diff --git a/internal/validation/wave4_schema_validator_test.go b/internal/validation/wave4_schema_validator_test.go
new file mode 100644
index 000000000..a955a5038
--- /dev/null
+++ b/internal/validation/wave4_schema_validator_test.go
@@ -0,0 +1,42 @@
+package validation
+
+import (
+	"testing"
+)
+
+func TestWave4TenantIDSanitization(t *testing.T) {
+	isValidTenantID := func(tenant string) bool {
+		if len(tenant) == 0 || len(tenant) > 64 {
+			return false
+		}
+		for _, r := range tenant {
+			if !((r >= 'a' && r <= 'z') || (r >= '0' && r <= '9') || r == '-' || r == '_') {
+				return false
+			}
+		}
+		return true
+	}
+
+	if !isValidTenantID("t_org_prod_99") {
+		t.Error("expected valid tenant ID")
+	}
+	if isValidTenantID("invalid tenant with spaces") {
+		t.Error("expected invalid tenant ID with spaces")
+	}
+	if isValidTenantID("") {
+		t.Error("expected invalid empty tenant ID")
+	}
+}
+
+func TestWave4DepthLimitBoundary(t *testing.T) {
+	checkGraphDepth := func(currentDepth int, maxDepth int) bool {
+		return currentDepth <= maxDepth && currentDepth >= 0
+	}
+
+	if !checkGraphDepth(15, 30) {
+		t.Error("depth 15 of 30 should be allowed")
+	}
+	if checkGraphDepth(31, 30) {
+		t.Error("depth 31 of 30 should exceed maximum recursion depth")
+	}
+}