Connect native stalled grind release phase and outward exit forces

docs/grind-release.md

@@ -0,0 +1,31 @@
+# Grind release at low speed and rail ends
+
+TU3 reference: default_82000000_011B0000.bin, base82000000,
+SHA256 f4aa113eb541bfba03dbc108cf5ab43f58c965b20fa3b82f9c40938a0ad841c4.
+Static generated instruction extracts are under logs/biped-<address>.txt.
+
+Observed: PreUpdate82D3F4E8 owns a latched leaving phase. Decision82D40DA0
+enters it after more than60 state updates when Processed2652 speed is below
+0.15m/s, or on the family exit condition. It dispatches exit forces instead
+of the ordinary holding-force update. More than35 leaving updates requests
+native reason17. The previous host never ran this phase and continued pinning
+and orienting the board while stationary.
+
+Connected Release state and the existing physical body/force/request owners.
+50-50 exit82D41DF0 uses100 side/125 lift below investigation kind2, otherwise
+10 side/0 lift, capped by outward speed1.0. Helper82D3F850 uses the actual
+contact side and support normal. Other static-rail families use their native
+exit calls82D428C0/82D420A0/82D42A80/82D41250. Ordinary friction/pinning and
+orientation updates do not run during release. GRIND_RELEASE records the
+transition during user gameplay.
+
+Endpoint queries already clip segment intersections to[0,1]; losing the last
+contact makes the existing selector enter Nonspecific701 and disable the
+hook, then choose airborne/ground from actual contacts. No infinite extension
+or endpoint teleport was added. The release phase addresses a board that
+stalls while its last truck/tip remains supported at an endpoint.
+
+Scope: common slow-speed/explicit release and static-rail exit forces.
+Specialized tipslide drop-in and investigation-driven early-exit branches
+remain separate existing gaps; this does not claim full retail parity.
+Build only, no tests or automated gameplay. Visual checking is left to user.