diff --git a/crates/skate-core/src/physics/grind_contact.rs b/crates/skate-core/src/physics/grind_contact.rs
new file mode 100644
index 00000000..854d0f1b
--- /dev/null
+++ b/crates/skate-core/src/physics/grind_contact.rs
@@ -0,0 +1,33 @@
+//! Native grind contact leaf82C1E2C8. This is distinct from the tolerant wheel
+//! triangle query: exact parallel rejection and closed segment/barycentric bounds.
+use super::native_arithmetic::dot3;
+type V = [f32; 4];
+
+/// Intersect a grind primitive segment with a board/truck probe triangle.
+/// Returns the native hit position; acquisition/scoring belongs to the caller.
+/// Both windings are accepted. Failed branches do not synthesize a contact.
+pub fn segment_triangle(start: V, end: V, triangle: [V; 3]) -> Option<V> {
+    let [a, b, c] = triangle;
+    let ac = sub(c, a);
+    let ab = sub(b, a);
+    let direction = sub(end, start);
+    let normal = cross(ab, ac);
+    let denominator = -dot3(direction, normal);
+    if denominator == 0.0 { return None; }
+    let from = sub(start, a);
+    let inverse = 1.0 / denominator;
+    let t = inverse * dot3(from, normal);
+    if t < 0.0 || t > 1.0 { return None; }
+    let side = cross(from, direction);
+    let u = inverse * dot3(ac, side);
+    let v = (1.0 / -denominator) * dot3(ab, side);
+    if u + v > 1.0 || u < 0.0 || v < 0.0 { return None; }
+    Some(core::array::from_fn(|i| direction[i].mul_add(t, start[i])))
+}
+
+fn sub(a: V, b: V) -> V { core::array::from_fn(|i| a[i] - b[i]) }
+fn cross(a: V, b: V) -> V {
+    [(-a[2]).mul_add(b[1], a[1] * b[2]),
+     (-a[0]).mul_add(b[2], a[2] * b[0]),
+     (-a[1]).mul_add(b[0], a[0] * b[1]), 0.0]
+}
diff --git a/crates/skate-core/src/physics/mod.rs b/crates/skate-core/src/physics/mod.rs
index 10c4c9ab..4daaf636 100644
--- a/crates/skate-core/src/physics/mod.rs
+++ b/crates/skate-core/src/physics/mod.rs
@@ -40,6 +40,7 @@ pub mod solver;
 pub mod startup;
 mod triangle_closest;
 pub mod triangle_query;
+pub mod grind_contact;
 mod triangle_sweep;
 mod triangle_sweep_roots;
 mod triangle_sweep_walk;
diff --git a/docs/GRIND_INTEGRATION.md b/docs/GRIND_INTEGRATION.md
index 909b35e6..5bbb01bf 100644
--- a/docs/GRIND_INTEGRATION.md
+++ b/docs/GRIND_INTEGRATION.md
@@ -37,6 +37,10 @@ its truncated pseudocode is not sufficient to port the nonempty branches.
   queries (`82C1FDC0`, `82C20130`, `82C1FB98`, `82C1F968`) before scoring. For
   example `82D89150` handles a two-truck candidate; it is not a nearest-rail
   angle classifier. Selection output has candidate byte384 in a416-byte record.
+- `82C1E2C8` is now ported in core `physics/grind_contact.rs`: the exact
+  segment/triangle leaf used by those truck/deck queries. It retains the
+  zero-denominator rejection and closed0..1 bounds, unlike wheel probes with
+  their endpoint tolerance. It does not itself accept a grind.
 - `82D8AB08`: post-input manager publication precedes state selection.
 - Native selector maps actual candidate grind type0..5 to states401,400,402,
   403,404,405. `player_state/selection.rs` currently publishes no candidate.