Sodium Extra is a client-side Minecraft mod that extends the Sodium performance mod with additional graphical options, visual bug fixes, and performance tweaks. Architecturally, it is a mixin-heavy mod built with the Architectury multi-platform toolchain, supporting both Fabric and NeoForge loaders. It injects into Minecraft's rendering, fog, particle, GUI, and entity systems via over 50 mixin classes, controlled by a custom mixin configuration system (CaffeineConfig). Key entry points include `SodiumExtraClientMod` (initialization, config registration, debug HUD), `SodiumExtraMixinConfigPlugin` (runtime mixin filtering based on user options), and platform-specific initializers (`SodiumExtraFabricClientModInitializer`, `SodiumExtraNeoForgeClientMod`). External dependencies are Sodium (required), Minecraft, and optionally ModMenu and Greenlight (for server-authorised fog). The mod is best described as 'OptiFine's eye-candy options for Sodium', providing fine-grained toggles for animations, particles, fog, sky/clouds, biome colors, toasts, overlays, and many performance-related features. It is not a data or research project.