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Saarthi AI

Built: August 8, 2026

[ GitHub ↗ ]

Saarthi ("charioteer, guide" in Hindi) is a voice assistant for Android, built for people who find a phone screen hard to read or navigate. Say things like "open WhatsApp and message Amma" or "what's on this screen," and it narrates what's there and taps through the steps itself, in your choice of 10 Indian languages, checking back with you before doing anything that can't be undone.

The agent loop

ChatRouter decides whether a spoken turn is a question, a short confirmation ("yes" answering something said earlier), or a task. Tasks go to AgentLoop, which runs on Claude Haiku 4.5 at effort: high with adaptive thinking: perceive the screen → pick a tool call → execute → narrate the step → re-perceive → repeat.

ChatRouter also carries real self-knowledge of what the agent can and can't do, so it can answer "can you do X?" honestly instead of just attempting X and failing.

Perception and the safety guard

ScreenPerception reads the current screen through SaarthiAccessibilityService (no vision model, no screenshots), the same grounding approach as Handrail. ActionExecutor carries out the chosen tool call, and IrreversibleActionGuard sits in front of every tap, checking the target node before it fires and handing back to the user instead of completing anything that looks irreversible.

LoginWallDetector catches a specific failure mode directly: the agent tapping a web-search result about an app instead of opening the app itself.

Speech

  • SarvamStreamingStt: streaming speech-to-text with VAD auto-stop, so recording ends on its own instead of waiting for a fixed timeout
  • MayaTts: streaming text-to-speech for narration, switched over from an earlier Sarvam-TTS integration once Maya's streaming endpoint held up better in practice
  • The app is localized into 10 languages, with real voice samples wired into the onboarding voice picker so you hear the actual voice before picking it

Interface

A translucent assist overlay (long-press home, backed by a real ASSIST intent handler, same as Handrail) plus a full app shell: onboarding, home, conversation history and threads, settings, and a dedicated hand-back screen for when the guard stops a task.

Stack

  • Kotlin, native Android, Jetpack Compose
  • AccessibilityService perception layer: no vision, no screenshots
  • Claude Haiku 4.5 (ClaudeClient) for routing and the agent loop
  • Sarvam streaming STT, Maya streaming TTS
  • Local on-device chat history store, no backend