diff --git a/tools/revert-update/index.ts b/tools/revert-update/index.ts
new file mode 100644
index 0000000000..f9052a7bee
--- /dev/null
+++ b/tools/revert-update/index.ts
@@ -0,0 +1,180 @@
+import { readFileSync, writeFileSync } from 'node:fs';
+
+import {
+  applyUpdate,
+  Doc,
+  encodeStateAsUpdate,
+  encodeStateVector,
+  UndoManager,
+} from 'yjs';
+
+type InputFormat = 'file' | 'base64' | 'hex';
+type OutputFormat = 'bin' | 'base64' | 'hex';
+
+const HELP_TEXT = `
+Generate a revert update from two Yjs snapshot binaries.
+
+Usage:
+  r ./tools/revert-update/index.ts --from <value> --to <value> [options]
+
+Options:
+  --from <value>         Newer snapshot input (path/base64/hex)
+  --to <value>           Older snapshot input (path/base64/hex)
+  --from-format <fmt>    file|base64|hex (default: file)
+  --to-format <fmt>      file|base64|hex (default: file)
+  --out <path>           Output path (default: stdout)
+  --out-format <fmt>     bin|base64|hex (default: base64 if stdout, bin if file)
+  -h, --help             Show help
+
+Examples:
+  r ./tools/revert-update/index.ts --from ./from.bin --to ./to.bin --out ./revert.bin
+  r ./tools/revert-update/index.ts --from "$FROM" --from-format base64 --to "$TO" --to-format base64
+`;
+
+function generateRevertUpdate(
+  fromNewerBin: Uint8Array,
+  toOlderBin: Uint8Array
+): Uint8Array {
+  const newerDoc = new Doc();
+  applyUpdate(newerDoc, fromNewerBin);
+  const olderDoc = new Doc();
+  applyUpdate(olderDoc, toOlderBin);
+
+  const newerState = encodeStateVector(newerDoc);
+  const olderState = encodeStateVector(olderDoc);
+
+  const diff = encodeStateAsUpdate(newerDoc, olderState);
+  const undoManager = new UndoManager(Array.from(olderDoc.share.values()));
+
+  applyUpdate(olderDoc, diff);
+  undoManager.undo();
+
+  return encodeStateAsUpdate(olderDoc, newerState);
+}
+
+function fail(message: string): never {
+  console.error(message);
+  console.error(HELP_TEXT.trim());
+  process.exit(1);
+}
+
+function parseInputFormat(value: string, flag: string): InputFormat {
+  switch (value) {
+    case 'file':
+    case 'base64':
+    case 'hex':
+      return value;
+    default:
+      fail(`Unknown ${flag} value: ${value}`);
+  }
+}
+
+function parseOutputFormat(value: string, flag: string): OutputFormat {
+  switch (value) {
+    case 'bin':
+    case 'base64':
+    case 'hex':
+      return value;
+    default:
+      fail(`Unknown ${flag} value: ${value}`);
+  }
+}
+
+function parseArgs(argv: string[]) {
+  const args = new Map<string, string>();
+  for (let i = 0; i < argv.length; i += 1) {
+    const arg = argv[i];
+    if (arg === '--help' || arg === '-h') {
+      console.log(HELP_TEXT.trim());
+      process.exit(0);
+    }
+    if (!arg.startsWith('--')) {
+      fail(`Unknown argument: ${arg}`);
+    }
+    const value = argv[i + 1];
+    if (!value || value.startsWith('--')) {
+      fail(`Missing value for ${arg}`);
+    }
+    args.set(arg, value);
+    i += 1;
+  }
+
+  const from = args.get('--from');
+  const to = args.get('--to');
+  if (!from || !to) {
+    fail('Both --from and --to are required.');
+  }
+
+  const fromFormat = parseInputFormat(
+    (args.get('--from-format') ?? 'file').toLowerCase(),
+    '--from-format'
+  );
+  const toFormat = parseInputFormat(
+    (args.get('--to-format') ?? 'file').toLowerCase(),
+    '--to-format'
+  );
+
+  const outPath = args.get('--out');
+  const defaultOutFormat = outPath ? 'bin' : 'base64';
+  const outFormat = parseOutputFormat(
+    (args.get('--out-format') ?? defaultOutFormat).toLowerCase(),
+    '--out-format'
+  );
+
+  return {
+    from,
+    to,
+    fromFormat,
+    toFormat,
+    outPath,
+    outFormat,
+  };
+}
+
+function readInput(value: string, format: InputFormat): Uint8Array {
+  try {
+    if (format === 'file') {
+      return new Uint8Array(readFileSync(value));
+    }
+    const trimmed = value.trim();
+    const decoded = Buffer.from(trimmed, format === 'hex' ? 'hex' : 'base64');
+    return new Uint8Array(decoded);
+  } catch (error) {
+    const details = error instanceof Error ? error.message : String(error);
+    fail(`Failed to read ${format} input: ${details}`);
+  }
+}
+
+function writeOutput(
+  update: Uint8Array,
+  outPath: string | undefined,
+  format: OutputFormat
+) {
+  if (outPath) {
+    if (format === 'bin') {
+      writeFileSync(outPath, update);
+      return;
+    }
+    const encoded = Buffer.from(update).toString(format);
+    writeFileSync(outPath, encoded);
+    return;
+  }
+
+  if (format === 'bin') {
+    process.stdout.write(Buffer.from(update));
+    return;
+  }
+  const encoded = Buffer.from(update).toString(format);
+  process.stdout.write(`${encoded}\n`);
+}
+
+const { from, to, fromFormat, toFormat, outPath, outFormat } = parseArgs(
+  process.argv.slice(2)
+);
+
+const fromBin = readInput(from, fromFormat);
+const toBin = readInput(to, toFormat);
+
+const revertUpdate = generateRevertUpdate(fromBin, toBin);
+
+writeOutput(revertUpdate, outPath, outFormat);
diff --git a/tools/revert-update/package.json b/tools/revert-update/package.json
new file mode 100644
index 0000000000..c00a9cc8bd
--- /dev/null
+++ b/tools/revert-update/package.json
@@ -0,0 +1,19 @@
+{
+  "name": "@affine/revert-update",
+  "version": "0.26.0",
+  "private": true,
+  "type": "module",
+  "description": "Generate a revert update from two Yjs snapshot binaries",
+  "main": "index.ts",
+  "scripts": {
+    "generate": "r ./index.ts"
+  },
+  "dependencies": {
+    "@affine-tools/cli": "workspace:*",
+    "typescript": "^5.7.2",
+    "yjs": "^13.6.27"
+  },
+  "devDependencies": {
+    "@types/node": "^22.0.0"
+  }
+}
diff --git a/tools/revert-update/tsconfig.json b/tools/revert-update/tsconfig.json
new file mode 100644
index 0000000000..98b83b35cc
--- /dev/null
+++ b/tools/revert-update/tsconfig.json
@@ -0,0 +1,8 @@
+{
+  "extends": "../../tsconfig.node.json",
+  "compilerOptions": {
+    "outDir": "dist"
+  },
+  "files": ["index.ts"],
+  "references": [{ "path": "../cli" }]
+}
diff --git a/tools/utils/src/workspace.gen.ts b/tools/utils/src/workspace.gen.ts
index 3b5c6eb94d..f7f560bd90 100644
--- a/tools/utils/src/workspace.gen.ts
+++ b/tools/utils/src/workspace.gen.ts
@@ -1476,6 +1476,11 @@ export const PackageList = [
     name: '@affine/playstore-auto-bump',
     workspaceDependencies: ['tools/cli', 'tools/utils'],
   },
+  {
+    location: 'tools/revert-update',
+    name: '@affine/revert-update',
+    workspaceDependencies: ['tools/cli'],
+  },
   {
     location: 'tools/utils',
     name: '@affine-tools/utils',
@@ -1598,4 +1603,5 @@ export type PackageName =
   | '@affine/commitlint-config'
   | '@affine/copilot-result'
   | '@affine/playstore-auto-bump'
+  | '@affine/revert-update'
   | '@affine-tools/utils';
diff --git a/tsconfig.json b/tsconfig.json
index 1a43f6aa29..ec6635d2f8 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -157,6 +157,7 @@
     { "path": "./tests/kit" },
     { "path": "./tools/cli" },
     { "path": "./tools/playstore-auto-bump" },
+    { "path": "./tools/revert-update" },
     { "path": "./tools/utils" }
   ]
 }