diff --git a/README.md b/README.md
index 138a991..7452b06 100644
--- a/README.md
+++ b/README.md
@@ -47,6 +47,8 @@ parity suite already witness released Box3D behavior for:
 - contact-begin facts
 - restitution mixing
 - transient torque lifetime
+- category/mask/group collision filtering
+- bullet CCD against kinematic bodies, including Box3D's next-step contact-event timing
 
 The production `Ymir.Box3D` boundary owns the native session ABI. The legacy
 snapshot `YmirSimulator.Step` contract now creates an isolated Box3D session,
@@ -93,6 +95,11 @@ smoke is still required before that is a repeatable packaging guarantee. Linux
 and macOS packages must be produced and smoked on their own release workers
 before those RIDs are advertised.
 
+The current package version is `0.3.0`. ABI v4 exposes Box3D body type,
+bullet, field-participation, and collision-filter configuration without
+exposing Box3D handles. These are Ymir contract fields, but their behavior is
+Box3D behavior.
+
 ## Cutover Rule
 
 A Ymir cutover is complete only when all runtime stepping, collision queries,
diff --git a/docs/architecture.md b/docs/architecture.md
index 4f8a989..c377e64 100644
--- a/docs/architecture.md
+++ b/docs/architecture.md
@@ -145,10 +145,11 @@ The native facade must remain boring:
 
 ## Persistence
 
-`gamecult.ymir.world_state.v1` appends planar direction and angular velocity to
-the v0 layout. The v0 reader is an explicit migration path; keys are not
-reassigned. Torque is transient command state and is intentionally absent.
-Version 1 is a compatibility world snapshot, not a complete retained-session
+`gamecult.ymir.world_state.v2` appends Box3D body type, bullet,
+field-participation, and collision filter arrays to the v1 layout. The v1 and
+v0 readers are explicit migration paths; keys are not reassigned. Torque is
+transient command state and is intentionally absent. Version 2 is a
+compatibility world snapshot, not a complete retained-session
 checkpoint: it does not preserve full shape, material, filter, session tuning,
 provenance, or warm contact state.
 
@@ -172,7 +173,7 @@ Box3D-backed sessions prove:
 1. fixed-step body state projection;
 2. begin/end/hit contact lifecycle;
 3. overlap and shape-cast lowering;
-4. continuous collision and projectile witnesses;
+4. continuous collision event timing and same-step Box3D cast witnesses;
 5. transient force and torque application;
 6. checkpoint reconstruction and replay;
 7. Aetheria gravity, tractor, pickup, and payload smokes.
diff --git a/docs/box3d-parity.md b/docs/box3d-parity.md
index 1cb7f92..cae67ca 100644
--- a/docs/box3d-parity.md
+++ b/docs/box3d-parity.md
@@ -21,7 +21,7 @@ the overlap, cast, pair-step, torque-lifetime, version, and ABI-layout
 operations used by the harness. This keeps Box3D's alpha C ABI out of Ymir's
 public managed contracts.
 
-Production ABI version 3 uses caller-owned blittable buffers, explicit cdecl,
+Production ABI version 4 uses caller-owned blittable buffers, explicit cdecl,
 fixed-width status/count values, compile-time C layout assertions, and a
 managed/native layout sentinel before opening a session. It adds explicit
 retained body mutations, one-shot force and torque operations, and a
@@ -30,6 +30,8 @@ stored contact key only long enough to correlate its separate event arrays;
 public Ymir facts never expose native contact identity. Planar direction maps to Box3D
 rotation about Y; angular velocity and transient torque remain Box3D state and
 commands rather than managed integration.
+ABI v4 additionally carries Box3D static/kinematic/dynamic selection, bullet
+CCD, category/mask/group filtering, and per-body radial-field participation.
 
 `tests/Ymir.Box3D.Parity` builds that facade through CMake and invokes it with
 source-generated .NET interop. Run it with:
@@ -58,6 +60,12 @@ is retained in the pinned submodule.
 - Restitution uses the maximum of the two shape materials.
 - Applied torque is transient and cleared by each world step; a continuous
   torque must be submitted again for the next step.
+- A negative Box3D group index suppresses collision within that group before
+  category/mask evaluation. Category and mask bits then decide eligible pairs.
+- Bullet CCD against a kinematic target prevents traversal during the fast
+  step, but Box3D v0.1.0 emits the typed contact event on the following step.
+  Same-step gameplay triggering therefore requires an explicit Box3D shape
+  cast; Ymir must not invent an earlier Begin event.
 
 ## Cut Line
 
diff --git a/docs/retained-session-contract.md b/docs/retained-session-contract.md
index a5920dd..cc770bb 100644
--- a/docs/retained-session-contract.md
+++ b/docs/retained-session-contract.md
@@ -38,7 +38,7 @@ The retained port accepts narrow operations with explicit meaning:
 - remove a body, rejecting an unknown id;
 - teleport a body;
 - set linear and angular velocity;
-- configure body shape, mass, type, and restitution;
+- configure body shape, mass, static/kinematic/dynamic type, and restitution;
 - apply one-shot force or torque;
 - step with a fixed delta, substep count, and typed fields;
 - dispose the session.
@@ -46,6 +46,10 @@ The retained port accepts narrow operations with explicit meaning:
 The current public slice implements those mutation and step operations.
 Retained-world overlap and cast queries at a named revision are the next
 library cut; the static compatibility queries do not satisfy that contract.
+Bullet, collision-filter, and field-participation profiles are currently
+spawn/restore definitions. Retained `Configure` changes radius, mass,
+static/kinematic/dynamic type, and restitution only. Changing the profile
+requires explicit remove-and-spawn until a typed profile command exists.
 
 Restore/import is the only path allowed to accept a complete world snapshot.
 There is no `Upsert`, generic patch bag, or omission-based removal.
@@ -73,7 +77,7 @@ chronology.
 
 - Box3D handles are process-local and never cross the contract.
 - DTO and SoA body arrays are projections.
-- `gamecult.ymir.world_state.v1` is an inspection/migration snapshot, not a
+- `gamecult.ymir.world_state.v2` is an inspection/migration snapshot, not a
   retained-session checkpoint.
 - Receipt and contact-episode ledgers are session metadata, not physics law.
 - Aetheria cargo, damage, loot, feedback, and scoring remain gameplay state
diff --git a/native/Ymir.Box3D/ymir_box3d.c b/native/Ymir.Box3D/ymir_box3d.c
index 9120c2c..6d3d0f8 100644
--- a/native/Ymir.Box3D/ymir_box3d.c
+++ b/native/Ymir.Box3D/ymir_box3d.c
@@ -85,6 +85,8 @@ typedef enum ymir_box3d_status
 typedef struct ymir_box3d_session_body_input
 {
     uint64_t stable_id;
+    uint64_t collision_category_bits;
+    uint64_t collision_mask_bits;
     float position_x;
     float position_y;
     float velocity_x;
@@ -97,6 +99,10 @@ typedef struct ymir_box3d_session_body_input
     float mass;
     float restitution;
     uint32_t is_static;
+    uint32_t is_kinematic;
+    uint32_t is_bullet;
+    uint32_t participates_in_fields;
+    int32_t collision_group_index;
 } ymir_box3d_session_body_input;
 
 typedef struct ymir_box3d_radial_field_input
@@ -182,6 +188,12 @@ typedef struct ymir_box3d_session_body
     float mass;
     float restitution;
     uint32_t is_static;
+    uint32_t is_kinematic;
+    uint32_t is_bullet;
+    uint32_t participates_in_fields;
+    uint64_t collision_category_bits;
+    uint64_t collision_mask_bits;
+    int32_t collision_group_index;
     int seen;
 } ymir_box3d_session_body;
 
@@ -206,7 +218,7 @@ typedef struct ymir_box3d_session
 } ymir_box3d_session;
 
 _Static_assert(sizeof(ymir_box3d_status) == sizeof(int32_t), "Ymir Box3D status ABI must be 32-bit");
-_Static_assert(sizeof(ymir_box3d_session_body_input) == 56, "Unexpected Ymir Box3D body input layout");
+_Static_assert(sizeof(ymir_box3d_session_body_input) == 88, "Unexpected Ymir Box3D body input layout");
 _Static_assert(sizeof(ymir_box3d_radial_field_input) == 16, "Unexpected Ymir Box3D field layout");
 _Static_assert(sizeof(ymir_box3d_session_body_output) == 40, "Unexpected Ymir Box3D body output layout");
 _Static_assert(sizeof(ymir_box3d_session_contact_output) == 40, "Unexpected Ymir Box3D contact layout");
@@ -235,7 +247,17 @@ static int ymir_session_body_input_is_valid(const ymir_box3d_session_body_input*
            ymir_is_finite(input->torque) &&
            ymir_is_finite(input->radius) && input->radius > 0.0f && ymir_is_finite(input->mass) &&
            (input->is_static != 0 || input->mass > 0.0f) && ymir_is_finite(input->restitution) &&
-           input->restitution >= 0.0f;
+           input->restitution >= 0.0f && !(input->is_static != 0 && input->is_kinematic != 0) &&
+           input->collision_category_bits != 0;
+}
+
+static b3BodyType ymir_session_body_type(const ymir_box3d_session_body_input* input)
+{
+    if (input->is_static != 0)
+    {
+        return b3_staticBody;
+    }
+    return input->is_kinematic != 0 ? b3_kinematicBody : b3_dynamicBody;
 }
 
 static b3Quat ymir_session_rotation(float direction_x, float direction_y)
@@ -374,7 +396,7 @@ static ymir_box3d_status ymir_session_create_body(
     ymir_box3d_session_body* output)
 {
     b3BodyDef body_def = b3DefaultBodyDef();
-    body_def.type = input->is_static != 0 ? b3_staticBody : b3_dynamicBody;
+    body_def.type = ymir_session_body_type(input);
     body_def.position = ymir_vec(input->position_x, input->position_y);
     body_def.rotation = ymir_session_rotation(input->direction_x, input->direction_y);
     body_def.linearVelocity = ymir_vec(input->velocity_x, input->velocity_y);
@@ -383,6 +405,7 @@ static ymir_box3d_status ymir_session_create_body(
     body_def.motionLocks.angularX = true;
     body_def.motionLocks.angularZ = true;
     body_def.enableSleep = false;
+    body_def.isBullet = input->is_bullet != 0;
     b3BodyId body_id = b3CreateBody(session->world_id, &body_def);
     if (B3_IS_NULL(body_id))
     {
@@ -394,6 +417,9 @@ static ymir_box3d_status ymir_session_create_body(
     shape_def.density = input->is_static != 0 ? 0.0f : ymir_session_density(input->mass, input->radius);
     shape_def.baseMaterial.friction = 0.0f;
     shape_def.baseMaterial.restitution = input->restitution;
+    shape_def.filter.categoryBits = input->collision_category_bits;
+    shape_def.filter.maskBits = input->collision_mask_bits;
+    shape_def.filter.groupIndex = input->collision_group_index;
     shape_def.enableContactEvents = true;
     shape_def.enableHitEvents = true;
     b3Sphere sphere = {{0.0f, 0.0f, 0.0f}, input->radius};
@@ -420,6 +446,12 @@ static ymir_box3d_status ymir_session_create_body(
         .mass = input->mass,
         .restitution = input->restitution,
         .is_static = input->is_static != 0,
+        .is_kinematic = input->is_kinematic != 0,
+        .is_bullet = input->is_bullet != 0,
+        .participates_in_fields = input->participates_in_fields != 0,
+        .collision_category_bits = input->collision_category_bits,
+        .collision_mask_bits = input->collision_mask_bits,
+        .collision_group_index = input->collision_group_index,
         .seen = 1,
     };
     return YMIR_BOX3D_OK;
@@ -429,13 +461,31 @@ static void ymir_session_update_body(
     ymir_box3d_session_body* body,
     const ymir_box3d_session_body_input* input)
 {
-    int type_changed = body->is_static != (input->is_static != 0);
+    int type_changed = body->is_static != (input->is_static != 0) ||
+        body->is_kinematic != (input->is_kinematic != 0);
     int radius_changed = body->radius != input->radius;
     int mass_changed = body->mass != input->mass;
 
     if (type_changed)
     {
-        b3Body_SetType(body->body_id, input->is_static != 0 ? b3_staticBody : b3_dynamicBody);
+        b3Body_SetType(body->body_id, ymir_session_body_type(input));
+    }
+
+    if (body->is_bullet != (input->is_bullet != 0))
+    {
+        b3Body_SetBullet(body->body_id, input->is_bullet != 0);
+    }
+
+    if (body->collision_category_bits != input->collision_category_bits ||
+        body->collision_mask_bits != input->collision_mask_bits ||
+        body->collision_group_index != input->collision_group_index)
+    {
+        b3Filter filter = {
+            .categoryBits = input->collision_category_bits,
+            .maskBits = input->collision_mask_bits,
+            .groupIndex = input->collision_group_index,
+        };
+        b3Shape_SetFilter(body->shape_id, filter, true);
     }
 
     if (radius_changed)
@@ -487,6 +537,12 @@ static void ymir_session_update_body(
     body->mass = input->mass;
     body->restitution = input->restitution;
     body->is_static = input->is_static != 0;
+    body->is_kinematic = input->is_kinematic != 0;
+    body->is_bullet = input->is_bullet != 0;
+    body->participates_in_fields = input->participates_in_fields != 0;
+    body->collision_category_bits = input->collision_category_bits;
+    body->collision_mask_bits = input->collision_mask_bits;
+    body->collision_group_index = input->collision_group_index;
     body->seen = 1;
 }
 
@@ -1150,7 +1206,7 @@ YMIR_EXPORT ymir_box3d_torque_result YMIR_CALL ymir_box3d_torque_lifetime(float
 
 YMIR_EXPORT uint32_t YMIR_CALL ymir_box3d_get_abi_version(void)
 {
-    return 3;
+    return 4;
 }
 
 YMIR_EXPORT int32_t YMIR_CALL ymir_box3d_get_abi_layout(
@@ -1403,10 +1459,12 @@ YMIR_EXPORT int32_t YMIR_CALL ymir_box3d_session_configure(
     float radius,
     float mass,
     float restitution,
-    uint32_t is_static)
+    uint32_t is_static,
+    uint32_t is_kinematic)
 {
     if (session == NULL || !ymir_is_finite(radius) || radius <= 0.0f || !ymir_is_finite(mass) ||
-        (is_static == 0 && mass <= 0.0f) || !ymir_is_finite(restitution) || restitution < 0.0f)
+        (is_static == 0 && mass <= 0.0f) || (is_static != 0 && is_kinematic != 0) ||
+        !ymir_is_finite(restitution) || restitution < 0.0f)
     {
         return YMIR_BOX3D_INVALID_ARGUMENT;
     }
@@ -1416,12 +1474,14 @@ YMIR_EXPORT int32_t YMIR_CALL ymir_box3d_session_configure(
         return YMIR_BOX3D_INVALID_ARGUMENT;
     }
     ymir_box3d_session_body* body = session->bodies + index;
-    int type_changed = body->is_static != (is_static != 0);
+    int type_changed = body->is_static != (is_static != 0) || body->is_kinematic != (is_kinematic != 0);
     int radius_changed = body->radius != radius;
     int mass_changed = body->mass != mass;
     if (type_changed)
     {
-        b3Body_SetType(body->body_id, is_static != 0 ? b3_staticBody : b3_dynamicBody);
+        b3Body_SetType(
+            body->body_id,
+            is_static != 0 ? b3_staticBody : (is_kinematic != 0 ? b3_kinematicBody : b3_dynamicBody));
     }
     if (radius_changed)
     {
@@ -1442,6 +1502,7 @@ YMIR_EXPORT int32_t YMIR_CALL ymir_box3d_session_configure(
     body->mass = mass;
     body->restitution = restitution;
     body->is_static = is_static != 0;
+    body->is_kinematic = is_kinematic != 0;
     ymir_box3d_status status = ymir_session_drain_contact_events(session, YMIR_DRAIN_END, 1);
     return status;
 }
@@ -1526,7 +1587,7 @@ YMIR_EXPORT int32_t YMIR_CALL ymir_box3d_session_step(
     for (int body_index = 0; body_index < session->body_count; ++body_index)
     {
         ymir_box3d_session_body* body = session->bodies + body_index;
-        if (body->is_static)
+        if (body->is_static || body->is_kinematic)
         {
             body->pending_torque = 0.0f;
             continue;
@@ -1538,6 +1599,11 @@ YMIR_EXPORT int32_t YMIR_CALL ymir_box3d_session_step(
         }
         body->pending_torque = 0.0f;
 
+        if (!body->participates_in_fields)
+        {
+            continue;
+        }
+
         b3Pos position = b3Body_GetPosition(body->body_id);
         float acceleration_x = 0.0f;
         float acceleration_y = 0.0f;
diff --git a/src/Ymir.Box3D/Box3DNative.cs b/src/Ymir.Box3D/Box3DNative.cs
index f250b7b..fb7ff83 100644
--- a/src/Ymir.Box3D/Box3DNative.cs
+++ b/src/Ymir.Box3D/Box3DNative.cs
@@ -110,7 +110,8 @@ internal static partial class Box3DNative
         float radius,
         float mass,
         float restitution,
-        uint isStatic);
+        uint isStatic,
+        uint isKinematic);
 
     [LibraryImport(LibraryName)]
     [UnmanagedCallConv(CallConvs = [typeof(CallConvCdecl)])]
@@ -191,6 +192,8 @@ internal sealed class Box3DSessionHandle : SafeHandleZeroOrMinusOneIsInvalid
 [StructLayout(LayoutKind.Sequential)]
 internal readonly record struct Box3DBodyInput(
     ulong StableId,
+    ulong CollisionCategoryBits,
+    ulong CollisionMaskBits,
     float PositionX,
     float PositionZ,
     float VelocityX,
@@ -202,7 +205,11 @@ internal readonly record struct Box3DBodyInput(
     float Radius,
     float Mass,
     float Restitution,
-    uint IsStatic);
+    uint IsStatic,
+    uint IsKinematic,
+    uint IsBullet,
+    uint ParticipatesInFields,
+    int CollisionGroupIndex);
 
 [StructLayout(LayoutKind.Sequential)]
 internal readonly record struct Box3DRadialField(
diff --git a/src/Ymir.Box3D/Box3DSession.cs b/src/Ymir.Box3D/Box3DSession.cs
index b6a9035..a395470 100644
--- a/src/Ymir.Box3D/Box3DSession.cs
+++ b/src/Ymir.Box3D/Box3DSession.cs
@@ -4,6 +4,8 @@ namespace Ymir.Box3D;
 
 internal readonly record struct Box3DBody(
     ulong StableId,
+    ulong CollisionCategoryBits,
+    ulong CollisionMaskBits,
     float PositionX,
     float PositionZ,
     float VelocityX,
@@ -15,7 +17,11 @@ internal readonly record struct Box3DBody(
     float Radius,
     float Mass,
     float Restitution,
-    bool IsStatic);
+    bool IsStatic,
+    bool IsKinematic,
+    bool IsBullet,
+    bool ParticipatesInFields,
+    int CollisionGroupIndex);
 
 internal readonly record struct Box3DField(float PositionX, float PositionZ, float Strength, float Radius);
 
@@ -63,7 +69,7 @@ internal readonly record struct Box3DContactFact(
 
 internal sealed class Box3DSession : IDisposable
 {
-    internal const uint AbiVersion = 3;
+    internal const uint AbiVersion = 4;
     internal const int DefaultSubstepCount = 4;
 
     private readonly Box3DSessionHandle _handle;
@@ -90,6 +96,8 @@ internal sealed class Box3DSession : IDisposable
             var body = bodies[i];
             native[i] = new Box3DBodyInput(
                 body.StableId,
+                body.CollisionCategoryBits,
+                body.CollisionMaskBits,
                 body.PositionX,
                 body.PositionZ,
                 body.VelocityX,
@@ -101,7 +109,11 @@ internal sealed class Box3DSession : IDisposable
                 body.Radius,
                 body.Mass,
                 body.Restitution,
-                body.IsStatic ? 1u : 0u);
+                body.IsStatic ? 1u : 0u,
+                body.IsKinematic ? 1u : 0u,
+                body.IsBullet ? 1u : 0u,
+                body.ParticipatesInFields ? 1u : 0u,
+                body.CollisionGroupIndex);
         }
 
         fixed (Box3DBodyInput* pointer = native)
@@ -155,12 +167,13 @@ internal sealed class Box3DSession : IDisposable
         float radius,
         float mass,
         float restitution,
-        bool isStatic)
+        bool isStatic,
+        bool isKinematic)
     {
         ThrowIfDisposed();
         ThrowIfMutationFailed(
             Box3DNative.ymir_box3d_session_configure(
-                _handle, stableId, radius, mass, restitution, isStatic ? 1u : 0u),
+                _handle, stableId, radius, mass, restitution, isStatic ? 1u : 0u, isKinematic ? 1u : 0u),
             "configure body");
     }
 
@@ -368,6 +381,8 @@ internal sealed class Box3DSession : IDisposable
 
     private static Box3DBodyInput ToNative(Box3DBody body) => new(
         body.StableId,
+        body.CollisionCategoryBits,
+        body.CollisionMaskBits,
         body.PositionX,
         body.PositionZ,
         body.VelocityX,
@@ -379,7 +394,11 @@ internal sealed class Box3DSession : IDisposable
         body.Radius,
         body.Mass,
         body.Restitution,
-        body.IsStatic ? 1u : 0u);
+        body.IsStatic ? 1u : 0u,
+        body.IsKinematic ? 1u : 0u,
+        body.IsBullet ? 1u : 0u,
+        body.ParticipatesInFields ? 1u : 0u,
+        body.CollisionGroupIndex);
 
     private void ThrowIfDisposed() => ObjectDisposedException.ThrowIf(_disposed, this);
 }
diff --git a/src/Ymir.Box3D/Ymir.Box3D.csproj b/src/Ymir.Box3D/Ymir.Box3D.csproj
index 8d5c0f2..58b2df9 100644
--- a/src/Ymir.Box3D/Ymir.Box3D.csproj
+++ b/src/Ymir.Box3D/Ymir.Box3D.csproj
@@ -9,7 +9,7 @@
     <AssemblyName>Ymir.Box3D</AssemblyName>
     <Description>Native ABI boundary between Ymir sessions and pinned Box3D.</Description>
     <PackageId>GameCult.Ymir.Box3D</PackageId>
-    <Version>0.2.0</Version>
+    <Version>0.3.0</Version>
     <Authors>GameCult</Authors>
     <IsPackable>true</IsPackable>
     <PackageReadmeFile>README.md</PackageReadmeFile>
diff --git a/src/Ymir.Core/PhysicsModel.cs b/src/Ymir.Core/PhysicsModel.cs
index 188215c..9ed51cc 100644
--- a/src/Ymir.Core/PhysicsModel.cs
+++ b/src/Ymir.Core/PhysicsModel.cs
@@ -21,7 +21,13 @@ public sealed record PhysicsBody(
     float Restitution = 0.2f,
     Vec2? Direction = null,
     float AngularVelocity = 0.0f,
-    float Torque = 0.0f);
+    float Torque = 0.0f,
+    bool IsKinematic = false,
+    bool IsBullet = false,
+    bool ParticipatesInFields = true,
+    ulong CollisionCategoryBits = 1UL,
+    ulong CollisionMaskBits = ulong.MaxValue,
+    int CollisionGroupIndex = 0);
 
 public sealed record RadialField(
     string Id,
diff --git a/src/Ymir.Core/RetainedSessionModel.cs b/src/Ymir.Core/RetainedSessionModel.cs
index a30ea72..7f51f20 100644
--- a/src/Ymir.Core/RetainedSessionModel.cs
+++ b/src/Ymir.Core/RetainedSessionModel.cs
@@ -29,7 +29,8 @@ public sealed record YmirConfigureBodyCommand(
     float Radius,
     float Mass,
     bool IsStatic,
-    float Restitution);
+    float Restitution,
+    bool IsKinematic = false);
 
 public sealed record YmirApplyForceCommand(
     YmirCommandHeader Header,
diff --git a/src/Ymir.Core/YmirServicePublicationDocument.cs b/src/Ymir.Core/YmirServicePublicationDocument.cs
index 615692b..4770757 100644
--- a/src/Ymir.Core/YmirServicePublicationDocument.cs
+++ b/src/Ymir.Core/YmirServicePublicationDocument.cs
@@ -53,7 +53,7 @@ public sealed class YmirOperatorStateDocument
     public string BatchKernel { get; set; } = "";
 
     [Key(5)]
-    public string Persistence { get; set; } = "CultCache gamecult.ymir.world_state.v1; explicit v0 read migration";
+    public string Persistence { get; set; } = "CultCache gamecult.ymir.world_state.v2; explicit v1/v0 read migration";
 
     [Key(6)]
     public string UpdatedAtUtc { get; set; } = "";
@@ -90,7 +90,7 @@ public static class YmirServicePublication
             "stable GameCult id to transient Box3D handle projection",
             "Box3D-backed circle overlap and cast queries over submitted bodies",
             "deterministic result ordering",
-            "CultCache world snapshot v1 with explicit v0 read migration",
+            "CultCache world snapshot v2 with explicit v1/v0 read migration",
             "diagnostic Eve publication"
         ],
         DoesNotOwn =
@@ -115,7 +115,7 @@ public static class YmirServicePublication
         StateOwner = "In-process retained Box3D sessions, isolated snapshot steps, and diagnostic projections",
         NumericSubstrate = "Box3D v0.1.0 (C17)",
         BatchKernel = "Box3D native solver; Ymir does not own physics algorithms",
-        Persistence = "CultCache gamecult.ymir.world_state.v1; explicit v0 read migration",
+        Persistence = "CultCache gamecult.ymir.world_state.v2; explicit v1/v0 read migration",
         UpdatedAtUtc = FormatUtc(now)
     };
 
diff --git a/src/Ymir.Core/YmirSession.cs b/src/Ymir.Core/YmirSession.cs
index e963e6c..71f5dd3 100644
--- a/src/Ymir.Core/YmirSession.cs
+++ b/src/Ymir.Core/YmirSession.cs
@@ -217,6 +217,7 @@ public sealed class YmirSession : IDisposable
                 writer.Write(command.Mass);
                 writer.Write(command.IsStatic);
                 writer.Write(command.Restitution);
+                writer.Write(command.IsKinematic);
             });
             if (Preflight(command.Header, fingerprint, "body.configure") is { } previous)
             {
@@ -228,6 +229,7 @@ public sealed class YmirSession : IDisposable
             }
             if (!float.IsFinite(command.Radius) || command.Radius <= 0.0f ||
                 !float.IsFinite(command.Mass) || (!command.IsStatic && command.Mass <= 0.0f) ||
+                (command.IsStatic && command.IsKinematic) ||
                 !float.IsFinite(command.Restitution) || command.Restitution < 0.0f)
             {
                 return RejectAndStore(command.Header, fingerprint, "body.configure", YmirCommandError.InvalidCommand);
@@ -235,12 +237,19 @@ public sealed class YmirSession : IDisposable
 
             RunNative(() =>
             {
-                _native.Configure(key, command.Radius, command.Mass, command.Restitution, command.IsStatic);
+                _native.Configure(
+                    key,
+                    command.Radius,
+                    command.Mass,
+                    command.Restitution,
+                    command.IsStatic,
+                    command.IsKinematic);
                 _bodies[command.BodyId] = body with
                 {
                     Radius = command.Radius,
                     Mass = command.Mass,
                     IsStatic = command.IsStatic,
+                    IsKinematic = command.IsKinematic,
                     Restitution = command.Restitution
                 };
                 UpdateBodyProjection(_native.CopyBodies());
@@ -267,7 +276,7 @@ public sealed class YmirSession : IDisposable
             {
                 return RejectAndStore(command.Header, fingerprint, "body.apply_force", YmirCommandError.UnknownBody);
             }
-            if (body.IsStatic)
+            if (body.IsStatic || body.IsKinematic)
             {
                 return RejectAndStore(command.Header, fingerprint, "body.apply_force", YmirCommandError.StaticBody);
             }
@@ -299,7 +308,7 @@ public sealed class YmirSession : IDisposable
             {
                 return RejectAndStore(command.Header, fingerprint, "body.apply_torque", YmirCommandError.UnknownBody);
             }
-            if (body.IsStatic)
+            if (body.IsStatic || body.IsKinematic)
             {
                 return RejectAndStore(command.Header, fingerprint, "body.apply_torque", YmirCommandError.StaticBody);
             }
@@ -791,6 +800,8 @@ public sealed class YmirSession : IDisposable
         var direction = DirectionOrDefault(body.Direction);
         return new Box3DBody(
             key,
+            body.CollisionCategoryBits,
+            body.CollisionMaskBits,
             body.Position.X,
             body.Position.Y,
             body.Velocity.X,
@@ -802,7 +813,11 @@ public sealed class YmirSession : IDisposable
             body.Radius,
             body.Mass,
             body.Restitution,
-            body.IsStatic);
+            body.IsStatic,
+            body.IsKinematic,
+            body.IsBullet,
+            body.ParticipatesInFields,
+            body.CollisionGroupIndex);
     }
 
     private static Vec2 DirectionOrDefault(Vec2? direction) =>
@@ -858,7 +873,9 @@ public sealed class YmirSession : IDisposable
         if (string.IsNullOrWhiteSpace(body.Id) || !Finite(body.Position) || !Finite(body.Velocity) ||
             !float.IsFinite(body.Radius) || body.Radius <= 0.0f ||
             !float.IsFinite(body.Mass) || (!body.IsStatic && body.Mass <= 0.0f) ||
+            (body.IsStatic && body.IsKinematic) ||
             !float.IsFinite(body.Restitution) || body.Restitution < 0.0f ||
+            body.CollisionCategoryBits == 0 ||
             (body.Direction is { } direction && !ValidDirection(direction)) ||
             !float.IsFinite(body.AngularVelocity) || !float.IsFinite(body.Torque) ||
             (!allowTorque && body.Torque != 0.0f))
@@ -918,6 +935,12 @@ public sealed class YmirSession : IDisposable
         }
         writer.Write(body.AngularVelocity);
         writer.Write(body.Torque);
+        writer.Write(body.IsKinematic);
+        writer.Write(body.IsBullet);
+        writer.Write(body.ParticipatesInFields);
+        writer.Write(body.CollisionCategoryBits);
+        writer.Write(body.CollisionMaskBits);
+        writer.Write(body.CollisionGroupIndex);
     }
 
     private static void WriteField(BinaryWriter writer, RadialField? field)
diff --git a/src/Ymir.Core/YmirSoAWorld.cs b/src/Ymir.Core/YmirSoAWorld.cs
index 4117af7..3985ca1 100644
--- a/src/Ymir.Core/YmirSoAWorld.cs
+++ b/src/Ymir.Core/YmirSoAWorld.cs
@@ -18,6 +18,12 @@ public sealed class YmirSoAWorld
     public float[] Mass { get; set; } = [];
     public float[] DynamicMask { get; set; } = [];
     public float[] Restitution { get; set; } = [];
+    public float[] KinematicMask { get; set; } = [];
+    public float[] BulletMask { get; set; } = [];
+    public float[] FieldParticipationMask { get; set; } = [];
+    public ulong[] CollisionCategoryBits { get; set; } = [];
+    public ulong[] CollisionMaskBits { get; set; } = [];
+    public int[] CollisionGroupIndex { get; set; } = [];
     public string[] FieldIds { get; set; } = [];
     public float[] FieldPositionX { get; set; } = [];
     public float[] FieldPositionY { get; set; } = [];
@@ -49,6 +55,12 @@ public sealed class YmirSoAWorld
             Mass = bodies.Select(body => body.Mass).ToArray(),
             DynamicMask = bodies.Select(body => body.IsStatic ? 0.0f : 1.0f).ToArray(),
             Restitution = bodies.Select(body => body.Restitution).ToArray(),
+            KinematicMask = bodies.Select(body => body.IsKinematic ? 1.0f : 0.0f).ToArray(),
+            BulletMask = bodies.Select(body => body.IsBullet ? 1.0f : 0.0f).ToArray(),
+            FieldParticipationMask = bodies.Select(body => body.ParticipatesInFields ? 1.0f : 0.0f).ToArray(),
+            CollisionCategoryBits = bodies.Select(body => body.CollisionCategoryBits).ToArray(),
+            CollisionMaskBits = bodies.Select(body => body.CollisionMaskBits).ToArray(),
+            CollisionGroupIndex = bodies.Select(body => body.CollisionGroupIndex).ToArray(),
             FieldIds = fields.Select(field => field.Id).ToArray(),
             FieldPositionX = fields.Select(field => field.Position.X).ToArray(),
             FieldPositionY = fields.Select(field => field.Position.Y).ToArray(),
@@ -70,7 +82,13 @@ public sealed class YmirSoAWorld
                 Restitution[i],
                 new Vec2(DirectionX[i], DirectionY[i]),
                 AngularVelocity[i],
-                Torque[i]))
+                Torque[i],
+                KinematicMask[i] > 0.0f,
+                BulletMask[i] > 0.0f,
+                FieldParticipationMask[i] > 0.0f,
+                CollisionCategoryBits[i],
+                CollisionMaskBits[i],
+                CollisionGroupIndex[i]))
             .ToArray(),
         Enumerable.Range(0, FieldCount)
             .Select(i => new RadialField(
@@ -96,6 +114,12 @@ public sealed class YmirSoAWorld
         Mass = (float[])Mass.Clone(),
         DynamicMask = (float[])DynamicMask.Clone(),
         Restitution = (float[])Restitution.Clone(),
+        KinematicMask = (float[])KinematicMask.Clone(),
+        BulletMask = (float[])BulletMask.Clone(),
+        FieldParticipationMask = (float[])FieldParticipationMask.Clone(),
+        CollisionCategoryBits = (ulong[])CollisionCategoryBits.Clone(),
+        CollisionMaskBits = (ulong[])CollisionMaskBits.Clone(),
+        CollisionGroupIndex = (int[])CollisionGroupIndex.Clone(),
         FieldIds = (string[])FieldIds.Clone(),
         FieldPositionX = (float[])FieldPositionX.Clone(),
         FieldPositionY = (float[])FieldPositionY.Clone(),
@@ -125,6 +149,16 @@ public sealed class YmirSoAWorld
                 throw new ArgumentOutOfRangeException(nameof(Mass), "Dynamic body mass must be positive.");
             }
 
+            if (DynamicMask[i] <= 0.0f && KinematicMask[i] > 0.0f)
+            {
+                throw new ArgumentException("A body cannot be both static and kinematic.");
+            }
+
+            if (CollisionCategoryBits[i] == 0)
+            {
+                throw new ArgumentOutOfRangeException(nameof(CollisionCategoryBits), "Collision category bits must be non-zero.");
+            }
+
             var directionLengthSquared = DirectionX[i] * DirectionX[i] + DirectionY[i] * DirectionY[i];
             if (!float.IsFinite(directionLengthSquared) || directionLengthSquared <= 1.0e-8f)
             {
@@ -158,6 +192,7 @@ public sealed class YmirSoAWorld
     {
         var expected = BodyIds.Length;
         FillMissingAngularState(expected);
+        FillMissingCollisionState(expected);
         foreach (var length in new[]
                  {
                      PositionX.Length,
@@ -171,7 +206,13 @@ public sealed class YmirSoAWorld
                      Radius.Length,
                      Mass.Length,
                      DynamicMask.Length,
-                     Restitution.Length
+                     Restitution.Length,
+                     KinematicMask.Length,
+                     BulletMask.Length,
+                     FieldParticipationMask.Length,
+                     CollisionCategoryBits.Length,
+                     CollisionMaskBits.Length,
+                     CollisionGroupIndex.Length
                  })
         {
             if (length != expected)
@@ -181,6 +222,19 @@ public sealed class YmirSoAWorld
         }
     }
 
+    private void FillMissingCollisionState(int expected)
+    {
+        if (KinematicMask.Length == 0 && expected > 0) KinematicMask = new float[expected];
+        if (BulletMask.Length == 0 && expected > 0) BulletMask = new float[expected];
+        if (FieldParticipationMask.Length == 0 && expected > 0)
+            FieldParticipationMask = Enumerable.Repeat(1.0f, expected).ToArray();
+        if (CollisionCategoryBits.Length == 0 && expected > 0)
+            CollisionCategoryBits = Enumerable.Repeat(1UL, expected).ToArray();
+        if (CollisionMaskBits.Length == 0 && expected > 0)
+            CollisionMaskBits = Enumerable.Repeat(ulong.MaxValue, expected).ToArray();
+        if (CollisionGroupIndex.Length == 0 && expected > 0) CollisionGroupIndex = new int[expected];
+    }
+
     private void FillMissingAngularState(int expected)
     {
         if (DirectionX.Length == 0 && expected > 0)
diff --git a/src/Ymir.Core/YmirWorldSession.cs b/src/Ymir.Core/YmirWorldSession.cs
index fa033ac..ad8f01f 100644
--- a/src/Ymir.Core/YmirWorldSession.cs
+++ b/src/Ymir.Core/YmirWorldSession.cs
@@ -53,6 +53,8 @@ internal sealed class YmirWorldSession : IDisposable
                 indicesByKey.Add(key, i);
                 bodies[i] = new Box3DBody(
                     key,
+                    world.CollisionCategoryBits[i],
+                    world.CollisionMaskBits[i],
                     world.PositionX[i],
                     world.PositionY[i],
                     world.VelocityX[i],
@@ -64,7 +66,11 @@ internal sealed class YmirWorldSession : IDisposable
                     world.Radius[i],
                     world.Mass[i],
                     world.Restitution[i],
-                    world.DynamicMask[i] <= 0.0f);
+                    world.DynamicMask[i] <= 0.0f,
+                    world.KinematicMask[i] > 0.0f,
+                    world.BulletMask[i] > 0.0f,
+                    world.FieldParticipationMask[i] > 0.0f,
+                    world.CollisionGroupIndex[i]);
             }
 
             Array.Sort(bodies, static (left, right) => left.StableId.CompareTo(right.StableId));
diff --git a/src/Ymir.Core/YmirWorldStateDocument.cs b/src/Ymir.Core/YmirWorldStateDocument.cs
index 3b9b2cf..8878029 100644
--- a/src/Ymir.Core/YmirWorldStateDocument.cs
+++ b/src/Ymir.Core/YmirWorldStateDocument.cs
@@ -167,6 +167,76 @@ public sealed class YmirWorldStateDocumentV1
     };
 }
 
+[CultDocument("gamecult.ymir.world_state", "gamecult.ymir.world_state.v2")]
+[MessagePackObject]
+public sealed class YmirWorldStateDocumentV2
+{
+    [Key(0), CultName] public string WorldId { get; set; } = "default";
+    [Key(1)] public float Time { get; set; }
+    [Key(2)] public string[] BodyIds { get; set; } = [];
+    [Key(3)] public float[] PositionX { get; set; } = [];
+    [Key(4)] public float[] PositionY { get; set; } = [];
+    [Key(5)] public float[] VelocityX { get; set; } = [];
+    [Key(6)] public float[] VelocityY { get; set; } = [];
+    [Key(7)] public float[] Radius { get; set; } = [];
+    [Key(8)] public float[] Mass { get; set; } = [];
+    [Key(9)] public float[] DynamicMask { get; set; } = [];
+    [Key(10)] public float[] Restitution { get; set; } = [];
+    [Key(11)] public string[] FieldIds { get; set; } = [];
+    [Key(12)] public float[] FieldPositionX { get; set; } = [];
+    [Key(13)] public float[] FieldPositionY { get; set; } = [];
+    [Key(14)] public float[] FieldStrength { get; set; } = [];
+    [Key(15)] public float[] FieldRadius { get; set; } = [];
+    [Key(16)] public float[] DirectionX { get; set; } = [];
+    [Key(17)] public float[] DirectionY { get; set; } = [];
+    [Key(18)] public float[] AngularVelocity { get; set; } = [];
+    [Key(19)] public float[] KinematicMask { get; set; } = [];
+    [Key(20)] public float[] BulletMask { get; set; } = [];
+    [Key(21)] public float[] FieldParticipationMask { get; set; } = [];
+    [Key(22)] public ulong[] CollisionCategoryBits { get; set; } = [];
+    [Key(23)] public ulong[] CollisionMaskBits { get; set; } = [];
+    [Key(24)] public int[] CollisionGroupIndex { get; set; } = [];
+
+    public static YmirWorldStateDocumentV2 FromSoA(string worldId, YmirSoAWorld world) => new()
+    {
+        WorldId = worldId, Time = world.Time,
+        BodyIds = (string[])world.BodyIds.Clone(),
+        PositionX = (float[])world.PositionX.Clone(), PositionY = (float[])world.PositionY.Clone(),
+        VelocityX = (float[])world.VelocityX.Clone(), VelocityY = (float[])world.VelocityY.Clone(),
+        Radius = (float[])world.Radius.Clone(), Mass = (float[])world.Mass.Clone(),
+        DynamicMask = (float[])world.DynamicMask.Clone(), Restitution = (float[])world.Restitution.Clone(),
+        FieldIds = (string[])world.FieldIds.Clone(),
+        FieldPositionX = (float[])world.FieldPositionX.Clone(), FieldPositionY = (float[])world.FieldPositionY.Clone(),
+        FieldStrength = (float[])world.FieldStrength.Clone(), FieldRadius = (float[])world.FieldRadius.Clone(),
+        DirectionX = (float[])world.DirectionX.Clone(), DirectionY = (float[])world.DirectionY.Clone(),
+        AngularVelocity = (float[])world.AngularVelocity.Clone(),
+        KinematicMask = (float[])world.KinematicMask.Clone(), BulletMask = (float[])world.BulletMask.Clone(),
+        FieldParticipationMask = (float[])world.FieldParticipationMask.Clone(),
+        CollisionCategoryBits = (ulong[])world.CollisionCategoryBits.Clone(),
+        CollisionMaskBits = (ulong[])world.CollisionMaskBits.Clone(),
+        CollisionGroupIndex = (int[])world.CollisionGroupIndex.Clone()
+    };
+
+    public YmirSoAWorld ToSoA() => new()
+    {
+        Time = Time, BodyIds = (string[])BodyIds.Clone(),
+        PositionX = (float[])PositionX.Clone(), PositionY = (float[])PositionY.Clone(),
+        VelocityX = (float[])VelocityX.Clone(), VelocityY = (float[])VelocityY.Clone(),
+        Radius = (float[])Radius.Clone(), Mass = (float[])Mass.Clone(),
+        DynamicMask = (float[])DynamicMask.Clone(), Restitution = (float[])Restitution.Clone(),
+        FieldIds = (string[])FieldIds.Clone(),
+        FieldPositionX = (float[])FieldPositionX.Clone(), FieldPositionY = (float[])FieldPositionY.Clone(),
+        FieldStrength = (float[])FieldStrength.Clone(), FieldRadius = (float[])FieldRadius.Clone(),
+        DirectionX = (float[])DirectionX.Clone(), DirectionY = (float[])DirectionY.Clone(),
+        AngularVelocity = (float[])AngularVelocity.Clone(),
+        KinematicMask = (float[])KinematicMask.Clone(), BulletMask = (float[])BulletMask.Clone(),
+        FieldParticipationMask = (float[])FieldParticipationMask.Clone(),
+        CollisionCategoryBits = (ulong[])CollisionCategoryBits.Clone(),
+        CollisionMaskBits = (ulong[])CollisionMaskBits.Clone(),
+        CollisionGroupIndex = (int[])CollisionGroupIndex.Clone()
+    };
+}
+
 public static class YmirCultCacheStore
 {
     public static async Task SaveWorldAsync(string path, string worldId, YmirSoAWorld world)
@@ -183,8 +253,8 @@ public static class YmirCultCacheStore
         using (cache)
         {
         await cache.UpsertAsync(
-            YmirWorldStateDocumentV1.FromSoA(worldId, world),
-            new CultRecordHandle<YmirWorldStateDocumentV1>(new CultRecordKey($"ymir:world:{worldId}")))
+            YmirWorldStateDocumentV2.FromSoA(worldId, world),
+            new CultRecordHandle<YmirWorldStateDocumentV2>(new CultRecordKey($"ymir:world:{worldId}")))
             .ConfigureAwait(false);
         await cache.FlushAsync().ConfigureAwait(false);
         }
@@ -196,7 +266,8 @@ public static class YmirCultCacheStore
             path,
             new CultCacheOpenOptions { UseDirectoryStore = true }).ConfigureAwait(false);
         var key = new CultRecordKey($"ymir:world:{worldId}");
-        return cache.Get<YmirWorldStateDocumentV1>(key)?.ToSoA()
+        return cache.Get<YmirWorldStateDocumentV2>(key)?.ToSoA()
+            ?? cache.Get<YmirWorldStateDocumentV1>(key)?.ToSoA()
             ?? cache.Get<YmirWorldStateDocumentV0>(key)?.ToSoA();
     }
 }
diff --git a/src/ymir-daemon/Program.cs b/src/ymir-daemon/Program.cs
index 54f1089..96c9e6e 100644
--- a/src/ymir-daemon/Program.cs
+++ b/src/ymir-daemon/Program.cs
@@ -82,7 +82,7 @@ internal static class Program
             ok = true,
             path,
             record = "ymir:world:sample",
-            schema = "gamecult.ymir.world_state.v1",
+            schema = "gamecult.ymir.world_state.v2",
             bodyCount = result.World.BodyCount,
             fieldCount = result.World.FieldCount
         });
diff --git a/tests/Ymir.Box3D.Parity/Box3DOracle.cs b/tests/Ymir.Box3D.Parity/Box3DOracle.cs
index 43a98be..4d42ca9 100644
--- a/tests/Ymir.Box3D.Parity/Box3DOracle.cs
+++ b/tests/Ymir.Box3D.Parity/Box3DOracle.cs
@@ -93,6 +93,18 @@ internal static partial class Box3DOracle
     [UnmanagedCallConv(CallConvs = [typeof(CallConvCdecl)])]
     internal static partial int ymir_box3d_session_get_contact_event_count(nint session);
 
+    [LibraryImport(LibraryName)]
+    [UnmanagedCallConv(CallConvs = [typeof(CallConvCdecl)])]
+    internal static partial int ymir_box3d_session_get_body_count(nint session);
+
+    [LibraryImport(LibraryName)]
+    [UnmanagedCallConv(CallConvs = [typeof(CallConvCdecl)])]
+    internal static unsafe partial int ymir_box3d_session_copy_bodies(
+        nint session,
+        Box3DSessionBodyOutput* bodies,
+        int capacity,
+        out int written);
+
     [LibraryImport(LibraryName)]
     [UnmanagedCallConv(CallConvs = [typeof(CallConvCdecl)])]
     internal static unsafe partial int ymir_box3d_session_copy_contact_events(
@@ -154,6 +166,8 @@ internal readonly record struct Box3DTorqueResult(
 [StructLayout(LayoutKind.Sequential)]
 internal readonly record struct Box3DSessionBodyInput(
     ulong StableId,
+    ulong CollisionCategoryBits,
+    ulong CollisionMaskBits,
     float PositionX,
     float PositionY,
     float VelocityX,
@@ -165,7 +179,11 @@ internal readonly record struct Box3DSessionBodyInput(
     float Radius,
     float Mass,
     float Restitution,
-    uint IsStatic);
+    uint IsStatic,
+    uint IsKinematic,
+    uint IsBullet,
+    uint ParticipatesInFields,
+    int CollisionGroupIndex);
 
 [StructLayout(LayoutKind.Sequential)]
 internal readonly record struct Box3DSessionContactEvent(
@@ -182,3 +200,14 @@ internal readonly record struct Box3DSessionContactEvent(
     float NormalY,
     float Penetration,
     float RelativeSpeed);
+
+[StructLayout(LayoutKind.Sequential)]
+internal readonly record struct Box3DSessionBodyOutput(
+    ulong StableId,
+    float PositionX,
+    float PositionY,
+    float VelocityX,
+    float VelocityY,
+    float DirectionX,
+    float DirectionY,
+    float AngularVelocity);
diff --git a/tests/Ymir.Box3D.Parity/Box3DParityTests.cs b/tests/Ymir.Box3D.Parity/Box3DParityTests.cs
index 7d68ca3..6dd9475 100644
--- a/tests/Ymir.Box3D.Parity/Box3DParityTests.cs
+++ b/tests/Ymir.Box3D.Parity/Box3DParityTests.cs
@@ -124,14 +124,12 @@ public sealed class Box3DParityTests
     [Fact]
     public unsafe void RetainedSessionCommandsPreserveTypedContactLifecycle()
     {
-        Assert.Equal(3u, Box3DOracle.ymir_box3d_get_abi_version());
+        Assert.Equal(4u, Box3DOracle.ymir_box3d_get_abi_version());
         Assert.Equal(0, Box3DOracle.ymir_box3d_session_create(out var session));
         try
         {
-            var bodyA = new Box3DSessionBodyInput(
-                1, -0.9f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0);
-            var bodyB = new Box3DSessionBodyInput(
-                2, 0.9f, 0.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0);
+            var bodyA = SessionBody(1, -0.9f);
+            var bodyB = SessionBody(2, 0.9f);
             Assert.Equal(0, Box3DOracle.ymir_box3d_session_spawn(session, &bodyA));
             Assert.Equal(0, Box3DOracle.ymir_box3d_session_spawn(session, &bodyB));
             Assert.Equal(2, Box3DOracle.ymir_box3d_session_spawn(session, &bodyA));
@@ -155,6 +153,74 @@ public sealed class Box3DParityTests
         }
     }
 
+    [Fact]
+    public unsafe void NegativeGroupAndCategoryMasksAreBox3DCollisionAuthority()
+    {
+        Assert.Equal(0, Box3DOracle.ymir_box3d_session_create(out var session));
+        try
+        {
+            var source = SessionBody(1, 0.0f, category: 1, mask: 2, group: -7);
+            var ownPayload = SessionBody(2, 0.0f, category: 2, mask: 1, group: -7);
+            var otherPayload = SessionBody(3, 0.0f, category: 2, mask: 1, group: -8);
+            Assert.Equal(0, Box3DOracle.ymir_box3d_session_spawn(session, &source));
+            Assert.Equal(0, Box3DOracle.ymir_box3d_session_spawn(session, &ownPayload));
+            Assert.Equal(0, Box3DOracle.ymir_box3d_session_spawn(session, &otherPayload));
+
+            Assert.Equal(0, Box3DOracle.ymir_box3d_session_step(session, 1.0f / 60.0f, 4, null, 0));
+            var pairs = CopyEvents(session)
+                .Where(value => value.Kind == 1)
+                .Select(value => new HashSet<ulong> { value.StableIdA, value.StableIdB })
+                .ToArray();
+
+            Assert.Single(pairs);
+            Assert.Equal(new HashSet<ulong> { 1, 3 }, pairs[0]);
+        }
+        finally
+        {
+            Box3DOracle.ymir_box3d_session_destroy(session);
+        }
+    }
+
+    [Fact]
+    public unsafe void BulletUsesBox3DContinuousCollisionAgainstKinematicTarget()
+    {
+        Assert.Equal(0, Box3DOracle.ymir_box3d_session_create(out var session));
+        try
+        {
+            var bullet = SessionBody(1, -10.0f, velocityX: 100.0f, isBullet: true);
+            var target = SessionBody(2, 0.0f, isKinematic: true);
+            Assert.Equal(0, Box3DOracle.ymir_box3d_session_spawn(session, &bullet));
+            Assert.Equal(0, Box3DOracle.ymir_box3d_session_spawn(session, &target));
+
+            Assert.Equal(0, Box3DOracle.ymir_box3d_session_step(session, 0.2f, 4, null, 0));
+            Assert.Empty(CopyEvents(session));
+            var ccdBodies = CopyBodies(session);
+            Assert.True(ccdBodies.Single(value => value.StableId == 1).PositionX < 0.0f);
+            Assert.Equal(0.0f, ccdBodies.Single(value => value.StableId == 2).PositionX, precision: 5);
+            Assert.Equal(0, Box3DOracle.ymir_box3d_session_step(session, 1.0f / 60.0f, 4, null, 0));
+            Assert.Contains(CopyEvents(session), value =>
+                (value.Kind == 1 || value.Kind == 2) &&
+                new HashSet<ulong> { value.StableIdA, value.StableIdB }.SetEquals([1UL, 2UL]));
+        }
+        finally
+        {
+            Box3DOracle.ymir_box3d_session_destroy(session);
+        }
+    }
+
+    private static Box3DSessionBodyInput SessionBody(
+        ulong id,
+        float positionX,
+        float velocityX = 0.0f,
+        ulong category = 1,
+        ulong mask = ulong.MaxValue,
+        int group = 0,
+        bool isKinematic = false,
+        bool isBullet = false) => new(
+            id, category, mask, positionX, 0.0f, velocityX, 0.0f, 0.0f, 1.0f,
+            0.0f, 0.0f, 1.0f, 1.0f, 0.0f, 0,
+            isKinematic ? 1u : 0u, isBullet ? 1u : 0u, 1u, group);
+
     private static unsafe Box3DSessionContactEvent[] CopyEvents(nint session)
     {
         var count = Box3DOracle.ymir_box3d_session_get_contact_event_count(session);
@@ -167,4 +233,17 @@ public sealed class Box3DParityTests
         }
         return events;
     }
+
+    private static unsafe Box3DSessionBodyOutput[] CopyBodies(nint session)
+    {
+        var count = Box3DOracle.ymir_box3d_session_get_body_count(session);
+        Assert.True(count >= 0);
+        var bodies = new Box3DSessionBodyOutput[count];
+        fixed (Box3DSessionBodyOutput* pointer = bodies)
+        {
+            Assert.Equal(0, Box3DOracle.ymir_box3d_session_copy_bodies(session, pointer, count, out var written));
+            Assert.Equal(count, written);
+        }
+        return bodies;
+    }
 }
diff --git a/tests/Ymir.Tests/YmirServicePublicationTests.cs b/tests/Ymir.Tests/YmirServicePublicationTests.cs
index 3668aed..b3aee04 100644
--- a/tests/Ymir.Tests/YmirServicePublicationTests.cs
+++ b/tests/Ymir.Tests/YmirServicePublicationTests.cs
@@ -24,7 +24,7 @@ public sealed class YmirServicePublicationTests
         Assert.Contains("Box3D solver and collision semantics", advertisement.DoesNotOwn);
         Assert.Equal("Box3D v0.1.0 (C17)", diagnostics.NumericSubstrate);
         Assert.Contains("does not own physics algorithms", diagnostics.BatchKernel, StringComparison.Ordinal);
-        Assert.Contains("world_state.v1", diagnostics.Persistence, StringComparison.Ordinal);
+        Assert.Contains("world_state.v2", diagnostics.Persistence, StringComparison.Ordinal);
         Assert.Contains("v0 read migration", diagnostics.Persistence, StringComparison.Ordinal);
     }
 
diff --git a/tests/Ymir.Tests/YmirSessionTests.cs b/tests/Ymir.Tests/YmirSessionTests.cs
index 662a250..ce7ad41 100644
--- a/tests/Ymir.Tests/YmirSessionTests.cs
+++ b/tests/Ymir.Tests/YmirSessionTests.cs
@@ -190,6 +190,74 @@ public sealed class YmirSessionTests
         Assert.Equal(Vec2.Zero, session.Snapshot().Bodies.Single().Velocity);
     }
 
+    [Fact]
+    public void CollisionProfilesExcludeOwnGroupAndPayloadPeers()
+    {
+        using var session = YmirSession.Create(new YmirSessionCreateRequest(
+            "collision-profile",
+            [
+                Body("source") with
+                {
+                    CollisionCategoryBits = 1,
+                    CollisionMaskBits = 2,
+                    CollisionGroupIndex = -7
+                },
+                Body("own-payload") with
+                {
+                    CollisionCategoryBits = 2,
+                    CollisionMaskBits = 1,
+                    CollisionGroupIndex = -7
+                },
+                Body("other-payload") with
+                {
+                    CollisionCategoryBits = 2,
+                    CollisionMaskBits = 1,
+                    CollisionGroupIndex = -8
+                }
+            ]));
+
+        var result = session.Step(Step("profile-step", 0, 1.0f / 60.0f));
+        var begin = Assert.Single(result.ContactFacts, fact => fact.Kind == YmirContactFactKind.Begin);
+
+        Assert.Equal(new HashSet<string> { "source", "other-payload" }, new HashSet<string> { begin.BodyA, begin.BodyB });
+    }
+
+    [Fact]
+    public void BodyCanOptOutOfRadialFields()
+    {
+        using var session = YmirSession.Create(new YmirSessionCreateRequest(
+            "field-profile",
+            [Body("affected", positionX: 1.0f), Body("ignored", positionX: -5.0f) with { ParticipatesInFields = false }]));
+
+        var result = session.Step(new YmirStepSessionCommand(
+            Header("field-step", 0),
+            0.1f,
+            [new RadialField("gravity", Vec2.Zero, 10.0f, 10.0f)]));
+
+        Assert.NotEqual(0.0f, result.World.Bodies.Single(body => body.Id == "affected").Velocity.X);
+        Assert.Equal(0.0f, result.World.Bodies.Single(body => body.Id == "ignored").Velocity.X, 5);
+    }
+
+    [Fact]
+    public void KinematicTargetDoesNotAcceptBulletImpulse()
+    {
+        using var session = YmirSession.Create(new YmirSessionCreateRequest(
+            "bullet-kinematic",
+            [
+                Body("bullet", positionX: -10.0f, velocityX: 100.0f) with { IsBullet = true },
+                Body("target") with { IsKinematic = true }
+            ]));
+
+        var ccdStep = session.Step(Step("ccd", 0, 0.2f));
+        var eventStep = session.Step(Step("event", 1, 1.0f / 60.0f));
+
+        Assert.Empty(ccdStep.ContactFacts);
+        Assert.Contains(eventStep.ContactFacts, fact => fact.Kind is YmirContactFactKind.Begin or YmirContactFactKind.Hit);
+        var target = eventStep.World.Bodies.Single(body => body.Id == "target");
+        Assert.Equal(Vec2.Zero, target.Velocity);
+        Assert.Equal(Vec2.Zero, target.Position);
+    }
+
     private static YmirCommandHeader Header(string id, long revision) => new(id, revision);
 
     private static long BodyGeneration(YmirContactFact fact, string bodyId) =>
diff --git a/tests/Ymir.Tests/YmirSimulatorTests.cs b/tests/Ymir.Tests/YmirSimulatorTests.cs
index 8eb4f05..19e2f1a 100644
--- a/tests/Ymir.Tests/YmirSimulatorTests.cs
+++ b/tests/Ymir.Tests/YmirSimulatorTests.cs
@@ -250,6 +250,46 @@ public sealed class YmirSimulatorTests
         }
     }
 
+    [Fact]
+    public async Task CultCacheV2PreservesBox3DBodyProfile()
+    {
+        var path = Path.Combine(Path.GetTempPath(), $"ymir-v2-tests-{Guid.NewGuid():N}.cc");
+        var recordsPath = $"{path}.records";
+        try
+        {
+            var world = YmirSoAWorld.FromWorld(new YmirWorld(
+                3.0f,
+                [new PhysicsBody("payload", Vec2.Zero, Vec2.Zero, 0.5f, 1.0f) with
+                {
+                    IsKinematic = true,
+                    IsBullet = true,
+                    ParticipatesInFields = false,
+                    CollisionCategoryBits = 4,
+                    CollisionMaskBits = 2,
+                    CollisionGroupIndex = -11
+                }],
+                []));
+
+            await YmirCultCacheStore.SaveWorldAsync(path, "test", world);
+            var loaded = await YmirCultCacheStore.LoadWorldAsync(path, "test");
+
+            Assert.NotNull(loaded);
+            loaded!.Validate();
+            var body = Assert.Single(loaded.ToWorld().Bodies);
+            Assert.True(body.IsKinematic);
+            Assert.True(body.IsBullet);
+            Assert.False(body.ParticipatesInFields);
+            Assert.Equal(4UL, body.CollisionCategoryBits);
+            Assert.Equal(2UL, body.CollisionMaskBits);
+            Assert.Equal(-11, body.CollisionGroupIndex);
+        }
+        finally
+        {
+            if (File.Exists(path)) File.Delete(path);
+            if (Directory.Exists(recordsPath)) Directory.Delete(recordsPath, recursive: true);
+        }
+    }
+
     private static SimulationStepResult Step(params PhysicsBody[] bodies)
     {
         var simulator = new YmirSimulator();