remove pathTruncationLength + add error prefix

Author: gaojude

packages/next/errors.json

@@ -627,8 +627,8 @@
   "626": "Intercepting routes are not supported with static export.\\nRead more: https://nextjs.org/docs/app/building-your-application/deploying/static-exports#unsupported-features",
   "627": "cacheLife() is only available with the experimental.useCache config.",
   "628": "cacheTag() is only available with the experimental.useCache config.",
-  "629": "Invariant: Module is recorded after the report is generated. This is a Next.js internal bug.",
-  "630": "Invariant: Module is missing a required debugId. This is a Next.js internal bug.",
-  "631": "Invariant: Unable to find the start time for a module build. This is a Next.js internal bug.",
-  "632": "Invariant: Circular dependency detected in module graph. This is a Next.js internal bug."
+  "629": "Invariant (SlowModuleDetectionPlugin): Unable to find the start time for a module build. This is a Next.js internal bug.",
+  "630": "Invariant (SlowModuleDetectionPlugin): Module is recorded after the report is generated. This is a Next.js internal bug.",
+  "631": "Invariant (SlowModuleDetectionPlugin): Circular dependency detected in module graph. This is a Next.js internal bug.",
+  "632": "Invariant (SlowModuleDetectionPlugin): Module is missing a required debugId. This is a Next.js internal bug."
 }

packages/next/src/build/webpack-config.ts

@@ -1950,7 +1950,9 @@ export default async function getBaseWebpackConfig(
           require('./webpack/plugins/slow-module-detection-plugin') as typeof import('./webpack/plugins/slow-module-detection-plugin')
         ).default({
           compilerType,
-          ...config.experimental.slowModuleDetection,
+          ...(typeof config.experimental.slowModuleDetection === 'object'
+            ? config.experimental.slowModuleDetection
+            : {}),
         }),
     ].filter(Boolean as any as ExcludesFalse),
   }

packages/next/src/build/webpack/plugins/slow-module-detection-plugin.ts

@@ -12,22 +12,21 @@ const TreeSymbols = {
 
 const DEFAULT_SLOW_MODULE_THRESHOLD_MS = 500
 
-const DEFAULT_PATH_TRUNCATION_LENGTH = 100
+const PATH_TRUNCATION_LENGTH = 100
 
 // Matches node_modules paths, including pnpm-style paths
 const NODE_MODULES_PATH_PATTERN = /node_modules(?:\/\.pnpm)?\/(.*)/
 
 interface ModuleBuildTimeAnalyzerOptions {
   compilerType: CompilerNameValues
   slowModuleThresholdMs?: number
-  pathTruncationLength?: number
 }
 
 const getModuleIdentifier = (module: Module): string => {
   const debugId = module.debugId
   if (!debugId) {
     throw new Error(
-      `Invariant: Module is missing a required debugId. This is a Next.js internal bug.`
+      `Invariant (SlowModuleDetectionPlugin): Module is missing a required debugId. This is a Next.js internal bug.`
     )
   }
   return String(debugId)
@@ -67,19 +66,16 @@ class ModuleBuildTimeAnalyzer {
   private moduleChildren = new Map<Module, Map<string, Module>>()
   private isFinalized = false
   private slowModuleThresholdMs: number
-  private pathTruncationLength: number
 
   constructor(private options: ModuleBuildTimeAnalyzerOptions) {
     this.slowModuleThresholdMs =
       options.slowModuleThresholdMs ?? DEFAULT_SLOW_MODULE_THRESHOLD_MS
-    this.pathTruncationLength =
-      options.pathTruncationLength ?? DEFAULT_PATH_TRUNCATION_LENGTH
   }
 
   recordModuleBuildTime(module: Module, duration: number) {
     if (this.isFinalized) {
       throw new Error(
-        `Invariant: Module is recorded after the report is generated. This is a Next.js internal bug.`
+        `Invariant (SlowModuleDetectionPlugin): Module is recorded after the report is generated. This is a Next.js internal bug.`
       )
     }
 
@@ -116,7 +112,7 @@ class ModuleBuildTimeAnalyzer {
         if (!issuerModule) break
         if (visitedModules.has(issuerModule)) {
           throw new Error(
-            `Invariant: Circular dependency detected in module graph. This is a Next.js internal bug.`
+            `Invariant (SlowModuleDetectionPlugin): Circular dependency detected in module graph. This is a Next.js internal bug.`
           )
         }
         chain.push(issuerModule)
@@ -164,13 +160,10 @@ class ModuleBuildTimeAnalyzer {
     )
 
     // Truncates long paths by keeping start and end portions
-    const truncatePath = (
-      path: string,
-      maxLength = this.pathTruncationLength
-    ): string => {
-      if (path.length <= maxLength) return path
-      const startSegment = path.slice(0, maxLength / 3)
-      const endSegment = path.slice((-maxLength * 2) / 3)
+    const truncatePath = (path: string): string => {
+      if (path.length <= PATH_TRUNCATION_LENGTH) return path
+      const startSegment = path.slice(0, PATH_TRUNCATION_LENGTH / 3)
+      const endSegment = path.slice((-PATH_TRUNCATION_LENGTH * 2) / 3)
       return `${startSegment}...${endSegment}`
     }
 
@@ -241,7 +234,7 @@ export default class SlowModuleDetectionPlugin {
         const startTime = moduleBuildStartTimes.get(module)
         if (!startTime) {
           throw new Error(
-            `Invariant: Unable to find the start time for a module build. This is a Next.js internal bug.`
+            `Invariant (SlowModuleDetectionPlugin): Unable to find the start time for a module build. This is a Next.js internal bug.`
           )
         }
         analyzer.recordModuleBuildTime(module, performance.now() - startTime)

packages/next/src/server/config-schema.ts

@@ -446,8 +446,7 @@ export const configSchema: zod.ZodType<NextConfig> = z.lazy(() =>
         useCache: z.boolean().optional(),
         slowModuleDetection: z
           .object({
-            slowModuleThresholdMs: z.number().optional(),
-            pathTruncationLength: z.number().optional(),
+            slowModuleThresholdMs: z.number().positive().optional(),
           })
           .optional(),
       })

packages/next/src/server/config-shared.ts

@@ -620,14 +620,10 @@ export interface ExperimentalConfig {
     /**
      * Time threshold in milliseconds for considering a module "slow".
      * Modules taking longer than this to build will be reported.
+     *
+     * @default 500
      */
     slowModuleThresholdMs?: number
-
-    /**
-     * Maximum length for displayed module paths in the build report.
-     * Longer paths will be truncated.
-     */
-    pathTruncationLength?: number
   }
 }
 

test/development/slow-module-detection/next.config.js

@@ -1,8 +1,7 @@
 module.exports = {
   experimental: {
     slowModuleDetection: {
-      slowModuleThresholdMs: 50, // Lower threshold for testing
-      pathTruncationLength: 50,
+      slowModuleThresholdMs: 50,
     },
   },
 }