migrate: backfill old {{uuid}} placeholders to new {{label.w/o:uuid}} format

Runs at startup (idempotent) — only touches rows that still contain bare
{{uuid}} placeholders. Looks up each UUID in words first, then objects,
and rewrites to {{label.w:uuid}} or {{label.o:uuid}} accordingly.

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

src/db-migrate.js

@@ -494,7 +494,93 @@ async function migrate() {
        AND bbox_x IS NULL
   `).catch(() => {});
 
+  // ── Migrate old {{uuid}} placeholders → new {{label.w:uuid}} / {{label.o:uuid}} ──
+  await migratePlaceholders();
+
   console.log('Migration complete');
 }
 
+// UUID regex — matches bare {{uuid}} but NOT already-migrated {{label.w:uuid}}
+const UUID_RE = /\{\{([0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12})\}\}/gi;
+
+async function migratePlaceholders() {
+  const textCols = {
+    questions:  ['sentence_de', 'sentence_en', 'sentence_sv'],
+    statements: [
+      'positive_sentence_de', 'positive_sentence_en', 'positive_sentence_sv',
+      'negative_sentence_de', 'negative_sentence_en', 'negative_sentence_sv',
+    ],
+  };
+
+  const uuidSet = new Set();
+  const affected = {};
+
+  for (const [table, cols] of Object.entries(textCols)) {
+    const whereClause = cols
+      .map(c => `${c} ~ '\\{\\{[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}\\}\\}'`)
+      .join(' OR ');
+    const { rows } = await query(`SELECT id, ${cols.join(', ')} FROM ${table} WHERE ${whereClause}`);
+    if (rows.length) {
+      affected[table] = rows;
+      rows.forEach(row => cols.forEach(col => {
+        for (const m of (row[col] || '').matchAll(UUID_RE)) uuidSet.add(m[1]);
+      }));
+    }
+  }
+
+  if (uuidSet.size === 0) return;
+
+  const uuids = [...uuidSet];
+  const labelMap = {};
+
+  // Words first
+  const { rows: wordRows } = await query(
+    `SELECT id, titel_de, titel_en FROM words WHERE id = ANY($1::uuid[])`, [uuids]
+  );
+  wordRows.forEach(w => { labelMap[w.id] = { label: w.titel_de || w.titel_en || 'Wort', type: 'w' }; });
+
+  // Remaining → objects
+  const missing = uuids.filter(id => !labelMap[id]);
+  if (missing.length) {
+    const { rows: objRows } = await query(
+      `SELECT o.id, w.titel_de, w.titel_en
+       FROM objects o
+       LEFT JOIN object_words ow ON ow.object_id = o.id
+       LEFT JOIN words w ON w.id = ow.word_id
+       WHERE o.id = ANY($1::uuid[])`, [missing]
+    );
+    const seen = new Set();
+    objRows.forEach(r => {
+      if (!seen.has(r.id)) {
+        seen.add(r.id);
+        labelMap[r.id] = { label: r.titel_de || r.titel_en || 'Objekt', type: 'o' };
+      }
+    });
+  }
+
+  // UPDATE affected rows
+  for (const [table, rows] of Object.entries(affected)) {
+    const cols = textCols[table];
+    for (const row of rows) {
+      const updates = {};
+      for (const col of cols) {
+        const text = row[col];
+        if (!text) continue;
+        const replaced = text.replace(UUID_RE, (_, uuid) => {
+          const info = labelMap[uuid];
+          return info ? `{{${info.label}.${info.type}:${uuid}}}` : `{{${uuid}}}`;
+        });
+        if (replaced !== text) updates[col] = replaced;
+      }
+      if (Object.keys(updates).length) {
+        const setClauses = Object.keys(updates).map((k, i) => `${k} = $${i + 2}`).join(', ');
+        await query(`UPDATE ${table} SET ${setClauses} WHERE id = $1`, [row.id, ...Object.values(updates)]);
+      }
+    }
+  }
+
+  const count = Object.values(affected).reduce((s, r) => s + r.length, 0);
+  if (count > 0) console.log(`Placeholder migration: updated ${count} rows`);
+}
+
 module.exports = migrate;