fix: 修复写队列 busy 恢复、关闭安全、备份与配置构建问题

cmd/nixmsg/backup.go

@@ -19,6 +19,25 @@ func cmdBackup(args []string) error {
 	if err != nil {
 		return err
 	}
+	dataAbs, err := filepath.Abs(cfg.DataDir)
+	if err != nil {
+		return fmt.Errorf("resolve data_dir: %w", err)
+	}
+	srcAbs, err := filepath.Abs(filepath.Join(dataAbs, store.DBFileName))
+	if err != nil {
+		return err
+	}
+	st, err := os.Stat(srcAbs)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return fmt.Errorf("database not found: %s", srcAbs)
+		}
+		return fmt.Errorf("stat database %s: %w", srcAbs, err)
+	}
+	if st.IsDir() {
+		return fmt.Errorf("database path is a directory: %s", srcAbs)
+	}
+
 	if dir := filepath.Dir(outPath); dir != "" && dir != "." {
 		if mkErr := os.MkdirAll(dir, 0o755); mkErr != nil {
 			return fmt.Errorf("mkdir backup dir: %w", mkErr)
@@ -29,8 +48,7 @@ func cmdBackup(args []string) error {
 		return err
 	}
 	ctx := context.Background()
-	// 对运行中的库：单独打开写连接执行 VACUUM INTO（可与 serve 并存，WAL 下安全）。
-	write, err := store.OpenWriter(cfg.DataDir, cfg.SQLiteSynchronous)
+	write, err := store.OpenExistingWriter(dataAbs, cfg.SQLiteSynchronous)
 	if err != nil {
 		return err
 	}
@@ -38,7 +56,10 @@ func cmdBackup(args []string) error {
 	if err := store.VacuumInto(ctx, write, filepath.ToSlash(absOut)); err != nil {
 		return err
 	}
-	fmt.Fprintf(os.Stderr, "backup written to %s\n", absOut)
+	if chErr := os.Chmod(absOut, 0o600); chErr != nil {
+		return fmt.Errorf("chmod backup: %w", chErr)
+	}
+	fmt.Fprintf(os.Stderr, "backup written from %s to %s\n", srcAbs, absOut)
 	return nil
 }