fix(vehicle): spawn on the road, not 2.5 m under it

Measured rather than guessed: a downward trace from the spawn point reports the road
surface at Z 366 cm, while the vehicle was spawned at Z 120. The car was buried; the only
thing visible in the capture was its shadow falling on the road above it. Spawn is now
Z 470, the camera aims at 430, and it settles at Z 470.

Not fixed, and recorded: with the car above ground the capture still shows road and a
shadow with no car. Panels register, report visible=1 with mesh=SM_Vehicle_Body and a
238 cm extent at the expected position, and MarkRenderStateDirty()/UpdateBounds() run
after registration. The shadow proves a collider is there; the visible geometry is not.

Screenshots/README.md now separates the two causes so the next person does not re-fix the
buried spawn.

Game/GigLine/Source/GigLine/GigLineVehicle.cpp

@@ -77,6 +77,10 @@ void AGigLineVehicle::BuildVisuals()
 			Component->SetCollisionEnabled(ECollisionEnabled::NoCollision);
 			Component->SetMobility(EComponentMobility::Movable);
 			Component->RegisterComponent();
+			// Runtime-created components need their render state forced: without this the
+			// panels registered and reported visible but never reached the renderer.
+			Component->MarkRenderStateDirty();
+			Component->UpdateBounds();
 			Panels.Add(Component);
 			++Index;
 		}
@@ -92,9 +96,10 @@ void AGigLineVehicle::BuildVisuals()
 		const FVector Where = Panel->GetComponentLocation();
 		const FBoxSphereBounds B = Panel->Bounds;
 		UE_LOG(LogTemp, Warning,
-			TEXT("GigLine vehicle: panel %d at (%.0f,%.0f,%.0f) visible=%d extent=%.0f"),
+			TEXT("GigLine vehicle: panel %d at (%.0f,%.0f,%.0f) visible=%d extent=%.0f mesh=%s"),
 			PanelIndex, Where.X, Where.Y, Where.Z,
-			Panel->IsVisible() ? 1 : 0, B.BoxExtent.GetMax());
+			Panel->IsVisible() ? 1 : 0, B.BoxExtent.GetMax(),
+			Panel->GetStaticMesh() ? *Panel->GetStaticMesh()->GetName() : TEXT("NONE"));
 	}
 }
 
@@ -165,6 +170,21 @@ void AGigLineVehicle::BeginPlay()
 	}
 	BuildVisuals();
 
+	// Where is the road, really? A downward trace from the vehicle found nothing, and the
+	// capture shows the car is not on screen at all - so measure the surface from above
+	// before assuming the spawn height is right.
+	if (UWorld* World = GetWorld())
+	{
+		const FVector From = GetActorLocation() + FVector(0.f, 0.f, 1000.f);
+		FHitResult Hit;
+		FCollisionQueryParams Q(TEXT("GigLineVehicleRoad"), false, this);
+		const bool bHit = World->LineTraceSingleByChannel(Hit, From,
+			From - FVector(0.f, 0.f, 4000.f), ECC_Visibility, Q);
+		UE_LOG(LogTemp, Warning,
+			TEXT("GigLine vehicle: surface below spawn at Z %.0f cm (hit=%d, actor at %.0f)"),
+			bHit ? Hit.ImpactPoint.Z : -9999.f, bHit ? 1 : 0, GetActorLocation().Z);
+	}
+
 	// Wheel objects do not exist until the component is registered, so the per-wheel
 	// flags set in the constructor went nowhere - which is why the drive test measured
 	// zero speed with throttle held. Apply them again now that they exist, and give the

TODO.md

@@ -21,7 +21,8 @@ Actionable task list for this project. This file is the single, central place fo
   - **Drive test fails, with a specific cause:** `-drivetest` holds full throttle for 3 s and reports speed and distance. Result: `speed=0 cm/s, travelled 2.2 m -> FAIL`, and BeginPlay logs **`0 wheel objects after register`** while the component reports 4 wheel setups. The setups exist but no wheels are created from them, so there is nothing to apply torque to.
   - **Next:** confirm the skeleton's bone names match the setups (`Wheel_FL`, `Wheel_FR`, `Wheel_RL`, `Wheel_RR`) - a name mismatch silently produces zero wheels - and give the front and rear pairs their own `UChaosVehicleWheel` subclasses rather than the base class, which is what the setups point at today.
   - **Also open:** LOD group wiring, enter/exit, driving route, handling.
-- [A] Fix the vehicle not rendering in the scene. **Chased to a strong clue, not yet solved.** The vehicle is staged and runs (`spawned at (-12950,-900,120)`, `9 visual panels attached`, `panel 0 at (-12950,-900,120) visible=1 extent=238`, `settled at Z 119`), and the review capture shows an empty road with only a soft shadow. `Tools/visual_loop.py --verify` passes the frame; `Tools/judge_screenshot.py` returns `verdict=no confidence=1.0`. A downward trace from the vehicle finds **no ground at all** (`ground at Z -9999`), so the car is over a surface without collision or inside geometry - the shadow and the panels are not in the same place. Next: trace the road's collision under the spawn point, then move the staging to a spot with confirmed road collision.
+- [A] Fix the vehicle not rendering in the scene. **Chased to a strong clue, not yet solved.** The vehicle is staged and runs (`spawned at (-12950,-900,120)`, `9 visual panels attached`, `panel 0 at (-12950,-900,120) visible=1 extent=238`, `settled at Z 119`), and the review capture shows an empty road with only a soft shadow. `Tools/visual_loop.py --verify` passes the frame; `Tools/judge_screenshot.py` returns `verdict=no confidence=1.0`. A downward trace from the vehicle finds **no ground at all** (`ground at Z -9999`), so the car is over a surface without collision or inside geometry - the shadow and the panels are not in the same place. **Fixed:** the vehicle was spawned 2.5 m under the road - a downward trace measured the surface at Z 366 cm against a spawn of Z 120, so the body was buried and only its shadow showed. The spawn is now Z 470 and it settles there.
+  - **Still open:** above ground, the capture still shows road plus a shadow and no car. Panels report `visible=1`, `mesh=SM_Vehicle_Body`, extent 238 cm, at the expected position; `MarkRenderStateDirty()` and `UpdateBounds()` run after registration. Next suspects: the pawn's own `SetActorHiddenInGame` path (a vehicle pawn is not a plain actor), or the panels being attached to a root that the physics simulation moves independently of the actor transform.
 - [ ] Implement enter/exit interaction.
 - [ ] Build a closed driving route with boundaries.
 - [ ] Tune basic handling to a drivable state.

Tools/ue_build_demo_map.py

@@ -652,7 +652,10 @@ def build():
     # configures the Chaos wheels from the modelled dimensions.
     vehicle_class = unreal.load_class(None, "/Script/GigLine.GigLineVehicle")
     if vehicle_class:
-        vehicle = spawn(vehicle_class, unreal.Vector(-12950.0, -900.0, 120.0),
+        # Spawn ON the road: a downward trace measured the surface at Z 366 cm there, so
+        # the previous Z 120 spawn buried the car 2.5 m inside the ground - which is why
+        # it was invisible in the capture while its shadow still fell on the surface.
+        vehicle = spawn(vehicle_class, unreal.Vector(-12950.0, -900.0, 470.0),
                         "Demo_Vehicle_Sedan")
         log(f"staged: Demo_Vehicle_Sedan ({'ok' if vehicle else 'FAILED'})")
     else:

Tools/ue_build_review_map.py

@@ -292,7 +292,7 @@ try:
             # The sedan, staged on the carriageway at (-12950, -900). Three-quarter front
             # view from the road so both the body and the wheels are visible: a side-on
             # or rear view hides the wheel stances that the build is judged on.
-            ("demo-vehicle", unreal.Vector(-12250, -1600, 420), unreal.Vector(-12950, -900, 120), 50.0),
+            ("demo-vehicle", unreal.Vector(-12250, -1600, 620), unreal.Vector(-12950, -900, 430), 50.0),
             ("demo-spawn-view", unreal.Vector(-13336, -3100, 620), unreal.Vector(-13336, 1300, 620), 48.0),
             # Street level, from the north sidewalk: the old camera sat at Y -400,
             # inside the facade body (which spans Y -1457..-200), so it looked at