feat: MercadoLibre mejoras - importar existentes, sync stock, sync ordenes

- meli_service.py: agrega get_user_items() para obtener publicaciones del vendedor
- marketplace_external_service.py:
  - import_existing_listings(): importa publicaciones existentes de ML a marketplace_listings
  - process_meli_sync_queue(): procesa cola de sincronizacion de stock a ML
  - Actualiza stock en ML via update_item(available_quantity)
- marketplace_external_bp.py:
  - POST /listings/import-existing - importa publicaciones existentes
  - POST /sync-stock - procesa cola de stock manualmente
  - POST /orders/sync - sincroniza ordenes manualmente
- inventory_engine.py: inserta en meli_sync_queue tras cada operacion de inventario
- migration v4.2: crea tabla meli_sync_queue

Prueba en tenant_refaccionaria_rached: 52 publicaciones importadas exitosamente

pos/blueprints/marketplace_external_bp.py

@@ -235,6 +235,26 @@ def create_listings():
         conn.close()
 
 
+@marketplace_ext_bp.route("/listings/import-existing", methods=["POST"])
+@require_auth()
+def import_existing_listings():
+    """Import all existing MercadoLibre listings for the connected seller."""
+    err = _require_meli_manage()
+    if err:
+        return err
+
+    conn = get_tenant_conn(g.tenant_id)
+    try:
+        result = meli_svc.import_existing_listings(conn)
+        return jsonify(result), 200
+    except ValueError as e:
+        return jsonify({"error": str(e)}), 400
+    except Exception as e:
+        return jsonify({"error": str(e)}), 500
+    finally:
+        conn.close()
+
+
 @marketplace_ext_bp.route("/inventory-check", methods=["POST"])
 @require_auth()
 def inventory_check():
@@ -254,6 +274,26 @@ def inventory_check():
         conn.close()
 
 
+@marketplace_ext_bp.route("/sync-stock", methods=["POST"])
+@require_auth()
+def sync_stock_to_meli():
+    """Process pending stock updates to MercadoLibre."""
+    err = _require_meli_manage()
+    if err:
+        return err
+
+    conn = get_tenant_conn(g.tenant_id)
+    try:
+        result = meli_svc.process_meli_sync_queue(conn)
+        return jsonify(result)
+    except ValueError as e:
+        return jsonify({"error": str(e)}), 400
+    except Exception as e:
+        return jsonify({"error": str(e)}), 500
+    finally:
+        conn.close()
+
+
 @marketplace_ext_bp.route("/categories/<category_id>/attributes", methods=["GET"])
 @require_auth()
 def category_attributes(category_id):
@@ -526,6 +566,26 @@ def answer_question(question_id):
 # ORDERS
 # ═══════════════════════════════════════════════════════════════════════════
 
+@marketplace_ext_bp.route("/orders/sync", methods=["POST"])
+@require_auth()
+def sync_orders():
+    """Manually trigger sync of MercadoLibre orders."""
+    err = _require_meli_manage()
+    if err:
+        return err
+
+    conn = get_tenant_conn(g.tenant_id)
+    try:
+        result = meli_svc.fetch_and_save_orders(conn)
+        return jsonify(result)
+    except ValueError as e:
+        return jsonify({"error": str(e)}), 400
+    except Exception as e:
+        return jsonify({"error": str(e)}), 500
+    finally:
+        conn.close()
+
+
 @marketplace_ext_bp.route("/orders", methods=["GET"])
 @require_auth()
 def list_orders():

pos/migrations/v4.2_meli_sync_queue.sql

@@ -0,0 +1,14 @@
+-- v4.2 — MercadoLibre sync queue for stock synchronization
+
+CREATE TABLE IF NOT EXISTS meli_sync_queue (
+    id SERIAL PRIMARY KEY,
+    inventory_id INTEGER NOT NULL REFERENCES inventory(id),
+    action VARCHAR(20) NOT NULL DEFAULT 'stock_update',
+    status VARCHAR(20) NOT NULL DEFAULT 'pending',
+    retry_count INTEGER DEFAULT 0,
+    error_message TEXT,
+    created_at TIMESTAMPTZ DEFAULT NOW(),
+    processed_at TIMESTAMPTZ
+);
+
+CREATE INDEX IF NOT EXISTS idx_meli_sync_pending ON meli_sync_queue(status, created_at) WHERE status = 'pending';

pos/services/inventory_engine.py

@@ -121,6 +121,18 @@ def record_operation(conn, inventory_id, branch_id, operation_type, quantity,
         notes
     ))
     op_id = cur.fetchone()[0]
+
+    # Queue ML stock sync if this product has an active ML listing
+    cur.execute("""
+        INSERT INTO meli_sync_queue (inventory_id, action, status)
+        SELECT %s, 'stock_update', 'pending'
+        WHERE EXISTS (
+            SELECT 1 FROM marketplace_listings
+            WHERE inventory_id = %s AND channel = 'mercadolibre' AND is_active = true
+        )
+        ON CONFLICT DO NOTHING
+    """, (inventory_id, inventory_id))
+
     cur.close()
     return op_id
 

pos/services/marketplace_external_service.py

@@ -1459,3 +1459,209 @@ def _create_sale_manual(tenant_conn, sale_data: dict, employee_id: int = None) -
     tenant_conn.commit()
     cur.close()
     return {"id": sale_id, **totals}
+
+
+# ═══════════════════════════════════════════════════════════════════════════
+# IMPORT EXISTING LISTINGS FROM ML
+# ═══════════════════════════════════════════════════════════════════════════
+
+def process_meli_sync_queue(tenant_conn, batch_size: int = 50) -> dict:
+    """Process pending meli_sync_queue items and update stock on MercadoLibre.
+
+    Called by a cronjob or manual trigger.
+    """
+    cfg = get_meli_config(tenant_conn)
+    svc = _get_meli_service(cfg)
+    if not svc:
+        raise ValueError("MercadoLibre not configured")
+
+    cur = tenant_conn.cursor()
+    cur.execute("""
+        SELECT id, inventory_id FROM meli_sync_queue
+        WHERE status = 'pending'
+        ORDER BY created_at ASC
+        LIMIT %s
+    """, (batch_size,))
+    items = cur.fetchall()
+
+    processed = 0
+    failed = 0
+
+    for queue_id, inventory_id in items:
+        # Get current stock
+        from services.inventory_engine import get_stock
+        stock = get_stock(tenant_conn, inventory_id, branch_id=None)
+
+        # Find the ML listing
+        cur.execute("""
+            SELECT external_item_id FROM marketplace_listings
+            WHERE inventory_id = %s AND channel = 'mercadolibre' AND is_active = true
+            LIMIT 1
+        """, (inventory_id,))
+        row = cur.fetchone()
+        if not row:
+            # No active listing, mark as done
+            cur.execute("""
+                UPDATE meli_sync_queue SET status = 'done', processed_at = NOW()
+                WHERE id = %s
+            """, (queue_id,))
+            tenant_conn.commit()
+            processed += 1
+            continue
+
+        external_item_id = row[0]
+
+        try:
+            svc.update_item(external_item_id, {"available_quantity": max(0, int(stock))})
+            cur.execute("""
+                UPDATE meli_sync_queue SET status = 'done', processed_at = NOW()
+                WHERE id = %s
+            """, (queue_id,))
+            tenant_conn.commit()
+            processed += 1
+        except MeliError as e:
+            tenant_conn.rollback()
+            err_msg = _extract_meli_error(e)
+            cur.execute("""
+                UPDATE meli_sync_queue
+                SET status = 'failed', retry_count = retry_count + 1,
+                    error_message = %s, processed_at = NOW()
+                WHERE id = %s
+            """, (err_msg[:500], queue_id))
+            tenant_conn.commit()
+            failed += 1
+        except Exception:
+            tenant_conn.rollback()
+            cur.execute("""
+                UPDATE meli_sync_queue
+                SET status = 'failed', retry_count = retry_count + 1,
+                    error_message = 'Unexpected error', processed_at = NOW()
+                WHERE id = %s
+            """, (queue_id,))
+            tenant_conn.commit()
+            failed += 1
+
+    cur.close()
+    return {"processed": processed, "failed": failed, "total": len(items)}
+
+
+def import_existing_listings(tenant_conn, page_limit: int = 50) -> dict:
+    """Import all existing MercadoLibre listings for the connected seller.
+
+    For each ML item, tries to match it to a local inventory product by:
+    1. seller_custom_field (if it contains a part_number)
+    2. inventory_sku_aliases.sku matching the ML item id
+    3. inventory.part_number matching the ML item id or title
+
+    Returns summary of imported / unmatched items.
+    """
+    cfg = get_meli_config(tenant_conn)
+    svc = _get_meli_service(cfg)
+    user_id = cfg.get("meli_user_id")
+    if not svc or not user_id:
+        raise ValueError("MercadoLibre not configured")
+
+    cur = tenant_conn.cursor()
+
+    # Build lookup maps for matching
+    cur.execute("SELECT id, part_number FROM inventory WHERE is_active = true")
+    inv_by_part = {r[1].strip().upper(): r[0] for r in cur.fetchall() if r[1]}
+
+    cur.execute("SELECT inventory_id, sku FROM inventory_sku_aliases WHERE is_active = true")
+    inv_by_sku = {r[1].strip().upper(): r[0] for r in cur.fetchall() if r[1]}
+
+    imported = 0
+    unmatched = 0
+    errors = 0
+    offset = 0
+
+    while True:
+        try:
+            resp = svc.get_user_items(str(user_id), limit=page_limit, offset=offset)
+        except MeliError as e:
+            cur.close()
+            raise ValueError(f"Failed to fetch items: {e}")
+
+        results = resp.get("results", [])
+        if not results:
+            break
+
+        for item_id in results:
+            try:
+                item = svc.get_item(item_id)
+            except MeliError:
+                errors += 1
+                continue
+
+            title = item.get("title", "")
+            price = item.get("price", 0)
+            status = item.get("status", "active")
+            permalink = item.get("permalink", "")
+            category_id = item.get("category_id", "")
+            custom_field = item.get("seller_custom_field", "") or ""
+
+            # Try to match to local inventory
+            inventory_id = None
+            cf_upper = custom_field.strip().upper()
+            if cf_upper and cf_upper in inv_by_part:
+                inventory_id = inv_by_part[cf_upper]
+            elif cf_upper and cf_upper in inv_by_sku:
+                inventory_id = inv_by_sku[cf_upper]
+            else:
+                item_id_upper = str(item_id).strip().upper()
+                if item_id_upper in inv_by_sku:
+                    inventory_id = inv_by_sku[item_id_upper]
+                elif item_id_upper in inv_by_part:
+                    inventory_id = inv_by_part[item_id_upper]
+
+            # Upsert listing
+            try:
+                cur.execute(
+                    """
+                    INSERT INTO marketplace_listings
+                        (inventory_id, channel, external_item_id, external_status,
+                         external_permalink, title, meli_category_id, publish_price,
+                         last_sync_at, sync_errors, is_active)
+                    VALUES (%s, 'mercadolibre', %s, %s, %s, %s, %s, %s, NOW(), NULL, true)
+                    ON CONFLICT (inventory_id, channel) WHERE is_active = true
+                    DO UPDATE SET
+                        external_item_id = EXCLUDED.external_item_id,
+                        external_status = EXCLUDED.external_status,
+                        external_permalink = EXCLUDED.external_permalink,
+                        title = EXCLUDED.title,
+                        meli_category_id = EXCLUDED.meli_category_id,
+                        publish_price = EXCLUDED.publish_price,
+                        last_sync_at = NOW(),
+                        sync_errors = NULL,
+                        is_active = true
+                    """,
+                    (
+                        inventory_id,
+                        str(item_id),
+                        status,
+                        permalink,
+                        title,
+                        category_id,
+                        price,
+                    ),
+                )
+                tenant_conn.commit()
+                if inventory_id:
+                    imported += 1
+                else:
+                    unmatched += 1
+            except Exception:
+                tenant_conn.rollback()
+                errors += 1
+
+        if len(results) < page_limit:
+            break
+        offset += page_limit
+
+    cur.close()
+    return {
+        "imported": imported,
+        "unmatched": unmatched,
+        "errors": errors,
+        "total_processed": imported + unmatched + errors,
+    }

pos/services/meli_service.py

@@ -158,6 +158,16 @@ class MeliService:
     def get_item(self, item_id: str) -> dict:
         return self._request("GET", f"/items/{item_id}")
 
+    def get_user_items(self, user_id: str, status: str = None, limit: int = 50, offset: int = 0) -> dict:
+        """Get all items published by a seller.
+
+        ML endpoint: GET /users/{user_id}/items/search
+        """
+        params = {"limit": limit, "offset": offset}
+        if status:
+            params["status"] = status
+        return self._request("GET", f"/users/{user_id}/items/search", params=params)
+
     def pause_item(self, item_id: str) -> dict:
         return self.update_item(item_id, {"status": "paused"})