From 96cd75ed81a25d0e21e8f50e5f803b726a8bdddb Mon Sep 17 00:00:00 2001
From: tiennm99 <tiennm99@outlook.com>
Date: Thu, 9 Apr 2026 09:28:46 +0700
Subject: [PATCH] add code guideline: prefer established libraries over custom
 utils

---
 CLAUDE.md | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/CLAUDE.md b/CLAUDE.md
index d43c01c..5ca650e 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -74,6 +74,12 @@ Detailed docs live in `docs/`:
 - `docs/system-architecture.md` — Entry points, data flow, KV schema, queue, security
 - `docs/feature-decisions.md` — Evaluated features and rationale for decisions
 
+## Code Guidelines
+
+Prefer well-established npm packages over hand-written utilities for common operations
+(e.g., date formatting, validation, string manipulation). Only write custom utils when
+the logic is trivial (< 5 lines) or platform-specific (e.g., CF Workers crypto APIs).
+
 ## README Guidelines
 
 Keep `README.md` clean and focused: project intro, features, commands, quick start, and links to docs.