diff --git a/packages/json-joy/package.json b/packages/json-joy/package.json
index 5bccb2bb9e..4d9f38668b 100644
--- a/packages/json-joy/package.json
+++ b/packages/json-joy/package.json
@@ -92,9 +92,8 @@
     "very-small-parser": "^1.14.0"
   },
   "devDependencies": {
-    "@monaco-editor/react": "^4.7.0",
+    "@jsonjoy.com/json-random": "workspace:*",
     "@radix-ui/react-icons": "^1.3.1",
-    "@types/node": "^24.8.1",
     "@types/react": "^18.3.11",
     "@types/react-dom": "^18.3.0",
     "clipboard-copy": "^4.0.1",
@@ -108,7 +107,6 @@
     "jest": "^29.7.0",
     "json-crdt-traces": "https://github.com/streamich/json-crdt-traces#ec825401dc05cbb74b9e0b3c4d6527399f54d54d",
     "json-logic-js": "^2.0.2",
-    "monaco-editor": "^0.54.0",
     "nano-theme": "^1.4.3",
     "nice-ui": "^1.30.0",
     "prosemirror-model": "^1.25.1",
diff --git a/packages/json-joy/src/json-crdt-extensions/ModelWithExt.ts b/packages/json-joy/src/json-crdt-extensions/ModelWithExt.ts
index 873da8520c..0ce0392347 100644
--- a/packages/json-joy/src/json-crdt-extensions/ModelWithExt.ts
+++ b/packages/json-joy/src/json-crdt-extensions/ModelWithExt.ts
@@ -11,6 +11,7 @@ extensions.register(ext.cnt);
 extensions.register(ext.mval);
 extensions.register(ext.peritext);
 extensions.register(ext.quill);
+extensions.register(ext.prosemirror);
 
 export {ext};
 
@@ -31,7 +32,7 @@ export class ModelWithExt {
     sid?: number,
     schema?: S,
   ): Model<SchemaToJsonNode<S>> => {
-    const model = Model.load(data, sid, schema);
+    const model = Model.load<S>(data, sid, schema);
     model.ext = extensions;
     return model;
   };
diff --git a/packages/json-joy/src/json-crdt-extensions/constants.ts b/packages/json-joy/src/json-crdt-extensions/constants.ts
index b15b20115b..c0f4b029ec 100644
--- a/packages/json-joy/src/json-crdt-extensions/constants.ts
+++ b/packages/json-joy/src/json-crdt-extensions/constants.ts
@@ -3,6 +3,7 @@ export enum ExtensionId {
   cnt = 1,
   peritext = 2,
   quill = 3,
+  prosemirror = 4,
 }
 
 export enum ExtensionName {
@@ -10,4 +11,5 @@ export enum ExtensionName {
   cnt = ExtensionId.cnt,
   peritext = ExtensionId.peritext,
   quill = ExtensionId.quill,
+  prosemirror = ExtensionId.prosemirror,
 }
diff --git a/packages/json-joy/src/json-crdt-extensions/ext.ts b/packages/json-joy/src/json-crdt-extensions/ext.ts
index 97d167d4d3..35abd951ff 100644
--- a/packages/json-joy/src/json-crdt-extensions/ext.ts
+++ b/packages/json-joy/src/json-crdt-extensions/ext.ts
@@ -2,5 +2,6 @@ import {cnt} from './cnt';
 import {mval} from './mval';
 import {peritext} from './peritext';
 import {quill} from './quill-delta';
+import {prosemirror} from './prosemirror';
 
-export {cnt, mval, peritext, quill};
+export {cnt, mval, peritext, quill, prosemirror};
diff --git a/packages/json-joy/src/json-crdt-extensions/index.ts b/packages/json-joy/src/json-crdt-extensions/index.ts
index 0189fd7774..30614033b6 100644
--- a/packages/json-joy/src/json-crdt-extensions/index.ts
+++ b/packages/json-joy/src/json-crdt-extensions/index.ts
@@ -2,6 +2,7 @@ export * from './mval';
 export * from './cnt';
 export * from './peritext';
 export * from './quill-delta';
+export * from './prosemirror';
 export * from './ext';
 export * from './ModelWithExt';
 export * from './constants';
diff --git a/packages/json-joy/src/json-crdt-extensions/prosemirror/FromPm.ts b/packages/json-joy/src/json-crdt-extensions/prosemirror/FromPm.ts
new file mode 100644
index 0000000000..458ca6b0c4
--- /dev/null
+++ b/packages/json-joy/src/json-crdt-extensions/prosemirror/FromPm.ts
@@ -0,0 +1,94 @@
+import {Anchor} from '../peritext/rga/constants';
+import {SliceHeaderShift, SliceStacking} from '../peritext/slice/constants';
+import type {ViewRange, ViewSlice} from '../peritext/editor/types';
+import type {PmFragment, PmNode, PmTextNode} from './types';
+import type {SliceTypeStep, SliceTypeSteps} from '../peritext';
+
+/**
+ * Converts ProseMirror raw nodes to a {@link ViewRange} flat string with
+ * annotation ranges, which is the natural view format for a Peritext model.
+ *
+ * Usage:
+ *
+ * ```typescript
+ * FromPm.convert(node);
+ * ```
+ */
+export class FromPm {
+  static readonly convert = (node: PmNode): ViewRange => new FromPm().convert(node);
+
+  private text = '';
+  private slices: ViewSlice[] = [];
+
+  private conv(node: PmNode, path: SliceTypeSteps, nodeDiscriminator: number): void {
+    const text = this.text;
+    const start = text.length;
+    let inlineText: string = '';
+    const type = node.type.name;
+    if (type === 'text' && (inlineText = (node as PmTextNode).text || '')) {
+      this.text += inlineText;
+    } else {
+      const content = node.content?.content;
+      const data = node.attrs;
+      const step: SliceTypeStep = nodeDiscriminator || data ? [type, nodeDiscriminator, data] : type;
+      const length = content?.length ?? 0;
+      const hasNoChildren = length === 0;
+      const isFirstChildInline = content?.[0]?.type.name === 'text';
+      const doEmitSplitMarker = hasNoChildren || isFirstChildInline;
+      if (doEmitSplitMarker) {
+        this.text += '\n';
+        const header =
+          (SliceStacking.Marker << SliceHeaderShift.Stacking) +
+          (Anchor.Before << SliceHeaderShift.X1Anchor) +
+          (Anchor.Before << SliceHeaderShift.X2Anchor);
+        const slice: ViewSlice = [header, start, start, [...path, step]];
+        this.slices.push(slice);
+      }
+      if (length > 0) this.cont([...path, step], content!);
+    }
+    const marks = node.marks;
+    let length = 0;
+    if (marks && (length = marks.length) > 0) {
+      const end = start + inlineText.length;
+      for (let i = 0; i < length; i++) {
+        const mark = marks[i];
+        const type = mark.type.name;
+        const data = mark.attrs;
+        let dataEmpty = true;
+        for (const _ in data) {
+          dataEmpty = false;
+          break;
+        }
+        const stacking: SliceStacking = dataEmpty ? SliceStacking.One : SliceStacking.Many;
+        const header =
+          (stacking << SliceHeaderShift.Stacking) +
+          (Anchor.Before << SliceHeaderShift.X1Anchor) +
+          (Anchor.After << SliceHeaderShift.X2Anchor);
+        const slice: ViewSlice = [header, start, end, type];
+        if (!dataEmpty) slice.push(data);
+        this.slices.push(slice);
+      }
+    }
+  }
+
+  private cont(path: SliceTypeSteps, content: PmFragment['content']): void {
+    let prevTag: string = '';
+    let discriminator: number = 0;
+    const length = content.length;
+    for (let i = 0; i < length; i++) {
+      const child = content[i];
+      const tag = child.type.name;
+      discriminator = tag === prevTag ? discriminator + 1 : 0;
+      this.conv(child, path, discriminator);
+      prevTag = tag;
+    }
+  }
+
+  public convert(node: PmNode): ViewRange {
+    const content = node.content?.content;
+    let length = 0;
+    if (content && (length = content.length) > 0) this.cont([], content);
+    const view: ViewRange = [this.text, 0, this.slices];
+    return view;
+  }
+}
diff --git a/packages/json-joy/src/json-crdt-extensions/prosemirror/ProseMirrorApi.ts b/packages/json-joy/src/json-crdt-extensions/prosemirror/ProseMirrorApi.ts
new file mode 100644
index 0000000000..ce43d1a4fb
--- /dev/null
+++ b/packages/json-joy/src/json-crdt-extensions/prosemirror/ProseMirrorApi.ts
@@ -0,0 +1,23 @@
+import {NodeApi} from '../../json-crdt/model/api/nodes';
+import {FromPm} from './FromPm';
+import type {ProseMirrorNode} from './ProseMirrorNode';
+import type {ArrApi, ArrNode, ExtApi, StrApi} from '../../json-crdt';
+import type {SliceNode} from '../peritext/slice/types';
+import type {PmNode} from './types';
+
+export class ProseMirrorApi extends NodeApi<ProseMirrorNode> implements ExtApi<ProseMirrorNode> {
+  public text(): StrApi {
+    return this.api.wrap(this.node.text());
+  }
+
+  public slices(): ArrApi<ArrNode<SliceNode>> {
+    return this.api.wrap(this.node.slices());
+  }
+
+  public mergePmNode(node: PmNode) {
+    const txt = this.node.txt;
+    // TODO: to speed up convert directly to .merge() internal format.
+    const viewRange = FromPm.convert(node);
+    txt.editor.merge(viewRange);
+  }
+}
diff --git a/packages/json-joy/src/json-crdt-extensions/prosemirror/ProseMirrorNode.ts b/packages/json-joy/src/json-crdt-extensions/prosemirror/ProseMirrorNode.ts
new file mode 100644
index 0000000000..94f0bf0db3
--- /dev/null
+++ b/packages/json-joy/src/json-crdt-extensions/prosemirror/ProseMirrorNode.ts
@@ -0,0 +1,95 @@
+import {type Block, type Inline, LeafBlock, Peritext} from '../peritext';
+import {ExtensionId} from '../constants';
+import {MNEMONIC} from './constants';
+import {ExtNode} from '../../json-crdt/extensions/ExtNode';
+import {Slice} from '../peritext/slice/Slice';
+import type {StrNode} from '../../json-crdt/nodes/str/StrNode';
+import type {ArrNode} from '../../json-crdt/nodes/arr/ArrNode';
+import type {PmAttrs, PmDataNode, PmJsonMark, PmJsonNode, PmJsonTextNode} from './types';
+
+export class ProseMirrorNode extends ExtNode<PmDataNode> {
+  public readonly txt: Peritext<string>;
+
+  constructor(public readonly data: PmDataNode) {
+    super(data);
+    this.txt = new Peritext<string>(data.doc, this.text(), this.slices());
+  }
+
+  public text(): StrNode<string> {
+    return this.data.get(0)!;
+  }
+
+  public slices(): ArrNode {
+    return this.data.get(1)!;
+  }
+
+  // ------------------------------------------------------------------ ExtNode
+  public readonly extId = ExtensionId.prosemirror;
+
+  public name(): string {
+    return MNEMONIC;
+  }
+
+  private _view: PmJsonNode | null = null;
+  private _viewHash: number = -1;
+
+  private toPM(block: Block | LeafBlock): PmJsonNode {
+    const content: PmJsonNode['content'] = [];
+    const node: PmJsonNode = {type: block.tag() + ''};
+    if (block instanceof LeafBlock) {
+      for (let iterator = block.texts0(), inline: Inline | undefined; (inline = iterator()); ) {
+        const text = inline.text();
+        if (!text) continue;
+        const textNode: PmJsonTextNode = {
+          type: 'text',
+          text,
+        };
+        const slices = inline.p1.layers;
+        const length = slices.length;
+        if (length > 0) {
+          const marks: PmJsonMark[] = [];
+          for (let i = 0; i < length; i++) {
+            const slice = slices[i];
+            if (slice instanceof Slice) {
+              const tag = slice.type() + '';
+              const data = slice.data();
+              const mark: PmJsonMark = {type: tag};
+              if (data && typeof data === 'object' && !Array.isArray(data)) mark.attrs = data as PmAttrs;
+              marks.push(mark);
+            }
+          }
+          textNode.marks = marks;
+        }
+        content.push(textNode);
+      }
+    } else {
+      const children = block.children;
+      const length = children.length;
+      for (let i = 0; i < length; i++) content.push(this.toPM(children[i]));
+    }
+    if (content.length) node.content = content;
+    const data = block.attr();
+    if (data && typeof data === 'object') {
+      for (const _ in data) {
+        node.attrs = data as PmAttrs;
+        break;
+      }
+    }
+    return node;
+  }
+
+  public view(): PmJsonNode {
+    const {txt} = this;
+    const hash = txt.refresh();
+    if (this._view && hash === this._viewHash) return this._view;
+    const content: PmJsonNode[] = [];
+    const node: PmJsonNode = {type: 'doc', content};
+    const block = txt.blocks.root;
+    const children = block.children;
+    const length = children.length;
+    for (let i = 0; i < length; i++) content.push(this.toPM(children[i]));
+    this._viewHash = hash;
+    this._view = node;
+    return node;
+  }
+}
diff --git a/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/FromPm.automated.spec.ts b/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/FromPm.automated.spec.ts
new file mode 100644
index 0000000000..9cb41c2944
--- /dev/null
+++ b/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/FromPm.automated.spec.ts
@@ -0,0 +1,8 @@
+import * as fixtures from './fixtures';
+import {assertCanConvert} from './setup';
+
+for (const [name, fixture] of Object.entries(fixtures)) {
+  test(name, () => {
+    assertCanConvert(fixture);
+  });
+}
diff --git a/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/FromPm.fuzzer.spec.ts b/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/FromPm.fuzzer.spec.ts
new file mode 100644
index 0000000000..346ef77f30
--- /dev/null
+++ b/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/FromPm.fuzzer.spec.ts
@@ -0,0 +1,10 @@
+import {assertCanConvert} from './setup';
+import {NodeToViewRangeFuzzer} from './fuzzer';
+
+test('fuzzer', () => {
+  for (let i = 0; i < 100; i++) {
+    const doc = NodeToViewRangeFuzzer.doc();
+    assertCanConvert(doc);
+    assertCanConvert(doc);
+  }
+});
diff --git a/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/FromPm.spec.ts b/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/FromPm.spec.ts
new file mode 100644
index 0000000000..a137fc3344
--- /dev/null
+++ b/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/FromPm.spec.ts
@@ -0,0 +1,213 @@
+import {s} from '../../../json-crdt-patch';
+import {ModelWithExt as Model, ext} from '../../ModelWithExt';
+import {FromPm} from '../FromPm';
+import {Node} from 'prosemirror-model';
+import {schema, doc, blockquote, p, em, strong, eq, h2, h1} from 'prosemirror-test-builder';
+import {fuzzer1} from './fixtures';
+
+describe('FromPm', () => {
+  describe('convert()', () => {
+    test('single text paragraph', () => {
+      const node = doc(p('hello')) as Node;
+      const viewRange = FromPm.convert(node);
+      const model = Model.create(
+        s.obj({
+          prose: ext.prosemirror.new(''),
+        }),
+      );
+      const prosemirror = model.s.prose.toExt();
+      prosemirror.node.txt.editor.import(0, viewRange);
+      const view = prosemirror.view();
+      expect(view).toEqual(node.toJSON());
+    });
+
+    test('single text paragraph with a single inline formatting', () => {
+      const node = doc(p('Text: ', strong('bold'), '!')) as Node;
+      const viewRange = FromPm.convert(node);
+      const model = Model.create(ext.prosemirror.new());
+      const prosemirror = model.s.toExt();
+      prosemirror.node.txt.editor.import(0, viewRange);
+      prosemirror.node.txt.refresh();
+      const view = prosemirror.view();
+      expect(view).toEqual(node.toJSON());
+    });
+
+    test('single text paragraph wrapped in inline formatting', () => {
+      const node = doc(p(strong('bold'))) as Node;
+      const viewRange = FromPm.convert(node);
+      const model = Model.create(ext.prosemirror.new());
+      const prosemirror = model.s.toExt();
+      prosemirror.node.txt.editor.import(0, viewRange);
+      prosemirror.node.txt.refresh();
+      const view = prosemirror.view();
+      expect(view).toEqual(node.toJSON());
+    });
+
+    test('<strong> inside <em>', () => {
+      const node = doc(p(em(strong('bold')))) as Node;
+      const viewRange = FromPm.convert(node);
+      const model = Model.create(ext.prosemirror.new());
+      const prosemirror = model.s.toExt();
+      prosemirror.node.txt.editor.import(0, viewRange);
+      prosemirror.node.txt.refresh();
+      const view = prosemirror.view();
+      expect(view).toEqual(node.toJSON());
+      const node2 = Node.fromJSON(schema, view);
+      expect(view).toEqual(node2.toJSON());
+    });
+
+    test('<em> inside <strong>', () => {
+      const node = doc(p(strong(em('bold')))) as Node;
+      const viewRange = FromPm.convert(node);
+      const model = Model.create(ext.prosemirror.new());
+      const prosemirror = model.s.toExt();
+      prosemirror.node.txt.editor.import(0, viewRange);
+      prosemirror.node.txt.refresh();
+      const view = prosemirror.view();
+      expect(view).toEqual(node.toJSON());
+      const node2 = Node.fromJSON(schema, view);
+      expect(view).toEqual(node2.toJSON());
+    });
+
+    test('two <paragraph>', () => {
+      const node = doc(p('paragraph 1'), p('paragraph 2')) as Node;
+      const viewRange = FromPm.convert(node);
+      const model = Model.create(ext.prosemirror.new());
+      const prosemirror = model.s.toExt();
+      prosemirror.node.txt.editor.import(0, viewRange);
+      prosemirror.node.txt.refresh();
+      const view = prosemirror.view();
+      expect(view).toEqual(node.toJSON());
+    });
+
+    test('<paragraph> and <blockquote>', () => {
+      const node = doc(p('paragraph 1'), blockquote('blockquote 2')) as Node;
+      const viewRange = FromPm.convert(node);
+      const model = Model.create(ext.prosemirror.new());
+      const prosemirror = model.s.toExt();
+      prosemirror.node.txt.editor.import(0, viewRange);
+      prosemirror.node.txt.refresh();
+      const view = prosemirror.view();
+      expect(view).toEqual(node.toJSON());
+    });
+
+    test('two <paragraph> in <blockquote>', () => {
+      const node = doc(blockquote(p('paragraph 1'), p('paragraph 2'))) as Node;
+      const viewRange = FromPm.convert(node);
+      const model = Model.create(ext.prosemirror.new());
+      const prosemirror = model.s.toExt();
+      prosemirror.node.txt.editor.import(0, viewRange);
+      prosemirror.node.txt.refresh();
+      const view = prosemirror.view();
+      expect(view).toEqual(node.toJSON());
+    });
+
+    test('two <blockquote> with <paragraph> each', () => {
+      const node = doc(blockquote(p('paragraph 1')), blockquote(p('paragraph 2'))) as Node;
+      const viewRange = FromPm.convert(node);
+      const model = Model.create(ext.prosemirror.new());
+      const prosemirror = model.s.toExt();
+      prosemirror.node.txt.editor.import(0, viewRange);
+      prosemirror.node.txt.refresh();
+      const view = prosemirror.view();
+      expect(view).toEqual(node.toJSON());
+    });
+
+    test('three <blockquote> with <paragraph> each', () => {
+      const node = doc(
+        blockquote(p('paragraph 1')),
+        blockquote(p('paragraph 2')),
+        blockquote(p('paragraph 3')),
+      ) as Node;
+      const viewRange = FromPm.convert(node);
+      const model = Model.create(ext.prosemirror.new());
+      const prosemirror = model.s.toExt();
+      prosemirror.node.txt.editor.import(0, viewRange);
+      prosemirror.node.txt.refresh();
+      const view = prosemirror.view();
+      expect(view).toEqual(node.toJSON());
+      const node2 = Node.fromJSON(schema, view);
+      expect(eq(node, node2)).toBe(true);
+    });
+
+    test('empty paragraphs', () => {
+      const node = doc(p(), p()) as Node;
+      const viewRange = FromPm.convert(node);
+      const model = Model.create(ext.prosemirror.new());
+      const prosemirror = model.s.toExt();
+      prosemirror.node.txt.editor.import(0, viewRange);
+      prosemirror.node.txt.refresh();
+      const view = prosemirror.view();
+      expect(view).toEqual(node.toJSON());
+      const node2 = Node.fromJSON(schema, view);
+      expect(eq(node, node2)).toBe(true);
+    });
+
+    test('block element <h2> with attributes', () => {
+      const node = doc(h2('hello world')) as Node;
+      const viewRange = FromPm.convert(node);
+      // console.log(JSON.stringify(node.toJSON(), null, 2));
+      // console.log(JSON.stringify(viewRange, null, 2));
+      const model = Model.create(ext.prosemirror.new());
+      const prosemirror = model.s.toExt();
+      prosemirror.node.txt.editor.import(0, viewRange);
+      prosemirror.node.txt.refresh();
+      const view = prosemirror.view();
+      // console.log(JSON.stringify(view, null, 2));
+      expect(view).toEqual(node.toJSON());
+      const node2 = Node.fromJSON(schema, view);
+      expect(eq(node, node2)).toBe(true);
+    });
+
+    test('discriminant two levels deep', () => {
+      const node = doc(
+        blockquote(blockquote(p('paragraph 1')), blockquote(p('paragraph 2'))),
+        blockquote(blockquote(p('paragraph 1')), blockquote(p('paragraph 2')), blockquote(p('paragraph 3'))),
+        blockquote(blockquote(p('paragraph 1')), blockquote(p('paragraph 2'))),
+      ) as Node;
+      const viewRange = FromPm.convert(node);
+      // console.log(JSON.stringify(node.toJSON(), null, 2));
+      // console.log(JSON.stringify(viewRange, null, 2));
+      const model = Model.create(ext.prosemirror.new());
+      const prosemirror = model.s.toExt();
+      prosemirror.node.txt.editor.import(0, viewRange);
+      prosemirror.node.txt.refresh();
+      // console.log(prosemirror.node.txt + '');
+      const view = prosemirror.view();
+      // console.log(JSON.stringify(view, null, 2));
+      expect(view).toEqual(node.toJSON());
+    });
+
+    test('can convert a two-block document', () => {
+      const node = doc(
+        h1('Hello world'),
+        blockquote(p('This is a ', strong('Prose'), strong(em('Mirror')), ' editor example.')),
+      ) as Node;
+      const viewRange = FromPm.convert(node);
+      const model = Model.create(ext.prosemirror.new());
+      const prosemirror = model.s.toExt();
+      prosemirror.node.txt.editor.import(0, viewRange);
+      prosemirror.node.txt.refresh();
+      const view = prosemirror.view();
+      expect(view).toEqual(node.toJSON());
+      const node2 = Node.fromJSON(schema, view);
+      expect(eq(node, node2)).toBe(true);
+    });
+
+    test('fuzzer 1', () => {
+      const node = fuzzer1;
+      const viewRange = FromPm.convert(node);
+      // console.log(JSON.stringify(viewRange, null, 2));
+      const model = Model.create(ext.prosemirror.new());
+      const prosemirror = model.s.toExt();
+      prosemirror.node.txt.editor.import(0, viewRange);
+      prosemirror.node.txt.refresh();
+      // console.log(prosemirror.node.txt + '');
+      const view = prosemirror.view();
+      // console.log(JSON.stringify(view, null, 2));
+      expect(view).toEqual(node.toJSON());
+      const node2 = Node.fromJSON(schema, view);
+      expect(eq(node, node2)).toBe(true);
+    });
+  });
+});
diff --git a/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/ProseMirrorApi.automated.spec.ts b/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/ProseMirrorApi.automated.spec.ts
new file mode 100644
index 0000000000..ca363c56ac
--- /dev/null
+++ b/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/ProseMirrorApi.automated.spec.ts
@@ -0,0 +1,38 @@
+import {Node} from 'prosemirror-model';
+import {ModelWithExt as Model} from '../../../json-crdt-extensions';
+import {ext} from '../../ModelWithExt';
+import * as fixtures from './fixtures';
+import {assertCanMergeInto} from './setup';
+import {schema} from 'prosemirror-test-builder';
+
+describe('.mergePmNode()', () => {
+  describe('can merge into an empty node', () => {
+    const assertCanMerge = (doc: Node) => {
+      const model = Model.create(ext.prosemirror.new());
+      const prosemirror = model.s.toExt();
+      prosemirror.mergePmNode(doc);
+      prosemirror.node.txt.refresh();
+      const view = prosemirror.view();
+      // console.log(JSON.stringify(view, null, 2));
+      // console.log(JSON.stringify(doc.toJSON(), null, 2));
+      // console.log(view);
+      expect(Node.fromJSON(schema, view).toJSON()).toEqual(doc.toJSON());
+    };
+
+    for (const [name, fixture] of Object.entries(fixtures)) {
+      test(name, () => {
+        assertCanMerge(fixture);
+      });
+    }
+  });
+
+  describe('can merge from any model to any other', () => {
+    for (const [name1, fixture1] of Object.entries(fixtures)) {
+      for (const [name2, fixture2] of Object.entries(fixtures)) {
+        test(`from ${name1} to ${name2}`, () => {
+          assertCanMergeInto(fixture1, fixture2);
+        });
+      }
+    }
+  });
+});
diff --git a/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/ProseMirrorApi.fuzzer.spec.ts b/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/ProseMirrorApi.fuzzer.spec.ts
new file mode 100644
index 0000000000..f2c8439d9e
--- /dev/null
+++ b/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/ProseMirrorApi.fuzzer.spec.ts
@@ -0,0 +1,16 @@
+import type {Node} from 'prosemirror-model';
+import {NodeToViewRangeFuzzer} from './fuzzer';
+import {assertCanMergeTrain} from './setup';
+
+test('can merge document train', () => {
+  for (let i = 0; i < 3; i++) {
+    const count = 3;
+    const docs: Node[] = [];
+    for (let i = 0; i < count; i++) {
+      const doc = NodeToViewRangeFuzzer.doc();
+      // logTree(doc.toJSON());
+      docs.push(doc);
+    }
+    assertCanMergeTrain(docs);
+  }
+});
diff --git a/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/ProseMirrorApi.spec.ts b/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/ProseMirrorApi.spec.ts
new file mode 100644
index 0000000000..000a1826c2
--- /dev/null
+++ b/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/ProseMirrorApi.spec.ts
@@ -0,0 +1,70 @@
+import * as fixtures from './fixtures';
+import {assertCanMergeTrain, assertCanMergeInto, assertEmptyMerge} from './setup';
+
+describe('.mergePmNode()', () => {
+  test('can merge "twoBlockquotes" fixture into "paragraphs" fixture', () => {
+    assertCanMergeInto(fixtures.twoBlockquotes, fixtures.paragraphs);
+    assertCanMergeInto(fixtures.paragraphs, fixtures.twoBlockquotes);
+  });
+
+  test('can merge "inlineStyles" fixture into "nestedInlines" fixture', () => {
+    assertCanMergeInto(fixtures.inlineStyles, fixtures.nestedInlines);
+    assertCanMergeInto(fixtures.nestedInlines, fixtures.inlineStyles);
+  });
+
+  test('can merge "nestedInlinesWithAttributes" fixture into "nestedInlinesWithAttributes2" fixture', () => {
+    assertCanMergeInto(fixtures.nestedInlinesWithAttributes2, fixtures.nestedInlinesWithAttributes);
+    assertCanMergeInto(fixtures.nestedInlinesWithAttributes, fixtures.nestedInlinesWithAttributes2);
+  });
+
+  test('can merge "paragraph" fixture into "nestedInlinesWithAttributes" fixture', () => {
+    assertCanMergeInto(fixtures.paragraph, fixtures.nestedInlinesWithAttributes);
+    assertCanMergeInto(fixtures.nestedInlinesWithAttributes, fixtures.paragraph);
+  });
+
+  test('can merge "inlineStyles" fixture into "blockquotes" fixture', () => {
+    assertCanMergeInto(fixtures.inlineStyles, fixtures.blockquotes);
+    assertCanMergeInto(fixtures.blockquotes, fixtures.inlineStyles);
+  });
+
+  test('can merge "headings" fixture into "realisticDoc" fixture', () => {
+    assertCanMergeInto(fixtures.headings, fixtures.realisticDoc);
+    assertCanMergeInto(fixtures.realisticDoc, fixtures.headings);
+  });
+
+  test('can merge "realisticDoc" fixture into "realisticDoc" fixture', () => {
+    assertCanMergeInto(fixtures.realisticDoc, fixtures.realisticDoc);
+  });
+
+  test('produces not changes when merging document into equivalent document', () => {
+    assertEmptyMerge(fixtures.nestedInlinesWithAttributes);
+    assertEmptyMerge(fixtures.realisticDoc);
+    assertEmptyMerge(fixtures.fuzzer1);
+  });
+
+  test('can merge all docs one into each other', () => {
+    assertCanMergeTrain([
+      fixtures.paragraphs,
+      fixtures.twoBlockquotes,
+      fixtures.inlineStyles,
+      fixtures.nestedInlines,
+      fixtures.nestedInlinesWithAttributes,
+      fixtures.nestedInlinesWithAttributes2,
+      fixtures.blockquotes,
+      fixtures.headings,
+      fixtures.realisticDoc,
+      fixtures.fuzzer1,
+
+      fixtures.nestedInlinesWithAttributes2,
+      fixtures.nestedInlines,
+      fixtures.inlineStyles,
+      fixtures.realisticDoc,
+      fixtures.nestedInlinesWithAttributes,
+      fixtures.blockquotes,
+      fixtures.fuzzer1,
+      fixtures.twoBlockquotes,
+      fixtures.headings,
+      fixtures.paragraphs,
+    ]);
+  });
+});
diff --git a/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/fixtures.ts b/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/fixtures.ts
new file mode 100644
index 0000000000..0428bee58f
--- /dev/null
+++ b/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/fixtures.ts
@@ -0,0 +1,158 @@
+import {fromJSON} from '../util';
+import {Fragment} from 'prosemirror-model';
+import {schema} from 'prosemirror-test-builder';
+import {doc, blockquote, ul, ol, li, p, h1, h2, h3, em, strong, a} from 'prosemirror-test-builder';
+
+export const fuzzer1 = fromJSON(
+  schema,
+  {
+    type: 'doc',
+    content: [
+      {
+        type: 'ordered_list',
+        attrs: {
+          order: 1,
+        },
+        content: [
+          {
+            type: 'list_item',
+            content: [
+              {
+                type: 'heading',
+                attrs: {
+                  level: 2,
+                },
+                content: [
+                  {
+                    type: 'text',
+                    text: 'abc',
+                  },
+                ],
+              },
+              {
+                type: 'ordered_list',
+                attrs: {
+                  order: 1,
+                },
+                content: [
+                  {
+                    type: 'list_item',
+                    content: [
+                      {
+                        type: 'heading',
+                        attrs: {
+                          level: 2,
+                        },
+                        content: [
+                          {
+                            type: 'text',
+                            text: 'abc',
+                          },
+                        ],
+                      },
+                    ],
+                  },
+                ],
+              },
+            ],
+          },
+        ],
+      },
+    ],
+  },
+  (nodes) => (nodes ? new (Fragment as any)(nodes) : Fragment.empty),
+);
+
+export const paragraph = doc(p('This is a paragraph.'));
+
+export const paragraphs = doc(
+  p('This is a paragraph.'),
+  p('This is another paragraph.'),
+  p('This is yet another paragraph.'),
+);
+
+export const twoBlockquotes = doc(
+  blockquote(p('This is a blockquote.')),
+  blockquote('This is another blockquote. Without a paragraph.'),
+);
+
+export const blockquotes = doc(
+  blockquote(p('This is a blockquote.')),
+  blockquote('This is another blockquote. Without a paragraph.'),
+  blockquote(p('Blockquote with two paragraphs.'), p('This is the second paragraph of the blockquote.')),
+);
+
+export const list = doc(ul(li(p('Item 1')), li(p('Item 2')), li(p('Item 3'))));
+
+export const nestedList = doc(
+  ul(
+    li(p('Item 1')),
+    li(p('Item 2'), ul(li(p('Subitem 2.1')), li(p('Subitem 2.2')), li(p('Subitem 2.3')))),
+    li(p('Item 3')),
+  ),
+);
+
+export const headings = doc(
+  h1('Heading 1'),
+  p('This is a paragraph under heading 1.'),
+  h2('Heading 2'),
+  p('This is a paragraph under heading 2.'),
+  h3('Heading 3'),
+  p('This is a paragraph under heading 3.'),
+);
+
+export const realisticDoc = doc(
+  h1('Main Title'),
+  p('This is the', em('introduction'), 'paragraph. It introduces the document and provides some context.'),
+  blockquote(p('This is a quote from someone.')),
+  h2('Section 1'),
+  p('This is the first section.'),
+  ul(
+    li(p('First item in section 1.', ' It has some details.')),
+    li(p('Second item in section 1.')),
+    li(p('Third item in section 1.')),
+  ),
+  h2('Section 2'),
+  p('This is the second section.'),
+  blockquote(p('This is another quote.')),
+  h3('Subsection 2.1'),
+  p('This is a subsection under section 2.'),
+  ol(
+    li(p('First item in subsection 2.1.')),
+    li(p('Second item in subsection 2.1.')),
+    li(p('Third item in subsection 2.1.')),
+  ),
+  h3('Subsection 2.2'),
+  p('This is another subsection under section 2.'),
+  blockquote(p('This is a quote in subsection 2.2.')),
+  h1('Conclusion'),
+  p('This is the conclusion paragraph.'),
+);
+
+export const inlineStyles = doc(
+  p(
+    'This is a paragraph with ',
+    em('emphasized text'),
+    ', ',
+    strong('strong text'),
+    ', and a link to ',
+    a({href: 'https://example.com'}, 'example.com'),
+    '.',
+  ),
+);
+
+export const nestedInlines = doc(
+  p(
+    'This is a paragraph with ',
+    em('nested ', strong('inline styles')),
+    ' and a link to ',
+    a({href: 'https://example.com'}, strong('example.com')),
+    '.',
+  ),
+);
+
+export const nestedInlinesWithAttributes = doc(p(a({href: 'https://example.com'}, strong('example.com'))));
+
+export const nestedInlinesWithAttributes2 = doc(p(strong(a({href: 'https://example.com'}, 'example.com'))));
+
+export const nestingOrderOfInlines = doc(p(em(strong('text'))), p(strong(em('text'))));
diff --git a/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/fuzzer.ts b/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/fuzzer.ts
new file mode 100644
index 0000000000..e04c6a1826
--- /dev/null
+++ b/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/fuzzer.ts
@@ -0,0 +1,94 @@
+import type {Node} from 'prosemirror-model';
+import {Fuzzer} from '@jsonjoy.com/util/lib/Fuzzer';
+import {
+  doc,
+  blockquote,
+  ul,
+  ol,
+  li,
+  p,
+  pre,
+  h1,
+  h2,
+  h3,
+  em,
+  strong,
+  type MarkBuilder,
+  a,
+} from 'prosemirror-test-builder';
+import {RandomJson} from '@jsonjoy.com/json-random';
+
+export class NodeToViewRangeFuzzer {
+  public static readonly doc = () => new NodeToViewRangeFuzzer().createDocumentNode();
+
+  private fuzzer = new Fuzzer();
+
+  private nodeCount = 0;
+  private maxNodeCount = 100;
+
+  doContinue(percent = 50): boolean {
+    if (this.nodeCount >= this.maxNodeCount) return false;
+    return this.fuzzer.randomInt(1, 100) <= percent;
+  }
+
+  createInlineNode(): ReturnType<MarkBuilder> {
+    const builder = this.fuzzer.pick([em, strong, a]);
+    this.nodeCount++;
+    if (builder === a) {
+      return a({href: RandomJson.genString(4)}, ...this.createInlineFragment());
+    } else {
+      return builder(...this.createInlineFragment());
+    }
+  }
+
+  createInlineFragment(percent = 90): (ReturnType<MarkBuilder> | string)[] {
+    const nodes: (ReturnType<MarkBuilder> | string)[] = [];
+    const count = Fuzzer.randomInt(1, 5);
+    for (let i = 0; i < count; i++) {
+      if (!this.doContinue()) {
+        this.nodeCount++;
+        nodes.push(RandomJson.genString(5));
+        break;
+      } else {
+        nodes.push(this.createInlineNode());
+      }
+    }
+    return nodes;
+  }
+
+  createBlockFragment(percent = 60): Node[] {
+    const nodes: Node[] = [];
+    while (this.doContinue(percent)) {
+      const node = this.fuzzer.pick([() => this.createLeafBlockNode(), () => this.createContainerBlockNode()]);
+      nodes.push(node());
+    }
+    return nodes;
+  }
+
+  createListFragment(percent = 50): Node[] {
+    const nodes: Node[] = [];
+    while (this.doContinue(percent)) {
+      percent = Math.max(0, percent - 10);
+      this.nodeCount++;
+      nodes.push(li(...this.createBlockFragment()));
+    }
+    return nodes;
+  }
+
+  createLeafBlockNode(): Node {
+    const builder = this.fuzzer.pick([p, pre, h1, h2, h3]);
+    this.nodeCount++;
+    return builder(...this.createInlineFragment());
+  }
+
+  createContainerBlockNode(): Node {
+    const builder = this.fuzzer.pick([blockquote, ul, ol]);
+    return builder === ul || builder === ol
+      ? builder(...this.createListFragment())
+      : builder(...this.createBlockFragment());
+  }
+
+  createDocumentNode(): Node {
+    return doc(...this.createBlockFragment(100));
+  }
+}
diff --git a/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/setup.ts b/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/setup.ts
new file mode 100644
index 0000000000..61faad5139
--- /dev/null
+++ b/packages/json-joy/src/json-crdt-extensions/prosemirror/__tests__/setup.ts
@@ -0,0 +1,63 @@
+import {ModelWithExt as Model, ext} from '../../ModelWithExt';
+import {FromPm} from '../FromPm';
+import {Node} from 'prosemirror-model';
+import {schema} from 'prosemirror-test-builder';
+
+export const assertCanConvert = (doc: Node) => {
+  const viewRange = FromPm.convert(doc);
+  const model = Model.create(ext.prosemirror.new());
+  const prosemirror = model.s.toExt();
+  prosemirror.node.txt.editor.import(0, viewRange);
+  prosemirror.node.txt.refresh();
+  const view = prosemirror.view();
+  // console.log(JSON.stringify(view, null, 2));
+  // console.log(JSON.stringify(doc.toJSON(), null, 2));
+  expect(view).toEqual(doc.toJSON());
+};
+
+export const assertCanMergeInto = (doc1: Node, doc2: Node) => {
+  const model = Model.create(ext.prosemirror.new());
+  const prosemirror = model.s.toExt();
+  prosemirror.mergePmNode(doc1);
+  prosemirror.node.txt.refresh();
+  const view = prosemirror.view();
+  // logTree(view);
+  // logTree(prosemirror.node.txt.editor.export());
+  expect(Node.fromJSON(schema, view).toJSON()).toEqual(doc1.toJSON());
+  prosemirror.mergePmNode(doc2);
+  const view2 = prosemirror.view();
+  // logTree(view2);
+  // logTree(doc2.toJSON());
+  expect(Node.fromJSON(schema, view2).toJSON()).toEqual(doc2.toJSON());
+  const model2 = Model.create(ext.prosemirror.new());
+  const prosemirror2 = model2.s.toExt();
+  const viewRange2 = FromPm.convert(doc2);
+  prosemirror2.node.txt.editor.merge(viewRange2);
+  prosemirror2.node.txt.refresh();
+  expect(prosemirror2.node.txt.editor.export()).toEqual(prosemirror.node.txt.editor.export());
+};
+
+export const assertCanMergeTrain = (docs: Node[]) => {
+  const model = Model.create(ext.prosemirror.new());
+  const prosemirror = model.s.toExt();
+  for (const doc of docs) {
+    prosemirror.mergePmNode(doc);
+    const view = prosemirror.view();
+    // logTree(view);
+    // logTree(prosemirror.node.txt.editor.export());
+    expect(Node.fromJSON(schema, view).toJSON()).toEqual(doc.toJSON());
+  }
+};
+
+export const assertEmptyMerge = (doc: Node) => {
+  const model = Model.create(ext.prosemirror.new());
+  const prosemirror = model.s.toExt();
+  const patch1 = prosemirror.mergePmNode(doc);
+  expect(patch1).not.toEqual([void 0, void 0, void 0]);
+  prosemirror.node.txt.refresh();
+  const patch2 = prosemirror.mergePmNode(doc);
+  expect(patch2).not.toEqual([void 0, void 0, void 0]);
+  prosemirror.node.txt.refresh();
+  const patch3 = prosemirror.mergePmNode(doc);
+  expect(patch3).not.toEqual([void 0, void 0, void 0]);
+};
diff --git a/packages/json-joy/src/json-crdt-extensions/prosemirror/constants.ts b/packages/json-joy/src/json-crdt-extensions/prosemirror/constants.ts
new file mode 100644
index 0000000000..31ca6a86e5
--- /dev/null
+++ b/packages/json-joy/src/json-crdt-extensions/prosemirror/constants.ts
@@ -0,0 +1,3 @@
+import {ExtensionId, ExtensionName} from '../constants';
+
+export const MNEMONIC = ExtensionName[ExtensionId.prosemirror];
diff --git a/packages/json-joy/src/json-crdt-extensions/prosemirror/index.ts b/packages/json-joy/src/json-crdt-extensions/prosemirror/index.ts
new file mode 100644
index 0000000000..5176ac7f5f
--- /dev/null
+++ b/packages/json-joy/src/json-crdt-extensions/prosemirror/index.ts
@@ -0,0 +1,17 @@
+import {ExtensionId} from '../constants';
+import {ProseMirrorNode} from './ProseMirrorNode';
+import {ProseMirrorApi} from './ProseMirrorApi';
+import {MNEMONIC} from './constants';
+import {Extension} from '../../json-crdt/extensions/Extension';
+import {SCHEMA} from '../peritext/constants';
+import type {PmDataNode} from './types';
+
+export {ProseMirrorNode, ProseMirrorApi};
+
+export const prosemirror = new Extension<
+  ExtensionId.prosemirror,
+  PmDataNode,
+  ProseMirrorNode,
+  ProseMirrorApi,
+  [text?: string]
+>(ExtensionId.prosemirror, MNEMONIC, ProseMirrorNode, ProseMirrorApi, (text: string = '') => SCHEMA(text));
diff --git a/packages/json-joy/src/json-crdt-extensions/prosemirror/types.ts b/packages/json-joy/src/json-crdt-extensions/prosemirror/types.ts
new file mode 100644
index 0000000000..98f5f41755
--- /dev/null
+++ b/packages/json-joy/src/json-crdt-extensions/prosemirror/types.ts
@@ -0,0 +1,44 @@
+import type {PeritextDataNode} from '../peritext/types';
+
+export type PmDataNode = PeritextDataNode;
+
+export interface PmJsonNode {
+  type: string;
+  attrs?: Record<string, unknown>;
+  content?: (PmJsonNode | PmJsonTextNode)[];
+  marks?: PmJsonMark[];
+}
+
+export interface PmJsonTextNode extends PmJsonNode {
+  text: string;
+}
+export interface PmJsonMark {
+  type: string;
+  attrs?: PmAttrs;
+}
+
+export type PmAttrs = Record<string, unknown>;
+
+export interface PmNode {
+  readonly type: PmNodeType;
+  readonly attrs?: PmAttrs;
+  readonly content?: PmFragment;
+  readonly marks?: readonly PmMark[];
+}
+
+export interface PmTextNode extends PmNode {
+  readonly text: string;
+}
+
+export interface PmNodeType {
+  readonly name: string;
+}
+
+export interface PmFragment {
+  readonly content: readonly (PmNode | PmTextNode)[];
+}
+
+export interface PmMark {
+  readonly type: PmNodeType;
+  readonly attrs?: PmAttrs;
+}
diff --git a/packages/json-joy/src/json-crdt-extensions/prosemirror/util.ts b/packages/json-joy/src/json-crdt-extensions/prosemirror/util.ts
new file mode 100644
index 0000000000..4e90a0b76c
--- /dev/null
+++ b/packages/json-joy/src/json-crdt-extensions/prosemirror/util.ts
@@ -0,0 +1,24 @@
+import type {Fragment, Mark, Node, Schema} from 'prosemirror-model';
+import type {PmJsonTextNode, PmJsonNode} from './types';
+
+export const fromJSON = (
+  schema: Schema,
+  json: PmJsonNode | PmJsonTextNode,
+  createFragment: (nodes?: Node[]) => Fragment,
+): Node => {
+  const {type, attrs, content, marks, text} = json as PmJsonNode & PmJsonTextNode;
+  const _marks: Mark[] | undefined = Array.isArray(marks)
+    ? marks.map((mark) => schema.mark(mark.type, mark.attrs))
+    : void 0;
+  return type === 'text'
+    ? schema.text(typeof text === 'string' ? text : '', _marks)
+    : (schema as any)
+        .nodeType(type)
+        .create(
+          attrs,
+          Array.isArray(content)
+            ? createFragment(content.map((val) => fromJSON(schema, val, createFragment)))
+            : createFragment(),
+          _marks,
+        );
+};
diff --git a/packages/json-joy/src/json-crdt/model/api/types.ts b/packages/json-joy/src/json-crdt/model/api/types.ts
index 1789076495..726a91f9a5 100644
--- a/packages/json-joy/src/json-crdt/model/api/types.ts
+++ b/packages/json-joy/src/json-crdt/model/api/types.ts
@@ -1,4 +1,11 @@
-import type {PeritextNode, PeritextApi, QuillDeltaNode, QuillDeltaApi} from '../../../json-crdt-extensions';
+import type {
+  PeritextNode,
+  PeritextApi,
+  QuillDeltaNode,
+  QuillDeltaApi,
+  ProseMirrorNode,
+  ProseMirrorApi,
+} from '../../../json-crdt-extensions';
 import type * as types from '../../nodes';
 import type * as nodes from './nodes';
 import type {Path} from '@jsonjoy.com/json-pointer';
@@ -26,7 +33,9 @@ export type JsonNodeApi<N> = N extends types.ConNode<any>
                   ? PeritextApi
                   : N extends QuillDeltaNode
                     ? QuillDeltaApi
-                    : never;
+                    : N extends ProseMirrorNode
+                      ? ProseMirrorApi
+                      : never;
 
 export type ApiOperation = ApiOperationAdd | ApiOperationReplace | ApiOperationMerge | ApiOperationRemove;
 
diff --git a/packages/json-joy/src/json-crdt/schema/types.ts b/packages/json-joy/src/json-crdt/schema/types.ts
index 79019a13ab..cb96f4bd1b 100644
--- a/packages/json-joy/src/json-crdt/schema/types.ts
+++ b/packages/json-joy/src/json-crdt/schema/types.ts
@@ -1,6 +1,6 @@
 import type {ExtensionId} from '../../json-crdt-extensions';
 import type {MvalNode} from '../../json-crdt-extensions/mval/MvalNode';
-import type {PeritextNode, QuillDeltaNode} from '../../json-crdt-extensions';
+import type {PeritextNode, QuillDeltaNode, ProseMirrorNode} from '../../json-crdt-extensions';
 import type {nodes as builder} from '../../json-crdt-patch';
 import type {ExtNode} from '../extensions/ExtNode';
 import type * as nodes from '../nodes';
@@ -24,15 +24,18 @@ export type SchemaToJsonNode<S> = S extends builder.str<infer T>
                 ? ExtensionNode<PeritextNode>
                 : S extends builder.ext<ExtensionId.quill, any>
                   ? ExtensionNode<QuillDeltaNode>
-                  : S extends builder.ext<ExtensionId.mval, any>
-                    ? ExtensionNode<MvalNode>
-                    : nodes.JsonNode;
+                  : S extends builder.ext<ExtensionId.prosemirror, any>
+                    ? ExtensionNode<ProseMirrorNode>
+                    : S extends builder.ext<ExtensionId.mval, any>
+                      ? ExtensionNode<MvalNode>
+                      : nodes.JsonNode;
 
 export type ExtensionNode<E extends ExtNode<any>> = nodes.VecNode<ExtensionVecData<E>>;
 
-export type ExtensionVecData<EDataNode extends ExtNode<any, any>> = {
-  __BRAND__: 'ExtVecData';
-} & [header: nodes.ConNode<Uint8Array>, data: EDataNode];
+export type ExtensionVecData<EDataNode extends ExtNode<any, any>> = {__BRAND__: 'ExtVecData'} & [
+  header: nodes.ConNode<Uint8Array>,
+  data: EDataNode,
+];
 
 // prettier-ignore
 export type VecNodeExtensionData<N> = N extends nodes.VecNode<infer T>
@@ -56,9 +59,11 @@ export type JsonNodeToSchema<N> = N extends nodes.StrNode<infer T>
               ? builder.ext<ExtensionId.peritext, any>
               : EDataNode extends QuillDeltaNode
                 ? builder.ext<ExtensionId.quill, any>
-                : EDataNode extends MvalNode
-                  ? builder.ext<ExtensionId.mval, any>
-                  : builder.ext<number, any>
+                : EDataNode extends ProseMirrorNode
+                  ? builder.ext<ExtensionId.prosemirror, any>
+                  : EDataNode extends MvalNode
+                    ? builder.ext<ExtensionId.mval, any>
+                    : builder.ext<number, any>
             : builder.vec<{[K in keyof T]: JsonNodeToSchema<T[K]>}>
           : N extends nodes.ObjNode<infer T>
             ? builder.obj<{[K in keyof T]: JsonNodeToSchema<T[K]>}>
diff --git a/yarn.lock b/yarn.lock
index f397c0f8df..bd7c8af546 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -7072,11 +7072,10 @@ __metadata:
     "@jsonjoy.com/json-expression": "workspace:*"
     "@jsonjoy.com/json-pack": "workspace:*"
     "@jsonjoy.com/json-pointer": "workspace:*"
+    "@jsonjoy.com/json-random": "workspace:*"
     "@jsonjoy.com/json-type": "workspace:*"
     "@jsonjoy.com/util": "workspace:*"
-    "@monaco-editor/react": "npm:^4.7.0"
     "@radix-ui/react-icons": "npm:^1.3.1"
-    "@types/node": "npm:^24.8.1"
     "@types/react": "npm:^18.3.11"
     "@types/react-dom": "npm:^18.3.0"
     arg: "npm:^5.0.2"
@@ -7092,7 +7091,6 @@ __metadata:
     jest: "npm:^29.7.0"
     json-crdt-traces: "https://github.com/streamich/json-crdt-traces#ec825401dc05cbb74b9e0b3c4d6527399f54d54d"
     json-logic-js: "npm:^2.0.2"
-    monaco-editor: "npm:^0.54.0"
     nano-css: "npm:^5.6.2"
     nano-theme: "npm:^1.4.3"
     nice-ui: "npm:^1.30.0"