fix(physics): #149 — collide BSP-less landblock statics via Setup cylsphere

Town props placed as landblock stabs whose ONLY collision is a Setup
CylSphere/Sphere (no physics BSP) registered ZERO collision shapes and were
walk-through -- torches, braziers, lamp-posts, candle-stands, posts.

Root: the ISSUES #83 / A1.6 gate `!_isLandblockStab` skipped Setup
cyl/sphere registration for ALL landblock stabs, on the false assumption
"landblock stabs collide via BSP only (retail CBuildingObj)." That
over-broadened -- it also killed collision for BSP-less stabs.

Retail's CPhysicsObj::FindObjCollisions (@0x0050f050) uses binary dispatch:
the object's physics BSP if it HAS one (HAS_PHYSICS_BSP_PS 0x10000), ELSE its
CSetup CylSpheres/Spheres -- never both. Confirmed via live retail cdb on the
Holtburg torch (Setup 0x020005D8 at world (105.99,17.17)): FindObjCollisions
target num_cylsphere=1, cyl h=2.2 -- a cylsphere, exact-matching the dat
(cylSphere r=0.2 h=2.2); the StabList confirms stab[95]=0x020005D8 there.

Fix: gate the Setup cyl/sphere registration on `entityBsp == 0` instead of
stab-ness. Preserves #83's anti-doubling (stab WITH a BSP -> BSP-only) while
restoring collision for BSP-less stabs. Other landblock entities on this path
(scenery -- tree-trunk cylspheres) are unaffected.

Live-verified: torch + candle/brazier family block now; ~115 cyl/sphere
Setups register across streamed landblocks. Core suite green (1595/0).

The earlier selection-sphere hypothesis was WRONG and is reverted -- the cdb's
r=0.48 sphere was the player/NPC body (every body sphere is ~0.48), not the
torch. The correct cdb method: capture the TARGET at FindObjCollisions (not
`this` in CSphere::intersects_sphere) and confirm by position + Setup-id.

(Issue numbered #149 to stay clear of main's #148; this worktree branched
before main's #145-148 were added.)

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

docs/ISSUES.md

@@ -5482,6 +5482,28 @@ outdoors at the angle that previously erased it.
 
 # Recently closed
 
+## #149 — BSP-less landblock statics (torches/braziers/lamp-posts) were walk-through
+
+**Status:** DONE (2026-06-25, `4cf6eeb`) — town props placed as landblock stabs
+whose ONLY collision is a Setup CylSphere/Sphere (no physics BSP) had ZERO collision
+shapes registered → walk-through. Root: the ISSUES #83 / A1.6 gate `!_isLandblockStab`
+skipped Setup cyl/sphere for ALL stabs, on the false assumption *"landblock stabs
+collide via BSP only (retail CBuildingObj)."* Confirmed end-to-end via live retail
+cdb: the Holtburg torch (Setup `0x020005D8`, world (105.99,17.17)) hits
+`CPhysicsObj::FindObjCollisions` with `num_cylsphere=1`, cyl h=2.2 — a cylsphere,
+matching the dat (cylSphere r=0.2 h=2.2) exactly; the StabList confirms stab[95]=
+`0x020005D8` at that position. Fix: gate the Setup cyl/sphere registration on
+`entityBsp == 0` (retail's binary dispatch — BSP if the object has one, ELSE
+cyl/sphere; see `feedback_retail_binary_dispatch`) instead of stab-ness — preserves
+#83's anti-doubling (stab WITH a BSP → BSP-only) while restoring collision for
+BSP-less stabs. Live-verified (torch + candle/brazier family block now; ~115
+cyl/sphere Setups register across streamed landblocks). The earlier selection-sphere
+hypothesis was WRONG and reverted — the cdb's r=0.48 sphere was the player/NPC body
+(every body sphere is ~0.48), not the torch; capturing the *target* at
+`FindObjCollisions` (not `this` in `intersects_sphere`) + confirming by position +
+Setup-id is the correct cdb method. `GameWindow.cs:7281`. Core suite green (1595/0).
+(Numbered #149 to stay clear of main's #148; worktree branched before #145–148.)
+
 ## Dense-town (Arwic) FPS deep-dive — 75 → ~165 fps
 
 **Status:** DONE (2026-06-24) — `290e731` (cell-object draw batching) + `9f51a4d`

src/AcDream.App/Rendering/GameWindow.cs

@@ -3830,7 +3830,8 @@ public sealed class GameWindow : IDisposable
                 CylHeight:     (setup.Height > 0 ? setup.Height : setup.Radius * 2f) * entScale));
         }
 
-        if (shapes.Count == 0) return;
+        if (shapes.Count == 0)
+            return;
 
         // Decode PvP / Player / Impenetrable from PWD._bitfield.
         // IsCreature comes from the spawn's ItemType (server-known type).
@@ -7265,17 +7266,28 @@ public sealed class GameWindow : IDisposable
             // clobber entries via Deregister.
             {
                 var setup = _physicsDataCache.GetSetup(entity.SourceGfxObjOrSetupId);
-                // ISSUES #83 / Phase A1.6 (2026-05-21): landblock stabs use BSP
+                // Retail binary collision dispatch (CPhysicsObj::FindObjCollisions
-                // collision exclusively (retail CBuildingObj). Skip Setup-derived
+                // @0x0050f050, see feedback_retail_binary_dispatch): an object uses
-                // CylSphere/Sphere/Radius shadow registrations for stabs to
+                // its physics BSP if it HAS one (HAS_PHYSICS_BSP_PS 0x10000), ELSE
-                // prevent the same doubled-collision bug A1 fixed for the
+                // its CSetup CylSpheres/Spheres — never both. The per-part BSP loop
-                // mesh-AABB-fallback — but on the Setup path instead. Without
+                // above already registered every BSP-bearing part (entityBsp counts
-                // this gate, a stab whose source is 0x02xxxxxx (Setup) with
+                // them). So register the Setup's CylSpheres/Spheres ONLY when no BSP
-                // defined CylSpheres registers BOTH per-part BSP shadows AND a
+                // claimed this object (entityBsp == 0).
-                // CylSphere shadow with id = entity.Id, producing an invisible
+                //
-                // collision cylinder at the stab origin alongside the correct
+                // This supersedes the ISSUES #83 / A1.6 (2026-05-21) gate that
-                // BSP walls.
+                // skipped Setup cyl/sphere for ALL landblock stabs to stop a
-                if (setup is not null && !_isLandblockStab)
+                // BSP+cylinder doubled-collision. That gate over-broadened: it also
+                // killed collision for BSP-LESS stabs whose ONLY shape is a Setup
+                // CylSphere — e.g. the Holtburg town torch (stab Setup 0x020005D8,
+                // part 0x01001774 HasPhysics=False/BSP=null, cylSphere r=0.2 h=2.2).
+                // Retail collides with it via that cylsphere (live cdb 2026-06-25:
+                // FindObjCollisions target ncyl=1, cyl h=2.2 at world (105.99,17.17));
+                // acdream walked straight through. Gating on entityBsp==0 keeps #83's
+                // anti-doubling (stab WITH a BSP → BSP-only) while restoring cyl
+                // collision for BSP-less stabs. Other landblock entities on this path
+                // (scenery — tree-trunk cylspheres etc.) are unaffected: with no BSP
+                // they still register cyl/sphere exactly as before.
+                if (setup is not null && entityBsp == 0)
                 {
                     float entScale = entity.Scale > 0f ? entity.Scale : 1f;
                     uint shapeIndex = 0;