fix(stats): avoid transient SQLite worker lock

src/core/services/immersion-tracker/storage-session.test.ts

@@ -3,7 +3,7 @@ import fs from 'node:fs';
 import os from 'node:os';
 import path from 'node:path';
 import test from 'node:test';
-import { Database } from './sqlite';
+import { Database, type DatabaseSync } from './sqlite';
 import { getStatsExcludedWords, replaceStatsExcludedWords } from './query-lexical';
 import { finalizeSessionRecord, startSessionRecord } from './session';
 import {
@@ -87,6 +87,29 @@ test('applyPragmas sets the SQLite tuning defaults used by immersion tracking',
   }
 });
 
+test('applyPragmas installs the busy timeout before WAL negotiation', () => {
+  const statements: string[] = [];
+  const db: DatabaseSync = {
+    exec(source) {
+      statements.push(source);
+      return db;
+    },
+    prepare() {
+      throw new Error('not used');
+    },
+    close() {
+      return db;
+    },
+  };
+
+  applyPragmas(db);
+
+  assert.deepEqual(statements.slice(0, 2), [
+    'PRAGMA busy_timeout = 2500',
+    'PRAGMA journal_mode = WAL',
+  ]);
+});
+
 test('ensureSchema creates immersion core tables', () => {
   const dbPath = makeDbPath();
   const db = new Database(dbPath);

src/core/services/immersion-tracker/storage.ts

@@ -315,10 +315,12 @@ function migrateSessionEventTimestampsToText(db: DatabaseSync): void {
 }
 
 export function applyPragmas(db: DatabaseSync): void {
+  // Install the wait policy before WAL negotiation, which can briefly contend with
+  // another connection closing or checkpointing the same database.
+  db.exec('PRAGMA busy_timeout = 2500');
   db.exec('PRAGMA journal_mode = WAL');
   db.exec('PRAGMA synchronous = NORMAL');
   db.exec('PRAGMA foreign_keys = ON');
-  db.exec('PRAGMA busy_timeout = 2500');
   db.exec(`PRAGMA journal_size_limit = ${WAL_JOURNAL_SIZE_LIMIT_BYTES}`);
 }