Add Next.js cache invalidation on swc transform change

.changeset/shy-mice-reply.md

@@ -0,0 +1,5 @@
+---
+"@workflow/next": patch
+---
+
+Add Next.js cache invalidation on swc transform change

.gitignore

@@ -21,6 +21,8 @@ node_modules
 target
 # compiled wasm
 *.wasm
+# swc-plugin build hash
+packages/swc-plugin-workflow/build-hash.json
 
 # SWC plugin cache
 .swc

packages/next/src/index.ts

@@ -1,6 +1,8 @@
 import type { NextConfig } from 'next';
+import path from 'path';
 import semver from 'semver';
 import { getNextBuilder } from './builder.js';
+import { maybeInvalidateCacheOnSwcChange } from './swc-cache.js';
 
 /**
  * Default directories to scan for workflows and steps.
@@ -136,6 +138,13 @@ export function withWorkflow(
       !process.env.WORKFLOW_NEXT_PRIVATE_BUILT &&
       phase !== 'phase-production-server'
     ) {
+      // Check swc-plugin build hash and invalidate cache if changed
+      const distDir = path.resolve(
+        process.cwd(),
+        nextConfig.distDir || '.next'
+      );
+      maybeInvalidateCacheOnSwcChange(distDir);
+
       const shouldWatch = process.env.NODE_ENV === 'development';
       const NextBuilder = await getNextBuilder();
       const workflowBuilder = new NextBuilder({

packages/next/src/swc-cache.ts

@@ -0,0 +1,51 @@
+import fs from 'fs';
+import path from 'path';
+
+/**
+ * Checks if the SWC plugin build has changed and invalidates the Next.js cache if needed.
+ * Also registers an exit handler to write the current build hash for future comparisons.
+ *
+ * @param distDir - The Next.js dist directory (e.g., '.next')
+ */
+export function maybeInvalidateCacheOnSwcChange(distDir: string): void {
+  const cacheDir = path.join(distDir, 'cache');
+  const devCacheDir = path.join(distDir, 'dev', 'cache');
+  const workflowJsonPath = path.join(cacheDir, 'workflow.json');
+  const swcPluginBuildHash = require('@workflow/swc-plugin/build-hash.json')
+    .buildHash as string;
+
+  let shouldInvalidateCache = false;
+  try {
+    const existing = JSON.parse(fs.readFileSync(workflowJsonPath, 'utf-8'));
+    if (existing.swcPluginBuildHash !== swcPluginBuildHash) {
+      shouldInvalidateCache = true;
+    }
+  } catch {
+    // File doesn't exist or is invalid
+    shouldInvalidateCache = true;
+  }
+
+  if (shouldInvalidateCache) {
+    console.log('workflow transform upgraded, invalidating Next.js cache');
+    // Delete cache directories
+    const cacheDirs = [cacheDir, devCacheDir];
+    for (const dir of cacheDirs) {
+      if (fs.existsSync(dir)) {
+        fs.rmSync(dir, { recursive: true, force: true });
+      }
+    }
+  }
+
+  // Write workflow.json lazily on process exit
+  process.on('exit', () => {
+    try {
+      fs.mkdirSync(cacheDir, { recursive: true });
+      fs.writeFileSync(
+        workflowJsonPath,
+        JSON.stringify({ swcPluginBuildHash }, null, 2)
+      );
+    } catch {
+      // Ignore errors on exit
+    }
+  });
+}

packages/swc-plugin-workflow/build.js

@@ -1,5 +1,12 @@
+import { createHash } from 'node:crypto';
 import { execSync } from 'node:child_process';
-import { copyFileSync, existsSync, readdirSync } from 'node:fs';
+import {
+  copyFileSync,
+  existsSync,
+  readdirSync,
+  readFileSync,
+  writeFileSync,
+} from 'node:fs';
 
 function runCommand(command) {
   try {
@@ -116,4 +123,15 @@ if (!existsSync(wasmSource)) {
 console.log('Copying WASM file...');
 copyFileSync(wasmSource, wasmDest);
 
+// Generate hash of the WASM file for cache invalidation
+console.log('Generating build hash...');
+const wasmContent = readFileSync(wasmDest);
+const buildHash = createHash('sha256')
+  .update(wasmContent)
+  .digest('hex')
+  .slice(0, 16);
+const buildHashPath = new URL('build-hash.json', import.meta.url);
+writeFileSync(buildHashPath, JSON.stringify({ buildHash }, null, 2));
+console.log(`Build hash: ${buildHash}`);
+
 console.log('Build complete!');

packages/swc-plugin-workflow/package.json

@@ -6,7 +6,8 @@
   "type": "module",
   "main": "swc_plugin_workflow.wasm",
   "files": [
-    "swc_plugin_workflow.wasm"
+    "swc_plugin_workflow.wasm",
+    "build-hash.json"
   ],
   "publishConfig": {
     "access": "public"
@@ -17,7 +18,9 @@
     "directory": "packages/swc-plugin-workflow"
   },
   "exports": {
-    ".": "./swc_plugin_workflow.wasm"
+    ".": "./swc_plugin_workflow.wasm",
+    "./package.json": "./package.json",
+    "./build-hash.json": "./build-hash.json"
   },
   "peerDependencies": {
     "@swc/core": "catalog:"

packages/swc-plugin-workflow/turbo.json

@@ -3,7 +3,7 @@
   "extends": ["//"],
   "tasks": {
     "build": {
-      "outputs": ["swc_plugin_workflow.wasm"],
+      "outputs": ["swc_plugin_workflow.wasm", "build-hash.json"],
       "env": ["RUSTUP_HOME", "CARGO_HOME"]
     }
   }