From c4d1acc75b98cb53c21518e856d5228c58664e47 Mon Sep 17 00:00:00 2001
From: Mika Kuns <mika.kuns@fb-tuning.de>
Date: Fri, 19 Jun 2026 10:15:12 +0200
Subject: [PATCH] feat(merge): Rider-style 3-pane conflict editor view

Replace the Base|Ours|Theirs read-only columns + single-conflict result with a
whole-file 3-pane editor: Ours (read-only) | editable Result | Theirs (read-only),
reconstructed from the active file's segments so the panes line up on stable text.

- IBackgroundRenderer paints each conflict block (unresolved=blood, resolved=green)
  across all three panes.
- Result document edits are gated by an IReadOnlySectionProvider (stable text is
  read-only; only conflict regions, tracked via TextAnchors, are editable); edits
  flow back to the owning block.
- Between-pane gutters host inline accept controls (>/< ) positioned per conflict;
  click accepts ours/theirs into the result.
- Proportional synced vertical scroll across the panes; file switcher + change-nav
  arrows (F8 / Shift+F8); active-file 'M conflicts - K resolved' readout.
- Merge block tints + AmberBrush tokens; en/de keys for the new labels.

Seam unchanged. App builds; Ui.Tests 128, Localization.Tests 16.
---
 src/ClaudeDo.Localization/locales/de.json     |  15 +-
 src/ClaudeDo.Localization/locales/en.json     |  15 +-
 src/ClaudeDo.Ui/Design/Tokens.axaml           |   8 +
 .../Conflicts/ConflictResolverViewModel.cs    |   6 +
 .../Conflicts/ConflictResolverView.axaml      | 112 +++---
 .../Conflicts/ConflictResolverView.axaml.cs   | 373 ++++++++++++++++--
 6 files changed, 432 insertions(+), 97 deletions(-)

diff --git a/src/ClaudeDo.Localization/locales/de.json b/src/ClaudeDo.Localization/locales/de.json
index 1ddde29..36d1339 100644
--- a/src/ClaudeDo.Localization/locales/de.json
+++ b/src/ClaudeDo.Localization/locales/de.json
@@ -400,13 +400,14 @@
     "windowTitle": "Merge-Konflikte lösen",
     "modalTitle": "KONFLIKTE LÖSEN",
     "loading": "Konflikte werden geladen…",
-    "current": "Aktuell (unsere)",
-    "incoming": "Eingehend (ihre)",
-    "mergedResult": "Zusammengeführtes Ergebnis",
-    "acceptCurrent": "Aktuelle übernehmen",
-    "acceptIncoming": "Eingehende übernehmen",
-    "acceptBoth": "Beide übernehmen",
-    "editManually": "Manuell bearbeiten",
+    "ours": "OURS · aktuell (Ziel-Branch)",
+    "result": "ERGEBNIS",
+    "theirs": "THEIRS · eingehend (Task)",
+    "binaryHint": "Binärdateien können hier nicht zusammengeführt werden — brich ab und löse sie in deinem Editor:",
+    "prevConflict": "Vorheriger Konflikt (Umschalt+F8)",
+    "nextConflict": "Nächster Konflikt (F8)",
+    "acceptOurs": "Ours ins Ergebnis übernehmen",
+    "acceptTheirs": "Theirs ins Ergebnis übernehmen",
     "continue": "Lösen & fortfahren",
     "abort": "Merge abbrechen"
   },
diff --git a/src/ClaudeDo.Localization/locales/en.json b/src/ClaudeDo.Localization/locales/en.json
index e3b9d1e..0317a6b 100644
--- a/src/ClaudeDo.Localization/locales/en.json
+++ b/src/ClaudeDo.Localization/locales/en.json
@@ -400,13 +400,14 @@
     "windowTitle": "Resolve merge conflicts",
     "modalTitle": "RESOLVE CONFLICTS",
     "loading": "Loading conflicts…",
-    "current": "Current (ours)",
-    "incoming": "Incoming (theirs)",
-    "mergedResult": "Merged result",
-    "acceptCurrent": "Accept Current",
-    "acceptIncoming": "Accept Incoming",
-    "acceptBoth": "Accept Both",
-    "editManually": "Edit manually",
+    "ours": "OURS · current (merge target)",
+    "result": "RESULT",
+    "theirs": "THEIRS · incoming (task)",
+    "binaryHint": "Binary files can't be merged here — abort and resolve them in your editor:",
+    "prevConflict": "Previous conflict (Shift+F8)",
+    "nextConflict": "Next conflict (F8)",
+    "acceptOurs": "Accept ours into result",
+    "acceptTheirs": "Accept theirs into result",
     "continue": "Resolve & continue",
     "abort": "Abort merge"
   },
diff --git a/src/ClaudeDo.Ui/Design/Tokens.axaml b/src/ClaudeDo.Ui/Design/Tokens.axaml
index 8bafa08..d291080 100644
--- a/src/ClaudeDo.Ui/Design/Tokens.axaml
+++ b/src/ClaudeDo.Ui/Design/Tokens.axaml
@@ -100,6 +100,14 @@
   <SolidColorBrush x:Key="DoneTintBrush"          Color="#1F6FA86B" />
   <SolidColorBrush x:Key="DoneTintBorderBrush"    Color="#4C6FA86B" />
 
+  <!-- Merge editor (3-pane conflict resolver) block tints -->
+  <SolidColorBrush x:Key="MergeOursTintBrush"     Color="#1F7C9166" /> <!-- ours side (moss) -->
+  <SolidColorBrush x:Key="MergeTheirsTintBrush"   Color="#1FD4A574" /> <!-- theirs side (amber) -->
+  <SolidColorBrush x:Key="MergeConflictTintBrush" Color="#28C87060" /> <!-- unresolved conflict (blood) -->
+  <SolidColorBrush x:Key="MergeConflictEdgeBrush" Color="#80C87060" /> <!-- unresolved conflict gutter edge -->
+  <SolidColorBrush x:Key="MergeResolvedTintBrush" Color="#206FA86B" /> <!-- resolved conflict (green) -->
+  <SolidColorBrush x:Key="AmberBrush"             Color="#FFD4A574" /> <!-- solid amber (theirs label) -->
+
   <!-- Window-body gradient layers (apply as LinearGradientBrush in the main content Border) -->
   <LinearGradientBrush x:Key="DesktopBackgroundBrush" StartPoint="0%,0%" EndPoint="0%,100%">
     <GradientStop Offset="0"   Color="#FF05070A" />
diff --git a/src/ClaudeDo.Ui/ViewModels/Conflicts/ConflictResolverViewModel.cs b/src/ClaudeDo.Ui/ViewModels/Conflicts/ConflictResolverViewModel.cs
index 06548e8..732fcd4 100644
--- a/src/ClaudeDo.Ui/ViewModels/Conflicts/ConflictResolverViewModel.cs
+++ b/src/ClaudeDo.Ui/ViewModels/Conflicts/ConflictResolverViewModel.cs
@@ -57,6 +57,12 @@ public sealed partial class ConflictResolverViewModel : ObservableObject
         OnPropertyChanged(nameof(ActiveTheirsText));
         OnPropertyChanged(nameof(ActiveResultText));
         OnPropertyChanged(nameof(PositionText));
+        // Keep the focused conflict inside the active file (e.g. when switched via the file picker).
+        if (value is not null && (Current is null || !value.Conflicts.Contains(Current)))
+        {
+            var idx = _flat.FindIndex(x => x.File == value);
+            if (idx >= 0) MoveTo(idx);
+        }
     }
 
     public string ActiveOursText   => ActiveFile?.OursText   ?? "";
diff --git a/src/ClaudeDo.Ui/Views/Conflicts/ConflictResolverView.axaml b/src/ClaudeDo.Ui/Views/Conflicts/ConflictResolverView.axaml
index 0b9d8d6..7a023eb 100644
--- a/src/ClaudeDo.Ui/Views/Conflicts/ConflictResolverView.axaml
+++ b/src/ClaudeDo.Ui/Views/Conflicts/ConflictResolverView.axaml
@@ -7,7 +7,7 @@
         x:DataType="vm:ConflictResolverViewModel"
         x:Class="ClaudeDo.Ui.Views.Conflicts.ConflictResolverView"
         Title="{loc:Tr conflictResolver.windowTitle}"
-        Width="1120" Height="760" MinWidth="840" MinHeight="540"
+        Width="1280" Height="820" MinWidth="960" MinHeight="560"
         CanResize="True"
         WindowDecorations="BorderOnly"
         ExtendClientAreaToDecorationsHint="True"
@@ -17,6 +17,8 @@
 
   <Window.KeyBindings>
     <KeyBinding Gesture="Escape" Command="{Binding AbortCommand}"/>
+    <KeyBinding Gesture="F8" Command="{Binding NextCommand}"/>
+    <KeyBinding Gesture="Shift+F8" Command="{Binding PreviousCommand}"/>
   </Window.KeyBindings>
 
   <Window.Styles>
@@ -24,13 +26,38 @@
       <Setter Property="FontFamily" Value="{StaticResource MonoFont}" />
       <Setter Property="FontSize"   Value="{StaticResource FontSizeMono}" />
       <Setter Property="Background" Value="{DynamicResource Surface2Brush}" />
-      <Setter Property="Padding"    Value="6,4" />
-      <Setter Property="WordWrap"   Value="True" />
+      <Setter Property="Padding"    Value="4,2" />
+      <Setter Property="WordWrap"   Value="False" />
     </Style>
     <Style Selector="Border.col-head">
       <Setter Property="Padding" Value="8,4" />
       <Setter Property="BorderThickness" Value="0,0,0,1" />
       <Setter Property="BorderBrush" Value="{DynamicResource LineBrush}" />
+      <Setter Property="Background" Value="{DynamicResource Surface2Brush}" />
+    </Style>
+    <Style Selector="Border.pane">
+      <Setter Property="BorderBrush" Value="{DynamicResource LineBrush}" />
+      <Setter Property="BorderThickness" Value="1" />
+      <Setter Property="CornerRadius" Value="6" />
+      <Setter Property="ClipToBounds" Value="True" />
+    </Style>
+    <!-- Inline accept controls in the between-pane gutters -->
+    <Style Selector="Button.accept-gutter">
+      <Setter Property="Width" Value="22" />
+      <Setter Property="Height" Value="20" />
+      <Setter Property="Padding" Value="0" />
+      <Setter Property="FontSize" Value="13" />
+      <Setter Property="FontWeight" Value="Bold" />
+      <Setter Property="HorizontalContentAlignment" Value="Center" />
+      <Setter Property="VerticalContentAlignment" Value="Center" />
+      <Setter Property="Background" Value="{DynamicResource Surface2Brush}" />
+      <Setter Property="BorderBrush" Value="{DynamicResource MergeConflictEdgeBrush}" />
+      <Setter Property="BorderThickness" Value="1" />
+      <Setter Property="CornerRadius" Value="4" />
+      <Setter Property="Foreground" Value="{DynamicResource TextBrush}" />
+    </Style>
+    <Style Selector="Button.accept-gutter:pointerover /template/ ContentPresenter">
+      <Setter Property="Background" Value="{DynamicResource MergeConflictTintBrush}" />
     </Style>
   </Window.Styles>
 
@@ -49,7 +76,7 @@
       </Grid>
     </ctl:ModalShell.Footer>
 
-    <Grid Margin="14,10" RowDefinitions="Auto,Auto,Auto,*,Auto,Auto,*">
+    <Grid Margin="14,10" RowDefinitions="Auto,Auto,Auto,*">
 
       <!-- Busy / error -->
       <TextBlock Grid.Row="0" Classes="meta" Margin="0,0,0,6"
@@ -65,7 +92,7 @@
               IsVisible="{Binding HasBinaryFiles}">
         <StackPanel Spacing="3">
           <TextBlock Classes="meta" Foreground="{DynamicResource BloodBrush}"
-                     Text="Binary files can't be merged here — abort and resolve them in your editor:"/>
+                     Text="{loc:Tr conflictResolver.binaryHint}"/>
           <ItemsControl ItemsSource="{Binding BinaryFilePaths}">
             <ItemsControl.ItemTemplate>
               <DataTemplate x:DataType="x:String">
@@ -76,69 +103,64 @@
         </StackPanel>
       </Border>
 
-      <!-- Navigation header -->
-      <Grid Grid.Row="2" ColumnDefinitions="Auto,Auto,*,Auto" Margin="0,0,0,8"
+      <!-- Toolbar: change nav · file switcher · readout -->
+      <Grid Grid.Row="2" ColumnDefinitions="Auto,Auto,Auto,*,Auto" Margin="0,0,0,8"
             IsVisible="{Binding HasCurrent}">
-        <Button Grid.Column="0" Classes="btn" Content="◀ Prev" Margin="0,0,6,0"
+        <Button Grid.Column="0" Classes="btn" Content="↑" Margin="0,0,4,0" Padding="10,4"
+                ToolTip.Tip="{loc:Tr conflictResolver.prevConflict}"
                 Command="{Binding PreviousCommand}"/>
-        <Button Grid.Column="1" Classes="btn" Content="Next ▶"
+        <Button Grid.Column="1" Classes="btn" Content="↓" Margin="0,0,12,0" Padding="10,4"
+                ToolTip.Tip="{loc:Tr conflictResolver.nextConflict}"
                 Command="{Binding NextCommand}"/>
-        <TextBlock Grid.Column="2" Classes="path-mono" VerticalAlignment="Center"
-                   Margin="14,0" TextTrimming="CharacterEllipsis"
-                   Text="{Binding CurrentPath}"/>
-        <TextBlock Grid.Column="3" Classes="meta" VerticalAlignment="Center"
+        <ComboBox Grid.Column="2" MinWidth="240" MaxWidth="520"
+                  ItemsSource="{Binding Files}"
+                  SelectedItem="{Binding ActiveFile, Mode=TwoWay}">
+          <ComboBox.ItemTemplate>
+            <DataTemplate x:DataType="vm:MergeFile">
+              <TextBlock Classes="path-mono" Text="{Binding Path}" TextTrimming="CharacterEllipsis"/>
+            </DataTemplate>
+          </ComboBox.ItemTemplate>
+        </ComboBox>
+        <TextBlock Grid.Column="4" Classes="meta" VerticalAlignment="Center"
                    Foreground="{DynamicResource TextDimBrush}"
                    Text="{Binding PositionText}"/>
       </Grid>
 
-      <!-- Three-way columns: Base | Ours | Theirs -->
-      <Grid Grid.Row="3" ColumnDefinitions="*,*,*" IsVisible="{Binding HasCurrent}">
-        <Border Grid.Column="0" BorderBrush="{DynamicResource LineBrush}" BorderThickness="1" CornerRadius="6" Margin="0,0,4,0">
+      <!-- Three panes: Ours | (gutter) | Result | (gutter) | Theirs -->
+      <Grid Grid.Row="3" ColumnDefinitions="*,26,*,26,*" IsVisible="{Binding HasCurrent}">
+        <Border Grid.Column="0" Classes="pane">
           <DockPanel>
             <Border Classes="col-head" DockPanel.Dock="Top">
-              <TextBlock Classes="eyebrow" Text="BASE"/>
+              <TextBlock Classes="eyebrow" Text="{loc:Tr conflictResolver.ours}"
+                         Foreground="{DynamicResource MossBrush}"/>
             </Border>
-            <ae:TextEditor Name="BaseEditor" IsReadOnly="True"/>
+            <ae:TextEditor Name="OursEditor" IsReadOnly="True" ShowLineNumbers="True"/>
           </DockPanel>
         </Border>
-        <Border Grid.Column="1" BorderBrush="{DynamicResource LineBrush}" BorderThickness="1" CornerRadius="6" Margin="4,0">
+
+        <Canvas Grid.Column="1" Name="LeftGutter" Background="Transparent"/>
+
+        <Border Grid.Column="2" Classes="pane">
           <DockPanel>
             <Border Classes="col-head" DockPanel.Dock="Top">
-              <TextBlock Classes="eyebrow" Text="OURS · current (merge target)" Foreground="{DynamicResource MossBrush}"/>
+              <TextBlock Classes="eyebrow" Text="{loc:Tr conflictResolver.result}"/>
             </Border>
-            <ae:TextEditor Name="OursEditor" IsReadOnly="True"/>
+            <ae:TextEditor Name="ResultEditor" ShowLineNumbers="True"/>
           </DockPanel>
         </Border>
-        <Border Grid.Column="2" BorderBrush="{DynamicResource LineBrush}" BorderThickness="1" CornerRadius="6" Margin="4,0,0,0">
+
+        <Canvas Grid.Column="3" Name="RightGutter" Background="Transparent"/>
+
+        <Border Grid.Column="4" Classes="pane">
           <DockPanel>
             <Border Classes="col-head" DockPanel.Dock="Top">
-              <TextBlock Classes="eyebrow" Text="THEIRS · incoming (task)" Foreground="{DynamicResource AccentBrush}"/>
+              <TextBlock Classes="eyebrow" Text="{loc:Tr conflictResolver.theirs}"
+                         Foreground="{DynamicResource AmberBrush}"/>
             </Border>
-            <ae:TextEditor Name="TheirsEditor" IsReadOnly="True"/>
+            <ae:TextEditor Name="TheirsEditor" IsReadOnly="True" ShowLineNumbers="True"/>
           </DockPanel>
         </Border>
       </Grid>
-
-      <!-- Accept actions -->
-      <WrapPanel Grid.Row="4" Orientation="Horizontal" Margin="0,8" IsVisible="{Binding HasCurrent}">
-        <Button Classes="btn" Content="Accept Ours" Margin="0,0,8,0"
-                Command="{Binding Current.AcceptOursCommand}"/>
-        <Button Classes="btn" Content="Accept Base" Margin="0,0,8,0"
-                IsEnabled="{Binding Current.HasBase}"
-                Command="{Binding Current.AcceptBaseCommand}"/>
-        <Button Classes="btn" Content="Accept Theirs" Margin="0,0,8,0"
-                Command="{Binding Current.AcceptTheirsCommand}"/>
-        <Button Classes="btn" Content="Accept Both" Margin="0,0,8,0"
-                Command="{Binding Current.AcceptBothCommand}"/>
-      </WrapPanel>
-
-      <!-- Merged result -->
-      <TextBlock Grid.Row="5" Classes="eyebrow" Text="MERGED RESULT" Margin="0,4,0,4"
-                 IsVisible="{Binding HasCurrent}"/>
-      <Border Grid.Row="6" BorderBrush="{DynamicResource LineBrush}" BorderThickness="1" CornerRadius="6"
-              IsVisible="{Binding HasCurrent}">
-        <ae:TextEditor Name="ResultEditor" ShowLineNumbers="True"/>
-      </Border>
     </Grid>
   </ctl:ModalShell>
 </Window>
diff --git a/src/ClaudeDo.Ui/Views/Conflicts/ConflictResolverView.axaml.cs b/src/ClaudeDo.Ui/Views/Conflicts/ConflictResolverView.axaml.cs
index 3a21505..b1c366f 100644
--- a/src/ClaudeDo.Ui/Views/Conflicts/ConflictResolverView.axaml.cs
+++ b/src/ClaudeDo.Ui/Views/Conflicts/ConflictResolverView.axaml.cs
@@ -1,8 +1,18 @@
 using System;
+using System.Collections.Generic;
 using System.ComponentModel;
 using System.IO;
+using System.Linq;
+using System.Text;
+using Avalonia;
 using Avalonia.Controls;
+using Avalonia.Media;
+using Avalonia.Threading;
+using Avalonia.VisualTree;
 using AvaloniaEdit;
+using AvaloniaEdit.Document;
+using AvaloniaEdit.Editing;
+using AvaloniaEdit.Rendering;
 using AvaloniaEdit.TextMate;
 using ClaudeDo.Ui.ViewModels.Conflicts;
 using TextMateSharp.Grammars;
@@ -13,9 +23,21 @@ public partial class ConflictResolverView : Window
 {
     private ConflictResolverViewModel? _vm;
     private RegistryOptions? _registry;
-    private TextMate.Installation? _baseTm, _oursTm, _theirsTm, _resultTm;
-    private MergeConflictBlock? _hooked;
-    private bool _reloading;
+    private TextMate.Installation? _oursTm, _resultTm, _theirsTm;
+
+    // Fixed conflict spans for the read-only side panes (recomputed each rebuild).
+    private List<(int Offset, int Length, MergeConflictBlock Block)> _oursSpans = new();
+    private List<(int Offset, int Length, MergeConflictBlock Block)> _theirsSpans = new();
+
+    // Live, edit-tracked conflict regions in the editable result document.
+    private readonly List<(MergeConflictBlock Block, TextAnchor Start, TextAnchor End)> _resultRegions = new();
+    private readonly List<MergeConflictBlock> _hookedBlocks = new();
+
+    private ScrollViewer?[] _scrollViewers = Array.Empty<ScrollViewer?>();
+    private bool _wired;
+    private bool _rebuilding;
+    private bool _applyingAccept;
+    private bool _syncing;
 
     public ConflictResolverView()
     {
@@ -26,62 +48,280 @@ public partial class ConflictResolverView : Window
     {
         base.OnDataContextChanged(e);
 
-        if (_vm is not null) _vm.CurrentChanged -= ReloadEditors;
+        if (_vm is not null)
+        {
+            _vm.ActiveFileChanged -= Rebuild;
+            _vm.CurrentChanged -= ScrollToCurrent;
+        }
         _vm = DataContext as ConflictResolverViewModel;
         if (_vm is null) return;
 
         _vm.CloseRequested = Close;
-        EnsureTextMate();
-        _vm.CurrentChanged += ReloadEditors;
-        ResultEditor.TextChanged += OnResultEditorChanged;
-        ReloadEditors();
+        EnsureEditors();
+        _vm.ActiveFileChanged += Rebuild;
+        _vm.CurrentChanged += ScrollToCurrent;
+        Rebuild();
     }
 
-    private void EnsureTextMate()
+    // ── One-time editor setup ────────────────────────────────────────────────
+
+    private void EnsureEditors()
     {
         if (_registry is not null) return;
         _registry = new RegistryOptions(ThemeName.DarkPlus);
-        _baseTm   = BaseEditor.InstallTextMate(_registry);
         _oursTm   = OursEditor.InstallTextMate(_registry);
-        _theirsTm = TheirsEditor.InstallTextMate(_registry);
         _resultTm = ResultEditor.InstallTextMate(_registry);
+        _theirsTm = TheirsEditor.InstallTextMate(_registry);
+
+        ResultEditor.Document ??= new TextDocument();
+        ResultEditor.Document.Changed += OnResultDocumentChanged;
+        ResultEditor.TextArea.ReadOnlySectionProvider =
+            new ConflictReadOnlyProvider(() => _resultRegions.Select(r => (r.Start.Offset, r.End.Offset)));
+
+        var conflict = BrushRes("MergeConflictTintBrush", Color.Parse("#28C87060"));
+        var resolved = BrushRes("MergeResolvedTintBrush", Color.Parse("#206FA86B"));
+        OursEditor.TextArea.TextView.BackgroundRenderers.Add(new MergeBlockRenderer(
+            () => _oursSpans.Select(s => (s.Offset, s.Length, s.Block.IsResolved)), conflict, resolved));
+        ResultEditor.TextArea.TextView.BackgroundRenderers.Add(new MergeBlockRenderer(
+            () => _resultRegions.Select(r => (r.Start.Offset, r.End.Offset - r.Start.Offset, r.Block.IsResolved)), conflict, resolved));
+        TheirsEditor.TextArea.TextView.BackgroundRenderers.Add(new MergeBlockRenderer(
+            () => _theirsSpans.Select(s => (s.Offset, s.Length, s.Block.IsResolved)), conflict, resolved));
     }
 
-    private void ReloadEditors()
+    private IBrush BrushRes(string key, Color fallback)
+    {
+        if (this.TryGetResource(key, null, out var v) && v is IBrush b)
+            return b;
+        return new SolidColorBrush(fallback);
+    }
+
+    // ── Rebuild the three documents for the active file ───────────────────────
+
+    private void Rebuild()
     {
         if (_vm is null) return;
-        _reloading = true;
+        _rebuilding = true;
         try
         {
-            if (_hooked is not null) _hooked.PropertyChanged -= OnCurrentResolutionChanged;
-            _hooked = _vm.Current;
-            if (_hooked is not null) _hooked.PropertyChanged += OnCurrentResolutionChanged;
+            ClearGutters();
+            UnhookBlocks();
+            _resultRegions.Clear();
 
-            BaseEditor.Text   = _vm.Current?.Base ?? "";
-            OursEditor.Text   = _vm.Current?.Ours ?? "";
-            TheirsEditor.Text = _vm.Current?.Theirs ?? "";
-            ResultEditor.Text = _vm.Current?.Resolution ?? "";
-            ApplyGrammar(_vm.CurrentPath);
+            var file = _vm.ActiveFile;
+            if (file is null || file.IsBinary)
+            {
+                OursEditor.Text = TheirsEditor.Text = "";
+                if (ResultEditor.Document is { } d0) d0.Text = "";
+                _oursSpans = new(); _theirsSpans = new();
+                InvalidateRenderers();
+                return;
+            }
+
+            var (oursText, oursSpans) = BuildSide(file, b => b.Ours);
+            var (theirsText, theirsSpans) = BuildSide(file, b => b.Theirs);
+            var (resultText, resultSpans) = BuildSide(file, b => b.Resolution ?? b.Ours);
+            _oursSpans = oursSpans;
+            _theirsSpans = theirsSpans;
+
+            OursEditor.Text = oursText;
+            TheirsEditor.Text = theirsText;
+            ResultEditor.Document ??= new TextDocument();
+            ResultEditor.Document.Text = resultText;
+
+            var doc = ResultEditor.Document;
+            foreach (var (offset, length, block) in resultSpans)
+            {
+                var start = doc.CreateAnchor(offset);
+                start.MovementType = AnchorMovementType.BeforeInsertion;
+                var end = doc.CreateAnchor(offset + length);
+                end.MovementType = AnchorMovementType.AfterInsertion;
+                _resultRegions.Add((block, start, end));
+                block.PropertyChanged += OnBlockChanged;
+                _hookedBlocks.Add(block);
+            }
+
+            ApplyGrammar(file.Path);
+            InvalidateRenderers();
         }
-        finally { _reloading = false; }
+        finally { _rebuilding = false; }
+
+        if (!_wired)
+        {
+            _wired = true;
+            Dispatcher.UIThread.Post(HookScrollSync, DispatcherPriority.Loaded);
+        }
+        Dispatcher.UIThread.Post(PositionGutters, DispatcherPriority.Loaded);
     }
 
-    // User edits in the result editor flow back to the current conflict's resolution.
-    private void OnResultEditorChanged(object? sender, EventArgs e)
+    private static (string Text, List<(int Offset, int Length, MergeConflictBlock Block)> Spans) BuildSide(
+        MergeFile file, Func<MergeConflictBlock, string> pick)
     {
-        if (_reloading || _vm?.Current is null) return;
-        _vm.Current.Resolution = ResultEditor.Text;
+        var sb = new StringBuilder();
+        var spans = new List<(int, int, MergeConflictBlock)>();
+        foreach (var seg in file.Segments)
+        {
+            if (seg.IsConflict)
+            {
+                var text = pick(seg.Conflict!);
+                spans.Add((sb.Length, text.Length, seg.Conflict!));
+                sb.Append(text);
+            }
+            else
+            {
+                sb.Append(seg.StableText);
+            }
+        }
+        return (sb.ToString(), spans);
     }
 
-    // Accept-buttons set Resolution on the VM; mirror that into the result editor.
-    private void OnCurrentResolutionChanged(object? sender, PropertyChangedEventArgs e)
+    private void UnhookBlocks()
     {
-        if (_reloading || e.PropertyName != nameof(MergeConflictBlock.Resolution)) return;
-        var resolved = _vm?.Current?.Resolution ?? "";
-        if (ResultEditor.Text == resolved) return;
-        _reloading = true;
-        try { ResultEditor.Text = resolved; }
-        finally { _reloading = false; }
+        foreach (var b in _hookedBlocks) b.PropertyChanged -= OnBlockChanged;
+        _hookedBlocks.Clear();
+    }
+
+    private void OnBlockChanged(object? sender, PropertyChangedEventArgs e)
+    {
+        if (e.PropertyName is nameof(MergeConflictBlock.IsResolved) or nameof(MergeConflictBlock.Resolution))
+        {
+            InvalidateRenderers();
+            Dispatcher.UIThread.Post(PositionGutters, DispatcherPriority.Background);
+        }
+    }
+
+    // ── User edits in the result document flow back to the owning conflict ────
+
+    private void OnResultDocumentChanged(object? sender, DocumentChangeEventArgs e)
+    {
+        if (_rebuilding || _applyingAccept) return;
+        foreach (var (block, start, end) in _resultRegions)
+        {
+            if (e.Offset >= start.Offset && e.Offset <= end.Offset)
+            {
+                block.Resolution = ResultEditor.Document.GetText(start.Offset, Math.Max(0, end.Offset - start.Offset));
+                break;
+            }
+        }
+        Dispatcher.UIThread.Post(PositionGutters, DispatcherPriority.Background);
+    }
+
+    // ── Accept a side into the result ────────────────────────────────────────
+
+    private void AcceptOurs(MergeConflictBlock block) => AcceptInto(block, block.Ours);
+    private void AcceptTheirs(MergeConflictBlock block) => AcceptInto(block, block.Theirs);
+
+    private void AcceptInto(MergeConflictBlock block, string text)
+    {
+        var region = _resultRegions.FirstOrDefault(r => ReferenceEquals(r.Block, block));
+        if (region.Block is null) return;
+        _applyingAccept = true;
+        try
+        {
+            ResultEditor.Document.Replace(region.Start.Offset, region.End.Offset - region.Start.Offset, text);
+        }
+        finally { _applyingAccept = false; }
+        block.Resolution = text;
+        InvalidateRenderers();
+        PositionGutters();
+    }
+
+    // ── Inline accept controls in the between-pane gutters ────────────────────
+
+    private void ClearGutters()
+    {
+        LeftGutter.Children.Clear();
+        RightGutter.Children.Clear();
+    }
+
+    private void PositionGutters()
+    {
+        ClearGutters();
+        if (_vm?.ActiveFile is null) return;
+        var tv = ResultEditor.TextArea.TextView;
+        if (!tv.VisualLinesValid)
+        {
+            Dispatcher.UIThread.Post(PositionGutters, DispatcherPriority.Background);
+            return;
+        }
+
+        var doc = ResultEditor.Document;
+        foreach (var (block, start, end) in _resultRegions)
+        {
+            if (block.IsResolved) continue;
+            var len = end.Offset - start.Offset;
+            ISegment probe = len > 0
+                ? new Seg(start.Offset, len)
+                : new Seg(start.Offset, start.Offset < doc.TextLength ? 1 : 0);
+            var rects = BackgroundGeometryBuilder.GetRectsForSegment(tv, probe).ToList();
+            if (rects.Count == 0) continue;
+            var y = rects[0].Top;
+
+            var capturedBlock = block;
+            if (tv.TranslatePoint(new Point(0, y), LeftGutter) is { } pl &&
+                pl.Y > -24 && pl.Y < LeftGutter.Bounds.Height + 24)
+                AddAcceptButton(LeftGutter, pl.Y, "›", () => AcceptOurs(capturedBlock),
+                    Tr("conflictResolver.acceptOurs"));
+
+            if (tv.TranslatePoint(new Point(0, y), RightGutter) is { } pr &&
+                pr.Y > -24 && pr.Y < RightGutter.Bounds.Height + 24)
+                AddAcceptButton(RightGutter, pr.Y, "‹", () => AcceptTheirs(capturedBlock),
+                    Tr("conflictResolver.acceptTheirs"));
+        }
+    }
+
+    private void AddAcceptButton(Canvas canvas, double y, string glyph, Action onClick, string tip)
+    {
+        var b = new Button { Content = glyph };
+        b.Classes.Add("accept-gutter");
+        ToolTip.SetTip(b, tip);
+        b.Click += (_, _) => onClick();
+        Canvas.SetLeft(b, 1);
+        Canvas.SetTop(b, Math.Max(0, y));
+        canvas.Children.Add(b);
+    }
+
+    private static string Tr(string key) => ClaudeDo.Ui.Localization.Loc.T(key);
+
+    // ── Synced vertical scroll across the three panes ─────────────────────────
+
+    private void HookScrollSync()
+    {
+        _scrollViewers = new[] { OursEditor, ResultEditor, TheirsEditor }
+            .Select(ed => ed.FindDescendantOfType<ScrollViewer>())
+            .ToArray();
+        foreach (var sv in _scrollViewers)
+            if (sv is not null) sv.ScrollChanged += OnPaneScroll;
+    }
+
+    private void OnPaneScroll(object? sender, ScrollChangedEventArgs e)
+    {
+        if (_syncing || sender is not ScrollViewer src) return;
+        _syncing = true;
+        try
+        {
+            foreach (var sv in _scrollViewers)
+                if (sv is not null && !ReferenceEquals(sv, src) && Math.Abs(sv.Offset.Y - src.Offset.Y) > 0.5)
+                    sv.Offset = new Vector(sv.Offset.X, src.Offset.Y);
+        }
+        finally { _syncing = false; }
+        PositionGutters();
+    }
+
+    private void ScrollToCurrent()
+    {
+        if (_vm?.Current is not { } block) return;
+        var region = _resultRegions.FirstOrDefault(r => ReferenceEquals(r.Block, block));
+        if (region.Block is null) return;
+        var line = ResultEditor.Document.GetLineByOffset(region.Start.Offset).LineNumber;
+        ResultEditor.ScrollToLine(line);
+        Dispatcher.UIThread.Post(PositionGutters, DispatcherPriority.Background);
+    }
+
+    private void InvalidateRenderers()
+    {
+        OursEditor.TextArea.TextView.InvalidateVisual();
+        ResultEditor.TextArea.TextView.InvalidateVisual();
+        TheirsEditor.TextArea.TextView.InvalidateVisual();
     }
 
     private void ApplyGrammar(string? path)
@@ -89,14 +329,71 @@ public partial class ConflictResolverView : Window
         if (_registry is null || string.IsNullOrEmpty(path)) return;
         var ext = Path.GetExtension(path);
         if (string.IsNullOrEmpty(ext)) return;
-
         var language = _registry.GetLanguageByExtension(ext);
         if (language is null) return;
-
         var scope = _registry.GetScopeByLanguageId(language.Id);
-        _baseTm?.SetGrammar(scope);
         _oursTm?.SetGrammar(scope);
-        _theirsTm?.SetGrammar(scope);
         _resultTm?.SetGrammar(scope);
+        _theirsTm?.SetGrammar(scope);
+    }
+
+    // ── Helper types (single-consumer; live with their consumer per repo style) ─
+
+    /// <summary>A minimal <see cref="ISegment"/> for geometry/read-only queries.</summary>
+    private readonly struct Seg : ISegment
+    {
+        public Seg(int offset, int length) { Offset = offset; Length = length; }
+        public int Offset { get; }
+        public int Length { get; }
+        public int EndOffset => Offset + Length;
+    }
+
+    /// <summary>Paints each conflict block with the unresolved/resolved tint across a pane.</summary>
+    private sealed class MergeBlockRenderer : IBackgroundRenderer
+    {
+        private readonly Func<IEnumerable<(int Offset, int Length, bool Resolved)>> _spans;
+        private readonly IBrush _conflict;
+        private readonly IBrush _resolved;
+
+        public MergeBlockRenderer(Func<IEnumerable<(int, int, bool)>> spans, IBrush conflict, IBrush resolved)
+        {
+            _spans = spans; _conflict = conflict; _resolved = resolved;
+        }
+
+        public KnownLayer Layer => KnownLayer.Background;
+
+        public void Draw(TextView textView, DrawingContext drawingContext)
+        {
+            if (!textView.VisualLinesValid) return;
+            foreach (var (offset, length, resolved) in _spans())
+            {
+                ISegment seg = new Seg(offset, Math.Max(length, 0));
+                var builder = new BackgroundGeometryBuilder { AlignToWholePixels = true, CornerRadius = 2 };
+                builder.AddSegment(textView, seg);
+                var geo = builder.CreateGeometry();
+                if (geo is not null)
+                    drawingContext.DrawGeometry(resolved ? _resolved : _conflict, null, geo);
+            }
+        }
+    }
+
+    /// <summary>Makes everything read-only except the live conflict regions in the result document.</summary>
+    private sealed class ConflictReadOnlyProvider : IReadOnlySectionProvider
+    {
+        private readonly Func<IEnumerable<(int Start, int End)>> _regions;
+        public ConflictReadOnlyProvider(Func<IEnumerable<(int, int)>> regions) => _regions = regions;
+
+        public bool CanInsert(int offset) => _regions().Any(r => offset >= r.Start && offset <= r.End);
+
+        public IEnumerable<ISegment> GetDeletableSegments(ISegment segment)
+        {
+            foreach (var (start, end) in _regions())
+            {
+                var s = Math.Max(segment.Offset, start);
+                var e = Math.Min(segment.EndOffset, end);
+                if (e > s) yield return new Seg(s, e - s);
+                else if (e == s && segment.Length == 0 && s >= start && s <= end) yield return new Seg(s, 0);
+            }
+        }
     }
 }