Typlx Grammar Keyboard

Android custom keyboard (IME) with a grammar-fix button. Uses configurable OpenAI-compatible LLM APIs for grammar and spelling correction. Part of the Typlx open-source grammar-checking suite.

Features

• Grammar Fix Button -- tap to send the current input field text to an LLM for grammar and spelling correction
• Configurable API -- works with any OpenAI-compatible chat completions endpoint
• Secure Storage -- API tokens stored using Android EncryptedSharedPreferences
• Material3 Settings -- clean Jetpack Compose settings screen for API configuration

Architecture

app/src/main/kotlin/com/typlx/keyboard/
├── GrammarKeyboardService.kt  — InputMethodService with grammar-fix toolbar
├── GrammarService.kt          — OkHttp client for /chat/completions
├── SettingsActivity.kt        — Jetpack Compose settings screen (launcher activity)
└── PreferencesManager.kt      — SharedPreferences + EncryptedSharedPreferences wrapper

How it works

1. User enables the Typlx keyboard in Android Settings.
2. The keyboard displays a Fix Grammar toolbar button.
3. On tap, GrammarKeyboardService reads the full text from the focused input field via InputConnection.
4. GrammarService POSTs to {apiUrl}/chat/completions with temperature=0.3 and a 30 s timeout.
5. The original text is selected and replaced with the corrected version.

API Contract

POST {apiUrl}/chat/completions
Authorization: Bearer {token}
Content-Type: application/json

{
  "model": "{model}",
  "messages": [
    {"role": "system", "content": "Fix grammar and spelling in the following text. Return only the corrected text, nothing else. Preserve the original language, tone, and formatting."},
    {"role": "user", "content": "{text}"}
  ],
  "temperature": 0.3
}

Compatible with OpenAI, Ollama (http://10.0.2.2:11434), LM Studio, and any /v1/chat/completions server.

Setup

Prerequisites

• Android Studio Hedgehog (2023.1.1) or later
• JDK 11+
• Android SDK 34

Build

# First time: generate the Gradle wrapper binary
gradle wrapper --gradle-version 8.7

./gradlew assembleDebug

Install

adb install app/build/outputs/apk/debug/app-debug.apk

Enable the Keyboard

1. Launch the Typlx Keyboard app — it opens the settings screen directly.
2. Tap Enable Typlx Keyboard in System Settings and toggle it on.
3. Open any text field, tap the globe/keyboard-switcher icon, and select Typlx Keyboard.

Configure API

In the settings screen (or via Settings → Language & Input → Typlx Keyboard):

Field	Default
API URL	https://api.openai.com
Model	gpt-4o-mini
API Token	(empty — required)

Tokens are stored with EncryptedSharedPreferences backed by the Android Keystore.

Tech Stack

• Kotlin 1.9 · minSdk 24 · targetSdk 34
• OkHttp 4.12 for HTTP
• Jetpack Compose + Material 3 for all UI
• AndroidX Security Crypto for credential encryption
• Kotlin Coroutines + SupervisorJob scoped to the IME service

License

See LICENSE for details.