diff --git a/frontend/src/interaction/dispatcher.ts b/frontend/src/interaction/dispatcher.ts
index 5860f7a..1c3bc05 100644
--- a/frontend/src/interaction/dispatcher.ts
+++ b/frontend/src/interaction/dispatcher.ts
@@ -25,6 +25,10 @@ export interface DispatcherDeps {
   setPreview?(el: unknown | null): void;
   /** Tool-Nachschlag überschreibbar (Default: aktive Registry-Tools). */
   toolLookup?(toolId: string): ToolExtensionV2 | undefined;
+  /** Dokument-Fassade für Tools (ab A3; lazy pro Event abgefragt). */
+  getDoc?(): import('../kernel/document/CADDocument').CADDocument | undefined;
+  /** Selektions-Bridge für Tools (ab A3; lazy pro Event abgefragt). */
+  getSelectionBridge?(): import('../plugins/types').ToolSelectionBridge;
 }
 
 export class InteractionDispatcher {
@@ -91,12 +95,14 @@ export class InteractionDispatcher {
     this.bound = true;
   }
 
-  private buildContext(): ToolContext {
+  private buildContext(): import('../plugins/types').FullToolContext {
     const toolId = this.active?.manifest.id ?? '';
     return {
       options: this.deps.getOptions?.(toolId) ?? {},
       setStatus: (msg) => this.setStatus(msg),
       setPreview: (el) => this.deps.setPreview?.(el),
+      doc: this.deps.getDoc?.(),
+      selection: this.deps.getSelectionBridge?.(),
     };
   }
 
diff --git a/frontend/src/plugins/builtin/core-drawing/index.ts b/frontend/src/plugins/builtin/core-drawing/index.ts
new file mode 100644
index 0000000..b94538d
--- /dev/null
+++ b/frontend/src/plugins/builtin/core-drawing/index.ts
@@ -0,0 +1,95 @@
+/**
+ * core-drawing – Built-in V2-Plugin (Task A3 Pilot).
+ *
+ * Werkzeuge: line (Migrations-Pilot aus dem Legacy-Switch).
+ * Elemente werden über CADDocument committed → kollaborativ korrektes Undo.
+ *
+ * Sitzungszustand (Startpunkt der aktuellen Linie) lebt als Modul-Member,
+ * NICHT in options: Options sind geteilter UI-Store-Zustand.
+ */
+import type { PluginV2, ToolExtensionV2, FullToolContext } from '../../types';
+import type { CADElement } from '../../../types/cad.types';
+import type { Pt } from '../../../tools/modification/geometry';
+
+const uid = (prefix: string): string =>
+  `${prefix}_${Date.now().toString(36)}_${Math.random().toString(36).slice(2, 9)}`;
+
+/** Startpunkt der laufenden Linie (nur innerhalb einer down→up-Sitzung gesetzt). */
+let lineStart: Pt | null = null;
+
+function buildLine(start: Pt, end: Pt, ctx: FullToolContext): CADElement {
+  const stroke = (ctx.options.strokeColor as string | undefined) ?? '#e0e0f0';
+  const layerId = (ctx.options.layerId as string | undefined) ?? 'layer-0';
+  return {
+    id: uid('line'),
+    type: 'line',
+    layerId,
+    x: (start.x + end.x) / 2,
+    y: (start.y + end.y) / 2,
+    width: Math.abs(end.x - start.x),
+    height: Math.abs(end.y - start.y),
+    properties: { x1: start.x, y1: start.y, x2: end.x, y2: end.y, stroke, strokeWidth: 1 },
+  } as unknown as CADElement;
+}
+
+/**
+ * line-Werkzeug: down setzt Startpunkt, move zeigt Live-Vorschau,
+ * up committet via doc.transact (1 Linie = 1 Undo-Schritt).
+ */
+export const lineTool: ToolExtensionV2 = {
+  manifest: {
+    id: 'line',
+    label: 'Linie',
+    icon: '\u2571',
+    ribbonTab: 'canvas',
+    tags: ['basic'],
+    description: 'Zeichnet eine Linie (Klick Start, Klick Ende)',
+  },
+  optionsSchema: [
+    { key: 'strokeColor', label: 'Farbe', type: 'color' },
+  ],
+  handlers: {
+    down(e, ctx) {
+      lineStart = e.world;
+      ctx.setStatus(`Linie ab (${lineStart.x.toFixed(0)}, ${lineStart.y.toFixed(0)}) – Ende wählen`);
+    },
+    move(e, ctx) {
+      if (!lineStart) return;
+      ctx.setPreview?.(buildLine(lineStart, e.world, ctx));
+    },
+    up(e, ctx) {
+      const c = ctx as FullToolContext;
+      if (!lineStart || !c.doc) {
+        lineStart = null;
+        return;
+      }
+      const el = buildLine(lineStart, e.world, c);
+      c.doc.transact(() => {
+        // addElement öffnet inneres transact — Yjs verschachtelt sie → EIN Undo-Schritt
+        c.doc!.addElement(el);
+      });
+      lineStart = null;
+      ctx.setPreview?.(null);
+      ctx.setStatus(`Linie erstellt (${el.id})`);
+    },
+    cancel(ctx) {
+      lineStart = null;
+      ctx.setPreview?.(null);
+      ctx.setStatus('Linie abgebrochen');
+    },
+  },
+};
+
+/** V2-Plugin: Kern-Zeichenwerkzeuge (Pilot: nur line). */
+export const coreDrawingPlugin: PluginV2 = {
+  manifest: {
+    id: 'core-drawing',
+    name: 'Zeichnen (Kern)',
+    version: '1.0.0',
+    author: 'web-cad team',
+    description: 'Grundlegende Zeichenwerkzeuge (V2-Pilot: Linie).',
+    category: 'tools',
+    enabledByDefault: true,
+  },
+  tools: [lineTool],
+};
diff --git a/frontend/src/plugins/builtin/core-modify/index.ts b/frontend/src/plugins/builtin/core-modify/index.ts
new file mode 100644
index 0000000..126db53
--- /dev/null
+++ b/frontend/src/plugins/builtin/core-modify/index.ts
@@ -0,0 +1,63 @@
+/**
+ * core-modify – Built-in V2-Plugin (Task A3 Pilot).
+ *
+ * Werkzeuge: select (Pilotportierung aus Legacy handleSelectDown).
+ * Pilot-Scope: Klick-Auswahl inkl. Group-Bewusstheit via SelectionBridge;
+ * Marquee/Box-Auswahl Migration folgt in A4 (Legacy bleibt parallel aktiv).
+ */
+import type { PluginV2, ToolExtensionV2 } from '../../types';
+
+/**
+ * select-Werkzeug: Klick wählt Element direkt (Shift=additiv, Ctrl=subtraktiv).
+ */
+export const selectTool: ToolExtensionV2 = {
+  manifest: {
+    id: 'select',
+    label: 'Auswahl',
+    icon: '\u2196',
+    ribbonTab: 'canvas',
+    tags: ['basic'],
+    description: 'Elemente anklicken zum Auswählen',
+  },
+  optionsSchema: [],
+  handlers: {
+    down(e, ctx) {
+      const bridge = (ctx as import('../../types').FullToolContext).selection;
+      if (!bridge) return;
+
+      const additive = e.shift;
+      const subtractive = e.ctrl;
+      const hit = bridge.hitTest(e.world.x, e.world.y, 5);
+
+      if (!hit) {
+        // Leerer Klick: Selektion leeren (außer additiv)
+        if (!additive && !subtractive) bridge.setIds([]);
+        return;
+      }
+
+      let ids = new Set(bridge.getIds());
+      if (subtractive) {
+        ids.delete(hit.id);
+      } else {
+        ids.add(hit.id);
+        if (!additive) ids = new Set([hit.id]); // ohne Shift: nur das getroffene
+      }
+      bridge.setIds(Array.from(ids));
+      ctx.setStatus(`Selektion: ${ids.size} Element(e)`);
+    },
+  },
+};
+
+/** V2-Plugin: Kern-Bearbeitungswerkzeuge (Pilot: nur select). */
+export const coreModifyPlugin: PluginV2 = {
+  manifest: {
+    id: 'core-modify',
+    name: 'Bearbeiten (Kern)',
+    version: '1.0.0',
+    author: 'web-cad team',
+    description: 'Auswahl und Bearbeitung (V2-Pilot: Selektion).',
+    category: 'tools',
+    enabledByDefault: true,
+  },
+  tools: [selectTool],
+};
diff --git a/frontend/src/plugins/index.ts b/frontend/src/plugins/index.ts
index 31712a2..f5787b8 100644
--- a/frontend/src/plugins/index.ts
+++ b/frontend/src/plugins/index.ts
@@ -27,11 +27,18 @@ export type {
 
 // Built-in plugins
 export { eventToolsPlugin } from './builtin/eventTools';
+export { coreDrawingPlugin } from './builtin/core-drawing';
+export { coreModifyPlugin } from './builtin/core-modify';
 
 import { pluginRegistry } from './PluginRegistry';
 import { eventToolsPlugin } from './builtin/eventTools';
+import { coreDrawingPlugin } from './builtin/core-drawing';
+import { coreModifyPlugin } from './builtin/core-modify';
 
 /** Register all built-in plugins */
 export function registerBuiltinPlugins() {
   pluginRegistry.register(eventToolsPlugin);
+  // API v2 (Task A3):
+  pluginRegistry.registerV2(coreDrawingPlugin);
+  pluginRegistry.registerV2(coreModifyPlugin);
 }
diff --git a/frontend/src/plugins/types.ts b/frontend/src/plugins/types.ts
index a692aa1..f6e7139 100644
--- a/frontend/src/plugins/types.ts
+++ b/frontend/src/plugins/types.ts
@@ -153,6 +153,24 @@ export interface ToolContext {
   setPreview?(el: CADElement | null): void;
 }
 
+/** Selektions-/Treffer-Bridge für Werkzeuge (ab A3, von CanvasArea injiziert). */
+export interface ToolSelectionBridge {
+  /** Aktuell selektierte Element-IDs. */
+  getIds(): string[];
+  /** Setzt die Selektion vollständig. */
+  setIds(ids: string[]): void;
+  /** Element-Treffer an Weltposition (oder null). */
+  hitTest(worldX: number, worldY: number, tolerancePx: number): CADElement | null;
+}
+
+/** Erweiterter Kontext für Tools mit Dokument-/Selektionszugriff (A3). */
+export interface FullToolContext extends ToolContext {
+  /** Dokumentzugriff (transact/add/update/delete). */
+  doc?: import('../kernel/document/CADDocument').CADDocument;
+  /** Selektion + HitTest-Bridge. */
+  selection?: ToolSelectionBridge;
+}
+
 /** V2-Werkzeug mit eigenen Pointer-Handlern (ersetzt langfristig ToolExtension). */
 export interface ToolExtensionV2 {
   manifest: ToolManifestPart & { description?: string };
diff --git a/frontend/tests/pilotTools.test.ts b/frontend/tests/pilotTools.test.ts
new file mode 100644
index 0000000..c4d9bb4
--- /dev/null
+++ b/frontend/tests/pilotTools.test.ts
@@ -0,0 +1,150 @@
+/**
+ * Pilot V2-Tools Tests (Task A3): line + select.
+ * line: Handler-Sequenz gegen echtes CADDocument (In-Memory), Undo-Verhalten.
+ * select: Bridge-basierte Auswahl mit Shift/Ctrl.
+ */
+import { describe, it, expect, vi } from 'vitest';
+import { lineTool, coreDrawingPlugin } from '../src/plugins/builtin/core-drawing';
+import { selectTool, coreModifyPlugin } from '../src/plugins/builtin/core-modify';
+import { CADDocument } from '../src/kernel/document/CADDocument';
+import { createInMemoryDoc } from './helpers/inMemoryDoc';
+import type { ToolPointerEvent, FullToolContext } from '../src/plugins/types';
+import type { CADElement } from '../src/types/cad.types';
+
+function pe(x: number, y: number, mods: Partial<Pick<ToolPointerEvent, 'shift' | 'ctrl'>> = {}): ToolPointerEvent {
+  return {
+    world: { x, y },
+    screen: { x: x / 2, y: y / 2 },
+    button: 0,
+    shift: mods.shift ?? false,
+    alt: false,
+    ctrl: mods.ctrl ?? false,
+  };
+}
+
+function makeCtx(overrides: Partial<FullToolContext> = {}): FullToolContext & { previews: (CADElement | null)[]; statuses: string[] } {
+  const previews: (CADElement | null)[] = [];
+  const statuses: string[] = [];
+  return {
+    options: {},
+    setStatus: (m) => statuses.push(m),
+    setPreview: (el) => previews.push(el),
+    previews,
+    statuses,
+    ...overrides,
+  } as FullToolContext & { previews: (CADElement | null)[]; statuses: string[] };
+}
+
+function makeEl(id: string): CADElement {
+  return { id, type: 'rect', layerId: 'l', x: 0, y: 0, width: 1, height: 1, properties: {} } as unknown as CADElement;
+}
+
+describe('A3 pilot: line tool', () => {
+  it('erzeugt EINE Linie per down→up; ein undo entfernt sie', () => {
+    const { ydoc } = createInMemoryDoc();
+    const doc = new CADDocument(ydoc);
+    const ctx = makeCtx({ doc });
+
+    lineTool.handlers.down!(pe(0, 0), ctx);
+    lineTool.handlers.move!(pe(100, 50), ctx);
+    expect(ctx.previews.length).toBe(1);       // Live-Vorschau war da
+    lineTool.handlers.up!(pe(100, 50), ctx);
+
+    const all = doc.getAllElements();
+    expect(all.length).toBe(1);
+    expect(all[0].type).toBe('line');
+    expect(all[0].properties.x1).toBe(0);
+    expect(all[0].properties.y2).toBe(50);
+
+    // Kern-Akzeptanz aus ROADMAP: Ein Werkzeug-Klick = ein Undo-Schritt
+    expect(doc.undo()).toBe(true);
+    expect(doc.getAllElements().length).toBe(0);
+  });
+
+  it('cancel verwirft die laufende Linie ohne Element', () => {
+    const { ydoc } = createInMemoryDoc();
+    const doc = new CADDocument(ydoc);
+    const ctx = makeCtx({ doc });
+
+    lineTool.handlers.down!(pe(5, 5), ctx);
+    lineTool.handlers.cancel!(ctx);
+    lineTool.handlers.up!(pe(9, 9), ctx);      // up nach cancel: kein Start mehr
+
+    expect(doc.getAllElements().length).toBe(0);
+  });
+
+  it('Plugin-Manifest ist registrierbar und tagged basic', () => {
+    expect(coreDrawingPlugin.manifest.enabledByDefault).toBe(true);
+    const line = coreDrawingPlugin.tools?.find((t) => t.manifest.id === 'line');
+    expect(line?.manifest.tags).toContain('basic');
+  });
+});
+
+describe('A3 pilot: select tool', () => {
+  function makeBridge(elements: CADElement[]) {
+    let ids: string[] = [];
+    return {
+      bridge: {
+        getIds: () => ids,
+        setIds: (next: string[]) => {
+          ids = next;
+        },
+        hitTest: (wx: number, wy: number, tol: number): CADElement | null =>
+          elements.find((el) => Math.abs(el.x - wx) <= tol && Math.abs(el.y - wy) <= tol) ?? null,
+      },
+      getIds: () => ids,
+    };
+  }
+
+  it('wählt getroffenes Element ohne Modifier exklusiv', () => {
+    const els = [makeEl('a'), makeEl('b')];
+    els[0].x = 10; els[0].y = 10;
+    els[1].x = 500; els[1].y = 500;
+    const { bridge, getIds } = makeBridge(els);
+    const ctx = makeCtx({ selection: bridge });
+
+    selectTool.handlers.down!(pe(10, 10), ctx);
+    expect(getIds()).toEqual(['a']);
+
+    // Klick auf b ohne Shift ersetzt Selektion
+    selectTool.handlers.down!(pe(500, 500), ctx);
+    expect(getIds()).toEqual(['b']);
+  });
+
+  it('Shift addiert, Ctrl subtrahiert', () => {
+    const els = [makeEl('a'), makeEl('b'), makeEl('c')];
+    els[0].x = 10; els[0].y = 10;
+    els[1].x = 50; els[1].y = 50;
+    els[2].x = 90; els[2].y = 90;
+    const { bridge, getIds } = makeBridge(els);
+    const ctx = makeCtx({ selection: bridge });
+
+    selectTool.handlers.down!(pe(10, 10), ctx);
+    expect(getIds()).toEqual(['a']);
+
+    selectTool.handlers.down!(pe(50, 50, { shift: true }), ctx);
+    expect(getIds().sort()).toEqual(['a', 'b']);
+
+    selectTool.handlers.down!(pe(90, 90, { shift: true }), ctx);
+    expect(getIds().sort()).toEqual(['a', 'b', 'c']);
+
+    selectTool.handlers.down!(pe(50, 50, { ctrl: true }), ctx);
+    expect(getIds().sort()).toEqual(['a', 'c']);
+  });
+
+  it('Leerklick ohne Modifier leert die Selektion; Plugin tagged basic', () => {
+    const els = [makeEl('a')];
+    els[0].x = 10; els[0].y = 10;
+    const { bridge, getIds } = makeBridge(els);
+    const ctx = makeCtx({ selection: bridge });
+
+    selectTool.handlers.down!(pe(10, 10), ctx);
+    expect(getIds()).toEqual(['a']);
+    selectTool.handlers.down!(pe(999, 999), ctx);
+    expect(getIds()).toEqual([]);
+
+    expect(coreModifyPlugin.manifest.enabledByDefault).toBe(true);
+    const sel = coreModifyPlugin.tools?.find((t) => t.manifest.id === 'select');
+    expect(sel?.manifest.tags).toContain('basic');
+  });
+});