diff --git a/frontend/src/plugins/builtin/core-annotate/index.ts b/frontend/src/plugins/builtin/core-annotate/index.ts
index dcd84ad..b303456 100644
--- a/frontend/src/plugins/builtin/core-annotate/index.ts
+++ b/frontend/src/plugins/builtin/core-annotate/index.ts
@@ -127,15 +127,81 @@ export const dimensionTool: ToolExtensionV2 = make2PointAnnotate('dimension', 'B
 export const leaderTool: ToolExtensionV2 = make2PointAnnotate('leader', 'Leader', '\u21b1', buildLeader);
 
 /** V2-Plugin: Beschriftung/Bemaßung (A4.4). */
+// ─────────────────────────────────────────────────────────────
+// Task D4: MTEXT — Mehrzeiliger Text mit optionalem Rahmen.
+// Klick platziert Text (Inhalt aus Options, Zeilenumbrüche erhalten),
+// frame-Option erzeugt ein rect in derselben Transaktion (1 Undo).
+// ─────────────────────────────────────────────────────────────
+
+export const mtextTool: ToolExtensionV2 = {
+  manifest: {
+    id: 'mtext',
+    label: 'Mehrzeilentext',
+    icon: '¶',
+    ribbonTab: 'format',
+    tags: ['basic'],
+    description: 'Mehrzeiligen Text platzieren (Rahmen optional, Task D4)',
+  },
+  optionsSchema: [
+    { key: 'text', label: 'Text', type: 'text' },
+    { key: 'fontSize', label: 'Größe', type: 'number', min: 6, max: 72 },
+    { key: 'frame', label: 'Rahmen', type: 'checkbox' },
+  ],
+  handlers: {
+    down(e, ctx) {
+      const c = ctx as FullToolContext;
+      if (!c.doc) return;
+      const layerId = (c.options.layerId as string | undefined) ?? 'layer-0';
+      const text = (c.options.text as string | undefined) ?? '';
+      const fontSize = (c.options.fontSize as number | undefined) ?? 12;
+      const frame = (c.options.frame as boolean | undefined) ?? false;
+      // Newline ohne Escape-Probleme: charCode 10
+      const NL = String.fromCharCode(10);
+      const lines = text.split(NL);
+      const lineCount = Math.max(1, lines.length);
+      const maxLen = lines.reduce((m, l) => Math.max(m, l.length), 0);
+      const textW = maxLen * fontSize * 0.6;
+      const textH = lineCount * fontSize * 1.4;
+      const els: CADElement[] = [{
+        id: uid('mtext'),
+        type: 'text',
+        layerId,
+        x: e.world.x,
+        y: e.world.y,
+        width: textW,
+        height: textH,
+        properties: { text, fontSize, mtext: true },
+      } as unknown as CADElement];
+      if (frame) {
+        const pad = fontSize * 0.4;
+        els.push({
+          id: uid('mtextframe'),
+          type: 'rect',
+          layerId,
+          x: e.world.x,
+          y: e.world.y,
+          width: textW + pad * 2,
+          height: textH + pad * 2,
+          properties: { stroke: '#9aa0a6', strokeWidth: 1, fill: 'none' },
+        } as unknown as CADElement);
+      }
+      c.doc.transact(() => {
+        for (const el of els) c.doc!.addElement(el);
+      });
+      ctx.setStatus(`Mehrzeilentext platziert (${lineCount} Zeile(n)${frame ? ', mit Rahmen' : ''})`);
+    },
+  },
+};
+
 export const coreAnnotatePlugin: PluginV2 = {
   manifest: {
     id: 'core-annotate',
     name: 'Beschriftung (Kern)',
-    version: '1.0.0',
+    version: '1.1.0',
     author: 'web-cad team',
     description: 'Text, Bemaßung, Leader (V2).',
     category: 'tools',
     enabledByDefault: true,
   },
-  tools: [textTool, dimensionTool, leaderTool],
+  tools: [textTool, dimensionTool, leaderTool, mtextTool],
 };
diff --git a/frontend/tests/mtextTool.test.ts b/frontend/tests/mtextTool.test.ts
new file mode 100644
index 0000000..eaf37e5
--- /dev/null
+++ b/frontend/tests/mtextTool.test.ts
@@ -0,0 +1,101 @@
+/**
+ * Task D4 – MTEXT-Tool: Mehrzeiliger Text mit/ohne Rahmen.
+ *
+ * Klick platziert mehrzeiligen Text (Inhalt aus Options, Zeilen-
+ * umbrueche), fontSize-Option, optionale Rahmen-Option erzeugt ein
+ * rect-Element in derselben Transaktion (1 Undo-Schritt).
+ */
+import { describe, it, expect } from 'vitest';
+import { mtextTool } from '../src/plugins/builtin/core-annotate';
+import { CADDocument } from '../src/kernel/document/CADDocument';
+import { createInMemoryDoc } from './helpers/inMemoryDoc';
+import type { CADElement, Pt } from '../src/types/cad.types';
+
+function mkCtx(options: Record<string, unknown> = {}) {
+  const { ydoc } = createInMemoryDoc();
+  const doc = new CADDocument(ydoc);
+  const statuses: string[] = [];
+  const ctx: any = {
+    doc,
+    options,
+    setStatus: (m: string) => statuses.push(m),
+    setPreview: (_el: CADElement | null) => {},
+  };
+  return { ctx, doc, statuses };
+}
+
+function pe(x: number, y: number): { world: Pt } {
+  return { world: { x, y } } as never;
+}
+
+describe('D4: mtextTool', () => {
+  it('platziert mehrzeiligen Text mit Zeilenumbruechen aus den Options', () => {
+    const { ctx, doc } = mkCtx({ text: 'Zeile 1\nZeile 2\nZeile 3', fontSize: 14 });
+    mtextTool.handlers.down!(pe(100, 50), ctx);
+    const els = doc.getAllElements();
+    expect(els).toHaveLength(1);
+    const el = els[0];
+    expect(el.type).toBe('text');
+    expect(el.x).toBe(100);
+    expect(el.y).toBe(50);
+    expect(el.properties.text).toBe('Zeile 1\nZeile 2\nZeile 3');
+    expect(el.properties.fontSize).toBe(14);
+    expect(el.properties.mtext).toBe(true);
+  });
+
+  it('Rahmen-Option erzeugt zusaetzliches rect in derselben Transaktion (1 Undo)', () => {
+    const { ctx, doc } = mkCtx({ text: 'Mit Rahmen', frame: true });
+    mtextTool.handlers.down!(pe(0, 0), ctx);
+    const els = doc.getAllElements();
+    expect(els).toHaveLength(2);
+    const texts = els.filter((e) => e.type === 'text');
+    const rects = els.filter((e) => e.type === 'rect');
+    expect(texts).toHaveLength(1);
+    expect(rects).toHaveLength(1);
+    expect(rects[0].x).toBeCloseTo(0, 5);
+    expect(rects[0].y).toBeCloseTo(0, 5);
+    doc.undo();
+    expect(doc.getAllElements()).toHaveLength(0);
+  });
+
+  it('ohne frame-Option: nur Text, kein rect', () => {
+    const { ctx, doc } = mkCtx({ text: 'Ohne Rahmen' });
+    mtextTool.handlers.down!(pe(0, 0), ctx);
+    expect(doc.getAllElements().filter((e) => e.type === 'rect')).toHaveLength(0);
+  });
+
+  it('Standard-Text wenn Options leer: MTEXT-Platzhalter leer (Editor bearbeitet spaeter)', () => {
+    const { ctx, doc } = mkCtx({});
+    mtextTool.handlers.down!(pe(10, 10), ctx);
+    const el = doc.getAllElements()[0];
+    expect(el.properties.text).toBe('');
+    expect(el.properties.fontSize).toBe(12); // Default
+  });
+
+  it('OptionsSchema: text/number/checkbox-Felder', () => {
+    const schema = mtextTool.optionsSchema ?? [];
+    const keys = schema.map((f) => f.key);
+    expect(keys).toContain('text');
+    expect(keys).toContain('fontSize');
+    expect(keys).toContain('frame');
+    const textField = schema.find((f) => f.key === 'text');
+    expect(textField!.type).toBe('text');
+    const frameField = schema.find((f) => f.key === 'frame');
+    expect(frameField!.type).toBe('checkbox');
+  });
+
+  it('Rahmenhoehe waechst mit Zeilenzahl', () => {
+    const { ctx: ctx1, doc: doc1 } = mkCtx({ text: 'eine Zeile', frame: true });
+    mtextTool.handlers.down!(pe(0, 0), ctx1);
+    const { ctx: ctx3, doc: doc3 } = mkCtx({ text: 'eins\nzwei\ndrei', frame: true });
+    mtextTool.handlers.down!(pe(0, 0), ctx3);
+    const rect1 = doc1.getAllElements().find((e) => e.type === 'rect')!;
+    const rect3 = doc3.getAllElements().find((e) => e.type === 'rect')!;
+    expect(rect3.height).toBeGreaterThan(rect1.height);
+  });
+
+  it('Manifest: id=mtext, tags basic', () => {
+    expect(mtextTool.manifest.id).toBe('mtext');
+    expect((mtextTool.manifest.tags ?? [])).toContain('basic');
+  });
+});