Patch release. Upgrade before recording anything else with a Virtual Hand, and before running migrate_vhi_sessions over a sessions folder. Fixed Session.save_meta now stamps pose_convention into meta.json. Without it, a session recorded by 2.5.0 was indistinguishable from a pre-2.5 one — migrate_vhi_sessions reads an absent key as legacy — so running the migration over a sessions folder negated the correct recordings into the old convention. The damage was silent and looked exactly like a hand driven backwards, and because the conversion is self-inverse there was no way to tell from the file which parity it was on. myogestic.tools.migrate_vhi_sessions imports POSE_CONVENTION from myogestic.session instead of defining its own copy, so a migrated session and a freshly recorded one cannot drift into disagreeing about what convention they are in. If you recorded with 2.5.0 Those sessions carry no stamp and are already in the standard convention. Do not run the migration on them — it would negate correct data. Either re-pack them under 2.5.1, or add "pose_convention": "standard" to their meta.json by hand. Compatibility Unchanged from 2.5.0: still requires Virtual Hand Interface 2.0 (vocabulary_version 2). No API changes. Full changelog: https://github.com/NsquaredLab/MyoGestic/compare/v2.5.0...v2.5.1