diff --git a/vcs/interfaces.go b/vcs/interfaces.go
index 62642f1..ecada13 100644
--- a/vcs/interfaces.go
+++ b/vcs/interfaces.go
@@ -1,3 +1,6 @@
+// Package vcs defines the shared VCS client interface and supporting types.
+// Platform adapters (gitea, github) implement these interfaces so the core
+// review logic can work with any VCS platform without platform-specific code.
 package vcs
 
 import "context"