chore: Fix hot reload for nodes-langchain package (no-changelog) (#17111)

packages/@n8n/nodes-langchain/package.json

@@ -14,7 +14,7 @@
     "format:check": "biome ci .",
     "lint": "eslint nodes credentials utils --quiet",
     "lintfix": "eslint nodes credentials utils --fix",
-    "watch": "tsup --watch --tsconfig tsconfig.build.json --onSuccess \"pnpm copy-nodes-json && tsc-alias -p tsconfig.build.json && pnpm n8n-generate-metadata\"",
+    "watch": "tsup --watch nodes --watch credentials --watch utils --watch types --tsconfig tsconfig.build.json --onSuccess \"node ./scripts/post-build.js\"",
     "test": "jest",
     "test:dev": "jest --watch"
   },

packages/@n8n/nodes-langchain/scripts/post-build.js

@@ -0,0 +1,23 @@
+/**
+ * Post-build script
+ *
+ * This is a separate script instead of inline npm commands because using "&&"" to chain commands in --onSuccess can cause the watch mode to hang
+ */
+
+const { execSync } = require('child_process');
+
+function runCommand(command) {
+	try {
+		execSync(command, { stdio: 'inherit' });
+	} catch (error) {
+		console.error(`Command failed: ${command}`);
+		process.exit(1);
+	}
+}
+
+// Run all post-build tasks
+runCommand('npx tsc-alias -p tsconfig.build.json');
+runCommand('node scripts/copy-tokenizer-json.js .');
+runCommand('node ../../nodes-base/scripts/copy-nodes-json.js .');
+runCommand('pnpm n8n-copy-static-files');
+runCommand('pnpm n8n-generate-metadata');

packages/cli/package.json

@@ -10,7 +10,7 @@
     "build": "tsc -p tsconfig.build.json && tsc-alias -p tsconfig.build.json && pnpm run build:data",
     "build:data": "node scripts/build.mjs",
     "buildAndDev": "pnpm run build && pnpm run dev",
-    "dev": "concurrently -k -n \"TypeScript,Node\" -c \"yellow.bold,cyan.bold\" \"npm run watch\" \"nodemon\"",
+    "dev": "concurrently -k -n \"TypeScript,Node\" -c \"yellow.bold,cyan.bold\" \"npm run watch\" \"nodemon --delay 1\"",
     "dev:worker": "concurrently -k -n \"TypeScript,Node\" -c \"yellow.bold,cyan.bold\" \"npm run watch\" \"nodemon worker\"",
     "dev:webhook": "concurrently -k -n \"TypeScript,Node\" -c \"yellow.bold,cyan.bold\" \"npm run watch\" \"nodemon webhook\"",
     "format": "biome format --write .",

packages/cli/src/load-nodes-and-credentials.ts

@@ -26,6 +26,7 @@ import type {
 	LoadedNodesAndCredentials,
 } from 'n8n-workflow';
 import { deepCopy, NodeConnectionTypes, UnexpectedError, UserError } from 'n8n-workflow';
+import { type Stats } from 'node:fs';
 import path from 'path';
 import picocolors from 'picocolors';
 
@@ -532,24 +533,47 @@ export class LoadNodesAndCredentials {
 			}
 
 			const reloader = debounce(async () => {
+				this.logger.info(`Hot reload triggered for ${loader.packageName}`);
+				try {
 					loader.reset();
 					await loader.loadAll();
 					await this.postProcessLoaders();
 					push.broadcast({ type: 'nodeDescriptionUpdated', data: {} });
+				} catch (error) {
+					this.logger.error(`Hot reload failed for ${loader.packageName}`);
+				}
 			}, 100);
 
-			const toWatch = loader.isLazyLoaded
+			// For lazy loaded packages, we need to watch the dist directory
-				? ['**/nodes.json', '**/credentials.json']
+			const watchPath = loader.isLazyLoaded ? path.join(directory, 'dist') : directory;
-				: ['**/*.js', '**/*.json'];
+
-			const files = await glob(toWatch, {
+			// Watch options for chokidar v4
-				cwd: directory,
+			const watchOptions = {
-				ignore: ['node_modules/**'],
-			});
-			const watcher = watch(files, {
-				cwd: directory,
 				ignoreInitial: true,
-			});
+				cwd: directory,
-			watcher.on('add', reloader).on('change', reloader).on('unlink', reloader);
+				// Filter which files to watch based on loader type
+				ignored: (filePath: string, stats?: Stats) => {
+					if (!stats) return false;
+					if (stats.isDirectory()) return false;
+					if (filePath.includes('node_modules')) return true;
+
+					if (loader.isLazyLoaded) {
+						// Only watch nodes.json and credentials.json files
+						const basename = path.basename(filePath);
+						return basename !== 'nodes.json' && basename !== 'credentials.json';
+					}
+
+					// Watch all .js and .json files
+					return !filePath.endsWith('.js') && !filePath.endsWith('.json');
+				},
+			};
+
+			const watcher = watch(watchPath, watchOptions);
+
+			// Watch for file changes and additions
+			// Not watching removals to prevent issues during build processes
+			watcher.on('change', reloader);
+			watcher.on('add', reloader);
 		});
 	}
 }