diff --git a/lib/features/gas_calculators/domain/blending/billed_fill.dart b/lib/features/gas_calculators/domain/blending/billed_fill.dart
index 3600869958..c076ace2e3 100644
--- a/lib/features/gas_calculators/domain/blending/billed_fill.dart
+++ b/lib/features/gas_calculators/domain/blending/billed_fill.dart
@@ -1,3 +1,5 @@
+import 'package:submersion/features/gas_calculators/domain/blending/blender_gas_role.dart';
+
 /// Enough for a busy Saturday without letting a synced blob grow forever.
 const int kMaxBilledFills = 100;
 
@@ -9,6 +11,8 @@ class BilledGasLine {
     required this.cost,
     this.freeGasLiters,
     this.cylinderLiters,
+    this.role,
+    this.startBar,
   });
 
   /// The gas as it was labelled when the fill was saved, e.g. "He" or
@@ -34,12 +38,30 @@ class BilledGasLine {
   /// recovered from settings that have since moved on.
   final double? cylinderLiters;
 
+  /// The fill gas a hand-entered gas fill was billed for (issue #2302).
+  /// Null on every line the blender computed: set only by "Add a line", so
+  /// editing that line can reopen the form on the same gas.
+  ///
+  /// [BilledFill.manualGasLine] tells a hand-entered fill apart by this field
+  /// alone, so a computed line must keep leaving it null.
+  final BlenderGasRole? role;
+
+  /// The pressure a hand-entered gas fill started from, in bar. The end
+  /// pressure is [startBar] + [addedBar] rather than a field of its own, so
+  /// the two can never disagree.
+  final double? startBar;
+
+  /// The pressure a hand-entered gas fill ended at, when its start is known.
+  double? get endBar => startBar == null ? null : startBar! + addedBar;
+
   Map<String, dynamic> toJson() => {
     'gas': gas,
     'addedBar': addedBar,
     if (cost != null) 'cost': cost,
     if (freeGasLiters != null) 'freeGasLiters': freeGasLiters,
     if (cylinderLiters != null) 'cylinderLiters': cylinderLiters,
+    if (role != null) 'role': role!.name,
+    if (startBar != null) 'startBar': startBar,
   };
 
   static BilledGasLine? fromJson(Object? json) {
@@ -50,49 +72,16 @@ class BilledGasLine {
     final cost = json['cost'];
     final liters = json['freeGasLiters'];
     final cylinderLiters = json['cylinderLiters'];
+    final role = json['role'];
+    final startBar = json['startBar'];
     return BilledGasLine(
       gas: gas,
       addedBar: bar.toDouble(),
       cost: cost is num ? cost.toDouble() : null,
       freeGasLiters: liters is num ? liters.toDouble() : null,
       cylinderLiters: cylinderLiters is num ? cylinderLiters.toDouble() : null,
-    );
-  }
-}
-
-/// The cylinder and mix behind a manually entered bill line.
-///
-/// Kept alongside the free-typed [BilledFill.total] rather than replacing it:
-/// the amount charged at a real counter is still whatever the blender typed,
-/// this only records what was actually filled so the line reads as more than
-/// a bare number (issue #1335).
-class BilledCustomMix {
-  const BilledCustomMix({
-    required this.cylinderLiters,
-    required this.o2,
-    required this.he,
-  });
-
-  final double cylinderLiters;
-  final double o2;
-  final double he;
-
-  Map<String, dynamic> toJson() => {
-    'cylinderLiters': cylinderLiters,
-    'o2': o2,
-    'he': he,
-  };
-
-  static BilledCustomMix? fromJson(Object? json) {
-    if (json is! Map) return null;
-    final liters = json['cylinderLiters'];
-    final o2 = json['o2'];
-    final he = json['he'];
-    if (liters is! num || o2 is! num || he is! num) return null;
-    return BilledCustomMix(
-      cylinderLiters: liters.toDouble(),
-      o2: o2.toDouble(),
-      he: he.toDouble(),
+      role: role is String ? BlenderGasRole.fromName(role) : null,
+      startBar: startBar is num ? startBar.toDouble() : null,
     );
   }
 }
@@ -110,7 +99,6 @@ class BilledFill {
     required this.label,
     required this.lines,
     required this.total,
-    this.customMix,
   });
 
   final String id;
@@ -119,19 +107,20 @@ class BilledFill {
   /// line such as "O2 analyser cell".
   final String label;
 
-  /// Empty for a manually added line: there is no fill behind it to itemise.
+  /// Empty for a free-amount line: there is no fill behind it to itemise.
   final List<BilledGasLine> lines;
 
   /// Null when the fill was saved before every gas had a price.
   final double? total;
 
-  /// The cylinder and mix entered for a manual line, when the blender chose
-  /// to record one. Always null for a computed fill: [lines] already
-  /// itemises it.
-  final BilledCustomMix? customMix;
-
+  /// A free-amount line, typed in by hand with nothing to itemise.
   bool get isManual => lines.isEmpty;
 
+  /// The single gas line of a gas fill entered through "Add a line" (issue
+  /// #2302), or null for a free-amount line or a fill the blender computed.
+  BilledGasLine? get manualGasLine =>
+      lines.length == 1 && lines.single.role != null ? lines.single : null;
+
   /// [clearTotal] is how an amount gets removed. Null is meaningful here: it
   /// marks a line as not yet priced, which is what makes the grand total
   /// report itself incomplete, and `total ?? this.total` could not express it,
@@ -141,21 +130,19 @@ class BilledFill {
   /// gives up compile-time typing: `copyWith(total: 40)` then compiles and
   /// throws at run time on the int literal.
   ///
-  /// [clearCustomMix] follows the same shape: re-editing a manual line to
-  /// remove its mix has to be expressible, and `customMix ?? this.customMix`
-  /// could not tell "unchanged" from "cleared" any more than `total` could.
+  /// [lines] is replaced only when given: a hand-entered line can switch
+  /// between a free amount and a gas fill when it is edited (issue #2302),
+  /// while a computed fill keeps the itemisation it was saved with.
   BilledFill copyWith({
     String? label,
+    List<BilledGasLine>? lines,
     double? total,
     bool clearTotal = false,
-    BilledCustomMix? customMix,
-    bool clearCustomMix = false,
   }) => BilledFill(
     id: id,
     label: label ?? this.label,
-    lines: lines,
+    lines: lines ?? this.lines,
     total: clearTotal ? null : (total ?? this.total),
-    customMix: clearCustomMix ? null : (customMix ?? this.customMix),
   );
 
   Map<String, dynamic> toJson() => {
@@ -163,7 +150,6 @@ class BilledFill {
     'label': label,
     'lines': lines.map((l) => l.toJson()).toList(),
     if (total != null) 'total': total,
-    if (customMix != null) 'customMix': customMix!.toJson(),
   };
 
   static BilledFill? fromJson(Object? json) {
@@ -183,7 +169,6 @@ class BilledFill {
                 .toList()
           : const [],
       total: total is num ? total.toDouble() : null,
-      customMix: BilledCustomMix.fromJson(json['customMix']),
     );
   }
 }
diff --git a/lib/features/gas_calculators/domain/blending/blend_billing.dart b/lib/features/gas_calculators/domain/blending/blend_billing.dart
index d5f4c2a887..51bdb38efd 100644
--- a/lib/features/gas_calculators/domain/blending/blend_billing.dart
+++ b/lib/features/gas_calculators/domain/blending/blend_billing.dart
@@ -110,3 +110,59 @@ BillingResult computeBlendCost({
 
   return BillingResult(lines: lines, total: complete ? total : null);
 }
+
+/// What a single hand-entered gas fill costs.
+class ManualGasFillCost {
+  const ManualGasFillCost({
+    required this.addedBar,
+    required this.freeGasLiters,
+    required this.cost,
+  });
+
+  /// End pressure minus start pressure.
+  final double addedBar;
+
+  /// Free gas at the surface, in litres: the same ideal
+  /// `water volume x bar delivered` [computeBlendCost] charges for.
+  final double freeGasLiters;
+
+  final double cost;
+}
+
+/// Price one gas filled by hand into a cylinder of [waterLiters] water
+/// capacity, from [startBar] up to [endBar], at [pricePer100] per 100 litres
+/// of free gas (issue #2302).
+///
+/// A gas with no price is charged at 0 rather than left unpriced: the line
+/// was entered by hand for a gas the blender chose, and the amount is shown
+/// before it is saved, so a zero is visible where a silent gap in the total
+/// would not be.
+///
+/// Null when the input cannot describe a fill: no cylinder, a negative start
+/// pressure, an end pressure not above the start, or a non-finite value.
+ManualGasFillCost? manualGasFillCost({
+  required double waterLiters,
+  required double startBar,
+  required double endBar,
+  required double? pricePer100,
+}) {
+  if (!waterLiters.isFinite || !startBar.isFinite || !endBar.isFinite) {
+    return null;
+  }
+  // A corrupt tariff is not an unset one: charging it as 0 would pass a
+  // broken price off as a deliberate free fill.
+  if (pricePer100 != null && !pricePer100.isFinite) return null;
+  if (waterLiters <= 0 || startBar < 0 || endBar <= startBar) return null;
+  final addedBar = endBar - startBar;
+  final liters = waterLiters * addedBar;
+  final price = pricePer100 ?? 0;
+  final cost = liters / 100 * price;
+  // Finite inputs can still multiply out to infinity, which a saved bill
+  // could not encode as JSON.
+  if (!liters.isFinite || !cost.isFinite) return null;
+  return ManualGasFillCost(
+    addedBar: addedBar,
+    freeGasLiters: liters,
+    cost: cost,
+  );
+}
diff --git a/lib/features/gas_calculators/presentation/pages/blender_invoice_archive_detail_page.dart b/lib/features/gas_calculators/presentation/pages/blender_invoice_archive_detail_page.dart
index db8490a48e..3483a928d7 100644
--- a/lib/features/gas_calculators/presentation/pages/blender_invoice_archive_detail_page.dart
+++ b/lib/features/gas_calculators/presentation/pages/blender_invoice_archive_detail_page.dart
@@ -3,8 +3,6 @@ import 'package:flutter/material.dart';
 import 'package:submersion/core/providers/provider.dart';
 import 'package:submersion/core/utils/currency.dart';
 import 'package:submersion/core/utils/unit_formatter.dart';
-import 'package:submersion/features/dive_log/domain/entities/dive.dart'
-    show GasMix;
 import 'package:submersion/features/gas_calculators/domain/blending/billed_fill.dart';
 import 'package:submersion/features/gas_calculators/presentation/providers/gas_blender_providers.dart';
 import 'package:submersion/features/gas_calculators/presentation/widgets/blender/blender_archived_invoice_tile.dart';
@@ -171,21 +169,6 @@ class BlenderInvoiceArchiveDetailPage extends ConsumerWidget {
               units: units,
               decimals: decimals,
             ),
-          // A manual (lump-sum) fill has no gas lines, only the mix and
-          // cylinder it was filled to -- the running invoice shows that same
-          // row after its gas lines, and the archive lost it entirely
-          // (Copilot review, issue #1876 follow-up).
-          if (fill.customMix case final mix?)
-            Padding(
-              padding: const EdgeInsets.only(left: 16, top: 2),
-              child: Text(
-                '${units.formatVolume(mix.cylinderLiters)} · '
-                '${formatPreciseMix(context, GasMix(o2: mix.o2, he: mix.he))}',
-                style: theme.textTheme.bodySmall?.copyWith(
-                  color: theme.colorScheme.onSurfaceVariant,
-                ),
-              ),
-            ),
         ],
       ),
     );
diff --git a/lib/features/gas_calculators/presentation/widgets/blender/blender_invoice_card.dart b/lib/features/gas_calculators/presentation/widgets/blender/blender_invoice_card.dart
index ecf85a0c18..aa12b935fb 100644
--- a/lib/features/gas_calculators/presentation/widgets/blender/blender_invoice_card.dart
+++ b/lib/features/gas_calculators/presentation/widgets/blender/blender_invoice_card.dart
@@ -2,7 +2,6 @@ import 'dart:ui' as ui show ImageByteFormat;
 
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
-import 'package:flutter/services.dart';
 import 'package:go_router/go_router.dart';
 import 'package:submersion/core/providers/provider.dart';
 import 'package:submersion/core/services/export/export_service.dart';
@@ -10,22 +9,19 @@ import 'package:submersion/core/utils/currency.dart';
 import 'package:submersion/core/utils/number_input.dart';
 import 'package:submersion/core/utils/unit_formatter.dart';
 import 'package:submersion/features/divers/presentation/providers/diver_providers.dart';
-import 'package:submersion/features/dive_log/domain/entities/dive.dart'
-    show GasMix;
 import 'package:submersion/features/gas_calculators/domain/blending/billed_fill.dart';
 import 'package:submersion/features/gas_calculators/domain/blending/blender_gas_role.dart';
-import 'package:submersion/features/gas_calculators/domain/blending/blender_preferences.dart';
 import 'package:submersion/features/gas_calculators/domain/blending/flush_fee.dart';
 import 'package:submersion/features/gas_calculators/presentation/gas_calculator_tools.dart';
 import 'package:submersion/features/gas_calculators/presentation/providers/gas_blender_providers.dart';
 import 'package:submersion/features/gas_calculators/presentation/widgets/blender/blender_billed_line_row.dart';
 import 'package:submersion/features/gas_calculators/presentation/widgets/blender/blender_formatting.dart';
 import 'package:submersion/features/gas_calculators/presentation/widgets/blender/blender_invoice_export_sheet.dart';
+import 'package:submersion/features/gas_calculators/presentation/widgets/blender/blender_line_edit_sheet.dart';
 import 'package:submersion/features/gas_calculators/presentation/widgets/blender/blender_section_title.dart';
 import 'package:submersion/features/gas_calculators/presentation/widgets/blender/blender_table_style.dart';
 import 'package:submersion/features/gas_calculators/presentation/widgets/blender/blender_volume_conversion.dart';
 import 'package:submersion/features/settings/presentation/providers/settings_providers.dart';
-import 'package:submersion/features/tank_presets/presentation/providers/tank_preset_providers.dart';
 import 'package:submersion/l10n/l10n_extension.dart';
 import 'package:submersion/shared/widgets/app_date_picker.dart';
 
@@ -779,17 +775,6 @@ class _BlenderInvoiceCardState extends ConsumerState<BlenderInvoiceCard> {
               units: units,
               decimals: decimals,
             ),
-          if (fill.customMix case final mix?)
-            Padding(
-              padding: const EdgeInsets.only(left: 16, top: 2),
-              child: Text(
-                '${units.formatVolume(mix.cylinderLiters)} · '
-                '${formatPreciseMix(context, GasMix(o2: mix.o2, he: mix.he))}',
-                style: theme.textTheme.bodySmall?.copyWith(
-                  color: theme.colorScheme.onSurfaceVariant,
-                ),
-              ),
-            ),
         ],
       ),
     );
@@ -840,16 +825,18 @@ class _BlenderInvoiceCardState extends ConsumerState<BlenderInvoiceCard> {
     saveBlenderPreferences(ref);
   }
 
-  /// Edit an existing line, or add a manual one when [fill] is null.
+  /// Edit an existing line, or add a hand-entered one when [fill] is null.
   ///
-  /// The amount stays editable on computed fills too: rounding and the
-  /// occasional discount happen at a real counter, and re-blending the
-  /// cylinder to change what it costs would be absurd.
+  /// The amount stays editable on computed fills and free-amount lines:
+  /// rounding and the occasional discount happen at a real counter, and
+  /// re-blending the cylinder to change what it costs would be absurd. A gas
+  /// fill entered here is the exception, priced from what was filled
+  /// (issue #2302).
   Future<void> _editLine(BilledFill? fill) async {
-    final edited = await showModalBottomSheet<_LineEdit>(
+    final edited = await showModalBottomSheet<BlenderLineEdit>(
       context: context,
       isScrollControlled: true,
-      builder: (context) => _LineEditSheet(fill: fill),
+      builder: (context) => BlenderLineEditSheet(fill: fill),
     );
     if (edited == null) return;
 
@@ -860,9 +847,8 @@ class _BlenderInvoiceCardState extends ConsumerState<BlenderInvoiceCard> {
         BilledFill(
           id: DateTime.now().microsecondsSinceEpoch.toString(),
           label: edited.label,
-          lines: const [],
+          lines: edited.lines ?? const [],
           total: edited.amount,
-          customMix: edited.customMix,
         ),
       );
     } else {
@@ -871,10 +857,9 @@ class _BlenderInvoiceCardState extends ConsumerState<BlenderInvoiceCard> {
           if (f.id == fill.id)
             f.copyWith(
               label: edited.label,
+              lines: edited.lines,
               total: edited.amount,
               clearTotal: edited.amount == null,
-              customMix: edited.customMix,
-              clearCustomMix: edited.customMix == null,
             )
           else
             f,
@@ -940,312 +925,3 @@ class _BlenderInvoiceCardState extends ConsumerState<BlenderInvoiceCard> {
 
 /// The two actions offered by a fill line's overflow menu.
 enum _FillLineAction { edit, delete }
-
-/// What the edit sheet hands back.
-class _LineEdit {
-  const _LineEdit({required this.label, required this.amount, this.customMix});
-  final String label;
-  final double? amount;
-  final BilledCustomMix? customMix;
-}
-
-/// Owns its own controllers, and disposes them in its own State.
-///
-/// Creating them in the caller and disposing on the sheet's future looks
-/// equivalent and is not: the future completes when the route is popped, while
-/// the exit transition keeps rebuilding these fields for several more frames
-/// against a controller that is already gone.
-///
-/// A scrollable, keyboard-aware bottom sheet rather than the fixed-size
-/// `AlertDialog` this replaced: a cylinder row and an O2/He row roughly
-/// double the field count, and a taller fixed dialog risks overflow once the
-/// keyboard is up on the narrowest phone the app supports (issue #1335).
-class _LineEditSheet extends ConsumerStatefulWidget {
-  const _LineEditSheet({required this.fill});
-
-  final BilledFill? fill;
-
-  @override
-  ConsumerState<_LineEditSheet> createState() => _LineEditSheetState();
-}
-
-class _LineEditSheetState extends ConsumerState<_LineEditSheet> {
-  late final TextEditingController _label;
-  late final TextEditingController _amount;
-  late final TextEditingController _cylinder;
-  late final TextEditingController _o2;
-  late final TextEditingController _he;
-
-  /// Only a new line or one that is still a manual/custom-mix entry offers
-  /// the cylinder and mix fields. A computed fill's gases are already
-  /// itemised in [BilledFill.lines]; editing them here would let the label
-  /// and the itemisation disagree.
-  bool get _showMix => widget.fill == null || widget.fill!.isManual;
-
-  String? _error;
-
-  @override
-  void initState() {
-    super.initState();
-    final fill = widget.fill;
-    final settings = ref.read(settingsProvider);
-    _label = TextEditingController(text: fill?.label ?? '');
-    _amount = TextEditingController(
-      text: fill?.total == null ? '' : formatRoundedForInput(fill!.total!, 2),
-    );
-    final mix = fill?.customMix;
-    final double cylinderLiters =
-        mix?.cylinderLiters ?? ref.read(blenderCylinderLitersProvider);
-    _cylinder = TextEditingController(
-      text: formatRoundedForInput(
-        litersToDisplayVolume(cylinderLiters, settings),
-        2,
-      ),
-    );
-    _o2 = TextEditingController(text: formatRoundedForInput(mix?.o2 ?? 21, 1));
-    _he = TextEditingController(text: formatRoundedForInput(mix?.he ?? 0, 1));
-  }
-
-  @override
-  void dispose() {
-    _label.dispose();
-    _amount.dispose();
-    _cylinder.dispose();
-    _o2.dispose();
-    _he.dispose();
-    super.dispose();
-  }
-
-  void _submit() {
-    final label = _label.text.trim();
-    final amount = parseUserDecimal(_amount.text);
-    BilledCustomMix? customMix;
-    if (_showMix) {
-      final settings = ref.read(settingsProvider);
-      final liters = parseUserDecimal(_cylinder.text);
-      final o2 = parseUserDecimal(_o2.text);
-      final he = parseUserDecimal(_he.text);
-      if (liters != null && o2 != null && he != null) {
-        if (!MixTemplate(o2: o2, he: he).isValid) {
-          setState(
-            () => _error = context.l10n.gasCalculators_blender_error_invalidMix,
-          );
-          return;
-        }
-        customMix = BilledCustomMix(
-          cylinderLiters: displayVolumeToLiters(liters, settings),
-          o2: o2,
-          he: he,
-        );
-      }
-    }
-    final effectiveLabel = label.isNotEmpty
-        ? label
-        : customMix != null
-        ? formatPreciseMix(context, GasMix(o2: customMix.o2, he: customMix.he))
-        : '';
-    // Nothing to name the line with. Said out loud rather than returned on
-    // quietly: a Save that does nothing and explains nothing reads as a
-    // broken button (PR #1359 review), the same reasoning MixTemplateManager
-    // applies to a half-typed mix.
-    if (effectiveLabel.isEmpty) {
-      setState(
-        () => _error = context.l10n.gasCalculators_blender_lineNeedsDescription,
-      );
-      return;
-    }
-    Navigator.of(context).pop(
-      _LineEdit(label: effectiveLabel, amount: amount, customMix: customMix),
-    );
-  }
-
-  @override
-  Widget build(BuildContext context) {
-    final fill = widget.fill;
-    final settings = ref.watch(settingsProvider);
-    final units = UnitFormatter(settings);
-    return Padding(
-      padding: EdgeInsets.only(
-        left: 16,
-        right: 16,
-        top: 16,
-        bottom: MediaQuery.of(context).viewInsets.bottom + 16,
-      ),
-      child: SingleChildScrollView(
-        child: Column(
-          mainAxisSize: MainAxisSize.min,
-          crossAxisAlignment: CrossAxisAlignment.stretch,
-          children: [
-            Text(
-              fill == null
-                  ? context.l10n.gasCalculators_blender_addManualLine
-                  : context.l10n.gasCalculators_blender_editLine(fill.label),
-              style: Theme.of(context).textTheme.titleMedium,
-            ),
-            const SizedBox(height: 16),
-            TextField(
-              key: const Key('blender-line-description'),
-              controller: _label,
-              autofocus: true,
-              decoration: InputDecoration(
-                labelText: context.l10n.gasCalculators_blender_lineDescription,
-                isDense: true,
-                border: const OutlineInputBorder(),
-              ),
-            ),
-            const SizedBox(height: 12),
-            if (_showMix) ...[
-              _cylinderRow(context, settings, units),
-              const SizedBox(height: 12),
-              Row(
-                children: [
-                  Expanded(
-                    child: _numberField(
-                      context,
-                      _o2,
-                      context.l10n.gasCalculators_blender_o2,
-                    ),
-                  ),
-                  const SizedBox(width: 8),
-                  Expanded(
-                    child: _numberField(
-                      context,
-                      _he,
-                      context.l10n.gasCalculators_blender_he,
-                    ),
-                  ),
-                ],
-              ),
-              const SizedBox(height: 12),
-            ],
-            TextField(
-              key: const Key('blender-line-amount'),
-              controller: _amount,
-              keyboardType: const TextInputType.numberWithOptions(
-                decimal: true,
-              ),
-              onSubmitted: (_) => _submit(),
-              decoration: InputDecoration(
-                labelText: context.l10n.gasCalculators_blender_lineAmount,
-                isDense: true,
-                border: const OutlineInputBorder(),
-              ),
-            ),
-            if (_error != null)
-              Padding(
-                padding: const EdgeInsets.only(top: 8),
-                child: Text(
-                  _error!,
-                  style: Theme.of(context).textTheme.bodySmall?.copyWith(
-                    color: Theme.of(context).colorScheme.error,
-                  ),
-                ),
-              ),
-            const SizedBox(height: 16),
-            FilledButton(
-              onPressed: _submit,
-              child: Text(context.l10n.common_action_save),
-            ),
-          ],
-        ),
-      ),
-    );
-  }
-
-  Widget _cylinderRow(
-    BuildContext context,
-    AppSettings settings,
-    UnitFormatter units,
-  ) {
-    // Sourced from the diver's global tank presets (issue #1335 follow-up),
-    // same as BlenderBillingCard._cylinderRow: the blender keeps no cylinder
-    // vault of its own, so this sheet's picker reads the same list.
-    final presetsAsync = ref.watch(tankPresetsProvider);
-    return Row(
-      crossAxisAlignment: CrossAxisAlignment.start,
-      children: [
-        Expanded(
-          child: TextField(
-            key: const Key('blender-line-cylinder'),
-            controller: _cylinder,
-            keyboardType: const TextInputType.numberWithOptions(decimal: true),
-            inputFormatters: [
-              FilteringTextInputFormatter.allow(RegExp(r'[0-9.,]')),
-            ],
-            decoration: InputDecoration(
-              labelText:
-                  '${context.l10n.gasCalculators_blender_cylinderVolume} '
-                  '(${units.volumeSymbol})',
-              isDense: true,
-              border: const OutlineInputBorder(),
-            ),
-          ),
-        ),
-        const SizedBox(width: 8),
-        presetsAsync.when(
-          loading: () => const Padding(
-            padding: EdgeInsets.symmetric(horizontal: 8, vertical: 12),
-            child: SizedBox(
-              width: 24,
-              height: 24,
-              child: CircularProgressIndicator(strokeWidth: 2),
-            ),
-          ),
-          error: (error, stackTrace) => IconButton(
-            icon: const Icon(Icons.error_outline),
-            tooltip: context.l10n.gasCalculators_blender_cylinderPresets,
-            onPressed: null,
-          ),
-          data: (presets) => PopupMenuButton<double>(
-            key: const Key('blender-line-cylinder-presets'),
-            tooltip: context.l10n.gasCalculators_blender_cylinderPresets,
-            position: PopupMenuPosition.under,
-            itemBuilder: (context) => [
-              for (final preset in presets)
-                PopupMenuItem<double>(
-                  value: preset.volumeLiters,
-                  child: Text(
-                    '${preset.displayName} '
-                    '(${units.formatTankVolume(preset.volumeLiters, null)})',
-                  ),
-                ),
-            ],
-            onSelected: (liters) => setState(
-              () => _cylinder.text = formatRoundedForInput(
-                litersToDisplayVolume(liters, settings),
-                2,
-              ),
-            ),
-            child: Padding(
-              padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 12),
-              child: Row(
-                mainAxisSize: MainAxisSize.min,
-                children: [
-                  Text(context.l10n.gasCalculators_blender_cylinderPresets),
-                  const Icon(Icons.arrow_drop_down),
-                ],
-              ),
-            ),
-          ),
-        ),
-      ],
-    );
-  }
-
-  Widget _numberField(
-    BuildContext context,
-    TextEditingController controller,
-    String label,
-  ) {
-    return TextField(
-      controller: controller,
-      keyboardType: const TextInputType.numberWithOptions(decimal: true),
-      inputFormatters: [FilteringTextInputFormatter.allow(RegExp(r'[0-9.,]'))],
-      decoration: InputDecoration(
-        labelText: '$label (%)',
-        isDense: true,
-        border: const OutlineInputBorder(),
-      ),
-    );
-  }
-}
diff --git a/lib/features/gas_calculators/presentation/widgets/blender/blender_line_edit_sheet.dart b/lib/features/gas_calculators/presentation/widgets/blender/blender_line_edit_sheet.dart
new file mode 100644
index 0000000000..252346403a
--- /dev/null
+++ b/lib/features/gas_calculators/presentation/widgets/blender/blender_line_edit_sheet.dart
@@ -0,0 +1,667 @@
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+import 'package:intl/intl.dart';
+import 'package:submersion/core/constants/units.dart';
+import 'package:submersion/core/providers/provider.dart';
+import 'package:submersion/core/utils/currency.dart';
+import 'package:submersion/core/utils/number_input.dart';
+import 'package:submersion/core/utils/unit_formatter.dart';
+import 'package:submersion/features/gas_calculators/domain/blending/billed_fill.dart';
+import 'package:submersion/features/gas_calculators/domain/blending/blend_billing.dart';
+import 'package:submersion/features/gas_calculators/domain/blending/blender_gas_role.dart';
+import 'package:submersion/features/gas_calculators/presentation/providers/gas_blender_providers.dart';
+import 'package:submersion/features/gas_calculators/presentation/widgets/blender/blender_formatting.dart';
+import 'package:submersion/features/gas_calculators/presentation/widgets/blender/blender_volume_conversion.dart';
+import 'package:submersion/features/settings/presentation/providers/settings_providers.dart';
+import 'package:submersion/features/tank_presets/domain/entities/tank_preset_entity.dart';
+import 'package:submersion/features/tank_presets/presentation/providers/tank_preset_providers.dart';
+import 'package:submersion/l10n/arb/app_localizations.dart';
+import 'package:submersion/l10n/l10n_extension.dart';
+
+/// The two kinds of line "Add a line" can put on the bill (issue #2302).
+enum BlenderLineKind {
+  /// One gas filled by hand, priced from the cylinder, the pressure filled
+  /// and that gas's configured price.
+  gas,
+
+  /// A lump sum typed in by hand, e.g. an O2 analyser cell.
+  amount,
+}
+
+/// What [BlenderLineEditSheet] hands back.
+class BlenderLineEdit {
+  const BlenderLineEdit({
+    required this.label,
+    required this.amount,
+    this.lines,
+  });
+
+  final String label;
+  final double? amount;
+
+  /// The line's itemisation: empty for a free amount, the single gas line of
+  /// a gas fill. Null leaves the edited fill's own lines untouched, which is
+  /// what a fill the blender computed needs.
+  final List<BilledGasLine>? lines;
+}
+
+/// Adds a line to the running bill, or edits one already on it.
+///
+/// Owns its own controllers, and disposes them in its own State.
+///
+/// Creating them in the caller and disposing on the sheet's future looks
+/// equivalent and is not: the future completes when the route is popped, while
+/// the exit transition keeps rebuilding these fields for several more frames
+/// against a controller that is already gone.
+///
+/// A scrollable, keyboard-aware bottom sheet rather than a fixed-size
+/// `AlertDialog`: the gas fill needs a cylinder row and two pressure fields,
+/// and a taller fixed dialog risks overflow once the keyboard is up on the
+/// narrowest phone the app supports (issue #1335).
+class BlenderLineEditSheet extends ConsumerStatefulWidget {
+  const BlenderLineEditSheet({super.key, required this.fill});
+
+  /// Null to add a new line.
+  final BilledFill? fill;
+
+  @override
+  ConsumerState<BlenderLineEditSheet> createState() =>
+      _BlenderLineEditSheetState();
+}
+
+class _BlenderLineEditSheetState extends ConsumerState<BlenderLineEditSheet> {
+  late final TextEditingController _label;
+  late final TextEditingController _amount;
+  late final TextEditingController _cylinder;
+  late final TextEditingController _startPressure;
+  late final TextEditingController _endPressure;
+
+  late BlenderLineKind _kind;
+  late BlenderGasRole _role;
+
+  /// The exact water volume of the cylinder preset last picked, until the
+  /// field is typed into. The field shows it rounded, which in cubic feet
+  /// loses enough to misprice the fill if it were read back from the text.
+  double? _presetLiters;
+
+  /// The gas fill fields as the sheet opened them, to tell an edit of the
+  /// description alone from a changed fill.
+  late final String _seedCylinder;
+  late final String _seedStart;
+  late final String _seedEnd;
+
+  String? _error;
+
+  /// Only a new line or one entered by hand may pick its kind. A fill the
+  /// blender computed is already itemised in [BilledFill.lines]; offering a
+  /// gas or an amount here would let the label and the itemisation disagree.
+  bool get _kindEditable {
+    final fill = widget.fill;
+    return fill == null || fill.isManual || fill.manualGasLine != null;
+  }
+
+  @override
+  void initState() {
+    super.initState();
+    final fill = widget.fill;
+    final gasLine = fill?.manualGasLine;
+    final settings = ref.read(settingsProvider);
+    final units = UnitFormatter(settings);
+
+    _kind = fill == null || gasLine != null
+        ? BlenderLineKind.gas
+        : BlenderLineKind.amount;
+    _role = gasLine?.role ?? BlenderGasRole.o2;
+
+    // A label this sheet generated is left blank rather than kept as typed
+    // text, so changing the pressure or the gas regenerates it. Checked in
+    // every unit combination and app language: the diver may have switched
+    // either since.
+    final generated =
+        gasLine != null && _isGeneratedLabel(fill!.label, gasLine, settings);
+    _label = TextEditingController(
+      text: fill == null || generated ? '' : fill.label,
+    );
+    // Seeded for a gas fill too: switching it to a free amount starts from
+    // what it cost rather than from a blank that would leave it unpriced.
+    _amount = TextEditingController(
+      text: fill?.total == null ? '' : formatRoundedForInput(fill!.total!, 2),
+    );
+    final double cylinderLiters =
+        gasLine?.cylinderLiters ?? ref.read(blenderCylinderLitersProvider);
+    _seedCylinder = formatRoundedForInput(
+      litersToDisplayVolume(cylinderLiters, settings),
+      2,
+    );
+    _cylinder = TextEditingController(text: _seedCylinder);
+    final double startBar = gasLine?.startBar ?? 0;
+    final double endBar =
+        gasLine?.endBar ?? ref.read(blenderTargetPressureProvider);
+    // Two decimals rather than whole numbers, so reopening a fill and saving
+    // it untouched cannot move its pressures.
+    _seedStart = formatRoundedForInput(units.convertPressure(startBar), 2);
+    _seedEnd = formatRoundedForInput(units.convertPressure(endBar), 2);
+    _startPressure = TextEditingController(text: _seedStart);
+    _endPressure = TextEditingController(text: _seedEnd);
+  }
+
+  /// The saved gas fill being edited, when none of its fill fields has
+  /// changed. It then keeps the amount and gas name it was billed with: a
+  /// price or topup gas changed since must not reprice a line reopened only
+  /// to fix its description.
+  BilledGasLine? get _unchangedGasLine {
+    final line = widget.fill?.manualGasLine;
+    if (line == null || line.role != _role || _presetLiters != null) {
+      return null;
+    }
+    if (_cylinder.text != _seedCylinder ||
+        _startPressure.text != _seedStart ||
+        _endPressure.text != _seedEnd) {
+      return null;
+    }
+    return line;
+  }
+
+  @override
+  void dispose() {
+    _label.dispose();
+    _amount.dispose();
+    _cylinder.dispose();
+    _startPressure.dispose();
+    _endPressure.dispose();
+    super.dispose();
+  }
+
+  /// Whether [label] is what [_generatedLabel] made for [line], in any
+  /// pressure and volume unit and under any of the app's languages.
+  ///
+  /// The language matters because the label's numbers carry that locale's
+  /// decimal separator: "12,5 L" written under de is not "12.5 L" read back
+  /// under en.
+  bool _isGeneratedLabel(
+    String label,
+    BilledGasLine line,
+    AppSettings settings,
+  ) {
+    for (final locale in AppLocalizations.supportedLocales) {
+      for (final pressure in PressureUnit.values) {
+        for (final volume in VolumeUnit.values) {
+          final units = UnitFormatter(
+            settings.copyWith(pressureUnit: pressure, volumeUnit: volume),
+          );
+          final candidate = Intl.withLocale(
+            locale.toLanguageTag(),
+            () => _generatedLabel(
+              line.gas,
+              line.cylinderLiters,
+              line.addedBar,
+              units,
+            ),
+          );
+          if (label == candidate) return true;
+        }
+      }
+    }
+    return false;
+  }
+
+  String _generatedLabel(
+    String gasName,
+    double? cylinderLiters,
+    double addedBar,
+    UnitFormatter units,
+  ) => [
+    gasName,
+    if (cylinderLiters != null) units.formatTankVolume(cylinderLiters, null),
+    // The blender's own pressure precision, so a label reads the fill that
+    // was billed rather than a rounded one.
+    units.formatPressure(
+      addedBar,
+      decimals: pressureDecimalsFor(units.settings.pressureUnit),
+    ),
+  ].join(' · ');
+
+  /// The name the chosen gas is stored and printed under, the same one a
+  /// computed fill's line would carry for it.
+  String _gasName(BlenderGasRole role) => formatPreciseGasName(
+    context,
+    gasForRole(role, ref.read(blenderTopupO2PercentProvider)),
+  );
+
+  /// The dropdown entry for [role]. The topup gas names what it currently
+  /// holds, since that is configurable and not always air.
+  String _roleOption(BlenderGasRole role, double topupO2) {
+    final label = blenderGasRoleLabel(context, role);
+    if (role != BlenderGasRole.topup) return label;
+    return '$label (${formatPreciseMix(context, gasForRole(role, topupO2))})';
+  }
+
+  double? _priceFor(BlenderGasRole role, List<double?> prices) =>
+      role.index < prices.length ? prices[role.index] : null;
+
+  double? _cylinderLiters(AppSettings settings) {
+    if (_presetLiters != null) return _presetLiters;
+    // An untouched field still holds the saved fill's exact volume, which
+    // its rounded text would lose in cubic feet.
+    final saved = widget.fill?.manualGasLine?.cylinderLiters;
+    if (saved != null && _cylinder.text == _seedCylinder) return saved;
+    final shown = smartParseUserDecimal(_cylinder.text);
+    if (shown == null || shown <= 0) return null;
+    return displayVolumeToLiters(shown, settings);
+  }
+
+  /// The gas fill as currently entered, or null while it cannot be priced.
+  ManualGasFillCost? _gasCost(
+    AppSettings settings,
+    UnitFormatter units,
+    List<double?> prices,
+  ) {
+    final liters = _cylinderLiters(settings);
+    final start = smartParseUserDecimal(_startPressure.text);
+    final end = smartParseUserDecimal(_endPressure.text);
+    if (liters == null || start == null || end == null) return null;
+    return manualGasFillCost(
+      waterLiters: liters,
+      startBar: units.pressureToBar(start),
+      endBar: units.pressureToBar(end),
+      pricePer100: _priceFor(_role, prices),
+    );
+  }
+
+  void _submit() {
+    final label = _label.text.trim();
+    if (!_kindEditable || _kind == BlenderLineKind.amount) {
+      if (label.isEmpty) {
+        setState(
+          () =>
+              _error = context.l10n.gasCalculators_blender_lineNeedsDescription,
+        );
+        return;
+      }
+      Navigator.of(context).pop(
+        BlenderLineEdit(
+          label: label,
+          amount: smartParseUserDecimal(_amount.text),
+          lines: _kindEditable ? const [] : null,
+        ),
+      );
+      return;
+    }
+
+    final settings = ref.read(settingsProvider);
+    final units = UnitFormatter(settings);
+    final unchanged = _unchangedGasLine;
+    if (unchanged != null) {
+      final fill = widget.fill!;
+      Navigator.of(context).pop(
+        BlenderLineEdit(
+          // A blank description here means the saved one was generated, so
+          // it is kept as saved: the fill did not change, and regenerating
+          // it would only restate it in whatever unit is active now.
+          label: label.isNotEmpty ? label : fill.label,
+          amount: fill.total,
+          lines: [unchanged],
+        ),
+      );
+      return;
+    }
+    final liters = _cylinderLiters(settings);
+    if (liters == null) {
+      setState(
+        () => _error = context.l10n.gasCalculators_blender_lineNeedsCylinder,
+      );
+      return;
+    }
+    if (smartParseUserDecimal(_startPressure.text) == null ||
+        smartParseUserDecimal(_endPressure.text) == null) {
+      setState(
+        () => _error = context.l10n.gasCalculators_blender_lineNeedsPressure,
+      );
+      return;
+    }
+    final cost = _gasCost(settings, units, ref.read(blenderGasPricesProvider));
+    if (cost == null) {
+      setState(
+        () => _error = context.l10n.gasCalculators_blender_lineInvalidPressure,
+      );
+      return;
+    }
+    final gasName = _gasName(_role);
+    final startBar = units.pressureToBar(
+      smartParseUserDecimal(_startPressure.text)!,
+    );
+    Navigator.of(context).pop(
+      BlenderLineEdit(
+        label: label.isNotEmpty
+            ? label
+            : _generatedLabel(gasName, liters, cost.addedBar, units),
+        amount: cost.cost,
+        lines: [
+          BilledGasLine(
+            gas: gasName,
+            addedBar: cost.addedBar,
+            cost: cost.cost,
+            freeGasLiters: cost.freeGasLiters,
+            cylinderLiters: liters,
+            role: _role,
+            startBar: startBar,
+          ),
+        ],
+      ),
+    );
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final fill = widget.fill;
+    final settings = ref.watch(settingsProvider);
+    final units = UnitFormatter(settings);
+    final isGas = _kindEditable && _kind == BlenderLineKind.gas;
+    return Padding(
+      padding: EdgeInsets.only(
+        left: 16,
+        right: 16,
+        top: 16,
+        bottom: MediaQuery.of(context).viewInsets.bottom + 16,
+      ),
+      child: SingleChildScrollView(
+        child: Column(
+          mainAxisSize: MainAxisSize.min,
+          crossAxisAlignment: CrossAxisAlignment.stretch,
+          children: [
+            Text(
+              fill == null
+                  ? context.l10n.gasCalculators_blender_addManualLine
+                  : context.l10n.gasCalculators_blender_editLine(fill.label),
+              style: Theme.of(context).textTheme.titleMedium,
+            ),
+            const SizedBox(height: 16),
+            if (_kindEditable) ...[
+              SegmentedButton<BlenderLineKind>(
+                key: const Key('blender-line-kind'),
+                segments: [
+                  ButtonSegment(
+                    value: BlenderLineKind.gas,
+                    label: Text(
+                      context.l10n.gasCalculators_blender_lineKindGas,
+                    ),
+                  ),
+                  ButtonSegment(
+                    value: BlenderLineKind.amount,
+                    label: Text(
+                      context.l10n.gasCalculators_blender_lineKindAmount,
+                    ),
+                  ),
+                ],
+                selected: {_kind},
+                onSelectionChanged: (selection) => setState(() {
+                  _kind = selection.single;
+                  _error = null;
+                  // A free amount needs a description, and a generated one
+                  // was left blank: carry the line's label over rather than
+                  // make the diver retype it.
+                  final fill = widget.fill;
+                  if (_kind == BlenderLineKind.amount &&
+                      _label.text.trim().isEmpty &&
+                      fill != null) {
+                    _label.text = fill.label;
+                  }
+                }),
+              ),
+              const SizedBox(height: 12),
+            ],
+            TextField(
+              key: const Key('blender-line-description'),
+              controller: _label,
+              autofocus: !isGas,
+              decoration: InputDecoration(
+                labelText: context.l10n.gasCalculators_blender_lineDescription,
+                helperText: isGas
+                    ? context
+                          .l10n
+                          .gasCalculators_blender_lineDescriptionOptional
+                    : null,
+                isDense: true,
+                border: const OutlineInputBorder(),
+              ),
+            ),
+            const SizedBox(height: 12),
+            if (isGas)
+              ..._gasFields(context, settings, units)
+            else
+              TextField(
+                key: const Key('blender-line-amount'),
+                controller: _amount,
+                keyboardType: const TextInputType.numberWithOptions(
+                  decimal: true,
+                ),
+                onSubmitted: (_) => _submit(),
+                decoration: InputDecoration(
+                  labelText: context.l10n.gasCalculators_blender_lineAmount,
+                  isDense: true,
+                  border: const OutlineInputBorder(),
+                ),
+              ),
+            if (_error != null)
+              Padding(
+                padding: const EdgeInsets.only(top: 8),
+                child: Text(
+                  _error!,
+                  style: Theme.of(context).textTheme.bodySmall?.copyWith(
+                    color: Theme.of(context).colorScheme.error,
+                  ),
+                ),
+              ),
+            const SizedBox(height: 16),
+            FilledButton(
+              onPressed: _submit,
+              child: Text(context.l10n.common_action_save),
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+
+  List<Widget> _gasFields(
+    BuildContext context,
+    AppSettings settings,
+    UnitFormatter units,
+  ) {
+    final theme = Theme.of(context);
+    final prices = ref.watch(blenderGasPricesProvider);
+    final topupO2 = ref.watch(blenderTopupO2PercentProvider);
+    final currency = ref.watch(blenderCurrencyProvider);
+    // An untouched saved fill shows what it was billed at, the same amount
+    // saving it will keep.
+    final unchanged = _unchangedGasLine;
+    final cost = unchanged == null ? _gasCost(settings, units, prices) : null;
+    final addedBar = unchanged?.addedBar ?? cost?.addedBar;
+    final amount = unchanged != null ? widget.fill!.total : cost?.cost;
+    final unpriced = unchanged == null && _priceFor(_role, prices) == null;
+    final resultStyle = theme.textTheme.titleSmall;
+    return [
+      DropdownButtonFormField<BlenderGasRole>(
+        key: const Key('blender-line-gas'),
+        initialValue: _role,
+        decoration: InputDecoration(
+          labelText: context.l10n.gasCalculators_blender_lineGas,
+          isDense: true,
+          border: const OutlineInputBorder(),
+        ),
+        items: [
+          for (final role in BlenderGasRole.values)
+            DropdownMenuItem(
+              value: role,
+              child: Text(_roleOption(role, topupO2)),
+            ),
+        ],
+        onChanged: (role) {
+          if (role != null) setState(() => _role = role);
+        },
+      ),
+      const SizedBox(height: 12),
+      _cylinderRow(context, settings, units),
+      const SizedBox(height: 12),
+      Row(
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          Expanded(
+            child: _numberField(
+              const Key('blender-line-start-pressure'),
+              _startPressure,
+              '${context.l10n.gasCalculators_blender_lineStartPressure} '
+              '(${units.pressureSymbol})',
+            ),
+          ),
+          const SizedBox(width: 8),
+          Expanded(
+            child: _numberField(
+              const Key('blender-line-end-pressure'),
+              _endPressure,
+              '${context.l10n.gasCalculators_blender_lineEndPressure} '
+              '(${units.pressureSymbol})',
+            ),
+          ),
+        ],
+      ),
+      const SizedBox(height: 12),
+      Text(
+        context.l10n.gasCalculators_blender_lineFillPressure(
+          addedBar == null
+              ? '--'
+              : units.formatPressure(
+                  addedBar,
+                  decimals: pressureDecimalsFor(settings.pressureUnit),
+                ),
+        ),
+        key: const Key('blender-line-fill-pressure'),
+        style: resultStyle,
+      ),
+      const SizedBox(height: 4),
+      Text(
+        context.l10n.gasCalculators_blender_lineComputedAmount(
+          amount == null ? '--' : formatMoney(amount, currency),
+        ),
+        key: const Key('blender-line-computed-amount'),
+        style: resultStyle?.copyWith(fontWeight: FontWeight.w700),
+      ),
+      if (unpriced)
+        Padding(
+          padding: const EdgeInsets.only(top: 4),
+          child: Text(
+            context.l10n.gasCalculators_blender_lineNoPrice,
+            key: const Key('blender-line-no-price'),
+            style: theme.textTheme.bodySmall?.copyWith(
+              color: theme.colorScheme.onSurfaceVariant,
+            ),
+          ),
+        ),
+    ];
+  }
+
+  Widget _cylinderRow(
+    BuildContext context,
+    AppSettings settings,
+    UnitFormatter units,
+  ) {
+    // Sourced from the diver's global tank presets (issue #1335 follow-up),
+    // same as BlenderBillingCard._cylinderRow: the blender keeps no cylinder
+    // vault of its own, so this sheet's picker reads the same list.
+    final presetsAsync = ref.watch(tankPresetsProvider);
+    return Row(
+      crossAxisAlignment: CrossAxisAlignment.start,
+      children: [
+        Expanded(
+          child: _numberField(
+            const Key('blender-line-cylinder'),
+            _cylinder,
+            '${context.l10n.gasCalculators_blender_cylinderVolume} '
+            '(${units.volumeSymbol})',
+            // Typing a size replaces the preset's exact one.
+            onChanged: () => _presetLiters = null,
+          ),
+        ),
+        const SizedBox(width: 8),
+        presetsAsync.when(
+          loading: () => const Padding(
+            padding: EdgeInsets.symmetric(horizontal: 8, vertical: 12),
+            child: SizedBox(
+              width: 24,
+              height: 24,
+              child: CircularProgressIndicator(strokeWidth: 2),
+            ),
+          ),
+          error: (error, stackTrace) => IconButton(
+            icon: const Icon(Icons.error_outline),
+            tooltip: context.l10n.gasCalculators_blender_cylinderPresets,
+            onPressed: null,
+          ),
+          data: (presets) => PopupMenuButton<TankPresetEntity>(
+            key: const Key('blender-line-cylinder-presets'),
+            tooltip: context.l10n.gasCalculators_blender_cylinderPresets,
+            position: PopupMenuPosition.under,
+            itemBuilder: (context) => [
+              for (final preset in presets)
+                PopupMenuItem<TankPresetEntity>(
+                  value: preset,
+                  child: Text(
+                    '${preset.displayName} '
+                    '(${units.formatTankVolume(preset.volumeLiters, null)})',
+                  ),
+                ),
+            ],
+            // A preset sets the end pressure too: its working pressure is
+            // what the cylinder is filled to (issue #2302). Still editable
+            // afterwards, since only the last gas of a blend reaches it.
+            onSelected: (preset) => setState(() {
+              _presetLiters = preset.volumeLiters;
+              _cylinder.text = formatRoundedForInput(
+                litersToDisplayVolume(preset.volumeLiters, settings),
+                2,
+              );
+              _endPressure.text = formatRoundedForInput(
+                units.convertPressure(preset.workingPressureBar),
+                2,
+              );
+              _error = null;
+            }),
+            child: Padding(
+              padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 12),
+              child: Row(
+                mainAxisSize: MainAxisSize.min,
+                children: [
+                  Text(context.l10n.gasCalculators_blender_cylinderPresets),
+                  const Icon(Icons.arrow_drop_down),
+                ],
+              ),
+            ),
+          ),
+        ),
+      ],
+    );
+  }
+
+  Widget _numberField(
+    Key key,
+    TextEditingController controller,
+    String label, {
+    VoidCallback? onChanged,
+  }) {
+    return TextField(
+      key: key,
+      controller: controller,
+      keyboardType: const TextInputType.numberWithOptions(decimal: true),
+      inputFormatters: [FilteringTextInputFormatter.allow(RegExp(r'[0-9.,]'))],
+      onChanged: (_) => setState(() {
+        onChanged?.call();
+        _error = null;
+      }),
+      decoration: InputDecoration(
+        labelText: label,
+        isDense: true,
+        border: const OutlineInputBorder(),
+      ),
+    );
+  }
+}
diff --git a/lib/l10n/arb/app_ar.arb b/lib/l10n/arb/app_ar.arb
index 1458357a37..95ccae8d45 100644
--- a/lib/l10n/arb/app_ar.arb
+++ b/lib/l10n/arb/app_ar.arb
@@ -142,7 +142,19 @@
   "gasCalculators_blender_addManualLine": "إضافة بند",
   "gasCalculators_blender_lineDescription": "الوصف",
   "gasCalculators_blender_lineAmount": "المبلغ",
-  "gasCalculators_blender_lineNeedsDescription": "أدخل وصفًا، أو أسطوانة ومزيجًا.",
+  "gasCalculators_blender_lineNeedsDescription": "أدخل وصفًا.",
+  "gasCalculators_blender_lineKindGas": "تعبئة غاز",
+  "gasCalculators_blender_lineKindAmount": "مبلغ حر",
+  "gasCalculators_blender_lineGas": "التعبئة",
+  "gasCalculators_blender_lineStartPressure": "الضغط الابتدائي",
+  "gasCalculators_blender_lineEndPressure": "الضغط النهائي",
+  "gasCalculators_blender_lineFillPressure": "ضغط التعبئة: {pressure}",
+  "gasCalculators_blender_lineComputedAmount": "المبلغ: {amount}",
+  "gasCalculators_blender_lineNoPrice": "لم يُحدَّد سعر لهذا الغاز، لذا يُحتسب بصفر.",
+  "gasCalculators_blender_lineInvalidPressure": "يجب أن يكون الضغط النهائي أعلى من الضغط الابتدائي.",
+  "gasCalculators_blender_lineNeedsPressure": "أدخل ضغطًا ابتدائيًا وضغطًا نهائيًا.",
+  "gasCalculators_blender_lineNeedsCylinder": "أدخل سعة الأسطوانة.",
+  "gasCalculators_blender_lineDescriptionOptional": "اختياري. إذا تُرك فارغًا، يُنشأ من التعبئة.",
   "gasCalculators_blender_export": "تصدير",
   "gasCalculators_blender_exportPdf": "تصدير كملف PDF",
   "gasCalculators_blender_exportImage": "تصدير كصورة",
diff --git a/lib/l10n/arb/app_de.arb b/lib/l10n/arb/app_de.arb
index 818cde2c6d..f668395938 100644
--- a/lib/l10n/arb/app_de.arb
+++ b/lib/l10n/arb/app_de.arb
@@ -150,7 +150,19 @@
   "gasCalculators_blender_addManualLine": "Position hinzufügen",
   "gasCalculators_blender_lineDescription": "Bezeichnung",
   "gasCalculators_blender_lineAmount": "Betrag",
-  "gasCalculators_blender_lineNeedsDescription": "Gib eine Beschreibung oder Flasche und Mischung ein.",
+  "gasCalculators_blender_lineNeedsDescription": "Gib eine Bezeichnung ein.",
+  "gasCalculators_blender_lineKindGas": "Gasfüllung",
+  "gasCalculators_blender_lineKindAmount": "Freier Betrag",
+  "gasCalculators_blender_lineGas": "Füllung",
+  "gasCalculators_blender_lineStartPressure": "Anfangsdruck",
+  "gasCalculators_blender_lineEndPressure": "Enddruck",
+  "gasCalculators_blender_lineFillPressure": "Fülldruck: {pressure}",
+  "gasCalculators_blender_lineComputedAmount": "Betrag: {amount}",
+  "gasCalculators_blender_lineNoPrice": "Für dieses Gas ist kein Preis hinterlegt, es wird mit 0 berechnet.",
+  "gasCalculators_blender_lineInvalidPressure": "Der Enddruck muss über dem Anfangsdruck liegen.",
+  "gasCalculators_blender_lineNeedsPressure": "Gib einen Anfangs- und einen Enddruck ein.",
+  "gasCalculators_blender_lineNeedsCylinder": "Gib ein Flaschenvolumen ein.",
+  "gasCalculators_blender_lineDescriptionOptional": "Optional. Bleibt das Feld leer, wird die Bezeichnung aus der Füllung erzeugt.",
   "gasCalculators_blender_export": "Exportieren",
   "gasCalculators_blender_exportPdf": "Als PDF exportieren",
   "gasCalculators_blender_exportImage": "Als Bild exportieren",
diff --git a/lib/l10n/arb/app_en.arb b/lib/l10n/arb/app_en.arb
index 0d4e19ec61..cf96e29094 100644
--- a/lib/l10n/arb/app_en.arb
+++ b/lib/l10n/arb/app_en.arb
@@ -8310,7 +8310,33 @@
   "gasCalculators_blender_addManualLine": "Add a line",
   "gasCalculators_blender_lineDescription": "Description",
   "gasCalculators_blender_lineAmount": "Amount",
-  "gasCalculators_blender_lineNeedsDescription": "Enter a description, or a cylinder and mix.",
+  "gasCalculators_blender_lineNeedsDescription": "Enter a description.",
+  "gasCalculators_blender_lineKindGas": "Gas fill",
+  "gasCalculators_blender_lineKindAmount": "Free amount",
+  "gasCalculators_blender_lineGas": "Fill",
+  "gasCalculators_blender_lineStartPressure": "Start pressure",
+  "gasCalculators_blender_lineEndPressure": "End pressure",
+  "gasCalculators_blender_lineFillPressure": "Fill pressure: {pressure}",
+  "gasCalculators_blender_lineComputedAmount": "Amount: {amount}",
+  "gasCalculators_blender_lineNoPrice": "No price is set for this gas, so it is charged at 0.",
+  "gasCalculators_blender_lineInvalidPressure": "The end pressure must be above the start pressure.",
+  "gasCalculators_blender_lineNeedsPressure": "Enter a start and an end pressure.",
+  "gasCalculators_blender_lineNeedsCylinder": "Enter a cylinder volume.",
+  "gasCalculators_blender_lineDescriptionOptional": "Optional. Left empty, it is generated from the fill.",
+  "@gasCalculators_blender_lineFillPressure": {
+    "placeholders": {
+      "pressure": {
+        "type": "String"
+      }
+    }
+  },
+  "@gasCalculators_blender_lineComputedAmount": {
+    "placeholders": {
+      "amount": {
+        "type": "String"
+      }
+    }
+  },
   "gasCalculators_blender_export": "Export",
   "gasCalculators_blender_exportPdf": "Export as PDF",
   "gasCalculators_blender_exportImage": "Export as Image",
diff --git a/lib/l10n/arb/app_es.arb b/lib/l10n/arb/app_es.arb
index a9e00452b7..2953f5baf4 100644
--- a/lib/l10n/arb/app_es.arb
+++ b/lib/l10n/arb/app_es.arb
@@ -142,7 +142,19 @@
   "gasCalculators_blender_addManualLine": "Añadir una línea",
   "gasCalculators_blender_lineDescription": "Descripción",
   "gasCalculators_blender_lineAmount": "Importe",
-  "gasCalculators_blender_lineNeedsDescription": "Introduce una descripción, o un cilindro y una mezcla.",
+  "gasCalculators_blender_lineNeedsDescription": "Introduce una descripción.",
+  "gasCalculators_blender_lineKindGas": "Llenado de gas",
+  "gasCalculators_blender_lineKindAmount": "Importe libre",
+  "gasCalculators_blender_lineGas": "Llenado",
+  "gasCalculators_blender_lineStartPressure": "Presión inicial",
+  "gasCalculators_blender_lineEndPressure": "Presión final",
+  "gasCalculators_blender_lineFillPressure": "Presión de llenado: {pressure}",
+  "gasCalculators_blender_lineComputedAmount": "Importe: {amount}",
+  "gasCalculators_blender_lineNoPrice": "No hay precio para este gas, así que se cobra a 0.",
+  "gasCalculators_blender_lineInvalidPressure": "La presión final debe ser mayor que la inicial.",
+  "gasCalculators_blender_lineNeedsPressure": "Introduce una presión inicial y una final.",
+  "gasCalculators_blender_lineNeedsCylinder": "Introduce un volumen de cilindro.",
+  "gasCalculators_blender_lineDescriptionOptional": "Opcional. Si se deja vacío, se genera a partir del llenado.",
   "gasCalculators_blender_export": "Exportar",
   "gasCalculators_blender_exportPdf": "Exportar como PDF",
   "gasCalculators_blender_exportImage": "Exportar como imagen",
diff --git a/lib/l10n/arb/app_fr.arb b/lib/l10n/arb/app_fr.arb
index 709f29c1eb..0bc9660c81 100644
--- a/lib/l10n/arb/app_fr.arb
+++ b/lib/l10n/arb/app_fr.arb
@@ -142,7 +142,19 @@
   "gasCalculators_blender_addManualLine": "Ajouter une ligne",
   "gasCalculators_blender_lineDescription": "Désignation",
   "gasCalculators_blender_lineAmount": "Montant",
-  "gasCalculators_blender_lineNeedsDescription": "Saisissez une description, ou une bouteille et un mélange.",
+  "gasCalculators_blender_lineNeedsDescription": "Saisissez une description.",
+  "gasCalculators_blender_lineKindGas": "Gonflage de gaz",
+  "gasCalculators_blender_lineKindAmount": "Montant libre",
+  "gasCalculators_blender_lineGas": "Gonflage",
+  "gasCalculators_blender_lineStartPressure": "Pression initiale",
+  "gasCalculators_blender_lineEndPressure": "Pression finale",
+  "gasCalculators_blender_lineFillPressure": "Pression de gonflage : {pressure}",
+  "gasCalculators_blender_lineComputedAmount": "Montant : {amount}",
+  "gasCalculators_blender_lineNoPrice": "Aucun prix n'est défini pour ce gaz, il est facturé à 0.",
+  "gasCalculators_blender_lineInvalidPressure": "La pression finale doit être supérieure à la pression initiale.",
+  "gasCalculators_blender_lineNeedsPressure": "Saisissez une pression initiale et une pression finale.",
+  "gasCalculators_blender_lineNeedsCylinder": "Saisissez un volume de bloc.",
+  "gasCalculators_blender_lineDescriptionOptional": "Facultatif. Laissé vide, il est généré à partir du gonflage.",
   "gasCalculators_blender_export": "Exporter",
   "gasCalculators_blender_exportPdf": "Exporter en PDF",
   "gasCalculators_blender_exportImage": "Exporter en image",
diff --git a/lib/l10n/arb/app_he.arb b/lib/l10n/arb/app_he.arb
index cd1a44d369..688204c8f6 100644
--- a/lib/l10n/arb/app_he.arb
+++ b/lib/l10n/arb/app_he.arb
@@ -142,7 +142,19 @@
   "gasCalculators_blender_addManualLine": "הוסף שורה",
   "gasCalculators_blender_lineDescription": "תיאור",
   "gasCalculators_blender_lineAmount": "סכום",
-  "gasCalculators_blender_lineNeedsDescription": "יש להזין תיאור, או מכל ותערובת.",
+  "gasCalculators_blender_lineNeedsDescription": "יש להזין תיאור.",
+  "gasCalculators_blender_lineKindGas": "מילוי גז",
+  "gasCalculators_blender_lineKindAmount": "סכום חופשי",
+  "gasCalculators_blender_lineGas": "מילוי",
+  "gasCalculators_blender_lineStartPressure": "לחץ התחלתי",
+  "gasCalculators_blender_lineEndPressure": "לחץ סופי",
+  "gasCalculators_blender_lineFillPressure": "לחץ מילוי: {pressure}",
+  "gasCalculators_blender_lineComputedAmount": "סכום: {amount}",
+  "gasCalculators_blender_lineNoPrice": "לא הוגדר מחיר לגז זה, ולכן הוא מחויב ב-0.",
+  "gasCalculators_blender_lineInvalidPressure": "הלחץ הסופי חייב להיות גבוה מהלחץ ההתחלתי.",
+  "gasCalculators_blender_lineNeedsPressure": "יש להזין לחץ התחלתי ולחץ סופי.",
+  "gasCalculators_blender_lineNeedsCylinder": "יש להזין נפח מכל.",
+  "gasCalculators_blender_lineDescriptionOptional": "אופציונלי. אם יישאר ריק, הוא ייווצר מתוך המילוי.",
   "gasCalculators_blender_export": "ייצוא",
   "gasCalculators_blender_exportPdf": "ייצוא כ-PDF",
   "gasCalculators_blender_exportImage": "ייצוא כתמונה",
diff --git a/lib/l10n/arb/app_hu.arb b/lib/l10n/arb/app_hu.arb
index 541940afdb..2b24aa0aed 100644
--- a/lib/l10n/arb/app_hu.arb
+++ b/lib/l10n/arb/app_hu.arb
@@ -142,7 +142,19 @@
   "gasCalculators_blender_addManualLine": "Tétel hozzáadása",
   "gasCalculators_blender_lineDescription": "Megnevezés",
   "gasCalculators_blender_lineAmount": "Összeg",
-  "gasCalculators_blender_lineNeedsDescription": "Adjon meg egy leírást, vagy egy palackot és keveréket.",
+  "gasCalculators_blender_lineNeedsDescription": "Adjon meg egy leírást.",
+  "gasCalculators_blender_lineKindGas": "Gáztöltés",
+  "gasCalculators_blender_lineKindAmount": "Szabad összeg",
+  "gasCalculators_blender_lineGas": "Töltés",
+  "gasCalculators_blender_lineStartPressure": "Kezdőnyomás",
+  "gasCalculators_blender_lineEndPressure": "Végnyomás",
+  "gasCalculators_blender_lineFillPressure": "Töltési nyomás: {pressure}",
+  "gasCalculators_blender_lineComputedAmount": "Összeg: {amount}",
+  "gasCalculators_blender_lineNoPrice": "Ehhez a gázhoz nincs ár megadva, ezért 0-val számolunk.",
+  "gasCalculators_blender_lineInvalidPressure": "A végnyomásnak nagyobbnak kell lennie a kezdőnyomásnál.",
+  "gasCalculators_blender_lineNeedsPressure": "Adjon meg egy kezdő- és egy végnyomást.",
+  "gasCalculators_blender_lineNeedsCylinder": "Adja meg a palack térfogatát.",
+  "gasCalculators_blender_lineDescriptionOptional": "Nem kötelező. Ha üresen marad, a töltésből jön létre.",
   "gasCalculators_blender_export": "Exportálás",
   "gasCalculators_blender_exportPdf": "Exportálás PDF-be",
   "gasCalculators_blender_exportImage": "Exportálás képként",
diff --git a/lib/l10n/arb/app_it.arb b/lib/l10n/arb/app_it.arb
index ce2709136d..7a9b6da2c8 100644
--- a/lib/l10n/arb/app_it.arb
+++ b/lib/l10n/arb/app_it.arb
@@ -142,7 +142,19 @@
   "gasCalculators_blender_addManualLine": "Aggiungi una voce",
   "gasCalculators_blender_lineDescription": "Descrizione",
   "gasCalculators_blender_lineAmount": "Importo",
-  "gasCalculators_blender_lineNeedsDescription": "Inserisci una descrizione, oppure una bombola e una miscela.",
+  "gasCalculators_blender_lineNeedsDescription": "Inserisci una descrizione.",
+  "gasCalculators_blender_lineKindGas": "Ricarica di gas",
+  "gasCalculators_blender_lineKindAmount": "Importo libero",
+  "gasCalculators_blender_lineGas": "Ricarica",
+  "gasCalculators_blender_lineStartPressure": "Pressione iniziale",
+  "gasCalculators_blender_lineEndPressure": "Pressione finale",
+  "gasCalculators_blender_lineFillPressure": "Pressione di ricarica: {pressure}",
+  "gasCalculators_blender_lineComputedAmount": "Importo: {amount}",
+  "gasCalculators_blender_lineNoPrice": "Nessun prezzo impostato per questo gas, quindi viene addebitato a 0.",
+  "gasCalculators_blender_lineInvalidPressure": "La pressione finale deve essere superiore a quella iniziale.",
+  "gasCalculators_blender_lineNeedsPressure": "Inserisci una pressione iniziale e una finale.",
+  "gasCalculators_blender_lineNeedsCylinder": "Inserisci un volume della bombola.",
+  "gasCalculators_blender_lineDescriptionOptional": "Facoltativo. Se lasciato vuoto, viene generato dalla ricarica.",
   "gasCalculators_blender_export": "Esporta",
   "gasCalculators_blender_exportPdf": "Esporta come PDF",
   "gasCalculators_blender_exportImage": "Esporta come immagine",
diff --git a/lib/l10n/arb/app_localizations.dart b/lib/l10n/arb/app_localizations.dart
index b56d12a971..bde573063e 100644
--- a/lib/l10n/arb/app_localizations.dart
+++ b/lib/l10n/arb/app_localizations.dart
@@ -23485,9 +23485,81 @@ abstract class AppLocalizations {
   /// No description provided for @gasCalculators_blender_lineNeedsDescription.
   ///
   /// In en, this message translates to:
-  /// **'Enter a description, or a cylinder and mix.'**
+  /// **'Enter a description.'**
   String get gasCalculators_blender_lineNeedsDescription;
 
+  /// No description provided for @gasCalculators_blender_lineKindGas.
+  ///
+  /// In en, this message translates to:
+  /// **'Gas fill'**
+  String get gasCalculators_blender_lineKindGas;
+
+  /// No description provided for @gasCalculators_blender_lineKindAmount.
+  ///
+  /// In en, this message translates to:
+  /// **'Free amount'**
+  String get gasCalculators_blender_lineKindAmount;
+
+  /// No description provided for @gasCalculators_blender_lineGas.
+  ///
+  /// In en, this message translates to:
+  /// **'Fill'**
+  String get gasCalculators_blender_lineGas;
+
+  /// No description provided for @gasCalculators_blender_lineStartPressure.
+  ///
+  /// In en, this message translates to:
+  /// **'Start pressure'**
+  String get gasCalculators_blender_lineStartPressure;
+
+  /// No description provided for @gasCalculators_blender_lineEndPressure.
+  ///
+  /// In en, this message translates to:
+  /// **'End pressure'**
+  String get gasCalculators_blender_lineEndPressure;
+
+  /// No description provided for @gasCalculators_blender_lineFillPressure.
+  ///
+  /// In en, this message translates to:
+  /// **'Fill pressure: {pressure}'**
+  String gasCalculators_blender_lineFillPressure(String pressure);
+
+  /// No description provided for @gasCalculators_blender_lineComputedAmount.
+  ///
+  /// In en, this message translates to:
+  /// **'Amount: {amount}'**
+  String gasCalculators_blender_lineComputedAmount(String amount);
+
+  /// No description provided for @gasCalculators_blender_lineNoPrice.
+  ///
+  /// In en, this message translates to:
+  /// **'No price is set for this gas, so it is charged at 0.'**
+  String get gasCalculators_blender_lineNoPrice;
+
+  /// No description provided for @gasCalculators_blender_lineInvalidPressure.
+  ///
+  /// In en, this message translates to:
+  /// **'The end pressure must be above the start pressure.'**
+  String get gasCalculators_blender_lineInvalidPressure;
+
+  /// No description provided for @gasCalculators_blender_lineNeedsPressure.
+  ///
+  /// In en, this message translates to:
+  /// **'Enter a start and an end pressure.'**
+  String get gasCalculators_blender_lineNeedsPressure;
+
+  /// No description provided for @gasCalculators_blender_lineNeedsCylinder.
+  ///
+  /// In en, this message translates to:
+  /// **'Enter a cylinder volume.'**
+  String get gasCalculators_blender_lineNeedsCylinder;
+
+  /// No description provided for @gasCalculators_blender_lineDescriptionOptional.
+  ///
+  /// In en, this message translates to:
+  /// **'Optional. Left empty, it is generated from the fill.'**
+  String get gasCalculators_blender_lineDescriptionOptional;
+
   /// No description provided for @gasCalculators_blender_export.
   ///
   /// In en, this message translates to:
diff --git a/lib/l10n/arb/app_localizations_ar.dart b/lib/l10n/arb/app_localizations_ar.dart
index 8610666523..235df60583 100644
--- a/lib/l10n/arb/app_localizations_ar.dart
+++ b/lib/l10n/arb/app_localizations_ar.dart
@@ -14008,8 +14008,51 @@ class AppLocalizationsAr extends AppLocalizations {
   String get gasCalculators_blender_lineAmount => 'المبلغ';
 
   @override
-  String get gasCalculators_blender_lineNeedsDescription =>
-      'أدخل وصفًا، أو أسطوانة ومزيجًا.';
+  String get gasCalculators_blender_lineNeedsDescription => 'أدخل وصفًا.';
+
+  @override
+  String get gasCalculators_blender_lineKindGas => 'تعبئة غاز';
+
+  @override
+  String get gasCalculators_blender_lineKindAmount => 'مبلغ حر';
+
+  @override
+  String get gasCalculators_blender_lineGas => 'التعبئة';
+
+  @override
+  String get gasCalculators_blender_lineStartPressure => 'الضغط الابتدائي';
+
+  @override
+  String get gasCalculators_blender_lineEndPressure => 'الضغط النهائي';
+
+  @override
+  String gasCalculators_blender_lineFillPressure(String pressure) {
+    return 'ضغط التعبئة: $pressure';
+  }
+
+  @override
+  String gasCalculators_blender_lineComputedAmount(String amount) {
+    return 'المبلغ: $amount';
+  }
+
+  @override
+  String get gasCalculators_blender_lineNoPrice =>
+      'لم يُحدَّد سعر لهذا الغاز، لذا يُحتسب بصفر.';
+
+  @override
+  String get gasCalculators_blender_lineInvalidPressure =>
+      'يجب أن يكون الضغط النهائي أعلى من الضغط الابتدائي.';
+
+  @override
+  String get gasCalculators_blender_lineNeedsPressure =>
+      'أدخل ضغطًا ابتدائيًا وضغطًا نهائيًا.';
+
+  @override
+  String get gasCalculators_blender_lineNeedsCylinder => 'أدخل سعة الأسطوانة.';
+
+  @override
+  String get gasCalculators_blender_lineDescriptionOptional =>
+      'اختياري. إذا تُرك فارغًا، يُنشأ من التعبئة.';
 
   @override
   String get gasCalculators_blender_export => 'تصدير';
diff --git a/lib/l10n/arb/app_localizations_de.dart b/lib/l10n/arb/app_localizations_de.dart
index cdecf4164b..204c7bef55 100644
--- a/lib/l10n/arb/app_localizations_de.dart
+++ b/lib/l10n/arb/app_localizations_de.dart
@@ -14227,7 +14227,52 @@ class AppLocalizationsDe extends AppLocalizations {
 
   @override
   String get gasCalculators_blender_lineNeedsDescription =>
-      'Gib eine Beschreibung oder Flasche und Mischung ein.';
+      'Gib eine Bezeichnung ein.';
+
+  @override
+  String get gasCalculators_blender_lineKindGas => 'Gasfüllung';
+
+  @override
+  String get gasCalculators_blender_lineKindAmount => 'Freier Betrag';
+
+  @override
+  String get gasCalculators_blender_lineGas => 'Füllung';
+
+  @override
+  String get gasCalculators_blender_lineStartPressure => 'Anfangsdruck';
+
+  @override
+  String get gasCalculators_blender_lineEndPressure => 'Enddruck';
+
+  @override
+  String gasCalculators_blender_lineFillPressure(String pressure) {
+    return 'Fülldruck: $pressure';
+  }
+
+  @override
+  String gasCalculators_blender_lineComputedAmount(String amount) {
+    return 'Betrag: $amount';
+  }
+
+  @override
+  String get gasCalculators_blender_lineNoPrice =>
+      'Für dieses Gas ist kein Preis hinterlegt, es wird mit 0 berechnet.';
+
+  @override
+  String get gasCalculators_blender_lineInvalidPressure =>
+      'Der Enddruck muss über dem Anfangsdruck liegen.';
+
+  @override
+  String get gasCalculators_blender_lineNeedsPressure =>
+      'Gib einen Anfangs- und einen Enddruck ein.';
+
+  @override
+  String get gasCalculators_blender_lineNeedsCylinder =>
+      'Gib ein Flaschenvolumen ein.';
+
+  @override
+  String get gasCalculators_blender_lineDescriptionOptional =>
+      'Optional. Bleibt das Feld leer, wird die Bezeichnung aus der Füllung erzeugt.';
 
   @override
   String get gasCalculators_blender_export => 'Exportieren';
diff --git a/lib/l10n/arb/app_localizations_en.dart b/lib/l10n/arb/app_localizations_en.dart
index 455999785e..bdc7cf46c2 100644
--- a/lib/l10n/arb/app_localizations_en.dart
+++ b/lib/l10n/arb/app_localizations_en.dart
@@ -14019,7 +14019,52 @@ class AppLocalizationsEn extends AppLocalizations {
 
   @override
   String get gasCalculators_blender_lineNeedsDescription =>
-      'Enter a description, or a cylinder and mix.';
+      'Enter a description.';
+
+  @override
+  String get gasCalculators_blender_lineKindGas => 'Gas fill';
+
+  @override
+  String get gasCalculators_blender_lineKindAmount => 'Free amount';
+
+  @override
+  String get gasCalculators_blender_lineGas => 'Fill';
+
+  @override
+  String get gasCalculators_blender_lineStartPressure => 'Start pressure';
+
+  @override
+  String get gasCalculators_blender_lineEndPressure => 'End pressure';
+
+  @override
+  String gasCalculators_blender_lineFillPressure(String pressure) {
+    return 'Fill pressure: $pressure';
+  }
+
+  @override
+  String gasCalculators_blender_lineComputedAmount(String amount) {
+    return 'Amount: $amount';
+  }
+
+  @override
+  String get gasCalculators_blender_lineNoPrice =>
+      'No price is set for this gas, so it is charged at 0.';
+
+  @override
+  String get gasCalculators_blender_lineInvalidPressure =>
+      'The end pressure must be above the start pressure.';
+
+  @override
+  String get gasCalculators_blender_lineNeedsPressure =>
+      'Enter a start and an end pressure.';
+
+  @override
+  String get gasCalculators_blender_lineNeedsCylinder =>
+      'Enter a cylinder volume.';
+
+  @override
+  String get gasCalculators_blender_lineDescriptionOptional =>
+      'Optional. Left empty, it is generated from the fill.';
 
   @override
   String get gasCalculators_blender_export => 'Export';
diff --git a/lib/l10n/arb/app_localizations_es.dart b/lib/l10n/arb/app_localizations_es.dart
index c8f726fd09..ab19c9e633 100644
--- a/lib/l10n/arb/app_localizations_es.dart
+++ b/lib/l10n/arb/app_localizations_es.dart
@@ -14233,7 +14233,52 @@ class AppLocalizationsEs extends AppLocalizations {
 
   @override
   String get gasCalculators_blender_lineNeedsDescription =>
-      'Introduce una descripción, o un cilindro y una mezcla.';
+      'Introduce una descripción.';
+
+  @override
+  String get gasCalculators_blender_lineKindGas => 'Llenado de gas';
+
+  @override
+  String get gasCalculators_blender_lineKindAmount => 'Importe libre';
+
+  @override
+  String get gasCalculators_blender_lineGas => 'Llenado';
+
+  @override
+  String get gasCalculators_blender_lineStartPressure => 'Presión inicial';
+
+  @override
+  String get gasCalculators_blender_lineEndPressure => 'Presión final';
+
+  @override
+  String gasCalculators_blender_lineFillPressure(String pressure) {
+    return 'Presión de llenado: $pressure';
+  }
+
+  @override
+  String gasCalculators_blender_lineComputedAmount(String amount) {
+    return 'Importe: $amount';
+  }
+
+  @override
+  String get gasCalculators_blender_lineNoPrice =>
+      'No hay precio para este gas, así que se cobra a 0.';
+
+  @override
+  String get gasCalculators_blender_lineInvalidPressure =>
+      'La presión final debe ser mayor que la inicial.';
+
+  @override
+  String get gasCalculators_blender_lineNeedsPressure =>
+      'Introduce una presión inicial y una final.';
+
+  @override
+  String get gasCalculators_blender_lineNeedsCylinder =>
+      'Introduce un volumen de cilindro.';
+
+  @override
+  String get gasCalculators_blender_lineDescriptionOptional =>
+      'Opcional. Si se deja vacío, se genera a partir del llenado.';
 
   @override
   String get gasCalculators_blender_export => 'Exportar';
diff --git a/lib/l10n/arb/app_localizations_fr.dart b/lib/l10n/arb/app_localizations_fr.dart
index a518dfb797..a534301796 100644
--- a/lib/l10n/arb/app_localizations_fr.dart
+++ b/lib/l10n/arb/app_localizations_fr.dart
@@ -14293,7 +14293,52 @@ class AppLocalizationsFr extends AppLocalizations {
 
   @override
   String get gasCalculators_blender_lineNeedsDescription =>
-      'Saisissez une description, ou une bouteille et un mélange.';
+      'Saisissez une description.';
+
+  @override
+  String get gasCalculators_blender_lineKindGas => 'Gonflage de gaz';
+
+  @override
+  String get gasCalculators_blender_lineKindAmount => 'Montant libre';
+
+  @override
+  String get gasCalculators_blender_lineGas => 'Gonflage';
+
+  @override
+  String get gasCalculators_blender_lineStartPressure => 'Pression initiale';
+
+  @override
+  String get gasCalculators_blender_lineEndPressure => 'Pression finale';
+
+  @override
+  String gasCalculators_blender_lineFillPressure(String pressure) {
+    return 'Pression de gonflage : $pressure';
+  }
+
+  @override
+  String gasCalculators_blender_lineComputedAmount(String amount) {
+    return 'Montant : $amount';
+  }
+
+  @override
+  String get gasCalculators_blender_lineNoPrice =>
+      'Aucun prix n\'est défini pour ce gaz, il est facturé à 0.';
+
+  @override
+  String get gasCalculators_blender_lineInvalidPressure =>
+      'La pression finale doit être supérieure à la pression initiale.';
+
+  @override
+  String get gasCalculators_blender_lineNeedsPressure =>
+      'Saisissez une pression initiale et une pression finale.';
+
+  @override
+  String get gasCalculators_blender_lineNeedsCylinder =>
+      'Saisissez un volume de bloc.';
+
+  @override
+  String get gasCalculators_blender_lineDescriptionOptional =>
+      'Facultatif. Laissé vide, il est généré à partir du gonflage.';
 
   @override
   String get gasCalculators_blender_export => 'Exporter';
diff --git a/lib/l10n/arb/app_localizations_he.dart b/lib/l10n/arb/app_localizations_he.dart
index 6a4149b432..f4e0c06340 100644
--- a/lib/l10n/arb/app_localizations_he.dart
+++ b/lib/l10n/arb/app_localizations_he.dart
@@ -13909,8 +13909,51 @@ class AppLocalizationsHe extends AppLocalizations {
   String get gasCalculators_blender_lineAmount => 'סכום';
 
   @override
-  String get gasCalculators_blender_lineNeedsDescription =>
-      'יש להזין תיאור, או מכל ותערובת.';
+  String get gasCalculators_blender_lineNeedsDescription => 'יש להזין תיאור.';
+
+  @override
+  String get gasCalculators_blender_lineKindGas => 'מילוי גז';
+
+  @override
+  String get gasCalculators_blender_lineKindAmount => 'סכום חופשי';
+
+  @override
+  String get gasCalculators_blender_lineGas => 'מילוי';
+
+  @override
+  String get gasCalculators_blender_lineStartPressure => 'לחץ התחלתי';
+
+  @override
+  String get gasCalculators_blender_lineEndPressure => 'לחץ סופי';
+
+  @override
+  String gasCalculators_blender_lineFillPressure(String pressure) {
+    return 'לחץ מילוי: $pressure';
+  }
+
+  @override
+  String gasCalculators_blender_lineComputedAmount(String amount) {
+    return 'סכום: $amount';
+  }
+
+  @override
+  String get gasCalculators_blender_lineNoPrice =>
+      'לא הוגדר מחיר לגז זה, ולכן הוא מחויב ב-0.';
+
+  @override
+  String get gasCalculators_blender_lineInvalidPressure =>
+      'הלחץ הסופי חייב להיות גבוה מהלחץ ההתחלתי.';
+
+  @override
+  String get gasCalculators_blender_lineNeedsPressure =>
+      'יש להזין לחץ התחלתי ולחץ סופי.';
+
+  @override
+  String get gasCalculators_blender_lineNeedsCylinder => 'יש להזין נפח מכל.';
+
+  @override
+  String get gasCalculators_blender_lineDescriptionOptional =>
+      'אופציונלי. אם יישאר ריק, הוא ייווצר מתוך המילוי.';
 
   @override
   String get gasCalculators_blender_export => 'ייצוא';
diff --git a/lib/l10n/arb/app_localizations_hu.dart b/lib/l10n/arb/app_localizations_hu.dart
index affd8734a5..fd95e9550d 100644
--- a/lib/l10n/arb/app_localizations_hu.dart
+++ b/lib/l10n/arb/app_localizations_hu.dart
@@ -14201,7 +14201,52 @@ class AppLocalizationsHu extends AppLocalizations {
 
   @override
   String get gasCalculators_blender_lineNeedsDescription =>
-      'Adjon meg egy leírást, vagy egy palackot és keveréket.';
+      'Adjon meg egy leírást.';
+
+  @override
+  String get gasCalculators_blender_lineKindGas => 'Gáztöltés';
+
+  @override
+  String get gasCalculators_blender_lineKindAmount => 'Szabad összeg';
+
+  @override
+  String get gasCalculators_blender_lineGas => 'Töltés';
+
+  @override
+  String get gasCalculators_blender_lineStartPressure => 'Kezdőnyomás';
+
+  @override
+  String get gasCalculators_blender_lineEndPressure => 'Végnyomás';
+
+  @override
+  String gasCalculators_blender_lineFillPressure(String pressure) {
+    return 'Töltési nyomás: $pressure';
+  }
+
+  @override
+  String gasCalculators_blender_lineComputedAmount(String amount) {
+    return 'Összeg: $amount';
+  }
+
+  @override
+  String get gasCalculators_blender_lineNoPrice =>
+      'Ehhez a gázhoz nincs ár megadva, ezért 0-val számolunk.';
+
+  @override
+  String get gasCalculators_blender_lineInvalidPressure =>
+      'A végnyomásnak nagyobbnak kell lennie a kezdőnyomásnál.';
+
+  @override
+  String get gasCalculators_blender_lineNeedsPressure =>
+      'Adjon meg egy kezdő- és egy végnyomást.';
+
+  @override
+  String get gasCalculators_blender_lineNeedsCylinder =>
+      'Adja meg a palack térfogatát.';
+
+  @override
+  String get gasCalculators_blender_lineDescriptionOptional =>
+      'Nem kötelező. Ha üresen marad, a töltésből jön létre.';
 
   @override
   String get gasCalculators_blender_export => 'Exportálás';
diff --git a/lib/l10n/arb/app_localizations_it.dart b/lib/l10n/arb/app_localizations_it.dart
index 64b177e8f7..eaf1b5dcf2 100644
--- a/lib/l10n/arb/app_localizations_it.dart
+++ b/lib/l10n/arb/app_localizations_it.dart
@@ -14248,7 +14248,52 @@ class AppLocalizationsIt extends AppLocalizations {
 
   @override
   String get gasCalculators_blender_lineNeedsDescription =>
-      'Inserisci una descrizione, oppure una bombola e una miscela.';
+      'Inserisci una descrizione.';
+
+  @override
+  String get gasCalculators_blender_lineKindGas => 'Ricarica di gas';
+
+  @override
+  String get gasCalculators_blender_lineKindAmount => 'Importo libero';
+
+  @override
+  String get gasCalculators_blender_lineGas => 'Ricarica';
+
+  @override
+  String get gasCalculators_blender_lineStartPressure => 'Pressione iniziale';
+
+  @override
+  String get gasCalculators_blender_lineEndPressure => 'Pressione finale';
+
+  @override
+  String gasCalculators_blender_lineFillPressure(String pressure) {
+    return 'Pressione di ricarica: $pressure';
+  }
+
+  @override
+  String gasCalculators_blender_lineComputedAmount(String amount) {
+    return 'Importo: $amount';
+  }
+
+  @override
+  String get gasCalculators_blender_lineNoPrice =>
+      'Nessun prezzo impostato per questo gas, quindi viene addebitato a 0.';
+
+  @override
+  String get gasCalculators_blender_lineInvalidPressure =>
+      'La pressione finale deve essere superiore a quella iniziale.';
+
+  @override
+  String get gasCalculators_blender_lineNeedsPressure =>
+      'Inserisci una pressione iniziale e una finale.';
+
+  @override
+  String get gasCalculators_blender_lineNeedsCylinder =>
+      'Inserisci un volume della bombola.';
+
+  @override
+  String get gasCalculators_blender_lineDescriptionOptional =>
+      'Facoltativo. Se lasciato vuoto, viene generato dalla ricarica.';
 
   @override
   String get gasCalculators_blender_export => 'Esporta';
diff --git a/lib/l10n/arb/app_localizations_nl.dart b/lib/l10n/arb/app_localizations_nl.dart
index 7005f70da5..05617cb8d6 100644
--- a/lib/l10n/arb/app_localizations_nl.dart
+++ b/lib/l10n/arb/app_localizations_nl.dart
@@ -14138,7 +14138,52 @@ class AppLocalizationsNl extends AppLocalizations {
 
   @override
   String get gasCalculators_blender_lineNeedsDescription =>
-      'Voer een omschrijving in, of een fles en mengsel.';
+      'Voer een omschrijving in.';
+
+  @override
+  String get gasCalculators_blender_lineKindGas => 'Gasvulling';
+
+  @override
+  String get gasCalculators_blender_lineKindAmount => 'Vrij bedrag';
+
+  @override
+  String get gasCalculators_blender_lineGas => 'Vulling';
+
+  @override
+  String get gasCalculators_blender_lineStartPressure => 'Begindruk';
+
+  @override
+  String get gasCalculators_blender_lineEndPressure => 'Einddruk';
+
+  @override
+  String gasCalculators_blender_lineFillPressure(String pressure) {
+    return 'Vuldruk: $pressure';
+  }
+
+  @override
+  String gasCalculators_blender_lineComputedAmount(String amount) {
+    return 'Bedrag: $amount';
+  }
+
+  @override
+  String get gasCalculators_blender_lineNoPrice =>
+      'Voor dit gas is geen prijs ingesteld, dus het wordt tegen 0 berekend.';
+
+  @override
+  String get gasCalculators_blender_lineInvalidPressure =>
+      'De einddruk moet boven de begindruk liggen.';
+
+  @override
+  String get gasCalculators_blender_lineNeedsPressure =>
+      'Voer een begin- en een einddruk in.';
+
+  @override
+  String get gasCalculators_blender_lineNeedsCylinder =>
+      'Voer een flesinhoud in.';
+
+  @override
+  String get gasCalculators_blender_lineDescriptionOptional =>
+      'Optioneel. Leeg gelaten wordt het uit de vulling gemaakt.';
 
   @override
   String get gasCalculators_blender_export => 'Exporteren';
diff --git a/lib/l10n/arb/app_localizations_pt.dart b/lib/l10n/arb/app_localizations_pt.dart
index 97f34c1974..51f5f78114 100644
--- a/lib/l10n/arb/app_localizations_pt.dart
+++ b/lib/l10n/arb/app_localizations_pt.dart
@@ -14245,7 +14245,52 @@ class AppLocalizationsPt extends AppLocalizations {
 
   @override
   String get gasCalculators_blender_lineNeedsDescription =>
-      'Introduza uma descrição, ou um cilindro e uma mistura.';
+      'Introduza uma descrição.';
+
+  @override
+  String get gasCalculators_blender_lineKindGas => 'Enchimento de gás';
+
+  @override
+  String get gasCalculators_blender_lineKindAmount => 'Valor livre';
+
+  @override
+  String get gasCalculators_blender_lineGas => 'Enchimento';
+
+  @override
+  String get gasCalculators_blender_lineStartPressure => 'Pressão inicial';
+
+  @override
+  String get gasCalculators_blender_lineEndPressure => 'Pressão final';
+
+  @override
+  String gasCalculators_blender_lineFillPressure(String pressure) {
+    return 'Pressão de enchimento: $pressure';
+  }
+
+  @override
+  String gasCalculators_blender_lineComputedAmount(String amount) {
+    return 'Valor: $amount';
+  }
+
+  @override
+  String get gasCalculators_blender_lineNoPrice =>
+      'Não há preço definido para este gás, por isso é cobrado a 0.';
+
+  @override
+  String get gasCalculators_blender_lineInvalidPressure =>
+      'A pressão final tem de ser superior à pressão inicial.';
+
+  @override
+  String get gasCalculators_blender_lineNeedsPressure =>
+      'Introduza uma pressão inicial e uma final.';
+
+  @override
+  String get gasCalculators_blender_lineNeedsCylinder =>
+      'Introduza um volume de cilindro.';
+
+  @override
+  String get gasCalculators_blender_lineDescriptionOptional =>
+      'Opcional. Se ficar vazio, é gerado a partir do enchimento.';
 
   @override
   String get gasCalculators_blender_export => 'Exportar';
diff --git a/lib/l10n/arb/app_localizations_zh.dart b/lib/l10n/arb/app_localizations_zh.dart
index 80b6de6611..df713bf06a 100644
--- a/lib/l10n/arb/app_localizations_zh.dart
+++ b/lib/l10n/arb/app_localizations_zh.dart
@@ -13567,7 +13567,48 @@ class AppLocalizationsZh extends AppLocalizations {
   String get gasCalculators_blender_lineAmount => '金额';
 
   @override
-  String get gasCalculators_blender_lineNeedsDescription => '请输入说明，或气瓶与混合气。';
+  String get gasCalculators_blender_lineNeedsDescription => '请输入说明。';
+
+  @override
+  String get gasCalculators_blender_lineKindGas => '气体充填';
+
+  @override
+  String get gasCalculators_blender_lineKindAmount => '自由金额';
+
+  @override
+  String get gasCalculators_blender_lineGas => '充填';
+
+  @override
+  String get gasCalculators_blender_lineStartPressure => '初始压力';
+
+  @override
+  String get gasCalculators_blender_lineEndPressure => '最终压力';
+
+  @override
+  String gasCalculators_blender_lineFillPressure(String pressure) {
+    return '充填压力：$pressure';
+  }
+
+  @override
+  String gasCalculators_blender_lineComputedAmount(String amount) {
+    return '金额：$amount';
+  }
+
+  @override
+  String get gasCalculators_blender_lineNoPrice => '此气体未设置价格，按 0 计费。';
+
+  @override
+  String get gasCalculators_blender_lineInvalidPressure => '最终压力必须高于初始压力。';
+
+  @override
+  String get gasCalculators_blender_lineNeedsPressure => '请输入初始压力和最终压力。';
+
+  @override
+  String get gasCalculators_blender_lineNeedsCylinder => '请输入气瓶容积。';
+
+  @override
+  String get gasCalculators_blender_lineDescriptionOptional =>
+      '可选。留空时根据充填自动生成。';
 
   @override
   String get gasCalculators_blender_export => '导出';
diff --git a/lib/l10n/arb/app_nl.arb b/lib/l10n/arb/app_nl.arb
index 8c362fe224..cc13d46e84 100644
--- a/lib/l10n/arb/app_nl.arb
+++ b/lib/l10n/arb/app_nl.arb
@@ -142,7 +142,19 @@
   "gasCalculators_blender_addManualLine": "Regel toevoegen",
   "gasCalculators_blender_lineDescription": "Omschrijving",
   "gasCalculators_blender_lineAmount": "Bedrag",
-  "gasCalculators_blender_lineNeedsDescription": "Voer een omschrijving in, of een fles en mengsel.",
+  "gasCalculators_blender_lineNeedsDescription": "Voer een omschrijving in.",
+  "gasCalculators_blender_lineKindGas": "Gasvulling",
+  "gasCalculators_blender_lineKindAmount": "Vrij bedrag",
+  "gasCalculators_blender_lineGas": "Vulling",
+  "gasCalculators_blender_lineStartPressure": "Begindruk",
+  "gasCalculators_blender_lineEndPressure": "Einddruk",
+  "gasCalculators_blender_lineFillPressure": "Vuldruk: {pressure}",
+  "gasCalculators_blender_lineComputedAmount": "Bedrag: {amount}",
+  "gasCalculators_blender_lineNoPrice": "Voor dit gas is geen prijs ingesteld, dus het wordt tegen 0 berekend.",
+  "gasCalculators_blender_lineInvalidPressure": "De einddruk moet boven de begindruk liggen.",
+  "gasCalculators_blender_lineNeedsPressure": "Voer een begin- en een einddruk in.",
+  "gasCalculators_blender_lineNeedsCylinder": "Voer een flesinhoud in.",
+  "gasCalculators_blender_lineDescriptionOptional": "Optioneel. Leeg gelaten wordt het uit de vulling gemaakt.",
   "gasCalculators_blender_export": "Exporteren",
   "gasCalculators_blender_exportPdf": "Exporteren als PDF",
   "gasCalculators_blender_exportImage": "Exporteren als afbeelding",
diff --git a/lib/l10n/arb/app_pt.arb b/lib/l10n/arb/app_pt.arb
index 1bc61ad99b..5b38c47aeb 100644
--- a/lib/l10n/arb/app_pt.arb
+++ b/lib/l10n/arb/app_pt.arb
@@ -142,7 +142,19 @@
   "gasCalculators_blender_addManualLine": "Adicionar uma linha",
   "gasCalculators_blender_lineDescription": "Descrição",
   "gasCalculators_blender_lineAmount": "Valor",
-  "gasCalculators_blender_lineNeedsDescription": "Introduza uma descrição, ou um cilindro e uma mistura.",
+  "gasCalculators_blender_lineNeedsDescription": "Introduza uma descrição.",
+  "gasCalculators_blender_lineKindGas": "Enchimento de gás",
+  "gasCalculators_blender_lineKindAmount": "Valor livre",
+  "gasCalculators_blender_lineGas": "Enchimento",
+  "gasCalculators_blender_lineStartPressure": "Pressão inicial",
+  "gasCalculators_blender_lineEndPressure": "Pressão final",
+  "gasCalculators_blender_lineFillPressure": "Pressão de enchimento: {pressure}",
+  "gasCalculators_blender_lineComputedAmount": "Valor: {amount}",
+  "gasCalculators_blender_lineNoPrice": "Não há preço definido para este gás, por isso é cobrado a 0.",
+  "gasCalculators_blender_lineInvalidPressure": "A pressão final tem de ser superior à pressão inicial.",
+  "gasCalculators_blender_lineNeedsPressure": "Introduza uma pressão inicial e uma final.",
+  "gasCalculators_blender_lineNeedsCylinder": "Introduza um volume de cilindro.",
+  "gasCalculators_blender_lineDescriptionOptional": "Opcional. Se ficar vazio, é gerado a partir do enchimento.",
   "gasCalculators_blender_export": "Exportar",
   "gasCalculators_blender_exportPdf": "Exportar como PDF",
   "gasCalculators_blender_exportImage": "Exportar como imagem",
diff --git a/lib/l10n/arb/app_zh.arb b/lib/l10n/arb/app_zh.arb
index 186a45f2f7..81f6e73a69 100644
--- a/lib/l10n/arb/app_zh.arb
+++ b/lib/l10n/arb/app_zh.arb
@@ -142,7 +142,19 @@
   "gasCalculators_blender_addManualLine": "添加条目",
   "gasCalculators_blender_lineDescription": "说明",
   "gasCalculators_blender_lineAmount": "金额",
-  "gasCalculators_blender_lineNeedsDescription": "请输入说明，或气瓶与混合气。",
+  "gasCalculators_blender_lineNeedsDescription": "请输入说明。",
+  "gasCalculators_blender_lineKindGas": "气体充填",
+  "gasCalculators_blender_lineKindAmount": "自由金额",
+  "gasCalculators_blender_lineGas": "充填",
+  "gasCalculators_blender_lineStartPressure": "初始压力",
+  "gasCalculators_blender_lineEndPressure": "最终压力",
+  "gasCalculators_blender_lineFillPressure": "充填压力：{pressure}",
+  "gasCalculators_blender_lineComputedAmount": "金额：{amount}",
+  "gasCalculators_blender_lineNoPrice": "此气体未设置价格，按 0 计费。",
+  "gasCalculators_blender_lineInvalidPressure": "最终压力必须高于初始压力。",
+  "gasCalculators_blender_lineNeedsPressure": "请输入初始压力和最终压力。",
+  "gasCalculators_blender_lineNeedsCylinder": "请输入气瓶容积。",
+  "gasCalculators_blender_lineDescriptionOptional": "可选。留空时根据充填自动生成。",
   "gasCalculators_blender_export": "导出",
   "gasCalculators_blender_exportPdf": "导出为 PDF",
   "gasCalculators_blender_exportImage": "导出为图片",
diff --git a/test/features/gas_calculators/blender_invoice_test.dart b/test/features/gas_calculators/blender_invoice_test.dart
index 09c2ab6195..bce80fb92f 100644
--- a/test/features/gas_calculators/blender_invoice_test.dart
+++ b/test/features/gas_calculators/blender_invoice_test.dart
@@ -4,13 +4,17 @@ import 'dart:io';
 import 'package:excel_community/excel_community.dart' as xl;
 import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
+import 'package:intl/intl.dart';
 import 'package:path_provider_platform_interface/path_provider_platform_interface.dart';
 import 'package:plugin_platform_interface/plugin_platform_interface.dart';
 import 'package:share_plus_platform_interface/share_plus_platform_interface.dart';
+import 'package:submersion/core/constants/enums.dart';
+import 'package:submersion/core/constants/units.dart';
 import 'package:submersion/core/providers/provider.dart';
 import 'package:submersion/features/dive_log/domain/entities/dive.dart'
     show GasMix;
 import 'package:submersion/features/gas_calculators/domain/blending/billed_fill.dart';
+import 'package:submersion/features/gas_calculators/domain/blending/blender_gas_role.dart';
 import 'package:submersion/features/gas_calculators/domain/blending/blender_preferences.dart';
 import 'package:submersion/features/gas_calculators/domain/blending/flush_fee.dart';
 import 'package:submersion/features/gas_calculators/presentation/providers/gas_blender_providers.dart';
@@ -18,6 +22,7 @@ import 'package:submersion/features/gas_calculators/presentation/widgets/blender
 import 'package:submersion/features/gas_calculators/presentation/widgets/blender/blender_invoice_card.dart';
 import 'package:submersion/features/gas_calculators/presentation/widgets/blender/blender_invoice_export_sheet.dart';
 import 'package:submersion/features/settings/presentation/providers/settings_providers.dart';
+import 'package:submersion/features/tank_presets/domain/entities/tank_preset_entity.dart';
 import 'package:submersion/features/tank_presets/presentation/providers/tank_preset_providers.dart';
 import 'package:submersion/l10n/arb/app_localizations.dart';
 
@@ -50,18 +55,40 @@ class _TestSettingsNotifier extends StateNotifier<AppSettings>
   dynamic noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
 }
 
-Future<WidgetRef> _pump(WidgetTester tester) async {
+/// Opens "Add a line", switched to the free-amount kind when [freeAmount].
+Future<void> _openAddLine(
+  WidgetTester tester, {
+  bool freeAmount = false,
+}) async {
+  await tester.tap(find.byKey(const Key('blender-add-manual-line')));
+  await tester.pumpAndSettle();
+  if (freeAmount) {
+    await tester.tap(find.text('Free amount'));
+    await tester.pumpAndSettle();
+  }
+}
+
+/// Picks [gas] from the gas fill's dropdown.
+Future<void> _pickGas(WidgetTester tester, String gas) async {
+  await tester.tap(find.byKey(const Key('blender-line-gas')));
+  await tester.pumpAndSettle();
+  await tester.tap(find.text(gas).last);
+  await tester.pumpAndSettle();
+}
+
+Future<WidgetRef> _pump(
+  WidgetTester tester, {
+  List<TankPresetEntity> presets = const [],
+  AppSettings settings = const AppSettings(defaultCurrency: 'CHF'),
+}) async {
   await tester.binding.setSurfaceSize(const Size(900, 2400));
   addTearDown(() => tester.binding.setSurfaceSize(null));
   late WidgetRef captured;
   await tester.pumpWidget(
     ProviderScope(
       overrides: [
-        settingsProvider.overrideWith(
-          (ref) =>
-              _TestSettingsNotifier(const AppSettings(defaultCurrency: 'CHF')),
-        ),
-        tankPresetsProvider.overrideWith((ref) async => const []),
+        settingsProvider.overrideWith((ref) => _TestSettingsNotifier(settings)),
+        tankPresetsProvider.overrideWith((ref) async => presets),
       ],
       child: MaterialApp(
         locale: const Locale('en'),
@@ -149,41 +176,89 @@ void main() {
       expect(fill.isManual, isTrue);
     });
 
-    test('a custom mix round-trips through JSON alongside the fill', () {
+    test('a hand-entered gas fill round-trips its role and start pressure '
+        '(#2302)', () {
       const fill = BilledFill(
         id: 'c',
-        label: 'Tx 21/35',
-        lines: [],
-        total: 40,
-        customMix: BilledCustomMix(cylinderLiters: 11.1, o2: 21, he: 35),
+        label: 'Helium',
+        lines: [
+          BilledGasLine(
+            gas: 'Helium',
+            addedBar: 150,
+            cost: 27,
+            freeGasLiters: 1800,
+            cylinderLiters: 12,
+            role: BlenderGasRole.he,
+            startBar: 50,
+          ),
+        ],
+        total: 27,
       );
       final decoded = BilledFill.fromJson(
         jsonDecode(jsonEncode(fill.toJson())) as Map<String, dynamic>,
       )!;
-      expect(decoded.customMix, isNotNull);
-      expect(decoded.customMix!.cylinderLiters, 11.1);
-      expect(decoded.customMix!.o2, 21);
-      expect(decoded.customMix!.he, 35);
+      final line = decoded.manualGasLine;
+      expect(line, isNotNull);
+      expect(line!.role, BlenderGasRole.he);
+      expect(line.startBar, 50);
+      expect(line.endBar, 200);
+      expect(decoded.isManual, isFalse);
     });
 
-    test('a fill without a custom mix decodes with none', () {
-      const fill = BilledFill(id: 'd', label: 'x', lines: [], total: 1);
-      final decoded = BilledFill.fromJson(
-        jsonDecode(jsonEncode(fill.toJson())) as Map<String, dynamic>,
-      )!;
-      expect(decoded.customMix, isNull);
+    test('a computed fill is not a hand-entered gas fill', () {
+      const fill = BilledFill(
+        id: 'd',
+        label: 'Tx 18/45',
+        lines: [BilledGasLine(gas: 'O₂', addedBar: 10, cost: 10)],
+        total: 10,
+      );
+      expect(fill.manualGasLine, isNull);
     });
 
-    test('copyWith can clear a custom mix', () {
+    test('an unknown role in a synced blob decodes to none, keeping the '
+        'line', () {
+      final line = BilledGasLine.fromJson({
+        'gas': 'X',
+        'addedBar': 10,
+        'role': 'argon',
+        'startBar': 'oops',
+      })!;
+      expect(line.role, isNull);
+      expect(line.startBar, isNull);
+      expect(line.addedBar, 10);
+    });
+
+    test('a manual line saved with the retired custom mix still decodes, '
+        'without it (#2302)', () {
+      final decoded = BilledFill.fromJson({
+        'id': 'e',
+        'label': 'Tx 21/35',
+        'lines': [],
+        'total': 40,
+        'customMix': {'cylinderLiters': 11.1, 'o2': 21, 'he': 35},
+      })!;
+      expect(decoded.label, 'Tx 21/35');
+      expect(decoded.total, 40);
+      expect(decoded.isManual, isTrue);
+      expect(decoded.toJson().containsKey('customMix'), isFalse);
+    });
+
+    test('copyWith can replace the lines, and leaves them alone otherwise', () {
       const fill = BilledFill(
-        id: 'e',
-        label: 'Tx 21/35',
-        lines: [],
-        total: 40,
-        customMix: BilledCustomMix(cylinderLiters: 11.1, o2: 21, he: 35),
+        id: 'f',
+        label: 'Helium',
+        lines: [
+          BilledGasLine(
+            gas: 'Helium',
+            addedBar: 150,
+            cost: 27,
+            role: BlenderGasRole.he,
+          ),
+        ],
+        total: 27,
       );
-      expect(fill.copyWith(label: 'x').customMix, isNotNull);
-      expect(fill.copyWith(clearCustomMix: true).customMix, isNull);
+      expect(fill.copyWith(label: 'x').lines, hasLength(1));
+      expect(fill.copyWith(lines: const []).isManual, isTrue);
     });
 
     test('an unpriced line makes the total incomplete, not smaller', () {
@@ -373,10 +448,9 @@ void main() {
       expect(ref.read(blenderBilledFillsProvider), isEmpty);
     });
 
-    testWidgets('a manual line can be added', (tester) async {
+    testWidgets('a free-amount line can be added', (tester) async {
       final ref = await _pump(tester);
-      await tester.tap(find.byKey(const Key('blender-add-manual-line')));
-      await tester.pumpAndSettle();
+      await _openAddLine(tester, freeAmount: true);
 
       await tester.enterText(
         find.byKey(const Key('blender-line-description')),
@@ -396,18 +470,13 @@ void main() {
       expect(fills.single.total, closeTo(12.50, 0.001));
     });
 
-    testWidgets('saving a line with nothing to name it says so', (
+    testWidgets('a free amount with nothing to name it says so', (
       tester,
     ) async {
-      // PR #1359 review: with no description and no usable mix there was
-      // nothing to label the line with, and Save simply returned - no line,
-      // no message, a button that reads as broken.
-      await _pump(tester);
-      await tester.tap(find.byKey(const Key('blender-add-manual-line')));
-      await tester.pumpAndSettle();
-      // The mix fields are pre-filled, so the label can fall back to them
-      // until one of them is cleared.
-      await tester.enterText(find.widgetWithText(TextField, 'O\u2082 (%)'), '');
+      // PR #1359 review: with nothing to label the line with, Save simply
+      // returned - no line, no message, a button that reads as broken.
+      final ref = await _pump(tester);
+      await _openAddLine(tester, freeAmount: true);
       await tester.enterText(
         find.byKey(const Key('blender-line-amount')),
         '12.50',
@@ -420,83 +489,753 @@ void main() {
       expect(find.textContaining('Enter a description'), findsOneWidget);
       // Still open, with the amount intact, so the diver can fix it in place.
       expect(find.byKey(const Key('blender-line-amount')), findsOneWidget);
+      expect(ref.read(blenderBilledFillsProvider), isEmpty);
     });
 
-    testWidgets('a custom mix line records the cylinder and gas entered', (
-      tester,
-    ) async {
-      final ref = await _pump(tester);
-      await tester.tap(find.byKey(const Key('blender-add-manual-line')));
+    testWidgets('the kind switch shows only the fields that kind needs '
+        '(#2302)', (tester) async {
+      await _pump(tester);
+      await _openAddLine(tester);
+
+      // A new line starts as a gas fill.
+      expect(find.byKey(const Key('blender-line-gas')), findsOneWidget);
+      expect(find.byKey(const Key('blender-line-cylinder')), findsOneWidget);
+      expect(
+        find.byKey(const Key('blender-line-start-pressure')),
+        findsOneWidget,
+      );
+      expect(
+        find.byKey(const Key('blender-line-end-pressure')),
+        findsOneWidget,
+      );
+      expect(
+        find.byKey(const Key('blender-line-computed-amount')),
+        findsOneWidget,
+      );
+      expect(find.byKey(const Key('blender-line-amount')), findsNothing);
+
+      await tester.tap(find.text('Free amount'));
       await tester.pumpAndSettle();
 
+      expect(find.byKey(const Key('blender-line-amount')), findsOneWidget);
+      expect(find.byKey(const Key('blender-line-gas')), findsNothing);
+      expect(find.byKey(const Key('blender-line-cylinder')), findsNothing);
+      expect(find.byKey(const Key('blender-line-end-pressure')), findsNothing);
+      expect(
+        find.byKey(const Key('blender-line-computed-amount')),
+        findsNothing,
+      );
+    });
+
+    testWidgets('a gas fill is priced from the cylinder, the pressures and '
+        'the gas price (#2302)', (tester) async {
+      final ref = await _pump(tester);
+      ref.read(blenderGasPricesProvider.notifier).state = const [1.0, 1.5, 0.1];
+      await _openAddLine(tester);
+
+      await _pickGas(tester, 'Helium');
       await tester.enterText(
         find.byKey(const Key('blender-line-cylinder')),
-        '11.1',
+        '12',
       );
       await tester.enterText(
-        find.byKey(const Key('blender-line-amount')),
+        find.byKey(const Key('blender-line-start-pressure')),
+        '50',
+      );
+      await tester.enterText(
+        find.byKey(const Key('blender-line-end-pressure')),
+        '200',
+      );
+      await tester.pumpAndSettle();
+
+      // Shown live, as text rather than an editable field.
+      expect(
+        tester
+            .widget<Text>(find.byKey(const Key('blender-line-fill-pressure')))
+            .data,
+        contains('150'),
+      );
+      expect(
+        tester
+            .widget<Text>(find.byKey(const Key('blender-line-computed-amount')))
+            .data,
+        contains('27.00'),
+      );
+      expect(find.byKey(const Key('blender-line-no-price')), findsNothing);
+
+      await tester.tap(find.widgetWithText(FilledButton, 'Save'));
+      await tester.pumpAndSettle();
+
+      final fills = ref.read(blenderBilledFillsProvider);
+      expect(fills, hasLength(1));
+      expect(fills.single.total, closeTo(27, 1e-9));
+      final line = fills.single.manualGasLine!;
+      expect(line.role, BlenderGasRole.he);
+      expect(line.gas, 'Helium');
+      expect(line.addedBar, 150);
+      expect(line.startBar, 50);
+      expect(line.freeGasLiters, 1800);
+      expect(line.cylinderLiters, 12);
+      // No description typed: the label is generated from the fill.
+      expect(fills.single.label, startsWith('Helium · 12'));
+      expect(fills.single.label, endsWith('150.0 bar'));
+    });
+
+    testWidgets('a gas without a price is charged at 0, and the form says '
+        'so (#2302)', (tester) async {
+      final ref = await _pump(tester);
+      await _openAddLine(tester);
+
+      expect(find.byKey(const Key('blender-line-no-price')), findsOneWidget);
+
+      await tester.tap(find.widgetWithText(FilledButton, 'Save'));
+      await tester.pumpAndSettle();
+
+      final fills = ref.read(blenderBilledFillsProvider);
+      expect(fills, hasLength(1));
+      expect(fills.single.total, 0);
+      // Priced at zero, so the bill is complete rather than flagged.
+      expect(totalOf(fills).complete, isTrue);
+    });
+
+    testWidgets('an end pressure not above the start pressure blocks saving '
+        '(#2302)', (tester) async {
+      final ref = await _pump(tester);
+      await _openAddLine(tester);
+
+      await tester.enterText(
+        find.byKey(const Key('blender-line-start-pressure')),
+        '200',
+      );
+      await tester.enterText(
+        find.byKey(const Key('blender-line-end-pressure')),
+        '100',
+      );
+      await tester.pumpAndSettle();
+      await tester.tap(find.widgetWithText(FilledButton, 'Save'));
+      await tester.pumpAndSettle();
+
+      expect(find.textContaining('end pressure must be above'), findsOneWidget);
+      expect(ref.read(blenderBilledFillsProvider), isEmpty);
+    });
+
+    testWidgets('a cylinder preset sets the volume and the end pressure, '
+        'which stays editable (#2302)', (tester) async {
+      final ref = await _pump(
+        tester,
+        presets: [
+          TankPresetEntity(
+            id: 'd12',
+            name: 'd12',
+            displayName: 'D12 232',
+            volumeLiters: 12,
+            workingPressureBar: 232,
+            material: TankMaterial.steel,
+            createdAt: DateTime(2024),
+            updatedAt: DateTime(2024),
+          ),
+        ],
+      );
+      ref.read(blenderGasPricesProvider.notifier).state = const [1.0, 1.5, 0.1];
+      await _openAddLine(tester);
+
+      await tester.tap(find.byKey(const Key('blender-line-cylinder-presets')));
+      await tester.pumpAndSettle();
+      await tester.tap(find.textContaining('D12 232').last);
+      await tester.pumpAndSettle();
+
+      String text(String key) =>
+          tester.widget<TextField>(find.byKey(Key(key))).controller!.text;
+      expect(text('blender-line-cylinder'), '12');
+      expect(text('blender-line-end-pressure'), '232');
+
+      // Overridden by hand, e.g. for the oxygen step of a blend.
+      await tester.enterText(
+        find.byKey(const Key('blender-line-end-pressure')),
         '30',
       );
-      // Description left blank on purpose: the label falls back to the mix.
-      await tester.enterText(find.widgetWithText(TextField, 'O₂ (%)'), '21');
-      await tester.enterText(find.widgetWithText(TextField, 'He (%)'), '35');
+      await tester.pumpAndSettle();
+      await tester.tap(find.widgetWithText(FilledButton, 'Save'));
+      await tester.pumpAndSettle();
+
+      final line = ref.read(blenderBilledFillsProvider).single.manualGasLine!;
+      expect(line.role, BlenderGasRole.o2);
+      expect(line.addedBar, 30);
+      expect(line.cylinderLiters, 12);
+    });
+
+    testWidgets('re-editing a gas fill reopens it with its values and '
+        'reprices it (#2302)', (tester) async {
+      final ref = await _pump(tester);
+      ref.read(blenderGasPricesProvider.notifier).state = const [1.0, 1.5, 0.1];
+      ref.read(blenderBilledFillsProvider.notifier).state = const [
+        BilledFill(
+          id: 'a',
+          label: 'Twinset',
+          lines: [
+            BilledGasLine(
+              gas: 'Helium',
+              addedBar: 150,
+              cost: 27,
+              freeGasLiters: 1800,
+              cylinderLiters: 12,
+              role: BlenderGasRole.he,
+              startBar: 50,
+            ),
+          ],
+          total: 27,
+        ),
+      ];
+      await tester.pumpAndSettle();
+
+      await tester.tap(find.byTooltip('Actions for Twinset'));
+      await tester.pumpAndSettle();
+      await tester.tap(find.text('Edit Twinset'));
+      await tester.pumpAndSettle();
+
+      String text(String key) =>
+          tester.widget<TextField>(find.byKey(Key(key))).controller!.text;
+      expect(text('blender-line-description'), 'Twinset');
+      expect(text('blender-line-cylinder'), '12');
+      expect(text('blender-line-start-pressure'), '50');
+      expect(text('blender-line-end-pressure'), '200');
+
+      await tester.enterText(
+        find.byKey(const Key('blender-line-end-pressure')),
+        '150',
+      );
       await tester.pumpAndSettle();
       await tester.tap(find.widgetWithText(FilledButton, 'Save'));
       await tester.pumpAndSettle();
 
       final fills = ref.read(blenderBilledFillsProvider);
       expect(fills, hasLength(1));
-      expect(fills.single.label, 'Tx 21/35');
-      expect(fills.single.customMix, isNotNull);
-      expect(fills.single.customMix!.cylinderLiters, closeTo(11.1, 0.001));
-      expect(fills.single.customMix!.o2, 21);
-      expect(fills.single.customMix!.he, 35);
+      expect(fills.single.label, 'Twinset');
+      expect(fills.single.manualGasLine!.addedBar, 100);
+      expect(fills.single.total, closeTo(18, 1e-9));
     });
 
-    testWidgets('re-editing a manual line pre-fills its saved mix', (
-      tester,
-    ) async {
+    testWidgets('pressures are entered in the diver\'s unit and stored in '
+        'bar (#2302)', (tester) async {
+      final ref = await _pump(
+        tester,
+        settings: const AppSettings(
+          defaultCurrency: 'CHF',
+          pressureUnit: PressureUnit.psi,
+        ),
+      );
+      ref.read(blenderGasPricesProvider.notifier).state = const [1.0, 1.5, 0.1];
+      await _openAddLine(tester);
+
+      expect(find.textContaining('Start pressure (psi)'), findsOneWidget);
+      await tester.enterText(
+        find.byKey(const Key('blender-line-cylinder')),
+        '10',
+      );
+      await tester.enterText(
+        find.byKey(const Key('blender-line-start-pressure')),
+        '0',
+      );
+      await tester.enterText(
+        find.byKey(const Key('blender-line-end-pressure')),
+        '3000',
+      );
+      await tester.pumpAndSettle();
+      await tester.tap(find.widgetWithText(FilledButton, 'Save'));
+      await tester.pumpAndSettle();
+
+      final fill = ref.read(blenderBilledFillsProvider).single;
+      const bar = 3000 / 14.5038;
+      expect(fill.manualGasLine!.addedBar, closeTo(bar, 0.01));
+      expect(fill.total, closeTo(10 * bar / 100, 0.01));
+      expect(fill.label, endsWith('psi'));
+    });
+
+    testWidgets('reopening a gas fill to change only its description keeps '
+        'what it was billed at (#2302 review)', (tester) async {
       final ref = await _pump(tester);
+      // Priced since at a rate that would make this line 41.85.
+      ref.read(blenderGasPricesProvider.notifier).state = const [1.0, 1.5, 0.1];
       ref.read(blenderBilledFillsProvider.notifier).state = const [
         BilledFill(
           id: 'a',
-          label: 'Tx 21/35',
-          lines: [],
-          total: 30,
-          customMix: BilledCustomMix(cylinderLiters: 11.1, o2: 21, he: 35),
+          label: 'Twinset',
+          lines: [
+            BilledGasLine(
+              gas: 'Helium',
+              addedBar: 232.5,
+              cost: 27,
+              freeGasLiters: 2790,
+              cylinderLiters: 12,
+              role: BlenderGasRole.he,
+              startBar: 0,
+            ),
+          ],
+          total: 27,
         ),
       ];
       await tester.pumpAndSettle();
 
-      await tester.tap(find.byTooltip('Actions for Tx 21/35'));
+      await tester.tap(find.byTooltip('Actions for Twinset'));
       await tester.pumpAndSettle();
-      await tester.tap(find.text('Edit Tx 21/35'));
+      await tester.tap(find.text('Edit Twinset'));
       await tester.pumpAndSettle();
 
-      final o2Field = tester.widget<TextField>(
-        find.widgetWithText(TextField, 'O₂ (%)'),
+      // Not rounded to a whole number, so an untouched save cannot move it.
+      expect(
+        tester
+            .widget<TextField>(
+              find.byKey(const Key('blender-line-end-pressure')),
+            )
+            .controller!
+            .text,
+        '232.5',
       );
-      expect(o2Field.controller!.text, '21');
-      final heField = tester.widget<TextField>(
-        find.widgetWithText(TextField, 'He (%)'),
+      expect(
+        tester
+            .widget<Text>(find.byKey(const Key('blender-line-computed-amount')))
+            .data,
+        contains('27.00'),
       );
-      expect(heField.controller!.text, '35');
 
-      // Changing the mix and saving updates the stored fill rather than
-      // adding a second one.
-      await tester.enterText(find.widgetWithText(TextField, 'He (%)'), '45');
+      await tester.enterText(
+        find.byKey(const Key('blender-line-description')),
+        'Doubles',
+      );
       await tester.pumpAndSettle();
       await tester.tap(find.widgetWithText(FilledButton, 'Save'));
       await tester.pumpAndSettle();
 
-      final fills = ref.read(blenderBilledFillsProvider);
-      expect(fills, hasLength(1));
-      expect(fills.single.customMix!.he, 45);
+      final fill = ref.read(blenderBilledFillsProvider).single;
+      expect(fill.label, 'Doubles');
+      expect(fill.total, 27);
+      expect(fill.manualGasLine!.addedBar, 232.5);
+      expect(fill.manualGasLine!.cost, 27);
+    });
+
+    testWidgets('switching a gas fill to a free amount starts from what it '
+        'cost (#2302 review)', (tester) async {
+      final ref = await _pump(tester);
+      ref.read(blenderBilledFillsProvider.notifier).state = const [
+        BilledFill(
+          id: 'a',
+          label: 'Twinset',
+          lines: [
+            BilledGasLine(
+              gas: 'Helium',
+              addedBar: 150,
+              cost: 27,
+              cylinderLiters: 12,
+              role: BlenderGasRole.he,
+              startBar: 50,
+            ),
+          ],
+          total: 27,
+        ),
+      ];
+      await tester.pumpAndSettle();
+
+      await tester.tap(find.byTooltip('Actions for Twinset'));
+      await tester.pumpAndSettle();
+      await tester.tap(find.text('Edit Twinset'));
+      await tester.pumpAndSettle();
+      await tester.tap(find.text('Free amount'));
+      await tester.pumpAndSettle();
+
+      expect(
+        tester
+            .widget<TextField>(find.byKey(const Key('blender-line-amount')))
+            .controller!
+            .text,
+        '27',
+      );
+      await tester.tap(find.widgetWithText(FilledButton, 'Save'));
+      await tester.pumpAndSettle();
+
+      final fill = ref.read(blenderBilledFillsProvider).single;
+      expect(fill.isManual, isTrue);
+      expect(fill.total, 27);
     });
 
-    testWidgets('a computed fill offers no mix fields when re-edited', (
+    testWidgets('an empty pressure asks for one rather than blaming the '
+        'order (#2302 review)', (tester) async {
+      final ref = await _pump(tester);
+      await _openAddLine(tester);
+
+      await tester.enterText(
+        find.byKey(const Key('blender-line-start-pressure')),
+        '',
+      );
+      await tester.pumpAndSettle();
+      await tester.tap(find.widgetWithText(FilledButton, 'Save'));
+      await tester.pumpAndSettle();
+
+      expect(
+        find.textContaining('Enter a start and an end pressure'),
+        findsOneWidget,
+      );
+      expect(ref.read(blenderBilledFillsProvider), isEmpty);
+    });
+
+    testWidgets('a preset picked in cubic feet bills its exact water volume '
+        '(#2302 review)', (tester) async {
+      final ref = await _pump(
+        tester,
+        settings: const AppSettings(
+          defaultCurrency: 'CHF',
+          volumeUnit: VolumeUnit.cubicFeet,
+        ),
+        presets: [
+          TankPresetEntity(
+            id: 'al80',
+            name: 'al80',
+            displayName: 'AL80',
+            volumeLiters: 11.1,
+            workingPressureBar: 207,
+            material: TankMaterial.aluminum,
+            createdAt: DateTime(2024),
+            updatedAt: DateTime(2024),
+          ),
+        ],
+      );
+      await _openAddLine(tester);
+
+      await tester.tap(find.byKey(const Key('blender-line-cylinder-presets')));
+      await tester.pumpAndSettle();
+      await tester.tap(find.textContaining('AL80').last);
+      await tester.pumpAndSettle();
+      await tester.tap(find.widgetWithText(FilledButton, 'Save'));
+      await tester.pumpAndSettle();
+
+      final line = ref.read(blenderBilledFillsProvider).single.manualGasLine!;
+      expect(line.cylinderLiters, 11.1);
+      expect(line.addedBar, 207);
+    });
+
+    testWidgets('a generated label saved in bar still regenerates once the '
+        'diver has switched to psi (#2302 review)', (tester) async {
+      final ref = await _pump(
+        tester,
+        settings: const AppSettings(
+          defaultCurrency: 'CHF',
+          pressureUnit: PressureUnit.psi,
+        ),
+      );
+      ref.read(blenderBilledFillsProvider.notifier).state = const [
+        BilledFill(
+          id: 'a',
+          label: 'Helium · 12 L · 150.0 bar',
+          lines: [
+            BilledGasLine(
+              gas: 'Helium',
+              addedBar: 150,
+              cost: 0,
+              cylinderLiters: 12,
+              role: BlenderGasRole.he,
+              startBar: 0,
+            ),
+          ],
+          total: 0,
+        ),
+      ];
+      await tester.pumpAndSettle();
+
+      await tester.tap(find.byTooltip('Actions for Helium · 12 L · 150.0 bar'));
+      await tester.pumpAndSettle();
+      await tester.tap(find.text('Edit Helium · 12 L · 150.0 bar'));
+      await tester.pumpAndSettle();
+
+      expect(
+        tester
+            .widget<TextField>(
+              find.byKey(const Key('blender-line-description')),
+            )
+            .controller!
+            .text,
+        isEmpty,
+      );
+      await tester.enterText(
+        find.byKey(const Key('blender-line-end-pressure')),
+        '1000',
+      );
+      await tester.pumpAndSettle();
+      await tester.tap(find.widgetWithText(FilledButton, 'Save'));
+      await tester.pumpAndSettle();
+
+      expect(
+        ref.read(blenderBilledFillsProvider).single.label,
+        endsWith('1000 psi'),
+      );
+    });
+
+    testWidgets('switching a gas fill with a generated label to a free '
+        'amount keeps its label (#2302 review)', (tester) async {
+      final ref = await _pump(tester);
+      ref.read(blenderBilledFillsProvider.notifier).state = const [
+        BilledFill(
+          id: 'a',
+          label: 'Helium · 12 L · 150.0 bar',
+          lines: [
+            BilledGasLine(
+              gas: 'Helium',
+              addedBar: 150,
+              cost: 27,
+              cylinderLiters: 12,
+              role: BlenderGasRole.he,
+              startBar: 0,
+            ),
+          ],
+          total: 27,
+        ),
+      ];
+      await tester.pumpAndSettle();
+
+      await tester.tap(find.byTooltip('Actions for Helium · 12 L · 150.0 bar'));
+      await tester.pumpAndSettle();
+      await tester.tap(find.text('Edit Helium · 12 L · 150.0 bar'));
+      await tester.pumpAndSettle();
+      await tester.tap(find.text('Free amount'));
+      await tester.pumpAndSettle();
+      await tester.tap(find.widgetWithText(FilledButton, 'Save'));
+      await tester.pumpAndSettle();
+
+      final fill = ref.read(blenderBilledFillsProvider).single;
+      expect(fill.label, 'Helium · 12 L · 150.0 bar');
+      expect(fill.isManual, isTrue);
+      expect(fill.total, 27);
+    });
+
+    testWidgets('editing only the pressure of a gas fill saved in cubic feet '
+        'keeps its exact volume (#2302 review)', (tester) async {
+      final ref = await _pump(
+        tester,
+        settings: const AppSettings(
+          defaultCurrency: 'CHF',
+          volumeUnit: VolumeUnit.cubicFeet,
+        ),
+      );
+      ref.read(blenderBilledFillsProvider.notifier).state = const [
+        BilledFill(
+          id: 'a',
+          label: 'AL80',
+          lines: [
+            BilledGasLine(
+              gas: 'O₂',
+              addedBar: 100,
+              cost: 0,
+              cylinderLiters: 11.1,
+              role: BlenderGasRole.o2,
+              startBar: 0,
+            ),
+          ],
+          total: 0,
+        ),
+      ];
+      await tester.pumpAndSettle();
+
+      await tester.tap(find.byTooltip('Actions for AL80'));
+      await tester.pumpAndSettle();
+      await tester.tap(find.text('Edit AL80'));
+      await tester.pumpAndSettle();
+      await tester.enterText(
+        find.byKey(const Key('blender-line-end-pressure')),
+        '150',
+      );
+      await tester.pumpAndSettle();
+      await tester.tap(find.widgetWithText(FilledButton, 'Save'));
+      await tester.pumpAndSettle();
+
+      final line = ref.read(blenderBilledFillsProvider).single.manualGasLine!;
+      expect(line.addedBar, 150);
+      expect(line.cylinderLiters, 11.1);
+      expect(line.freeGasLiters, closeTo(1665, 1e-9));
+    });
+
+    testWidgets('saving an untouched gas fill after a unit change keeps its '
+        'generated label as saved (#2302 review)', (tester) async {
+      final ref = await _pump(
+        tester,
+        settings: const AppSettings(
+          defaultCurrency: 'CHF',
+          pressureUnit: PressureUnit.psi,
+        ),
+      );
+      ref.read(blenderBilledFillsProvider.notifier).state = const [
+        BilledFill(
+          id: 'a',
+          label: 'Helium · 12 L · 150.0 bar',
+          lines: [
+            BilledGasLine(
+              gas: 'Helium',
+              addedBar: 150,
+              cost: 27,
+              cylinderLiters: 12,
+              role: BlenderGasRole.he,
+              startBar: 0,
+            ),
+          ],
+          total: 27,
+        ),
+      ];
+      await tester.pumpAndSettle();
+
+      await tester.tap(find.byTooltip('Actions for Helium · 12 L · 150.0 bar'));
+      await tester.pumpAndSettle();
+      await tester.tap(find.text('Edit Helium · 12 L · 150.0 bar'));
+      await tester.pumpAndSettle();
+      await tester.tap(find.widgetWithText(FilledButton, 'Save'));
+      await tester.pumpAndSettle();
+
+      final fill = ref.read(blenderBilledFillsProvider).single;
+      expect(fill.label, 'Helium · 12 L · 150.0 bar');
+      expect(fill.total, 27);
+    });
+
+    testWidgets('a dot typed under a German locale is read as the decimal '
+        'separator in every field of the line form (#2302 review)', (
+      tester,
+    ) async {
+      // Under de, '.' is the grouping separator, but "12.5" cannot be a
+      // well-formed grouping, so it unambiguously means 12,5 -- the same
+      // correction the blender's other fields apply.
+      final previousLocale = Intl.defaultLocale;
+      Intl.defaultLocale = 'de';
+      addTearDown(() => Intl.defaultLocale = previousLocale);
+      final ref = await _pump(tester);
+      ref.read(blenderGasPricesProvider.notifier).state = const [1.0, 1.5, 0.1];
+
+      await _openAddLine(tester);
+      await tester.enterText(
+        find.byKey(const Key('blender-line-cylinder')),
+        '12.5',
+      );
+      await tester.enterText(
+        find.byKey(const Key('blender-line-start-pressure')),
+        '0.5',
+      );
+      await tester.enterText(
+        find.byKey(const Key('blender-line-end-pressure')),
+        '200.5',
+      );
+      await tester.pumpAndSettle();
+      await tester.tap(find.widgetWithText(FilledButton, 'Save'));
+      await tester.pumpAndSettle();
+
+      final line = ref.read(blenderBilledFillsProvider).single.manualGasLine!;
+      expect(line.cylinderLiters, 12.5);
+      expect(line.startBar, 0.5);
+      expect(line.addedBar, 200);
+
+      await _openAddLine(tester, freeAmount: true);
+      await tester.enterText(
+        find.byKey(const Key('blender-line-description')),
+        'Analyser cell',
+      );
+      await tester.enterText(
+        find.byKey(const Key('blender-line-amount')),
+        '12.5',
+      );
+      await tester.pumpAndSettle();
+      await tester.tap(find.widgetWithText(FilledButton, 'Save'));
+      await tester.pumpAndSettle();
+
+      expect(ref.read(blenderBilledFillsProvider).last.total, 12.5);
+    });
+
+    testWidgets('a fractional fill pressure is shown and labelled to the '
+        'blender\'s tenth of a bar (#2302 review)', (tester) async {
+      final ref = await _pump(tester);
+      await _openAddLine(tester);
+      await tester.enterText(
+        find.byKey(const Key('blender-line-cylinder')),
+        '12',
+      );
+      await tester.enterText(
+        find.byKey(const Key('blender-line-start-pressure')),
+        '50.25',
+      );
+      await tester.enterText(
+        find.byKey(const Key('blender-line-end-pressure')),
+        '200.75',
+      );
+      await tester.pumpAndSettle();
+
+      // Rounded to whole bar this would read 151, a fill that was not made.
+      expect(
+        tester
+            .widget<Text>(find.byKey(const Key('blender-line-fill-pressure')))
+            .data,
+        contains('150.5 bar'),
+      );
+      await tester.tap(find.widgetWithText(FilledButton, 'Save'));
+      await tester.pumpAndSettle();
+
+      final fill = ref.read(blenderBilledFillsProvider).single;
+      expect(fill.manualGasLine!.addedBar, closeTo(150.5, 1e-9));
+      expect(fill.label, endsWith('150.5 bar'));
+    });
+
+    testWidgets('a label generated under a comma-decimal locale still '
+        'regenerates after the app language changes (#2302 review)', (
       tester,
     ) async {
+      final previousLocale = Intl.defaultLocale;
+      addTearDown(() => Intl.defaultLocale = previousLocale);
+      Intl.defaultLocale = 'de';
+      final ref = await _pump(tester);
+
+      await _openAddLine(tester);
+      await _pickGas(tester, 'Helium');
+      await tester.enterText(
+        find.byKey(const Key('blender-line-cylinder')),
+        '12,5',
+      );
+      await tester.enterText(
+        find.byKey(const Key('blender-line-start-pressure')),
+        '0',
+      );
+      await tester.enterText(
+        find.byKey(const Key('blender-line-end-pressure')),
+        '150',
+      );
+      await tester.pumpAndSettle();
+      await tester.tap(find.widgetWithText(FilledButton, 'Save'));
+      await tester.pumpAndSettle();
+      final saved = ref.read(blenderBilledFillsProvider).single.label;
+      expect(saved, 'Helium · 12,5 L · 150,0 bar');
+
+      Intl.defaultLocale = 'en';
+      await tester.tap(find.byTooltip('Actions for $saved'));
+      await tester.pumpAndSettle();
+      await tester.tap(find.text('Edit $saved'));
+      await tester.pumpAndSettle();
+
+      // Recognised as generated, so it is left blank to be regenerated.
+      expect(
+        tester
+            .widget<TextField>(
+              find.byKey(const Key('blender-line-description')),
+            )
+            .controller!
+            .text,
+        isEmpty,
+      );
+      await tester.enterText(
+        find.byKey(const Key('blender-line-end-pressure')),
+        '200',
+      );
+      await tester.pumpAndSettle();
+      await tester.tap(find.widgetWithText(FilledButton, 'Save'));
+      await tester.pumpAndSettle();
+
+      expect(
+        ref.read(blenderBilledFillsProvider).single.label,
+        'Helium · 12.5 L · 200.0 bar',
+      );
+    });
+
+    testWidgets('a computed fill offers neither the kind switch nor the gas '
+        'fields when re-edited', (tester) async {
       final ref = await _pump(tester);
       ref.read(blenderBilledFillsProvider.notifier).state = const [
         BilledFill(
@@ -513,8 +1252,18 @@ void main() {
       await tester.tap(find.text('Edit Tx 18/45'));
       await tester.pumpAndSettle();
 
+      expect(find.byKey(const Key('blender-line-kind')), findsNothing);
       expect(find.byKey(const Key('blender-line-cylinder')), findsNothing);
-      expect(find.widgetWithText(TextField, 'O₂ (%)'), findsNothing);
+      expect(find.byKey(const Key('blender-line-amount')), findsOneWidget);
+
+      // Saving keeps the itemisation it was computed with.
+      await tester.enterText(find.byKey(const Key('blender-line-amount')), '9');
+      await tester.pumpAndSettle();
+      await tester.tap(find.widgetWithText(FilledButton, 'Save'));
+      await tester.pumpAndSettle();
+      final fill = ref.read(blenderBilledFillsProvider).single;
+      expect(fill.lines, hasLength(1));
+      expect(fill.total, 9);
     });
 
     testWidgets('paying asks first, then archives and empties the bill', (
@@ -765,8 +1514,7 @@ void main() {
     /// on screen, then opens the export picker.
     Future<void> addLineAndOpenPicker(WidgetTester tester) async {
       await _pump(tester);
-      await tester.tap(find.byKey(const Key('blender-add-manual-line')));
-      await tester.pumpAndSettle();
+      await _openAddLine(tester, freeAmount: true);
       await tester.enterText(
         find.byKey(const Key('blender-line-description')),
         'Analyser cell',
diff --git a/test/features/gas_calculators/domain/blend_billing_test.dart b/test/features/gas_calculators/domain/blend_billing_test.dart
index 717622b9ea..42acd48f79 100644
--- a/test/features/gas_calculators/domain/blend_billing_test.dart
+++ b/test/features/gas_calculators/domain/blend_billing_test.dart
@@ -178,4 +178,147 @@ void main() {
       expect(result.total, isNotNull);
     });
   });
+
+  group('manualGasFillCost', () {
+    test('prices the pressure between start and end, issue #2302 example', () {
+      final cost = manualGasFillCost(
+        waterLiters: 12,
+        startBar: 50,
+        endBar: 200,
+        pricePer100: 1.5,
+      )!;
+      expect(cost.addedBar, 150);
+      expect(cost.freeGasLiters, 1800);
+      expect(cost.cost, closeTo(27, 1e-9));
+    });
+
+    test('an empty cylinder is filled from 0', () {
+      final cost = manualGasFillCost(
+        waterLiters: 10,
+        startBar: 0,
+        endBar: 232,
+        pricePer100: 2,
+      )!;
+      expect(cost.addedBar, 232);
+      expect(cost.cost, closeTo(46.4, 1e-9));
+    });
+
+    test('a gas without a price is charged at 0, not left unpriced', () {
+      final cost = manualGasFillCost(
+        waterLiters: 12,
+        startBar: 0,
+        endBar: 100,
+        pricePer100: null,
+      )!;
+      expect(cost.freeGasLiters, 1200);
+      expect(cost.cost, 0);
+    });
+
+    test('an end pressure not above the start pressure is rejected', () {
+      expect(
+        manualGasFillCost(
+          waterLiters: 12,
+          startBar: 100,
+          endBar: 100,
+          pricePer100: 1,
+        ),
+        isNull,
+      );
+      expect(
+        manualGasFillCost(
+          waterLiters: 12,
+          startBar: 150,
+          endBar: 100,
+          pricePer100: 1,
+        ),
+        isNull,
+      );
+    });
+
+    test('a negative start pressure or no cylinder is rejected', () {
+      expect(
+        manualGasFillCost(
+          waterLiters: 12,
+          startBar: -1,
+          endBar: 100,
+          pricePer100: 1,
+        ),
+        isNull,
+      );
+      expect(
+        manualGasFillCost(
+          waterLiters: 0,
+          startBar: 0,
+          endBar: 100,
+          pricePer100: 1,
+        ),
+        isNull,
+      );
+    });
+
+    test('a non-finite price is rejected, not treated as unset', () {
+      expect(
+        manualGasFillCost(
+          waterLiters: 12,
+          startBar: 0,
+          endBar: 100,
+          pricePer100: double.nan,
+        ),
+        isNull,
+      );
+      expect(
+        manualGasFillCost(
+          waterLiters: 12,
+          startBar: 0,
+          endBar: 100,
+          pricePer100: double.infinity,
+        ),
+        isNull,
+      );
+    });
+
+    test('finite input that overflows to infinity is rejected', () {
+      // The volume itself overflows.
+      expect(
+        manualGasFillCost(
+          waterLiters: 1e300,
+          startBar: 0,
+          endBar: 1e10,
+          pricePer100: 1,
+        ),
+        isNull,
+      );
+      // The volume is finite, only the cost overflows.
+      expect(
+        manualGasFillCost(
+          waterLiters: 1e300,
+          startBar: 0,
+          endBar: 1,
+          pricePer100: 1e20,
+        ),
+        isNull,
+      );
+    });
+
+    test('non-finite input is rejected rather than priced', () {
+      expect(
+        manualGasFillCost(
+          waterLiters: double.nan,
+          startBar: 0,
+          endBar: 100,
+          pricePer100: 1,
+        ),
+        isNull,
+      );
+      expect(
+        manualGasFillCost(
+          waterLiters: 12,
+          startBar: 0,
+          endBar: double.infinity,
+          pricePer100: 1,
+        ),
+        isNull,
+      );
+    });
+  });
 }