diff --git a/nodes/audio_guide.py b/nodes/audio_guide.py
index eefa608..d4254bc 100644
--- a/nodes/audio_guide.py
+++ b/nodes/audio_guide.py
@@ -180,6 +180,9 @@ def _render(rms_n, times, duration, beats, bounds, segs,
 
 
 def _summary(duration, sr, bpm, beats, segs, global_notes):
+    if not segs:
+        return (f"AUDIO GUIDE — {duration:.2f}s clip. No segments defined yet: double-click "
+                f"the waveform to add split points (each split starts a new beat).")
     lines = ["AUDIO GUIDE — align the video beats to this audio:",
              f"- duration: {duration:.2f}s  |  sample_rate: {sr} Hz"]
     if bpm:
diff --git a/nodes/audio_wave_segments.py b/nodes/audio_wave_segments.py
index 629cc5e..d970ed1 100644
--- a/nodes/audio_wave_segments.py
+++ b/nodes/audio_wave_segments.py
@@ -108,19 +108,19 @@ def _parse_range(sel, n):
 
 
 def _segments_grouped(rms_n, times, duration, fps, group_frames, user_starts, beats):
-    """Segments = user split points UNION the fixed group boundaries (every group_frames
-    frames). The group lines are hard splits, so a segment never crosses one — the last
-    segment in a group ends exactly on the group boundary (e.g. frame 721)."""
+    """Segments come ONLY from the user's split points (the 721 group lines are just clip
+    markers, NOT segments). Points = [0] + splits; a segment runs between consecutive
+    points, so N splits -> N segments (the tail after the last split is not a segment).
+    Global numbering. `group` = which 721 group each segment starts in (for reference)."""
     gstep = max(group_frames, 1) / max(fps, 1)
     gbounds, k = [], 1
-    while k * gstep < duration - 1e-6:
+    while k * gstep < duration - 1e-6:                 # for drawing + the group number only
         gbounds.append(round(k * gstep, 3)); k += 1
-    allb = sorted({round(b, 3) for b in list(user_starts) + gbounds if 0 < b < duration - 1e-6})
-    starts = [0.0] + allb
+    pts = [0.0] + sorted({round(s, 3) for s in user_starts if 0 < s < duration - 1e-6})
     stages = ["establish", "build", "peak", "settle"]
     segs, bounds = [], [0.0]
-    for i, t0 in enumerate(starts):
-        t1 = starts[i + 1] if i + 1 < len(starts) else duration
+    for i in range(len(pts) - 1):                     # exclude the tail (last point -> end)
+        t0, t1 = pts[i], pts[i + 1]
         bounds.append(round(t1, 3))
         mask = (times >= t0) & (times < t1)
         e = float(rms_n[mask].mean()) if mask.any() else 0.0
diff --git a/web/audio_wave.js b/web/audio_wave.js
index 941317e..1c97123 100644
--- a/web/audio_wave.js
+++ b/web/audio_wave.js
@@ -91,12 +91,12 @@ function setupWave(node) {
     for (let t = step; t < st.duration - 1e-6; t += step) arr.push(t);
     return arr;
   }
-  function segStarts() {                               // union of 0 + user splits + group lines
+  function segPoints() {                               // [0] + user splits (NOT the group lines)
     const set = new Set([0]);
     for (const s of st.splits) if (s > 0 && s < st.duration) set.add(Math.round(s * 100) / 100);
-    for (const g of groupBounds()) set.add(Math.round(g * 100) / 100);
     return Array.from(set).sort((a, b) => a - b);
   }
+  const nSegs = () => Math.max(0, segPoints().length - 1);  // N splits -> N segments (tail excluded)
 
   function serialize() {                               // write ONLY user splits (small + stable)
     const w = getW(node, "segments_json"); if (!w) return;
@@ -111,7 +111,7 @@ function setupWave(node) {
   function syncNotesBox() {                            // one segN: line per segment, preserve notes
     const nw = getW(node, "notes"); if (!nw) return;
     const { seg, glob } = parseNotes(nw.value);
-    const n = segStarts().length; const lines = [];
+    const n = nSegs(); const lines = [];
     for (let i = 1; i <= n; i++) lines.push(`seg${i}: ${seg[i] !== undefined ? seg[i] : ""}`);
     const val = lines.concat(glob).join("\n");
     if (nw.value !== val) { nw.value = val; nw.callback?.(val); }
@@ -127,10 +127,10 @@ function setupWave(node) {
   function draw() {
     ctx.fillStyle = "#141418"; ctx.fillRect(0, 0, canvas.width, canvas.height);
     const H = canvas.height, mid = H / 2;
-    const starts = segStarts();
+    const pts = segPoints();                            // [0, split1, split2, ...]; seg k = pts[k-1]..pts[k]
     const sel = selRange();
-    if (sel) {                                          // shade selected range
-      const a = starts[sel[0] - 1], b = sel[1] < starts.length ? starts[sel[1]] : st.duration;
+    if (sel) {                                          // shade selected segment range
+      const a = pts[sel[0] - 1], b = sel[1] < pts.length ? pts[sel[1]] : st.duration;
       if (a !== undefined) { ctx.fillStyle = "#26364f"; ctx.fillRect(t2x(a), 0, t2x(b) - t2x(a), H); }
     }
     if (st.peaks) {                                     // mirrored waveform around centre
@@ -144,11 +144,14 @@ function setupWave(node) {
     ctx.lineWidth = 1;
     const { seg } = parseNotes(getW(node, "notes")?.value);
     ctx.font = "10px monospace";
-    starts.forEach((s, i) => {                          // segment line + label top + note bottom
+    const nseg = nSegs();
+    pts.forEach((s, i) => {                              // split line; label seg i+1 (skip tail)
       const x = t2x(s);
       ctx.strokeStyle = "#7ec8a0"; ctx.beginPath(); ctx.moveTo(x, 0); ctx.lineTo(x, H); ctx.stroke();
-      ctx.fillStyle = "#fff"; ctx.fillText(`S${i + 1} ${s.toFixed(1)}s`, x + 3, 11);
-      if (seg[i + 1]) { ctx.fillStyle = "#ffd27a"; ctx.fillText(seg[i + 1].slice(0, 22), x + 3, H - 4); }
+      if (i < nseg) {
+        ctx.fillStyle = "#fff"; ctx.fillText(`S${i + 1} ${s.toFixed(1)}s`, x + 3, 11);
+        if (seg[i + 1]) { ctx.fillStyle = "#ffd27a"; ctx.fillText(seg[i + 1].slice(0, 22), x + 3, H - 4); }
+      }
     });
     ctx.strokeStyle = "#ff5a3c"; const px = t2x(st.audio.currentTime || 0);  // playhead
     ctx.beginPath(); ctx.moveTo(px, 0); ctx.lineTo(px, H); ctx.stroke();