Celeritas Compatibility Bridge

A drop-in stand-in for the legacy Celeritas mod, bundled with Actinium so old addons keep working.

This is a tiny companion mod that ships with Actinium. It plays the part of the old Celeritas mod, so mods that were made for Celeritas (addons, dependencies, config mods — anything that checks "is Celeritas installed?") still see it as present and keep working normally.

Why do you need it?

Celeritas was merged into Actinium a while ago, and its old mod id no longer exists on its own. Some mods still expect it:

• mods with a hard dependency on Celeritas (required-after:celeritas) would refuse to load;
• mods that hook into Celeritas' classes would crash or behave strangely.

The bridge makes those mods believe Celeritas is right where they left it — while in the background everything is actually handled by Actinium.

How to use it

1. Install Actinium as usual.
2. Put celeritas-compat-bridge-<version>.jar into your mods/ folder next to it.
3. Done. You don't need to configure anything — it just sits there quietly.

If your modpack doesn't include any Celeritas addons, the bridge is harmless to skip (it does nothing on its own), but there's no downside to having it installed either.

Notes

• The bridge requires Actinium to be installed and loads after it, so the two always work together — don't install it without Actinium.
• It mirrors the Celeritas 2.4.0-era API for compatibility. If an addon needs something newer, it should be updated to target Actinium directly instead.
• For modpack players this is a "drop it in and forget it" mod — no config, no UI.