Is the IDE a primary input for building the program? Is the IDE a build dependency? Probably not. Certainly not based on the situation you described.

The LLM equivalent here would be programmatically generating synthetic input or cleaning input for training. You don't need the tools used to generate or clean the data in order to train the model, and thus they can be propriety in the context of an open source model, so long as the source for the model is open (the training data).