MP: world structures (garages/walls) TARGETABLE -- boresight ray-tests the static collision tree (task #50)

The boresight's non-mech pick only sampled the VISUAL heightfield (BTGroundRayHit),
which on arena1 is a single flat 'sky'-named ground mesh (and class-42 BuildTables
likewise holds only 'sky') -- so shots passed THROUGH the garages/walls and only mechs
moved the HUD range axis (user-reported regression: "buildings used to move the range
axis; now only mechs do, and you can only fire at a peer").

Real fix: the boresight now ALSO ray-tests the ZONE'S STATIC COLLISION SOLID TREE --
the same geometry that already blocks the mech's walk. Authentic engine mechanism:
Mover::FindBoxedSolidHitBy already tests the static world via
zone->GetCollisionRoot()->FindBoundingBoxHitBy(line). Factored its "static world" tail
into Mover::FindStaticSolidHitBy(Line*) (static solids only, no movers), wrapped by
Mech::WorldStructurePick(start,dir,range,&hit) (builds the world-space Line, reads the
entry point back via line->FindEnd since HitByBounded clips line->length=enter).

Boresight pick order is now: closest MECH (PickRayHit, damage zones + lock) -> closest
STRUCTURE (WorldStructurePick; occludes a mech BEHIND it; designates the gBTTerrainEntity
sentinel + entry point, so the range caret reads the structure distance and NO lock ring
draws, mech4.cpp:4529) -> flat ground (BTGroundRayHit) -> sky (fire-at-nothing). Also
un-skips arena1's misnamed-'sky' flat ground so the ground tier works (btvisgnd
geometry-aware skip + [mapent]/[rendent] census).

Verified headless: a BT_WSWEEP horizontal ray-fan on arena1 tracks position (3/24 hits
near the boundary -> 17-21/24 inside the interior garage cluster -> 3/24 past it =
DISCRETE interior solids, not an enclosing box), no crash/assert/AV. Interactive aim
(BTGetAimRay) can't run headless (no window -> noRay), so the sweep is the headless proof;
interactive aim is user-verified.

Note: FindBoundingBoxUnder (the ground/containedByNode BoundingBoxTree) is DOWNWARD-only
(gravity/ground-snap: *height = FindDistanceBelowBounded), useless for a horizontal
boresight; the static SOLID tree's FindBoundingBoxHitBy is the only ray-vs-world query.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

context/combat-damage.md

@@ -104,6 +104,32 @@ bug was fixed en route: every
 renderable rebuild stomped `mCamera` back to the chase eye (btl4vid `mViewInside` now persists
 the chosen view — the aim camera feed and the V toggle both depend on it).
 
+**WORLD STRUCTURES ARE TARGETABLE via the STATIC COLLISION TREE (task #50, 2026-07-15) [T2].**
+The `BTGroundRayHit` "terrain" tier only samples the VISUAL heightfield, which on arena1 is a
+single flat `'sky'`-named ground mesh (`[visgnd] sampler ready: 1 terrain instances`) — and the
+class-42 map-instance stream (`BuildTables`) likewise holds only `'sky'`. So the garages/walls
+were invisible to the pick → shots passed through them, and only mechs moved the range axis (the
+user-reported regression). The FIX: the boresight now also ray-tests the **zone's static collision
+solid tree** — the SAME geometry that blocks the mech's walk. Mechanism is authentic engine code:
+`Mover::FindBoxedSolidHitBy` (MOVER.cpp) already tests movers, doors, AND the static world
+(`application->GetInterestManager()->GetInterestZone(interestZoneID)->GetCollisionRoot()->FindBoundingBoxHitBy(line)`).
+We factored its "test against the static world" tail into **`Mover::FindStaticSolidHitBy(Line*)`**
+(static solids only, no movers), wrapped by **`Mech::WorldStructurePick(start,dir,range,&hit)`**
+(mech.cpp — builds the world-space `Line`, reads the entry point back via `line->FindEnd` since
+`FindBoundingBoxHitBy`→`HitByBounded` clips `line->length = enter`). The pick order in mech4.cpp is
+now: closest MECH (`PickRayHit`, damage zones + lock) → closest STRUCTURE (`WorldStructurePick`,
+occludes a mech BEHIND it) → flat ground (`BTGroundRayHit`) → sky (fire-at-nothing). A structure
+hit designates `mech+0x388 = gBTTerrainEntity` (the no-damage-zone sentinel) + `0x37c` = the entry
+point, so the range caret reads the structure distance and NO lock ring draws (mech4.cpp:4529, the
+`des != hotTarget` branch), exactly the reported authentic behavior. ⚠ There is NO ray query
+against the ground/`containedByNode` `BoundingBoxTree` — `FindBoundingBoxUnder` is DOWNWARD-only
+(gravity/ground-snap: `*height = FindDistanceBelowBounded`), useless for a horizontal boresight;
+the static SOLID tree (`BoxedSolidTree::FindBoundingBoxHitBy`) is the only ray-vs-world query.
+Verified: a `BT_WSWEEP` horizontal ray-fan on arena1 tracks position (3/24 hits near the boundary
+→ 17-21/24 inside the interior garage cluster → 3/24 past it — discrete interior solids, not just
+an enclosing box), no crash. The interactive boresight (`BTGetAimRay`) can't be exercised headless
+(no window → `noRay`), so the SWEEP is the headless proof; interactive aim is user-verified.
+
 ## Firing arc + muzzles
 There is NO firing-arc field in the binary (`Emitter::FireWeapon` fires whenever HasActiveTarget) —
 the 1995 game got away with it because it was **cockpit-only** (a beam behind you is off-camera). The

context/open-questions.md

@@ -154,6 +154,17 @@ register.  ⚠ The audit also flags the damage-economy item as SELF-CONTRADICTOR
   centred); (c) pre-burial, the pick still
   tests the sinking wreck's collision box at its parked position (pre-existing wreck-targeting
   behavior).
+- **✅ WORLD STRUCTURES (garages/walls) now targetable (task #50, 2026-07-15)** — the world-pick's
+  non-mech tier previously only sampled the visual heightfield (`BTGroundRayHit`), which on arena1
+  is a single flat `'sky'` ground mesh → shots passed THROUGH the garages and only mechs moved the
+  range axis (user-reported regression). Resolved by ray-testing the **zone's static collision
+  solid tree** (the geometry that already blocks the walk) via the authentic engine query
+  `Mover::FindBoxedSolidHitBy`'s static-world tail — factored into `Mover::FindStaticSolidHitBy` +
+  `Mech::WorldStructurePick`. See [[combat-damage]] "WORLD STRUCTURES ARE TARGETABLE". This also
+  closes the old "0x388 writer is un-exported / unknown world-pick mechanism" residue: the
+  authentic non-mech world pick is the static-solid-tree ray query (`BoxedSolidTree::FindBoundingBoxHitBy`),
+  the same one `FindBoxedSolidHitBy` uses for mover-vs-world collision. Interactive aim is
+  user-verified (headless has no `BTGetAimRay`); the `BT_WSWEEP` ray-fan is the headless proof.
 - **Cockpit HUD leftovers (tasks #35-#38 residue, 2026-07-08)** — the reticle + 7 weapon pips +
   ALL the instrument dynamics are LIVE (the Execute @004cdcf0 gap was RECOVERED via capstone
   disasm, task #37; the authentic Lock producer + the simple-X mode landed in #38 — see