Apollo

Decoder-only Transformer (RoPE, RMSNorm, SwiGLU, tied embeddings) that generates monophonic melodies as symbolic tokens (BAR / POS / PITCH / DUR) conditioned on a header (tempo, time signature, key, bars, density, register, ...).

model.safetensors: fp16 weights. lm_head is tied to emb.weight, so head.weight is not stored; build the model, load with strict=False, and the tie fills it.
config.json: architecture (cfg), context length, training step and validation loss.
vocab.json: token list in id order.
best/ and last/: training checkpoints (.pt), used for resuming; load only from sources you trust.

Trained on melodies extracted from the Lakh MIDI dataset. Check the licensing of the source data before any commercial use.