lib/cli/create_db: make WAL mode optional

lib/_data_ingestion/open_local_db.dart

@@ -13,6 +13,7 @@ Future<Database> openLocalDb({
   String? jadbPath,
   bool readWrite = false,
   bool assertTablesExist = true,
+  bool walMode = false,
 }) async {
   libsqlitePath ??= Platform.environment['LIBSQLITE_PATH'];
   jadbPath ??= Platform.environment['JADB_PATH'];
@@ -42,7 +43,9 @@ Future<Database> openLocalDb({
     jadbPath,
     options: OpenDatabaseOptions(
       onConfigure: (db) async {
-        await db.execute("PRAGMA journal_mode = WAL");
+        if (walMode) {
+          await db.execute("PRAGMA journal_mode = WAL");
+        }
         await db.execute("PRAGMA foreign_keys = ON");
       },
       readOnly: !readWrite,

lib/cli/commands/create_db.dart

@@ -12,6 +12,16 @@ class CreateDb extends Command {
 
   CreateDb() {
     addLibsqliteArg(argParser);
+    argParser.addFlag(
+      'wal',
+      help:
+          '''Whether to use Write-Ahead Logging (WAL) mode.
+
+          This is recommended for better performance, but may not be used with
+          the readonly NixOS store.
+      ''',
+      defaultsTo: false,
+    );
   }
 
   Future<void> run() async {
@@ -22,6 +32,7 @@ class CreateDb extends Command {
 
     final db = await openLocalDb(
       libsqlitePath: argResults!.option('libsqlite')!,
+      walMode: argResults!.flag('wal'),
       readWrite: true,
     );