feat: verse-based lyric grouping and active-verse tracking

group_into_verses() splits LRC lyrics on empty lines or timestamp gaps
>3.5s; find_active_verse() returns the current verse lines and active
index with INTER_VERSE_CAP (8s) cap on the last line of each verse.
ControlState.set_lyrics() now pre-computes verses; current() exposes
verse_lines and verse_active instead of the old 5-line lyric_context.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

luz-musica.py

@@ -96,6 +96,7 @@ class ControlState:
     def set_lyrics(self, lyrics: list[tuple[float, str]]) -> None:
         with self._lock:
             self._lyrics = lyrics
+            self._verses = group_into_verses(lyrics)
 
     def set_position(self, position: float) -> None:
         with self._lock:
@@ -103,40 +104,17 @@ class ControlState:
 
     def current(self) -> dict[str, object]:
         with self._lock:
-            lyrics   = getattr(self, "_lyrics",   [])
+            verses   = getattr(self, "_verses",   [])
             position = getattr(self, "_position", 0.0)
-            MAX_DISPLAY = 5.0
+            verse_lines, verse_active = find_active_verse(verses, position)
-
+            line = verse_lines[verse_active] if verse_active >= 0 and verse_lines else ""
-            active_idx = -1
-            line = ""
-            for i, (ts, text) in enumerate(lyrics):
-                if ts > position:
-                    break
-                next_ts = lyrics[i + 1][0] if i + 1 < len(lyrics) else ts + MAX_DISPLAY
-                if position <= min(next_ts, ts + MAX_DISPLAY):
-                    active_idx = i
-                    line = text
-                else:
-                    active_idx = -1
-                    line = ""
-
-            # Build 5-line context from non-empty lyrics, centered on active
-            context: list[dict[str, object]] = []
-            if active_idx >= 0 and line:
-                display_idxs = [i for i, (_, t) in enumerate(lyrics) if t.strip()]
-                if active_idx in display_idxs:
-                    pos = display_idxs.index(active_idx)
-                    for offset in range(-2, 3):
-                        di = pos + offset
-                        t = lyrics[display_idxs[di]][1] if 0 <= di < len(display_idxs) else ""
-                        context.append({"text": t, "offset": offset})
-
             return {
                 "art_url":      getattr(self, "_art_url", None),
                 "rgb":          list(getattr(self, "_rgb",  [0, 200, 255])),
                 "rgb2":         list(getattr(self, "_rgb2", [255, 0, 150])),
                 "lyric_line":   line,
-                "lyric_context": context,
+                "verse_lines":  verse_lines,
+                "verse_active": verse_active,
             }
 
 
@@ -221,6 +199,9 @@ def start_control_server() -> ThreadingHTTPServer:
     return server
 
 
+VERSE_GAP_SECS  = 3.5   # gap between lines that splits a verse
+INTER_VERSE_CAP = 8.0   # how long to keep last line of a verse visible
+
 _LRC_TS = re.compile(r'\[(\d{1,2}):(\d{2}(?:\.\d+)?)\]')
 
 
@@ -255,6 +236,46 @@ def clean_title(title: str) -> str:
     return t
 
 
+def group_into_verses(
+    lyrics: list[tuple[float, str]],
+) -> list[list[tuple[float, str]]]:
+    """Split non-empty lyrics into verses on empty LRC lines or large timestamp gaps."""
+    verses: list[list[tuple[float, str]]] = []
+    current: list[tuple[float, str]] = []
+    for ts, text in lyrics:
+        if not text.strip():
+            if current:
+                verses.append(current)
+                current = []
+            continue
+        if current and (ts - current[-1][0]) > VERSE_GAP_SECS:
+            verses.append(current)
+            current = []
+        current.append((ts, text))
+    if current:
+        verses.append(current)
+    return verses
+
+
+def find_active_verse(
+    verses: list[list[tuple[float, str]]],
+    position: float,
+) -> tuple[list[str], int]:
+    """Return (verse_text_lines, active_index) or ([], -1) when in a gap."""
+    for v_idx, verse in enumerate(verses):
+        for l_idx, (ts, _) in enumerate(verse):
+            if ts > position:
+                break
+            if l_idx + 1 < len(verse):
+                deadline = verse[l_idx + 1][0]
+            else:
+                nxt = verses[v_idx + 1][0][0] if v_idx + 1 < len(verses) else ts + INTER_VERSE_CAP
+                deadline = min(nxt, ts + INTER_VERSE_CAP)
+            if position <= deadline:
+                return [t for _, t in verse], l_idx
+    return [], -1
+
+
 def fetch_lyrics(artist: str, title: str) -> list[tuple[float, str]]:
     if not artist or not title:
         return []