diff --git a/src/document/migrate-scene-document.ts b/src/document/migrate-scene-document.ts
index 5d3a826b..59b8a340 100644
--- a/src/document/migrate-scene-document.ts
+++ b/src/document/migrate-scene-document.ts
@@ -1489,7 +1489,7 @@ export function migrateSceneDocument(source: unknown): SceneDocument {
     const assets = readAssets(source.assets);
 
     return {
-      version: ENTITY_NAMES_SCENE_DOCUMENT_VERSION,
+      version: SCENE_DOCUMENT_VERSION,
       name: expectString(source.name, "name"),
       world: readWorldSettings(source.world),
       materials,
diff --git a/src/geometry/model-instance-collider-generation.ts b/src/geometry/model-instance-collider-generation.ts
index f6d64c71..e29ebd86 100644
--- a/src/geometry/model-instance-collider-generation.ts
+++ b/src/geometry/model-instance-collider-generation.ts
@@ -6,7 +6,6 @@ import {
   Mesh,
   Quaternion,
   Vector3,
-  type BufferAttribute,
   type BufferGeometry
 } from "three";
 
@@ -206,7 +205,13 @@ function computeWorldBoundsFromLocalBox(localBounds: GeneratedColliderBounds, mo
   return computeBoundsFromPoints(corners.map((corner) => corner.applyMatrix4(modelMatrix)));
 }
 
-function readIndexedVertex(position: BufferAttribute, index: number, matrix: Matrix4): Vector3 {
+interface PositionLikeAttribute {
+  getX(index: number): number;
+  getY(index: number): number;
+  getZ(index: number): number;
+}
+
+function readIndexedVertex(position: PositionLikeAttribute, index: number, matrix: Matrix4): Vector3 {
   return new Vector3(position.getX(index), position.getY(index), position.getZ(index)).applyMatrix4(matrix);
 }
 
diff --git a/src/runtime-three/rapier-collision-world.ts b/src/runtime-three/rapier-collision-world.ts
index a4e4ef74..db68e6d0 100644
--- a/src/runtime-three/rapier-collision-world.ts
+++ b/src/runtime-three/rapier-collision-world.ts
@@ -1,5 +1,5 @@
 import RAPIER from "@dimforge/rapier3d-compat";
-import { Euler, MathUtils, Quaternion, Vector3 } from "three";
+import { Euler, MathUtils, Quaternion } from "three";
 
 import type { Vec3 } from "../core/vector";
 import type {
@@ -18,14 +18,6 @@ const COLLISION_EPSILON = 1e-5;
 
 let rapierInitPromise: Promise<typeof RAPIER> | null = null;
 
-function cloneVec3(vector: Vec3): Vec3 {
-  return {
-    x: vector.x,
-    y: vector.y,
-    z: vector.z
-  };
-}
-
 function componentScale(vector: Vec3, scale: Vec3): Vec3 {
   return {
     x: vector.x * scale.x,
diff --git a/src/runtime-three/runtime-host.ts b/src/runtime-three/runtime-host.ts
index edeef583..7ac06bd4 100644
--- a/src/runtime-three/runtime-host.ts
+++ b/src/runtime-three/runtime-host.ts
@@ -510,7 +510,11 @@ export class RuntimeHost {
           name: modelInstance.name,
           position: modelInstance.position,
           rotationDegrees: modelInstance.rotationDegrees,
-          scale: modelInstance.scale
+          scale: modelInstance.scale,
+          collision: {
+            mode: "none",
+            visible: false
+          }
         },
         asset,
         loadedAsset,
diff --git a/tests/domain/build-runtime-scene.test.ts b/tests/domain/build-runtime-scene.test.ts
index c0ff5c1e..49cc2fa9 100644
--- a/tests/domain/build-runtime-scene.test.ts
+++ b/tests/domain/build-runtime-scene.test.ts
@@ -1,4 +1,5 @@
 import { describe, expect, it } from "vitest";
+import { BoxGeometry } from "three";
 
 import { createBoxBrush } from "../../src/document/brushes";
 import { createEmptySceneDocument } from "../../src/document/scene-document";
@@ -15,6 +16,7 @@ import { createTeleportPlayerInteractionLink, createToggleVisibilityInteractionL
 import { createModelInstance } from "../../src/assets/model-instances";
 import { createProjectAssetStorageKey, type AudioAssetRecord } from "../../src/assets/project-assets";
 import { buildRuntimeSceneFromDocument } from "../../src/runtime-three/runtime-scene-build";
+import { createFixtureLoadedModelAssetFromGeometry } from "../helpers/model-collider-fixtures";
 
 describe("buildRuntimeSceneFromDocument", () => {
   it("builds runtime brush data, colliders, and an authored player spawn from the document", () => {
@@ -286,6 +288,7 @@ describe("buildRuntimeSceneFromDocument", () => {
     expect(runtimeScene.colliders).toEqual([
       {
         kind: "box",
+        source: "brush",
         brushId: "brush-room-floor",
         min: {
           x: -4,
@@ -526,4 +529,65 @@ describe("buildRuntimeSceneFromDocument", () => {
       })
     ).toThrow("First-person run requires an authored Player Start");
   });
+
+  it("adds generated imported-model colliders to the runtime scene build", () => {
+    const floorBrush = createBoxBrush({
+      id: "brush-runtime-floor",
+      center: {
+        x: 0,
+        y: -0.5,
+        z: 0
+      },
+      size: {
+        x: 8,
+        y: 1,
+        z: 8
+      }
+    });
+    const { asset, loadedAsset } = createFixtureLoadedModelAssetFromGeometry("asset-runtime-collider", new BoxGeometry(1, 2, 1));
+    const modelInstance = createModelInstance({
+      id: "model-instance-runtime-collider",
+      assetId: asset.id,
+      position: {
+        x: 2,
+        y: 1,
+        z: 0
+      },
+      collision: {
+        mode: "static",
+        visible: true
+      }
+    });
+
+    const runtimeScene = buildRuntimeSceneFromDocument(
+      {
+        ...createEmptySceneDocument({ name: "Imported Collider Scene" }),
+        assets: {
+          [asset.id]: asset
+        },
+        brushes: {
+          [floorBrush.id]: floorBrush
+        },
+        modelInstances: {
+          [modelInstance.id]: modelInstance
+        }
+      },
+      {
+        loadedModelAssets: {
+          [asset.id]: loadedAsset
+        }
+      }
+    );
+
+    expect(runtimeScene.colliders).toHaveLength(2);
+    expect(runtimeScene.colliders[1]).toMatchObject({
+      source: "modelInstance",
+      instanceId: modelInstance.id,
+      assetId: asset.id,
+      kind: "trimesh",
+      mode: "static",
+      visible: true
+    });
+    expect(runtimeScene.sceneBounds?.max.y).toBeGreaterThanOrEqual(2);
+  });
 });
diff --git a/tests/serialization/scene-document-json.test.ts b/tests/serialization/scene-document-json.test.ts
index bf9dae9f..659002db 100644
--- a/tests/serialization/scene-document-json.test.ts
+++ b/tests/serialization/scene-document-json.test.ts
@@ -585,6 +585,64 @@ describe("scene document JSON", () => {
     expect(parseSceneDocumentJson(serializeSceneDocument(document))).toEqual(document);
   });
 
+  it("round-trips authored model-instance collision settings", () => {
+    const asset = {
+      id: "asset-model-collider",
+      kind: "model",
+      sourceName: "collision-test.glb",
+      mimeType: "model/gltf-binary",
+      storageKey: createProjectAssetStorageKey("asset-model-collider"),
+      byteLength: 64,
+      metadata: {
+        kind: "model",
+        format: "glb",
+        sceneName: "Collision Test Scene",
+        nodeCount: 1,
+        meshCount: 1,
+        materialNames: [],
+        textureNames: [],
+        animationNames: [],
+        boundingBox: {
+          min: {
+            x: -1,
+            y: 0,
+            z: -1
+          },
+          max: {
+            x: 1,
+            y: 2,
+            z: 1
+          },
+          size: {
+            x: 2,
+            y: 2,
+            z: 2
+          }
+        },
+        warnings: []
+      }
+    } satisfies ModelAssetRecord;
+    const modelInstance = createModelInstance({
+      id: "model-instance-collider",
+      assetId: asset.id,
+      collision: {
+        mode: "dynamic",
+        visible: true
+      }
+    });
+    const document = {
+      ...createEmptySceneDocument({ name: "Model Collision Scene" }),
+      assets: {
+        [asset.id]: asset
+      },
+      modelInstances: {
+        [modelInstance.id]: modelInstance
+      }
+    };
+
+    expect(parseSceneDocumentJson(serializeSceneDocument(document))).toEqual(document);
+  });
+
   it("round-trips canonical interaction links", () => {
     const triggerVolume = createTriggerVolumeEntity({
       id: "entity-trigger-main"