Initial commit: pwweb - PipeWire WebUI

C++ backend with SSE streaming (reuses qpwgraph PipeWire callbacks).
Svelte frontend with custom SVG canvas for port-level connections.

Features:
- Live PipeWire graph via SSE
- Drag output->input port to connect
- Double-click or select+Delete to disconnect
- Node positions saved to localStorage
- Pan (drag bg) and zoom (scroll)
- Port type coloring (audio=green, midi=red, video=blue)

frontend/src/App.svelte

@@ -0,0 +1,14 @@
+<script lang="ts">
+  import GraphCanvas from './components/GraphCanvas.svelte';
+</script>
+
+<GraphCanvas />
+
+<style>
+  :global(body) {
+    margin: 0;
+    padding: 0;
+    overflow: hidden;
+    background: #14141e;
+  }
+</style>

frontend/src/app.css

@@ -0,0 +1,53 @@
+*, *::before, *::after {
+  box-sizing: border-box;
+}
+
+html, body {
+  margin: 0;
+  padding: 0;
+  width: 100%;
+  height: 100%;
+  overflow: hidden;
+  background: #1a1a2e;
+  color: #ccc;
+  font-family: monospace;
+}
+
+/* Force xyflow dark theme */
+:root {
+  --xy-background-color: #1a1a2e;
+  --xy-node-background-color: #1e1e2e;
+  --xy-node-border-color: #555;
+  --xy-edge-stroke-color: #888;
+  --xy-handle-background-color: #888;
+  --xy-handle-border-color: #555;
+  --xy-attribution-background-color: rgba(0,0,0,0.5);
+}
+
+.svelte-flow {
+  background: #1a1a2e !important;
+}
+
+.svelte-flow__edge-path {
+  stroke-linecap: round;
+}
+
+.svelte-flow__controls button {
+  background: #2a2a3e !important;
+  color: #aaa !important;
+  border: 1px solid #444 !important;
+  fill: #aaa !important;
+}
+
+.svelte-flow__controls button:hover {
+  background: #3a3a4e !important;
+}
+
+.svelte-flow__minimap {
+  background: #1a1a2e !important;
+  border: 1px solid #444 !important;
+}
+
+.svelte-flow__background {
+  background: #1a1a2e;
+}

frontend/src/assets/svelte.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" aria-hidden="true" role="img" class="iconify iconify--logos" width="26.6" height="32" preserveAspectRatio="xMidYMid meet" viewBox="0 0 256 308"><path fill="#FF3E00" d="M239.682 40.707C211.113-.182 154.69-12.301 113.895 13.69L42.247 59.356a82.198 82.198 0 0 0-37.135 55.056a86.566 86.566 0 0 0 8.536 55.576a82.425 82.425 0 0 0-12.296 30.719a87.596 87.596 0 0 0 14.964 66.244c28.574 40.893 84.997 53.007 125.787 27.016l71.648-45.664a82.182 82.182 0 0 0 37.135-55.057a86.601 86.601 0 0 0-8.53-55.577a82.409 82.409 0 0 0 12.29-30.718a87.573 87.573 0 0 0-14.963-66.244"></path><path fill="#FFF" d="M106.889 270.841c-23.102 6.007-47.497-3.036-61.103-22.648a52.685 52.685 0 0 1-9.003-39.85a49.978 49.978 0 0 1 1.713-6.693l1.35-4.115l3.671 2.697a92.447 92.447 0 0 0 28.036 14.007l2.663.808l-.245 2.659a16.067 16.067 0 0 0 2.89 10.656a17.143 17.143 0 0 0 18.397 6.828a15.786 15.786 0 0 0 4.403-1.935l71.67-45.672a14.922 14.922 0 0 0 6.734-9.977a15.923 15.923 0 0 0-2.713-12.011a17.156 17.156 0 0 0-18.404-6.832a15.78 15.78 0 0 0-4.396 1.933l-27.35 17.434a52.298 52.298 0 0 1-14.553 6.391c-23.101 6.007-47.497-3.036-61.101-22.649a52.681 52.681 0 0 1-9.004-39.849a49.428 49.428 0 0 1 22.34-33.114l71.664-45.677a52.218 52.218 0 0 1 14.563-6.398c23.101-6.007 47.497 3.036 61.101 22.648a52.685 52.685 0 0 1 9.004 39.85a50.559 50.559 0 0 1-1.713 6.692l-1.35 4.116l-3.67-2.693a92.373 92.373 0 0 0-28.037-14.013l-2.664-.809l.246-2.658a16.099 16.099 0 0 0-2.89-10.656a17.143 17.143 0 0 0-18.398-6.828a15.786 15.786 0 0 0-4.402 1.935l-71.67 45.674a14.898 14.898 0 0 0-6.73 9.975a15.9 15.9 0 0 0 2.709 12.012a17.156 17.156 0 0 0 18.404 6.832a15.841 15.841 0 0 0 4.402-1.935l27.345-17.427a52.147 52.147 0 0 1 14.552-6.397c23.101-6.006 47.497 3.037 61.102 22.65a52.681 52.681 0 0 1 9.003 39.848a49.453 49.453 0 0 1-22.34 33.12l-71.664 45.673a52.218 52.218 0 0 1-14.563 6.398"></path></svg>

frontend/src/components/GraphCanvas.svelte

@@ -0,0 +1,496 @@
+<script lang="ts">
+  import { onMount, onDestroy } from 'svelte';
+  import {
+    nodes, ports, links, connected,
+    portById,
+    initGraph, destroyGraph,
+    connectPorts, disconnectPorts,
+  } from '../lib/stores';
+  import type { Node, Port, Link } from '../lib/types';
+
+  // Viewport state
+  let viewBox = $state({ x: -100, y: -40, w: 1200, h: 700 });
+  let dragging = $state<{ type: string; startX: number; startY: number; origX: number; origY: number; nodeId?: string } | null>(null);
+  let connecting = $state<{ outputPortId: number; outputX: number; outputY: number; mouseX: number; mouseY: number; portType: string } | null>(null);
+  let hoveredPort = $state<number | null>(null);
+  let selectedEdge = $state<string | null>(null);
+  let svgEl: SVGElement | null = null;
+
+  // Node positions
+  const POS_KEY = 'pwweb_pos';
+  function loadPos(): Record<string, { x: number; y: number }> {
+    try { return JSON.parse(localStorage.getItem(POS_KEY) || '{}'); } catch { return {}; }
+  }
+  function savePos(pos: Record<string, { x: number; y: number }>) {
+    try { localStorage.setItem(POS_KEY, JSON.stringify(pos)); } catch {}
+  }
+  let nodePositions = $state(loadPos());
+
+  // Layout defaults
+  function getDefaultPositions(n: Node[]): Record<string, { x: number; y: number }> {
+    const out = n.filter(nd => nd.mode === 'output');
+    const inp = n.filter(nd => nd.mode === 'input');
+    const other = n.filter(nd => nd.mode !== 'output' && nd.mode !== 'input');
+    const result: Record<string, { x: number; y: number }> = {};
+    let i = 0;
+    for (const nd of out) {
+      if (!result[nd.id]) result[nd.id] = { x: 0, y: (i % 8) * 100 };
+      i++;
+    }
+    i = 0;
+    for (const nd of other) {
+      if (!result[nd.id]) result[nd.id] = { x: 320, y: (i % 8) * 100 };
+      i++;
+    }
+    i = 0;
+    for (const nd of inp) {
+      if (!result[nd.id]) result[nd.id] = { x: 640, y: (i % 8) * 100 };
+      i++;
+    }
+    return result;
+  }
+
+  // Compute layout
+  let graphNodes = $derived.by(() => {
+    const n = $nodes;
+    const p = $ports;
+    const portMap = new Map<number, Port>();
+    for (const port of p) portMap.set(port.id, port);
+
+    const defaults = getDefaultPositions(n);
+    const pos = { ...defaults, ...nodePositions };
+
+    return n.map(nd => {
+      const ndPorts = nd.port_ids.map(pid => portMap.get(pid)).filter(Boolean) as Port[];
+      const inPorts = ndPorts.filter(pp => pp.mode === 'input');
+      const outPorts = ndPorts.filter(pp => pp.mode === 'output');
+      const nodePos = pos[String(nd.id)] || { x: 0, y: 0 };
+
+      // Compute node dimensions
+      const maxPorts = Math.max(inPorts.length, outPorts.length, 1);
+      const headerH = 24;
+      const portH = 18;
+      const height = headerH + maxPorts * portH + 6;
+      const width = 200;
+
+      // Compute port positions
+      const portPositions = new Map<number, { x: number; y: number }>();
+      let yi = headerH;
+      for (const port of inPorts) {
+        portPositions.set(port.id, { x: nodePos.x, y: nodePos.y + yi + portH / 2 });
+        yi += portH;
+      }
+      let yo = headerH;
+      for (const port of outPorts) {
+        portPositions.set(port.id, { x: nodePos.x + width, y: nodePos.y + yo + portH / 2 });
+        yo += portH;
+      }
+
+      return {
+        ...nd,
+        x: nodePos.x,
+        y: nodePos.y,
+        width,
+        height,
+        inPorts,
+        outPorts,
+        portPositions,
+      };
+    });
+  });
+
+  let graphLinks = $derived.by(() => {
+    const l = $links;
+    const p = $ports;
+    const portMap = new Map<number, Port>();
+    for (const port of p) portMap.set(port.id, port);
+
+    return l.map(link => {
+      const outPort = portMap.get(link.output_port_id);
+      const inPort = portMap.get(link.input_port_id);
+      return { ...link, outPort, inPort };
+    }).filter(l => l.outPort && l.inPort) as Array<Link & { outPort: Port; inPort: Port }>;
+  });
+
+  // Port positions lookup across all nodes
+  function getPortPos(portId: number): { x: number; y: number } | null {
+    for (const node of graphNodes) {
+      const pos = node.portPositions.get(portId);
+      if (pos) return pos;
+    }
+    return null;
+  }
+
+  function portColor(pt: string): string {
+    switch (pt) {
+      case 'audio': return '#4a9';
+      case 'midi':  return '#a44';
+      case 'video': return '#49a';
+      default:      return '#999';
+    }
+  }
+
+  function shortName(name: string): string {
+    const idx = name.lastIndexOf(':');
+    return idx >= 0 ? name.substring(idx + 1) : name;
+  }
+
+  // Bezier curve between two points
+  function bezierPath(x1: number, y1: number, x2: number, y2: number): string {
+    const dx = Math.abs(x2 - x1) * 0.5;
+    return `M ${x1} ${y1} C ${x1 + dx} ${y1}, ${x2 - dx} ${y2}, ${x2} ${y2}`;
+  }
+
+  // Mouse events
+  function svgPoint(e: MouseEvent): { x: number; y: number } {
+    if (!svgEl) return { x: e.clientX, y: e.clientY };
+    const pt = (svgEl as any).createSVGPoint();
+    pt.x = e.clientX;
+    pt.y = e.clientY;
+    const ctm = (svgEl as SVGGraphicsElement).getScreenCTM();
+    if (!ctm) return { x: e.clientX, y: e.clientY };
+    const svgP = pt.matrixTransform(ctm.inverse());
+    return { x: svgP.x, y: svgP.y };
+  }
+
+  function onMouseDown(e: MouseEvent) {
+    const pt = svgPoint(e);
+    const target = e.target as HTMLElement;
+
+    // Check if clicking on a port circle
+    if (target.classList.contains('port-circle')) {
+      const portId = Number(target.dataset.portId);
+      const port = $portById.get(portId);
+      if (port && port.mode === 'output') {
+        const pos = getPortPos(portId);
+        if (pos) {
+          connecting = {
+            outputPortId: portId,
+            outputX: pos.x,
+            outputY: pos.y,
+            mouseX: pt.x,
+            mouseY: pt.y,
+            portType: port.port_type,
+          };
+        }
+      }
+      return;
+    }
+
+    // Check if clicking on a node header (to drag)
+    if (target.classList.contains('node-header') || target.closest('.node-group')) {
+      const nodeGroup = target.closest('.node-group') as HTMLElement;
+      if (nodeGroup) {
+        const nodeId = nodeGroup.dataset.nodeId!;
+        const nd = graphNodes.find(n => String(n.id) === nodeId);
+        if (nd) {
+          dragging = {
+            type: 'node',
+            startX: pt.x,
+            startY: pt.y,
+            origX: nd.x,
+            origY: nd.y,
+            nodeId,
+          };
+        }
+        return;
+      }
+    }
+
+    // Check if clicking on an edge
+    if (target.classList.contains('edge-path')) {
+      selectedEdge = target.dataset.edgeId || null;
+      return;
+    }
+
+    // Click on background: pan
+    selectedEdge = null;
+    dragging = { type: 'pan', startX: e.clientX, startY: e.clientY, origX: viewBox.x, origY: viewBox.y };
+  }
+
+  function onMouseMove(e: MouseEvent) {
+    if (!dragging && !connecting) return;
+    const pt = svgPoint(e);
+
+    if (connecting) {
+      connecting.mouseX = pt.x;
+      connecting.mouseY = pt.y;
+      return;
+    }
+
+    if (!dragging) return;
+
+    if (dragging.type === 'node' && dragging.nodeId) {
+      const dx = pt.x - dragging.startX;
+      const dy = pt.y - dragging.startY;
+      nodePositions[dragging.nodeId] = {
+        x: dragging.origX + dx,
+        y: dragging.origY + dy,
+      };
+      nodePositions = nodePositions; // trigger reactivity
+    } else if (dragging.type === 'pan') {
+      const dx = (e.clientX - dragging.startX) * (viewBox.w / (svgEl?.clientWidth || 1));
+      const dy = (e.clientY - dragging.startY) * (viewBox.h / (svgEl?.clientHeight || 1));
+      viewBox.x = dragging.origX - dx;
+      viewBox.y = dragging.origY - dy;
+    }
+  }
+
+  function onMouseUp(e: MouseEvent) {
+    if (connecting) {
+      const target = e.target as HTMLElement;
+      if (target.classList.contains('port-circle')) {
+        const inputPortId = Number(target.dataset.portId);
+        const port = $portById.get(inputPortId);
+        if (port && port.mode === 'input' && port.port_type === connecting.portType) {
+          connectPorts(connecting.outputPortId, inputPortId);
+        }
+      }
+      connecting = null;
+    }
+
+    if (dragging?.type === 'node' && dragging.nodeId) {
+      savePos(nodePositions);
+    }
+
+    dragging = null;
+  }
+
+  function onWheel(e: WheelEvent) {
+    e.preventDefault();
+    const pt = svgPoint(e);
+    const factor = e.deltaY > 0 ? 1.1 : 0.9;
+    const nw = viewBox.w * factor;
+    const nh = viewBox.h * factor;
+    viewBox.x = pt.x - (pt.x - viewBox.x) * factor;
+    viewBox.y = pt.y - (pt.y - viewBox.y) * factor;
+    viewBox.w = nw;
+    viewBox.h = nh;
+  }
+
+  function onEdgeDblClick(e: MouseEvent) {
+    const target = e.target as HTMLElement;
+    if (target.classList.contains('edge-path')) {
+      const edgeId = target.dataset.edgeId;
+      const link = $links.find(l => String(l.id) === edgeId);
+      if (link) {
+        disconnectPorts(link.output_port_id, link.input_port_id);
+      }
+    }
+  }
+
+  function onKey(e: KeyboardEvent) {
+    if ((e.key === 'Delete' || e.key === 'Backspace') && selectedEdge) {
+      const link = $links.find(l => String(l.id) === selectedEdge);
+      if (link) {
+        disconnectPorts(link.output_port_id, link.input_port_id);
+        selectedEdge = null;
+      }
+    }
+  }
+
+  onMount(() => { initGraph(); });
+  onDestroy(() => { destroyGraph(); });
+</script>
+
+<svelte:window onkeydown={onKey} />
+
+<div class="wrap">
+  <div class="bar">
+    <span class="dot" class:on={$connected}></span>
+    <span>{$connected ? 'Connected' : 'Disconnected'}</span>
+    <span class="st">{$nodes.length} nodes | {$ports.length} ports | {$links.length} links</span>
+    <span class="help">Drag port->port to connect. Dbl-click wire to disconnect. Scroll to zoom. Drag bg to pan.</span>
+  </div>
+
+  <!-- svelte-ignore a11y_no_static_element_interactions -->
+  <svg
+    bind:this={svgEl}
+    viewBox="{viewBox.x} {viewBox.y} {viewBox.w} {viewBox.h}"
+    onmousedown={onMouseDown}
+    onmousemove={onMouseMove}
+    onmouseup={onMouseUp}
+    onwheel={onWheel}
+    ondblclick={onEdgeDblClick}
+    class="canvas"
+  >
+    <!-- Edges -->
+    {#each graphLinks as link (link.id)}
+      {@const outPos = getPortPos(link.output_port_id)}
+      {@const inPos = getPortPos(link.input_port_id)}
+      {#if outPos && inPos}
+        {@const color = portColor(link.outPort.port_type)}
+        <path
+          d={bezierPath(outPos.x, outPos.y, inPos.x, inPos.y)}
+          stroke={selectedEdge === String(link.id) ? '#fff' : color}
+          stroke-width={selectedEdge === String(link.id) ? 3 : 2}
+          fill="none"
+          class="edge-path"
+          data-edge-id={String(link.id)}
+        />
+      {/if}
+    {/each}
+
+    <!-- Connecting line (while dragging) -->
+    {#if connecting}
+      <path
+        d={bezierPath(connecting.outputX, connecting.outputY, connecting.mouseX, connecting.mouseY)}
+        stroke={portColor(connecting.portType)}
+        stroke-width="2"
+        stroke-dasharray="6 3"
+        fill="none"
+        opacity="0.8"
+      />
+    {/if}
+
+    <!-- Nodes -->
+    {#each graphNodes as nd (nd.id)}
+      {@const headerColor = nd.mode === 'output' ? '#2a3a2a' : nd.mode === 'input' ? '#3a2a2a' : '#2a2a3a'}
+      {@const borderColor = nd.mode === 'output' ? '#4a9' : nd.mode === 'input' ? '#a44' : '#555'}
+
+      <g class="node-group" data-node-id={String(nd.id)}>
+        <!-- Background -->
+        <rect
+          x={nd.x} y={nd.y}
+          width={nd.width} height={nd.height}
+          rx="5" ry="5"
+          fill="#1e1e2e"
+          stroke={borderColor}
+          stroke-width="1"
+        />
+
+        <!-- Header -->
+        <rect
+          x={nd.x} y={nd.y}
+          width={nd.width} height="24"
+          rx="5" ry="5"
+          fill={headerColor}
+          class="node-header"
+        />
+        <rect
+          x={nd.x} y={nd.y + 18}
+          width={nd.width} height="6"
+          fill={headerColor}
+        />
+        <text
+          x={nd.x + 6} y={nd.y + 16}
+          font-size="11" font-family="monospace"
+          fill="#ddd" font-weight="bold"
+        >
+          {nd.name.length > 28 ? nd.name.substring(0, 25) + '...' : nd.name}
+        </text>
+
+        <!-- Input ports (left side) -->
+        {#each nd.inPorts as port, i (port.id)}
+          {@const py = nd.y + 24 + i * 18 + 9}
+          <circle
+            cx={nd.x} cy={py}
+            r="5"
+            fill={portColor(port.port_type)}
+            stroke="#fff"
+            stroke-width={hoveredPort === port.id ? 2 : 0.5}
+            class="port-circle"
+            data-port-id={String(port.id)}
+            onmouseenter={() => { hoveredPort = port.id; }}
+            onmouseleave={() => { hoveredPort = null; }}
+          />
+          <text
+            x={nd.x + 10} y={py + 4}
+            font-size="10" font-family="monospace"
+            fill="#aaa"
+          >{shortName(port.name)}</text>
+        {/each}
+
+        <!-- Output ports (right side) -->
+        {#each nd.outPorts as port, i (port.id)}
+          {@const py = nd.y + 24 + i * 18 + 9}
+          <text
+            x={nd.x + nd.width - 10} y={py + 4}
+            font-size="10" font-family="monospace"
+            fill="#aaa"
+            text-anchor="end"
+          >{shortName(port.name)}</text>
+          <circle
+            cx={nd.x + nd.width} cy={py}
+            r="5"
+            fill={portColor(port.port_type)}
+            stroke="#fff"
+            stroke-width={hoveredPort === port.id ? 2 : 0.5}
+            class="port-circle"
+            data-port-id={String(port.id)}
+            onmouseenter={() => { hoveredPort = port.id; }}
+            onmouseleave={() => { hoveredPort = null; }}
+          />
+        {/each}
+      </g>
+    {/each}
+  </svg>
+</div>
+
+<style>
+  .wrap {
+    width: 100%;
+    height: 100vh;
+    background: #1a1a2e;
+    position: relative;
+    overflow: hidden;
+  }
+
+  .canvas {
+    width: 100%;
+    height: 100%;
+    display: block;
+    cursor: default;
+  }
+
+  .bar {
+    position: absolute;
+    top: 0;
+    left: 0;
+    right: 0;
+    z-index: 10;
+    display: flex;
+    align-items: center;
+    gap: 8px;
+    padding: 6px 16px;
+    background: rgba(20, 20, 30, 0.95);
+    border-bottom: 1px solid #333;
+    font-size: 12px;
+    color: #aaa;
+    font-family: monospace;
+  }
+
+  .dot {
+    width: 8px;
+    height: 8px;
+    border-radius: 50%;
+    background: #a44;
+    display: inline-block;
+  }
+  .dot.on { background: #4a9; }
+
+  .st { margin-left: auto; color: #666; }
+  .help { color: #555; font-size: 11px; margin-left: 16px; }
+
+  .port-circle {
+    cursor: crosshair;
+  }
+  .port-circle:hover {
+    filter: brightness(1.5);
+  }
+
+  .edge-path {
+    cursor: pointer;
+    pointer-events: stroke;
+  }
+  .edge-path:hover {
+    stroke-width: 4;
+  }
+
+  .node-header {
+    cursor: grab;
+  }
+  .node-group:hover rect {
+    filter: brightness(1.1);
+  }
+</style>

frontend/src/components/PortNode.svelte

@@ -0,0 +1,137 @@
+<script lang="ts">
+  import { Handle, Position } from '@xyflow/svelte';
+  import type { Port } from '../lib/types';
+
+  let { data }: { data: {
+    label: string;
+    nodeType: string;
+    mode: string;
+    inputs: Port[];
+    outputs: Port[];
+  } } = $props();
+
+  function portColor(portType: string): string {
+    switch (portType) {
+      case 'audio': return '#4a9';
+      case 'midi':  return '#a44';
+      case 'video': return '#49a';
+      default:      return '#999';
+    }
+  }
+
+  function shortName(name: string): string {
+    const idx = name.lastIndexOf(':');
+    return idx >= 0 ? name.substring(idx + 1) : name;
+  }
+</script>
+
+<div class="port-node" class:output-node={data.mode === 'output'} class:input-node={data.mode === 'input'}>
+  <div class="node-header">
+    <span class="node-type-label">{data.nodeType}</span>
+    <span class="node-label" title={data.label}>{data.label}</span>
+  </div>
+
+  <div class="node-body">
+    {#if data.inputs.length > 0}
+      <div class="ports-column">
+        {#each data.inputs as port (port.id)}
+          <div class="port" style="--pc: {portColor(port.port_type)}">
+            <Handle
+              type="target"
+              position={Position.Left}
+              id={String(port.id)}
+              class="port-handle"
+              style="background:{portColor(port.port_type)};border-color:{portColor(port.port_type)}"
+            />
+            <span class="port-name">{shortName(port.name)}</span>
+          </div>
+        {/each}
+      </div>
+    {/if}
+
+    {#if data.outputs.length > 0}
+      <div class="ports-column">
+        {#each data.outputs as port (port.id)}
+          <div class="port out" style="--pc: {portColor(port.port_type)}">
+            <span class="port-name">{shortName(port.name)}</span>
+            <Handle
+              type="source"
+              position={Position.Right}
+              id={String(port.id)}
+              class="port-handle"
+              style="background:{portColor(port.port_type)};border-color:{portColor(port.port_type)}"
+            />
+          </div>
+        {/each}
+      </div>
+    {/if}
+  </div>
+</div>
+
+<style>
+  .port-node {
+    background: #1e1e2e;
+    border: 1px solid #555;
+    border-radius: 6px;
+    min-width: 150px;
+    font-family: monospace;
+    font-size: 12px;
+    color: #ccc;
+    box-shadow: 0 2px 8px rgba(0,0,0,0.5);
+  }
+  .output-node { border-color: #4a9; }
+  .input-node { border-color: #a44; }
+
+  .node-header {
+    background: #2a2a3e;
+    padding: 5px 8px;
+    display: flex;
+    align-items: center;
+    gap: 6px;
+    border-bottom: 1px solid #444;
+    border-radius: 6px 6px 0 0;
+  }
+  .node-type-label {
+    font-size: 9px;
+    color: #777;
+    text-transform: uppercase;
+  }
+  .node-label {
+    font-weight: bold;
+    white-space: nowrap;
+    overflow: hidden;
+    text-overflow: ellipsis;
+    color: #ddd;
+    flex: 1;
+    font-size: 11px;
+  }
+
+  .node-body { padding: 2px 0; }
+  .ports-column { display: flex; flex-direction: column; }
+  .ports-column + .ports-column { border-top: 1px solid #333; }
+
+  .port {
+    display: flex;
+    align-items: center;
+    padding: 3px 6px;
+    position: relative;
+  }
+  .port.out { justify-content: flex-end; }
+
+  .port-name {
+    font-size: 11px;
+    color: #aaa;
+  }
+
+  :global(.port-handle) {
+    width: 8px !important;
+    height: 8px !important;
+    min-width: 8px !important;
+    min-height: 8px !important;
+    border: 1px solid #888 !important;
+    border-radius: 50% !important;
+    position: relative !important;
+    top: 0 !important;
+    transform: none !important;
+  }
+</style>

frontend/src/lib/Counter.svelte

@@ -0,0 +1,10 @@
+<script lang="ts">
+  let count: number = $state(0)
+  const increment = () => {
+    count += 1
+  }
+</script>
+
+<button class="counter" onclick={increment}>
+  Count is {count}
+</button>

frontend/src/lib/stores.ts

@@ -0,0 +1,64 @@
+import { writable, derived, get } from 'svelte/store';
+import type { Node, Port, Link, GraphMessage } from './types';
+import { subscribe, connectPorts, disconnectPorts } from './ws';
+
+// Raw graph stores
+export const nodes = writable<Node[]>([]);
+export const ports = writable<Port[]>([]);
+export const links = writable<Link[]>([]);
+export const connected = writable(false);
+
+// Port lookup map
+export const portById = derived(ports, ($ports) => {
+  const map = new Map<number, Port>();
+  for (const p of $ports) map.set(p.id, p);
+  return map;
+});
+
+// Node lookup map
+export const nodeById = derived(nodes, ($nodes) => {
+  const map = new Map<number, Node>();
+  for (const n of $nodes) map.set(n.id, n);
+  return map;
+});
+
+// Initialize: fetch via REST immediately, then subscribe to WS for updates
+let unsubscribe: (() => void) | null = null;
+
+function applyGraph(graph: GraphMessage) {
+  nodes.set(graph.nodes);
+  ports.set(graph.ports);
+  links.set(graph.links);
+  connected.set(true);
+}
+
+export async function initGraph() {
+  if (unsubscribe) return;
+
+  // 1. Fetch initial state via REST API (works immediately, no WS needed)
+  try {
+    const res = await fetch('/api/graph');
+    if (res.ok) {
+      const graph: GraphMessage = await res.json();
+      applyGraph(graph);
+    }
+  } catch (e) {
+    console.warn('[graph] REST fetch failed:', e);
+  }
+
+  // 2. Subscribe to WebSocket for live updates
+  unsubscribe = subscribe((graph: GraphMessage) => {
+    applyGraph(graph);
+  });
+}
+
+export function destroyGraph() {
+  if (unsubscribe) {
+    unsubscribe();
+    unsubscribe = null;
+    connected.set(false);
+  }
+}
+
+// Re-export connection functions
+export { connectPorts, disconnectPorts };

frontend/src/lib/types.ts

@@ -0,0 +1,47 @@
+// Types matching the C++ backend JSON protocol
+
+export interface Port {
+  id: number;
+  node_id: number;
+  name: string;
+  mode: 'input' | 'output' | 'duplex' | 'none';
+  port_type: 'audio' | 'midi' | 'video' | 'other';
+  flags: number;
+}
+
+export interface Node {
+  id: number;
+  name: string;
+  nick: string;
+  media_name: string;
+  mode: 'input' | 'output' | 'duplex' | 'none';
+  node_type: string;
+  port_ids: number[];
+}
+
+export interface Link {
+  id: number;
+  output_port_id: number;
+  input_port_id: number;
+}
+
+export interface GraphMessage {
+  type: 'graph';
+  nodes: Node[];
+  ports: Port[];
+  links: Link[];
+}
+
+export interface ConnectMessage {
+  type: 'connect';
+  output_port_id: number;
+  input_port_id: number;
+}
+
+export interface DisconnectMessage {
+  type: 'disconnect';
+  output_port_id: number;
+  input_port_id: number;
+}
+
+export type WsMessage = ConnectMessage | DisconnectMessage;

frontend/src/lib/ws.ts

@@ -0,0 +1,83 @@
+import type { GraphMessage } from './types';
+
+type GraphListener = (graph: GraphMessage) => void;
+
+let es: EventSource | null = null;
+let listeners: GraphListener[] = [];
+let reconnectTimer: ReturnType<typeof setTimeout> | null = null;
+
+function connect() {
+  if (es && es.readyState === EventSource.OPEN) return;
+
+  const url = '/events';
+  console.log('[sse] connecting to', url);
+  es = new EventSource(url);
+
+  es.onopen = () => {
+    console.log('[sse] connected');
+  };
+
+  es.onmessage = (event) => {
+    try {
+      const data = JSON.parse(event.data);
+      if (data.type === 'graph') {
+        for (const fn of listeners) {
+          fn(data as GraphMessage);
+        }
+      }
+    } catch (e) {
+      console.warn('[sse] parse error:', e);
+    }
+  };
+
+  es.onerror = () => {
+    console.log('[sse] disconnected, reconnecting in 2s...');
+    es?.close();
+    es = null;
+    if (!reconnectTimer && listeners.length > 0) {
+      reconnectTimer = setTimeout(() => {
+        reconnectTimer = null;
+        connect();
+      }, 2000);
+    }
+  };
+}
+
+export function subscribe(fn: GraphListener): () => void {
+  listeners.push(fn);
+  connect();
+  return () => {
+    listeners = listeners.filter(l => l !== fn);
+    if (listeners.length === 0 && es) {
+      es.close();
+      es = null;
+      if (reconnectTimer) {
+        clearTimeout(reconnectTimer);
+        reconnectTimer = null;
+      }
+    }
+  };
+}
+
+async function postCommand(endpoint: string, outputPortId: number, inputPortId: number) {
+  try {
+    await fetch(endpoint, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: JSON.stringify({
+        output_port_id: outputPortId,
+        input_port_id: inputPortId,
+      }),
+    });
+  } catch (e) {
+    console.error('[api] POST', endpoint, 'failed:', e);
+  }
+}
+
+export function connectPorts(outputPortId: number, inputPortId: number) {
+  postCommand('/api/connect', outputPortId, inputPortId);
+}
+
+export function disconnectPorts(outputPortId: number, inputPortId: number) {
+  postCommand('/api/disconnect', outputPortId, inputPortId);
+}

frontend/src/main.ts

@@ -0,0 +1,9 @@
+import { mount } from 'svelte'
+import './app.css'
+import App from './App.svelte'
+
+const app = mount(App, {
+  target: document.getElementById('app')!,
+})
+
+export default app