AI disclosure: This mod's code and description was written by an AI assistant (Claude), based on a problem I ran into and described. I tested it against my own broken blueprints before publishing, but I did not hand-write the Lua myself. If that matters to you, now you know.

What this fixes

Factorio 2.1.7 renamed two recipe prototypes:

molten-iron → iron-ore-melting
molten-copper → copper-ore-melting

Any blueprint made before that rename which references the old recipe name (constant combinators, circuit-set-recipe on a foundry, parametrised blueprints) removes the affected entity from the blueprint on import.

This mod adds the old names back as hidden aliases of the current recipes, so those entities resolve again on import.

What it does
Registers molten-iron and molten-copper as hidden recipes, cloned from iron-ore-melting and copper-ore-melting
Enabled by default, no technology needed
Doesn't touch anything else - no balance changes, no new items
What it doesn't do
It won't fix blueprints that already had the entity stripped out before you installed this mod - only blueprints imported after enabling it
It's not a substitute for updating your blueprints properly if you maintain a library

Feedback

I'm not an experienced Factorio modder, this was a quick fix for my own broken blueprints that I'm sharing in case it helps someone else. If it breaks something or you find an edge case it doesn't handle, open an issue or leave a comment. As this was a quick fix i probably won't look at it regularly (or at all) but atleast others'll know the bug