Sideload - Web UIs for Schedule I Mods

🛟 Need help or found a bug? Get support at support.doodesch.de/sideload.

A framework, not a feature. Sideload renders mod interfaces written as index.html + app.css + app.js into real Unity UI and TextMeshPro. No browser, no native code, no subprocess. Install it because a mod you want depends on it.

Source + docs · Reference app (WhatsDab) · Support

Players

Sideload adds no gameplay, no menu and no phone app of its own. Mods that build their interface with it list it as a dependency and your mod manager installs it for you. It sits idle until one of those mods registers an app, and every developer tool inside it is off until you switch it on.

Installed by hand? Sideload.dll goes in Mods/, and AngleSharp.dll + Jint.dll + Esprima.dll go in UserLibs/ (the mod also finds them next to itself in Mods/). Without them no page will build.

Mod authors

• HTML instead of nested panels, CSS instead of sizeDelta arithmetic. Real flexbox, a real cascade, real selectors, TextMeshPro text.
• One call for a phone app. Apps.Register(id, bundlePrefix, title) and your bundle renders behind an icon on the in game phone. Registering before Sideload loads is fine; the call replays.
• A two way bridge. s1.call('name', arg) reaches a C# handler in the same frame and returns its string; app.Emit('name', payload) pushes back into s1.on(...).
• Chrome DevTools. One preference and the real inspector attaches to a page running inside the game: console, evaluate, Elements tree, reload from disk.
• No hard dependency. The Sideload.Api shim is one file with zero references. It is a no op when Sideload is absent and lights up when it is there, so your mod ships one DLL either way.
• fetch is default deny. A page reaches no host until your mod names it with AllowHost.

Start here: WhatsDab is a complete chat app for the in game phone, written as three web files, that you can install, read and copy. The step by step guide, the exact CSS subset and the layout rules that differ from a browser are in the wiki.

Requirements

Schedule I (IL2CPP) with MelonLoader 0.7.3+. No S1API.

Settings

Under Sideload_01_Main in UserData/MelonPreferences.cfg. All of it is developer tooling and all of it is off by default.

DevTools (false) turns on the Chrome DevTools Protocol server on 127.0.0.1; anything that can reach that port can run code in your pages, so leave it off unless you are building an app. DevToolsPort (9333) is the loopback port. DevToolsAutoOpen (true) opens the browser at the landing page once the first page mounts. DevToolsFetchFrontend (true) lets Sideload download the DevTools interface once into UserData/, so the inspector works offline afterwards. DevToolsFrontend (empty) overrides that with a folder holding your own copy.

License

MIT. See the included LICENSE.md. Bundles AngleSharp (MIT) and Jint with Esprima (BSD-2).