Sanctum: A Secure, AI-Powered Journal

Sanctum is a privacy-focused, offline-first journal designed to keep your thoughts safe and your experience distraction-free. It combines strong local encryption, clean architecture, and a foundation for intelligent features without compromising user control.

This isn't just another notes app. It's a quiet space for your thoughts.

Why Sanctum?

In a landscape filled with generic note-taking apps, Sanctum is built around a few core principles:

• Private by default: No cloud sync, no account required.
• Secure by design: Data is encrypted locally before being stored or synced.
• Offline-first architecture: Data lives on-device and is synced only when appropriate.
• Modular and scalable: Built with long-term maintainability and feature isolation in mind.
• Prepared for meaningful AI: Future features will focus on assistance, not intrusion.

Architecture Overview

Sanctum is structured using a multi-module, feature-based layout. Core principles include:

• Separation of concerns between model, data, and feature layers.
• Scalable architecture, ready for growing feature sets.
• Each feature is separated into an -api and -implementation module.
• Offline-first with optional sync, fully under user control.

This structure keeps features isolated, improves testability, and makes dependency management more explicit.

Tech Stack

Area	Tech Used
UI	Jetpack Compose, Material 3
Architecture	MVVM + Clean Multi-Module
Persistence	Room + Protobuf
Background Work	WorkManager
Serialization	Kotlinx Serialization
Dependency Injection	Hilt (w/ KSP)
AI Foundation	Prepared for local NLP features
Gradle	Version Catalog, Convention Plugins
Testing	Robolectric, Turbine, Truth

Testing Strategy

Sanctum avoids mocking libraries like MockK in favor of realistic test doubles. Tests use actual implementations or handcrafted fakes with test-only hooks. This approach helps:

• Exercise more production code.
• Avoid brittle mocks.
• Encourage contract-based architecture.

System Requirements

• Android Studio Hedgehog or newer
• JVM 17

Setup

Update pre-hook path

/scripts contains shared pre-hooks for certain checks & validations. To change your local hooks path, need to run following command:

git config --local core.hooksPath scripts
chmod +x scripts/pre-commit
chmod +x scripts/pre-push

Run spotless

To apply spotless run this command:

./gradlew spotlessApply --init-script gradle/init.gradle.kts --no-configuration-cache