zebra-spaces: classic chimes — guest-joined + hand-raised

Two Web Audio synthesised tones, no asset shipping required:
- playToneJoin: C5 -> E5 ascending major-third chime (~340ms total),
  fires on every peer-joined. Server broadcasts peer-joined to
  everyone except the joiner via broadcastExcept, so existing members
  always hear it for new arrivals only.
- playToneRaise: single A5 triangle blip (~260ms), fires on
  hand-raised UNLESS it's the raiser's own hand (server broadcasts
  hand-raised to all so we filter on m.uuid !== myUUID).

Tones share a lazily-instantiated AudioContext (the user already
gestured to enter the room, autoplay policy is satisfied). Skipped
when document.hidden so background tabs stay quiet. Short
exponential attack + decay envelope avoids click artifacts.

web/zebra-spaces.html

@@ -2886,6 +2886,56 @@ function startMeter(uuid, stream){
 }
 function stopMeter(uuid){ meterCtl.delete(uuid); }
 
+/* ==================================================================
+ * notification tones — synthesised via Web Audio so no asset needed.
+ *
+ *   playToneJoin()  — ascending major-third chime (523→659 Hz):
+ *                     friendly 'welcome' signature
+ *   playToneRaise() — single bell-like 880 Hz tone: gentle attention
+ *
+ * A single shared AudioContext is lazily created on first use; the
+ * user already gestured to enter the room (clicked 'enter'), so the
+ * autoplay policy is satisfied. Each tone uses a short exponential
+ * fade-out to avoid click artifacts.
+ *
+ * Tones are skipped if the page is hidden (background tab) — the
+ * idea is to notify the LIVE user, not interrupt them when they
+ * stepped away.
+ * ================================================================== */
+let _toneCtx = null;
+function _toneCtxGet(){
+  if (_toneCtx) return _toneCtx;
+  try { _toneCtx = new (window.AudioContext || window.webkitAudioContext)(); } catch(_){ return null; }
+  return _toneCtx;
+}
+function playToneBlip(freq, durationMs, type){
+  if (typeof document !== 'undefined' && document.hidden) return;
+  const ctx = _toneCtxGet(); if (!ctx) return;
+  try {
+    const t0 = ctx.currentTime;
+    const osc = ctx.createOscillator();
+    const gain = ctx.createGain();
+    osc.type = type || 'sine';
+    osc.frequency.value = freq;
+    osc.connect(gain); gain.connect(ctx.destination);
+    /* short attack, exponential decay → no click on start or end */
+    gain.gain.setValueAtTime(0.0001, t0);
+    gain.gain.exponentialRampToValueAtTime(0.12, t0 + 0.012);
+    gain.gain.exponentialRampToValueAtTime(0.0001, t0 + durationMs / 1000);
+    osc.start(t0);
+    osc.stop(t0 + durationMs / 1000 + 0.02);
+  } catch(_){}
+}
+function playToneJoin(){
+  /* C5 → E5 ascending major third — a classic 'someone arrived' lift */
+  playToneBlip(523.25, 140, 'sine');
+  setTimeout(() => playToneBlip(659.25, 200, 'sine'), 120);
+}
+function playToneRaise(){
+  /* single A5 bell-ish tone — light, attention-getting */
+  playToneBlip(880.0, 260, 'triangle');
+}
+
 /* ==================================================================
  * room state mirror (server is source of truth, we mirror locally for
  * rendering). updated by welcome / peer-joined / peer-left / state /
@@ -3075,6 +3125,10 @@ async function handleSignal(raw){
     case 'peer-joined':
       members.set(m.uuid, { uuid:m.uuid, pubkey:m.pubkey, handle:m.handle, role:m.role, joined_at: Date.now()/1000 });
       { const pub = pubHexFromMsg(m, 'pubkey'); logLine('', idTag(m.uuid, pub)+' joined as '+m.role); }
+      /* classic 'guest joined' chime — server only sends peer-joined
+       * to OTHER members (broadcastExcept), so we're always notifying
+       * the existing room about a new arrival. */
+      playToneJoin();
       /* re-announce our mic state so the new arrival's UI reflects
        * reality. Server-side mic-state-req covers welcome timing; this
        * covers the standard 'a new peer joined while we were already
@@ -3153,6 +3207,9 @@ async function handleSignal(raw){
     case 'hand-raised':
       handraise.add(m.uuid); renderRoom();
       { const pub = pubHexFromMsg(m, 'pubkey'); logLine('', idTag(m.uuid, pub)+' raised hand'); }
+      /* attention bell for mods — skip if it's our own hand going up
+       * (server broadcasts to everyone including the raiser). */
+      if (m.uuid !== myUUID) playToneRaise();
       break;
     case 'hand-lowered':
       handraise.delete(m.uuid); renderRoom();
@@ -4029,8 +4086,8 @@ logLine('', 'ready — pick a handle, type a rendezvous code, enter the space');
 
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