From 5f79c39687c535f370dfa894b0bc714dce285df8 Mon Sep 17 00:00:00 2001
From: Nguyen Thanh Dat <ntdat812.dev@gmail.com>
Date: Tue, 25 Aug 2026 18:34:12 +0700
Subject: [PATCH] test(locale-agents): derive the file lists instead of
 accumulating them

Review feedback on #2879, citing rules/common/coding-style.md ("Immutability
(CRITICAL): ALWAYS create new objects, NEVER mutate existing ones"). Build one
list of locale entries, then derive the matched and orphaned sets from it with
filter/map, and build the canonical Map the same way.

Behaviour is unchanged and both mutations still fail: reintroducing the drift in
one locale file gives `Passed: 4, Failed: 3`, an orphan gives `Passed: 6,
Failed: 1`, both exit 1.
---
 tests/ci/locale-agent-frontmatter.test.js | 31 +++++++++++++----------
 1 file changed, 17 insertions(+), 14 deletions(-)

diff --git a/tests/ci/locale-agent-frontmatter.test.js b/tests/ci/locale-agent-frontmatter.test.js
index 26dc92228..454e1e002 100644
--- a/tests/ci/locale-agent-frontmatter.test.js
+++ b/tests/ci/locale-agent-frontmatter.test.js
@@ -76,23 +76,26 @@ function runTest(name, fn) {
 function main() {
   console.log('\n=== Testing locale agent frontmatter against canonical ===\n');
 
-  const canonical = new Map();
-  for (const file of fs.readdirSync(AGENTS_DIR).filter(f => f.endsWith('.md'))) {
-    const fields = frontmatter(path.join(AGENTS_DIR, file));
-    if (fields) canonical.set(file, fields);
-  }
+  const canonical = new Map(
+    fs
+      .readdirSync(AGENTS_DIR)
+      .filter(file => file.endsWith('.md'))
+      .map(file => [file, frontmatter(path.join(AGENTS_DIR, file))])
+      .filter(([, fields]) => fields !== null)
+  );
 
   const rel = filePath => path.relative(REPO_ROOT, filePath).split(path.sep).join('/');
 
-  const localeFiles = [];
-  const orphans = [];
-  for (const dir of localeAgentDirs()) {
-    for (const file of fs.readdirSync(dir).filter(f => f.endsWith('.md'))) {
-      const filePath = path.join(dir, file);
-      if (canonical.has(file)) localeFiles.push({ file, filePath });
-      else orphans.push(rel(filePath));
-    }
-  }
+  const localeEntries = localeAgentDirs().flatMap(dir =>
+    fs
+      .readdirSync(dir)
+      .filter(file => file.endsWith('.md'))
+      .map(file => ({ file, filePath: path.join(dir, file) }))
+  );
+  const localeFiles = localeEntries.filter(({ file }) => canonical.has(file));
+  const orphans = localeEntries
+    .filter(({ file }) => !canonical.has(file))
+    .map(({ filePath }) => rel(filePath));
 
   const tests = [
     ['there are locale agent docs to check', () => {