skate-3-rust-engine/docs/grind-native-assist.md

Native grind assist port status

The live game still supports the paired-truck50-50 path only. The new skate-core/src/air/trajectory/grind.rs leaves are not connected to gameplay. They must not be presented as working magnetic assistance or all-grind support.

Reference: TU3 image SHA256 f4aa113eb541bfba03dbc108cf5ab43f58c965b20fa3b82f9c40938a0ad841c4, generated PPC in the local Skate3Research/Skate3CustomEngineLayer checkout. No reference process or gameplay tests were run for this port.

Ported leaves

• 82D60C80/82D60B98: quadratic trajectory-plane intersection and later-root selection.
• 82D6A398: projected rail trajectory candidate, signed endpoint interval, radius plus GrindOffset plane, miss distance, crossing time, fixed60Hz frame, rail direction and approach direction.
• 8296EC98/82E09C80: oriented approach angle and fractional-turn fold.
• 82D6A168: height/angle ranking inside the difficulty lock distance and distance fallback outside it; removing one winner preserves retry order.
• Admission/displacement portion of82D6A840: relative height, vertical rail, perpendicular speed, ledge-side lock scalars, deck-tip allowance and maximum trajectory angle. It requires a supplied native surface result; no dummy classification or unconditional snap is provided.

These are static source translations, not a claim of verified bitwise parity. The core crate builds. The user has reserved gameplay testing for themselves.

Missing live dependencies

1. Preserve the complete indexed world-query result set for82C20728/82C20C08, then implement the rail/edge/ledge classification82C21930. The existing ground hang-up adapter only produces the fields that its ground caller reads.
2. Complete82D6A840's accepted-target publication and82D6AF58 landing-normal construction. Feed the real result through trajectory scoring/second-pass selection instead of the current WorldWithoutGrindEdges marker.
3. Connect GrindAirAdjust82D712E0 and its projection, target, and correction owners to the physical skeleton/board. The displacement leaf by itself is not the complete airborne assist.
4. Port the other contact probes/scorers and state owners. Native manager 82D875A8 uses separate centre-deck, inverted-deck, truck and tip probes. State400 boardslide,40150-50,402 tipslide,4035-0,404 backslash and405 darkslide are distinct physics states. Naming variants requires the actual chromosome producer as well as those state IDs.

Proposed read-only reference trace

Awaiting user authorization because earlier instructions prohibit launching the recomp. No synthetic gameplay input is proposed; the user would approach and land on a rail in the reference game.

Capture query inputs and indexed hit validity/fraction/position/normal/surface at82C20728 and82C20C08, the classification at82C21930, ranked candidates and accepted/rejected attempts at82D6A168/82D6A840, and GrindAirAdjust output at 82D712E0. Include state/category, mode, simulation tick, spline ID, board frame and controller inputs so these observations can be matched to their callers. Keep the trace local and do not modify the reference binaries or database.