Spine 3899 Updated

Run the embedded JsonRollback tool via your command line, ensuring you specify your target rollback version as 3.8.99 .

When Esoteric Software rolled out Spine 4.0 and subsequent iterations (such as 4.1, 4.2, and 4.3), they fundamentally rewrote the architecture. Graph editors replaced linear curves, and curves were shifted from timeline keys directly onto the data structures. This means keeping 3.8.99 updated or properly converting its files is a non-trivial milestone for long-term project pipelines. The Local Asset Dilemma spine 3899 updated