Classic vs Slim arms
Four-pixel and three-pixel arms need different UV layouts.
Verification status: reference checklist. No claim of completed game-client import tests.
Classic arms are four logical pixels wide. Slim arms are three. Both use a 64×64 texture, but arm-face positions and widths differ. Metadata and your chosen client model should agree.
Use the converter to resample arm faces while retaining non-arm pixels. A narrower arm loses some detail. Inspect front, back, inner side, outer side, top and bottom after conversion. The file checker verifies pixels; in-game validation remains a separate step.