Failure when syncing recipes with Forgified Fabric API and certain other mods installed

[unilock]

Minecraft version

26.1.x

Describe the bug

Recipes from certain mods fail to sync when a mod requests it and Forgified Fabric API is installed, due to "multiple entries with same key" when creating the client-side RecipeMap

Steps to reproduce

1. Install Minecraft, NeoForge, Sinytra Connector, Launchpad, and Forgified Fabric API
2. Install a mod that requires recipes to be synced, such as Reliable Recipe Viewer
3. Install a mod that triggers this issue, such as Alloyed
4. Start the game and create a new world
5. Observe in the logs that the recipe sync packet failed to handle on the client
6. Observe in the recipe viewer that only tags can be viewed when attempting to view recipes for any item (meaning there is no recipe data available)

Logs

https://gist.github.com/unilock/2111c945174a44833cbbf60c1b9fd9de

Additional context

Also occurs with Tech Reborn recipes, and most likely those from other mods that I haven't tested

[Su5eD]

I think this is a bug with RRV. It request recipe synchronization for addons from both Fabric and NeoForge when Launchpad and FFAPI are installed, then listens to both sides' receiver events. Naturally, this will result in duplicate recipes being put in the recipe map when it tries to combine reecived results from both Fabric and NeoForge into one map.

https://github.com/cassiancc/ReliableRecipeViewer/blob/f01d80ee7711d9950e32c9dac4618566bcd66bc1/src/main/java/cc/cassian/rrv/common/recipe/ServerRecipeManager.java#L62-L69

Listening to the fabric sync event itself is fine because Fabric mods will only sync their recipes through that event, but mods with RRV integration will call synchronizeRecipeType and have sync registered to both APIs, which leads to the error. I've tested this with Tech Reborn, which does not have an RRV integration, its recipes are synced only through Fabric and it worked fine. So I think the solution is to simply not call FabricUtil.synchronizeRecipeType on NeoForge.

Furthermore I think on our side there's a different issue, that being the fact ClientRecipeSynchronizedEvent doesn't give access to recipes synced by NeoForge, so mods that rely only on this event would not be able to read all available recipes. I'll try to bridge the APIs so that Fabric recipes are available on NeoForge and vice versa. That way, RRV will only need to listen to the Neo sync event.

[Su5eD]

Closing as this is fixed on our side now. Opened a PR in RRV for fixing this on their side as well:

• Fix duplicate recipes received during synchronization on NeoForge cassiancc/ReliableRecipeViewer#59