Publish native grind balance and board adjustment intents

docs/grind-stick-controls.md

@@ -0,0 +1,40 @@
+# Grind stick publication
+
+The controller listener omitted the four grind intents consumed by the imported
+ActionGraph and MotionGraph. Neutral defaults therefore reached the existing
+grind twist, translation, stability and nose/tail physics controls regardless of
+stick movement.
+
+`input::grind_intentions::produce` now translates the TU3 listener emissions from
+`Fill825999F0`:
+
+| Intent | Derived controller value | Native emission region |
+| --- | --- | --- |
+| GrindBalanceX | minus left X | 8259ACF0..8259AD0C |
+| PhysGrindTranslation | clamp(left X + right X, -1, 1) | 8259AD40..8259AD5C |
+| PhysGrindStabilityNudge | left X | 8259AD5C..8259AD78 |
+| PhysGrindUpDown | right Y | 8259AD78..8259AD94 |
+
+Derived input words 7, 9 and 10 carry those axes. The listener saves right Y at
+stack offset 88 before reloading it into f21 for publication. Neither an extra
+dead zone nor a grinding-state gate is added here; the native listener emits
+these records whenever their individual value is nonzero. The action-intent map
+is rebuilt each tick, so releasing a stick removes its record.
+
+The stock ActionGraph forwards the physics intents to the MotionGraph and applies
+its own mirror filter to GrindBalanceX in the grinding state. The MotionGraph
+attaches the physics attributes and feeds GrindControlFade. Existing consumers
+include boardslide translation, tip-slide stability nudge, and the 82D89F58 truck
+control feeding 82D40290 deck orientation. Nose/tail response depends on the grind
+family and current contact, rather than applying an unrestricted rotation to all
+grinds. No physical tuning changes are part of this patch.
+
+Evidence: generated PPC from Skate3CustomEngineLayer and the imported stock graph
+assets. Executable image `default_82000000_011B0000.bin`, base 82000000, SHA256
+`f4aa113eb541bfba03dbc108cf5ab43f58c965b20fa3b82f9c40938a0ad841c4`.
+The sum clamp constants at 8231A844 and 8216DEE0 are +1 and -1. Existing truck
+orientation constants at 822F91E4 and 8208ECD8 were checked as -0.68 and +0.68.
+
+Validation is compilation and source tracing only. In-game feel, transitions and
+stance combinations remain for the user's visual testing; this change does not
+establish complete behavioral parity of the surrounding grind implementation.