Per docs/research/2026-07-30-ts4-116-oracle-plan.md §2.3-§2.4: retail's
airborne (not-yet-Contact) BSPTREE::find_collisions dispatch, when the
FOOT sphere is completely clear but the HEAD sphere hits or near-misses,
does not defer through SetCollide/Adjusted (nor the steep-poly
slide-tangent shortcut) — it records the head polygon's normal directly
and hard-stops: pc:323824-323834 (0x0053a793/0x0053a7a4), independently
cross-checked against ACE BSPTree.cs:221-230 (`SetCollisionNormal` +
`return TransitionState.Collided;`), an exact structural match confirming
this isn't a BN misdecompile. BSPQuery.cs's Path 6 `hasSphere1` branch now
does the same: `collisions.SetCollisionNormal(worldNormal1); return
TransitionState.Collided;`, replacing the old steep-shortcut-or-deferred-
SetCollide handling. This mechanically retires one of TS-4's two
`SetSlidingNormal` write sites (sphere1's) ahead of TS-4's own item.
Added two permanent diagnostics gated on the existing
PhysicsDiagnostics.ProbeIndoorBspEnabled flag (`[path-dispatch]` at
FindCollisionsCore entry, `[path5-diag]` inside Path 5) to make future
BSPQuery dispatch tracing cheaper.
HONEST RESULT of the plan's own confirming instrumentation (re-run of
DoorBugTrajectoryReplayTests.Diagnostic_Tick22760_DumpEngineInternals):
this fix does NOT change the tick-22760 outcome (harness still cn=(0,0,1)
vs live cn=(0,+1,0)). The new dispatch-entry probes show the tick-22760
mover is GROUNDED (Contact set), so it never reaches Path 6 at all — it
dispatches Path 5 -> StepSphereDown (Path 3, both DoStepDown half-steps
fail) -> EdgeSlideAfterStepDownFailed -> SpherePath.PrecipiceSlide, whose
find_crossed_edge-false fallback returns Collided with NO collision-normal
write. A fresh byte-level read of retail's SPHEREPATH::precipice_slide
(pc:274316-274326, 0x0050cc80) confirms this is byte-exact retail
behavior (`if (eax == 0) { walkable = 0; return 2; }`, no
set_collision_normal call) — not a bug. The real tick-22760 divergence is
further upstream, most likely this test's simplified door registration
(BuildEngineWithDoorFixture) not placing the door's BSP where live retail
actually intersected it, or a walkable-polygon state-capture gap — see
the research doc's Addendum 2 for the full trace and open candidates.
#116 shape-1 is therefore NARROWED, not closed: the Path-6 fix is a real,
independent retail-faithfulness improvement; the tick-22760 acceptance
criterion is not met by it and needs further harness/geometry work before
any further code change.
Full AcDream.Core.Tests suite: 4059 passed / 2 skipped, no regressions.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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