SilentPulse

Privacy-first SMS & messaging app with an offline voice assistant for hands-free drive mode.

Forked from QKSMS and rebuilt for corporate and security-sensitive environments where no data may leave the device to any third party.

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What is SilentPulse?

SilentPulse is a drop-in replacement for the Android stock SMS app. On top of that it ships a fully offline, always-on voice assistant you activate hands-free while driving. Every feature works without internet — except a small set of explicitly whitelisted privacy-respecting APIs (weather, navigation ETA, stock prices, and optional AI search). Google is never contacted.

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Voice Assistant — Drive Mode

Wake word

Say "Computer" at any time while the assistant is running. The Vosk on-device keyword spotter hears it silently (zero beeps, minimal CPU). The mic then hands off to Android's on-device Speech Recognizer and plays a single beep so you know it is ready.

Supported voice commands

Category	Example phrases
Time	"What time is it" · "What time is it in Tokyo" · "Time in New York"
Weather	"What's the weather" · "Weather in Berlin" · "Weather on the corridor"
Navigation	"Navigate to 123 Main Street" · "Directions to the airport" · "Stop navigation"
Drive time	"How long to downtown" · "Drive time to Chicago"
Notifications	"Read my notifications" · "Read my email" — then: Skip / Reply / Repeat / Dismiss / Stop
Music	"Play music" · "Play [artist/song]" · "Resume"
Audiobooks	"Listen to book" · "Open voice"
Stock prices	"Price of bitcoin" · "Price of AAPL" · "Price of gold"
General questions	"What is the capital of France?" · "Who invented the telephone?"
App control	"Open Maps" · "Close Spotify"
Cross-app logging	"Computer, Microcore, log weight 220 pounds"
Help	"Help" · "What can you do?"

Architecture — two-phase listening

Phase 1 — Vosk keyword spotter runs continuously, constrained to the grammar ["computer", "[unk]"]. It reads raw PCM via AudioRecord — zero beeps, zero SpeechRecognizer restarts, minimal battery drain.

Phase 2 — When Vosk hears "Computer" it releases the mic and hands off to Android SpeechRecognizer (EXTRA_PREFER_OFFLINE=true) for a single free-form utterance. The recognizer plays its natural beep — this is the "ready" signal the user hears.

The transcript then flows through a routing chain:

Handler	Backend
TimeHandler	IANA timezone DB — fully offline, 150+ city aliases, Levenshtein fuzzy match
WeatherCommandHandler	open-meteo.com / wttr.in — open source, no API key
NavigationCommandHandler	OSRM for ETA; launches OsmAnd / Maps for turn-by-turn
DriveTimeHandler	router.project-osrm.org
NotificationReaderHandler	Reads notification shade; inline reply via RemoteInput
MusicCommandHandler	MediaBrowser / MediaController, local library
StockQueryHandler	Yahoo Finance unofficial API
GeneralQueryHandler	DuckDuckGo instant answers → Wikipedia → Brave fallback
BraveSearchHandler	Optional AI search summariser (user-supplied API key)
CommandRouter	Cross-app broadcast dispatch with Levenshtein fuzzy app-name matching

All TTS uses Android's on-device TextToSpeech engine with automatic language/locale detection. No cloud speech of any kind.

Cross-app voice broadcast protocol

Third-party apps can register as voice targets. SilentPulse:

1. Discovers registered apps via PackageManager (ASSISTANT_CAPABLE intent filter)
2. Strips the app name from the command and dispatches an EXECUTE_COMMAND broadcast
3. The target app replies with a TTS_REPLY broadcast; SilentPulse speaks it aloud
4. Supports multi-turn disambiguation — if the target replies with candidates, SilentPulse asks the user to clarify, then re-dispatches with the resolved intent

Example: "Computer, Microcore, log weight 220 pounds" — SilentPulse routes "log weight 220 pounds" to the Microcore health app, which logs the measurement and replies "Logged weight at 220 pounds."

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Privacy Architecture

Core principle: if it touches Google, it is blocked.

Network security

network_security_config.xml acts as a domain-level TLS firewall:

• base-config trusts zero certificate authorities — any unlisted domain fails at TLS handshake
• Only explicitly whitelisted privacy-respecting domains can connect:

Domain	Purpose
open-meteo.com	Weather (open source, no key)
wttr.in	Weather fallback (open source, no key)
api.duckduckgo.com	General instant answers (no key)
en.wikipedia.org	Knowledge lookups (no key)
nominatim.openstreetmap.org	Geocoding (OpenStreetMap, no key)
router.project-osrm.org	Drive-time routing (OSRM open source)
query1/2.finance.yahoo.com	Stock prices (unofficial)
api.search.brave.com	AI search summariser (optional — user-supplied key)

What is explicitly absent

• No Firebase of any kind (no Crashlytics, Analytics, FCM, Remote Config, Performance)
• No Google Play Services network calls — ML Kit runs in fully bundled/embedded mode only
• No crash or event reporting (Sentry, Datadog, Amplitude, Mixpanel, Segment…)
• No advertising SDKs
• No cloud TTS or cloud STT — all speech processing is on-device only
• No log shipping — Timber logs go to a local file only, never off-device
• No A/B testing or feature flag services
• No referral or attribution tracking

Build variants

Variant	Description
noAnalytics (default)	No Firebase, no analytics, no crash reporting. This is the only variant that should be distributed.
withAnalytics	Legacy flavor kept for historical reference — do not distribute.

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Building

Requires Java 17 and NDK 28.2.13676358.

# Debug APK — sideload via ADB for testing
./gradlew :presentation:assembleNoAnalyticsDebug

# Release APK — uses production keystore if secrets are set, otherwise debug key
./gradlew :presentation:assembleNoAnalyticsRelease

Installing via ADB

adb install presentation/build/outputs/apk/noAnalytics/debug/presentation-noAnalytics-debug.apk

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CI / CD

Every push to master runs Build and Release:

1. Installs NDK 28.2.13676358
2. Builds both noAnalytics-debug and noAnalytics-release APKs
3. Falls back to a freshly generated debug keystore when production signing secrets are absent
4. Publishes a GitHub pre-release with both APKs attached

Always check the Actions tab after pushing. If a run fails, expand the failed step. Common failure modes are documented in .github/copilot-instructions.md.

Production signing secrets

Set in Settings → Secrets → Actions on the repository:

Secret	Value
KEYSTORE_BASE64	base64 -w0 release.jks
KEYSTORE_PASSWORD	Store password
KEY_ALIAS	Key alias
KEY_PASSWORD	Key password

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Project structure

android-smsmms/       MMS library (fork of klinker41/android-smsmms)
common/               Shared utilities
data/                 Realm database, repositories
domain/               Use-cases / business logic
presentation/         UI + Voice Assistant
  └─ feature/
       ├─ assistant/
       │    ├─ VoiceAssistantService.kt       Foreground service — wake-word → route → TTS
       │    ├─ VoskWakeWordDetector.kt        Phase 1: always-on Vosk keyword spotter
       │    ├─ CommandRouter.kt              Cross-app broadcast dispatch
       │    ├─ TimeHandler.kt               Offline timezone resolution (150+ cities)
       │    ├─ WeatherCommandHandler.kt     Weather (open-meteo / wttr.in)
       │    ├─ NavigationCommandHandler.kt  Turn-by-turn + ETA
       │    ├─ DriveTimeHandler.kt          OSRM drive-time queries
       │    ├─ NotificationReaderHandler.kt Hands-free notification reading + reply
       │    ├─ StockQueryHandler.kt         Real-time stock / crypto prices
       │    ├─ GeneralQueryHandler.kt       DuckDuckGo + Wikipedia + Brave fallback
       │    ├─ BraveSearchHandler.kt        Optional AI search summariser
       │    └─ MusicCommandHandler.kt       Local media playback control
       └─ drivemode/
            ├─ DriveModeService.kt          Core drive-mode notification reader
            ├─ AndroidSttEngine.kt          On-device SpeechRecognizer wrapper
            └─ VoiceActivityDetector.kt     VAD for push-to-listen

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License

Released under the GNU General Public License v3.0 (GPLv3) — see LICENSE.

Original QKSMS by Moez Bhatti. SilentPulse additions copyright their respective authors.