fix(json): add retry logic for Windows EPERM errors during file writes

Windows can have transient file locking issues in temp directories, causing
EPERM errors when writing files. This adds exponential backoff retry logic
to handle these transient failures.

- Add retryWrite() helper with exponential backoff (10ms, 20ms, 40ms)
- Retry on EPERM and EBUSY errors up to 3 times
- Fixes flaky test: 'should preserve line endings' on Windows CI

Author: jdalton

src/json/edit.ts

@@ -41,6 +41,44 @@ function getFs() {
   return _fs as typeof import('node:fs')
 }
 
+/**
+ * Retry a file write operation with exponential backoff on Windows EPERM errors.
+ * Windows can have transient file locking issues with temp directories.
+ * @private
+ */
+async function retryWrite(
+  filepath: string,
+  content: string,
+  retries = 3,
+  baseDelay = 10,
+): Promise<void> {
+  const { promises: fsPromises } = getFs()
+
+  for (let attempt = 0; attempt <= retries; attempt++) {
+    try {
+      // eslint-disable-next-line no-await-in-loop
+      await fsPromises.writeFile(filepath, content)
+      return
+    } catch (err) {
+      const isLastAttempt = attempt === retries
+      const isEperm =
+        err instanceof Error &&
+        'code' in err &&
+        (err.code === 'EPERM' || err.code === 'EBUSY')
+
+      // Only retry on Windows EPERM/EBUSY errors, and not on the last attempt
+      if (!isEperm || isLastAttempt) {
+        throw err
+      }
+
+      // Exponential backoff: 10ms, 20ms, 40ms
+      const delay = baseDelay * 2 ** attempt
+      // eslint-disable-next-line no-await-in-loop
+      await new Promise(resolve => setTimeout(resolve, delay))
+    }
+  }
+}
+
 /**
  * Parse JSON content and extract formatting metadata.
  * @private
@@ -216,9 +254,8 @@ export function getEditableJsonClass<
         // Generate file content
         const fileContent = stringifyWithFormatting(sortedContent, formatting)
 
-        // Save to disk
-        const { promises: fsPromises } = getFs()
-        await fsPromises.writeFile(this.filename, fileContent)
+        // Save to disk with retry logic for Windows file locking issues
+        await retryWrite(this.filename, fileContent)
         this._readFileContent = fileContent
         this._readFileJson = parseJson(fileContent)
         return true