Replace QML CAVA polling with SSE server for smooth bars

DataSource fork+exec was limited to ~1fps. Now cava pipes into a Python
SSE server (port 5555) and the HTML connects directly via EventSource,
getting updates at up to 60fps without QML overhead.

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

plugin/contents/ui/cava-server.py

@@ -0,0 +1,45 @@
+#!/usr/bin/env python3
+"""
+Reads CAVA ASCII output from stdin and streams it to the wallpaper
+via Server-Sent Events on http://127.0.0.1:5555.
+Run as: cava -p cava.conf | python3 cava-server.py
+"""
+import sys
+import threading
+import time
+from http.server import HTTPServer, BaseHTTPRequestHandler
+
+latest = ""
+lock   = threading.Lock()
+
+class Handler(BaseHTTPRequestHandler):
+    def do_GET(self):
+        self.send_response(200)
+        self.send_header("Content-Type",  "text/event-stream")
+        self.send_header("Cache-Control", "no-cache")
+        self.send_header("Access-Control-Allow-Origin", "*")
+        self.end_headers()
+        last = None
+        try:
+            while True:
+                with lock:
+                    cur = latest
+                if cur and cur != last:
+                    self.wfile.write(f"data: {cur}\n\n".encode())
+                    self.wfile.flush()
+                    last = cur
+                time.sleep(0.016)   # cap at ~60fps
+        except Exception:
+            pass
+
+    def log_message(self, *args):
+        pass
+
+def serve():
+    HTTPServer(("127.0.0.1", 5555), Handler).serve_forever()
+
+threading.Thread(target=serve, daemon=True).start()
+
+for line in sys.stdin:
+    with lock:
+        latest = line.strip()

plugin/contents/ui/cava-start.sh

@@ -1,9 +1,7 @@
 #!/usr/bin/env bash
-# Kill any previous instance tied to this config
 pkill -f "cava -p.*skeledance" 2>/dev/null
+pkill -f "cava-server.py"      2>/dev/null
 sleep 0.2
 
-CONF="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)/cava.conf"
+DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
-cava -p "$CONF" | while IFS= read -r line; do
+cava -p "$DIR/cava.conf" | python3 "$DIR/cava-server.py"
-    printf '%s\n' "$line" > /tmp/skeledance_bars
-done

plugin/contents/ui/dancer.html

@@ -886,7 +886,7 @@ for (let i = 0; i < VU_COUNT; i++) {
   vuBars.push(bar);
 }
 
-// Called by QML with semicolon-separated CAVA values (0–100 per bar)
+// Called with semicolon-separated CAVA values (0–100 per bar)
 function updateBars(raw) {
   if (!isPlaying) return;
   const vals = raw.split(';');
@@ -898,6 +898,13 @@ function updateBars(raw) {
   });
 }
 
+// Connect to CAVA SSE server (started by cava-start.sh via QML)
+(function connectCava() {
+  const sse = new EventSource('http://127.0.0.1:5555');
+  sse.onmessage = e => { if (e.data) updateBars(e.data); };
+  sse.onerror   = () => { sse.close(); setTimeout(connectCava, 3000); };
+})();
+
 /* ============================================================
    FLOATING MUSIC NOTES
    ============================================================ */

plugin/contents/ui/main.qml

@@ -16,6 +16,7 @@ WallpaperItem {
         settings {
             javascriptEnabled: true
             localContentCanAccessFileUrls: true
+            localContentCanAccessRemoteUrls: true
             localStorageEnabled: false
         }
 
@@ -51,18 +52,4 @@ WallpaperItem {
         }
     }
 
-    // Polls CAVA bars at ~60fps
-    Plasma5Support.DataSource {
-        id: cavaSource
-        engine: "executable"
-        connectedSources: ["cat /tmp/skeledance_bars 2>/dev/null || echo ''"]
-        interval: 80
-
-        onNewData: function(sourceName, data) {
-            var raw = data["stdout"].trim()
-            if (raw !== "") {
-                webView.runJavaScript("updateBars(" + JSON.stringify(raw) + ")")
-            }
-        }
-    }
 }