# Recovery

> Recover unsaved canvas work after a crash or refresh. The engine copies edits to IndexedDB while the user works and offers them back on the next start.

Source: https://fabricjs-document-engine.jscrate.dev/docs/guides/recovery
Last updated: 2026-09-28

Autosave waits for a pause, and a save can fail. Recovery covers the gap: the engine keeps a local copy of unsaved work, so you can recover unsaved canvas work after a crash, a refresh or a closed tab.

```tsx
"use client";

import type { RecoveryRecord } from "fabricjs-document-engine";
import {
  useDocumentEngine,
  useDocumentState,
} from "fabricjs-document-engine/react";
import { createMemoryRecovery } from "fabricjs-document-engine/recovery";
import { createMemoryStorage } from "fabricjs-document-engine/storage";
import { CircleIcon, SquareIcon, ZapIcon } from "lucide-react";
import { useFormatter, useTranslations } from "next-intl";
import { useEffect, useState } from "react";

import {
  DemoCanvas,
  DemoFrame,
  newShape,
  seedShapes,
  Status,
  Toolbar,
  ToolButton,
} from "./demo-ui";
import { useFabricCanvas } from "./use-fabric-canvas";

// In your app, use `createIndexedDbRecovery()` so copies survive a reload.
// Memory keeps this demo self-contained.
const storage = createMemoryStorage();
const recovery = { store: createMemoryRecovery(), interval: 500 };

function Editor({ fresh, onCrash }: { fresh: boolean; onCrash: () => void }) {
  const t = useTranslations("demos");
  const format = useFormatter();
  const { elementRef, canvas } = useFabricCanvas();
  const engine = useDocumentEngine(canvas, {
    storage,
    recovery,
    document: { id: "recovery-demo" },
  });
  const state = useDocumentState(engine);
  const [copy, setCopy] = useState<RecoveryRecord>();

  // The first session starts with a drawing that was never saved. After a
  // crash the editor opens empty and looks for the work it lost.
  useEffect(() => {
    if (!engine) return;
    if (fresh) engine.canvas.add(...seedShapes());
    engine.getRecoverableDocuments().then(([latest]) => setCopy(latest));
  }, [engine, fresh]);

  async function restore() {
    await engine?.restoreRecovery(copy?.documentId);
    setCopy(undefined);
  }

  async function discard() {
    await engine?.discardRecovery(copy?.documentId);
    setCopy(undefined);
  }

  return (
    <DemoFrame>
      <DemoCanvas elementRef={elementRef} label={t("canvas")}>
        {copy && (
          <div
            role="alert"
            className="absolute inset-x-2 bottom-2 flex items-center gap-2 rounded-md border bg-background/95 p-1.5 pl-3 text-[13px] shadow-sm backdrop-blur"
          >
            <span className="truncate">
              {t("recovery.found", {
                time: format.dateTime(new Date(copy.savedAt), {
                  timeStyle: "medium",
                }),
              })}
            </span>
            <button
              type="button"
              className="ml-auto h-7 shrink-0 rounded-md px-2 font-medium hover:bg-muted"
              onClick={() => void discard()}
            >
              {t("recovery.discard")}
            </button>
            <button
              type="button"
              className="h-7 shrink-0 rounded-md bg-foreground px-2.5 font-medium text-background hover:bg-foreground/85"
              onClick={() => void restore()}
            >
              {t("recovery.restore")}
            </button>
          </div>
        )}
      </DemoCanvas>

      <Toolbar>
        <ToolButton
          icon={SquareIcon}
          label={t("square")}
          onClick={() => canvas?.add(newShape("square"))}
        />
        <ToolButton
          icon={CircleIcon}
          label={t("circle")}
          onClick={() => canvas?.add(newShape("circle"))}
        />
        <ToolButton
          icon={ZapIcon}
          label={t("recovery.crash")}
          className="ml-auto"
          disabled={!state?.isDirty}
          onClick={onCrash}
        />
      </Toolbar>

      <Status tone={copy ? "error" : state?.isDirty ? "busy" : "ok"}>
        {copy
          ? t("recovery.crashed")
          : state?.isDirty
            ? t("recovery.unsaved")
            : t("recovery.saved")}
      </Status>
    </DemoFrame>
  );
}

export default function RecoveryDemo() {
  // A new key throws the editor away without saving, like a closed tab.
  const [session, setSession] = useState(0);

  return (
    <Editor
      key={session}
      fresh={session === 0}
      onCrash={() => setSession((n) => n + 1)}
    />
  );
}
```

```tsx
import { Canvas } from "fabric";
import { useLayoutEffect, useRef, useState } from "react";

/**
 * The page every demo draws on. The document keeps this size; CSS scales the
 * canvas down to fit its card, so saved documents and exports never depend on
 * the screen.
 */
export const PAGE = { width: 480, height: 300 };

// Selection handles in the site's style. Fabric does not save these.
const SELECTION = {
  borderColor: "#6f00ff",
  borderScaleFactor: 1.5,
  borderOpacityWhenMoving: 0.5,
  cornerStyle: "circle",
  cornerSize: 11,
  cornerColor: "#ffffff",
  cornerStrokeColor: "#6f00ff",
  transparentCorners: false,
} as const;

export function styleSelection(canvas: Canvas) {
  canvas.set({
    selectionColor: "rgba(111, 0, 255, 0.06)",
    selectionBorderColor: "#6f00ff",
    selectionLineWidth: 1,
  });
  const style = () => canvas.getActiveObject()?.set(SELECTION);
  canvas.on("selection:created", style);
  canvas.on("selection:updated", style);
}

/**
 * Creates a Fabric.js canvas once the `<canvas>` element exists, and disposes
 * it on unmount. The engine is created from the returned `canvas`.
 */
export function useFabricCanvas({ width, height } = PAGE) {
  const elementRef = useRef<HTMLCanvasElement>(null);
  const [canvas, setCanvas] = useState<Canvas | null>(null);

  // A layout effect creates the canvas before the first paint.
  useLayoutEffect(() => {
    const created = new Canvas(elementRef.current!, {
      width,
      height,
      backgroundColor: "#ffffff",
    });
    styleSelection(created);
    setCanvas(created);

    return () => {
      // Dispose after the engine's own cleanup, so its last recovery copy
      // still sees the objects.
      setTimeout(() => created.dispose().catch(() => undefined));
    };
  }, [width, height]);

  return { elementRef, canvas };
}
```

```tsx
import { Circle, type FabricObject, Rect, Triangle } from "fabric";
import type { LucideIcon } from "lucide-react";

import { cn } from "@/lib/utils";

import { PAGE } from "./use-fabric-canvas";

export const COLORS = ["#f2836f", "#5fe6c4", "#7ad9ec", "#6f00ff", "#ffd666"];

// Demo shapes are placed by their top-left corner, like a design tool.
const CORNER = { originX: "left", originY: "top" } as const;

/** A new shape at a random spot on the page. */
export function newShape(kind: "square" | "circle", fill?: string) {
  const left = 40 + Math.random() * (PAGE.width - 160);
  const top = 30 + Math.random() * (PAGE.height - 120);
  const color = fill ?? COLORS[Math.floor(Math.random() * COLORS.length)];
  return kind === "square"
    ? new Rect({
        ...CORNER,
        left,
        top,
        width: 88,
        height: 64,
        rx: 10,
        ry: 10,
        fill: color,
      })
    : new Circle({ ...CORNER, left, top, radius: 34, fill: color });
}

/** A small composed drawing, so no demo starts on an empty page. */
export function seedShapes(): FabricObject[] {
  return [
    new Rect({
      ...CORNER,
      left: 48,
      top: 56,
      width: 176,
      height: 124,
      rx: 16,
      ry: 16,
      fill: COLORS[4],
    }),
    new Circle({ ...CORNER, left: 268, top: 44, radius: 58, fill: COLORS[0] }),
    new Rect({
      ...CORNER,
      left: 256,
      top: 196,
      width: 176,
      height: 52,
      rx: 26,
      ry: 26,
      fill: COLORS[1],
    }),
    new Triangle({
      ...CORNER,
      left: 96,
      top: 196,
      width: 72,
      height: 60,
      fill: COLORS[3],
    }),
  ];
}

export function DemoFrame({
  className,
  ...props
}: React.ComponentProps<"div">) {
  return (
    <div
      className={cn(
        "flex w-full max-w-md flex-col gap-3 text-left outline-none",
        className
      )}
      {...props}
    />
  );
}

/**
 * Scales the fixed-size Fabric canvas to the frame's width. The rules are
 * `!important` because Fabric writes its sizes as inline styles.
 */
export function DemoCanvas({
  elementRef,
  label,
  page = PAGE,
  children,
}: {
  elementRef: React.Ref<HTMLCanvasElement>;
  label: string;
  page?: { width: number; height: number };
  children?: React.ReactNode;
}) {
  return (
    <div
      className="relative overflow-hidden rounded-lg border bg-white shadow-xs [&_.canvas-container]:aspect-(--page)! [&_.canvas-container]:h-auto! [&_.canvas-container]:w-full! [&_canvas]:h-full! [&_canvas]:w-full!"
      style={
        { "--page": `${page.width} / ${page.height}` } as React.CSSProperties
      }
    >
      <div>
        <canvas ref={elementRef} aria-label={label} />
      </div>
      {children}
    </div>
  );
}

export function Toolbar({ className, ...props }: React.ComponentProps<"div">) {
  return (
    <div
      className={cn("flex flex-wrap items-center gap-1.5", className)}
      {...props}
    />
  );
}

export function ToolButton({
  icon: Icon,
  label,
  iconOnly = false,
  primary = false,
  className,
  ...props
}: React.ComponentProps<"button"> & {
  icon: LucideIcon;
  label: string;
  iconOnly?: boolean;
  primary?: boolean;
}) {
  return (
    <button
      type="button"
      title={label}
      aria-label={iconOnly ? label : undefined}
      className={cn(
        "inline-flex h-8 min-w-0 items-center justify-center gap-1.5 rounded-md border px-2.5 text-[13px] font-medium whitespace-nowrap transition-colors disabled:pointer-events-none disabled:opacity-40 [&_svg]:size-3.5 [&_svg]:shrink-0",
        primary
          ? "border-transparent bg-foreground text-background hover:bg-foreground/85"
          : "bg-background hover:bg-muted",
        iconOnly && "w-8 px-0",
        className
      )}
      {...props}
    >
      <Icon aria-hidden />
      {!iconOnly && <span className="truncate">{label}</span>}
    </button>
  );
}

const TONES = {
  idle: "bg-zinc-400",
  busy: "bg-amber-400",
  ok: "bg-emerald-500",
  error: "bg-red-500",
};

/** One line of status text. Its height never changes, so the card never jumps. */
export function Status({
  tone = "idle",
  children,
}: {
  tone?: keyof typeof TONES;
  children: React.ReactNode;
}) {
  return (
    <p
      role="status"
      className="flex h-5 min-w-0 items-center gap-2 text-[13px] text-muted-foreground"
    >
      <span
        aria-hidden
        className={cn("size-1.5 shrink-0 rounded-full", TONES[tone])}
      />
      <span className="truncate">{children}</span>
    </p>
  );
}
```

## Turn it on

```ts
import { createIndexedDbRecovery } from "fabricjs-document-engine/recovery";

const engine = createDocumentEngine({
  canvas,
  storage,
  recovery: { store: createIndexedDbRecovery(), interval: 2000 },
});
```

## Offer the copy on start

```ts
const [latest] = await engine.getRecoverableDocuments();

if (
  latest &&
  confirm(
    `Restore unsaved work from ${new Date(latest.savedAt).toLocaleString()}?`
  )
) {
  await engine.restoreRecovery(latest.documentId);
} else if (latest) {
  await engine.discardRecovery(latest.documentId);
}
```

## How copies are written

- **While editing.** With unsaved changes, a copy is written to IndexedDB at most once every `interval` milliseconds. Nothing is written while the document is saved.
- **On close or refresh.** Browsers do not let IndexedDB finish while a page unloads. So when the tab is hidden or closed, the engine also writes an instant copy to localStorage. The newest copy wins.
- **Tab-only images.** Images with `blob:` URLs vanish on refresh. Copies keep the image data, and restoring creates new URLs for it.
- **After a save.** When a save covers every change, the copy is removed. If the tab closes during a save, the copy stays.

## Restoring is safe

The restored document is marked as unsaved and keeps the revision it was based on. If the server moved on in the meantime, the next save reports a [save conflict](https://fabricjs-document-engine.jscrate.dev/docs/guides/save-conflicts) instead of overwriting newer work.

## A load that crashes the tab

If a document crashes the tab while it loads, the next start could crash again. The engine keeps a marker during each load:

```ts
const interrupted = await engine.getInterruptedLoad();
if (interrupted) {
  // Ask before opening interrupted.documentId again.
}
```

## Other stores

`createMemoryRecovery()` keeps copies in memory, which is useful in tests. To recover unsaved canvas work from your own storage, implement `{ get, set, delete, keys }`, plus an optional synchronous `setNow` for the moment the page closes. See the [recovery API](https://fabricjs-document-engine.jscrate.dev/docs/api/recovery-api).