feat: add mobile web frontend with AudioWorklet recording

web/audio-processor.js

@@ -0,0 +1,73 @@
+/**
+ * AudioWorklet processor for VoicePaste.
+ *
+ * Captures raw Float32 PCM from the microphone, accumulates samples into
+ * ~200ms frames, and posts them to the main thread for resampling + WS send.
+ *
+ * Communication:
+ *   Main → Processor: { command: "start" | "stop" }
+ *   Processor → Main: { type: "audio", samples: Float32Array, sampleRate: number }
+ */
+class AudioProcessor extends AudioWorkletProcessor {
+  constructor() {
+    super();
+    this.recording = false;
+    this.buffer = [];
+    this.bufferLen = 0;
+    // ~200ms worth of samples at current sample rate
+    // sampleRate is a global in AudioWorkletGlobalScope
+    this.frameSize = Math.floor(sampleRate * 0.2);
+
+    this.port.onmessage = (e) => {
+      if (e.data.command === "start") {
+        this.recording = true;
+        this.buffer = [];
+        this.bufferLen = 0;
+      } else if (e.data.command === "stop") {
+        // Flush remaining samples
+        if (this.bufferLen > 0) {
+          this._flush();
+        }
+        this.recording = false;
+      }
+    };
+  }
+
+  process(inputs) {
+    if (!this.recording) return true;
+
+    const input = inputs[0];
+    if (!input || !input[0]) return true;
+
+    // Mono channel 0
+    const channelData = input[0];
+    this.buffer.push(new Float32Array(channelData));
+    this.bufferLen += channelData.length;
+
+    if (this.bufferLen >= this.frameSize) {
+      this._flush();
+    }
+
+    return true;
+  }
+
+  _flush() {
+    // Merge buffer chunks into a single Float32Array
+    const merged = new Float32Array(this.bufferLen);
+    let offset = 0;
+    for (const chunk of this.buffer) {
+      merged.set(chunk, offset);
+      offset += chunk.length;
+    }
+
+    this.port.postMessage(
+      { type: "audio", samples: merged, sampleRate: sampleRate },
+      [merged.buffer] // Transfer ownership for zero-copy
+    );
+
+    this.buffer = [];
+    this.bufferLen = 0;
+  }
+}
+
+registerProcessor("audio-processor", AudioProcessor);