diff --git a/tests/domain/build-runtime-scene.test.ts b/tests/domain/build-runtime-scene.test.ts
index a43bf0db..7545f73c 100644
--- a/tests/domain/build-runtime-scene.test.ts
+++ b/tests/domain/build-runtime-scene.test.ts
@@ -1,5 +1,5 @@
 import { describe, expect, it } from "vitest";
-import { BoxGeometry } from "three";
+import { BoxGeometry, PlaneGeometry } from "three";
 
 import { createBoxBrush } from "../../src/document/brushes";
 import { createEmptySceneDocument } from "../../src/document/scene-document";
@@ -789,6 +789,59 @@ describe("buildRuntimeSceneFromDocument", () => {
     expect(runtimeScene.sceneBounds?.max.y).toBeGreaterThanOrEqual(2);
   });
 
+  it("adds static-simple imported-model colliders as compound box pieces", () => {
+    const wallGeometry = new PlaneGeometry(4, 4, 4, 4);
+    wallGeometry.rotateY(Math.PI * 0.5);
+    const { asset, loadedAsset } = createFixtureLoadedModelAssetFromGeometry("asset-runtime-static-simple", wallGeometry);
+    const modelInstance = createModelInstance({
+      id: "model-instance-runtime-static-simple",
+      assetId: asset.id,
+      position: {
+        x: 2,
+        y: 2,
+        z: 0
+      },
+      collision: {
+        mode: "static-simple",
+        visible: true
+      }
+    });
+
+    const runtimeScene = buildRuntimeSceneFromDocument(
+      {
+        ...createEmptySceneDocument({ name: "Imported Static Simple Collider Scene" }),
+        assets: {
+          [asset.id]: asset
+        },
+        modelInstances: {
+          [modelInstance.id]: modelInstance
+        }
+      },
+      {
+        loadedModelAssets: {
+          [asset.id]: loadedAsset
+        }
+      }
+    );
+
+    expect(runtimeScene.colliders).toHaveLength(1);
+    expect(runtimeScene.colliders[0]).toMatchObject({
+      source: "modelInstance",
+      instanceId: modelInstance.id,
+      assetId: asset.id,
+      kind: "compound",
+      mode: "static-simple",
+      visible: true,
+      decomposition: "surface-voxel-boxes"
+    });
+
+    if (runtimeScene.colliders[0].source !== "modelInstance" || runtimeScene.colliders[0].kind !== "compound") {
+      throw new Error("Expected the runtime collider to be a generated compound model collider.");
+    }
+
+    expect(runtimeScene.colliders[0].pieces.every((piece) => piece.kind === "box")).toBe(true);
+  });
+
   it("preserves rotated whitebox box transforms for runner rendering and collision bounds", () => {
     const brush = createBoxBrush({
       id: "brush-rotated-room",
diff --git a/tests/domain/rapier-collision-world.test.ts b/tests/domain/rapier-collision-world.test.ts
index 7c9563f4..c7db5d23 100644
--- a/tests/domain/rapier-collision-world.test.ts
+++ b/tests/domain/rapier-collision-world.test.ts
@@ -197,6 +197,80 @@ describe("RapierCollisionWorld", () => {
     }
   });
 
+  it("blocks motion against static-simple boxified wall colliders derived from open meshes", async () => {
+    const floorBrush = createBoxBrush({
+      id: "brush-floor-static-simple-wall",
+      center: {
+        x: 0,
+        y: -0.5,
+        z: 0
+      },
+      size: {
+        x: 10,
+        y: 1,
+        z: 10
+      }
+    });
+    const wallGeometry = new PlaneGeometry(4, 4, 4, 4);
+    wallGeometry.rotateY(Math.PI * 0.5);
+    const { asset, loadedAsset } = createFixtureLoadedModelAssetFromGeometry("asset-model-static-simple-wall", wallGeometry);
+    const wallInstance = createModelInstance({
+      id: "model-instance-static-simple-wall",
+      assetId: asset.id,
+      position: {
+        x: 2,
+        y: 2,
+        z: 0
+      },
+      collision: {
+        mode: "static-simple",
+        visible: true
+      }
+    });
+    const runtimeScene = buildRuntimeSceneFromDocument(
+      {
+        ...createEmptySceneDocument({ name: "Static Simple Wall Collision Scene" }),
+        assets: {
+          [asset.id]: asset
+        },
+        brushes: {
+          [floorBrush.id]: floorBrush
+        },
+        modelInstances: {
+          [wallInstance.id]: wallInstance
+        }
+      },
+      {
+        loadedModelAssets: {
+          [asset.id]: loadedAsset
+        }
+      }
+    );
+    const collisionWorld = await RapierCollisionWorld.create(runtimeScene.colliders, runtimeScene.playerCollider);
+
+    try {
+      const blocked = collisionWorld.resolveFirstPersonMotion(
+        {
+          x: 0,
+          y: 0,
+          z: 0
+        },
+        {
+          x: 3,
+          y: 0,
+          z: 0
+        },
+        runtimeScene.playerCollider
+      );
+
+      expect(blocked.collidedAxes.x).toBe(true);
+      expect(blocked.feetPosition.x).toBeLessThan(1.8);
+      expect(blocked.feetPosition.y).toBeLessThan(0.02);
+    } finally {
+      collisionWorld.dispose();
+    }
+  });
+
   it("resolves motion against freely rotated whitebox box colliders", async () => {
     const floorBrush = createBoxBrush({
       id: "brush-floor-rotated-wall",
diff --git a/tests/geometry/model-instance-collider-generation.test.ts b/tests/geometry/model-instance-collider-generation.test.ts
index 602083e0..453f6c32 100644
--- a/tests/geometry/model-instance-collider-generation.test.ts
+++ b/tests/geometry/model-instance-collider-generation.test.ts
@@ -66,6 +66,43 @@ describe("buildGeneratedModelCollider", () => {
     expect(Array.from(collider.indices)).toSatisfy((values: number[]) => values.every(Number.isInteger));
   });
 
+  it("builds a static-simple compound collider from thin open mesh surfaces", () => {
+    const geometry = new PlaneGeometry(4, 3, 4, 3);
+    geometry.rotateY(Math.PI * 0.5);
+    const { asset, loadedAsset } = createFixtureLoadedModelAssetFromGeometry("asset-model-static-simple", geometry);
+    const modelInstance = createModelInstance({
+      id: "model-instance-static-simple",
+      assetId: asset.id,
+      collision: {
+        mode: "static-simple",
+        visible: true
+      }
+    });
+
+    const collider = buildGeneratedModelCollider(modelInstance, asset, loadedAsset);
+
+    expect(collider).not.toBeNull();
+    expect(collider).toMatchObject({
+      kind: "compound",
+      mode: "static-simple",
+      decomposition: "surface-voxel-boxes",
+      runtimeBehavior: "fixedQueryOnly"
+    });
+
+    if (collider === null || collider.kind !== "compound") {
+      throw new Error("Expected a compound collider.");
+    }
+
+    expect(collider.pieces.length).toBeGreaterThanOrEqual(1);
+    expect(collider.pieces.every((piece) => piece.kind === "box")).toBe(true);
+
+    if (collider.pieces[0]?.kind !== "box") {
+      throw new Error("Expected the first static-simple collider piece to be a box.");
+    }
+
+    expect(collider.pieces[0].size.x).toBeGreaterThan(0.01);
+  });
+
   it("builds a terrain heightfield from a regular-grid mesh", () => {
     const geometry = new PlaneGeometry(4, 4, 2, 2);
     geometry.rotateX(-Math.PI * 0.5);
diff --git a/tests/serialization/scene-document-json.test.ts b/tests/serialization/scene-document-json.test.ts
index ebcbbc4c..dd77b0c5 100644
--- a/tests/serialization/scene-document-json.test.ts
+++ b/tests/serialization/scene-document-json.test.ts
@@ -12,6 +12,7 @@ import {
   PLAYER_START_COLLIDER_SETTINGS_SCENE_DOCUMENT_VERSION,
   PLAYER_START_INPUT_BINDINGS_SCENE_DOCUMENT_VERSION,
   PLAYER_START_NAVIGATION_MODE_SCENE_DOCUMENT_VERSION,
+  SCENE_EDITOR_PREFERENCES_SCENE_DOCUMENT_VERSION,
   SCENE_TRANSITION_ENTITIES_SCENE_DOCUMENT_VERSION,
   SCENE_DOCUMENT_VERSION,
   SPATIAL_AUDIO_SCENE_DOCUMENT_VERSION,
@@ -1032,6 +1033,130 @@ describe("scene document JSON", () => {
     expect(parseSceneDocumentJson(serializeSceneDocument(document))).toEqual(document);
   });
 
+  it("round-trips authored static-simple model-instance collision settings", () => {
+    const asset = {
+      id: "asset-model-static-simple-collider",
+      kind: "model",
+      sourceName: "collision-static-simple.glb",
+      mimeType: "model/gltf-binary",
+      storageKey: createProjectAssetStorageKey("asset-model-static-simple-collider"),
+      byteLength: 64,
+      metadata: {
+        kind: "model",
+        format: "glb",
+        sceneName: "Static Simple Collision Test Scene",
+        nodeCount: 1,
+        meshCount: 1,
+        materialNames: [],
+        textureNames: [],
+        animationNames: [],
+        boundingBox: {
+          min: {
+            x: -2,
+            y: 0,
+            z: -0.1
+          },
+          max: {
+            x: 2,
+            y: 4,
+            z: 0.1
+          },
+          size: {
+            x: 4,
+            y: 4,
+            z: 0.2
+          }
+        },
+        warnings: []
+      }
+    } satisfies ModelAssetRecord;
+    const modelInstance = createModelInstance({
+      id: "model-instance-static-simple-collider",
+      assetId: asset.id,
+      collision: {
+        mode: "static-simple",
+        visible: true
+      }
+    });
+    const document = {
+      ...createEmptySceneDocument({ name: "Static Simple Model Collision Scene" }),
+      assets: {
+        [asset.id]: asset
+      },
+      modelInstances: {
+        [modelInstance.id]: modelInstance
+      }
+    };
+
+    expect(parseSceneDocumentJson(serializeSceneDocument(document))).toEqual(document);
+  });
+
+  it("migrates version 29 scene documents to preserve existing model collision settings", () => {
+    const asset = {
+      id: "asset-model-v29-collider",
+      kind: "model",
+      sourceName: "v29-collider.glb",
+      mimeType: "model/gltf-binary",
+      storageKey: createProjectAssetStorageKey("asset-model-v29-collider"),
+      byteLength: 64,
+      metadata: {
+        kind: "model",
+        format: "glb",
+        sceneName: "V29 Collider 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 legacyDocument = {
+      ...createEmptySceneDocument({ name: "Legacy V29 Collider Scene" }),
+      version: SCENE_EDITOR_PREFERENCES_SCENE_DOCUMENT_VERSION,
+      assets: {
+        [asset.id]: asset
+      },
+      modelInstances: {
+        "model-instance-v29-collider": {
+          ...createModelInstance({
+            id: "model-instance-v29-collider",
+            assetId: asset.id,
+            collision: {
+              mode: "dynamic",
+              visible: true
+            }
+          })
+        }
+      }
+    };
+
+    const migratedDocument = migrateSceneDocument(legacyDocument);
+
+    expect(migratedDocument.version).toBe(SCENE_DOCUMENT_VERSION);
+    expect(migratedDocument.modelInstances["model-instance-v29-collider"].collision).toEqual({
+      mode: "dynamic",
+      visible: true
+    });
+  });
+
   it("round-trips canonical interaction links", () => {
     const triggerVolume = createTriggerVolumeEntity({
       id: "entity-trigger-main"