fix(ai,reader): robust sentence segmentation without abbreviation cutoffs & context-aware literary translation

- Implement robustSentenceSplit across reader.js and backend (miner.py, cefr.py) to prevent false cutoffs on honorifics (Mr., Mrs., Dr.), single-letter initials (John F. Kennedy), decimals, acronyms (U.S., U.K.), and abbreviations (No. 4, etc.)
- Upgrade translation prompt to professional literary Russian, eliminating literal word-for-word translation and preserving titles/honorifics
- Inject surrounding paragraph context into translation API to avoid out-of-context translations
- Inject offline dictionary hints into LLM prompt for accurate contextual word meaning
- Prefer qwen2.5:3b for higher translation fluency and fidelity
- Purge truncated cache entries from sentence_translations and restore Card 30 (briefcase) with authentic full sentence
- Bump Service Worker cache to notes-v6.0
- Add unit tests for robust sentence splitting, prompt formatting, and translation API

app/static/js/modules/api.js

@@ -114,13 +114,14 @@ export const api = {
             const resp = await fetch(`/api/detect-phrasal-verb?sentence=${encodeURIComponent(sentence)}&word=${encodeURIComponent(word)}`);
             return resp.ok ? await resp.json() : { detected: false, phrasal_verb: null };
         },
-        async translateSentence(sentence, targetWord = '') {
+        async translateSentence(sentence, targetWord = '', context = '') {
             const resp = await fetch('/api/translate-sentence', {
                 method: 'POST',
                 headers: { 'Content-Type': 'application/json' },
                 body: JSON.stringify({
                     sentence: sentence,
-                    target_word: targetWord
+                    target_word: targetWord,
+                    context: context
                 })
             });
             if (resp.ok) {

app/static/js/modules/reader.js

@@ -1104,40 +1104,51 @@ export function renderInteractiveSpans(container, text, contextText, knownWordsM
     });
 }
 
-const READER_HONORIFICS = [
-    'Mr.', 'Mrs.', 'Ms.', 'Dr.', 'Prof.', 'St.', 'vs.', 'etc.', 'e.g.', 'i.e.', 'Jr.', 'Sr.',
-    'Capt.', 'Col.', 'Gen.', 'Lt.', 'Sgt.', 'Rev.', 'Hon.'
-];
+export function robustSentenceSplit(text) {
+    if (!text) return [];
+    let s = text;
+
+    // Step 1: Protect decimal numbers (e.g. 3.14, 1.5)
+    s = s.replace(/(\d+)\.(\d+)/g, '$1§DOT§$2');
+
+    // Step 2: Protect acronyms with dots like U.S., U.K., e.g., i.e., a.m., p.m., Ph.D.
+    s = s.replace(/\b((?:[A-Za-z]\.){2,})/g, (m) => m.replace(/\./g, '§DOT§'));
+
+    // Step 3: Protect single-letter initials like 'John F. Kennedy', 'J. K. Rowling'
+    s = s.replace(/\b([A-Za-z])\.(?=\s+[A-Za-z0-9"“'‘«—])/g, '$1§DOT§');
+
+    // Step 4: Protect common honorifics, titles, and abbreviations
+    const abbrPattern = /\b(Mr|Mrs|Ms|Miss|Dr|Prof|Rev|Hon|Capt|Col|Gen|Lt|Cmdr|Sgt|Cpl|Pvt|Maj|Adm|Gov|Sen|Rep|Pres|Sec|Treas|Insp|Det|Supt|Messrs|Mmes|St|Mt|Ft|etc|vs|v|Jr|Sr|approx|app|apt|dept|univ|assn|assoc|bldg|co|corp|inc|ltd|est|misc|al|ibid|op|cit|ed|eds|trans|vol|vols|no|nos|sec|secs|ch|chs|fig|figs|p|pp|ave|blvd|rd|st|ct|ln|dr|hwy|jan|feb|mar|apr|jun|jul|aug|sep|sept|oct|nov|dec)\./gi;
+    s = s.replace(abbrPattern, '$1§DOT§');
+
+    // Step 5: Protect ellipsis (... or ....)
+    s = s.replace(/\.{2,}/g, (m) => '§ELLIPSIS§' + '§DOT§'.repeat(m.length));
+
+    // Step 6: Protect any period followed by lowercase letter (e.g. 'word. otherword')
+    s = s.replace(/\.([\'"”’»)]*\s+[a-zа-яё])/g, '§DOT§$1');
+
+    // Step 7: Split on sentence terminators [.!?] followed by whitespace and uppercase/number/quote/start of dialog
+    const marked = s.replace(/([.!?]['"”’»)]*)(\s+)(?=[A-Z0-9"“'‘«—]|$)/g, '$1§SEP§');
+
+    return marked.split('§SEP§')
+        .map(part => part.replace(/§DOT§/g, '.').replace(/§ELLIPSIS§/g, '').trim())
+        .filter(Boolean);
+}
 
 export function extractContextSentence(fullText, word) {
     if (!fullText) return '';
-    let protectedText = fullText;
-    for (const h of READER_HONORIFICS) {
-        if (protectedText.toLowerCase().includes(h.toLowerCase())) {
-            const safe = h.replace(/\./g, '§DOT§');
-            const reH = new RegExp(escapeRegex(h), 'gi');
-            protectedText = protectedText.replace(reH, safe);
-        }
-    }
-    // Protect decimal numbers (e.g. 3.14, 1.5)
-    protectedText = protectedText.replace(/(\d+)\.(\d+)/g, '$1§DOT§$2');
-
-    // Split sentences on terminal punctuation (.!?) followed by optional quotes/brackets and whitespace
-    const marked = protectedText.replace(/([.!?]['"”’»)]*)\s+/g, '$1§SEP§');
-    const rawSentences = marked.split('§SEP§');
-
+    const sentences = robustSentenceSplit(fullText);
     const cleanWord = (word || '').trim();
     if (cleanWord) {
         const escaped = escapeRegex(cleanWord);
         const wordRe = new RegExp(`(?:^|\\W)${escaped}(?:$|\\W)`, 'i');
-        for (const s of rawSentences) {
+        for (const s of sentences) {
             if (wordRe.test(s)) {
-                return s.replace(/§DOT§/g, '.').trim();
+                return s.replace(/\s+/g, ' ').trim();
             }
         }
     }
-
-    return fullText.slice(0, 160).trim();
+    return sentences.length > 0 ? sentences[0].replace(/\s+/g, ' ').trim() : fullText.slice(0, 160).trim();
 }
 
 // -----------------------------------------------------------------------
@@ -1176,7 +1187,7 @@ export function positionWordPopup(targetElement) {
     readerWordPopup.style.left = `${Math.round(left)}px`;
 }
 
-export async function openWordPopup(term, contextSentence, targetElement) {
+export async function openWordPopup(term, contextSentence, targetElement, paragraphContext = '') {
     const readerWordPopup = document.getElementById('reader-word-popup');
     const readerSettingsPanel = document.getElementById('reader-settings-panel');
     const popupTerm = document.getElementById('popup-term');
@@ -1202,6 +1213,7 @@ export async function openWordPopup(term, contextSentence, targetElement) {
     popupCurrentData = {
         term: cleanTerm,
         contextSentence: contextSentence,
+        paragraphContext: paragraphContext,
         targetElement: targetElement,
         existingCard: existingCard,
     };
@@ -1339,7 +1351,7 @@ export async function openWordPopup(term, contextSentence, targetElement) {
 
 export async function handleWordClick(word, paragraphText, targetElement) {
     const sentence = extractContextSentence(paragraphText, word);
-    openWordPopup(word, sentence, targetElement);
+    openWordPopup(word, sentence, targetElement, paragraphText);
 }
 
 function updatePopupPositionOnScroll() {
@@ -1965,7 +1977,7 @@ export function initReader() {
             if (popupContextMeaningWrap) popupContextMeaningWrap.classList.add('hidden');
 
             try {
-                const res = await api.lookup.translateSentence(ctxSentence, term);
+                const res = await api.lookup.translateSentence(ctxSentence, term, popupCurrentData.paragraphContext || '');
                 if (popupSentenceLoading) popupSentenceLoading.classList.add('hidden');
                 if (popupSentenceTranslationWrap) popupSentenceTranslationWrap.classList.remove('hidden');
 

app/static/sw.js

@@ -1,7 +1,7 @@
 // Service Worker for Notes English PWA (Stage 2)
 // Strategy: Cache-first for static assets, Network-first for API calls.
 
-const CACHE_NAME = 'notes-v5.9';
+const CACHE_NAME = 'notes-v6.0';
 const OFFLINE_URL = '/';
 
 const PRECACHE_URLS = [