feat: Introduce ntfy.sh message polling, content fetching with caching, and microphone input monitoring.

engine/mic.py

@@ -0,0 +1,62 @@
+"""
+Microphone input monitor — standalone, no internal dependencies.
+Gracefully degrades if sounddevice/numpy are unavailable.
+"""
+
+import atexit
+
+try:
+    import sounddevice as _sd
+    import numpy as _np
+    _HAS_MIC = True
+except Exception:
+    _HAS_MIC = False
+
+
+class MicMonitor:
+    """Background mic stream that exposes current RMS dB level."""
+
+    def __init__(self, threshold_db=50):
+        self.threshold_db = threshold_db
+        self._db = -99.0
+        self._stream = None
+
+    @property
+    def available(self):
+        """True if sounddevice is importable."""
+        return _HAS_MIC
+
+    @property
+    def db(self):
+        """Current RMS dB level."""
+        return self._db
+
+    @property
+    def excess(self):
+        """dB above threshold (clamped to 0)."""
+        return max(0.0, self._db - self.threshold_db)
+
+    def start(self):
+        """Start background mic stream. Returns True on success, False/None otherwise."""
+        if not _HAS_MIC:
+            return None
+        def _cb(indata, frames, t, status):
+            rms = float(_np.sqrt(_np.mean(indata ** 2)))
+            self._db = 20 * _np.log10(rms) if rms > 0 else -99.0
+        try:
+            self._stream = _sd.InputStream(
+                callback=_cb, channels=1, samplerate=44100, blocksize=2048)
+            self._stream.start()
+            atexit.register(self.stop)
+            return True
+        except Exception:
+            return False
+
+    def stop(self):
+        """Stop the mic stream if running."""
+        if self._stream:
+            try:
+                self._stream.stop()
+            except Exception:
+                pass
+            self._stream = None