flow-core

libflow

libflow is a Rust library that powers a cloud-first voice dictation engine with AI formatting, app-aware writing modes, and self-learning corrections. It is designed to be used directly from Rust or via the bundled C-compatible FFI layer for Swift integration.

Features

• Audio capture via CPAL with 16 kHz mono PCM output
• Pluggable transcription and completion providers (OpenAI, Anthropic)
• Writing modes that adapt formatting and tone per app
• Voice shortcuts and learned typo corrections
• SQLite-backed storage for persistence and stats
• C ABI for Swift or other native integrations

Quick start (Rust)

use flow_core::{
    AudioCapture, CompletionRequest, OpenAICompletionProvider, OpenAITranscriptionProvider,
    TranscriptionRequest, WritingMode,
};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut capture = AudioCapture::new()?;
    capture.start()?;

    // Record some audio, then stop and fetch bytes.
    let audio = capture.stop()?;

    let transcription_provider = OpenAITranscriptionProvider::new(None);
    let completion_provider = OpenAICompletionProvider::new(None);

    let transcription = transcription_provider
        .transcribe(TranscriptionRequest::new(audio, 16_000))
        .await?;

    let completion = completion_provider
        .complete(CompletionRequest::new(
            transcription.text,
            WritingMode::Casual,
        ))
        .await?;

    println!("{}", completion.text);
    Ok(())
}

Set OPENAI_API_KEY (or ANTHROPIC_API_KEY when using Anthropic) in the environment, or configure providers via the FFI helpers.

FFI usage

The C ABI is exposed in src/ffi.rs and provides a small set of lifecycle, recording, and formatting calls, including:

• flow_init / flow_destroy
• flow_start_recording / flow_stop_recording
• flow_transcribe
• flow_set_api_key / flow_set_completion_provider

Flow is a voice dictation app with AI formatting, shortcuts, and learning.

This directory contains the Rust core engine used by the app. The rest of the app lives in the parent directory.