diff --git a/src/commands/cmds/chamfer.test.ts b/src/commands/cmds/chamfer.test.ts
new file mode 100644
index 0000000..b874095
--- /dev/null
+++ b/src/commands/cmds/chamfer.test.ts
@@ -0,0 +1,119 @@
+/**
+ * `chamferCommand` — die Kernel-Geometrie (`chamferCorner`) ist neu (existierte
+ * bisher gar nicht, anders als filletCorner). Test: eine rechtwinklige
+ * Polylinien-Ecke wird mit einer Distanz gefast (gerader Schnitt statt Bogen).
+ */
+
+import { describe, it, expect } from "vitest";
+import { chamferCommand } from "./chamfer";
+import type { CommandContext, Project } from "../types";
+
+function project(): Project {
+  return {
+    id: "t",
+    name: "T",
+    lineStyles: [],
+    hatches: [],
+    components: [],
+    wallTypes: [],
+    drawingLevels: [
+      { id: "eg", name: "EG", kind: "floor", visible: true, locked: false, floorHeight: 2.6, cutHeight: 1.0, baseElevation: 0 },
+    ],
+    layers: [{ code: "20", name: "Zeichnung", color: "#0a0a0a", lw: 0.5, visible: true, locked: false }],
+    walls: [],
+    doors: [],
+    openings: [],
+    ceilings: [],
+    stairs: [],
+    rooms: [],
+    drawings2d: [
+      // L-förmige offene Polylinie: (0,0) → (2,0) → (2,2). Ecke bei (2,0).
+      {
+        id: "poly",
+        type: "drawing2d",
+        levelId: "eg",
+        categoryCode: "20",
+        geom: { shape: "polyline", pts: [{ x: 0, y: 0 }, { x: 2, y: 0 }, { x: 2, y: 2 }], closed: false },
+      },
+    ],
+    context: [],
+  };
+}
+
+function makeCtx(p: Project): CommandContext {
+  return {
+    project: p,
+    level: p.drawingLevels[0],
+    defaultCategoryCode: "20",
+    activeLineStyleId: "solid",
+    activeWallTypeId: "aw",
+    lastPoint: null,
+    selection: { wallIds: [], drawingId: null },
+  };
+}
+
+describe("chamferCommand", () => {
+  it("fast die Ecke mit getippter Distanz (Zahl-Eingabe)", () => {
+    const p = project();
+    const ctx = makeCtx(p);
+
+    // Schritt 1: Ecke wählen (Klick nahe (2,0)).
+    const [afterPick, r1] = chamferCommand.onInput(
+      chamferCommand.init(),
+      { kind: "point", point: { x: 2, y: 0 } },
+      ctx,
+    );
+    expect(r1.done).toBeFalsy();
+
+    // Schritt 2: Distanz getippt (0.5m) → commit.
+    const [, r2] = chamferCommand.onInput(afterPick, { kind: "number", value: 0.5 }, ctx);
+    expect(r2.done).toBe(true);
+    expect(r2.commit).toBeDefined();
+
+    const next = r2.commit!(p);
+    const poly = next.drawings2d.find((d) => d.id === "poly")!;
+    expect(poly.geom.shape).toBe("polyline");
+    if (poly.geom.shape !== "polyline") return;
+    const pts = poly.geom.pts;
+    // Die scharfe Ecke (2,0) darf nicht mehr vorkommen — durch die Fasung ersetzt.
+    expect(pts.some((p) => p.x === 2 && p.y === 0)).toBe(false);
+    // Anfangs-/Endpunkt der ganzen Kette bleiben unverändert.
+    expect(pts[0]).toEqual({ x: 0, y: 0 });
+    expect(pts[pts.length - 1]).toEqual({ x: 2, y: 2 });
+    // Exakt zwei neue Punkte (gerade Fasung, keine Tessellierung): 0.5m vom
+    // Eck entlang jedes Schenkels.
+    expect(pts.length).toBe(4);
+    const close = (a: { x: number; y: number }, x: number, y: number) =>
+      Math.hypot(a.x - x, a.y - y) < 1e-9;
+    expect(close(pts[1], 1.5, 0)).toBe(true);
+    expect(close(pts[2], 2, 0.5)).toBe(true);
+  });
+
+  it("daneben geklickt → Befehl bleibt im pick-Zustand (kein Treffer)", () => {
+    const p = project();
+    const ctx = makeCtx(p);
+    const [state, result] = chamferCommand.onInput(
+      chamferCommand.init(),
+      { kind: "point", point: { x: 50, y: 50 } },
+      ctx,
+    );
+    expect(result.commit).toBeUndefined();
+    expect(result.done).toBeFalsy();
+    expect((state as { phase: string }).phase).toBe("pick");
+  });
+
+  it("Distanz zu gross für die Schenkellänge → No-op (kein commit-Effekt)", () => {
+    const p = project();
+    const ctx = makeCtx(p);
+    const [afterPick] = chamferCommand.onInput(
+      chamferCommand.init(),
+      { kind: "point", point: { x: 2, y: 0 } },
+      ctx,
+    );
+    // Schenkel sind 2m lang; 10m Distanz passt auf keinen der beiden.
+    const [, r2] = chamferCommand.onInput(afterPick, { kind: "number", value: 10 }, ctx);
+    expect(r2.commit).toBeDefined();
+    const next = r2.commit!(p);
+    expect(next).toBe(p); // unverändert
+  });
+});
diff --git a/src/commands/cmds/chamfer.ts b/src/commands/cmds/chamfer.ts
new file mode 100644
index 0000000..9cb3f83
--- /dev/null
+++ b/src/commands/cmds/chamfer.ts
@@ -0,0 +1,210 @@
+// Chamfer — fast die Ecke einer 2D-Kurve (polyline/rect) mit einer geraden
+// Abschrägung (Rhino/AutoCAD-artig, Gegenstück zu Fillet ohne Bogen).
+// Gleicher Aufbau wie fillet.ts (siehe dort für die ausführlichere
+// Begründung), nur mit `chamferCorner` statt `filletCorner`:
+//   1) „Ecke wählen:"  → Punkt (nächstgelegener Eckpunkt einer polyline/rect)
+//   2) „Distanz:"       → Punkt (Abstand von der Ecke) ODER getippte Zahl → commit
+//
+// Anders als Fillet braucht Chamfer KEINE Bogen-Tessellierung — die Fasung
+// ist von Natur aus gerade, also ein exaktes (nicht approximiertes) Ergebnis.
+
+import type { Drawing2D, Drawing2DGeom } from "../../model/types";
+import { chamferCorner, type Chamfer } from "../../geometry/kernel2d";
+import type {
+  Command,
+  CommandContext,
+  CommandField,
+  CommandResult,
+  CommandState,
+  DraftShape,
+  Project,
+  ToolDraft,
+  Vec2,
+} from "../types";
+
+const HIT_TOL = 0.3; // Modell-Meter: Pick-Toleranz für die Eckenwahl
+const DEFAULT_DISTANCE = 0.1; // m — Startwert, bis der Nutzer per Maus/Tab einen eigenen setzt
+const EPS = 1e-6;
+const dist = (a: Vec2, b: Vec2): number => Math.hypot(b.x - a.x, b.y - a.y);
+
+interface Curve {
+  pts: Vec2[];
+  closed: boolean;
+}
+
+/** Wandelt eine chamfer-fähige 2D-Form (polyline/rect) in eine Punktliste oder null. */
+function geomToCurve(g: Drawing2DGeom): Curve | null {
+  if (g.shape === "polyline") return { pts: g.pts, closed: g.closed };
+  if (g.shape === "rect") {
+    return {
+      pts: [g.min, { x: g.max.x, y: g.min.y }, g.max, { x: g.min.x, y: g.max.y }],
+      closed: true,
+    };
+  }
+  return null; // line (keine eigene Ecke), circle/arc/text: nicht chamfer-fähig
+}
+
+/** Ein Treffer: das Element + der Eckpunkt-Index (mit gültigen beiden Nachbarn). */
+interface CornerHit {
+  drawing: Drawing2D;
+  curve: Curve;
+  index: number;
+}
+
+/** Nächster Eckpunkt (mit zwei Nachbarn) einer chamfer-fähigen Drawing2D zum Klickpunkt. */
+function pickCornerAt(project: Project, levelId: string, pt: Vec2): CornerHit | null {
+  let best: CornerHit | null = null;
+  let bestD = HIT_TOL;
+  for (const d of project.drawings2d) {
+    if (d.levelId !== levelId) continue;
+    const curve = geomToCurve(d.geom);
+    if (!curve) continue;
+    const n = curve.pts.length;
+    for (let i = 0; i < n; i++) {
+      // Offene Polylinie: die beiden Endpunkte haben keinen zweiten Nachbarn.
+      if (!curve.closed && (i === 0 || i === n - 1)) continue;
+      const dd = dist(pt, curve.pts[i]);
+      if (dd < bestD) {
+        bestD = dd;
+        best = { drawing: d, curve, index: i };
+      }
+    }
+  }
+  return best;
+}
+
+/** Fasungs-Geometrie für einen Treffer + Distanz (oder null, falls unmöglich). */
+function chamferFor(hit: CornerHit, distance: number): Chamfer | null {
+  const n = hit.curve.pts.length;
+  const prev = hit.curve.pts[(hit.index - 1 + n) % n];
+  const next = hit.curve.pts[(hit.index + 1) % n];
+  const corner = hit.curve.pts[hit.index];
+  return chamferCorner(corner, prev, next, distance);
+}
+
+/** Ersetzt den Eckpunkt durch die beiden Fasungs-Punkte (Schenkel↔Schenkel). */
+function applyChamferPoints(hit: CornerHit, c: Chamfer): Vec2[] {
+  return [
+    ...hit.curve.pts.slice(0, hit.index),
+    c.a,
+    c.b,
+    ...hit.curve.pts.slice(hit.index + 1),
+  ];
+}
+
+function chamferDraft(hit: CornerHit, d: number, at: Vec2 | null): ToolDraft {
+  const c = d > EPS ? chamferFor(hit, d) : null;
+  const preview: DraftShape[] = c ? [{ kind: "poly", pts: [c.a, c.b], closed: false }] : [];
+  const draft: ToolDraft = { preview, vertices: [hit.curve.pts[hit.index]] };
+  if (at) draft.hud = { at, text: `D: ${d.toFixed(3)}m${c ? "" : " ✗"}` };
+  return draft;
+}
+
+function commitChamfer(p: Project, hit: CornerHit, distance: number): Project {
+  const c = chamferFor(hit, distance);
+  if (!c) return p; // Distanz zu gross für die Schenkellänge, oder Ecke (fast) gerade → No-op
+  const pts = applyChamferPoints(hit, c);
+  const geom: Drawing2DGeom = { shape: "polyline", pts, closed: hit.curve.closed };
+  return {
+    ...p,
+    drawings2d: p.drawings2d.map((d) => (d.id === hit.drawing.id ? { ...d, geom } : d)),
+  };
+}
+
+// ── Zustand ───────────────────────────────────────────────────────────────────
+const DISTANCE_FIELDS: CommandField[] = [{ id: "distance", labelKey: "cmd.field.distance" }];
+
+interface ChamferPick extends CommandState {
+  phase: "pick";
+}
+interface ChamferDistance extends CommandState {
+  phase: "distance";
+  hit: CornerHit;
+  distance: number;
+}
+interface ChamferDone extends CommandState {
+  phase: "done";
+}
+type ChamferState = ChamferPick | ChamferDistance | ChamferDone;
+
+const finish = (): [CommandState, CommandResult] => [
+  { phase: "done", lastPoint: null } as ChamferDone,
+  { draft: null, done: true },
+];
+
+export const chamferCommand: Command = {
+  name: "chamfer",
+  labelKey: "cmd.chamfer.label",
+  prompt: (s) =>
+    (s as ChamferState).phase === "distance" ? "cmd.chamfer.distance" : "cmd.chamfer.pick",
+  accepts: (s) => ((s as ChamferState).phase === "distance" ? ["point", "number"] : ["point"]),
+  options: () => [],
+  fields: (s) => ((s as ChamferState).phase === "distance" ? DISTANCE_FIELDS : []),
+
+  init: (): ChamferPick => ({ phase: "pick", lastPoint: null }),
+
+  onInput: (state, input, ctx: CommandContext): [CommandState, CommandResult] => {
+    const s = state as ChamferState;
+    if (s.phase === "done") return finish();
+    if (s.phase === "pick") {
+      if (input.kind !== "point") return [s, { draft: null }];
+      const hit = pickCornerAt(ctx.project, ctx.level.id, input.point);
+      if (!hit) return [s, { draft: null }]; // daneben geklickt → aktiv bleiben
+      const next: ChamferDistance = {
+        phase: "distance",
+        hit,
+        distance: DEFAULT_DISTANCE,
+        lastPoint: input.point,
+      };
+      return [next, { draft: chamferDraft(hit, next.distance, input.point) }];
+    }
+    // phase === "distance"
+    let d = s.distance;
+    if (input.kind === "number") d = Math.max(0, input.value);
+    else if (input.kind === "point") d = Math.max(0, dist(s.hit.curve.pts[s.hit.index], input.point));
+    else return [s, { draft: null }];
+    return [
+      { phase: "done", lastPoint: null } as ChamferDone,
+      { draft: null, done: true, commit: (p) => commitChamfer(p, s.hit, d) },
+    ];
+  },
+
+  onMove: (state, point, _snap, ctx): [CommandState, CommandResult] => {
+    const s = state as ChamferState;
+    if (s.phase === "pick") {
+      const hit = pickCornerAt(ctx.project, ctx.level.id, point);
+      if (!hit) return [s, { draft: null }];
+      return [s, { draft: chamferDraft(hit, DEFAULT_DISTANCE, point) }];
+    }
+    if (s.phase !== "distance") return [s, { draft: null }];
+    const d = Math.max(0, dist(s.hit.curve.pts[s.hit.index], point));
+    const ns: ChamferDistance = { ...s, distance: d };
+    return [ns, { draft: chamferDraft(s.hit, d, point) }];
+  },
+
+  onConfirm: (): [CommandState, CommandResult] => finish(),
+  onCancel: (): [CommandState, CommandResult] => finish(),
+
+  // Tab-Feld-Zyklus nur im „distance"-Schritt, analog zu fillet.ts/circle.ts.
+  fieldValues: (state, _locks, cursor): Record<string, number> => {
+    const s = state as ChamferState;
+    if (s.phase !== "distance" || !cursor) return {};
+    return { distance: dist(s.hit.curve.pts[s.hit.index], cursor) };
+  },
+  pointFromFields: (state, locks, cursor) => {
+    const s = state as ChamferState;
+    if (s.phase !== "distance") return null;
+    const corner = s.hit.curve.pts[s.hit.index];
+    const d = "distance" in locks ? Math.max(0, locks.distance) : cursor ? dist(corner, cursor) : 0;
+    if (cursor) {
+      const dd = dist(corner, cursor);
+      if (dd > EPS) {
+        return {
+          x: corner.x + ((cursor.x - corner.x) / dd) * d,
+          y: corner.y + ((cursor.y - corner.y) / dd) * d,
+        };
+      }
+    }
+    return { x: corner.x + d, y: corner.y };
+  },
+};
diff --git a/src/commands/registry.ts b/src/commands/registry.ts
index a7bf2b8..c8e481b 100644
--- a/src/commands/registry.ts
+++ b/src/commands/registry.ts
@@ -28,6 +28,7 @@ import { extrudeCommand } from "./cmds/extrude";
 import { trimCommand } from "./cmds/trim";
 import { extendCommand } from "./cmds/extend";
 import { filletCommand } from "./cmds/fillet";
+import { chamferCommand } from "./cmds/chamfer";
 import { importCommand } from "./cmds/import";
 import { terrainCommand } from "./cmds/terrain";
 import { measureCommand } from "./cmds/measure";
@@ -62,6 +63,7 @@ export const COMMANDS: Record<string, Command> = {
   trim: trimCommand,
   extend: extendCommand,
   fillet: filletCommand,
+  chamfer: chamferCommand,
   import: importCommand,
   terrain: terrainCommand,
   measure: measureCommand,
@@ -117,6 +119,8 @@ export const ALIASES: Record<string, string> = {
   verlängern: "extend",
   fi: "fillet",
   verrunden: "fillet",
+  ch: "chamfer",
+  fasen: "chamfer",
   imp: "import",
   ter: "terrain",
   schnittlinie: "sectionline",
diff --git a/src/geometry/kernel2d.ts b/src/geometry/kernel2d.ts
index 8d52d02..3ba2619 100644
--- a/src/geometry/kernel2d.ts
+++ b/src/geometry/kernel2d.ts
@@ -572,6 +572,44 @@ export function filletCorner(
   return { center, radius: r, tangentA, tangentB, startAngle, endAngle };
 }
 
+/** Ergebnis einer Eck-Fasung. */
+export interface Chamfer {
+  /** Punkt auf dem ersten Schenkel (corner→p1), im Abstand `distance` vom Eck. */
+  a: Vec2;
+  /** Punkt auf dem zweiten Schenkel (corner→p2), im Abstand `distance` vom Eck. */
+  b: Vec2;
+}
+
+/**
+ * Fast die Ecke bei `corner` (Schenkel corner→p1, corner→p2) mit einer geraden
+ * Abschrägung: gleicher Abstand `distance` vom Eck auf BEIDEN Schenkeln,
+ * verbunden durch eine gerade Linie (klassischer Gleichabstands-Chamfer, wie
+ * `filletCorner`, nur ohne Bogen — die Ecke fällt weg, der Schnitt bleibt
+ * gerade). Liefert `null` bei (nahezu) kollinearen Schenkeln oder wenn
+ * `distance` länger als ein Schenkel ist.
+ */
+export function chamferCorner(
+  corner: Vec2,
+  p1: Vec2,
+  p2: Vec2,
+  distance: number,
+): Chamfer | null {
+  const u1 = normalize(sub(p1, corner));
+  const u2 = normalize(sub(p2, corner));
+  const cosTheta = Math.max(-1, Math.min(1, dot(u1, u2)));
+  const theta = Math.acos(cosTheta);
+  if (theta < 1e-4 || Math.PI - theta < 1e-4) return null; // kollinear
+  if (
+    distance > len(sub(p1, corner)) + EPS ||
+    distance > len(sub(p2, corner)) + EPS
+  ) {
+    return null;
+  }
+  const a = add(corner, scale(u1, distance));
+  const b = add(corner, scale(u2, distance));
+  return { a, b };
+}
+
 // ── Split / Join / Segment-Löschen (Drawing2D-Editieren) ─────────────────────
 // Reine Geometrie auf Polylinien (`Vec2[]` + `closed`). Die Operations-Schicht
 // (`src/editors/splitJoin.ts`) wandelt Drawing2D ↔ {pts, closed} und ruft diese
diff --git a/src/i18n/de.ts b/src/i18n/de.ts
index 0d4b16b..f1b13b4 100644
--- a/src/i18n/de.ts
+++ b/src/i18n/de.ts
@@ -1189,6 +1189,10 @@ export const de = {
   "cmd.fillet.label": "Verrunden",
   "cmd.fillet.pick": "Ecke wählen:",
   "cmd.fillet.radius": "Radius:",
+  // Chamfer: Eckpunkt-Fasung mit Distanz (Maus oder getippt) — wie Fillet, ohne Bogen.
+  "cmd.chamfer.label": "Fasen",
+  "cmd.chamfer.pick": "Ecke wählen:",
+  "cmd.chamfer.distance": "Distanz:",
   // Editier-Werkzeuge Split / Join / Segment-Löschen (Tastatur: Ctrl+S / Ctrl+J /
   // Alt+Klick). Labels für Befehlsleiste/Menüs.
   "edit.split.label": "Teilen",
diff --git a/src/i18n/en.ts b/src/i18n/en.ts
index 10cee85..e50f384 100644
--- a/src/i18n/en.ts
+++ b/src/i18n/en.ts
@@ -1177,6 +1177,10 @@ export const en: Record<TranslationKey, string> = {
   "cmd.fillet.label": "Fillet",
   "cmd.fillet.pick": "Select corner:",
   "cmd.fillet.radius": "Radius:",
+  // Chamfer: corner bevel with a distance (mouse or typed) — like Fillet, no arc.
+  "cmd.chamfer.label": "Chamfer",
+  "cmd.chamfer.pick": "Select corner:",
+  "cmd.chamfer.distance": "Distance:",
   // Edit tools Split / Join / Delete segment (keyboard: Ctrl+S / Ctrl+J /
   // Alt+Click). Labels for the command line / menus.
   "edit.split.label": "Split",
diff --git a/src/panels/ToolsPanel.tsx b/src/panels/ToolsPanel.tsx
index 30b4f47..1a6d617 100644
--- a/src/panels/ToolsPanel.tsx
+++ b/src/panels/ToolsPanel.tsx
@@ -177,7 +177,7 @@ export function ToolIcon({ id }: { id: ToolId }) {
 const TOOLS_2D: ToolId[] = ["line", "polyline", "rect", "circle", "arc", "text", "textbox", "image"];
 const TOOLS_3D: ToolId[] = ["wall", "ceiling", "window", "door", "stair", "room"];
 const COMMANDS_3D = ["column", "ceilingopening", "roof", "extrude", "sectionline", "viewline"];
-const COMMANDS_EDIT = ["move", "copy", "rotate", "mirror", "offset", "trim", "extend", "fillet", "join", "measure"];
+const COMMANDS_EDIT = ["move", "copy", "rotate", "mirror", "offset", "trim", "extend", "fillet", "chamfer", "join", "measure"];
 
 type ToolsView = "list" | "icons";
 const VIEW_STORAGE_KEY = "dossier.toolsPanel.view";
diff --git a/src/ui/ribbon/CommandIcon.tsx b/src/ui/ribbon/CommandIcon.tsx
index 3dd5365..c568beb 100644
--- a/src/ui/ribbon/CommandIcon.tsx
+++ b/src/ui/ribbon/CommandIcon.tsx
@@ -98,6 +98,13 @@ export function CommandIcon({ name }: { name: string }) {
           <path d="M3,13 L3,8 Q3,3 8,3 L13,3" />
         </svg>
       );
+    case "chamfer":
+      // Eckpunkt-Fasung: gerade Schenkel, Ecke durch eine gerade Schräge ersetzt.
+      return (
+        <svg {...common}>
+          <path d="M3,13 L3,6 L6,3 L13,3" />
+        </svg>
+      );
     case "extend":
       // Linie, die bis zu einer Grenze verlängert wird (Pfeil + Ziellinie).
       return (