skate-3-rust-engine/docs/wheel-contact-drag-binding.md

Wheel contact drag binding

The user capture logs/game-20260907-230543.stderr.log begins with normal four-wheel riding. Later neutral-input samples have zero turn, brake, balance, and slide, with truck targets decaying to zero. Samples 4320–5160 repeatedly report three wheel contacts. This rules out persistent controller steering in that interval; it does not establish which contact or force caused the symptom.

Static inspection found an independent, definite adapter mismatch:

• TU3 Skateboard::UpdatePostPhysics (82C07D20), at 82C08634, stores the per-wheel contact-dependent drag at inertia offset 36.
• RigidBody::DynamicUpdate (82AE6590) reads offset 36 for angular damping and offset 32 for linear damping. The Rust inertia adapter likewise packs linear_drag at word 8 and angular_drag at word 9.
• The game previously assigned the wheel result to linear_drag. It now assigns angular_drag, and the retained field is named accordingly.

Values, contact gates, update order, and reset lifetime are unchanged. The original constant ground torque was also inspected and is retained.

Evidence image: Skate3Research/research/reverse-engineering/XexDump/default_82000000_011B0000.bin, base 82000000, SHA-256 f4aa113eb541bfba03dbc108cf5ab43f58c965b20fa3b82f9c40938a0ad841c4. Instruction extractions: logs/biped-82C07D20.txt and logs/biped-82AE6590.txt; generated reference source is in the research project's Skate3CustomEngineLayer/generated directory.

Validation: compile only; gameplay confirmation remains with the user. Optional skate_game::riding_trace=debug logging now includes board body states, contact reports, and queued forces to distinguish remaining physical faults if the correction does not resolve the complete symptom.