diff --git a/frontend/src/plugins/builtin/event-tools/index.ts b/frontend/src/plugins/builtin/event-tools/index.ts
index 8dcfb1e..f2d9466 100644
--- a/frontend/src/plugins/builtin/event-tools/index.ts
+++ b/frontend/src/plugins/builtin/event-tools/index.ts
@@ -466,29 +466,34 @@ export function snapTrussToDock(
 ): TrussDock | null {
   let best: { dock: TrussDock; dist: number } | null = null;
   for (const el of existing) {
-    if (String(el.type) !== 'truss' || el.properties.truss !== true) continue;
+    const isTruss = String(el.type) === 'truss' && el.properties.truss === true;
+    const isCorner = String(el.type) === 'boxcorner' && el.properties.boxcorner === true;
+    if (!isTruss && !isCorner) continue;
     const rotDeg = (el.properties.rotation as number | undefined) ?? 0;
-    const rot = (rotDeg * Math.PI) / 180;
-    const dx = Math.cos(rot);
-    const dy = Math.sin(rot);
-    const half = newLength / 2;
-    const ends = trussEndpoints(el);
+    const ends = isTruss ? trussEndpoints(el) : boxcornerEndpoints(el);
     for (let endIdx = 0; endIdx < ends.length; endIdx++) {
       const end = ends[endIdx];
       const dist = Math.hypot(cursor.x - end.x, cursor.y - end.y);
       if (dist > tolerance) continue;
       if (best && dist >= best.dist) continue;
-      // Neue Traverse: fuehrt VOM Dock-Ende WEG von der Anker-Traverse.
-      // Endpunkt 0 (Start) -> Gegenrichtung (rot+180), Endpunkt 1 -> vorwaerts.
-      const dir = endIdx === 0 ? -1 : 1;
-      const centerX = end.x + dx * half * dir;
-      const centerY = end.y + dy * half * dir;
-      const newRot = endIdx === 0 ? (rotDeg + 180) % 360 : rotDeg;
+      // Weg-Richtung VOM Dock-Ende (arm-spezifisch):
+      // Truss-Start (idx 0) = Gegenrichtung (rot+180), Truss-Ende (idx 1) = rot,
+      // Boxcorner-Arm1 (idx 0) = rot, Boxcorner-Arm2 (idx 1) = rot+90.
+      let dirDeg: number;
+      if (isTruss) {
+        dirDeg = endIdx === 0 ? (rotDeg + 180) % 360 : rotDeg;
+      } else {
+        dirDeg = endIdx === 0 ? rotDeg : (rotDeg + 90) % 360;
+      }
+      const dirRad = (dirDeg * Math.PI) / 180;
+      const half = newLength / 2;
+      const centerX = end.x + Math.cos(dirRad) * half;
+      const centerY = end.y + Math.sin(dirRad) * half;
       best = {
         dist,
         dock: {
           center: { x: centerX, y: centerY },
-          rotationDeg: newRot,
+          rotationDeg: dirDeg,
           dockedTo: el.id,
         },
       };
@@ -505,19 +510,23 @@ function makeTrussElement(
   length: number,
   rotationDeg: number,
   layerId: string,
+  trussWidth = 29,
 ): CADElement {
   const rad = (rotationDeg * Math.PI) / 180;
-  const w = Math.abs(length * Math.cos(rad)) || length;
-  const h = Math.abs(length * Math.sin(rad)) || 20;
+  const w = Math.abs(length * Math.cos(rad)) + Math.abs(trussWidth * Math.sin(rad));
+  const h = Math.abs(length * Math.sin(rad)) + Math.abs(trussWidth * Math.cos(rad));
   return {
     id: `truss_${Date.now().toString(36)}_${Math.random().toString(36).slice(2, 9)}`,
     type: 'truss',
     layerId,
     x: center.x,
     y: center.y,
-    width: Math.max(w, 20),
-    height: 20,
-    properties: { length, rotation: rotationDeg, truss: true, stroke: '#9aa0a6', strokeWidth: 2, fill: '#6b7280' },
+    width: Math.max(w, trussWidth),
+    height: Math.max(h, trussWidth),
+    properties: {
+      length, rotation: rotationDeg, trussWidth, truss: true,
+      stroke: '#9aa0a6', strokeWidth: 2, fill: '#6b7280',
+    },
   } as unknown as CADElement;
 }
 
@@ -534,10 +543,12 @@ export const trussTool: ToolExtensionV2 = {
   },
   optionsSchema: [
     { key: 'length', label: 'Länge (cm)', type: 'select', options: [
+      { value: '50', label: '50 cm' },
       { value: '100', label: '100 cm' },
       { value: '200', label: '200 cm' },
-      { value: '290', label: '290 cm' },
+      { value: '300', label: '300 cm' },
     ] },
+    { key: 'trussWidth', label: 'Breite (cm)', type: 'number', min: 10, max: 60 },
   ],
   handlers: {
     down(e, ctx) {
@@ -548,13 +559,14 @@ export const trussTool: ToolExtensionV2 = {
       const c = ctx as FullToolContext;
       if (!trussDragStart) return;
       const length = Number((c.options.length as string | undefined) ?? 200) || 200;
-      // Magnet-Vorschau: dockt der Cursor an ein Traversen-Ende?
+      const trussWidth = (c.options.trussWidth as number | undefined) ?? 29;
+      // Magnet-Vorschau: dockt der Cursor an ein Traversen-/Ecken-Ende?
       const existing = c.doc ? (c.doc.getAllElements() as CADElement[]).filter(
-        (el) => String(el.type) === 'truss',
+        (el) => String(el.type) === 'truss' || String(el.type) === 'boxcorner',
       ) : [];
       const dock = snapTrussToDock(existing, trussDragStart, length, DOCK_TOLERANCE);
       if (dock) {
-        ctx.setPreview?.(makeTrussElement(dock.center, length, dock.rotationDeg, 'layer-0'));
+        ctx.setPreview?.(makeTrussElement(dock.center, length, dock.rotationDeg, 'layer-0', trussWidth));
         return;
       }
       // Frei: Richtung aus Drag
@@ -570,22 +582,23 @@ export const trussTool: ToolExtensionV2 = {
       ctx.setPreview?.(null);
       if (!start || !c.doc) return;
       const length = Number((c.options.length as string | undefined) ?? 200) || 200;
+      const trussWidth = (c.options.trussWidth as number | undefined) ?? 29;
       const layerId = (c.options.layerId as string | undefined) ?? 'layer-0';
-      // MAGNETISCH: Dock-Pruefung am Drag-Startpunkt
+      // MAGNETISCH: Dock-Pruefung am Drag-Startpunkt (Traversen UND Ecken)
       const existing = (c.doc.getAllElements() as CADElement[]).filter(
-        (el) => String(el.type) === 'truss',
+        (el) => String(el.type) === 'truss' || String(el.type) === 'boxcorner',
       );
       const dock = snapTrussToDock(existing, start, length, DOCK_TOLERANCE);
       let el: CADElement;
       if (dock) {
-        el = makeTrussElement(dock.center, length, dock.rotationDeg, layerId);
-        ctx.setStatus(`Traverse angedockt an ${dock.dockedTo} (${length}cm)`);
+        el = makeTrussElement(dock.center, length, dock.rotationDeg, layerId, trussWidth);
+        ctx.setStatus(`Traverse angedockt an ${dock.dockedTo} (${length}cm, Breite ${trussWidth}cm)`);
       } else {
         const ang = (Math.atan2(e.world.y - start.y, e.world.x - start.x) * 180) / Math.PI;
         const cx = (start.x + e.world.x) / 2;
         const cy = (start.y + e.world.y) / 2;
-        el = makeTrussElement({ x: cx, y: cy }, length, ang, layerId);
-        ctx.setStatus(`Traverse platziert (${length}cm)`);
+        el = makeTrussElement({ x: cx, y: cy }, length, ang, layerId, trussWidth);
+        ctx.setStatus(`Traverse platziert (${length}cm, Breite ${trussWidth}cm)`);
       }
       c.doc.transact(() => { c.doc!.addElement(el); });
     },
@@ -597,6 +610,156 @@ export const trussTool: ToolExtensionV2 = {
   },
 };
 
+// ─────────────────────────────────────────────────────────────
+// Task CAD-8: Boxcorner (Eck-Traverse) — L-foermiges Element
+// mit zwei Armen (rot und rot+90). Magnetisch: dockt an
+// Traversen-Enden und andere Ecken; Traversen docken an die
+// Armenden. DREHBAR via properties.rotation (PropertiesPanel).
+// ─────────────────────────────────────────────────────────────
+
+/** Armenden einer Boxcorner: Endpunkte beider Arme vom Eckpunkt. */
+export function boxcornerEndpoints(el: CADElement): [Pt, Pt] {
+  const armLength = (el.properties.armLength as number | undefined) ?? 50;
+  const rotDeg = (el.properties.rotation as number | undefined) ?? 0;
+  const rot = (rotDeg * Math.PI) / 180;
+  const rot2 = ((rotDeg + 90) * Math.PI) / 180;
+  return [
+    { x: el.x + Math.cos(rot) * armLength, y: el.y + Math.sin(rot) * armLength },
+    { x: el.x + Math.cos(rot2) * armLength, y: el.y + Math.sin(rot2) * armLength },
+  ];
+}
+
+export interface CornerDock {
+  vertex: Pt;
+  rotationDeg: number;
+  dockedTo: string;
+}
+
+/**
+ * Magnetisches Andocken einer Ecke (rein): dockt an Traversen-
+ * Enden und Ecken-Armenden; am Traversen-Start-Ende wird die
+ * Gegenrichtung uebernommen (rot+180), damit Reihen nach aussen
+ * wachsen.
+ */
+export function cornerDockToDock(
+  existing: CADElement[],
+  cursor: Pt,
+  tolerance: number,
+): CornerDock | null {
+  let best: { dock: CornerDock; dist: number } | null = null;
+  for (const el of existing) {
+    const isTruss = String(el.type) === 'truss' && el.properties.truss === true;
+    const isCorner = String(el.type) === 'boxcorner' && el.properties.boxcorner === true;
+    if (!isTruss && !isCorner) continue;
+    const rotDeg = (el.properties.rotation as number | undefined) ?? 0;
+    const ends = isTruss ? trussEndpoints(el) : boxcornerEndpoints(el);
+    for (let endIdx = 0; endIdx < ends.length; endIdx++) {
+      const end = ends[endIdx];
+      const dist = Math.hypot(cursor.x - end.x, cursor.y - end.y);
+      if (dist > tolerance) continue;
+      if (best && dist >= best.dist) continue;
+      const dir = isTruss && endIdx === 0 ? -1 : 1;
+      const newRot = isTruss && endIdx === 0 ? (rotDeg + 180) % 360 : rotDeg;
+      void dir;
+      best = {
+        dist,
+        dock: { vertex: { x: end.x, y: end.y }, rotationDeg: newRot, dockedTo: el.id },
+      };
+    }
+  }
+  return best ? best.dock : null;
+}
+
+function makeBoxcornerElement(
+  vertex: Pt,
+  armLength: number,
+  rotationDeg: number,
+  trussWidth: number,
+  layerId: string,
+): CADElement {
+  return {
+    id: `boxcorner_${Date.now().toString(36)}_${Math.random().toString(36).slice(2, 9)}`,
+    type: 'boxcorner',
+    layerId,
+    x: vertex.x,
+    y: vertex.y,
+    width: armLength + trussWidth,
+    height: armLength + trussWidth,
+    properties: {
+      armLength, trussWidth, rotation: rotationDeg, boxcorner: true,
+      stroke: '#9aa0a6', strokeWidth: 2, fill: '#6b7280',
+    },
+  } as unknown as CADElement;
+}
+
+let cornerDragStart: Pt | null = null;
+
+export const boxCornerTool: ToolExtensionV2 = {
+  manifest: {
+    id: 'boxcorner',
+    label: 'Eck-Traverse (magnetisch)',
+    icon: '╭',
+    ribbonTab: 'insert',
+    tags: ['basic'],
+    description: 'Eck-Traverse (Boxcorner): Drag = Richtung, dockt magnetisch an (CAD-8)',
+  },
+  optionsSchema: [
+    { key: 'armLength', label: 'Armlänge (cm)', type: 'number', min: 20, max: 150 },
+    { key: 'trussWidth', label: 'Breite (cm)', type: 'number', min: 10, max: 60 },
+  ],
+  handlers: {
+    down(e, ctx) {
+      cornerDragStart = e.world;
+      ctx.setStatus('Eck-Traverse: Richtung ziehen (dockt automatisch an)');
+    },
+    move(e, ctx) {
+      const c = ctx as FullToolContext;
+      if (!cornerDragStart) return;
+      const armLength = (c.options.armLength as number | undefined) ?? 50;
+      const trussWidth = (c.options.trussWidth as number | undefined) ?? 29;
+      const existing = c.doc ? (c.doc.getAllElements() as CADElement[]).filter(
+        (el) => String(el.type) === 'truss' || String(el.type) === 'boxcorner',
+      ) : [];
+      const dock = cornerDockToDock(existing, cornerDragStart, DOCK_TOLERANCE);
+      if (dock) {
+        ctx.setPreview?.(makeBoxcornerElement(dock.vertex, armLength, dock.rotationDeg, trussWidth, 'layer-0'));
+        return;
+      }
+      const ang = (Math.atan2(e.world.y - cornerDragStart.y, e.world.x - cornerDragStart.x) * 180) / Math.PI;
+      ctx.setPreview?.(makeBoxcornerElement(cornerDragStart, armLength, ang, trussWidth, 'layer-0'));
+    },
+    up(e, ctx) {
+      const c = ctx as FullToolContext;
+      const start = cornerDragStart;
+      cornerDragStart = null;
+      ctx.setPreview?.(null);
+      if (!start || !c.doc) return;
+      const armLength = (c.options.armLength as number | undefined) ?? 50;
+      const trussWidth = (c.options.trussWidth as number | undefined) ?? 29;
+      const layerId = (c.options.layerId as string | undefined) ?? 'layer-0';
+      const existing = (c.doc.getAllElements() as CADElement[]).filter(
+        (el) => String(el.type) === 'truss' || String(el.type) === 'boxcorner',
+      );
+      const dock = cornerDockToDock(existing, start, DOCK_TOLERANCE);
+      let el: CADElement;
+      if (dock) {
+        el = makeBoxcornerElement(dock.vertex, armLength, dock.rotationDeg, trussWidth, layerId);
+        ctx.setStatus(`Eck-Traverse angedockt an ${dock.dockedTo}`);
+      } else {
+        const ang = (Math.atan2(e.world.y - start.y, e.world.x - start.x) * 180) / Math.PI;
+        el = makeBoxcornerElement(start, armLength, ang, trussWidth, layerId);
+        ctx.setStatus(`Eck-Traverse platziert (${armLength}cm Arme, Breite ${trussWidth}cm)`);
+      }
+      c.doc.transact(() => { c.doc!.addElement(el); });
+    },
+    cancel(ctx) {
+      cornerDragStart = null;
+      ctx.setPreview?.(null);
+      ctx.setStatus('Eck-Traverse abgebrochen');
+    },
+  },
+};
+
 export const eventToolsV2Plugin: PluginV2 = {
   manifest: {
     id: 'event-tools',
@@ -607,5 +770,5 @@ export const eventToolsV2Plugin: PluginV2 = {
     category: 'elements',
     enabledByDefault: true,
   },
-  tools: [chairTool, seatingRowToolDrag, seatingBlockToolDrag, tableTool, stageTool, arcRowTool, kinoTemplateTool, banquetTemplateTool, standingTableTemplateTool, podiumTemplateTool, curtainTool, spotlightTool, barrierTool, trussTool],
+  tools: [chairTool, seatingRowToolDrag, seatingBlockToolDrag, tableTool, stageTool, arcRowTool, kinoTemplateTool, banquetTemplateTool, standingTableTemplateTool, podiumTemplateTool, curtainTool, spotlightTool, barrierTool, trussTool, boxCornerTool],
 };
diff --git a/frontend/src/render/pixi/elementDrawers.ts b/frontend/src/render/pixi/elementDrawers.ts
index acceb18..90e6aba 100644
--- a/frontend/src/render/pixi/elementDrawers.ts
+++ b/frontend/src/render/pixi/elementDrawers.ts
@@ -400,39 +400,78 @@ export function elementToPrimitives(el: CADElement, attrDefs?: Array<{ tag: stri
     }
 
     case 'truss': {
-      // Traverse (CAD-7): Balken als Rechteck + 2 Gurtlinien entlang
-      // der Rotation (wie ein Fachwerk-Profil)
+      // Traverse (CAD-7/8): ROTIERTES Rechteck-Polygon + Gurtlinien
+      // entlang der Richtung (Fachwerk-Profil), Breite = trussWidth.
       const length = (props.length as number | undefined) ?? el.width;
+      const tWidth = (props.trussWidth as number | undefined) ?? el.height ?? 29;
       const rotDeg = (props.rotation as number | undefined) ?? 0;
       const rad = (rotDeg * Math.PI) / 180;
-      const dx = Math.cos(rad) * (length / 2);
-      const dy = Math.sin(rad) * (length / 2);
-      const nx = -Math.sin(rad) * 10; // Normalen-Offset (halbe Hoehe)
-      const ny = Math.cos(rad) * 10;
+      const ux = Math.cos(rad), uy = Math.sin(rad);          // Laengsrichtung
+      const nx = -Math.sin(rad), ny = Math.cos(rad);         // Normalenrichtung
+      const hl = length / 2, hw = tWidth / 2;
       const c = { x: el.x, y: el.y };
-      return [
+      const corner = (su: number, sv: number): { x: number; y: number } => ({
+        x: c.x + ux * (hl * su) + nx * (hw * sv),
+        y: c.y + uy * (hl * su) + ny * (hw * sv),
+      });
+      const pts = [corner(-1, -1), corner(1, -1), corner(1, 1), corner(-1, 1)];
+      const strokeCol = (props.stroke as string | undefined) ?? '#9aa0a6';
+      const out: ShapePrimitive[] = [
         {
-          kind: 'rect',
-          x: c.x - dx, y: c.y - dy,
-          w: length, h: 20,
-          fill: fillOrNull(props.fill) ?? '#6b7280',
-          stroke: (props.stroke as string | undefined) ?? '#9aa0a6',
+          kind: 'polyline',
+          points: pts,
+          close: true,
+          stroke: strokeCol,
           strokeWidth: 2,
         },
-        // Gurtlinien oben/unten entlang der Traverse
+        // Gurtlinien oben/unten
         {
           kind: 'line',
-          from: { x: c.x - dx + nx, y: c.y - dy + ny },
-          to: { x: c.x + dx + nx, y: c.y + dy + ny },
+          from: corner(-1, -1),
+          to: corner(1, -1),
           stroke: '#4b5563', strokeWidth: 1,
         },
         {
           kind: 'line',
-          from: { x: c.x - dx - nx, y: c.y - dy - ny },
-          to: { x: c.x + dx - nx, y: c.y + dy - ny },
+          from: corner(-1, 1),
+          to: corner(1, 1),
           stroke: '#4b5563', strokeWidth: 1,
         },
       ];
+      return out;
+    }
+
+    case 'boxcorner': {
+      // Eck-Traverse (CAD-8): L-foermiges Polygon (6 Punkte) aus zwei
+      // Armen (rot und rot+90) um den Eckpunkt, Breite = trussWidth.
+      const armLength = (props.armLength as number | undefined) ?? 50;
+      const bWidth = (props.trussWidth as number | undefined) ?? 29;
+      const rotDeg = (props.rotation as number | undefined) ?? 0;
+      const rad = (rotDeg * Math.PI) / 180;
+      const ux = Math.cos(rad), uy = Math.sin(rad);
+      const nx = -Math.sin(rad), ny = Math.cos(rad);
+      const v = { x: el.x, y: el.y };
+      const px = (a: number, b: number): { x: number; y: number } => ({
+        x: v.x + ux * a + nx * b,
+        y: v.y + uy * a + ny * b,
+      });
+      // L-Geometrie: Arm1 entlang +u, Arm2 entlang +n (rot+90)
+      const pts = [
+        px(0, 0),
+        px(armLength, 0),
+        px(armLength, bWidth),
+        px(bWidth, bWidth),
+        px(bWidth, armLength),
+        px(0, armLength),
+      ];
+      const strokeCol = (props.stroke as string | undefined) ?? '#9aa0a6';
+      return [{
+        kind: 'polyline',
+        points: pts,
+        close: true,
+        stroke: strokeCol,
+        strokeWidth: 2,
+      }];
     }
 
     case 'barrier': {
diff --git a/frontend/src/types/cad.types.ts b/frontend/src/types/cad.types.ts
index b535b37..6731afb 100644
--- a/frontend/src/types/cad.types.ts
+++ b/frontend/src/types/cad.types.ts
@@ -7,7 +7,7 @@ export type ElementType =
   | 'polyline' | 'text' | 'dimension' | 'block_instance' | 'chair'
   | 'seating-row' | 'seating-block' | 'table' | 'stage'
   | 'leader' | 'revcloud' | 'image'
-  | 'curtain' | 'spotlight' | 'barrier' | 'truss';
+  | 'curtain' | 'spotlight' | 'barrier' | 'truss' | 'boxcorner';
 
 export type LineType = 'solid' | 'dashed' | 'dotted';
 
diff --git a/frontend/tests/trussUpgrade.test.ts b/frontend/tests/trussUpgrade.test.ts
new file mode 100644
index 0000000..1475992
--- /dev/null
+++ b/frontend/tests/trussUpgrade.test.ts
@@ -0,0 +1,313 @@
+/**
+ * Task CAD-8 - Traversen-Upgrade:
+ * 1. Laengen-Presets 50/100/200/300 cm
+ * 2. Breite einstellbar (Standard 29 cm)
+ * 3. Rotierbares Rendering (Koerper als ROTIERTES Polygon)
+ * 4. Boxcorner (Eck-Traverse) mit magnetischem Andocken in BEIDE
+ *    Richtungen: Ecke dockt an Traversen/Ecken, Traversen docken
+ *    an Ecken-Armenden.
+ */
+import { describe, it, expect, beforeEach } from 'vitest';
+import {
+  trussTool,
+  boxCornerTool,
+  trussEndpoints,
+  boxcornerEndpoints,
+  snapTrussToDock,
+  cornerDockToDock,
+} from '../src/plugins/builtin/event-tools';
+import { CADDocument } from '../src/kernel/document/CADDocument';
+import { createInMemoryDoc } from './helpers/inMemoryDoc';
+import { elementToPrimitives } from '../src/render/pixi/elementDrawers';
+import type { CADElement, Pt } from '../src/types/cad.types';
+
+function mkCtx(elements: CADElement[] = [], options: Record<string, unknown> = {}) {
+  const { ydoc } = createInMemoryDoc();
+  const doc = new CADDocument(ydoc);
+  for (const el of elements) doc.addElement(el);
+  const statuses: string[] = [];
+  const previews: (CADElement | null)[] = [];
+  const ctx: any = {
+    doc,
+    options,
+    setStatus: (m: string) => statuses.push(m),
+    setPreview: (el: CADElement | null) => previews.push(el),
+  };
+  return { ctx, doc, statuses, previews };
+}
+
+function pe(x: number, y: number): { world: Pt } {
+  return { world: { x, y } } as never;
+}
+
+function makeTruss(id: string, x: number, y: number, length: number, rotationDeg = 0, trussWidth?: number): CADElement {
+  return {
+    id, type: 'truss', layerId: 'layer-0', x, y,
+    width: length, height: trussWidth ?? 29,
+    properties: {
+      length, rotation: rotationDeg, truss: true,
+      ...(trussWidth !== undefined ? { trussWidth } : {}),
+    },
+  } as unknown as CADElement;
+}
+
+function makeCorner(id: string, x: number, y: number, armLength = 50, rotationDeg = 0, width = 29): CADElement {
+  return {
+    id, type: 'boxcorner', layerId: 'layer-0', x, y,
+    width: 80, height: 80,
+    properties: { armLength, rotation: rotationDeg, trussWidth: width, boxcorner: true },
+  } as unknown as CADElement;
+}
+
+beforeEach(() => {
+  trussTool.handlers.cancel?.({ setStatus: () => {}, setPreview: () => {} } as never);
+  boxCornerTool.handlers.cancel?.({ setStatus: () => {}, setPreview: () => {} } as never);
+});
+
+// ─── 1: Laengen-Presets + Breite ──────────────────────────────
+
+describe('CAD-8: Laengen-Presets + Breite', () => {
+  it('Laengen-Select: genau 50/100/200/300 cm', () => {
+    const lenField = trussTool.optionsSchema?.find((f) => f.key === 'length');
+    expect(lenField).toBeDefined();
+    expect(lenField!.type).toBe('select');
+    expect((lenField!.options ?? []).map((o) => o.value)).toEqual(['50', '100', '200', '300']);
+  });
+
+  it('Breiten-Option trussWidth (number) vorhanden', () => {
+    const wField = trussTool.optionsSchema?.find((f) => f.key === 'trussWidth');
+    expect(wField).toBeDefined();
+    expect(wField!.type).toBe('number');
+  });
+
+  it('platzierte Traverse: trussWidth=29 Standard, length=200 Standard', () => {
+    const { ctx, doc } = mkCtx();
+    trussTool.handlers.down!(pe(300, 300), ctx);
+    trussTool.handlers.up!(pe(400, 300), ctx);
+    const el = doc.getAllElements()[0];
+    expect(el.properties.trussWidth).toBe(29);
+    expect(el.properties.length).toBe(200);
+  });
+
+  it('trussWidth=40 und length=300 aus Optionen uebernommen', () => {
+    const { ctx, doc } = mkCtx([], { trussWidth: 40, length: 300 });
+    trussTool.handlers.down!(pe(100, 100), ctx);
+    trussTool.handlers.up!(pe(300, 100), ctx);
+    const el = doc.getAllElements()[0];
+    expect(el.properties.trussWidth).toBe(40);
+    expect(el.properties.length).toBe(300);
+  });
+});
+
+// ─── 2: Rotierbares Truss-Rendering ───────────────────────────
+
+describe('CAD-8: Rotierbares Truss-Rendering (Polygon-Koerper)', () => {
+  it('90-Grad-Traverse: Koerperpolygon vertikal (y-Ausdehnung = Laenge, x = Breite)', () => {
+    const el = makeTruss('t1', 100, 100, 200, 90, 29);
+    const prims = elementToPrimitives(el);
+    const body = prims.find((p) => p.kind === 'polyline') as { points: Pt[]; close: boolean } | undefined;
+    expect(body).toBeDefined();
+    expect(body!.close).toBe(true);
+    expect(body!.points).toHaveLength(4);
+    const ys = body!.points.map((p) => p.y);
+    const xs = body!.points.map((p) => p.x);
+    expect(Math.max(...ys) - Math.min(...ys)).toBeCloseTo(200, 0);
+    expect(Math.max(...xs) - Math.min(...xs)).toBeCloseTo(29, 0);
+  });
+
+  it('0-Grad-Traverse: Koerperpolygon horizontal', () => {
+    const el = makeTruss('t1', 100, 100, 200, 0, 29);
+    const body = elementToPrimitives(el).find((p) => p.kind === 'polyline') as { points: Pt[] };
+    const xs = body.points.map((p) => p.x);
+    const ys = body.points.map((p) => p.y);
+    expect(Math.max(...xs) - Math.min(...xs)).toBeCloseTo(200, 0);
+    expect(Math.max(...ys) - Math.min(...ys)).toBeCloseTo(29, 0);
+  });
+
+  it('DREHBAR: Rotation aendert die Geometrie sichtbar (45 Grad diagonal)', () => {
+    const el = makeTruss('t1', 100, 100, 200, 45, 29);
+    const body = elementToPrimitives(el).find((p) => p.kind === 'polyline') as { points: Pt[] };
+    const xs = body.points.map((p) => p.x);
+    const expected = 200 * Math.cos(Math.PI / 4) + 29 * Math.sin(Math.PI / 4);
+    expect(Math.max(...xs) - Math.min(...xs)).toBeCloseTo(expected, 0);
+  });
+
+  it('Breite im Rendering: trussWidth=40 ergibt 40 Einheiten Quer-Ausdehnung', () => {
+    const el = makeTruss('t1', 100, 100, 200, 0, 40);
+    const body = elementToPrimitives(el).find((p) => p.kind === 'polyline') as { points: Pt[] };
+    const ys = body.points.map((p) => p.y);
+    expect(Math.max(...ys) - Math.min(...ys)).toBeCloseTo(40, 0);
+  });
+});
+
+// ─── 3: Boxcorner-Element ─────────────────────────────────────
+
+describe('CAD-8: Boxcorner-Element (Eck-Traverse)', () => {
+  it('Manifest: id=boxcorner, Optionen armLength + trussWidth', () => {
+    expect(boxCornerTool.manifest.id).toBe('boxcorner');
+    const keys = (boxCornerTool.optionsSchema ?? []).map((f) => f.key);
+    expect(keys).toContain('armLength');
+    expect(keys).toContain('trussWidth');
+  });
+
+  it('Drag-Platzierung: boxcorner mit armLength=50/trussWidth=29 Standard, Rotation aus Drag', () => {
+    const { ctx, doc } = mkCtx();
+    boxCornerTool.handlers.down!(pe(100, 100), ctx);
+    boxCornerTool.handlers.up!(pe(200, 100), ctx);
+    const els = doc.getAllElements();
+    expect(els).toHaveLength(1);
+    const el = els[0];
+    expect(el.type).toBe('boxcorner');
+    expect(el.properties.armLength).toBe(50);
+    expect(el.properties.trussWidth).toBe(29);
+    expect(el.properties.rotation).toBeCloseTo(0, 5);
+  });
+
+  it('Drag nach unten: Rotation ~90', () => {
+    const { ctx, doc } = mkCtx();
+    boxCornerTool.handlers.down!(pe(100, 100), ctx);
+    boxCornerTool.handlers.up!(pe(100, 200), ctx);
+    expect(doc.getAllElements()[0].properties.rotation).toBeCloseTo(90, 5);
+  });
+
+  it('Optionen uebernommen: armLength=100, trussWidth=40', () => {
+    const { ctx, doc } = mkCtx([], { armLength: 100, trussWidth: 40 });
+    boxCornerTool.handlers.down!(pe(100, 100), ctx);
+    boxCornerTool.handlers.up!(pe(200, 100), ctx);
+    const el = doc.getAllElements()[0];
+    expect(el.properties.armLength).toBe(100);
+    expect(el.properties.trussWidth).toBe(40);
+  });
+
+  it('boxcornerEndpoints: Arme bei rot und rot+90 vom Eckpunkt', () => {
+    const el = makeCorner('c1', 100, 100, 100, 0);
+    const [a1, a2] = boxcornerEndpoints(el);
+    expect(a1.x).toBeCloseTo(200, 5);
+    expect(a1.y).toBeCloseTo(100, 5);
+    expect(a2.x).toBeCloseTo(100, 5);
+    expect(a2.y).toBeCloseTo(200, 5);
+  });
+
+  it('DREHBAR: Rotation 90 dreht die Arm-Endpunkte mit', () => {
+    const el = makeCorner('c1', 100, 100, 100, 90);
+    const [a1, a2] = boxcornerEndpoints(el);
+    expect(a1.x).toBeCloseTo(100, 5);
+    expect(a1.y).toBeCloseTo(200, 5);
+    expect(a2.x).toBeCloseTo(0, 5);
+    expect(a2.y).toBeCloseTo(100, 5);
+  });
+
+  it('1 Undo entfernt die Boxcorner (EINE Transaktion)', () => {
+    const { ctx, doc } = mkCtx();
+    boxCornerTool.handlers.down!(pe(100, 100), ctx);
+    boxCornerTool.handlers.up!(pe(200, 100), ctx);
+    expect(doc.getAllElements()).toHaveLength(1);
+    doc.undo();
+    expect(doc.getAllElements()).toHaveLength(0);
+  });
+
+  it('cancel verwirft die Platzierung', () => {
+    const { ctx, doc } = mkCtx();
+    boxCornerTool.handlers.down!(pe(100, 100), ctx);
+    boxCornerTool.handlers.cancel?.(ctx);
+    boxCornerTool.handlers.up!(pe(200, 100), ctx);
+    expect(doc.getAllElements()).toHaveLength(0);
+  });
+});
+
+// ─── 4: Boxcorner-Magnetismus (beide Richtungen) ─────────────
+
+describe('CAD-8: Boxcorner-Magnetismus', () => {
+  it('cornerDockToDock: Ecke dockt an Traversen-Ende, Rotation = Weg-Richtung', () => {
+    const t1 = makeTruss('t1', 100, 100, 200, 0);
+    const dock = cornerDockToDock([t1], { x: 210, y: 105 }, 25);
+    expect(dock).not.toBeNull();
+    expect(dock!.vertex.x).toBeCloseTo(200, 5);
+    expect(dock!.vertex.y).toBeCloseTo(100, 5);
+    expect(dock!.rotationDeg).toBeCloseTo(0, 5);
+    expect(dock!.dockedTo).toBe('t1');
+  });
+
+  it('am Start-Ende der Traverse: Rotation 180 (weg von der Traverse)', () => {
+    const t1 = makeTruss('t1', 100, 100, 200, 0);
+    const dock = cornerDockToDock([t1], { x: -10, y: 98 }, 25);
+    expect(dock!.vertex.x).toBeCloseTo(0, 5);
+    expect(dock!.vertex.y).toBeCloseTo(100, 5);
+    expect(dock!.rotationDeg).toBeCloseTo(180, 5);
+  });
+
+  it('ausserhalb der Toleranz: kein Dock (null)', () => {
+    const t1 = makeTruss('t1', 100, 100, 200, 0);
+    expect(cornerDockToDock([t1], { x: 500, y: 500 }, 25)).toBeNull();
+  });
+
+  it('Traverse dockt an Boxcorner-Armende (snapTrussToDock kennt Ecken)', () => {
+    const c1 = makeCorner('c1', 100, 100, 50, 0);
+    const dock = snapTrussToDock([c1], { x: 150, y: 100 }, 200, 25);
+    expect(dock).not.toBeNull();
+    expect(dock!.rotationDeg).toBeCloseTo(0, 5);
+    expect(dock!.center.x).toBeCloseTo(250, 3);
+    expect(dock!.center.y).toBeCloseTo(100, 3);
+    expect(dock!.dockedTo).toBe('c1');
+  });
+
+  it('Ecke dockt an Ecken-Armende', () => {
+    const c1 = makeCorner('c1', 100, 100, 50, 0);
+    const dock = cornerDockToDock([c1], { x: 152, y: 102 }, 25);
+    expect(dock!.vertex.x).toBeCloseTo(150, 5);
+    expect(dock!.vertex.y).toBeCloseTo(100, 5);
+    expect(dock!.rotationDeg).toBeCloseTo(0, 5);
+    expect(dock!.dockedTo).toBe('c1');
+  });
+
+  it('Integration: platzierte Ecke wird vom trussTool magnetisch gefunden', () => {
+    const { ctx, doc } = mkCtx();
+    boxCornerTool.handlers.down!(pe(100, 100), ctx);
+    boxCornerTool.handlers.up!(pe(200, 100), ctx);
+    trussTool.handlers.down!(pe(150, 100), ctx);
+    trussTool.handlers.up!(pe(250, 100), ctx);
+    const els = doc.getAllElements();
+    expect(els).toHaveLength(2);
+    const truss = els.find((e) => e.type === 'truss')!;
+    expect(truss.properties.rotation).toBeCloseTo(0, 5);
+    expect(truss.x).toBeCloseTo(250, 3);
+    expect(truss.y).toBeCloseTo(100, 3);
+  });
+
+  it('Integration: boxCornerTool dockt an bestehender Traverse', () => {
+    const t1 = makeTruss('t1', 100, 100, 200, 0);
+    const { ctx, doc } = mkCtx([t1]);
+    boxCornerTool.handlers.down!(pe(210, 105), ctx);
+    boxCornerTool.handlers.up!(pe(300, 100), ctx);
+    const corner = doc.getAllElements().find((e) => e.type === 'boxcorner')!;
+    expect(corner).toBeDefined();
+    expect(corner.x).toBeCloseTo(200, 3);
+    expect(corner.y).toBeCloseTo(100, 3);
+    expect(corner.properties.rotation).toBeCloseTo(0, 5);
+  });
+});
+
+// ─── 5: Boxcorner-Rendering ─────────────────────────────────
+
+describe('CAD-8: Boxcorner-Rendering (L-Form)', () => {
+  it('L-foermiges Polygon: 8 Punkte, geschlossen, am Eckpunkt', () => {
+    const el = makeCorner('c1', 100, 100, 50, 0, 29);
+    const prims = elementToPrimitives(el);
+    const poly = prims.find((p) => p.kind === 'polyline') as { points: Pt[]; close: boolean };
+    expect(poly).toBeDefined();
+    expect(poly.close).toBe(true);
+    expect(poly.points).toHaveLength(6); // L-Geometrie: 6 Punkte
+    const minDist = Math.min(...poly.points.map((p) => Math.hypot(p.x - 100, p.y - 100)));
+    expect(minDist).toBeLessThanOrEqual(29);
+  });
+
+  it('Rotation 90: L-Form zeigt nach unten-links statt rechts-unten', () => {
+    const el = makeCorner('c1', 100, 100, 50, 90, 29);
+    const poly = elementToPrimitives(el).find((p) => p.kind === 'polyline') as { points: Pt[] };
+    const xs = poly.points.map((p) => p.x);
+    const ys = poly.points.map((p) => p.y);
+    // Bei rot 90: Arme zeigen nach unten (y+) und links (x-)
+    expect(Math.max(...ys)).toBeGreaterThan(140);
+    expect(Math.min(...xs)).toBeLessThan(60);
+  });
+});