1 files changed, 40 insertions, 0 deletions
diff --git a/internal/game/snapshot_render_guard_test.go b/internal/game/snapshot_render_guard_test.go
new file mode 100644
index 0000000..83833d5
--- /dev/null
+++ b/internal/game/snapshot_render_guard_test.go
@@ -0,0 +1,40 @@
+package game
+
+// Guard for the last per-game presentation seam: the Snapshot marker interface
+// guarantees an event carries a structured view, but renderCasinoSnapshot's
+// type switch silently returns "" for a snapshot it does not know. This
+// source-level test pairs every `func (*X) snapshot() {}` in the casino package
+// with a `case *casino.X:` in the renderer, so adding a game cannot silently
+// drop its view (the text message would still appear, hiding the loss).
+
+import (
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+	"testing"
+)
+
+func TestEveryCasinoSnapshotHasARenderer(t *testing.T) {
+	typesSrc, err := os.ReadFile(filepath.Join("..", "casino", "types.go"))
+	if err != nil {
+		t.Fatalf("read casino types: %v", err)
+	}
+	renderSrc, err := os.ReadFile("casino.go")
+	if err != nil {
+		t.Fatalf("read renderer: %v", err)
+	}
+
+	re := regexp.MustCompile(`func \(\*(\w+)\) snapshot\(\)`)
+	matches := re.FindAllStringSubmatch(string(typesSrc), -1)
+	if len(matches) == 0 {
+		t.Fatal("no Snapshot implementations found in casino/types.go")
+	}
+	for _, m := range matches {
+		name := m[1]
+		want := "case *casino." + name + ":"
+		if !strings.Contains(string(renderSrc), want) {
+			t.Errorf("snapshot %s has no renderer: add `%s` to renderCasinoSnapshot", name, want)
+		}
+	}
+}