diff --git a/hub/internal/configgen/configgen_debug_test.go b/hub/internal/configgen/configgen_debug_test.go
new file mode 100644
index 0000000..4c597eb
--- /dev/null
+++ b/hub/internal/configgen/configgen_debug_test.go
@@ -0,0 +1,40 @@
+package configgen
+
+import (
+	"strings"
+	"testing"
+
+	"gitea.dooplex.hu/admin/felhom-hub/internal/store"
+)
+
+// The remote debug-mode toggle (hub v0.42.0) relies on this integration: a customer ConfigJSON carrying
+// logging.level=debug must deep-merge OVER the template default into the generated controller.yaml, so the
+// controller's isDebug() (Logging.Level=="debug") lights up the /debug menu + verbose log. Verified live on
+// the demo box (2026-07-10): its controller.yaml carries `logging.level: info` — the exact merge target this
+// pins. Without this leg the hub toggle would be a silent no-op.
+func TestGenerate_DebugLevelOverride(t *testing.T) {
+	const tmpl = "logging:\n  level: info\n"
+
+	// Override present → the generated YAML carries level: debug, and the info default is gone.
+	dbg, err := Generate(tmpl, &store.CustomerConfig{
+		CustomerID: "c1", ConfigJSON: `{"logging":{"level":"debug"}}`,
+	})
+	if err != nil {
+		t.Fatalf("generate (debug): %v", err)
+	}
+	if !strings.Contains(dbg, "level: debug") {
+		t.Fatalf("logging.level=debug override did not reach controller.yaml:\n%s", dbg)
+	}
+	if strings.Contains(dbg, "level: info") {
+		t.Fatalf("the info default should have been overridden by debug:\n%s", dbg)
+	}
+
+	// No override → the template default (info) stands, debug absent.
+	def, err := Generate(tmpl, &store.CustomerConfig{CustomerID: "c1", ConfigJSON: "{}"})
+	if err != nil {
+		t.Fatalf("generate (default): %v", err)
+	}
+	if !strings.Contains(def, "level: info") || strings.Contains(def, "level: debug") {
+		t.Fatalf("no override should leave level: info intact:\n%s", def)
+	}
+}