Wyoming speech-to-text server for Home Assistant using NVIDIA Parakeet

Loads parakeet-mlx in-process (no HTTP hop) and serves it over the Wyoming
protocol. On an M4 Mac mini this transcribes typical voice commands in ~110ms
versus ~1150ms for a whisper.cpp large-v3 setup, with identical accuracy on a
ten-command benchmark.

Two behaviours matter beyond speed: silence returns an empty string rather
than whisper's "Thank you." hallucination, and there is no decoder context
carried between requests.

Notable implementation details, all covered by mutation-checked regression
tests:

- MLX streams are thread-local, so the model is loaded and evaluated on a
  single dedicated worker thread. Splitting those raises
  "There is no Stream(cpu, 1) in current thread".
- parakeet_mlx.load_audio() shells out to ffmpeg, which is unnecessary here
  since Wyoming delivers 16kHz mono PCM. The mel is built directly via
  get_logmel(), whose input must be float32 -- it views the complex STFT
  output as the input dtype, so anything narrower doubles the mel bin count.
- Wyoming's run loop has no except clause, so an exception escaping
  handle_event closes the connection without sending a Transcript and Home
  Assistant waits indefinitely. Failures are caught and returned as an empty
  transcript instead.

Defaults to parakeet-tdt-0.6b-v2 rather than the newer multilingual v3
because v2 emits digits ("21 degrees") where v3 spells numbers out, and
Home Assistant's local intent matching expects digits.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

uninstall.sh

@@ -0,0 +1,24 @@
+#!/usr/bin/env bash
+# Remove the wyoming-parakeet LaunchDaemon. Leaves the checkout and the
+# downloaded model in ~/.cache/huggingface alone.
+set -euo pipefail
+
+LABEL="local.wyoming-parakeet"
+PLIST="/Library/LaunchDaemons/$LABEL.plist"
+
+echo "==> Stopping $LABEL"
+sudo launchctl bootout "system/$LABEL" 2>/dev/null || echo "    (not running)"
+
+if [[ -f "$PLIST" ]]; then
+    echo "==> Removing $PLIST"
+    sudo rm -f "$PLIST"
+fi
+
+cat <<MSG
+
+Done. Not removed:
+  - this checkout, including .venv
+  - the model in ~/.cache/huggingface (delete with:
+    rm -rf ~/.cache/huggingface/hub/models--mlx-community--parakeet-tdt-0.6b-v2)
+  - the Wyoming integration in Home Assistant (remove it in the UI)
+MSG