feat: configurable merge command with squash + delete-branch default

Merge button now runs a configurable command template from settings
(default: `gh pr merge ${number} --squash --delete-branch`).

Adds PR Merge section to General settings with a text field for the
command, supporting ${number} substitution. Includes reset to default.

Author: rogeriochaves

Sources/KanbanCode/CardDetailView.swift

@@ -1127,7 +1127,8 @@ struct CardDetailView: View {
             mergeError = nil
             Task {
                 let gh = GhCliAdapter()
-                let result = try await gh.mergePR(repoRoot: repoRoot, prNumber: pr.number)
+                let settings = try await SettingsStore().read()
+                let result = try await gh.mergePR(repoRoot: repoRoot, prNumber: pr.number, commandTemplate: settings.github.mergeCommand)
                 isMerging = false
                 switch result {
                 case .success:

Sources/KanbanCode/SettingsView.swift

@@ -129,6 +129,8 @@ struct GeneralSettingsView: View {
     @AppStorage("preferredEditorBundleId") private var editorBundleId: String = "dev.zed.Zed"
     @State private var installedEditors: [EditorDiscovery.Editor] = []
     @State private var showOnboarding = false
+    @State private var mergeCommand: String = GitHubSettings.defaultMergeCommand
+    @State private var mergeSaveTask: Task<Void, Never>?
 
     private let settingsStore = SettingsStore()
 
@@ -175,6 +177,24 @@ struct GeneralSettingsView: View {
                 statusRow("Mutagen", available: mutagenAvailable)
             }
 
+            Section("PR Merge") {
+                TextField("Merge command", text: $mergeCommand)
+                    .textFieldStyle(.roundedBorder)
+                    .font(.system(.caption, design: .monospaced))
+                    .onChange(of: mergeCommand) { scheduleMergeSave() }
+                Text("Use ${number} for the PR number. Default: \(GitHubSettings.defaultMergeCommand)")
+                    .font(.caption)
+                    .foregroundStyle(.tertiary)
+                HStack {
+                    Spacer()
+                    Button("Reset to Default") {
+                        mergeCommand = GitHubSettings.defaultMergeCommand
+                        scheduleMergeSave()
+                    }
+                    .controlSize(.small)
+                }
+            }
+
             Section("Settings File") {
                 HStack {
                     Text("~/.kanban-code/settings.json")
@@ -201,6 +221,11 @@ struct GeneralSettingsView: View {
         .onAppear {
             installedEditors = EditorDiscovery.installedEditors()
         }
+        .task {
+            if let settings = try? await settingsStore.read() {
+                mergeCommand = settings.github.mergeCommand
+            }
+        }
         .sheet(isPresented: $showOnboarding) {
             OnboardingWizard(
                 settingsStore: settingsStore,
@@ -212,6 +237,19 @@ struct GeneralSettingsView: View {
         }
     }
 
+    private func scheduleMergeSave() {
+        mergeSaveTask?.cancel()
+        mergeSaveTask = Task {
+            try? await Task.sleep(for: .milliseconds(500))
+            guard !Task.isCancelled else { return }
+            do {
+                var settings = try await settingsStore.read()
+                settings.github.mergeCommand = mergeCommand.isEmpty ? GitHubSettings.defaultMergeCommand : mergeCommand
+                try await settingsStore.write(settings)
+            } catch {}
+        }
+    }
+
     private func statusRow(_ name: String, available: Bool) -> some View {
         HStack {
             Label(name, systemImage: available ? "checkmark.circle.fill" : "minus.circle")

Sources/KanbanCodeCore/Adapters/Git/GhCliAdapter.swift

@@ -388,11 +388,20 @@ public final class GhCliAdapter: PRTrackerPort, @unchecked Sendable {
         }
     }
 
-    /// Merge a PR (respects repo's default merge strategy).
-    public func mergePR(repoRoot: String, prNumber: Int) async throws -> MergeResult {
+    /// Merge a PR using the configured merge command template.
+    /// The template can contain `${number}` which gets replaced with the PR number.
+    public func mergePR(repoRoot: String, prNumber: Int, commandTemplate: String) async throws -> MergeResult {
+        let expanded = commandTemplate.replacingOccurrences(of: "${number}", with: "\(prNumber)")
+        let parts = expanded.components(separatedBy: " ").filter { !$0.isEmpty }
+        guard parts.count >= 2 else { return .failure("Invalid merge command") }
+
+        // Resolve the executable (first part, e.g. "gh")
+        let executable = ShellCommand.findExecutable(parts[0]) ?? parts[0]
+        let arguments = Array(parts.dropFirst())
+
         let result = try await ShellCommand.run(
-            ghPath,
-            arguments: ["pr", "merge", "\(prNumber)"],
+            executable,
+            arguments: arguments,
             currentDirectory: repoRoot
         )
         if result.succeeded {

Sources/KanbanCodeCore/Infrastructure/SettingsStore.swift

@@ -88,10 +88,14 @@ public struct GlobalViewSettings: Codable, Sendable {
 public struct GitHubSettings: Codable, Sendable {
     public var defaultFilter: String
     public var pollIntervalSeconds: Int
+    public var mergeCommand: String
 
-    public init(defaultFilter: String = "assignee:@me is:open", pollIntervalSeconds: Int = 60) {
+    public static let defaultMergeCommand = "gh pr merge ${number} --squash --delete-branch"
+
+    public init(defaultFilter: String = "assignee:@me is:open", pollIntervalSeconds: Int = 60, mergeCommand: String? = nil) {
         self.defaultFilter = defaultFilter
         self.pollIntervalSeconds = pollIntervalSeconds
+        self.mergeCommand = mergeCommand ?? Self.defaultMergeCommand
     }
 }