KB: #124 close-out -- triangle pick + the authored one-hull-segment zone rule

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

context/combat-damage.md

@@ -102,6 +102,22 @@ the DCS = the struck SEGMENT → its `dzone` (the SKL segment→zone map, `GetSe
 `targetDamageZone`. The cylinder lottery (STEP 6) was only ever the UNAIMED path. The port's
 whole-mech box pick + "STEP-6 zone under the boresight" funnels AIMED fire through the unaimed
 lottery — which is exactly the night-6 report (#73): aim at the arm, get the spray.
+**COMPLETED 2026-08-03 (#124, the zone-walk matrix): the pick is now TRIANGLE-ACCURATE and the
+zone rule is settled against the authored skeleton [T0 data + T2 matrix].** The sphere
+approximation measurably mis-picked (aim dead-on dtorso -> picked rgun/ruleg; its own comments
+admitted a foot could be unhittable behind its own knee) — `MechSegmentPick` now runs a sphere
+PRE-FILTER then Moller-Trumbore nearest-hit over the threaded segments' posed meshes (CPU
+triangle cache from each object's own BGF buffers, `BTGetPickMesh`).  **The zone is the struck
+segment's SKL dzone, ALWAYS**: the madcat's pickable skeleton authors 18 segments — hip,
+shoulders, guns, thighs, knees, ankles+toes, and ONE hull piece (`jointshakey` -> dtorso).  No
+ltorso/rtorso/utorso/rear/door/searchlight segments exist, so aimed fire at any torso panel
+authentically designates CENTER TORSO — the side/rear/upper panels strip only via the UNAIMED
+path (missiles/splash/rams through the cylinder).  A brief shared-carrier->cylinder override was
+an embellishment and was removed same-day.  Final matrix (two-node, spinning target, servo
+walker): limbs 55/70 in-zone (legs/feet 6/6), hull-family aims -> dtorso 56/69, victim
+consumption matching.  **The night-10 field audit table is this model's fingerprint** — 'only
+LCT gets hits' from aimed energy IS the pod's design.  Bench: [[test-harness]] §zone-walk.
+
 **IMPLEMENTED (2026-07-29/30) [T2 bench]: the aimed PER-PART pick.**
 `BTL4VideoRenderer::MechSegmentPick` (btl4vid.cpp): at tree build, each segment's draw object +
 `GetPrimaryDamageZone()` (SEGMENT.h — carried per segment in the skeleton STREAM, read by