Classification confidence and generalization. A diverging bar chart showing the SVM classification probability for each burst. Bars extending to the right (blue) indicate high confidence for a merger origin, while bars to the left (red) indicate a collapsar origin. Hatched bars represent the 10 independent validation samples not included in the primary training set, demonstrating the model’s robust generalization to historic events (e.g., GRB 050709) and extreme populations (e.g., GRB 221009A).