Remove retired cleanup manifest state

internal/manifest/store_test.go

@@ -6,6 +6,7 @@ import (
 	"errors"
 	"os"
 	"path/filepath"
+	"reflect"
 	"strings"
 	"testing"
 	"time"
@@ -256,6 +257,33 @@ func TestLoadRejectsInvalidManifest(t *testing.T) {
 	}
 }
 
+func TestLocalStoreRejectsRetiredCleanupFieldAndRoundTripsCanonicalV1(t *testing.T) {
+	store := &LocalStore{}
+	canonical := `{"schema_version":"narratio.session-manifest.v1","session_id":"2026-05-03","created_at":"2026-05-03T10:00:00Z","updated_at":"2026-05-03T10:01:00Z","stages":{}}`
+
+	loaded, err := store.LoadReader(context.Background(), strings.NewReader(canonical))
+	if err != nil {
+		t.Fatalf("load canonical manifest: %v", err)
+	}
+	encoded, err := json.Marshal(loaded)
+	if err != nil {
+		t.Fatalf("marshal canonical manifest: %v", err)
+	}
+	roundTripped, err := store.LoadReader(context.Background(), strings.NewReader(string(encoded)))
+	if err != nil {
+		t.Fatalf("reload canonical manifest: %v", err)
+	}
+	if !reflect.DeepEqual(roundTripped, loaded) {
+		t.Fatalf("round-tripped manifest = %#v, want %#v", roundTripped, loaded)
+	}
+
+	retired := strings.TrimSuffix(canonical, "}") + `,"post_publish_cleanup":{"committed_run_id":"20260905T010203Z-a1b2c3d4"}}`
+	_, err = store.LoadReader(context.Background(), strings.NewReader(retired))
+	if err == nil || !strings.Contains(err.Error(), `unknown field "post_publish_cleanup"`) {
+		t.Fatalf("load retired cleanup field error = %v, want strict unknown-field rejection", err)
+	}
+}
+
 func TestLocalStoreRejectsUnsupportedSchemaVersions(t *testing.T) {
 	store := &LocalStore{}
 	now := time.Date(2026, 5, 3, 10, 0, 0, 0, time.UTC)