diff --git a/reconcile-js/src/index.rn.test.ts b/reconcile-js/src/index.rn.test.ts
deleted file mode 100644
index 682c494..0000000
--- a/reconcile-js/src/index.rn.test.ts
+++ /dev/null
@@ -1,135 +0,0 @@
-import { reconcile, reconcileWithHistory, diff, undiff } from './index.rn';
-import { installWasmLeakDetector, checkForWasmLeaks } from './wasm-leak-detector';
-import * as fs from 'fs';
-import * as path from 'path';
-import { fileURLToPath } from 'url';
-
-const __dirname = path.dirname(fileURLToPath(import.meta.url));
-
-installWasmLeakDetector();
-
-afterEach(() => {
-  const leaks = checkForWasmLeaks();
-  if (leaks.length > 0) {
-    throw new Error(
-      `WASM memory leak: ${leaks.length} object(s) not freed:\n  ${leaks.join('\n  ')}`
-    );
-  }
-});
-
-describe('reconcile (wasm2js / React Native build)', () => {
-  it('call reconcile without cursors', () => {
-    expect(reconcile('Hello', 'Hello world', 'Hi world').text).toEqual('Hi world');
-  });
-
-  it('call reconcile with cursors', () => {
-    const result = reconcile(
-      'Hello',
-      {
-        text: 'Hello world',
-        cursors: [
-          {
-            id: 3,
-            position: 2,
-          },
-        ],
-      },
-      {
-        text: 'Hi world',
-        cursors: [
-          {
-            id: 4,
-            position: 0,
-          },
-          { id: 5, position: 3 },
-        ],
-      }
-    );
-
-    expect(result.text).toEqual('Hi world');
-    expect(result.cursors).toEqual([
-      { id: 3, position: 0 },
-      { id: 4, position: 0 },
-      { id: 5, position: 3 },
-    ]);
-  });
-
-  it('call reconcileWithHistory', () => {
-    const result = reconcileWithHistory('Hello', 'Hello world', 'Hi world');
-
-    expect(result.text).toEqual('Hi world');
-    expect(result.history.length).toBeGreaterThan(0);
-  });
-
-  it('undiff accepts bigint entries (per the Array<number | bigint | string> type)', () => {
-    const original = 'Hello world';
-    const changed = 'Hello cruel world';
-
-    // `diff` returns plain numbers; emulate a caller that supplies BigInt, which
-    // the public signature permits. The wasm2js (React Native) build rejects raw
-    // BigInt, so the wrapper must normalise it to keep both backends identical.
-    const withBigints = diff(original, changed).map((item) =>
-      typeof item === 'number' ? BigInt(item) : item
-    );
-
-    expect(withBigints.some((item) => typeof item === 'bigint')).toBe(true);
-    expect(undiff(original, withBigints)).toEqual(changed);
-  });
-
-  it('runs every operation with no WebAssembly global (Hermes parity)', () => {
-    // Hermes exposes no `WebAssembly` global - the entire reason the React
-    // Native entry point links a wasm2js (pure-JS) build instead of the real
-    // module. Remove the global to prove the operations never reach for it.
-    const descriptor = Object.getOwnPropertyDescriptor(globalThis, 'WebAssembly');
-    delete (globalThis as { WebAssembly?: unknown }).WebAssembly;
-    try {
-      expect((globalThis as { WebAssembly?: unknown }).WebAssembly).toBeUndefined();
-
-      expect(reconcile('Hello', 'Hello world', 'Hi world').text).toEqual('Hi world');
-
-      const changes = diff('Hello world', 'Hello cruel world');
-      expect(undiff('Hello world', changes)).toEqual('Hello cruel world');
-
-      expect(
-        reconcileWithHistory('Hello', 'Hello world', 'Hi world').history.length
-      ).toBeGreaterThan(0);
-    } finally {
-      // Restore the global so the leak check and later suites are unaffected.
-      if (descriptor) {
-        Object.defineProperty(globalThis, 'WebAssembly', descriptor);
-      }
-    }
-  });
-});
-
-describe('test_diff_and_undiff_are_inverse (wasm2js / React Native build)', () => {
-  const resourcesPath = path.join(__dirname, '../../tests/resources');
-
-  const readFileSlice = (fileName: string, start: number, end: number): string => {
-    const filePath = path.join(resourcesPath, fileName);
-    const content = fs.readFileSync(filePath, 'utf-8');
-    const chars = Array.from(content); // Handle unicode properly
-    return chars.slice(start, Math.min(end, chars.length)).join('');
-  };
-
-  const files = ['pride_and_prejudice.txt', 'room_with_a_view.txt', 'blns.txt'];
-
-  const ranges = [{ start: 0, end: 50000 }];
-
-  files.forEach((file1) => {
-    files.forEach((file2) => {
-      ranges.forEach((range1) => {
-        ranges.forEach((range2) => {
-          it(`should diff & undiff ${file1}[${range1.start}..${range1.end}], ${file2}[${range2.start}..${range2.end}] without panic`, () => {
-            const content1 = readFileSlice(file1, range1.start, range1.end);
-            const content2 = readFileSlice(file2, range2.start, range2.end);
-
-            const changes = diff(content1, content2);
-            const actual = undiff(content1, changes);
-            expect(actual).toEqual(content2);
-          });
-        });
-      });
-    });
-  });
-});
diff --git a/reconcile-js/src/index.test.ts b/reconcile-js/src/index.test.ts
index 0fbea9a..66d385b 100644
--- a/reconcile-js/src/index.test.ts
+++ b/reconcile-js/src/index.test.ts
@@ -1,4 +1,5 @@
-import { reconcile, reconcileWithHistory, diff, undiff } from './index';
+import * as webApi from './index';
+import * as rnApi from './index.rn';
 import { installWasmLeakDetector, checkForWasmLeaks } from './wasm-leak-detector';
 import * as fs from 'fs';
 import * as path from 'path';
@@ -17,7 +18,18 @@ afterEach(() => {
   }
 });
 
-describe('reconcile', () => {
+// `./index` is the web/node build (real WebAssembly); `./index.rn` is the React
+// Native build (the wasm2js pure-JS translation). Both are thin backends over the
+// same `src/core.ts` wrapper and expose an identical public API, so the behavioural
+// suite below runs against both to guarantee they stay in lock-step.
+const backends = [
+  { name: 'web/node (WebAssembly)', api: webApi },
+  { name: 'React Native (wasm2js)', api: rnApi },
+];
+
+describe.each(backends)('reconcile [$name]', ({ api }) => {
+  const { reconcile, reconcileWithHistory, diff, undiff } = api;
+
   it('call reconcile without cursors', () => {
     expect(reconcile('Hello', 'Hello world', 'Hi world').text).toEqual('Hi world');
   });
@@ -65,9 +77,9 @@ describe('reconcile', () => {
     const original = 'Hello world';
     const changed = 'Hello cruel world';
 
-    // `diff` returns plain numbers; emulate a caller that supplies BigInt, which
-    // the public signature permits. The wasm2js (React Native) build rejects raw
-    // BigInt, so the wrapper must normalise it to keep both backends identical.
+    // `diff` returns plain numbers; emulate a caller that supplies BigInt, which the
+    // public signature permits. The wasm2js build rejects raw BigInt, so the shared
+    // wrapper must normalise it — running this on both backends asserts the contract.
     const withBigints = diff(original, changed).map((item) =>
       typeof item === 'number' ? BigInt(item) : item
     );
@@ -77,7 +89,9 @@ describe('reconcile', () => {
   });
 });
 
-describe('test_diff_and_undiff_are_inverse', () => {
+describe.each(backends)('diff and undiff are inverse [$name]', ({ api }) => {
+  const { diff, undiff } = api;
+
   const resourcesPath = path.join(__dirname, '../../tests/resources');
 
   const readFileSlice = (fileName: string, start: number, end: number): string => {
@@ -108,3 +122,31 @@ describe('test_diff_and_undiff_are_inverse', () => {
     });
   });
 });
+
+// React-Native-only: Hermes exposes no `WebAssembly` global, which is the whole reason
+// the RN entry point links a wasm2js build. Only the wasm2js backend can satisfy this.
+describe('React Native (wasm2js) Hermes parity', () => {
+  const { reconcile, reconcileWithHistory, diff, undiff } = rnApi;
+
+  it('runs every operation with no WebAssembly global', () => {
+    const descriptor = Object.getOwnPropertyDescriptor(globalThis, 'WebAssembly');
+    delete (globalThis as { WebAssembly?: unknown }).WebAssembly;
+    try {
+      expect((globalThis as { WebAssembly?: unknown }).WebAssembly).toBeUndefined();
+
+      expect(reconcile('Hello', 'Hello world', 'Hi world').text).toEqual('Hi world');
+
+      const changes = diff('Hello world', 'Hello cruel world');
+      expect(undiff('Hello world', changes)).toEqual('Hello cruel world');
+
+      expect(
+        reconcileWithHistory('Hello', 'Hello world', 'Hi world').history.length
+      ).toBeGreaterThan(0);
+    } finally {
+      // Restore the global so the leak check and later suites are unaffected.
+      if (descriptor) {
+        Object.defineProperty(globalThis, 'WebAssembly', descriptor);
+      }
+    }
+  });
+});