v2_a M3/M4 alignment variant
M1/M2 rows in the comparison files are fixed references recomputed on the original grouped folds. Only M3/M4 training losses changed. See training_history.csv for per-epoch loss components and row-collapse scores. retrieval_metrics_learned_only.csv restricts candidates to the same clip. reconstruction_metrics_learned_only.csv contrasts aligned and shuffled non-target streams. The experiment does not include RoPE, Gaussian bias, or latent-length changes.