perf: change db to WAL mode (#3140)

src/backup_manager.ts

@@ -296,12 +296,14 @@ export class BackupManager {
   ): Promise<void> {
     logger.debug(`Backing up SQLite database: ${sourcePath} → ${destPath}`);
     const sourceDb = new Database(sourcePath, {
-      readonly: true,
       timeout: 10000,
     });
 
     try {
-      // This is safe even if other connections are active
+      // Flush any pending WAL data into the main database file before backing up.
+      // This ensures the backup captures all committed data, even if a previous
+      // session crashed and left un-checkpointed writes in the WAL.
+      sourceDb.pragma("wal_checkpoint(TRUNCATE)");
       await sourceDb.backup(destPath);
       logger.info("Database backup completed successfully");
     } catch (error) {

src/db/index.ts

@@ -52,6 +52,15 @@ export function initializeDatabase(): BetterSQLite3Database<typeof schema> & {
   const sqlite = new Database(dbPath, { timeout: 10000 });
   sqlite.pragma("foreign_keys = ON");
 
+  try {
+    sqlite.pragma("journal_mode = WAL");
+  } catch (error) {
+    logger.warn(
+      "Could not enable WAL mode, falling back to default journal mode:",
+      error,
+    );
+  }
+
   _db = drizzle(sqlite, { schema });
 
   try {