diff --git a/.env.example b/.env.example
index fdfbf9f..d97cbf5 100644
--- a/.env.example
+++ b/.env.example
@@ -25,3 +25,8 @@ DB_POOL_SIZE=20
 
 # SSR page cache duration in seconds (default: 3600)
 SSR_CACHE_SECS=3600
+
+# Image serving cache headers
+# Uploaded image assets are served with Cache-Control: public, max-age=31536000, immutable.
+# Processed variants (?w=, ?format=, etc.) are cached for 24 hours.
+# To force browsers to refresh, change the URL or restart the server.