diff --git a/src/resultStore.js b/src/resultStore.js
index 628587c..2065b83 100644
--- a/src/resultStore.js
+++ b/src/resultStore.js
@@ -1,15 +1,23 @@
 import Database from 'better-sqlite3';
-import { existsSync, mkdirSync, readFileSync, writeFileSync } from 'fs';
+import {
+  copyFileSync,
+  existsSync,
+  mkdirSync,
+  readFileSync,
+  renameSync,
+  unlinkSync,
+  writeFileSync,
+} from 'fs';
 import { fileURLToPath } from 'url';
 import { dirname, join } from 'path';
 
 const __filename = fileURLToPath(import.meta.url);
 const __dirname = dirname(__filename);
 
-const DB_PATH =
-  process.env.APP_DB_PATH ||
-  process.env.RESULTS_DB_PATH ||
-  join(__dirname, '..', 'data', 'results.sqlite');
+const DEFAULT_DB_DIR = join(__dirname, '..', 'data');
+const DEFAULT_DB_PATH = join(DEFAULT_DB_DIR, 'results.db');
+const LEGACY_DB_PATH = join(DEFAULT_DB_DIR, 'results.sqlite');
+const DB_PATH = resolveDbPath();
 const CONFIG_PATH = join(__dirname, '..', 'config.json');
 const MAX_RESULT_RECORDS = 500;
 const DEFAULT_TASK_MODE = 'qwen3.5-plus';
@@ -22,6 +30,55 @@ function clone(value) {
   return JSON.parse(JSON.stringify(value));
 }
 
+function removeFileIfExists(filePath) {
+  if (!existsSync(filePath)) return;
+  unlinkSync(filePath);
+}
+
+function migrateLegacyDbIfNeeded(nextPath, legacyPath) {
+  if (existsSync(nextPath) || !existsSync(legacyPath)) return nextPath;
+
+  const legacyDb = new Database(legacyPath);
+
+  try {
+    legacyDb.pragma('wal_checkpoint(TRUNCATE)');
+  } catch (_error) {
+    // Ignore checkpoint failures and still attempt to switch to single-file mode.
+  }
+
+  legacyDb.pragma('journal_mode = DELETE');
+  legacyDb.close();
+
+  try {
+    renameSync(legacyPath, nextPath);
+  } catch (_error) {
+    copyFileSync(legacyPath, nextPath);
+  }
+
+  removeFileIfExists(`${legacyPath}-shm`);
+  removeFileIfExists(`${legacyPath}-wal`);
+
+  return nextPath;
+}
+
+function resolveDbPath() {
+  const explicitPath = process.env.APP_DB_PATH || process.env.RESULTS_DB_PATH;
+  if (explicitPath) return explicitPath;
+
+  mkdirSync(DEFAULT_DB_DIR, { recursive: true });
+
+  try {
+    return migrateLegacyDbIfNeeded(DEFAULT_DB_PATH, LEGACY_DB_PATH);
+  } catch (error) {
+    if (existsSync(LEGACY_DB_PATH)) {
+      console.warn(`[resultStore] Legacy database migration skipped: ${error.message}`);
+      return LEGACY_DB_PATH;
+    }
+
+    throw error;
+  }
+}
+
 function generateResultId() {
   return `result-${Date.now()}-${Math.random().toString(36).slice(2, 7)}`;
 }
@@ -141,7 +198,13 @@ function getDb() {
 
   mkdirSync(dirname(DB_PATH), { recursive: true });
   db = new Database(DB_PATH);
-  db.pragma('journal_mode = WAL');
+
+  try {
+    db.pragma('journal_mode = DELETE');
+  } catch (error) {
+    console.warn(`[resultStore] Database journal mode unchanged: ${error.message}`);
+  }
+
   return db;
 }