Settings → Robot voice: a checkbox and a voice dropdown. When on, every finished sentence is spoken back
(sentences, not words: TTS needs context for its intonation). speak(text) is the single entry point, so a
future conversational mode can reuse the same voice.
- Providers, both on this computer only: Piper (offline neural TTS run by the engine on the CPU; six
LibriTTS-R speakers offered as "Offline voice A–F") and the browser's own voices, restricted to
localService === true (some browsers synthesise "online" voices on a server — never offered).
- backend/rudder-engine/tts.go: POST /api/rudder/tts (text → audio/wav, 1–2000 characters, one synthesis
at a time), GET /api/rudder/tts/voices, POST /api/rudder/duck. The spoken text is never logged, only
its length. Piper 2023.11.14-2 (MIT) bundles ONNX Runtime 1.14.1: no telemetry client; a synthesis
traced with strace made 0 network calls. ~150 MB RAM; a 10.7 s sentence rendered in 2.2 s on CPU.
- While the robot speaks through loudspeakers, the engine feeds the transcriber silence, so it never
transcribes itself (and that silence is not mistaken for a dead mic). With a Bluetooth headset or
headphones it keeps listening — pausing would only lose the person's words.
- setup-runtime.sh: Piper and the en_US-libritts_r-medium voice (CC BY 4.0), pinned by SHA-256.
- Verified in Firefox against a dev server: dropdown lists A–F, each finished sentence is synthesised
(200 audio/wav) between duck on/off, zero requests to any other host.
Rudder is the first plugin that isn't a map: it shows that one plugin-designs/ folder, developed live
in the Plugin Studio, can ship as a desktop app with its own local backend.
- plugin-designs/rudder-voice: <rudder-voice> element. Words stream into the end of a text area while
you type/paste anywhere (typing holds the stream; nothing duplicated or lost). Mic picker with
hot-plug, 3-second mic test, plain-language errors, info panel, privacy-safe debug report.
meta.json declares "targets": ["desktop"].
- backend/rudder-engine (Go): supervises NVIDIA NeMo-Speech.cpp (ggml, CPU) with the Nemotron 3.5 ASR
Streaming GGUF over a loopback WebSocket; records with parec/pw-record only while recording; recovers
dead Bluetooth mic links (reopen -> CVSD voice profile -> optional RUDDER_BT_RESET) and starts
headsets on CVSD. No telemetry: traced with strace, zero sockets/DNS while transcribing.
- Privacy: log lines redact MAC addresses and the home folder, transcripts are never logged, Host check
against DNS rebinding, CORS only for the desktop webview, random API key for the speech server.
- internal/backend-dev-plugin.mjs + vite.config.js: `bun run dev` starts built plugin backends and
proxies /api/<name> same-origin, so a plugin calls the same API in the studio and on desktop.
- backend/rudder-engine/setup-runtime.sh: fetches the runtime and model pinned by SHA-256.
Not yet: the Tauri desktop build (sidecar) and the PocketBase word-correction table.
