third commit

lib/presentation/payment/providers/payment_controller.dart

@@ -74,11 +74,31 @@ class PaymentController extends StateNotifier<PaymentState> {
     return diff > 0 ? diff.asMoney : 0;
   }
 
+  /// Whether Complete Sale should be enabled.
+  ///
+  /// Cash is the strict case: the drawer cannot be reconciled and no change can
+  /// be calculated unless the cashier states what was handed over. Card, UPI
+  /// and wallet settle on the external terminal, so they need no amount here.
   bool get canConfirm {
+    if (_billTotal <= 0) return false;
+
+    // Staged splits already cover the bill.
+    if (balanceDue <= 0.01) return true;
+
     if (state.activeMethod.needsChange) {
-      return state.cashTendered >= balanceDue && balanceDue > 0;
+      return state.cashTendered >= balanceDue;
     }
-    return balanceDue > 0;
+    return true;
+  }
+
+  /// Why the button is disabled, for display next to it.
+  String? get blockedReason {
+    if (_billTotal <= 0) return 'Add at least one item before charging.';
+    if (canConfirm) return null;
+    if (state.activeMethod.needsChange) {
+      return 'Enter the cash received, or tap Exact.';
+    }
+    return null;
   }
 
   void selectMethod(PaymentMethod method) {
@@ -156,10 +176,10 @@ class PaymentController extends StateNotifier<PaymentState> {
 
       state = state.copyWith(isProcessing: false, result: result);
 
-      // Fire and forget — printing must never block the next sale.
-      final receipts = _ref.read(receiptServiceProvider);
-      unawaited(receipts.printDirect(result.transaction));
-      unawaited(receipts.openCashDrawer());
+      // No auto-print: with no roll printer attached this silently failed and
+      // looked like a bug. The receipt screen shows the bill on the terminal
+      // and offers Print, WhatsApp and Share explicitly.
+      unawaited(_ref.read(receiptServiceProvider).openCashDrawer());
       unawaited(_ref.read(soundServiceProvider).saleComplete());
 
       // Stock changed, so the grid must refresh; the new order changes the

lib/presentation/payment/screens/payment_screen.dart

@@ -125,7 +125,7 @@ class _PaymentScreenState extends ConsumerState<PaymentScreen> {
           );
         },
       ),
-      bottomNavigationBar: _bottomBar(cart.grandTotal, state, cart.isEmpty),
+      bottomNavigationBar: _bottomBar(controller, state, cart.grandTotal),
     );
   }
 
@@ -557,7 +557,15 @@ class _PaymentScreenState extends ConsumerState<PaymentScreen> {
   }
 
   // ------------------------------------------------------------ Bottom bar
-  Widget _bottomBar(double total, PaymentState state, bool cartEmpty) {
+  Widget _bottomBar(
+    PaymentController controller,
+    PaymentState state,
+    double total,
+  ) {
+    // A cash sale cannot complete until the cashier says what was handed over.
+    final canComplete = controller.canConfirm;
+    final reason = controller.blockedReason;
+
     return SafeArea(
       child: Container(
         padding: const EdgeInsets.fromLTRB(
@@ -599,13 +607,45 @@ class _PaymentScreenState extends ConsumerState<PaymentScreen> {
                   ],
                 ),
               ).animate().shake(duration: 300.ms, hz: 3),
+            if (reason != null && state.error == null)
+              Padding(
+                padding: const EdgeInsets.only(bottom: AppSpacing.sm),
+                child: Row(
+                  children: [
+                    const Icon(Icons.info_outline_rounded,
+                        size: 15, color: AppColors.textTertiary),
+                    const SizedBox(width: AppSpacing.sm),
+                    Expanded(
+                      child: Text(
+                        reason,
+                        style: const TextStyle(
+                          fontSize: 12.5,
+                          color: AppColors.textTertiary,
+                        ),
+                      ),
+                    ),
+                    if (state.activeMethod.needsChange)
+                      TextButton(
+                        onPressed: () => _setCash(controller.balanceDue),
+                        style: TextButton.styleFrom(
+                          minimumSize: const Size(0, 30),
+                          padding: const EdgeInsets.symmetric(
+                            horizontal: AppSpacing.md,
+                          ),
+                        ),
+                        child: const Text('Exact',
+                            style: TextStyle(fontSize: 12.5)),
+                      ),
+                  ],
+                ),
+              ),
             PrimaryButton(
               label: 'Complete Sale',
               icon: Icons.check_circle_outline_rounded,
               large: true,
               tone: ButtonTone.success,
               busy: state.isProcessing,
-              onPressed: cartEmpty ? null : _confirm,
+              onPressed: canComplete ? _confirm : null,
               trailing: Text(
                 Formatters.money(total),
                 style: AppTypography.money(19, color: Colors.white),