fix: move handledFiles from module scope to Walker instance

CHANGELOG.md

@@ -1,5 +1,13 @@
 # Changelog
 
+## 1.5.3 - 2026-03-27
+
+### Bug fixes
+
+- Fix non-deterministic warning counts caused by two related bugs in the Walker:
+  1. The module-level `handledFiles` Set persisted across Walker instances, so when the file cache expired mid-run, re-walking produced an empty file list. Moved `handledFiles` into the Walker instance.
+  2. `shouldSkip()` created a new Walker on every call and depended solely on the disk cache, which could expire mid-run. Added an in-memory cache (`inMemoryCache` Map) that persists for the entire ESLint process, so `shouldSkip()` always sees the complete file list regardless of disk cache TTL.
+
 ## 1.5.2 - 2024-10-15
 
 ### Bug fixes

lib/util/walker.js

@@ -96,8 +96,6 @@ function isNpmDependency(importPath) {
   return !appFileImport.includes(importPath[0]);
 }
 
-const handledFiles = new Set();
-
 function getAbsFilePath(filePath) {
   // some files have no ext or are only the ext (.gitignore, .editorconfig, etc.)
   const existingExt =
@@ -114,7 +112,7 @@ function getAbsFilePath(filePath) {
   return filePath;
 }
 
-function handleFile(_filePath, appPath, onFile, cachedParsedFile) {
+function handleFile(_filePath, appPath, onFile, cachedParsedFile, handledFiles) {
   const filePath = getAbsFilePath(_filePath);
   if (!filePath) {
     return;
@@ -149,11 +147,11 @@ function handleFile(_filePath, appPath, onFile, cachedParsedFile) {
       return path.resolve(path.dirname(filePath), source);
     })
     .forEach((importPath) => {
-      handleFile(importPath, appPath, onFile, cachedParsedFile);
+      handleFile(importPath, appPath, onFile, cachedParsedFile, handledFiles);
     });
 }
 
-function handleFolder(folderPath, appPath, archList, onFile, cachedParsedFile) {
+function handleFolder(folderPath, appPath, archList, onFile, cachedParsedFile, handledFiles) {
   const dirents = fs.readdirSync(folderPath, { withFileTypes: true });
   for (let i = 0; i < dirents.length; i += 1) {
     if (dirents[i].isDirectory()) {
@@ -163,12 +161,13 @@ function handleFolder(folderPath, appPath, archList, onFile, cachedParsedFile) {
           appPath,
           archList,
           onFile,
-          cachedParsedFile
+          cachedParsedFile,
+          handledFiles
         );
       }
     } else if (dirents[i].isFile()) {
       const filePath = path.resolve(folderPath, dirents[i].name);
-      handleFile(filePath, appPath, onFile, cachedParsedFile);
+      handleFile(filePath, appPath, onFile, cachedParsedFile, handledFiles);
     }
   }
 }
@@ -203,15 +202,15 @@ function getInitFolder(context) {
 }
 
 function shouldSkip(context) {
-  const walker = new Walker(getInitFolder(context));
+  const appPath = getInitFolder(context);
 
   const realPath = fs.realpathSync.native(context.physicalFilename);
   const parsedFiles = process.env.METEOR_ESLINT_PLUGIN_FILES
       ? process.env.METEOR_ESLINT_PLUGIN_FILES.split(',').reduce(
           (acc, item) => ({ ...acc, [item]: true }),
           {},
       )
-      : walker.cachedParsedFile;
+      : Walker.getParsedFiles(appPath);
 
   if (!Object.keys(parsedFiles).length || !(realPath in parsedFiles)) {
     debug('Skipping file', realPath);
@@ -235,17 +234,36 @@ const cacheExistsAndIsStillValid = (filePath) => {
   return seconds <= EXPIRES_CACHE_IN_SECONDS;
 }
 
+// In-memory cache keyed by appPath. Survives the entire ESLint process so
+// shouldSkip() never depends on the disk cache's TTL within a single run.
+const inMemoryCache = new Map();
 
 class Walker {
   cachedParsedFile;
   appPath;
+  handledFiles;
 
   filePath() {
     return path.join(this.appPath, '.eslint-meteor-files');
   }
 
+  static getParsedFiles(appPath) {
+    if (inMemoryCache.has(appPath)) {
+      return inMemoryCache.get(appPath);
+    }
+    const walker = new Walker(appPath);
+    return walker.cachedParsedFile;
+  }
+
   constructor(appPath) {
     this.appPath = appPath;
+    this.handledFiles = new Set();
+
+    if (inMemoryCache.has(appPath)) {
+      this.cachedParsedFile = inMemoryCache.get(appPath);
+      return;
+    }
+
     const useCache = cacheExistsAndIsStillValid(this.filePath());
     if (!useCache) {
       debug('Cache is not going to be used');
@@ -269,8 +287,10 @@ class Walker {
           path.join(this.appPath, meteor.mainModule.server),
           this.appPath,
           onFile,
-          this.cachedParsedFile
+          this.cachedParsedFile,
+          this.handledFiles
         );
+        inMemoryCache.set(this.appPath, this.cachedParsedFile);
         fs.writeFileSync(this.filePath(), JSON.stringify(this.cachedParsedFile));
         return;
       }
@@ -282,9 +302,11 @@ class Walker {
       this.appPath,
       archList,
       onFile,
-      this.cachedParsedFile
+      this.cachedParsedFile,
+      this.handledFiles
     );
 
+    inMemoryCache.set(this.appPath, this.cachedParsedFile);
     fs.writeFileSync(this.filePath(), JSON.stringify(this.cachedParsedFile));
   }
 

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@quave/eslint-plugin-meteor-quave",
-  "version": "1.5.2",
+  "version": "1.5.3",
   "description": "Quave linting rules for ESLint",
   "main": "lib/index.js",
   "scripts": {