feat(merge): diff Merge opens the 3-pane editor + conflict overview ruler

- The Merge button in the Diff window now hands a conflicting merge to the in-app
  3-pane editor (MergeModal routes 'conflict' through RequestConflictResolution,
  the same seam Approve uses) instead of dead-ending on a conflict message.
- Add a conflict overview ruler right of the Result pane: a proportional map of
  every conflict in the file, recolored by resolved state, click a tick to jump —
  so conflicts are findable in long files without scrolling.
- New MergeResolvedEdgeBrush token + conflictMap en/de key. Ui 128 + Loc 16 green.

src/ClaudeDo.Localization/locales/de.json

@@ -406,6 +406,7 @@
     "binaryHint": "Binärdateien können hier nicht zusammengeführt werden — brich ab und löse sie in deinem Editor:",
     "prevConflict": "Vorheriger Konflikt (Umschalt+F8)",
     "nextConflict": "Nächster Konflikt (F8)",
+    "conflictMap": "Konflikte in dieser Datei — Marker anklicken zum Springen",
     "acceptOurs": "Main hinzufügen",
     "acceptTheirs": "Incoming hinzufügen",
     "removeOurs": "Main entfernen",

src/ClaudeDo.Localization/locales/en.json

@@ -406,6 +406,7 @@
     "binaryHint": "Binary files can't be merged here — abort and resolve them in your editor:",
     "prevConflict": "Previous conflict (Shift+F8)",
     "nextConflict": "Next conflict (F8)",
+    "conflictMap": "Conflicts in this file — click a marker to jump",
     "acceptOurs": "Add main",
     "acceptTheirs": "Add incoming",
     "removeOurs": "Remove main",

src/ClaudeDo.Ui/CLAUDE.md

@@ -41,7 +41,7 @@ Design/     — Tokens.axaml (design tokens; merged before styles) + IslandStyle
 - **NotesEditorViewModel** — day navigator + bullet CRUD for daily notes via `INotesApi`.
 - **Modal VMs** — `SettingsModalViewModel` (four tabs: General, Worktrees, Files prompt-paths, Prime Claude incl. `DailyPrepMaxTasks` + prime-schedule rows), `ListSettingsModalViewModel` (name, working dir, commit type, per-list Model/SystemPrompt/AgentPath/MaxTurns with inherited-badge + reset, delete list), `RepoImportModalViewModel` (bulk-create lists from git repos found under chosen parents; already-wired repos disabled), `WeeklyReportModalViewModel` (range pickers default "since last standup weekday → today", cached per range, markdown via MarkdownView), `MergeModalViewModel` (single-task merge form, called from the diff modal), `WorktreesOverviewModalViewModel` (global/per-list worktree rows, batch merge + state ops), `UnfinishedPlanningModalViewModel` (Resume/FinalizeNow/Discard for a draft planning session), `WorkerConnectionModalViewModel` (offline help), `AboutModalViewModel`.
 - **Diff stack** — `UnifiedDiffParser` (static; parses `git diff` output into `DiffFileViewModel`s, detecting added/deleted/renamed/binary files and per-line numbers; `Flatten` injects file-header rows for a combined single-pane view). `DiffModalViewModel` has two modes: live worktree (branch diff vs base, with a Merge action) and commit-range `base..head` (`FromCommitRange = true` — shows a merged task's diff after its worktree is gone; no merge action). The view renders a file list with binary/empty placeholders via `DiffLinesView`.
-- **Planning/Conflicts** — `PlanningDiffViewModel` (per-subtask diffs via `GetPlanningAggregateAsync`, toggle to combined integration-branch diff, conflict warnings), `ConflictResolverViewModel` (in-app **Rider-style 3-pane merge editor** for both single-task and planning unit-merge conflicts: single-task starts the conflict merge, parses each conflicted file into stable/conflict `MergeFileSegment`s via the worker's `GetMergeConflictDocuments`; exposes the active file's three reconstructed documents — `ActiveOursText` / `ActiveResultText` / `ActiveTheirsText` (from `MergeFile.OursText/ResultText/TheirsText`; Result seeds unresolved conflicts with Ours) — plus `ActiveFile`/`SelectFileCommand` (multi-file switcher), `Current`/`Next`/`Previous` (focused-conflict nav), a per-active-file `PositionText` readout, per-block `AcceptOurs/Theirs/Both/Base` + `MergeFile.Compose`, and `CanContinue` gated on every file resolved + no binary; writes each file via `WriteConflictResolution`, continue/abort; **planning mode** via `OpenForPlanningAsync(parentId, subtaskId)` loads the current subtask's mid-merge conflicts without re-starting the merge and routes continue/abort to `ContinuePlanningMerge`/`AbortPlanningMerge`, so a unit-merge conflict re-opens the editor per subtask via the `PlanningMergeConflict` broadcast). The view (`Views/Conflicts/ConflictResolverView`) shows the whole file in three **AvaloniaEdit** panes — MAIN/ours (read-only) | editable Result | INCOMING/theirs (read-only) — with TextMate highlighting by extension (theme `StyleInclude` in `App.axaml`); a code-behind `IBackgroundRenderer` tints each conflict block (unresolved/resolved) across panes, an `IReadOnlySectionProvider` + `TextAnchor` regions keep only conflict spans editable in Result (edits flow back to the block); each unresolved conflict starts EMPTY (a thin marker bar); the between-pane gutter controls **toggle** each side in/out of the result — `›`/`‹` add MAIN/INCOMING in click order (first pick on top), clicking again removes that side — so a conflict can take main, incoming, both, or neither; a `FilesSummary` readout shows how many files still have conflicts, and the three panes share a proportional synced vertical scroll. Conflict block tints live in `Tokens.axaml` (`Merge*TintBrush`).
+- **Planning/Conflicts** — `PlanningDiffViewModel` (per-subtask diffs via `GetPlanningAggregateAsync`, toggle to combined integration-branch diff, conflict warnings), `ConflictResolverViewModel` (in-app **Rider-style 3-pane merge editor** for both single-task and planning unit-merge conflicts: single-task starts the conflict merge, parses each conflicted file into stable/conflict `MergeFileSegment`s via the worker's `GetMergeConflictDocuments`; exposes the active file's three reconstructed documents — `ActiveOursText` / `ActiveResultText` / `ActiveTheirsText` (from `MergeFile.OursText/ResultText/TheirsText`; Result seeds unresolved conflicts with Ours) — plus `ActiveFile`/`SelectFileCommand` (multi-file switcher), `Current`/`Next`/`Previous` (focused-conflict nav), a per-active-file `PositionText` readout, per-block `AcceptOurs/Theirs/Both/Base` + `MergeFile.Compose`, and `CanContinue` gated on every file resolved + no binary; writes each file via `WriteConflictResolution`, continue/abort; **planning mode** via `OpenForPlanningAsync(parentId, subtaskId)` loads the current subtask's mid-merge conflicts without re-starting the merge and routes continue/abort to `ContinuePlanningMerge`/`AbortPlanningMerge`, so a unit-merge conflict re-opens the editor per subtask via the `PlanningMergeConflict` broadcast). The view (`Views/Conflicts/ConflictResolverView`) shows the whole file in three **AvaloniaEdit** panes — MAIN/ours (read-only) | editable Result | INCOMING/theirs (read-only) — with TextMate highlighting by extension (theme `StyleInclude` in `App.axaml`); a code-behind `IBackgroundRenderer` tints each conflict block (unresolved/resolved) across panes, an `IReadOnlySectionProvider` + `TextAnchor` regions keep only conflict spans editable in Result (edits flow back to the block); each unresolved conflict starts EMPTY (a thin marker bar); the between-pane gutter controls **toggle** each side in/out of the result — `›`/`‹` add MAIN/INCOMING in click order (first pick on top), clicking again removes that side — so a conflict can take main, incoming, both, or neither; a `FilesSummary` readout shows how many files still have conflicts, and the three panes share a proportional synced vertical scroll. A conflict overview ruler right of the Result pane (`ConflictMap`) maps every conflict in the file proportionally (click a tick to jump) — handy for long files. Conflict block tints live in `Tokens.axaml` (`Merge*TintBrush`). The editor is reached from review **Approve** on conflict and from the **Merge** button in the Diff window (a conflicting `MergeTask` hands off to the resolver via `RequestConflictResolution`).
 
 ## Services
 

src/ClaudeDo.Ui/Design/Tokens.axaml

@@ -104,8 +104,9 @@
   <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="MergeConflictEdgeBrush" Color="#80C87060" /> <!-- unresolved conflict gutter edge / map tick -->
   <SolidColorBrush x:Key="MergeResolvedTintBrush" Color="#206FA86B" /> <!-- resolved conflict (green) -->
+  <SolidColorBrush x:Key="MergeResolvedEdgeBrush" Color="#806FA86B" /> <!-- resolved conflict map tick -->
   <SolidColorBrush x:Key="AmberBrush"             Color="#FFD4A574" /> <!-- solid amber (theirs label) -->
 
   <!-- Window-body gradient layers (apply as LinearGradientBrush in the main content Border) -->

src/ClaudeDo.Ui/ViewModels/Islands/MergeSectionViewModel.cs

@@ -156,6 +156,7 @@ public sealed partial class MergeSectionViewModel : ViewModelBase
                 TaskTitle = TaskTitle ?? "",
                 ShowMergeModal = ShowMergeModal,
                 ResolveMergeVm = () => _services.GetRequiredService<MergeModalViewModel>(),
+                RequestConflictResolution = RequestConflictResolution,
             };
         }
         else if (CanDiffMergedRange)

src/ClaudeDo.Ui/ViewModels/Modals/DiffModalViewModel.cs

@@ -72,6 +72,7 @@ public sealed partial class DiffModalViewModel : ViewModelBase
     public string TaskTitle { get; init; } = "";
     public Func<MergeModalViewModel, Task>? ShowMergeModal { get; set; }
     public Func<MergeModalViewModel>? ResolveMergeVm { get; set; }
+    public Func<string, string, Task>? RequestConflictResolution { get; set; }
 
     public ObservableCollection<DiffFileViewModel> Files { get; } = new();
 
@@ -99,10 +100,11 @@ public sealed partial class DiffModalViewModel : ViewModelBase
     {
         if (TaskId is null || ShowMergeModal is null || ResolveMergeVm is null) return;
         var vm = ResolveMergeVm();
+        vm.RequestConflictResolution = RequestConflictResolution;
         await vm.InitializeAsync(TaskId, TaskTitle);
         await ShowMergeModal(vm);
-        // The diff is stale once the worktree has been merged away — close it too.
+        // The diff is stale once the worktree merged away or a conflict opened the editor.
-        if (vm.Merged) CloseAction?.Invoke();
+        if (vm.Merged || vm.RoutedToResolver) CloseAction?.Invoke();
     }
 
     public async Task LoadAsync(CancellationToken ct = default)

src/ClaudeDo.Ui/ViewModels/Modals/MergeModalViewModel.cs

@@ -28,10 +28,17 @@ public sealed partial class MergeModalViewModel : ViewModelBase
 
     public Action? CloseAction { get; set; }
 
+    /// Set by the caller to hand a conflicting merge off to the in-app 3-pane editor
+    /// instead of dead-ending on the conflict message.
+    public Func<string, string, Task>? RequestConflictResolution { get; set; }
+
     /// True once a merge has succeeded — lets the caller (e.g. the diff window)
     /// close itself after this modal closes.
     public bool Merged { get; private set; }
 
+    /// True once a conflict has been handed off to the resolver — also a cue to close the diff window.
+    public bool RoutedToResolver { get; private set; }
+
     public MergeModalViewModel(IWorkerClient worker)
     {
         _worker = worker;
@@ -96,9 +103,21 @@ public sealed partial class MergeModalViewModel : ViewModelBase
                     });
                     break;
                 case "conflict":
-                    HasConflict = true;
+                    // Hand off to the in-app 3-pane merge editor when wired (MergeTask aborted
-                    ConflictFiles = result.ConflictFiles;
+                    // cleanly, so the resolver re-starts the merge leaving conflicts in the tree).
-                    ErrorMessage = Loc.T("vm.merge.conflict");
+                    if (RequestConflictResolution is not null)
+                    {
+                        var branch = SelectedBranch!;
+                        RoutedToResolver = true;
+                        CloseAction?.Invoke();
+                        await RequestConflictResolution(TaskId, branch);
+                    }
+                    else
+                    {
+                        HasConflict = true;
+                        ConflictFiles = result.ConflictFiles;
+                        ErrorMessage = Loc.T("vm.merge.conflict");
+                    }
                     break;
                 case "blocked":
                     ErrorMessage = Loc.T("vm.merge.blocked", result.ErrorMessage ?? "");

src/ClaudeDo.Ui/Views/Conflicts/ConflictResolverView.axaml

@@ -149,6 +149,9 @@
             <Border Classes="col-head" DockPanel.Dock="Top">
               <TextBlock Classes="eyebrow" Text="{loc:Tr conflictResolver.result}"/>
             </Border>
+            <Canvas Name="ConflictMap" DockPanel.Dock="Right" Width="13"
+                    Background="{DynamicResource Surface2Brush}"
+                    ToolTip.Tip="{loc:Tr conflictResolver.conflictMap}"/>
             <ae:TextEditor Name="ResultEditor" ShowLineNumbers="True"/>
           </DockPanel>
         </Border>

src/ClaudeDo.Ui/Views/Conflicts/ConflictResolverView.axaml.cs

@@ -6,6 +6,7 @@ using System.Linq;
 using System.Text;
 using Avalonia;
 using Avalonia.Controls;
+using Avalonia.Controls.Shapes;
 using Avalonia.Media;
 using Avalonia.Threading;
 using Avalonia.VisualTree;
@@ -251,6 +252,7 @@ public partial class ConflictResolverView : Window
     private void PositionGutters()
     {
         ClearGutters();
+        PopulateConflictMap();
         if (_vm?.ActiveFile is null) return;
         var tv = ResultEditor.TextArea.TextView;
         if (!tv.VisualLinesValid)
@@ -298,6 +300,47 @@ public partial class ConflictResolverView : Window
         canvas.Children.Add(b);
     }
 
+    // ── Conflict overview ruler (right of the result pane) ───────────────────
+
+    // A proportional map of every conflict in the active file so they're findable in
+    // long files without scrolling; ticks recolor by resolved state and jump on click.
+    private void PopulateConflictMap()
+    {
+        ConflictMap.Children.Clear();
+        if (_vm?.ActiveFile is null || _resultRegions.Count == 0) return;
+        var h = ConflictMap.Bounds.Height;
+        if (h <= 1) return;
+        var doc = ResultEditor.Document;
+        var totalLines = Math.Max(1, doc.LineCount);
+        var unresolved = BrushRes("MergeConflictEdgeBrush", Color.Parse("#80C87060"));
+        var resolved = BrushRes("MergeResolvedEdgeBrush", Color.Parse("#806FA86B"));
+
+        foreach (var region in _resultRegions)
+        {
+            var line = doc.GetLineByOffset(region.Start.Offset).LineNumber;
+            var y = (line - 1) / (double)totalLines * h;
+            var tick = new Rectangle
+            {
+                Width = 9,
+                Height = 4,
+                Fill = region.Block.IsResolved ? resolved : unresolved,
+                Cursor = new Avalonia.Input.Cursor(Avalonia.Input.StandardCursorType.Hand),
+            };
+            Canvas.SetLeft(tick, 2);
+            Canvas.SetTop(tick, Math.Min(h - 4, Math.Max(0, y)));
+            var r = region;
+            tick.PointerPressed += (_, _) => JumpToRegion(r);
+            ConflictMap.Children.Add(tick);
+        }
+    }
+
+    private void JumpToRegion(ResultRegion region)
+    {
+        var line = ResultEditor.Document.GetLineByOffset(region.Start.Offset).LineNumber;
+        ResultEditor.ScrollToLine(line);
+        QueueGutters();
+    }
+
     private static string Tr(string key) => ClaudeDo.Ui.Localization.Loc.T(key);
 
     // ── Synced vertical scroll across the three panes ─────────────────────────
@@ -345,7 +388,7 @@ public partial class ConflictResolverView : Window
     private void ApplyGrammar(string? path)
     {
         if (_registry is null || string.IsNullOrEmpty(path)) return;
-        var ext = Path.GetExtension(path);
+        var ext = System.IO.Path.GetExtension(path);
         if (string.IsNullOrEmpty(ext)) return;
         var language = _registry.GetLanguageByExtension(ext);
         if (language is null) return;