Add custom word entry + language pair support for learning units

- New UnitBuilder component with language pair selector (DE⇄EN, ES, FR, etc.)
- Manual word entry form with auto-suggest from Kaikki dictionary (6M words)
- "No results" prompt to add multi-word terms (e.g. "schottisches Hochland")
- New backend endpoint GET /vocabulary/lookup-translation (any→any via EN hub)
- Updated POST /vocabulary/units: accepts custom_words + source_lang/target_lang
- Split unit endpoints into vocabulary/unit_api.py (500 LOC budget)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

studio-v2/app/vocabulary/page.tsx

@@ -5,11 +5,14 @@ import { useRouter } from 'next/navigation'
 import { useTheme } from '@/lib/ThemeContext'
 import { Sidebar } from '@/components/Sidebar'
 import { AudioButton } from '@/components/learn/AudioButton'
+import UnitBuilder, { type UnitWord } from './components/UnitBuilder'
 
 interface VocabWord {
   id: string
   english: string
   german: string
+  word?: string
+  lang?: string
   ipa_en: string
   ipa_de: string
   part_of_speech: string
@@ -20,11 +23,18 @@ interface VocabWord {
   image_url: string
   difficulty: number
   tags: string[]
+  translations?: Record<string, any>
 }
 
-/** Use Next.js API proxy to avoid mixed-content/CORS issues */
-function getApiBase() {
-  return ''  // Same-origin: /api/vocabulary/... proxied by Next.js
+function vocabToUnit(w: VocabWord, searchLang: string): UnitWord {
+  // Source = the word in the language we searched, Target = the translation
+  const src = w.word || w.english || ''
+  const tgt = searchLang === 'en'
+    ? (w.german || '')
+    : searchLang === 'de'
+      ? (w.english || '')
+      : (w.english || w.german || '')
+  return { id: w.id, source_text: src, target_text: tgt, pos: w.part_of_speech }
 }
 
 export default function VocabularyPage() {
@@ -39,11 +49,9 @@ export default function VocabularyPage() {
   const [diffFilter, setDiffFilter] = useState(0)
   const [searchLang, setSearchLang] = useState('en')
   const [topics, setTopics] = useState<{ topic: string; words: string[]; display_words?: string[]; word_count: number }[]>([])
-  const [showTopics, setShowTopics] = useState(false)
 
-  // Unit builder
-  const [selectedWords, setSelectedWords] = useState<VocabWord[]>([])
-  const [unitTitle, setUnitTitle] = useState('')
+  // Unit builder state (UnitWord format)
+  const [unitWords, setUnitWords] = useState<UnitWord[]>([])
   const [isCreating, setIsCreating] = useState(false)
 
   const glassCard = isDark
@@ -54,9 +62,8 @@ export default function VocabularyPage() {
     ? 'bg-white/10 border-white/20 text-white placeholder-white/40'
     : 'bg-white border-slate-200 text-slate-900 placeholder-slate-400'
 
-  // Load filters on mount
   useEffect(() => {
-    fetch(`${getApiBase()}/api/vocabulary/filters`)
+    fetch('/api/vocabulary/filters')
       .then(r => r.ok ? r.json() : null)
       .then(d => { if (d) setFilters(d) })
       .catch(() => {})
@@ -66,30 +73,28 @@ export default function VocabularyPage() {
   useEffect(() => {
     if (!query.trim() && !posFilter && !diffFilter) {
       setResults([])
+      setTopics([])
       return
     }
-
     const timer = setTimeout(async () => {
       setIsSearching(true)
       try {
         let url: string
         if (query.trim()) {
-          url = `${getApiBase()}/api/vocabulary/search?q=${encodeURIComponent(query)}&lang=${searchLang}&limit=30&source=kaikki`
+          url = `/api/vocabulary/search?q=${encodeURIComponent(query)}&lang=${searchLang}&limit=30&source=kaikki`
         } else {
           const params = new URLSearchParams({ limit: '30' })
           if (posFilter) params.set('pos', posFilter)
           if (diffFilter) params.set('difficulty', String(diffFilter))
-          url = `${getApiBase()}/api/vocabulary/browse?${params}`
+          url = `/api/vocabulary/browse?${params}`
         }
         const resp = await fetch(url)
         if (resp.ok) {
           const data = await resp.json()
           setResults(data.words || [])
         }
-
-        // Also search for matching topics
         if (query.trim()) {
-          const topicResp = await fetch(`${getApiBase()}/api/vocabulary/topics?q=${encodeURIComponent(query)}&lang=${searchLang}`)
+          const topicResp = await fetch(`/api/vocabulary/topics?q=${encodeURIComponent(query)}&lang=${searchLang}`)
           if (topicResp.ok) {
             const topicData = await topicResp.json()
             setTopics(topicData.topics || [])
@@ -101,28 +106,38 @@ export default function VocabularyPage() {
         setIsSearching(false)
       }
     }, 300)
-
     return () => clearTimeout(timer)
   }, [query, posFilter, diffFilter, searchLang])
 
   const toggleWord = useCallback((word: VocabWord) => {
-    setSelectedWords(prev => {
+    setUnitWords(prev => {
       const exists = prev.find(w => w.id === word.id)
       if (exists) return prev.filter(w => w.id !== word.id)
-      return [...prev, word]
+      return [...prev, vocabToUnit(word, searchLang)]
     })
-  }, [])
+  }, [searchLang])
 
-  const createUnit = useCallback(async () => {
-    if (!unitTitle.trim() || selectedWords.length === 0) return
+  const isSelected = (wordId: string) => unitWords.some(w => w.id === wordId)
+
+  const createUnit = useCallback(async (title: string, sourceLang: string, targetLang: string) => {
+    if (!title.trim() || unitWords.length === 0) return
     setIsCreating(true)
     try {
-      const resp = await fetch(`${getApiBase()}/api/vocabulary/units`, {
+      const dictWords = unitWords.filter(w => !w.is_custom)
+      const customWords = unitWords.filter(w => w.is_custom)
+
+      const resp = await fetch('/api/vocabulary/units', {
         method: 'POST',
         headers: { 'Content-Type': 'application/json' },
         body: JSON.stringify({
-          title: unitTitle,
-          word_ids: selectedWords.map(w => w.id),
+          title,
+          word_ids: dictWords.map(w => w.id),
+          custom_words: customWords.map(w => ({
+            source_text: w.source_text,
+            target_text: w.target_text,
+          })),
+          source_lang: sourceLang,
+          target_lang: targetLang,
         }),
       })
       if (resp.ok) {
@@ -134,9 +149,29 @@ export default function VocabularyPage() {
     } finally {
       setIsCreating(false)
     }
-  }, [unitTitle, selectedWords, router])
+  }, [unitWords, router])
 
-  const isSelected = (wordId: string) => selectedWords.some(w => w.id === wordId)
+  const addTopicWords = useCallback(async (topic: { words: string[] }, showOnly: boolean) => {
+    setIsSearching(true)
+    const topicWords: VocabWord[] = []
+    for (const w of topic.words) {
+      const r = await fetch(`/api/vocabulary/search?q=${encodeURIComponent(w)}&lang=en&limit=1&source=kaikki`)
+      if (r.ok) {
+        const d = await r.json()
+        if (d.words?.[0]) topicWords.push(d.words[0])
+      }
+    }
+    if (!showOnly) {
+      const newUnitWords = topicWords
+        .filter(tw => !unitWords.find(uw => uw.id === tw.id))
+        .map(tw => vocabToUnit(tw, 'en'))
+      setUnitWords(prev => [...prev, ...newUnitWords])
+    }
+    setResults(topicWords)
+    setIsSearching(false)
+  }, [unitWords])
+
+  const noSearchResults = !isSearching && results.length === 0 && !!query.trim() && topics.length === 0
 
   return (
     <div className={`min-h-screen flex relative overflow-hidden ${
@@ -157,7 +192,7 @@ export default function VocabularyPage() {
               <div>
                 <h1 className={`text-xl font-bold ${isDark ? 'text-white' : 'text-slate-900'}`}>Woerterbuch</h1>
                 <p className={`text-sm ${isDark ? 'text-white/60' : 'text-slate-500'}`}>
-                  {(filters as any).kaikki_total > 0 ? `${((filters as any).kaikki_total as number).toLocaleString()} Woerter in ${(filters as any).kaikki_languages} Sprachen` : filters.total_words > 0 ? `${filters.total_words.toLocaleString()} Woerter` : 'Woerter suchen und Lernunits erstellen'}
+                  {(filters as any).kaikki_total > 0 ? `${((filters as any).kaikki_total as number).toLocaleString()} Woerter in ${(filters as any).kaikki_languages} Sprachen` : 'Woerter suchen und Lernunits erstellen'}
                 </p>
               </div>
             </div>
@@ -184,18 +219,6 @@ export default function VocabularyPage() {
                   <option value="ar">AR</option>
                   <option value="uk">UK</option>
                   <option value="pl">PL</option>
-                  <option value="sv">SV</option>
-                  <option value="fi">FI</option>
-                  <option value="da">DA</option>
-                  <option value="ro">RO</option>
-                  <option value="el">EL</option>
-                  <option value="hu">HU</option>
-                  <option value="cs">CS</option>
-                  <option value="bg">BG</option>
-                  <option value="lv">LV</option>
-                  <option value="lt">LT</option>
-                  <option value="sk">SK</option>
-                  <option value="et">ET</option>
                 </select>
                 <input
                   type="text"
@@ -205,24 +228,9 @@ export default function VocabularyPage() {
                   className={`flex-1 px-4 py-3 rounded-xl border outline-none text-lg ${glassInput}`}
                   autoFocus
                 />
-                <select value={posFilter} onChange={e => setPosFilter(e.target.value)}
-                  className={`px-3 py-2 rounded-xl border text-sm ${glassInput}`}>
-                  <option value="">Alle Wortarten</option>
-                  {filters.parts_of_speech.map(p => <option key={p} value={p}>{p}</option>)}
-                </select>
-                <select value={diffFilter} onChange={e => setDiffFilter(Number(e.target.value))}
-                  className={`px-3 py-2 rounded-xl border text-sm ${glassInput}`}>
-                  <option value={0}>Alle Level</option>
-                  <option value={1}>A1</option>
-                  <option value={2}>A2</option>
-                  <option value={3}>B1</option>
-                  <option value={4}>B2</option>
-                  <option value={5}>C1</option>
-                </select>
               </div>
             </div>
 
-            {/* Results */}
             {isSearching && (
               <div className="flex justify-center py-8">
                 <div className={`w-6 h-6 border-2 ${isDark ? 'border-blue-400' : 'border-blue-600'} border-t-transparent rounded-full animate-spin`} />
@@ -236,7 +244,7 @@ export default function VocabularyPage() {
                   <div key={topic.topic} className={`${glassCard} rounded-xl p-3`}>
                     <div className="mb-2">
                       <span className={`text-sm font-semibold ${isDark ? 'text-cyan-300' : 'text-cyan-700'}`}>
-                        💡 {topic.topic} ({topic.word_count})
+                        {topic.topic} ({topic.word_count})
                       </span>
                     </div>
                     <div className="flex flex-wrap gap-1 mb-3">
@@ -248,44 +256,13 @@ export default function VocabularyPage() {
                       )}
                     </div>
                     <div className="flex gap-2">
-                      <button
-                        onClick={async () => {
-                          setIsSearching(true)
-                          const topicWords: VocabWord[] = []
-                          for (const w of topic.words) {
-                            const r = await fetch(`${getApiBase()}/api/vocabulary/search?q=${encodeURIComponent(w)}&lang=en&limit=1&source=kaikki`)
-                            if (r.ok) {
-                              const d = await r.json()
-                              if (d.words?.[0]) topicWords.push(d.words[0])
-                            }
-                          }
-                          setResults(topicWords)
-                          setIsSearching(false)
-                        }}
-                        className={`flex-1 text-xs px-3 py-2 rounded-lg ${isDark ? 'bg-white/10 text-white/60 hover:bg-white/20' : 'bg-slate-100 text-slate-600 hover:bg-slate-200'}`}
-                      >
+                      <button onClick={() => addTopicWords(topic, true)}
+                        className={`flex-1 text-xs px-3 py-2 rounded-lg ${isDark ? 'bg-white/10 text-white/60 hover:bg-white/20' : 'bg-slate-100 text-slate-600 hover:bg-slate-200'}`}>
                         Anzeigen
                       </button>
-                      <button
-                        onClick={async () => {
-                          setIsSearching(true)
-                          const topicWords: VocabWord[] = []
-                          for (const w of topic.words) {
-                            const r = await fetch(`${getApiBase()}/api/vocabulary/search?q=${encodeURIComponent(w)}&lang=en&limit=1&source=kaikki`)
-                            if (r.ok) {
-                              const d = await r.json()
-                              if (d.words?.[0] && !selectedWords.find(s => s.id === d.words[0].id)) {
-                                topicWords.push(d.words[0])
-                              }
-                            }
-                          }
-                          setSelectedWords(prev => [...prev, ...topicWords])
-                          setResults(topicWords)
-                          setIsSearching(false)
-                        }}
-                        className={`flex-1 text-xs px-3 py-2 rounded-lg font-semibold ${isDark ? 'bg-cyan-500/30 text-cyan-200 hover:bg-cyan-500/40 border border-cyan-400/30' : 'bg-cyan-100 text-cyan-700 hover:bg-cyan-200 border border-cyan-300'}`}
-                      >
-                        ✚ Alle zur Unit
+                      <button onClick={() => addTopicWords(topic, false)}
+                        className={`flex-1 text-xs px-3 py-2 rounded-lg font-semibold ${isDark ? 'bg-cyan-500/30 text-cyan-200 hover:bg-cyan-500/40 border border-cyan-400/30' : 'bg-cyan-100 text-cyan-700 hover:bg-cyan-200 border border-cyan-300'}`}>
+                        + Alle zur Unit
                       </button>
                     </div>
                   </div>
@@ -293,12 +270,17 @@ export default function VocabularyPage() {
               </div>
             )}
 
-            {!isSearching && results.length === 0 && query.trim() && topics.length === 0 && (
+            {/* No results message */}
+            {noSearchResults && (
               <div className={`${glassCard} rounded-2xl p-8 text-center`}>
                 <p className={isDark ? 'text-white/50' : 'text-slate-500'}>Keine Ergebnisse fuer &quot;{query}&quot;</p>
+                <p className={`text-xs mt-2 ${isDark ? 'text-white/30' : 'text-slate-400'}`}>
+                  Du kannst das Wort rechts manuell hinzufuegen →
+                </p>
               </div>
             )}
 
+            {/* Result list */}
             <div className="space-y-2">
               {results.map(word => (
                 <div
@@ -310,7 +292,6 @@ export default function VocabularyPage() {
                   }`}
                   onClick={() => toggleWord(word)}
                 >
-                  {/* Image or emoji placeholder */}
                   <div className={`w-14 h-14 rounded-xl flex items-center justify-center text-2xl flex-shrink-0 ${isDark ? 'bg-white/5' : 'bg-slate-100'}`}>
                     {word.image_url ? (
                       <img src={word.image_url} alt={word.english} className="w-full h-full object-cover rounded-xl" />
@@ -318,33 +299,22 @@ export default function VocabularyPage() {
                       <span className="text-xl">📝</span>
                     )}
                   </div>
-
-                  {/* Word info */}
                   <div className="flex-1 min-w-0">
                     <div className="flex items-center gap-2">
-                      <span className={`font-bold text-lg ${isDark ? 'text-white' : 'text-slate-900'}`}>{word.english}</span>
+                      <span className={`font-bold text-lg ${isDark ? 'text-white' : 'text-slate-900'}`}>{word.word || word.english}</span>
                       {word.ipa_en && <span className={`text-sm ${isDark ? 'text-white/40' : 'text-slate-400'}`}>{word.ipa_en}</span>}
-                      <AudioButton text={word.english} lang="en" isDark={isDark} size="sm" />
+                      <AudioButton text={word.word || word.english} lang={word.lang || searchLang} isDark={isDark} size="sm" />
                     </div>
                     <div className="flex items-center gap-2">
-                      <span className={`${isDark ? 'text-white/70' : 'text-slate-600'}`}>{word.german}</span>
-                      <AudioButton text={word.german} lang="de" isDark={isDark} size="sm" />
-                    </div>
-                    <div className="flex items-center gap-2 mt-1">
-                      {word.part_of_speech && (
-                        <span className={`text-xs px-2 py-0.5 rounded-full ${isDark ? 'bg-purple-500/20 text-purple-300' : 'bg-purple-100 text-purple-700'}`}>
-                          {word.part_of_speech}
-                        </span>
-                      )}
-                      {word.syllables_en.length > 0 && (
-                        <span className={`text-xs ${isDark ? 'text-white/30' : 'text-slate-400'}`}>
-                          {word.syllables_en.join(' · ')}
-                        </span>
-                      )}
+                      <span className={`${isDark ? 'text-white/70' : 'text-slate-600'}`}>{word.german || word.english}</span>
+                      {word.german && <AudioButton text={word.german} lang="de" isDark={isDark} size="sm" />}
                     </div>
+                    {word.part_of_speech && (
+                      <span className={`text-xs px-2 py-0.5 rounded-full mt-1 inline-block ${isDark ? 'bg-purple-500/20 text-purple-300' : 'bg-purple-100 text-purple-700'}`}>
+                        {word.part_of_speech}
+                      </span>
+                    )}
                   </div>
-
-                  {/* Select indicator */}
                   <div className={`w-8 h-8 rounded-full flex items-center justify-center flex-shrink-0 transition-colors ${
                     isSelected(word.id)
                       ? 'bg-blue-500 text-white'
@@ -360,59 +330,17 @@ export default function VocabularyPage() {
           </div>
 
           {/* Right: Unit Builder */}
-          <div className="w-80 flex-shrink-0">
-            <div className={`${glassCard} rounded-2xl p-5 sticky top-6`}>
-              <h3 className={`text-lg font-semibold mb-3 ${isDark ? 'text-white' : 'text-slate-900'}`}>
-                Lernunit erstellen
-              </h3>
-
-              <input
-                type="text"
-                value={unitTitle}
-                onChange={e => setUnitTitle(e.target.value)}
-                placeholder="Titel (z.B. Unit 3 - Food)"
-                className={`w-full px-4 py-2.5 rounded-xl border outline-none text-sm mb-4 ${glassInput}`}
-              />
-
-              {selectedWords.length === 0 ? (
-                <p className={`text-sm text-center py-6 ${isDark ? 'text-white/40' : 'text-slate-400'}`}>
-                  Klicke auf Woerter um sie hinzuzufuegen
-                </p>
-              ) : (
-                <div className="space-y-1.5 max-h-80 overflow-y-auto mb-4">
-                  {selectedWords.map((w, i) => (
-                    <div key={w.id} className={`flex items-center justify-between px-3 py-2 rounded-lg ${isDark ? 'bg-white/5' : 'bg-slate-50'}`}>
-                      <div className="flex items-center gap-2 min-w-0">
-                        <span className={`text-xs w-5 text-center ${isDark ? 'text-white/30' : 'text-slate-400'}`}>{i+1}</span>
-                        <span className={`text-sm font-medium truncate ${isDark ? 'text-white' : 'text-slate-900'}`}>{w.english}</span>
-                        <span className={`text-xs truncate ${isDark ? 'text-white/40' : 'text-slate-400'}`}>{w.german}</span>
-                      </div>
-                      <button onClick={(e) => { e.stopPropagation(); toggleWord(w) }}
-                        className={`text-xs ${isDark ? 'text-red-400 hover:text-red-300' : 'text-red-500 hover:text-red-700'}`}>
-                        ✕
-                      </button>
-                    </div>
-                  ))}
-                </div>
-              )}
-
-              <div className={`text-xs mb-3 ${isDark ? 'text-white/40' : 'text-slate-400'}`}>
-                {selectedWords.length} Woerter ausgewaehlt
-              </div>
-
-              <button
-                onClick={createUnit}
-                disabled={isCreating || selectedWords.length === 0 || !unitTitle.trim()}
-                className={`w-full py-3 rounded-xl font-medium transition-all ${
-                  selectedWords.length > 0 && unitTitle.trim()
-                    ? 'bg-gradient-to-r from-blue-500 to-cyan-500 text-white hover:shadow-lg'
-                    : isDark ? 'bg-white/5 text-white/30' : 'bg-slate-100 text-slate-400'
-                }`}
-              >
-                {isCreating ? 'Wird erstellt...' : 'Lernunit starten'}
-              </button>
-            </div>
-          </div>
+          <UnitBuilder
+            isDark={isDark}
+            glassCard={glassCard}
+            glassInput={glassInput}
+            selectedWords={unitWords}
+            onWordsChange={setUnitWords}
+            onCreateUnit={createUnit}
+            isCreating={isCreating}
+            noSearchResults={noSearchResults}
+            searchQuery={query}
+          />
         </div>
       </div>
     </div>