diff --git a/apps/web/src/frontend/features/sql-editor/components/DataMigrateBar.tsx b/apps/web/src/frontend/features/sql-editor/components/DataMigrateBar.tsx
index 6bc3744b2..f98624859 100644
--- a/apps/web/src/frontend/features/sql-editor/components/DataMigrateBar.tsx
+++ b/apps/web/src/frontend/features/sql-editor/components/DataMigrateBar.tsx
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  *
  * Side-by-side data migrate: key-based insert/update/delete onto a destination
- * grid (≤500 ops). Larger sets toast with Server Beam instructions.
+ * grid (≤ DATA_MIGRATE_ROW_CAP ops, 2,000). Larger sets toast with Server Beam instructions.
  */
 import React, { useEffect, useMemo, useState } from 'react';
 import { createPortal } from 'react-dom';
diff --git a/apps/web/src/frontend/features/sql-editor/components/ResultsPanel.tsx b/apps/web/src/frontend/features/sql-editor/components/ResultsPanel.tsx
index b5bec7b7e..611c7d7b3 100644
--- a/apps/web/src/frontend/features/sql-editor/components/ResultsPanel.tsx
+++ b/apps/web/src/frontend/features/sql-editor/components/ResultsPanel.tsx
@@ -57,7 +57,7 @@ import {
   compareKeyAlignedGrids,
   type AlignRowOp,
 } from '@/features/sql-editor/lib/resultKeyAlign';
-import { migrateGridsAreComplete } from '@/features/sql-editor/lib/resultRowDiff';
+import { DATA_MIGRATE_ROW_CAP, migrateGridsAreComplete } from '@/features/sql-editor/lib/resultRowDiff';
 import {
   COMPARE_PAGE_SIZES,
   COMPARE_WINDOW_ROWS,
@@ -1754,7 +1754,7 @@ const SideBySideStatementSection: React.FC<{
       <span className="text-sky-400/90">Sync</span> column (on by default for differing rows).{' '}
       <span className="text-sky-400/90">Sync scroll</span> keeps all grids aligned;{' '}
       <span className="text-sky-400/90">CSV all</span> downloads every grid in one file. Migrate
-      needs Add / Edit / Delete checked (enabled when diffs exist) plus Sync rows. Cap: 500 ops —
+      needs Add / Edit / Delete checked (enabled when diffs exist) plus Sync rows. Cap: {DATA_MIGRATE_ROW_CAP.toLocaleString()} ops —
       larger sets use Server Beam.
     </p>
   ) : null;
diff --git a/apps/web/src/frontend/features/sql-editor/lib/resultRowDiff.test.ts b/apps/web/src/frontend/features/sql-editor/lib/resultRowDiff.test.ts
index dc6a0c83a..96560f904 100644
--- a/apps/web/src/frontend/features/sql-editor/lib/resultRowDiff.test.ts
+++ b/apps/web/src/frontend/features/sql-editor/lib/resultRowDiff.test.ts
@@ -207,15 +207,15 @@ describe('migrateKeysSafeForMutatingOps', () => {
 });
 
 describe('selectMigrateOps', () => {
-  it('respects checkboxes and caps at 500', () => {
-    const inserts = Array.from({ length: 300 }, (_, i) => ({
+  it('respects checkboxes and caps at the shared limit (2,000)', () => {
+    const inserts = Array.from({ length: 1200 }, (_, i) => ({
       op: 'insert' as const,
       keyLabel: `id=${i}`,
       sourceRow: [i],
     }));
-    const updates = Array.from({ length: 300 }, (_, i) => ({
+    const updates = Array.from({ length: 900 }, (_, i) => ({
       op: 'update' as const,
-      keyLabel: `id=${i + 1000}`,
+      keyLabel: `id=${i + 5000}`,
       sourceRow: [i],
       destRow: [i],
     }));
@@ -225,7 +225,7 @@ describe('selectMigrateOps', () => {
       deletes: [],
       skippedNullKeys: 0,
       duplicateKeys: 0,
-      totalOps: 600,
+      totalOps: 2100,
       unresolved: 0,
     };
     const selected = selectMigrateOps(
@@ -233,7 +233,8 @@ describe('selectMigrateOps', () => {
       { insert: true, update: true, delete: false },
       DATA_MIGRATE_ROW_CAP
     );
-    expect(selected.uncappedCount).toBe(600);
+    expect(DATA_MIGRATE_ROW_CAP).toBe(2000);
+    expect(selected.uncappedCount).toBe(2100);
     expect(selected.truncated).toBe(true);
     expect(selected.ops).toHaveLength(DATA_MIGRATE_ROW_CAP);
     expect(selected.ops.every((o) => o.op === 'insert' || o.op === 'update')).toBe(
diff --git a/apps/web/src/frontend/features/sql-editor/lib/resultRowDiff.ts b/apps/web/src/frontend/features/sql-editor/lib/resultRowDiff.ts
index b3d3d9b25..cc863f686 100644
--- a/apps/web/src/frontend/features/sql-editor/lib/resultRowDiff.ts
+++ b/apps/web/src/frontend/features/sql-editor/lib/resultRowDiff.ts
@@ -9,9 +9,11 @@
 
 import { resultValuesEqual, type ResultGridLike } from './resultDataDiff';
 import { normalizeResultKey } from '@/features/sql-editor/lib/resultValueKey';
+import { DATA_MIGRATE_MAX_OPS } from '@foxschema/shared';
 import type { PeekKeyColumn } from './rowDml';
 
-export const DATA_MIGRATE_ROW_CAP = 500;
+/** The route refuses more than this (`DATA_MIGRATE_MAX_OPS`, shared with the server). */
+export const DATA_MIGRATE_ROW_CAP = DATA_MIGRATE_MAX_OPS;
 
 export type RowDiffOp = 'insert' | 'update' | 'delete';
 
diff --git a/packages/server/src/features/data-migrate/data-migrate.routes.test.ts b/packages/server/src/features/data-migrate/data-migrate.routes.test.ts
index 62a1d5916..d9e58b35c 100644
--- a/packages/server/src/features/data-migrate/data-migrate.routes.test.ts
+++ b/packages/server/src/features/data-migrate/data-migrate.routes.test.ts
@@ -11,6 +11,7 @@ import { beforeEach, describe, expect, it, vi } from 'vitest';
 import { fakeReply, routeHandler } from '../../platform/http/route-doubles';
 import { createDataMigrateRoutes } from './data-migrate.routes';
 import { executeDataMigrateOps } from './data-migrate-execute';
+import { DATA_MIGRATE_MAX_OPS } from '@foxschema/shared';
 
 vi.mock('./data-migrate-execute', () => ({ executeDataMigrateOps: vi.fn(async () => ({ results: [] })) }));
 
@@ -37,6 +38,31 @@ describe('POST /data-migrate/execute', () => {
     expect(executeDataMigrateOps).not.toHaveBeenCalled();
   });
 
+  it('takes up to DATA_MIGRATE_MAX_OPS (2,000) ops, and refuses one more', async () => {
+    const handler = routeHandler(
+      createDataMigrateRoutes({
+        resolveRef: vi.fn().mockResolvedValue({ dialect: 'sqlite', option: {}, schema: '' }),
+        dataMigrateHistory: {} as never,
+      }),
+      'POST',
+      '/data-migrate/execute'
+    );
+    const ops = (n: number) =>
+      Array.from({ length: n }, (_, i) => ({ op: 'insert', key: `id=${i}`, sql: `INSERT INTO t (id) VALUES (${i})` }));
+    const call = async (n: number) => {
+      const { reply, sent } = fakeReply();
+      await handler({ body: { connectionId: 'c1', ops: ops(n) }, userId: 'u1', appRole: 'admin' } as never, reply as never);
+      return sent;
+    };
+    expect(DATA_MIGRATE_MAX_OPS).toBe(2000);
+    const over = await call(2001);
+    expect(over.status).toBe(400);
+    expect(over.body.error).toMatch(/At most 2000 ops/);
+    expect(executeDataMigrateOps).not.toHaveBeenCalled();
+    await call(2000);
+    expect(executeDataMigrateOps).toHaveBeenCalledOnce();
+  });
+
   it('counts the statements inside a code fence', async () => {
     const handler = routeHandler(
       createDataMigrateRoutes({
diff --git a/packages/server/src/features/data-migrate/data-migrate.routes.ts b/packages/server/src/features/data-migrate/data-migrate.routes.ts
index 2243d0d64..c57df73f8 100644
--- a/packages/server/src/features/data-migrate/data-migrate.routes.ts
+++ b/packages/server/src/features/data-migrate/data-migrate.routes.ts
@@ -14,6 +14,7 @@ import { requirePermissions, denyUnless } from '../../platform/authorization/rba
 import type { AuthedRequest } from '../../platform/http/types';
 import type { ConnectionRef } from '../../platform/connections/resolve';
 import { rateLimit } from '../../platform/guards/rate-limit';
+import { DATA_MIGRATE_MAX_OPS } from '@foxschema/shared';
 import { MAX_STATEMENT_LENGTH } from '../sql-editor';
 import type { Permission } from '@foxschema/shared';
 import { CATEGORY_PERMISSION, DATAGRID_ACTION_PERMISSION } from '@foxschema/shared';
@@ -52,8 +53,8 @@ export function createDataMigrateRoutes(deps: DataMigrateRouteDeps): Router {
         sendError(res, 'invalid_input', 'ops[] is required.');
         return;
       }
-      if (body.ops.length > 500) {
-        sendError(res, 'invalid_input', 'At most 500 ops per data migrate.');
+      if (body.ops.length > DATA_MIGRATE_MAX_OPS) {
+        sendError(res, 'invalid_input', `At most ${DATA_MIGRATE_MAX_OPS} ops per data migrate.`);
         return;
       }
       // The connection first: each op is classified as its database reads it.
diff --git a/packages/shared/src/data-migrate.ts b/packages/shared/src/data-migrate.ts
new file mode 100644
index 000000000..66a6901f7
--- /dev/null
+++ b/packages/shared/src/data-migrate.ts
@@ -0,0 +1,14 @@
+/**
+ * Fox Schema (foxschema)
+ * Copyright 2024-2026 Huy Phan <huyplb@gmail.com>
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The most row operations one Data migrate sends. The browser caps what it
+ * offers and the route refuses more, from this one number: the two used to
+ * hold their own copies (500 each), and a change to one would have left the
+ * screen offering what the server refused.
+ *
+ * It matches the compare window (2,000 rows per side), so every difference a
+ * compare run finds can be applied from the screen that found it.
+ */
+export const DATA_MIGRATE_MAX_OPS = 2000;
diff --git a/packages/shared/src/index.ts b/packages/shared/src/index.ts
index 2fd4c042e..361deb561 100644
--- a/packages/shared/src/index.ts
+++ b/packages/shared/src/index.ts
@@ -18,3 +18,4 @@ export * from './lokee-wire';
 export * from './nav';
 export * from './password-policy';
 export * from './migration-status';
+export * from './data-migrate';