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

stats/src/lib/api-client.ts

@@ -100,6 +100,8 @@ export const apiClient = {
   getSessionKnownWordsTimeline: (id: number) =>
     fetchJson('sessionKnownWordsTimeline', `/api/stats/sessions/${id}/known-words-timeline`),
   getVocabulary: (limit = 100) => fetchJson('vocabulary', `/api/stats/vocabulary?limit=${limit}`),
+  getVocabularySummary: () => fetchJson('vocabularySummary', '/api/stats/vocabulary/summary'),
+  getVocabularyCharts: () => fetchJson('vocabularyCharts', '/api/stats/vocabulary/charts'),
   getExcludedWords: () => fetchJson('excludedWords', '/api/stats/excluded-words'),
   setExcludedWords: async (words: StatsExcludedWord[]): Promise<void> => {
     await fetchResponse('/api/stats/excluded-words', {

stats/src/lib/formatters.test.ts

@@ -1,7 +1,12 @@
 import assert from 'node:assert/strict';
 import test from 'node:test';
 
-import { epochMsFromDbTimestamp, formatRelativeDate, formatSessionDayLabel } from './formatters';
+import {
+  epochDayToDate,
+  epochMsFromDbTimestamp,
+  formatRelativeDate,
+  formatSessionDayLabel,
+} from './formatters';
 
 const FIXED_NOW = new Date(2026, 2, 16, 12, 0, 0).getTime();
 
@@ -108,6 +113,19 @@ test('epochMsFromDbTimestamp keeps ms timestamps as-is', () => {
   assert.equal(epochMsFromDbTimestamp(1_700_000_000_000), 1_700_000_000_000);
 });
 
+test('epochDayToDate preserves the calendar day west of UTC', () => {
+  const previousTimezone = process.env.TZ;
+  process.env.TZ = 'America/Los_Angeles';
+  try {
+    const epochDay = Math.floor(Date.UTC(2026, 2, 16) / 86_400_000);
+    const date = epochDayToDate(epochDay);
+    assert.deepEqual([date.getFullYear(), date.getMonth(), date.getDate()], [2026, 2, 16]);
+  } finally {
+    if (previousTimezone === undefined) delete process.env.TZ;
+    else process.env.TZ = previousTimezone;
+  }
+});
+
 test('formatSessionDayLabel formats today and yesterday', () => {
   withFixedNow((now) => {
     const oneDayMs = 24 * 60 * 60_000;

stats/src/lib/formatters.ts

@@ -38,7 +38,8 @@ export function formatRelativeDate(ms: number): string {
 }
 
 export function epochDayToDate(epochDay: number): Date {
-  return new Date(epochDay * 86_400_000);
+  const utcDate = new Date(epochDay * 86_400_000);
+  return new Date(utcDate.getUTCFullYear(), utcDate.getUTCMonth(), utcDate.getUTCDate());
 }
 
 export function localDayFromMs(ms: number): number {

stats/src/lib/vocabulary-tab.test.ts

@@ -6,6 +6,7 @@ import { fileURLToPath } from 'node:url';
 const VOCABULARY_TAB_PATH = fileURLToPath(
   new URL('../components/vocabulary/VocabularyTab.tsx', import.meta.url),
 );
+const VOCABULARY_HOOK_PATH = fileURLToPath(new URL('../hooks/useVocabulary.ts', import.meta.url));
 
 test('VocabularyTab declares all hooks before loading and error early returns', () => {
   const source = fs.readFileSync(VOCABULARY_TAB_PATH, 'utf8');
@@ -20,15 +21,32 @@ test('VocabularyTab declares all hooks before loading and error early returns',
   assert.deepEqual(hooksAfterLoadingGuard ?? [], []);
 });
 
-test('VocabularyTab memoizes summary and known-word aggregate calculations', () => {
+test('VocabularyTab uses uncapped server-side data for its charts and card totals', () => {
   const source = fs.readFileSync(VOCABULARY_TAB_PATH, 'utf8');
 
+  assert.match(source, /\} = useVocabulary\(\);/);
+  assert.match(source, /charts\?\.topWordsWithoutNames/);
+  assert.match(source, /charts\?\.newWordsTimelineWithoutNames/);
+  assert.doesNotMatch(source, /buildVocabularySummary\(/);
+  assert.match(source, /uniqueWords: summary\?\.uniqueWordsWithoutNames \?\? 0/);
+  assert.match(source, /uniqueWords: summary\?\.uniqueWords \?\? 0/);
+  assert.match(source, /value=\{summary \? formatNumber\(summary\.uniqueKanji\) : '…'\}/);
+});
+
+test('VocabularyTab surfaces aggregate failures with a retry control', () => {
+  const source = fs.readFileSync(VOCABULARY_TAB_PATH, 'utf8');
+
+  assert.match(source, /aggregatesError/);
+  assert.match(source, /onClick=\{refreshAggregates\}/);
+});
+
+test('useVocabulary loads exact card totals without holding up the vocabulary tables', () => {
+  const source = fs.readFileSync(VOCABULARY_HOOK_PATH, 'utf8');
+
   assert.match(
     source,
-    /const summary = useMemo\([\s\S]*buildVocabularySummary\(filteredWords, kanji\)[\s\S]*\[filteredWords, kanji\][\s\S]*\);/,
-  );
-  assert.match(
-    source,
-    /const knownWordCount = useMemo\(\(\) => \{[\s\S]*for \(const w of filteredWords\) \{[\s\S]*knownWords\.has\(w\.headword\)[\s\S]*\}\s*return count;\s*\}, \[filteredWords, knownWords\]\);/,
+    /Promise\.allSettled\(\[\s*client\.getVocabulary\(500\),\s*client\.getKanji\(200\),\s*client\.getKnownWords\(\),?\s*\]\)/,
   );
+  assert.match(source, /client\s*\.getVocabularySummary\(\)\s*\.then\(/);
+  assert.match(source, /client\s*\.getVocabularyCharts\(\)/);
 });