diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7a95530ad..419e49b61 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,9 @@ Note that since we don't clearly distinguish between a public and private interf
 - Fix empty transforms default in `ShapeFromPly`
 - Add `instanceGranularity: 'auto'` as a memory guard
 - Honor `instanceGranularity` in `Visual.getLoci`
+- Add mesoscale representation preset
+- Add presets option to `ObjectList` param definition
+- Fix memory leak in `State.dispose()` not invoking transformer `dispose` callbacks for live cells
 
 ## [v5.9.0] - 2026-05-03
 - Fix edge case when `PluginSpec.animations` is empty
diff --git a/package.json b/package.json
index 19c42d62a..39b3071e5 100644
--- a/package.json
+++ b/package.json
@@ -74,7 +74,7 @@
       "js"
     ],
     "transform": {
-      "\\.ts$": "esbuild-jest-transform"
+      "\\.ts$": ["esbuild-jest-transform", { "tsconfigRaw": "{\"compilerOptions\":{\"useDefineForClassFields\":false}}" }]
     },
     "moduleDirectories": [
       "node_modules",
diff --git a/src/apps/mesoscale-explorer/data/state.ts b/src/apps/mesoscale-explorer/data/state.ts
index 40121e4ae..db31d26cd 100644
--- a/src/apps/mesoscale-explorer/data/state.ts
+++ b/src/apps/mesoscale-explorer/data/state.ts
@@ -22,7 +22,6 @@ import { Hcl } from '../../../mol-util/color/spaces/hcl';
 import { StateObjectCell, StateObjectRef, StateSelection } from '../../../mol-state';
 import { ShapeRepresentation3D, StructureRepresentation3D } from '../../../mol-plugin-state/transforms/representation';
 import { SpacefillRepresentationProvider } from '../../../mol-repr/structure/representation/spacefill';
-import { assertUnreachable } from '../../../mol-util/type-helpers';
 import { MesoscaleExplorerState } from '../app';
 import { saturate } from '../../../mol-math/interpolate';
 import { Material } from '../../../mol-util/material';
@@ -322,38 +321,7 @@ export function getMesoscaleGroupParams(graphicsMode: GraphicsMode): MesoscaleGr
 export type LodLevels = typeof SpacefillRepresentationProvider.defaultValues['lodLevels']
 
 export function getLodLevels(graphicsMode: Exclude<GraphicsMode, 'custom'>): LodLevels {
-    switch (graphicsMode) {
-        case 'performance':
-            return [
-                { minDistance: 1, maxDistance: 300, overlap: 0, stride: 1, scaleBias: 1 },
-                { minDistance: 300, maxDistance: 2000, overlap: 0, stride: 40, scaleBias: 3 },
-                { minDistance: 2000, maxDistance: 6000, overlap: 0, stride: 150, scaleBias: 3 },
-                { minDistance: 6000, maxDistance: 10000000, overlap: 0, stride: 300, scaleBias: 2.5 },
-            ];
-        case 'balanced':
-            return [
-                { minDistance: 1, maxDistance: 500, overlap: 0, stride: 1, scaleBias: 1 },
-                { minDistance: 500, maxDistance: 2000, overlap: 0, stride: 15, scaleBias: 3 },
-                { minDistance: 2000, maxDistance: 6000, overlap: 0, stride: 70, scaleBias: 2.7 },
-                { minDistance: 6000, maxDistance: 10000000, overlap: 0, stride: 200, scaleBias: 2.5 },
-            ];
-        case 'quality':
-            return [
-                { minDistance: 1, maxDistance: 1000, overlap: 0, stride: 1, scaleBias: 1 },
-                { minDistance: 1000, maxDistance: 4000, overlap: 0, stride: 10, scaleBias: 3 },
-                { minDistance: 4000, maxDistance: 10000, overlap: 0, stride: 50, scaleBias: 2.7 },
-                { minDistance: 10000, maxDistance: 10000000, overlap: 0, stride: 200, scaleBias: 2.3 },
-            ];
-        case 'ultra':
-            return [
-                { minDistance: 1, maxDistance: 5000, overlap: 0, stride: 1, scaleBias: 1 },
-                { minDistance: 5000, maxDistance: 10000, overlap: 0, stride: 10, scaleBias: 3 },
-                { minDistance: 10000, maxDistance: 30000, overlap: 0, stride: 50, scaleBias: 2.5 },
-                { minDistance: 30000, maxDistance: 10000000, overlap: 0, stride: 200, scaleBias: 2 },
-            ];
-        default:
-            assertUnreachable(graphicsMode);
-    }
+    return Spheres.LodLevelsPresets[graphicsMode];
 }
 
 export type GraphicsMode = 'ultra' | 'quality' | 'balanced' | 'performance' | 'custom';
diff --git a/src/mol-geo/geometry/spheres/spheres.ts b/src/mol-geo/geometry/spheres/spheres.ts
index e6fb09c75..6750ee0bb 100644
--- a/src/mol-geo/geometry/spheres/spheres.ts
+++ b/src/mol-geo/geometry/spheres/spheres.ts
@@ -249,6 +249,33 @@ export namespace Spheres {
         return lodLevels.map(l => getAdjustedStride(l, sizeFactor)).reverse();
     }
 
+    export const LodLevelsPresets: { [key in 'performance' | 'balanced' | 'quality' | 'ultra']: LodLevels } = {
+        performance: [
+            { minDistance: 1, maxDistance: 300, overlap: 0, stride: 1, scaleBias: 1 },
+            { minDistance: 300, maxDistance: 2000, overlap: 0, stride: 40, scaleBias: 3 },
+            { minDistance: 2000, maxDistance: 6000, overlap: 0, stride: 150, scaleBias: 3 },
+            { minDistance: 6000, maxDistance: 10000000, overlap: 0, stride: 300, scaleBias: 2.5 },
+        ],
+        balanced: [
+            { minDistance: 1, maxDistance: 500, overlap: 0, stride: 1, scaleBias: 1 },
+            { minDistance: 500, maxDistance: 2000, overlap: 0, stride: 15, scaleBias: 3 },
+            { minDistance: 2000, maxDistance: 6000, overlap: 0, stride: 70, scaleBias: 2.7 },
+            { minDistance: 6000, maxDistance: 10000000, overlap: 0, stride: 200, scaleBias: 2.5 },
+        ],
+        quality: [
+            { minDistance: 1, maxDistance: 1000, overlap: 0, stride: 1, scaleBias: 1 },
+            { minDistance: 1000, maxDistance: 4000, overlap: 0, stride: 10, scaleBias: 3 },
+            { minDistance: 4000, maxDistance: 10000, overlap: 0, stride: 50, scaleBias: 2.7 },
+            { minDistance: 10000, maxDistance: 10000000, overlap: 0, stride: 200, scaleBias: 2.3 },
+        ],
+        ultra: [
+            { minDistance: 1, maxDistance: 5000, overlap: 0, stride: 1, scaleBias: 1 },
+            { minDistance: 5000, maxDistance: 10000, overlap: 0, stride: 10, scaleBias: 3 },
+            { minDistance: 10000, maxDistance: 30000, overlap: 0, stride: 50, scaleBias: 2.5 },
+            { minDistance: 30000, maxDistance: 10000000, overlap: 0, stride: 200, scaleBias: 2 },
+        ],
+    };
+
     export const Params = {
         ...BaseGeometry.Params,
         sizeFactor: PD.Numeric(1, { min: 0, max: 10, step: 0.1 }),
@@ -273,7 +300,8 @@ export namespace Spheres {
             scaleBias: PD.Numeric(3, { min: 0.1, max: 10, step: 0.1 }),
         }, o => `${o.stride}`, {
             ...BaseGeometry.CullingLodCategory,
-            defaultValue: [] as LodLevels
+            defaultValue: [] as LodLevels,
+            presets: Object.entries(LodLevelsPresets).map(([k, v]) => [v, k])
         })
     };
     export type Params = typeof Params
diff --git a/src/mol-plugin-state/builder/structure/representation-preset.ts b/src/mol-plugin-state/builder/structure/representation-preset.ts
index 3173c963a..8ebcd8f55 100644
--- a/src/mol-plugin-state/builder/structure/representation-preset.ts
+++ b/src/mol-plugin-state/builder/structure/representation-preset.ts
@@ -1,5 +1,5 @@
 /**
- * Copyright (c) 2019-2025 mol* contributors, licensed under MIT, See LICENSE file for more info.
+ * Copyright (c) 2019-2026 mol* contributors, licensed under MIT, See LICENSE file for more info.
  *
  * @author David Sehnal <david.sehnal@gmail.com>
  * @author Alexander Rose <alexander.rose@weirdbyte.de>
@@ -26,6 +26,7 @@ import { StructConn } from '../../../mol-model-formats/structure/property/bonds/
 import { StructureRepresentationRegistry } from '../../../mol-repr/structure/registry';
 import { assertUnreachable } from '../../../mol-util/type-helpers';
 import { Vec3 } from '../../../mol-math/linear-algebra/3d/vec3';
+import { Spheres } from '../../../mol-geo/geometry/spheres/spheres';
 
 export interface StructureRepresentationPresetProvider<P = any, S extends _Result = _Result> extends PresetProvider<PluginStateObject.Molecule.Structure, P, S> { }
 export function StructureRepresentationPresetProvider<P, S extends _Result>(repr: StructureRepresentationPresetProvider<P, S>) { return repr; }
@@ -495,6 +496,61 @@ const autoLod = StructureRepresentationPresetProvider({
     }
 });
 
+type MesoscaleGraphicsMode = keyof typeof Spheres.LodLevelsPresets
+const MesoscaleGraphicsOptions = PD.arrayToOptions(Object.keys(Spheres.LodLevelsPresets) as MesoscaleGraphicsMode[]);
+function getMesoscaleLodLevels(mode: MesoscaleGraphicsMode) {
+    return Spheres.LodLevelsPresets[mode];
+}
+
+const mesoscale = StructureRepresentationPresetProvider({
+    id: 'preset-structure-representation-mesoscale',
+    display: {
+        name: 'Mesoscale', group: 'Miscellaneous',
+        description: 'Show everything in spacefill representation with instance-granularity and level-of-detail tuned for large particle scenes.'
+    },
+    params: () => ({
+        ...CommonParams,
+        graphics: PD.Select<MesoscaleGraphicsMode>('quality', MesoscaleGraphicsOptions),
+    }),
+    async apply(ref, params, plugin) {
+        const structureCell = StateObjectRef.resolveAndCheck(plugin.state.data, ref);
+        if (!structureCell) return {};
+
+        const components = {
+            all: await presetStaticComponent(plugin, structureCell, 'all'),
+        };
+
+        const structure = structureCell.obj!.data;
+
+        const { update, builder, typeParams, color } = reprBuilder(plugin, params, structure);
+
+        const graphics: MesoscaleGraphicsMode = params.graphics ?? 'quality';
+        const lodLevels = getMesoscaleLodLevels(graphics);
+        const approximate = graphics !== 'quality' && graphics !== 'ultra';
+        const alphaThickness = graphics === 'performance' ? 15 : 12;
+
+        const representations = {
+            all: builder.buildRepresentation(update, components.all, {
+                type: 'spacefill',
+                typeParams: {
+                    ...typeParams,
+                    instanceGranularity: true,
+                    lodLevels,
+                    approximate,
+                    alphaThickness,
+                    clipPrimitive: true,
+                },
+                color: color || 'entity-id',
+            }, { tag: 'all' }),
+        };
+
+        await update.commit({ revertOnError: true });
+        await updateFocusRepr(plugin, structure, params.theme?.focus?.name ?? color, params.theme?.focus?.params);
+
+        return { components, representations };
+    }
+});
+
 export function presetStaticComponent(plugin: PluginContext, structure: StateObjectRef<PluginStateObject.Molecule.Structure>, type: StaticStructureComponentType, params?: { label?: string, tags?: string[] }) {
     return plugin.builders.structure.tryCreateComponentStatic(structure, type, params);
 }
@@ -514,5 +570,6 @@ export const PresetStructureRepresentations = {
     illustrative,
     'molecular-surface': molecularSurface,
     'auto-lod': autoLod,
+    mesoscale,
 };
 export type PresetStructureRepresentations = typeof PresetStructureRepresentations;
\ No newline at end of file
diff --git a/src/mol-plugin-ui/controls/parameters.tsx b/src/mol-plugin-ui/controls/parameters.tsx
index 4904dc26e..3c87252a7 100644
--- a/src/mol-plugin-ui/controls/parameters.tsx
+++ b/src/mol-plugin-ui/controls/parameters.tsx
@@ -1414,8 +1414,8 @@ class ObjectListItem extends React.PureComponent<ObjectListItemProps, { isExpand
     }
 }
 
-export class ObjectListControl extends React.PureComponent<ParamProps<PD.ObjectList>, { isExpanded: boolean }> {
-    state = { isExpanded: false };
+export class ObjectListControl extends React.PureComponent<ParamProps<PD.ObjectList>, { isExpanded: boolean, showPresets: boolean }> {
+    state = { isExpanded: false, showPresets: false };
 
     change(value: any) {
         this.props.onChange({ name: this.props.name, param: this.props.param, value });
@@ -1459,12 +1459,29 @@ export class ObjectListControl extends React.PureComponent<ParamProps<PD.ObjectL
         e.currentTarget.blur();
     };
 
+    toggleShowPresets = () => this.setState({ showPresets: !this.state.showPresets });
+
+    presetItems = memoizeLatest((param: PD.ObjectList) => ActionMenu.createItemsFromSelectOptions(param.presets ?? []));
+
+    onSelectPreset: ActionMenu.OnSelect = item => {
+        this.setState({ showPresets: false });
+        this.change(item?.value);
+    };
+
     render() {
         const v = this.props.value;
         const label = this.props.param.label || camelCaseToWords(this.props.name);
         const value = `${v.length} item${v.length !== 1 ? 's' : ''}`;
+        const hasPresets = !!this.props.param.presets;
+        const control = hasPresets
+            ? <div className='msp-flex-row'>
+                <button onClick={this.toggleExpanded} disabled={this.props.isDisabled}>{value}</button>
+                <IconButton svg={BookmarksOutlinedSvg} onClick={this.toggleShowPresets} toggleState={this.state.showPresets} title='Presets' disabled={this.props.isDisabled} />
+            </div>
+            : <button onClick={this.toggleExpanded} disabled={this.props.isDisabled}>{value}</button>;
         return <>
-            <ControlRow label={label} control={<button onClick={this.toggleExpanded} disabled={this.props.isDisabled}>{value}</button>} />
+            <ControlRow label={label} control={control} />
+            {hasPresets && this.state.showPresets && <ActionMenu items={this.presetItems(this.props.param)} onSelect={this.onSelectPreset} />}
             {this.state.isExpanded && <div className='msp-control-offset'>
                 {this.props.value.map((v, i) => <ObjectListItem key={i} param={this.props.param} value={v} index={i} actions={this.actions} isDisabled={this.props.isDisabled} />)}
                 <ControlGroup header='New Item'>
diff --git a/src/mol-state/_spec/state.spec.ts b/src/mol-state/_spec/state.spec.ts
new file mode 100644
index 000000000..d9a151fa0
--- /dev/null
+++ b/src/mol-state/_spec/state.spec.ts
@@ -0,0 +1,126 @@
+/**
+ * Copyright (c) 2026 mol* contributors, licensed under MIT, See LICENSE file for more info.
+ */
+
+import { State, StateObject, StateTransformer } from '../../mol-state';
+import { Task } from '../../mol-task';
+
+interface TypeInfo { name: string; typeClass: 'Root' | 'Data' }
+const Create = StateObject.factory<TypeInfo>();
+
+class Root extends Create({ name: 'Root', typeClass: 'Root' }) { }
+class Leaf extends Create<{ value: number }>({ name: 'Leaf', typeClass: 'Data' }) { }
+
+const NS = 'state-dispose-spec';
+let counter = 0;
+
+function leafTransformer(spy: () => void) {
+    return StateTransformer.create<Root, Leaf, { value: number }>(NS, {
+        name: `create-leaf-${counter++}`,
+        from: [Root],
+        to: [Leaf],
+        display: { name: 'Create Leaf' },
+        params: () => ({} as any),
+        apply({ params }) { return new Leaf({ value: params.value }); },
+        dispose() { spy(); }
+    });
+}
+
+function chainedTransformer(spy: () => void) {
+    return StateTransformer.create<Leaf, Leaf, {}>(NS, {
+        name: `chained-leaf-${counter++}`,
+        from: [Leaf],
+        to: [Leaf],
+        display: { name: 'Chained Leaf' },
+        apply({ a }) { return new Leaf({ value: a.data.value + 1 }); },
+        dispose() { spy(); }
+    });
+}
+
+function newState() {
+    return State.create(new Root({}), { runTask: <T>(t: Task<T>) => t.run() });
+}
+
+describe('State.dispose', () => {
+    it('calls transformer.dispose for every live cell', async () => {
+        const leafSpy = jest.fn();
+        const chainSpy = jest.fn();
+        const A = leafTransformer(leafSpy);
+        const B = chainedTransformer(chainSpy);
+
+        const state = newState();
+        const builder = state.build();
+        builder.toRoot<Root>().apply(A as any, { value: 1 }).apply(B as any, {});
+        await state.runTask(state.updateTree(builder));
+
+        // root + 2 transformer outputs.
+        expect(state.cells.size).toBe(3);
+
+        state.dispose();
+
+        expect(leafSpy).toHaveBeenCalledTimes(1);
+        expect(chainSpy).toHaveBeenCalledTimes(1);
+    });
+
+    it('disposes all sibling subtrees', async () => {
+        const spyA = jest.fn();
+        const spyB = jest.fn();
+        const A = leafTransformer(spyA);
+        const B = leafTransformer(spyB);
+
+        const state = newState();
+        const builder = state.build();
+        builder.toRoot<Root>().apply(A as any, { value: 1 });
+        builder.toRoot<Root>().apply(B as any, { value: 2 });
+        await state.runTask(state.updateTree(builder));
+
+        state.dispose();
+
+        expect(spyA).toHaveBeenCalledTimes(1);
+        expect(spyB).toHaveBeenCalledTimes(1);
+    });
+
+    it('does not throw when a transformer dispose throws', async () => {
+        const goodSpy = jest.fn();
+        const Throwing = StateTransformer.create<Root, Leaf, { value: number }>(NS, {
+            name: `throwing-leaf-${counter++}`,
+            from: [Root],
+            to: [Leaf],
+            display: { name: 'Throwing Leaf' },
+            apply({ params }) { return new Leaf({ value: params.value }); },
+            dispose() { throw new Error('boom'); }
+        });
+        const Good = leafTransformer(goodSpy);
+
+        const state = newState();
+        const builder = state.build();
+        builder.toRoot<Root>().apply(Throwing as any, { value: 1 });
+        builder.toRoot<Root>().apply(Good as any, { value: 2 });
+        await state.runTask(state.updateTree(builder));
+
+        const warn = jest.spyOn(console, 'warn').mockImplementation(() => {});
+        try {
+            expect(() => state.dispose()).not.toThrow();
+        } finally {
+            warn.mockRestore();
+        }
+        expect(goodSpy).toHaveBeenCalledTimes(1);
+    });
+
+    it('is a no-op for transformers without a dispose definition', async () => {
+        const NoDispose = StateTransformer.create<Root, Leaf, { value: number }>(NS, {
+            name: `no-dispose-${counter++}`,
+            from: [Root],
+            to: [Leaf],
+            display: { name: 'No-dispose Leaf' },
+            apply({ params }) { return new Leaf({ value: params.value }); }
+        });
+
+        const state = newState();
+        const builder = state.build();
+        builder.toRoot<Root>().apply(NoDispose as any, { value: 1 });
+        await state.runTask(state.updateTree(builder));
+
+        expect(() => state.dispose()).not.toThrow();
+    });
+});
diff --git a/src/mol-state/state.ts b/src/mol-state/state.ts
index 4c93c74d6..fede7bc2b 100644
--- a/src/mol-state/state.ts
+++ b/src/mol-state/state.ts
@@ -159,6 +159,23 @@ class State {
     }
 
     dispose() {
+        // Dispose every still-live cell so transformer dispose callbacks
+        // (e.g. WebGL/GL buffer cleanup) actually run. Without this,
+        // calling dispose() on a State that still has cells leaks any
+        // resources held by transformer dispose callbacks because they
+        // would only fire on per-cell deletion (see updateNode/findDeletes).
+        const refs: StateTransform.Ref[] = [];
+        StateTree.doPostOrder(this._tree, this._tree.root, { refs }, (n, _, s) => { s.refs.push(n.ref); });
+        for (let i = refs.length - 1; i >= 0; i--) {
+            const cell = (this.cells as Map<StateTransform.Ref, StateObjectCell>).get(refs[i]);
+            if (!cell) continue;
+            try {
+                dispose(cell.transform, cell.obj, cell.transform.params, cell.cache, this.globalContext);
+            } catch (e) {
+                console.warn('Error in transformer dispose during State.dispose', e);
+            }
+        }
+
         this.ev.dispose();
         this.actions.dispose();
     }
diff --git a/src/mol-util/param-definition.ts b/src/mol-util/param-definition.ts
index fa99b0585..63c939d95 100644
--- a/src/mol-util/param-definition.ts
+++ b/src/mol-util/param-definition.ts
@@ -295,10 +295,13 @@ export namespace ParamDefinition {
         type: 'object-list',
         element: Params,
         ctor(): T,
-        getLabel(t: T): string
+        getLabel(t: T): string,
+        presets?: Select<T[]>['options']
     }
-    export function ObjectList<T>(element: For<T>, getLabel: (e: T) => string, info?: Info & { defaultValue?: T[], ctor?: () => T }): ObjectList<Normalize<T>> {
-        return setInfo<ObjectList<Normalize<T>>>({ type: 'object-list', element: element as any as Params, getLabel, ctor: _defaultObjectListCtor, defaultValue: (info?.defaultValue) || [] }, info);
+    export function ObjectList<T>(element: For<T>, getLabel: (e: T) => string, info?: Info & { defaultValue?: T[], ctor?: () => T, presets?: Select<T[]>['options'] }): ObjectList<Normalize<T>> {
+        const ret = setInfo<ObjectList<Normalize<T>>>({ type: 'object-list', element: element as any as Params, getLabel, ctor: _defaultObjectListCtor, defaultValue: (info?.defaultValue) || [] }, info);
+        if (info?.presets) ret.presets = info.presets as any;
+        return ret;
     }
     function _defaultObjectListCtor(this: ObjectList) { return getDefaultValues(this.element) as any; }