Agentic Keyboard (Lumina AI Keyboard)

An Android custom keyboard (IME) built with Jetpack Compose that pairs a standard QWERTY layout with Gemini-powered writing assistance and a fully on-device personalization engine.

Features

AI writing tools (Gemini)

• Fix Grammar — corrects spelling/grammar and explains what changed; one tap to apply.
• Proofread as you type (opt-in) — a debounced background grammar check surfaces a one-tap fix chip while you write.
• Compose — type an instruction ("tell her I'll be 20 min late, apologetic") and get the actual message drafted in your voice.
• Rewrite — restyles your draft to match your selected persona; long-press the chip to cycle personas from the keyboard.
• Continue — extends your draft mid-thought in your own style.
• Summarize — condenses long text into 1–2 sentences.
• Translate — translates between configurable source/target languages.
• Analyze Tone — detects sentiment/tone with actionable tips plus tone-matched emoji you can insert with a tap.
• Smart Replies — three context-aware responses at three lengths (short / medium / detailed).
• Clipboard intelligence — tap 📋 to paste, translate, summarize, explain in plain language, or generate replies to whatever you just copied (e.g. the message you're answering).

Every request is enriched with a locally computed personalization context (your dominant tone and most-used vocabulary), repeated identical requests are served from an in-memory cache, and starting a new action cancels the one in flight.

On-device intelligence (works offline)

• Swipe-to-type backed by a 10,000-word frequency-ranked dictionary plus your personal vocabulary, with a live gesture trail and word preview.
• Smart space bar — committing a word with space expands shortcut templates (omw → "On my way! Running late."), applies learned typo corrections, and feeds vocabulary learning. Double-tap space inserts a period.
• Auto-correction undo — backspace right after a correction restores what you typed; reverting the same rule twice deletes it.
• Learned auto-corrections — typo→fix rules are extracted automatically whenever the AI corrects your grammar, then applied locally as you type.
• Next-word prediction — an on-device bigram model learns your word pairs and predicts the next word after each space.
• Prefix predictions built from your own most-frequent words.
• Per-app personas — the keyboard remembers which persona you use in each app (Professional in email, Casual in chat).
• Shortcut templates — user-defined abbreviations that expand to full phrases.
• Command gestures — diagonal swipes over the keyboard trigger Translate / Summarize / Tone / Expand; horizontal swipes are Space/Backspace.
• Typing mechanics — auto-capitalization at sentence starts, one-shot shift with double-tap caps lock, long-press accents (é, ñ, ü…) and punctuation variants, hold-to-repeat backspace, slide-on-space cursor control, optional number row, and a mic key that hands off to your voice IME.

Privacy

• Password fields are detected automatically — AI features, logging, and learning all shut off in secure fields.
• Offline mode toggle blocks all cloud calls; local fallbacks keep the tools functional. The toggle (and all settings) persist across restarts.
• Always-on cloud request redaction — the final serialized Gemini request is sanitized immediately before transmission, replacing credential-shaped secrets, emails, phone numbers, financial identifiers, SSNs, IP addresses, URLs, and long numeric IDs with neutral markers.
• Pause learning — an incognito switch for the personalization engine.
• Data retention — writing logs auto-expire after 7/30/90 days (your choice).
• Cloud backup disabled — your typing history never leaves the device via Android backup.
• No request logging in release builds; the API key is sent as a header and redacted from debug logs.
• Style Hub export & import — serialize your personalization model to JSON (or Base64) with optional redaction of emails, phone numbers, financial numbers, IPs, URLs, and numeric IDs, then restore it on another device.
• Usage dashboard — on-device stats for auto-fixes, swipes, AI applies, and shortcut expansions.

Project layout

app/src/main/java/io/github/daddymean/agentickeyboard/
├── AgenticKeyboardApplication.kt   # App singleton exposing the Room repository
├── MainActivity.kt                 # Companion app: playground, shortcuts, Style Hub, setup guide
├── service/AgenticKeyboardService.kt  # The InputMethodService hosting the Compose keyboard
├── ui/
│   ├── AgenticKeyboardLayout.kt    # Keyboard UI: keys, AI shelf, gestures, swipe-to-type
│   └── KeyboardViewModel.kt        # State + AI orchestration + on-device learning
├── network/
│   ├── RetrofitClient.kt           # Gemini API client
│   └── CloudRedactionInterceptor.kt # Last-mile outbound privacy guard
├── db/DatabaseModels.kt            # Room entities, DAOs, repository
└── util/
    ├── CloudTextSanitizer.kt        # Pure-JVM sensitive-value redaction
    ├── SwipeToTypeEngine.kt        # Path-matching swipe decoder
    └── PersonalModelSerializer.kt  # Privacy-aware personalization export

Run locally

Prerequisites: Android Studio

1. Open the project directory in Android Studio.
2. Create a .env file in the project root and set GEMINI_API_KEY to your Gemini API key (see .env.example). Without a key the app still runs using its offline fallbacks.
3. Run the app configuration on an emulator or device.

Enable the keyboard

1. In the app, open the Setup Guide tab and tap Open System Keyboards (or go to Settings → System → Languages & input → On-screen keyboard).
2. Enable Agentic Keyboard, then switch to it via the input-method picker.

Testing

Unit tests (Robolectric, Roborazzi screenshots, and plain JUnit) live in app/src/test:

./gradlew testDebugUnitTest

Covered areas: cloud request redaction, privacy-aware export, JSON integrity, swipe-to-type decoding, and keyboard layout screenshots.