fix(next-plugin): fall back when lite WASM is unavailable

.changepacks/changepack_fixWasmLiteResolution20260830.json

@@ -0,0 +1,7 @@
+{
+  "changes": {
+    "packages/next-plugin/package.json": "Patch"
+  },
+  "note": "Fall back to the full WASM engine when an installed @devup-ui/wasm package does not expose the lite entry point",
+  "date": "2026-08-30T00:00:00.000Z"
+}

packages/next-plugin/src/__tests__/wasm.test.ts

@@ -5,6 +5,7 @@ import { afterEach, describe, expect, it } from 'bun:test'
 import {
   loadWasm,
   loadWebpackPlugin,
+  requireWasm,
   setWasmForTesting,
   setWebpackPluginForTesting,
 } from '../wasm'
@@ -26,6 +27,39 @@ describe('WASM selection', () => {
     expect(typeof loadWasm(true).codeExtract).toBe('function')
   })
 
+  it.each(['MODULE_NOT_FOUND', 'ERR_PACKAGE_PATH_NOT_EXPORTED'])(
+    'falls back to the full package when the lite export fails with %s',
+    (code) => {
+      const specifiers: string[] = []
+      const loaded = requireWasm(true, (specifier) => {
+        specifiers.push(specifier)
+        if (specifier.endsWith('/lite')) {
+          const message =
+            code === 'ERR_PACKAGE_PATH_NOT_EXPORTED'
+              ? "Package subpath './lite' is not defined by exports in node_modules/@devup-ui/wasm/package.json"
+              : "Cannot find module '@devup-ui/wasm/lite'"
+          throw Object.assign(new Error(message), { code })
+        }
+        return wasm
+      })
+
+      expect(loaded).toBe(wasm)
+      expect(specifiers).toEqual(['@devup-ui/wasm/lite', '@devup-ui/wasm'])
+    },
+  )
+
+  it('does not hide failures while loading an available lite export', () => {
+    const loadError = Object.assign(new Error('invalid WASM binary'), {
+      code: 'MODULE_NOT_FOUND',
+    })
+
+    expect(() =>
+      requireWasm(true, () => {
+        throw loadError
+      }),
+    ).toThrow(loadError)
+  })
+
   it('loads or injects the Webpack plugin without a static dependency', () => {
     expect(typeof loadWebpackPlugin().DevupUIWebpackPlugin).toBe('function')
     setWebpackPluginForTesting(webpackPlugin)

packages/next-plugin/src/wasm.ts

@@ -28,13 +28,45 @@ function requireFromPlugin<T>(specifier: string): T {
   return createRequire(requireBase)(specifier) as T
 }
 
+type WasmLoader = (specifier: string) => DevupWasm
+
+function isMissingLiteWasm(error: unknown): boolean {
+  if (!(error instanceof Error) || !('code' in error)) return false
+  if (error.code === 'ERR_PACKAGE_PATH_NOT_EXPORTED') {
+    return (
+      error.message.includes("Package subpath './lite'") &&
+      error.message.includes('@devup-ui') &&
+      error.message.includes('wasm')
+    )
+  }
+  return (
+    error.code === 'MODULE_NOT_FOUND' &&
+    error.message.includes('@devup-ui/wasm/lite')
+  )
+}
+
+/** @internal Resolve the lite engine, falling back for older WASM packages. */
+export function requireWasm(
+  lite: boolean,
+  requireModule: WasmLoader = (specifier) =>
+    requireFromPlugin<DevupWasm>(specifier),
+): DevupWasm {
+  if (!lite) return requireModule('@devup-ui/wasm')
+  try {
+    return requireModule('@devup-ui/wasm/lite')
+  } catch (error) {
+    if (!isMissingLiteWasm(error)) throw error
+    return requireModule('@devup-ui/wasm')
+  }
+}
+
 /** Load exactly one extraction engine for the lifetime of a Next config. */
 export function loadWasm(lite: boolean): DevupWasm {
   if (wasmForTesting) return wasmForTesting
   if (lite) {
-    return (liteWasm ??= requireFromPlugin<DevupWasm>('@devup-ui/wasm/lite'))
+    return (liteWasm ??= requireWasm(true))
   }
-  return (fullWasm ??= requireFromPlugin<DevupWasm>('@devup-ui/wasm'))
+  return (fullWasm ??= requireWasm(false))
 }
 
 /** Keep the Webpack adapter (and its full WASM) out of Turbopack startup. */