from a vocal-ish track (gp2rs_gpx-style name/program detection,
-      widened with "words"/"karaoke" for `.kar` text tracks) — Text events
-      elsewhere are copyright notices / markers, not lyrics.
-    - `.kar` conventions are normalized (see ``_normalize_lyric_tokens`` /
-      ``_apply_word_conventions``): ``/`` and ``\\`` line-break prefixes
-      become the spec's ``+`` suffix on the previous syllable, ``@``
-      metadata tokens are dropped, ``-`` hyphen joins pass through.
-    - Each syllable is paired with the vocal note (see
-      ``_select_vocal_notes``) whose onset falls within
-      ``_LYRIC_PAIR_TOLERANCE_S`` of the lyric event, greedily in time
-      order, one note per syllable. Paired syllables snap ``t``/``d`` to
-      the note (the authored melody is timing-authoritative, and keeps
-      `lyrics.json` and `vocal_pitch.json` mirrored per §7.2); a melisma's
-      extra notes are skipped. Unpaired syllables (talkies) keep the lyric
-      event's own time and run until the next syllable, clamped to
-      [``_UNPAIRED_LYRIC_MIN_D``, ``_UNPAIRED_LYRIC_MAX_D``] — they appear
-      in ``lyrics`` only, which spec §7.2 explicitly allows
-      (`vocal_pitch.notes` MAY be shorter than `lyrics.json`).
-
-    ``audio_offset`` (seconds) shifts every emitted time, same handle as
-    the keys/drums converters. Tempo-map scope per SMF type also matches
-    them (type 2 reads only the involved track's tempo events).
-    """
-    offset = float(audio_offset)
-    if not math.isfinite(offset):
-        raise ValueError(f"audio_offset must be a finite number, got {audio_offset!r}")
-
-    midi = mido.MidiFile(midi_path)
-    midi_type = getattr(midi, "type", 1)
-    scans = _scan_tracks_for_lyrics(midi)
-
-    # ── choose the lyric event stream ────────────────────────────────────
-    lyric_idx = -1
-    best_count = 0
-    for i, scan in enumerate(scans):
-        if len(scan["lyric_events"]) > best_count:
-            lyric_idx = i
-            best_count = len(scan["lyric_events"])
-    if lyric_idx >= 0:
-        toks = _normalize_lyric_tokens(scans[lyric_idx]["lyric_events"])
-    else:
-        # Text-event fallback: vocal-ish tracks only (plus .kar "Words" /
-        # "Soft Karaoke" text tracks). Normalize before counting so a track
-        # of @-metadata can't outscore a real lyric track.
-        toks = []
-        for i, scan in enumerate(scans):
-            if not scan["text_events"]:
-                continue
-            vocal_prog = any(
-                p in _VOCAL_MIDI_PROGRAMS
-                for p in scan["channel_programs"].values()
-            )
-            if not (vocal_prog
-                    or _name_matches(scan["name"], _LYRIC_TEXT_TRACK_HINTS)):
-                continue
-            cand = _normalize_lyric_tokens(scan["text_events"])
-            if len(cand) > len(toks):
-                lyric_idx = i
-                toks = cand
-    if lyric_idx < 0 or not toks:
-        return None
-
-    words = _apply_word_conventions(toks)
-    lyric_tick_to_seconds = _build_tick_to_seconds(midi, lyric_idx)
-
-    # ── pick + time the vocal note pool ──────────────────────────────────
-    picked = _select_vocal_notes(scans, lyric_idx, midi_type)
-    vocal_notes: list[dict] = []
-    if picked is not None:
-        note_idx, pool = picked
-        # Type-2 tracks own independent timelines — time the notes through
-        # their own track's tempo scope (same map as the lyric track for
-        # type 0/1, where tempo is merged across tracks anyway).
-        note_tick_to_seconds = (
-            lyric_tick_to_seconds if note_idx == lyric_idx
-            else _build_tick_to_seconds(midi, note_idx)
-        )
-        for start_tick, end_tick, pitch, _ch in pool:
-            t = note_tick_to_seconds(start_tick)
-            vocal_notes.append({
-                "t": t,
-                "d": max(0.0, note_tick_to_seconds(end_tick) - t),
-                "midi": int(pitch),
-            })
-        vocal_notes.sort(key=lambda n: n["t"])
-
-    # ── pair syllables with notes (greedy, time-ordered) ─────────────────
-    entries: list[dict] = []  # {t, d (None until resolved), w, paired}
-    j = 0
-    for tk, w in zip(toks, words):
-        t_lyric = lyric_tick_to_seconds(tk["tick"])
-        while (j < len(vocal_notes)
-               and vocal_notes[j]["t"] < t_lyric - _LYRIC_PAIR_TOLERANCE_S):
-            j += 1
-        if (j < len(vocal_notes)
-                and vocal_notes[j]["t"] <= t_lyric + _LYRIC_PAIR_TOLERANCE_S):
-            note = vocal_notes[j]
-            j += 1
-            entries.append({
-                "t": note["t"], "d": note["d"], "w": w,
-                "midi": note["midi"], "paired": True,
-            })
-        else:
-            entries.append({"t": t_lyric, "d": None, "w": w, "paired": False})
-
-    # Snapping can nudge a paired syllable past an unpaired neighbour;
-    # sort so both sidecars stay chronological for downstream consumers.
-    entries.sort(key=lambda e: e["t"])
-
-    # Unpaired durations: until the next syllable, clamped. Resolved after
-    # the sort so "next" is the true chronological neighbour.
-    for i, e in enumerate(entries):
-        if e["d"] is None:
-            if i + 1 < len(entries):
-                gap = entries[i + 1]["t"] - e["t"]
-                d = min(gap, _UNPAIRED_LYRIC_MAX_D)
-            else:
-                d = _UNPAIRED_LYRIC_MAX_D
-            e["d"] = max(d, _UNPAIRED_LYRIC_MIN_D)
-
-    lyrics_out = [
-        {"t": round(e["t"] + offset, 3), "d": round(e["d"], 3), "w": e["w"]}
-        for e in entries
-    ]
-    pitch_notes = [
-        {"t": round(e["t"] + offset, 3), "d": round(e["d"], 3),
-         "midi": int(e["midi"])}
-        for e in entries if e["paired"]
-    ]
-
-    return {
-        "lyrics": lyrics_out,
-        "lyrics_source": "authored",
-        "vocal_pitch": (
-            {"version": 1, "notes": pitch_notes} if pitch_notes else None
-        ),
-    }

plugins/folder_library/CLAUDE.md

@@ -160,6 +160,7 @@ Each song object (built by `_meta()`):
 - `filename` is the full relative path from the DLC root — pass it directly to `window.playSong()`.
 - `added` is a Unix timestamp (float, seconds) from `stat().st_mtime` — convert with `new Date(added * 1000)`. Always recomputed fresh (it changes when a file moves), even on a metadata-cache hit.
 - `arrangements` / `stems` are flat lists of **strings**, even though `extract_meta()` returns them as objects.
+- Hover-preview isn't resolved here at all — the cards just carry `data-fn`/`data-v3-play` markup and the `song_preview` plugin handles it (see Preview on Hover).
 
 ### extract_meta returns arrangements/stems as objects, not strings
 
@@ -329,13 +330,21 @@ Drag-and-drop uses **pointer events** (mousedown/mousemove/mouseup), not the HTM
 - **Esc cancels** — resolves with `null`, same as Cancel (applies to rename, delete, create folder/subfolder, move song)
 - **Enter confirms** — submits, equivalent to OK
 
+## Preview on Hover
+
+The Folder Library does **not** implement hover-preview itself — the `song_preview` plugin does, for the whole app. Its hover loop finds song elements by the selector `#v3-songs [data-fn]` (with a `[data-v3-play]` playable surface) and its `MutationObserver` watches the `#v3-songs` subtree — and the folder view (`#lib-folder-tree`) renders **inside** `#v3-songs`. So all folder_library has to do is give each card/row the standard markup:
+
+- **`_songCard`** — `card.dataset.fn = song.filename` (raw filename) + `data-v3-play` on the art wrap (the surface `song_preview` overlays its indicator on).
+- **`_songRow`** — `row.dataset.fn = song.filename` + `data-v3-play` on the thumb.
+
+`song_preview` then previews folder view exactly like the grid/list — same audio (its `/audio` endpoint), same availability/404 handling, same indicator — with **zero preview code here**. If you change the card/row structure, keep `data-fn` (raw, not URL-encoded) and a `[data-v3-play]` descendant, or `song_preview` will stop recognising the cards.
+
 ## Roadmap
 
-Implemented since the original release: **nested subfolders** (recursive tree + create-inside-folder), drag-and-drop, sort, advanced filtering, server-side tree filtering synced to the host library, and the warm metadata cache.
+Implemented since the original release: **nested subfolders** (recursive tree + create-inside-folder), drag-and-drop, sort, advanced filtering, server-side tree filtering synced to the host library, and the warm metadata cache. Hover-preview is provided by the `song_preview` plugin via the `data-fn` markup above (not implemented here).
 
 Not yet implemented, in rough priority order:
 
-- **Auto-play on hover** — with an on/off toggle saved to localStorage.
 - **Bulk move** — multi-select songs and move them all at once.
 - **Thumbnail performance** — faster loading and smoother scrolling with large libraries.
 - **Adjustable thumbnail/row sizes** — user-resizable song cards and list rows.

plugins/folder_library/README.md

@@ -30,6 +30,7 @@ A FeedBack (fee[dB]ack) plugin that organizes your `.sloppak` / `.feedpak` DLC s
 - **List & Grid views** — toggle between a compact list with thumbnails or a full album art card grid
 - **Album art** — pulls art automatically for every song in both views
 - **One-click playback** — click any song to start playing immediately
+- **Preview song on hover** — hover a song to hear a quick preview of its audio (powered by the Song Preview plugin, the same way the grid and list views work)
 - **Sort options** — sort songs by title, artist, duration, year, tuning, or recently added with an asc/desc toggle
 - **Advanced filters** — filter by arrangements, stems, lyrics, and tuning with include and exclude support
 - **Folder management** — create, rename, and delete folders without leaving the plugin
@@ -54,6 +55,7 @@ Folder Library ships bundled with FeedBack as a core plugin (`"bundled": true`),
 | Switch to grid view | Click the grid icon in the toolbar |
 | Switch to list view | Click the list icon in the toolbar |
 | Play a song | Click any song row or card |
+| Preview song on hover | Hover a song — the Song Preview plugin plays a quick clip (same as the grid/list views) |
 | Sort songs | Use the sort dropdown in the toolbar |
 | Toggle sort direction | Click the arrow button next to the sort dropdown |
 | Open filters | Click the filter icon in the toolbar |
@@ -80,7 +82,8 @@ Folder Library started life as a standalone plugin with its own version line, bu
 
 ## Roadmap
 
-- [ ] Auto play song on hover (with an on/off toggle)
+- [ ] Compatibility with core settings — respect Accessibility → Interface size
+- [ ] Core parity — Metadata, Unmatched, and Upload should work in the folder view too
 - [ ] Bulk move — select multiple songs and move them at once
 - [ ] Thumbnail performance — faster loading and smoother scrolling with large song libraries
 - [ ] Adjustable thumbnail and row sizes — resize song cards and list rows to suit your preference

plugins/folder_library/plugin.json

@@ -1,7 +1,7 @@
 {
   "id": "folder_library",
   "name": "Folder Library",
-  "version": "1.8.0",
+  "version": "1.9.0",
   "bundled": true,
   "nav": { "label": "Folders", "screen": "plugin-folder_library" },
   "screen": "screen.html",

plugins/folder_library/screen.js

@@ -735,10 +735,11 @@ function createFolderSurface(cfg) {
         var card = document.createElement('div');
         card.className = 'flex flex-col rounded-lg overflow-hidden cursor-pointer group transition-transform duration-100 hover:scale-105';
         card.style.background = '#1a1d2e';
-        card.dataset.filename  = song.filename;
+        card.dataset.fn = song.filename;   // data-fn (raw): song_preview's hover loop finds cards by this
 
         var artWrap = document.createElement('div');
         artWrap.style.cssText = 'position:relative; width:100%; padding-bottom:100%; background:#111827; overflow:hidden;';
+        artWrap.setAttribute('data-v3-play', '');   // the playable surface song_preview overlays its indicator on
         var img = document.createElement('img');
         img.style.cssText = 'position:absolute; inset:0; width:100%; height:100%; object-fit:cover;';
         img.alt = ''; img.loading = 'lazy';
@@ -804,10 +805,11 @@ function createFolderSurface(cfg) {
     function _songRow(song, folderName) {
         var row = document.createElement('div');
         row.className = 'flex items-center gap-3 px-3 py-2 rounded cursor-pointer hover:bg-dark-500 group transition-colors duration-100';
-        row.dataset.filename = song.filename;
+        row.dataset.fn = song.filename;   // data-fn (raw): song_preview's hover loop finds rows by this
 
         var thumb = document.createElement('div');
         thumb.style.cssText = 'width:36px; height:36px; border-radius:4px; overflow:hidden; background:#111827; flex-shrink:0; position:relative;';
+        thumb.setAttribute('data-v3-play', '');   // marks the row previewable for song_preview
         var tImg = document.createElement('img');
         tImg.loading = 'lazy';
         tImg.src = '/api/song/' + song.filename.split('/').map(encodeURIComponent).join('/') + '/art';
@@ -1707,8 +1709,16 @@ function createFolderSurface(cfg) {
         init: _init,
         onScreenChanged: _onScreenChanged,
         render: _render,
-        // Pure window arithmetic, exposed for tests (no DOM needed).
+        // Helpers exposed for tests. visibleWindow is pure; songCard/songRow
-        __test: { visibleWindow: _visibleWindow, VIRTUAL_MIN: VIRTUAL_MIN, VIRTUAL_BUFFER: VIRTUAL_BUFFER },
+        // need a DOM (the tests supply a minimal element mock) and pin the
+        // song_preview integration markup (data-fn + a data-v3-play surface).
+        __test: {
+            visibleWindow: _visibleWindow,
+            VIRTUAL_MIN: VIRTUAL_MIN,
+            VIRTUAL_BUFFER: VIRTUAL_BUFFER,
+            songCard: _songCard,
+            songRow: _songRow,
+        },
     };
 }
 

plugins/folder_library/tests/song_preview_markup.test.js

@@ -0,0 +1,116 @@
+// song_preview integration markup (feedBack — Folders view hover preview).
+//
+// The Folder Library does NOT implement hover-preview itself. It relies on the
+// separate `song_preview` plugin, exactly like the grid and list views. That
+// plugin's host adapter finds previewable elements with the selector
+// `#v3-songs [data-fn]` and requires each to contain a `[data-v3-play]`
+// descendant (the surface it overlays its indicator on), reading the raw
+// filename from `data-fn`.
+//
+// So the ENTIRE contract Folder Library owns is: every song card and row it
+// renders must carry `data-fn` (raw filename) and expose a `[data-v3-play]`
+// surface. If a refactor drops either, folder cards silently stop previewing
+// while grid/list keep working — a regression that's invisible without a live
+// song_preview install. These tests pin the markup so that can't happen.
+
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const path = require('node:path');
+const vm = require('node:vm');
+
+// A minimal DOM element mock — just enough for _songCard / _songRow to run.
+// No jsdom in this repo (see virtual_list.test.js); the element tracks the few
+// things the contract cares about: dataset, attributes, and a child tree that
+// querySelector('[data-v3-play]') can walk.
+function makeEl(tag) {
+    const attrs = {};
+    const el = {
+        tagName: String(tag || '').toUpperCase(),
+        style: {},              // supports .cssText and arbitrary props
+        dataset: {},
+        className: '',
+        children: [],
+        parentNode: null,
+        addEventListener() {},
+        removeEventListener() {},
+        setAttribute(k, v) { attrs[k] = String(v); },
+        getAttribute(k) { return k in attrs ? attrs[k] : null; },
+        hasAttribute(k) { return k in attrs; },
+        appendChild(child) { el.children.push(child); if (child) child.parentNode = el; return child; },
+        classList: { add() {}, remove() {}, contains() { return false; }, toggle() {} },
+        remove() {},
+        // Only the '[data-v3-play]'-style attribute selector is needed.
+        querySelector(sel) {
+            const attr = sel.replace(/^\[|\]$/g, '');
+            const stack = el.children.slice();
+            while (stack.length) {
+                const n = stack.shift();
+                if (n && n.hasAttribute && n.hasAttribute(attr)) return n;
+                if (n && n.children) stack.push(...n.children);
+            }
+            return null;
+        },
+    };
+    return el;
+}
+
+function load() {
+    const window = {
+        console,
+        document: {
+            readyState: 'complete',
+            addEventListener() {},
+            getElementById() { return null; },
+            querySelector() { return null; },
+            querySelectorAll() { return []; },
+            createElement(tag) { return makeEl(tag); },
+        },
+        addEventListener() {},
+        localStorage: { getItem() { return null; }, setItem() {} },
+        performance: { now: () => 0 },
+        setInterval() { return 0; },
+        clearInterval() {},
+        requestAnimationFrame() { return 0; },
+        cancelAnimationFrame() {},
+        getComputedStyle() { return { overflowY: 'visible', paddingTop: '0px', paddingBottom: '0px' }; },
+        innerHeight: 800,
+    };
+    window.window = window;
+    window.globalThis = window;
+    const ctx = vm.createContext(window);
+    vm.runInContext(fs.readFileSync(path.join(__dirname, '..', 'screen.js'), 'utf8'), ctx, { filename: 'screen.js' });
+    assert.ok(window.folderLibrary && window.folderLibrary.__test, 'plugin must expose __test');
+    return window.folderLibrary.__test;
+}
+
+const { songCard, songRow } = load();
+
+// A raw filename with a subfolder + spaces — the kind of value song_preview
+// URL-encodes downstream, so it must reach data-fn verbatim, not pre-encoded.
+const FILENAME = 'Some Artist/A Song.sloppak';
+const SONG = { filename: FILENAME, title: 'A Song', artist: 'Some Artist' };
+
+test('song_preview helpers are exposed for the markup contract', () => {
+    assert.equal(typeof songCard, 'function');
+    assert.equal(typeof songRow, 'function');
+});
+
+test('grid card carries data-fn (raw) and a data-v3-play surface', () => {
+    const card = songCard(SONG, 'Unsorted');
+    assert.equal(card.dataset.fn, FILENAME, 'data-fn must be the raw, un-encoded filename');
+    assert.ok(card.querySelector('[data-v3-play]'), 'card must contain a [data-v3-play] surface');
+});
+
+test('list row carries data-fn (raw) and a data-v3-play surface', () => {
+    const row = songRow(SONG, 'Unsorted');
+    assert.equal(row.dataset.fn, FILENAME, 'data-fn must be the raw, un-encoded filename');
+    assert.ok(row.querySelector('[data-v3-play]'), 'row must contain a [data-v3-play] surface');
+});
+
+test('card renders without depending on any optional song metadata', () => {
+    // song_preview only needs filename; the card must build from a bare song
+    // (no duration/arrangements/stems/lyrics/tuning/year) without throwing.
+    assert.doesNotThrow(() => songCard({ filename: FILENAME }, 'Unsorted'));
+    assert.doesNotThrow(() => songRow({ filename: FILENAME }, 'Unsorted'));
+});

tests/test_midi_lyrics.py

@@ -1,282 +0,0 @@
-"""Tests for lib/midi_import.py — extract_midi_lyrics (lyrics + vocal melody).
-
-Synthetic mido.MidiFile objects are built in-memory and saved to tmp_path,
-same style as test_midi_import.py.
-
-Covers:
-  - Lyric (0x05) events on a vocal track → lyrics.json + vocal_pitch.json payloads
-  - lyric/note pairing snaps t/d to the note; midi pitch carried through
-  - lyrics with no identifiable vocal track → lyrics payload only
-  - no lyric events at all → None (import behavior unchanged)
-  - .kar '/' line-break prefixes → spec trailing '+' on the previous syllable
-  - .kar '-' hyphen joins pass through untouched
-  - space-delimited syllable streams gain '-' joins
-  - '@'-metadata tokens dropped; Text-event (0x01) fallback on vocal-ish tracks
-  - Text events on non-vocal tracks are NOT treated as lyrics
-  - unpaired lyric durations run to the next syllable, capped at 2.0 s
-  - format-0 mixed-channel file pairs only the vocal-program channel
-  - vocal GM program (52-54 / 85-87) detection without a track name
-  - audio_offset applied to both payloads
-"""
-
-import pytest
-import mido
-
-from midi_import import extract_midi_lyrics
-
-
-TPB = 480  # ticks per beat; default 120 BPM → 480 ticks = 0.5 s
-
-
-def _save(mid: mido.MidiFile, tmp_path, name: str = "test.mid") -> str:
-    p = tmp_path / name
-    mid.save(str(p))
-    return str(p)
-
-
-def _vocal_file(tmp_path, *, track_name="Vocals", program=None, meta="lyrics",
-                syllables=("Hel-", "lo", "world")):
-    """Type-1 file: conductor + one melody track carrying notes with a lyric
-    event at each note-on. Notes: 60, 62, 64, each one beat (0.5 s) long,
-    back to back."""
-    mid = mido.MidiFile(type=1, ticks_per_beat=TPB)
-    conductor = mido.MidiTrack()
-    mid.tracks.append(conductor)
-    conductor.append(mido.MetaMessage("set_tempo", tempo=500000, time=0))
-
-    tr = mido.MidiTrack()
-    mid.tracks.append(tr)
-    if track_name:
-        tr.append(mido.MetaMessage("track_name", name=track_name, time=0))
-    if program is not None:
-        tr.append(mido.Message("program_change", channel=0, program=program, time=0))
-    for i, syl in enumerate(syllables):
-        tr.append(mido.MetaMessage(meta, text=syl, time=0))
-        tr.append(mido.Message("note_on", channel=0, note=60 + 2 * i,
-                               velocity=90, time=0))
-        tr.append(mido.Message("note_off", channel=0, note=60 + 2 * i,
-                               velocity=0, time=TPB))
-    return _save(mid, tmp_path)
-
-
-# ── both sidecars from a lyric+vocal-track file ──────────────────────────────
-
-def test_vocal_track_emits_both_payloads(tmp_path):
-    result = extract_midi_lyrics(_vocal_file(tmp_path))
-    assert result is not None
-    assert result["lyrics_source"] == "authored"
-
-    lyr = result["lyrics"]
-    assert [e["w"] for e in lyr] == ["Hel-", "lo", "world"]
-    assert [e["t"] for e in lyr] == pytest.approx([0.0, 0.5, 1.0])
-    # Paired syllables snap d to the note duration (1 beat = 0.5 s).
-    assert [e["d"] for e in lyr] == pytest.approx([0.5, 0.5, 0.5])
-
-    vp = result["vocal_pitch"]
-    assert vp is not None
-    assert vp["version"] == 1
-    assert [n["midi"] for n in vp["notes"]] == [60, 62, 64]
-    # vocal_pitch t/d mirror the matching lyrics entries (spec §7.2).
-    assert [(n["t"], n["d"]) for n in vp["notes"]] == \
-        [(e["t"], e["d"]) for e in lyr]
-
-
-def test_vocal_program_detection_without_name(tmp_path):
-    """GM program 53 (Voice Oohs) marks the track vocal even with no name."""
-    path = _vocal_file(tmp_path, track_name="", program=53)
-    result = extract_midi_lyrics(path)
-    assert result is not None
-    assert result["vocal_pitch"] is not None
-    assert [n["midi"] for n in result["vocal_pitch"]["notes"]] == [60, 62, 64]
-
-
-# ── lyrics-only fallbacks ────────────────────────────────────────────────────
-
-def test_no_vocal_track_emits_lyrics_only(tmp_path):
-    """Lyric events on a noteless track + only a piano note track → the
-    lyrics payload is emitted but vocal_pitch is None (talkies path)."""
-    mid = mido.MidiFile(type=1, ticks_per_beat=TPB)
-    conductor = mido.MidiTrack()
-    mid.tracks.append(conductor)
-    conductor.append(mido.MetaMessage("set_tempo", tempo=500000, time=0))
-
-    words = mido.MidiTrack()
-    mid.tracks.append(words)
-    words.append(mido.MetaMessage("lyrics", text="Hello ", time=0))
-    words.append(mido.MetaMessage("lyrics", text="there ", time=TPB))
-
-    piano = mido.MidiTrack()
-    mid.tracks.append(piano)
-    piano.append(mido.MetaMessage("track_name", name="Piano", time=0))
-    piano.append(mido.Message("program_change", channel=0, program=0, time=0))
-    piano.append(mido.Message("note_on", channel=0, note=48, velocity=90, time=0))
-    piano.append(mido.Message("note_off", channel=0, note=48, velocity=0, time=TPB))
-
-    result = extract_midi_lyrics(_save(mid, tmp_path))
-    assert result is not None
-    assert [e["w"] for e in result["lyrics"]] == ["Hello", "there"]
-    assert result["vocal_pitch"] is None
-
-
-def test_no_lyrics_returns_none(tmp_path):
-    """A file without lyric events changes nothing — extraction reports None."""
-    mid = mido.MidiFile(type=0, ticks_per_beat=TPB)
-    tr = mido.MidiTrack()
-    mid.tracks.append(tr)
-    tr.append(mido.Message("note_on", channel=0, note=60, velocity=90, time=0))
-    tr.append(mido.Message("note_off", channel=0, note=60, velocity=0, time=TPB))
-
-    assert extract_midi_lyrics(_save(mid, tmp_path)) is None
-
-
-def test_unpaired_duration_next_event_capped_at_2s(tmp_path):
-    """Unpaired lyric entries last until the next syllable, capped at 2.0 s."""
-    mid = mido.MidiFile(type=1, ticks_per_beat=TPB)
-    conductor = mido.MidiTrack()
-    mid.tracks.append(conductor)
-    conductor.append(mido.MetaMessage("set_tempo", tempo=500000, time=0))
-
-    words = mido.MidiTrack()
-    mid.tracks.append(words)
-    words.append(mido.MetaMessage("lyrics", text="one ", time=0))
-    words.append(mido.MetaMessage("lyrics", text="two ", time=TPB))       # +0.5 s
-    words.append(mido.MetaMessage("lyrics", text="three ", time=TPB * 8))  # +4.0 s
-
-    result = extract_midi_lyrics(_save(mid, tmp_path))
-    lyr = result["lyrics"]
-    assert lyr[0]["d"] == pytest.approx(0.5)   # gap to next syllable
-    assert lyr[1]["d"] == pytest.approx(2.0)   # 4.0 s gap capped
-    assert lyr[2]["d"] == pytest.approx(2.0)   # last entry: cap value
-
-
-# ── .kar conventions ─────────────────────────────────────────────────────────
-
-def test_kar_slash_line_break_maps_to_plus(tmp_path):
-    """A '/' prefix on a syllable marks the END of the previous line — the
-    previous syllable gains the spec's trailing '+'."""
-    path = _vocal_file(
-        tmp_path, syllables=("Hel-", "lo", "/world"))
-    result = extract_midi_lyrics(path)
-    words = [e["w"] for e in result["lyrics"]]
-    assert words == ["Hel-", "lo+", "world"]
-
-
-def test_kar_backslash_paragraph_break_maps_to_plus(tmp_path):
-    path = _vocal_file(tmp_path, syllables=("one", "\\two", "three"))
-    words = [e["w"] for e in extract_midi_lyrics(path)["lyrics"]]
-    assert words == ["one+", "two", "three"]
-
-
-def test_kar_hyphen_joins_pass_through(tmp_path):
-    """.kar hyphen suffixes already ARE the spec join marker — untouched,
-    and no extra '-' is synthesized onto hyphenless word-final syllables."""
-    path = _vocal_file(tmp_path, syllables=("beau-", "ti-", "ful", "day"))
-    words = [e["w"] for e in extract_midi_lyrics(path)["lyrics"]]
-    assert words == ["beau-", "ti-", "ful", "day"]
-
-
-def test_space_delimited_stream_gains_hyphen_joins(tmp_path):
-    """Space-delimited Lyric streams ('Hel' 'lo ' 'world') carry word
-    boundaries in whitespace — mid-word syllables gain the '-' join."""
-    path = _vocal_file(tmp_path, syllables=("Hel", "lo ", "world "))
-    words = [e["w"] for e in extract_midi_lyrics(path)["lyrics"]]
-    assert words == ["Hel-", "lo", "world"]
-
-
-def test_newline_in_lyric_event_ends_line(tmp_path):
-    path = _vocal_file(tmp_path, syllables=("one \n", "two ", "three "))
-    words = [e["w"] for e in extract_midi_lyrics(path)["lyrics"]]
-    assert words == ["one+", "two", "three"]
-
-
-# ── Text-event (0x01) fallback ───────────────────────────────────────────────
-
-def test_text_event_fallback_on_vocal_track(tmp_path):
-    """With no 0x05 events anywhere, Text events on a vocal-ish track are
-    accepted as lyrics; '@'-prefixed .kar metadata tokens are dropped."""
-    mid = mido.MidiFile(type=1, ticks_per_beat=TPB)
-    conductor = mido.MidiTrack()
-    mid.tracks.append(conductor)
-    conductor.append(mido.MetaMessage("set_tempo", tempo=500000, time=0))
-
-    tr = mido.MidiTrack()
-    mid.tracks.append(tr)
-    tr.append(mido.MetaMessage("track_name", name="Melody", time=0))
-    tr.append(mido.MetaMessage("text", text="@KMIDI KARAOKE FILE", time=0))
-    tr.append(mido.MetaMessage("text", text="@T A Song", time=0))
-    for i, syl in enumerate(("Some ", "words ")):
-        tr.append(mido.MetaMessage("text", text=syl, time=0))
-        tr.append(mido.Message("note_on", channel=0, note=64 + i, velocity=90,
-                               time=0))
-        tr.append(mido.Message("note_off", channel=0, note=64 + i, velocity=0,
-                               time=TPB))
-
-    result = extract_midi_lyrics(_save(mid, tmp_path))
-    assert result is not None
-    assert [e["w"] for e in result["lyrics"]] == ["Some", "words"]
-    assert [n["midi"] for n in result["vocal_pitch"]["notes"]] == [64, 65]
-
-
-def test_text_events_on_non_vocal_track_ignored(tmp_path):
-    """Text events on a plain instrument track (copyright notices, markers)
-    are not lyrics — extraction returns None."""
-    mid = mido.MidiFile(type=1, ticks_per_beat=TPB)
-    conductor = mido.MidiTrack()
-    mid.tracks.append(conductor)
-    conductor.append(mido.MetaMessage("set_tempo", tempo=500000, time=0))
-
-    tr = mido.MidiTrack()
-    mid.tracks.append(tr)
-    tr.append(mido.MetaMessage("track_name", name="Guitar", time=0))
-    tr.append(mido.MetaMessage("text", text="Copyright 2026", time=0))
-    tr.append(mido.Message("note_on", channel=0, note=52, velocity=90, time=0))
-    tr.append(mido.Message("note_off", channel=0, note=52, velocity=0, time=TPB))
-
-    assert extract_midi_lyrics(_save(mid, tmp_path)) is None
-
-
-# ── format-0 channel isolation ───────────────────────────────────────────────
-
-def test_format0_pairs_only_vocal_program_channel(tmp_path):
-    """Format-0 file mixing a vocal-program channel with an accompaniment
-    channel: only the vocal channel's notes feed vocal_pitch."""
-    mid = mido.MidiFile(type=0, ticks_per_beat=TPB)
-    tr = mido.MidiTrack()
-    mid.tracks.append(tr)
-    tr.append(mido.Message("program_change", channel=0, program=53, time=0))  # Voice Oohs
-    tr.append(mido.Message("program_change", channel=1, program=0, time=0))   # Piano
-    # Simultaneous piano note that must NOT be paired.
-    tr.append(mido.Message("note_on", channel=1, note=40, velocity=90, time=0))
-    tr.append(mido.MetaMessage("lyrics", text="la ", time=0))
-    tr.append(mido.Message("note_on", channel=0, note=67, velocity=90, time=0))
-    tr.append(mido.Message("note_off", channel=0, note=67, velocity=0, time=TPB))
-    tr.append(mido.Message("note_off", channel=1, note=40, velocity=0, time=0))
-
-    result = extract_midi_lyrics(_save(mid, tmp_path))
-    assert result is not None
-    assert [n["midi"] for n in result["vocal_pitch"]["notes"]] == [67]
-
-
-def test_format0_without_vocal_channel_is_lyrics_only(tmp_path):
-    """Format-0 with lyrics but no vocal program/name: the merged note soup
-    cannot be trusted as a melody — lyrics.json only."""
-    mid = mido.MidiFile(type=0, ticks_per_beat=TPB)
-    tr = mido.MidiTrack()
-    mid.tracks.append(tr)
-    tr.append(mido.Message("program_change", channel=0, program=0, time=0))
-    tr.append(mido.MetaMessage("lyrics", text="la ", time=0))
-    tr.append(mido.Message("note_on", channel=0, note=60, velocity=90, time=0))
-    tr.append(mido.Message("note_off", channel=0, note=60, velocity=0, time=TPB))
-
-    result = extract_midi_lyrics(_save(mid, tmp_path))
-    assert result is not None
-    assert len(result["lyrics"]) == 1
-    assert result["vocal_pitch"] is None
-
-
-# ── audio_offset ─────────────────────────────────────────────────────────────
-
-def test_audio_offset_applied_to_both_payloads(tmp_path):
-    result = extract_midi_lyrics(_vocal_file(tmp_path), audio_offset=1.5)
-    assert result["lyrics"][0]["t"] == pytest.approx(1.5)
-    assert result["vocal_pitch"]["notes"][0]["t"] == pytest.approx(1.5)