feat: new placeholder format {{label.w:id}} / {{label.o:id}}

- Labels are now embedded in sentence text — no DB lookup needed
- Objects fetch selections directly from objects table
- Pictures resolved via object_pairs join instead of sentence UUID scan
- Simpler placeholderMap: only type + selections for objects

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/routes/feed.js

@@ -1,6 +1,7 @@
 // GET /auth/feed?lang=sv&limit=20
-// Returns hydrated pairs for the learning feed (end-user JWT allowed).
+// Returns hydrated pairs for the learning feed.
-// {{uuid}} placeholders in sentences are resolved to word/object labels in all languages.
+// Placeholders in sentences: {{label.w:wordId}} or {{label.o:objectId}}
+// Pictures come from object_pairs → object_pictures → pictures.
 
 const router = require('express').Router();
 const jwt = require('jsonwebtoken');
@@ -18,11 +19,22 @@ function requireJwt(req, res, next) {
   }
 }
 
-// Extract all {{uuid}} placeholder values from a string
+// Parse {{label.w:uuid}} or {{label.o:uuid}} from a sentence string
-function extractUuids(text) {
+function extractPlaceholders(text) {
   if (!text) return [];
-  const matches = text.matchAll(/\{\{([0-9a-f-]{36})\}\}/g);
+  return [...text.matchAll(/\{\{([^.]+)\.(w|o):([0-9a-f-]{36})\}\}/g)]
-  return [...matches].map(m => m[1]);
+    .map(m => ({ label: m[1], type: m[2] === 'w' ? 'word' : 'object', id: m[3] }));
+}
+
+// Collect unique IDs of a given type from multiple placeholder arrays
+function collectIds(lists, filterType) {
+  const ids = new Set();
+  for (const list of lists) {
+    for (const p of list) {
+      if (!filterType || p.type === filterType) ids.add(p.id);
+    }
+  }
+  return [...ids];
 }
 
 router.get('/', requireJwt, async (req, res, next) => {
@@ -40,8 +52,8 @@ router.get('/', requireJwt, async (req, res, next) => {
       [limit]
     );
     if (!pairsRes.rows.length) return res.json([]);
-
+    const pairs   = pairsRes.rows;
-    const pairs = pairsRes.rows;
+    const pairIds = pairs.map(p => p.id);
 
     // 2. Collect IDs
     const questionIds  = [...new Set(pairs.map(p => p.question_id).filter(Boolean))];
@@ -54,8 +66,7 @@ router.get('/', requireJwt, async (req, res, next) => {
     const questionsMap = {};
     if (questionIds.length) {
       const r = await query(
-        `SELECT id, sentence_de, sentence_en, sentence_sv
+        `SELECT id, sentence_de, sentence_en, sentence_sv FROM questions WHERE id = ANY($1)`,
-           FROM questions WHERE id = ANY($1)`,
         [questionIds]
       );
       r.rows.forEach(q => { questionsMap[q.id] = q; });
@@ -73,8 +84,7 @@ router.get('/', requireJwt, async (req, res, next) => {
       r.rows.forEach(s => { statementsMap[s.id] = s; });
     }
 
-    // 5. Collect all {{uuid}} references from all sentences
+    // 5. Parse all placeholders → find object IDs that need selections
-    const allUuids = new Set();
     const allSentences = [
       ...Object.values(questionsMap).flatMap(q => [q.sentence_de, q.sentence_en, q.sentence_sv]),
       ...Object.values(statementsMap).flatMap(s => [
@@ -82,52 +92,34 @@ router.get('/', requireJwt, async (req, res, next) => {
         s.negative_sentence_de, s.negative_sentence_en, s.negative_sentence_sv,
       ]),
     ];
-    allSentences.forEach(s => extractUuids(s).forEach(u => allUuids.add(u)));
+    const allPlaceholderLists = allSentences.map(s => extractPlaceholders(s));
+    const objectIds = collectIds(allPlaceholderLists, 'object');
 
-    const uuidArr = [...allUuids];
+    // 6. Fetch selections for object placeholders
-
+    const selectionsMap = {}; // objectId → selections[]
-    // 6. Resolve UUIDs → words (direct) or via objects→words
+    if (objectIds.length) {
-    const placeholderMap = {}; // uuid → { de, en, sv }
+      const r = await query(
-    if (uuidArr.length) {
+        `SELECT id, selections FROM objects WHERE id = ANY($1)`,
-      // Direct word lookup
+        [objectIds]
-      const wordRes = await query(
-        `SELECT id, titel_de AS de, titel_en AS en, titel_sv AS sv FROM words WHERE id = ANY($1)`,
-        [uuidArr]
       );
-      wordRes.rows.forEach(w => {
+      r.rows.forEach(o => { selectionsMap[o.id] = o.selections || []; });
-        placeholderMap[w.id] = { de: w.de, en: w.en, sv: w.sv, type: 'word', bbox: null };
-      });
-
-      // Object lookup → get first linked word as label + selections polygon
-      const objUuids = uuidArr.filter(u => !placeholderMap[u]);
-      if (objUuids.length) {
-        const objRes = await query(
-          `SELECT ow.object_id AS id, w.titel_de AS de, w.titel_en AS en, w.titel_sv AS sv,
-                  o.selections
-             FROM object_words ow
-             JOIN words w ON w.id = ow.word_id
-             JOIN objects o ON o.id = ow.object_id
-            WHERE ow.object_id = ANY($1)`,
-          [objUuids]
-        );
-        // First word per object
-        const seen = new Set();
-        objRes.rows.forEach(r => {
-          if (!seen.has(r.id)) {
-            placeholderMap[r.id] = {
-              de: r.de, en: r.en, sv: r.sv,
-              type: 'object',
-              selections: r.selections || [],
-            };
-            seen.add(r.id);
-          }
-        });
-      }
-
     }
 
-    // 7. Fetch statement→word links (positive + negative)
+    // Build global placeholder map: id → { type, selections? }
-    const statWordMap = {}; // statementId → { positive: [], negative: [] }
+    // Labels are embedded in the sentence text — no lookup needed.
+    const placeholderMap = {};
+    for (const list of allPlaceholderLists) {
+      for (const p of list) {
+        if (!placeholderMap[p.id]) {
+          placeholderMap[p.id] = p.type === 'object'
+            ? { type: 'object', selections: selectionsMap[p.id] || [] }
+            : { type: 'word' };
+        }
+      }
+    }
+
+    // 7. Fetch positive + negative words for PairWordCard answer options
+    const statWordMap = {};
     if (statementIds.length) {
       const posRes = await query(
         `SELECT spw.statement_id, w.id, w.titel_de AS de, w.titel_en AS en, w.titel_sv AS sv
@@ -148,23 +140,37 @@ router.get('/', requireJwt, async (req, res, next) => {
       negRes.rows.forEach(r => { statWordMap[r.statement_id]?.negative.push({ id: r.id, de: r.de, en: r.en, sv: r.sv }); });
     }
 
-    // 8. Find pictures via object_pairs (direct pair → object link)
+    // 8. Fetch pictures via object_pairs → object_pictures → pictures (one per pair)
-    const pairIds = pairs.map(p => p.id);
+    const pictureMap = {}; // pairId → { url, blurhash }
-    const pairPictureMap = {}; // pairId → { url, blurhash }
     if (pairIds.length) {
       const picRes = await query(
-        `SELECT DISTINCT ON (op2.pair_id)
+        `SELECT DISTINCT ON (op.pair_id)
-                op2.pair_id, p.picture_link AS url, p.blurhash
+                op.pair_id, p.picture_link AS url, p.blurhash
-           FROM object_pairs op2
+           FROM object_pairs op
-           JOIN object_pictures op ON op.object_id = op2.object_id
+           JOIN object_pictures pic ON pic.object_id = op.object_id
-           JOIN pictures p ON p.id = op.picture_id
+           JOIN pictures p ON p.id = pic.picture_id
-          WHERE op2.pair_id = ANY($1)
+          WHERE op.pair_id = ANY($1)
-          ORDER BY op2.pair_id, p.created_at`,
+          ORDER BY op.pair_id, p.created_at`,
         [pairIds]
       );
-      picRes.rows.forEach(r => {
+      picRes.rows.forEach(r => { pictureMap[r.pair_id] = { url: r.url, blurhash: r.blurhash }; });
-        pairPictureMap[r.pair_id] = { url: r.url, blurhash: r.blurhash };
+    }
-      });
+
+    // 9. Build per-pair placeholder subset
+    function getPairPlaceholders(p) {
+      const sentences = [
+        questionsMap[p.question_id]?.sentence_de,
+        questionsMap[p.question_id]?.sentence_en,
+        questionsMap[p.question_id]?.sentence_sv,
+        statementsMap[p.positive_statement_id]?.positive_sentence_de,
+        statementsMap[p.positive_statement_id]?.positive_sentence_en,
+        statementsMap[p.positive_statement_id]?.positive_sentence_sv,
+        statementsMap[p.negative_statement_id]?.negative_sentence_de,
+        statementsMap[p.negative_statement_id]?.negative_sentence_en,
+        statementsMap[p.negative_statement_id]?.negative_sentence_sv,
+      ];
+      const ids = new Set(sentences.flatMap(s => extractPlaceholders(s).map(ph => ph.id)));
+      return Object.fromEntries([...ids].map(id => [id, placeholderMap[id] || null]));
     }
 
     function buildStatement(id) {
@@ -172,13 +178,13 @@ router.get('/', requireJwt, async (req, res, next) => {
       const s = statementsMap[id];
       return {
         id,
-        sentence_de: s.positive_sentence_de,
+        sentence_de:          s.positive_sentence_de,
-        sentence_en: s.positive_sentence_en,
+        sentence_en:          s.positive_sentence_en,
-        sentence_sv: s.positive_sentence_sv,
+        sentence_sv:          s.positive_sentence_sv,
         negative_sentence_de: s.negative_sentence_de,
         negative_sentence_en: s.negative_sentence_en,
         negative_sentence_sv: s.negative_sentence_sv,
-        answer: s.answer,
+        answer:         s.answer,
         positive_words: statWordMap[id]?.positive || [],
         negative_words: statWordMap[id]?.negative || [],
       };
@@ -190,29 +196,19 @@ router.get('/', requireJwt, async (req, res, next) => {
       return { id, sentence_de: q.sentence_de, sentence_en: q.sentence_en, sentence_sv: q.sentence_sv };
     }
 
-    // 9. Assemble
+    // 10. Assemble
-    const result = pairs.map(p => {
+    const result = pairs.map(p => ({
-      const allText = [
+      id:                  p.id,
-        questionsMap[p.question_id]?.sentence_de,
+      answer_type:         p.answer_type,
-        questionsMap[p.question_id]?.sentence_sv,
+      status:              p.status,
-        statementsMap[p.positive_statement_id]?.positive_sentence_de,
+      difficulty_level:    p.difficulty_level,
-        statementsMap[p.positive_statement_id]?.positive_sentence_sv,
+      lang,
-      ].join(' ');
+      question:            buildQuestion(p.question_id),
-      const pairUuids = extractUuids(allText);
+      positive_statement:  buildStatement(p.positive_statement_id),
-
+      negative_statement:  buildStatement(p.negative_statement_id),
-      return {
+      picture:             pictureMap[p.id] || null,
-        id: p.id,
+      placeholders:        getPairPlaceholders(p),
-        answer_type: p.answer_type,
+    }));
-        status: p.status,
-        difficulty_level: p.difficulty_level,
-        lang,
-        question:            buildQuestion(p.question_id),
-        positive_statement:  buildStatement(p.positive_statement_id),
-        negative_statement:  buildStatement(p.negative_statement_id),
-        picture:             pairPictureMap[p.id] || null,
-        placeholders:        Object.fromEntries(pairUuids.map(u => [u, placeholderMap[u] || null])),
-      };
-    });
 
     res.json(result);
   } catch (err) { next(err); }