feat: objects table with M2M words/pictures/pairs

- objects: status enum, JSONB selections, notes, blocked_topic, auto-timestamps
- pairs placeholder table for future use
- Junction tables: object_words, object_pictures, object_pairs
- Full CRUD + link/unlink endpoints for all three relations
- README updated

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

src/routes/objects.js

@@ -0,0 +1,169 @@
+const router = require('express').Router();
+const { query } = require('../db');
+
+const STATUSES = ['draft', 'blocked', 'published'];
+
+const STATUS_TIMESTAMP = {
+  published: 'published_at',
+  blocked:   'blocked_at',
+};
+
+async function getWithRelations(id) {
+  const result = await query(
+    `SELECT o.*,
+      COALESCE(json_agg(DISTINCT ow.word_id)    FILTER (WHERE ow.word_id    IS NOT NULL), '[]') AS word_ids,
+      COALESCE(json_agg(DISTINCT op.picture_id) FILTER (WHERE op.picture_id IS NOT NULL), '[]') AS picture_ids,
+      COALESCE(json_agg(DISTINCT opr.pair_id)   FILTER (WHERE opr.pair_id   IS NOT NULL), '[]') AS pair_ids
+     FROM objects o
+     LEFT JOIN object_words    ow  ON ow.object_id  = o.id
+     LEFT JOIN object_pictures op  ON op.object_id  = o.id
+     LEFT JOIN object_pairs    opr ON opr.object_id = o.id
+     WHERE o.id = $1
+     GROUP BY o.id`,
+    [id]
+  );
+  return result.rows[0] || null;
+}
+
+// GET /api/objects
+router.get('/', async (req, res, next) => {
+  try {
+    const { status, limit = 50, offset = 0 } = req.query;
+    const params = [Math.min(parseInt(limit), 500), parseInt(offset)];
+    const where = status ? `WHERE o.status = $3` : '';
+    if (status) params.push(status);
+    const result = await query(
+      `SELECT o.*,
+        COALESCE(json_agg(DISTINCT ow.word_id)    FILTER (WHERE ow.word_id    IS NOT NULL), '[]') AS word_ids,
+        COALESCE(json_agg(DISTINCT op.picture_id) FILTER (WHERE op.picture_id IS NOT NULL), '[]') AS picture_ids,
+        COALESCE(json_agg(DISTINCT opr.pair_id)   FILTER (WHERE opr.pair_id   IS NOT NULL), '[]') AS pair_ids
+       FROM objects o
+       LEFT JOIN object_words    ow  ON ow.object_id  = o.id
+       LEFT JOIN object_pictures op  ON op.object_id  = o.id
+       LEFT JOIN object_pairs    opr ON opr.object_id = o.id
+       ${where}
+       GROUP BY o.id
+       ORDER BY o.created_at DESC
+       LIMIT $1 OFFSET $2`,
+      params
+    );
+    res.json(result.rows);
+  } catch (err) { next(err); }
+});
+
+// GET /api/objects/:id
+router.get('/:id', async (req, res, next) => {
+  try {
+    const row = await getWithRelations(req.params.id);
+    if (!row) return res.status(404).json({ error: 'Not found' });
+    res.json(row);
+  } catch (err) { next(err); }
+});
+
+// POST /api/objects
+router.post('/', async (req, res, next) => {
+  try {
+    const { selections, notes } = req.body;
+    const result = await query(
+      `INSERT INTO objects (selections, notes) VALUES ($1, $2) RETURNING *`,
+      [selections ? JSON.stringify(selections) : null, notes || null]
+    );
+    res.status(201).json({ ...result.rows[0], word_ids: [], picture_ids: [], pair_ids: [] });
+  } catch (err) { next(err); }
+});
+
+// PATCH /api/objects/:id
+router.patch('/:id', async (req, res, next) => {
+  try {
+    const allowed = ['status', 'selections', 'notes', 'blocked_topic', 'published_at', 'blocked_at'];
+    const fields = Object.keys(req.body).filter(k => allowed.includes(k));
+    if (!fields.length) return res.status(400).json({ error: 'No valid fields provided' });
+
+    if (req.body.status && !STATUSES.includes(req.body.status))
+      return res.status(400).json({ error: `status must be one of: ${STATUSES.join(', ')}` });
+
+    const tsField = STATUS_TIMESTAMP[req.body.status];
+    if (tsField && !req.body[tsField]) {
+      fields.push(tsField);
+      req.body[tsField] = new Date().toISOString();
+    }
+
+    const setClauses = fields.map((f, i) => `${f} = $${i + 1}`).join(', ');
+    const values = fields.map(f => f === 'selections' ? JSON.stringify(req.body[f]) : req.body[f]);
+    values.push(req.params.id);
+
+    const result = await query(
+      `UPDATE objects SET ${setClauses} WHERE id = $${fields.length + 1} RETURNING *`,
+      values
+    );
+    if (!result.rows.length) return res.status(404).json({ error: 'Not found' });
+    res.json(result.rows[0]);
+  } catch (err) { next(err); }
+});
+
+// DELETE /api/objects/:id
+router.delete('/:id', async (req, res, next) => {
+  try {
+    const result = await query('DELETE FROM objects WHERE id = $1 RETURNING id', [req.params.id]);
+    if (!result.rows.length) return res.status(404).json({ error: 'Not found' });
+    res.status(204).end();
+  } catch (err) { next(err); }
+});
+
+// --- Relations ---
+
+// POST   /api/objects/:id/words/:wordId
+router.post('/:id/words/:wordId', async (req, res, next) => {
+  try {
+    await query(`INSERT INTO object_words (object_id, word_id) VALUES ($1, $2) ON CONFLICT DO NOTHING`,
+      [req.params.id, req.params.wordId]);
+    res.status(204).end();
+  } catch (err) { next(err); }
+});
+
+// DELETE /api/objects/:id/words/:wordId
+router.delete('/:id/words/:wordId', async (req, res, next) => {
+  try {
+    await query(`DELETE FROM object_words WHERE object_id = $1 AND word_id = $2`,
+      [req.params.id, req.params.wordId]);
+    res.status(204).end();
+  } catch (err) { next(err); }
+});
+
+// POST   /api/objects/:id/pictures/:pictureId
+router.post('/:id/pictures/:pictureId', async (req, res, next) => {
+  try {
+    await query(`INSERT INTO object_pictures (object_id, picture_id) VALUES ($1, $2) ON CONFLICT DO NOTHING`,
+      [req.params.id, req.params.pictureId]);
+    res.status(204).end();
+  } catch (err) { next(err); }
+});
+
+// DELETE /api/objects/:id/pictures/:pictureId
+router.delete('/:id/pictures/:pictureId', async (req, res, next) => {
+  try {
+    await query(`DELETE FROM object_pictures WHERE object_id = $1 AND picture_id = $2`,
+      [req.params.id, req.params.pictureId]);
+    res.status(204).end();
+  } catch (err) { next(err); }
+});
+
+// POST   /api/objects/:id/pairs/:pairId
+router.post('/:id/pairs/:pairId', async (req, res, next) => {
+  try {
+    await query(`INSERT INTO object_pairs (object_id, pair_id) VALUES ($1, $2) ON CONFLICT DO NOTHING`,
+      [req.params.id, req.params.pairId]);
+    res.status(204).end();
+  } catch (err) { next(err); }
+});
+
+// DELETE /api/objects/:id/pairs/:pairId
+router.delete('/:id/pairs/:pairId', async (req, res, next) => {
+  try {
+    await query(`DELETE FROM object_pairs WHERE object_id = $1 AND pair_id = $2`,
+      [req.params.id, req.params.pairId]);
+    res.status(204).end();
+  } catch (err) { next(err); }
+});
+
+module.exports = router;