Architecture

Module structure

nexira/
├── client-config      # Constants, AppConfig, BuildConfig
├── client-core        # Domain models, API services, interfaces
├── client-launcher    # DI wiring, file download, update, launch logic
└── client-ui          # Compose Multiplatform desktop UI

client-config

App-wide constants: server URLs, timeouts, file paths, proxy config.
Generates BuildConfig with version and build time via gmazzo/buildconfig.

client-core

Pure business logic — no UI, no DI framework dependencies.

AuthService — login, AES token decryption, SSL error detection
ServerRepository — dashboard fetch, launcher hash update cycle
SkinRepository — skin/cloak upload
HttpClientProvider — switches between secure/insecure OkHttp client at runtime
Domain models: SessionData, FileManifest, SettingsData, etc.

client-launcher

Wires everything together with Koin DI.

FileDownloadService — manifest flattening, parallel download, MD5 verification, extra.zip unpacking
LauncherService + GameCommandBuilder — assembles JVM command line for 1.7.10 / 1.12.2 / 1.21.1
UpdateService — GitHub Releases API, per-OS asset detection, SHA256 verification
CredentialsManager — AES-256-GCM encryption with PBKDF2 key derivation
ProfileManager — per-server instance profiles, favorites, last server
JavaManagerService — downloads Bellsoft JDK bundles per Minecraft version

client-ui

Compose Multiplatform desktop UI.

AppLayout / AppRoot — root composition, window management, auto-login
DashboardScreen — server grid, launch control panel
RightPanel — login/account panel, news feed
TrayManager — dorkbox/SystemTray wrapper
LauncherController — launch pipeline state machine (Idle → Prepare → Downloading → GameRunning)

Key design decisions

HttpClientProvider instead of direct HttpClient injection

Repositories receive a provider that resolves the correct client on every call. This allows SSL bypass to take effect immediately without recreating Koin singletons.

JNA version pinning

dorkbox/SystemTray 4.4 performs a hardcoded version check against JNA. JetBrains Runtime 25 bundles JNA 7.x, which fails this check. Solution: resolutionStrategy.eachDependency forces JNA to 6.1.6 globally, with 5.18.1 pinned explicitly in client-ui for Windows.

AppImage manual assembly

Compose Multiplatform’s built-in Linux packaging produces DEB/RPM. AppImage is assembled manually in CI using jlink for a minimal JRE and appimagetool, with .desktop and AppStream metainfo injected.

GameCommandBuilder version configs

Each supported Minecraft version has an immutable VersionConfig — main class, tweak class, JVM flags, natives dir. NeoForge (1.21.1) requires module path separation (-p) and additional --add-opens flags for Java 21+.

Platform data directories

User data (settings, credentials, downloaded clients, skin cache, logs, crash reports) lives under a single per-OS directory, resolved by PlatformPaths in client-launcher:

OS	Path
Windows	`%LOCALAPPDATA%\Nexira\`
macOS	`~/Library/Application Support/Nexira/`
Linux	`$XDG_DATA_HOME/nexira/` (default `~/.local/share/nexira/`)

The environment variable AURA_DATA_DIR overrides the platform default on every OS — useful for moving data to another drive (e.g. D:\Nexira on Windows) without code changes.

On first launch the legacy ~/.aura/ directory (used by versions ≤ 2.2.x) is copied into the resolved data directory and a .migrated marker is written into the legacy directory. The legacy data is not deleted — users can remove it manually after verifying the migration.

Protocol constants (`AppConfig.LEGACY_*`)

The auth salt, default launcher hash, default server id and protocol JAR descriptor in AppConfig were recovered from the decompiled official SMARTYcraft launcher: Kitty-Hivens/smrt-deco. The upstream is Proguard-obfuscated (a.java, b.java, …) and archived since April 2026, so any future protocol change will need to be re-derived from a fresh dump.