Fix order import mapping and lot auto-switch robustness

db/README.md

@@ -6,6 +6,7 @@
 2. `db/migrations/0002_phase1_seed_methods.sql`
 3. `db/migrations/0003_phase1_inventory_forecast.sql`
 4. `db/migrations/0004_phase1_direct_sales.sql`
+5. `db/migrations/0005_phase1_auto_switch_fix.sql`
 
 ## Beispielausfuehrung
 
@@ -14,6 +15,7 @@ psql "$DATABASE_URL" -f db/migrations/0001_phase1_core.sql
 psql "$DATABASE_URL" -f db/migrations/0002_phase1_seed_methods.sql
 psql "$DATABASE_URL" -f db/migrations/0003_phase1_inventory_forecast.sql
 psql "$DATABASE_URL" -f db/migrations/0004_phase1_direct_sales.sql
+psql "$DATABASE_URL" -f db/migrations/0005_phase1_auto_switch_fix.sql
 ```
 
 ## Enthaltene Kernlogik in `0001`

db/migrations/0001_phase1_core.sql

@@ -665,7 +665,10 @@ BEGIN
   END IF;
 
   UPDATE stock_lot
-  SET status = 'current', updated_at = NOW()
+  SET
+    status = 'current',
+    lot_number = COALESCE(lot_number, format('AUTO-%s-%s', v_product_id, v_open_lot_id)),
+    updated_at = NOW()
   WHERE id = v_open_lot_id;
 
   INSERT INTO stock_lot (product_id, lot_number, status)

db/migrations/0005_phase1_auto_switch_fix.sql

@@ -0,0 +1,99 @@
+BEGIN;
+
+-- Fix lot auto-switch when current lot reaches zero:
+-- if the next open lot has no lot_number yet, assign one before switching to status=current.
+-- This avoids violating chk_stock_lot_number_required_for_non_open.
+
+CREATE OR REPLACE FUNCTION fn_auto_switch_lot_when_depleted()
+RETURNS TRIGGER
+LANGUAGE plpgsql
+AS $$
+DECLARE
+  v_product_id BIGINT;
+  v_open_lot_id BIGINT;
+  v_current_net NUMERIC;
+  v_event_key TEXT;
+BEGIN
+  -- only relevant when the updated lot is currently active
+  SELECT product_id
+  INTO v_product_id
+  FROM stock_lot
+  WHERE id = NEW.lot_id;
+
+  -- if lot is not current anymore, nothing to do
+  IF NOT EXISTS (
+    SELECT 1 FROM stock_lot WHERE id = NEW.lot_id AND status = 'current'
+  ) THEN
+    RETURN NEW;
+  END IF;
+
+  SELECT qty_net
+  INTO v_current_net
+  FROM v_stock_lot_balance
+  WHERE stock_lot_id = NEW.lot_id;
+
+  IF COALESCE(v_current_net, 0) > 0 THEN
+    RETURN NEW;
+  END IF;
+
+  -- lock all lots for this product to avoid race conditions
+  PERFORM 1
+  FROM stock_lot
+  WHERE product_id = v_product_id
+  FOR UPDATE;
+
+  -- confirm current lot is still current after lock
+  IF NOT EXISTS (
+    SELECT 1 FROM stock_lot WHERE id = NEW.lot_id AND status = 'current'
+  ) THEN
+    RETURN NEW;
+  END IF;
+
+  UPDATE stock_lot
+  SET status = 'closed', updated_at = NOW()
+  WHERE id = NEW.lot_id;
+
+  SELECT id
+  INTO v_open_lot_id
+  FROM stock_lot
+  WHERE product_id = v_product_id
+    AND status = 'open'
+  ORDER BY id
+  LIMIT 1
+  FOR UPDATE;
+
+  IF v_open_lot_id IS NULL THEN
+    RAISE EXCEPTION 'No open lot available for product % during auto switch', v_product_id;
+  END IF;
+
+  -- current/closed lots must have a lot_number due to chk_stock_lot_number_required_for_non_open.
+  UPDATE stock_lot
+  SET
+    status = 'current',
+    lot_number = COALESCE(lot_number, format('AUTO-%s-%s', v_product_id, v_open_lot_id)),
+    updated_at = NOW()
+  WHERE id = v_open_lot_id;
+
+  INSERT INTO stock_lot (product_id, lot_number, status)
+  VALUES (v_product_id, NULL, 'open');
+
+  v_event_key := format('lot.auto_switched:%s:%s', v_product_id, txid_current());
+
+  PERFORM fn_enqueue_event(
+    'lot.auto_switched',
+    v_event_key,
+    'stock_lot',
+    NEW.lot_id::TEXT,
+    jsonb_build_object(
+      'productId', v_product_id,
+      'closedLotId', NEW.lot_id,
+      'newCurrentLotId', v_open_lot_id,
+      'occurredAt', NOW()
+    )
+  );
+
+  RETURN NEW;
+END;
+$$;
+
+COMMIT;