diff --git a/codex/rules/allow.rules b/codex/rules/allow.rules
index 5f56cb1..3f7a4e5 100644
--- a/codex/rules/allow.rules
+++ b/codex/rules/allow.rules
@@ -206,6 +206,12 @@ prefix_rule(
     justification = "ローカル操作は安全"
 )
 
+prefix_rule(
+    pattern = ["bun", "install", "--frozen-lockfile"],
+    decision = "allow",
+    justification = "ロックファイルを変更しない依存関係のインストールは安全"
+)
+
 prefix_rule(
     pattern = ["bundle", ["exec", "install"]],
     decision = "allow",