diff --git a/config.yaml.example b/config.yaml.example
index aa2f2c6..5367ec5 100644
--- a/config.yaml.example
+++ b/config.yaml.example
@@ -3,7 +3,7 @@
 
 listen_addr: ":8080"          # HTTP listen address
 audience: "trust.n1ko.dev"    # audience bound into auth assertions
-data_dir: ""                  # "" = in-memory; set a path to persist objects
+# data_dir: "data"             # uncomment to persist objects (default "data"); "" = in-memory
 log_level: "info"             # debug | info | warn | error
 
 # Per-IP fixed-window rate limits.
diff --git a/internal/server/config.go b/internal/server/config.go
index f5a4757..95aec65 100644
--- a/internal/server/config.go
+++ b/internal/server/config.go
@@ -52,6 +52,7 @@ func DefaultConfig() Config {
 	return Config{
 		ListenAddr:     ":8080",
 		Audience:       "trust.n1ko.dev",
+		DataDir:        "data", // persist objects; "" would be in-memory only
 		LogLevel:       "info",
 		PutLimit:       60,
 		PutWindow:      time.Minute,