fix(physics): S2 — static publication emits authored Spheres as Spheres (AP-155 narrowed)

Both static sites (LandblockPhysicsPublisher, the headless-only
LandblockPhysicsContentBuilder) emitted an authored Setup Sphere as a
base-anchored Cylinder of radius r and height 2r. The live path emits a
Sphere for the same data, so the same object collided differently by
arrival route, and the narrow phase met a flat cap where retail meets a
curved surface. Both sites now mirror ShadowShapeBuilder.FromSetup's
Sphere block exactly.

Combined Opus review: PASS. Its numeric verification of the dispatch
test's geometry (head-sphere clearance 0.201 m for the true sphere; the
cylinder counterfactual inside by 0.10 m XY with the Z band overlapping)
is what makes the discrimination claim more than a sabotage anecdote,
and its F8 finding is applied: the test now carries a POSITIVE control —
aiming straight through the boulder's centre must block — so a
membership/seed regression can no longer masquerade as a curve-hit
pass. F4 applied: CylHeight is asserted, not inferred (the C4 lesson).
F3 applied: the deleted Quaternion.Inverse base composition is recorded
as internally coherent for the old cylinder's world-Z axis — the defect
was the shape TYPE, not that rotation math.

The review also verified the deleted-cylinder blast radius: the F2
overlay's drawn span is IDENTICAL for both shapes (old [c-r, c+r], new
[c-r, c+r]); the flood sphere's centre rises by exactly r, which cannot
change outdoor membership (XY rectangle) and lands the indoor half on
Session B's dungeon gate alongside S1B; and the sphere-branch flood is
now pinned uncapped by a genuine eleventh-shape A/B test.
PublishStaticCollision — the headless static path — gains its first
test ever.

AP-155 is NARROWED, not deleted (review F13): the has-BSP source split
(entity.MeshRefs vs setup.Parts + AnimPartChanged) survives and keeps
the row active. The shared-primitive-emitter refactor that would make
route independence a compile-time property is the filed follow-up
(review F20).

Population: 3,506 of 5,935 installed Setups, structurally equal to
AP-157's third-branch count (byte-identical classifier — three
independent routes agree: 3,605 - 99 = 3,506).

Clean-room suite at implementation: 11,253 passed / 6 skipped / 0
failed on landed S1B. Post-review-hardening: Publisher tests 25/25,
Content tests 2/2, both green.

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

src/AcDream.App/Streaming/LandblockPhysicsPublisher.cs

@@ -1011,6 +1011,16 @@ public sealed class LandblockPhysicsPublisher
 
             if (setup.Cylinders.Length == 0)
             {
+                // AP-155: mirror ShadowShapeBuilder.FromSetup's step-2 Sphere
+                // emission EXACTLY (same origin/scale composition, same
+                // Radius<=0 guard) — a true Sphere, not a height-capped
+                // Cylinder. Retail's CPhysicsObj::FindObjCollisions dispatches
+                // an authored Setup Sphere to CSphere::intersects_sphere;
+                // there is no cylinder substitution for this branch. Emitting
+                // Cylinder here (base = origin - r*ẑ, height = 2r) made a
+                // static object's narrow phase disagree with the SAME object
+                // arriving as a live spawn via FromSetup — the route-
+                // dependence this fix closes.
                 for (int sphereIndex = 0;
                     sphereIndex < setup.Spheres.Length;
                     sphereIndex++)
@@ -1022,17 +1032,15 @@ public sealed class LandblockPhysicsPublisher
 
                     float radius = sphere.Radius * scale;
                     Vector3 localOffset = sphere.Origin * scale;
-                    Vector3 localBaseOffset = localOffset
-                        + Vector3.Transform(
-                            -Vector3.UnitZ * radius,
-                            Quaternion.Inverse(entity.Rotation));
-                    setupShapes.Add(ShadowShape.Cylinder(
+                    setupShapes.Add(// (Review F3: the deleted Quaternion.Inverse base composition was
+                    // internally coherent for the old CYLINDER's world-Z axis — the
+                    // defect was the shape TYPE, not that rotation math.)
+                    ShadowShape.Sphere(
                         gfxObjId: entity.SourceGfxObjOrSetupId,
-                        localPosition: localBaseOffset,
+                        localPosition: localOffset,
                         localRotation: Quaternion.Identity,
                         scale: scale,
-                        radius: radius,
-                        cylHeight: radius * 2f));
+                        radius: radius));
                 }
             }
 
@@ -1080,8 +1088,11 @@ public sealed class LandblockPhysicsPublisher
 
         for (int index = 0; index < shapes.Count; index++)
         {
+            // AP-155: the Setup-derived shape can now be Cylinder OR Sphere
+            // (never both — see ShadowShapeBuilder.FromSetup step 1/2). Read
+            // the actual emitted type rather than assuming Cylinder.
             Console.WriteLine(FormattableString.Invariant(
-                $"[entity-source] id=0x{entity.Id:X8} entityId=0x{entity.Id:X8} src=0x{entity.SourceGfxObjOrSetupId:X8} gfxObj=0x{shapes[index].GfxObjId:X8} lb=0x{landblock.LandblockId:X8} type=Cylinder note=setup-part{index} state=0x{0u:X8} flags={EntityCollisionFlags.None}"));
+                $"[entity-source] id=0x{entity.Id:X8} entityId=0x{entity.Id:X8} src=0x{entity.SourceGfxObjOrSetupId:X8} gfxObj=0x{shapes[index].GfxObjId:X8} lb=0x{landblock.LandblockId:X8} type={shapes[index].CollisionType} note=setup-part{index} state=0x{0u:X8} flags={EntityCollisionFlags.None}"));
         }
     }
 

src/AcDream.Content/LandblockPhysicsContentBuilder.cs

@@ -666,6 +666,11 @@ public static class LandblockPhysicsContentBuilder
 
             if (setup.Cylinders.Length == 0)
             {
+                // AP-155: mirror ShadowShapeBuilder.FromSetup's step-2 Sphere
+                // emission EXACTLY (same origin/scale composition, same
+                // Radius<=0 guard) — a true Sphere, not a height-capped
+                // Cylinder. See LandblockPhysicsPublisher's identical fix for
+                // the full retail-anchor note.
                 for (int index = 0;
                     index < setup.Spheres.Length;
                     index++)
@@ -675,17 +680,15 @@ public static class LandblockPhysicsContentBuilder
                         continue;
                     float radius = sphere.Radius * scale;
                     Vector3 localOffset = sphere.Origin * scale;
-                    Vector3 localBaseOffset = localOffset
-                        + Vector3.Transform(
-                            -Vector3.UnitZ * radius,
-                            Quaternion.Inverse(entity.Rotation));
-                    setupShapes.Add(ShadowShape.Cylinder(
+                    setupShapes.Add(// (Review F3: the deleted Quaternion.Inverse base composition was
+                    // internally coherent for the old CYLINDER's world-Z axis — the
+                    // defect was the shape TYPE, not that rotation math.)
+                    ShadowShape.Sphere(
                         entity.SourceGfxObjOrSetupId,
-                        localBaseOffset,
+                        localOffset,
                         Quaternion.Identity,
                         scale,
-                        radius,
-                        radius * 2f));
+                        radius));
                 }
             }
 

tests/AcDream.App.Tests/Streaming/LandblockPhysicsPublisherTests.cs

@@ -462,6 +462,186 @@ public sealed class LandblockPhysicsPublisherTests
         Assert.Equal(0, fixture.Publisher.Diagnostics.StaticCylinderOwnerCount);
     }
 
+    /// <summary>
+    /// AP-155 parity (route independence). A Setup carrying only authored
+    /// Spheres (no CylSpheres) must register the SAME shapes — type, local
+    /// position, radius, scale — through the static publication path as
+    /// through <see cref="ShadowShapeBuilder.FromSetup"/>, the LIVE path.
+    /// Before the fix this site emitted a height-capped Cylinder instead
+    /// (base = origin - r*ẑ, height = 2r): same object, different narrow
+    /// phase depending on how it arrived.
+    /// </summary>
+    [Fact]
+    public void CompletePublication_SphereOnlySetup_MatchesFromSetupShapeForShape()
+    {
+        var fixture = Fixture();
+        var setup = new Setup();
+        setup.Spheres.Add(new Sphere
+        {
+            Origin = new Vector3(0.3f, -0.2f, 0.9f),
+            Radius = 0.55f,
+        });
+        setup.Spheres.Add(new Sphere
+        {
+            Origin = new Vector3(-0.1f, 0.4f, 1.4f),
+            Radius = 0.25f,
+        });
+        fixture.Cache.CacheSetup(SetupId, setup);
+
+        const float entScale = 1.3f;
+        WorldEntity entity = new()
+        {
+            Id = 0x80A9B401u,
+            SourceGfxObjOrSetupId = SetupId,
+            Position = Vector3.Zero,
+            Rotation = Quaternion.Identity,
+            Scale = entScale,
+            MeshRefs = Array.Empty<MeshRef>(),
+        };
+
+        Publish(fixture.Publisher, Build(FirstLandblock, [entity]));
+
+        // The LIVE-path oracle for the SAME Setup/scale.
+        IReadOnlyList<ShadowShape> expected =
+            ShadowShapeBuilder.FromSetup(setup, entScale, _ => false);
+        Assert.Equal(2, expected.Count);
+        Assert.All(
+            expected,
+            shape => Assert.Equal(ShadowCollisionType.Sphere, shape.CollisionType));
+
+        ShadowShape[] expectedOrdered =
+            expected.OrderBy(shape => shape.Radius).ToArray();
+        // Entity registered at world origin with identity rotation, so
+        // RegisterMultiPart's world composition (entityWorldPos +
+        // Transform(shape.LocalPosition, entityWorldRot)) reduces to exactly
+        // shape.LocalPosition — the static entry's world Position is directly
+        // comparable to FromSetup's LocalPosition.
+        ShadowEntry[] entries = fixture.Engine.ShadowObjects.AllEntriesForDebug()
+            .Where(entry => entry.EntityId == entity.Id)
+            .OrderBy(entry => entry.Radius)
+            .ToArray();
+
+        Assert.Equal(expectedOrdered.Length, entries.Length);
+        for (int i = 0; i < entries.Length; i++)
+        {
+            Assert.Equal(ShadowCollisionType.Sphere, entries[i].CollisionType);
+            Assert.Equal(expectedOrdered[i].LocalPosition, entries[i].Position);
+            Assert.Equal(expectedOrdered[i].Radius, entries[i].Radius);
+            Assert.Equal(expectedOrdered[i].Scale, entries[i].Scale);
+            // Review F4 (2026-08-07): assert, don't infer — the C4 lesson.
+            Assert.Equal(expectedOrdered[i].CylHeight, entries[i].CylHeight);
+        }
+    }
+
+    /// <summary>
+    /// AP-155 dispatch. A statically-published Sphere must actually run the
+    /// Sphere narrow phase (<c>CSphere::intersects_sphere</c> — true 3-D
+    /// distance) at query time, not the Cylinder narrow phase (XY distance +
+    /// flat Z-band). Geometry: a 1 m-radius "boulder" Setup Sphere centred at
+    /// world Z=2.0 (spans Z=[1,3]). A tall, narrow capsule mover's HEAD sphere
+    /// grazes the boulder's shoulder at Z~2.85 (0.85 m above the boulder's own
+    /// centre, out of its 1 m radius) with a 1.05 m lateral offset; its FOOT
+    /// sphere (Z~0.15) never comes close. At that height/offset the true
+    /// sphere's surface has tapered well inside the mover's path (curve-hit —
+    /// clean miss, ~0.2 m 3-D clearance), while the retired flat-capped
+    /// Cylinder never tapers and still fills the same footprint the whole
+    /// height of its cap (cap-hit — the 1.05 m offset sits ~0.10 m inside its
+    /// XY radius). The two verdicts differ; this asserts the Sphere one —
+    /// unobstructed straight-line arrival at the far side.
+    /// </summary>
+    [Fact]
+    public void CompletePublication_SphereOnlySetup_MoverGrazesShoulderAndPassesThroughUnobstructed()
+    {
+        var fixture = Fixture();
+        var setup = new Setup();
+        setup.Spheres.Add(new Sphere
+        {
+            Origin = new Vector3(0f, 0f, 2.0f),
+            Radius = 1.0f,
+        });
+        fixture.Cache.CacheSetup(SetupId, setup);
+
+        WorldEntity entity = new()
+        {
+            Id = 0x80A9B401u,
+            SourceGfxObjOrSetupId = SetupId,
+            Position = new Vector3(12f, 12f, 0f),
+            Rotation = Quaternion.Identity,
+            MeshRefs = Array.Empty<MeshRef>(),
+        };
+        Publish(fixture.Publisher, Build(FirstLandblock, [entity]));
+
+        // Sanity: the fix registered a Sphere, not a Cylinder — the dispatch
+        // this test exercises depends on it.
+        ShadowEntry registered = Assert.Single(
+            fixture.Engine.ShadowObjects.AllEntriesForDebug());
+        Assert.Equal(ShadowCollisionType.Sphere, registered.CollisionType);
+
+        var body = MakeGroundedBody(new Vector3(10.7f, 13.05f, 0f));
+        Vector3 target = new(13.3f, 13.05f, 0f);
+
+        ResolveResult result = fixture.Engine.ResolveWithTransition(
+            body.Position, target, 0xA9B40001u,
+            sphereRadius: 0.15f, sphereHeight: 3.0f,
+            stepUpHeight: 0.60f, stepDownHeight: 0.04f,
+            isOnGround: true, body: body,
+            moverFlags: ObjectInfoState.IsPlayer | ObjectInfoState.EdgeSlide,
+            movingEntityId: 0u);
+
+        Assert.True(
+            MathF.Abs(result.Position.X - target.X) < 0.05f
+                && MathF.Abs(result.Position.Y - target.Y) < 0.05f,
+            "Mover must clear the boulder unobstructed (true-sphere curve-hit "
+            + $"clears at this height/offset); got {result.Position}, wanted {target}.");
+
+        // Review F8 (2026-08-07): the POSITIVE control. Without it, the graze
+        // assertion above also passes when the shadow object is absent from
+        // the queried cell entirely (a membership/seed/flood regression) —
+        // the discriminating power lived only in an unreproducible sabotage
+        // run. Same publication, same cell, but aimed straight THROUGH the
+        // boulder's centre: the head sphere's closest approach to the centre
+        // is (0, 0, 0.85), |d| = 0.85 < radsum 1.15 — the true sphere MUST
+        // block this one. The pair proves reachable AND correctly shaped.
+        var throughBody = MakeGroundedBody(new Vector3(10.7f, 12f, 0f));
+        ResolveResult blockedResult = fixture.Engine.ResolveWithTransition(
+            throughBody.Position, new Vector3(13.3f, 12f, 0f), 0xA9B40001u,
+            sphereRadius: 0.15f, sphereHeight: 3.0f,
+            stepUpHeight: 0.60f, stepDownHeight: 0.04f,
+            isOnGround: true, body: throughBody,
+            moverFlags: ObjectInfoState.IsPlayer | ObjectInfoState.EdgeSlide,
+            movingEntityId: 0u);
+        Assert.True(
+            MathF.Abs(blockedResult.Position.X - 13.3f) >= 0.05f,
+            "Aiming straight through the boulder's centre must NOT arrive at "
+            + $"the far side; got {blockedResult.Position} — the sphere is "
+            + "either unregistered in cell 0xA9B40001 or not colliding.");
+    }
+
+    private static PhysicsBody MakeGroundedBody(Vector3 position)
+    {
+        var floorPlane = new Plane(Vector3.UnitZ, 0f);
+        var floorVerts = new[]
+        {
+            new Vector3(-100f, -100f, 0f),
+            new Vector3( 100f, -100f, 0f),
+            new Vector3( 100f,  100f, 0f),
+            new Vector3(-100f,  100f, 0f),
+        };
+        return new PhysicsBody
+        {
+            Position             = position,
+            Orientation          = Quaternion.Identity,
+            ContactPlaneValid    = true,
+            ContactPlane         = floorPlane,
+            ContactPlaneCellId   = 0xA9B40001u,
+            WalkablePolygonValid = true,
+            WalkablePlane        = floorPlane,
+            WalkableVertices     = floorVerts,
+            WalkableUp           = Vector3.UnitZ,
+            TransientState       = TransientStateFlags.Contact | TransientStateFlags.OnWalkable,
+        };
+    }
+
     [Fact]
     public void CompletePublication_BuildingShellNeverRegistersSetupCollision()
     {

tests/AcDream.Content.Tests/Ap155StaticSpherePopulationMeasurementTests.cs

@@ -0,0 +1,105 @@
+using System.Collections.Generic;
+using AcDream.Core.Physics;
+using DatReaderWriter;
+using DatReaderWriter.DBObjs;
+using DatReaderWriter.Enums;
+using DatReaderWriter.Options;
+
+namespace AcDream.Content.Tests;
+
+/// <summary>
+/// AP-155 population MEASUREMENT ONLY (contract
+/// <c>docs/research/2026-08-07-s2-static-sphere-contract.md</c>, "Measurement"
+/// section) — not a gate. Counts, over the installed <c>client_portal.dat</c>
+/// Setups (the same <c>dats.GetAllIdsOfType&lt;Setup&gt;()</c> enumeration
+/// <see cref="InstalledSetupCollisionReachabilityTests"/> and
+/// <see cref="InstalledSetupBspPrimitiveDispatchTests"/> already sweep), how
+/// many actually REACH the fixed static-publication Sphere emission — i.e.
+/// <see cref="ShadowShapeBuilder.FromSetup"/>'s production dispatch, at
+/// scale 1, emits ONLY <see cref="ShadowCollisionType.Sphere"/> shapes for
+/// them. That dispatch (not a raw "has Spheres, no CylSpheres" field read) is
+/// the correct population: a Setup can carry authored Spheres and STILL never
+/// reach the sphere branch if a physics-BSP part suppresses it (AP-152) — 99
+/// of the 3,605 "sphere-only, no cylinder" Setups the reachability sweep
+/// already counted fall into exactly that trap.
+/// </summary>
+public sealed class Ap155StaticSpherePopulationMeasurementTests
+{
+    [Fact]
+    public void InstalledSetups_SphereOnlyStaticPopulation_Measured()
+    {
+        string? datDir = ContentConformanceDats.ResolveDatDir();
+        if (datDir is null)
+        {
+            Console.WriteLine("SKIP: installed retail DAT directory is unavailable.");
+            return;
+        }
+
+        using var dats = new DatCollection(datDir, DatAccessType.Read);
+
+        // Production physics-BSP predicate — same as
+        // InstalledSetupBspPrimitiveDispatchTests / FlatCollisionAssetBuilder.cs:377-380.
+        var physicsBspCache = new Dictionary<uint, bool>();
+        bool HasPhysicsBsp(uint gfxObjId)
+        {
+            if (physicsBspCache.TryGetValue(gfxObjId, out bool cached))
+                return cached;
+            bool result =
+                dats.Portal.TryGet<GfxObj>(gfxObjId, out GfxObj? gfx)
+                && gfx is not null
+                && gfx.Flags.HasFlag(GfxObjFlags.HasPhysics)
+                && gfx.PhysicsBSP?.Root is not null
+                && gfx.VertexArray is not null;
+            physicsBspCache[gfxObjId] = result;
+            return result;
+        }
+
+        int totalSetups = 0;
+        int sphereOnlyReachable = 0;
+        var samples = new List<uint>();
+
+        foreach (uint id in dats.GetAllIdsOfType<Setup>())
+        {
+            if (!dats.Portal.TryGet<Setup>(id, out Setup? setup) || setup is null)
+                continue;
+            totalSetups++;
+
+            // The classifier: production FromSetup output, not raw Setup
+            // fields — this is what a landblock static entity built from
+            // this Setup actually registers.
+            var shapes = ShadowShapeBuilder.FromSetup(setup, 1f, HasPhysicsBsp);
+            if (shapes.Count == 0)
+                continue;
+
+            bool sphereOnly = true;
+            foreach (var shape in shapes)
+            {
+                if (shape.CollisionType != ShadowCollisionType.Sphere)
+                {
+                    sphereOnly = false;
+                    break;
+                }
+            }
+            if (!sphereOnly)
+                continue;
+
+            sphereOnlyReachable++;
+            if (samples.Count < 3)
+                samples.Add(id);
+        }
+
+        Console.WriteLine("===== AP-155 static-sphere population measurement =====");
+        Console.WriteLine($"Total installed Setups:                                {totalSetups}");
+        Console.WriteLine($"Reach the static Sphere emission (post-fix, production dispatch): {sphereOnlyReachable}");
+        Console.WriteLine("Three example object ids:");
+        foreach (uint sample in samples)
+            Console.WriteLine($"  0x{sample:X8}");
+        Console.WriteLine("=========================================================");
+
+        // Structural sanity only — this is a measurement, not a gate.
+        Assert.True(totalSetups > 0, "Expected the installed DAT to enumerate at least one Setup.");
+        Assert.True(
+            sphereOnlyReachable > 0,
+            "Expected at least one Setup to reach the static Sphere emission in the installed DAT.");
+    }
+}

tests/AcDream.Content.Tests/LandblockPhysicsContentBuilderStaticSphereTests.cs

@@ -0,0 +1,111 @@
+using System.Collections.Immutable;
+using System.Linq;
+using System.Numerics;
+using AcDream.Content;
+using AcDream.Core.Physics;
+using AcDream.Core.World;
+using DatReaderWriter.DBObjs;
+using DatReaderWriter.Types;
+
+namespace AcDream.Content.Tests;
+
+/// <summary>
+/// AP-155 parity (route independence) for the second static publication site,
+/// <see cref="LandblockPhysicsContentBuilder.PublishStaticCollision"/>. A
+/// Setup carrying only authored Spheres (no CylSpheres) must register the
+/// SAME shapes — type, local position, radius, scale — as
+/// <see cref="ShadowShapeBuilder.FromSetup"/>, the LIVE path. Before the fix
+/// this site emitted a height-capped Cylinder instead (base = origin - r*ẑ,
+/// height = 2r), identically to <c>LandblockPhysicsPublisher</c>'s copy of
+/// the same bug — see that class's tests
+/// (<c>LandblockPhysicsPublisherTests.CompletePublication_SphereOnlySetup_*</c>)
+/// for the dispatch-level (Cylinder-vs-Sphere narrow phase) proof; the two
+/// sites share the SAME <c>ShadowObjectRegistry</c>/<c>TransitionTypes</c>
+/// query code; this class only needs to prove ITS emission is correct.
+/// </summary>
+public sealed class LandblockPhysicsContentBuilderStaticSphereTests
+{
+    private const uint LandblockId = 0xA9B40000u;
+    private const uint SetupId = 0x02000042u;
+
+    [Fact]
+    public void PublishStaticCollision_SphereOnlySetup_MatchesFromSetupShapeForShape()
+    {
+        var setup = new Setup();
+        setup.Spheres.Add(new Sphere
+        {
+            Origin = new Vector3(0.3f, -0.2f, 0.9f),
+            Radius = 0.55f,
+        });
+        setup.Spheres.Add(new Sphere
+        {
+            Origin = new Vector3(-0.1f, 0.4f, 1.4f),
+            Radius = 0.25f,
+        });
+        FlatSetupCollision flatSetup = FlatCollisionAssetBuilder.FlattenSetup(setup);
+
+        const float entScale = 1.3f;
+        var entity = new WorldEntity
+        {
+            Id = 0x80A9B401u,
+            SourceGfxObjOrSetupId = SetupId,
+            Position = Vector3.Zero,
+            Rotation = Quaternion.Identity,
+            Scale = entScale,
+            MeshRefs = Array.Empty<MeshRef>(),
+        };
+        var landblock = new LoadedLandblock(
+            LandblockId,
+            new LandBlock { Terrain = new TerrainInfo[81], Height = new byte[81] },
+            new[] { entity });
+        var collisions = new LandblockCollisionBuild(
+            ImmutableDictionary<uint, FlatGfxObjCollisionAsset>.Empty,
+            ImmutableDictionary<uint, FlatSetupCollision>.Empty.Add(SetupId, flatSetup),
+            ImmutableDictionary<uint, FlatCellStructureCollisionAsset>.Empty,
+            ImmutableDictionary<uint, FlatEnvCellTopology>.Empty,
+            ImmutableArray<uint>.Empty,
+            ImmutableArray.Create(SetupId),
+            ImmutableArray<uint>.Empty);
+
+        var engine = new PhysicsEngine();
+        var cache = new PhysicsDataCache();
+        LandblockPhysicsContentBuilder.CachePreparedObjects(cache, collisions);
+
+        LandblockPhysicsContentBuilder.StaticCollisionPublication publication =
+            LandblockPhysicsContentBuilder.PublishStaticCollision(
+                engine, cache, landblock, collisions, origin: Vector3.Zero);
+
+        Assert.Equal(1, publication.SetupOwnerCount);
+        Assert.Equal(0, publication.BspOwnerCount);
+        Assert.Equal(0, publication.NoCollisionCount);
+
+        // The LIVE-path oracle for the SAME Setup/scale.
+        var expected = ShadowShapeBuilder.FromSetup(setup, entScale, _ => false);
+        Assert.Equal(2, expected.Count);
+        Assert.All(
+            expected,
+            shape => Assert.Equal(ShadowCollisionType.Sphere, shape.CollisionType));
+
+        ShadowShape[] expectedOrdered = expected.OrderBy(shape => shape.Radius).ToArray();
+        // Entity registered at world origin with identity rotation, so
+        // RegisterMultiPart's world composition (entityWorldPos +
+        // Transform(shape.LocalPosition, entityWorldRot)) reduces to exactly
+        // shape.LocalPosition — the static entry's world Position is directly
+        // comparable to FromSetup's LocalPosition.
+        ShadowEntry[] entries = engine.ShadowObjects.AllEntriesForDebug()
+            .Where(entry => entry.EntityId == entity.Id)
+            .OrderBy(entry => entry.Radius)
+            .ToArray();
+
+        Assert.Equal(expectedOrdered.Length, entries.Length);
+        for (int i = 0; i < entries.Length; i++)
+        {
+            Assert.Equal(ShadowCollisionType.Sphere, entries[i].CollisionType);
+            Assert.Equal(expectedOrdered[i].LocalPosition, entries[i].Position);
+            Assert.Equal(expectedOrdered[i].Radius, entries[i].Radius);
+            Assert.Equal(expectedOrdered[i].Scale, entries[i].Scale);
+            // Review F4 (2026-08-07): assert, don't infer — the C4 lesson.
+            Assert.Equal(expectedOrdered[i].CylHeight, entries[i].CylHeight);
+        }
+    }
+}

tests/AcDream.Core.Tests/Physics/ShadowObjectRegistryMultiPartTests.cs

@@ -241,6 +241,14 @@ public class ShadowObjectRegistryMultiPartTests
             radius: radius,
             cylHeight: radius * 2f);
 
+    private static ShadowShape Sph(float radius, Vector3 localPosition = default)
+        => ShadowShape.Sphere(
+            gfxObjId: 0u,
+            localPosition: localPosition,
+            localRotation: Quaternion.Identity,
+            scale: 1f,
+            radius: radius);
+
     /// <summary>
     /// A physics-BSP part shape. <paramref name="boundsCenter"/> defaults
     /// OFF-CENTRE because that is the DAT-real configuration: a GfxObj's
@@ -389,6 +397,40 @@ public class ShadowObjectRegistryMultiPartTests
         Assert.DoesNotContain(farCell, cylCells);
     }
 
+    /// <summary>
+    /// AP-155 (S2 contract, 2026-08-07). Retail's 10-sphere clamp
+    /// (<c>CObjCell::find_cell_list</c> @0x0052b9f0, <c>0x0052ba21 cmp
+    /// eax,0xa</c>) is a fixed-size destination-buffer limit on the CYLSPHERE
+    /// overload alone — it is not read by the Sphere-shape branch
+    /// <c>BuildFloodSpheres</c> takes as acdream's substitute for retail's
+    /// sorting-sphere overload (@0x0052b990, AP-157, still open): that branch
+    /// caps at <c>int.MaxValue</c>, i.e. not at all. Before this fix a static
+    /// Setup-Sphere entity registered as Cylinder shapes and so WAS subject to
+    /// this cap; after it, the same entity registers as Sphere shapes and
+    /// reaches this uncapped branch instead — verified here directly rather
+    /// than inferred from the source comment, matching
+    /// <see cref="BuildFloodSpheres_CapsCylSpheresAtTenButNeverTheBspParts"/>'s
+    /// eleventh-shape technique one branch over.
+    /// </summary>
+    [Fact]
+    public void BuildFloodSpheres_SphereBranchIsNeverCappedAtTen()
+    {
+        var far = new Vector3(0f, 72f, 0f);
+        uint ownCell = LbId | (uint)(1 * 8 + 1 + 1);   // (x=1, y=1)
+        uint farCell = LbId | (uint)(1 * 8 + 4 + 1);   // (x=1, y=4)
+
+        var spheres = new ShadowShape[11];
+        for (int i = 0; i < 10; i++)
+            spheres[i] = Sph(1f);
+        spheres[10] = Sph(1f, far);
+        List<uint> sphereCells = FloodCellsFor(spheres);
+
+        Assert.Contains(ownCell, sphereCells);
+        // The eleventh Sphere still floods — unlike the eleventh CylSphere in
+        // BuildFloodSpheres_CapsCylSpheresAtTenButNeverTheBspParts above.
+        Assert.Contains(farCell, sphereCells);
+    }
+
     /// <summary>
     /// The BoundsCentre is expressed in the SHAPE's own frame, so the part's
     /// LocalRotation must carry it — exactly as retail transforms the sphere