improve superseeding, fix linux persistence stuff

Overlord-Client/cmd/agent/main_test.go

@@ -5,6 +5,8 @@ import (
 	"time"
 
 	rt "overlord-client/cmd/agent/runtime"
+
+	"nhooyr.io/websocket"
 )
 
 func TestMinDuration(t *testing.T) {
@@ -15,3 +17,15 @@ func TestMinDuration(t *testing.T) {
 		t.Fatalf("expected shorter duration returned, got %s", got)
 	}
 }
+
+func TestIsSupersededError(t *testing.T) {
+	if !isSupersededError(&websocket.CloseError{Code: supersededCloseCode, Reason: "superseded"}) {
+		t.Fatal("expected close code 4004 to be treated as superseded")
+	}
+	if !isSupersededError(&websocket.CloseError{Code: websocket.StatusNormalClosure, Reason: "superseded"}) {
+		t.Fatal("expected superseded reason to be treated as superseded")
+	}
+	if isSupersededError(&websocket.CloseError{Code: websocket.StatusNormalClosure, Reason: "bye"}) {
+		t.Fatal("normal closure should not be treated as superseded")
+	}
+}