fix(stats): report complete vocabulary totals and new-word history (#202)

src/core/services/immersion-tracker/lexical-rollup-worker.test.ts

@@ -0,0 +1,35 @@
+import assert from 'node:assert/strict';
+import fs from 'node:fs';
+import os from 'node:os';
+import path from 'node:path';
+import test from 'node:test';
+import { areLexicalDailyRollupsReady, getLexicalDailyRollups } from './lexical-rollups';
+import { executeLexicalRollupBackfillTask } from './lexical-rollup-worker';
+import { Database } from './sqlite';
+import { ensureSchema } from './storage';
+
+test('lexical rollup backfill materializes pre-existing vocabulary off the caller DB connection', () => {
+  const directory = fs.mkdtempSync(path.join(os.tmpdir(), 'subminer-lexical-rollup-worker-'));
+  const dbPath = path.join(directory, 'immersion.sqlite');
+  const db = new Database(dbPath);
+
+  try {
+    ensureSchema(db);
+    db.prepare(
+      `INSERT INTO imm_words(headword, word, reading, first_seen, last_seen, frequency)
+       VALUES (?, ?, ?, ?, ?, 1)`,
+    ).run('犬', '犬', 'いぬ', 1_700_000_000, 1_700_000_000);
+    db.exec('DELETE FROM imm_lexical_daily_rollups');
+    db.prepare(`UPDATE imm_rollup_state SET state_value = '0' WHERE state_key = ?`).run(
+      'lexical_daily_rollups_version',
+    );
+
+    executeLexicalRollupBackfillTask(dbPath);
+
+    assert.equal(areLexicalDailyRollupsReady(db), true);
+    assert.equal(getLexicalDailyRollups(db)[0]?.wordCount, 1);
+  } finally {
+    db.close();
+    fs.rmSync(directory, { recursive: true, force: true });
+  }
+});