Add opt-in setting to open Cmd-clicked markdown files in cmux viewer

Resources/Localizable.xcstrings

@@ -87714,6 +87714,124 @@
           }
         }
       }
+    },
+    "settings.app.openMarkdownInCmuxViewer": {
+      "extractionState": "manual",
+      "localizations": {
+        "en": {
+          "stringUnit": {
+            "state": "translated",
+            "value": "Open Markdown in cmux Viewer"
+          }
+        },
+        "ja": {
+          "stringUnit": {
+            "state": "translated",
+            "value": "cmux ビューアで Markdown を開く"
+          }
+        },
+        "ko": {
+          "stringUnit": {
+            "state": "translated",
+            "value": "cmux 뷰어에서 Markdown 열기"
+          }
+        },
+        "zh-Hans": {
+          "stringUnit": {
+            "state": "translated",
+            "value": "在 cmux 查看器中打开 Markdown"
+          }
+        },
+        "zh-Hant": {
+          "stringUnit": {
+            "state": "translated",
+            "value": "在 cmux 檢視器中開啟 Markdown"
+          }
+        },
+        "de": {
+          "stringUnit": {
+            "state": "translated",
+            "value": "Markdown im cmux-Viewer öffnen"
+          }
+        },
+        "es": {
+          "stringUnit": {
+            "state": "translated",
+            "value": "Abrir Markdown en el visor cmux"
+          }
+        },
+        "fr": {
+          "stringUnit": {
+            "state": "translated",
+            "value": "Ouvrir Markdown dans la visionneuse cmux"
+          }
+        },
+        "it": {
+          "stringUnit": {
+            "state": "translated",
+            "value": "Apri Markdown nel visualizzatore cmux"
+          }
+        }
+      }
+    },
+    "settings.app.openMarkdownInCmuxViewer.subtitle": {
+      "extractionState": "manual",
+      "localizations": {
+        "en": {
+          "stringUnit": {
+            "state": "translated",
+            "value": "Cmd-clicking .md/.markdown/.mkd/.mdx files opens the cmux markdown viewer panel instead of the preferred editor."
+          }
+        },
+        "ja": {
+          "stringUnit": {
+            "state": "translated",
+            "value": ".md/.markdown/.mkd/.mdx ファイルを Cmd+クリックすると、優先エディタの代わりに cmux マークダウンビューアパネルが開きます。"
+          }
+        },
+        "ko": {
+          "stringUnit": {
+            "state": "translated",
+            "value": ".md/.markdown/.mkd/.mdx 파일을 Cmd+클릭하면 기본 에디터 대신 cmux 마크다운 뷰어 패널이 열립니다."
+          }
+        },
+        "zh-Hans": {
+          "stringUnit": {
+            "state": "translated",
+            "value": "Cmd+点击 .md/.markdown/.mkd/.mdx 文件将打开 cmux 标记查看器面板,而不是使用首选编辑器。"
+          }
+        },
+        "zh-Hant": {
+          "stringUnit": {
+            "state": "translated",
+            "value": "Cmd+點擊 .md/.markdown/.mkd/.mdx 檔案會開啟 cmux Markdown 檢視器面板,而不是使用偏好編輯器。"
+          }
+        },
+        "de": {
+          "stringUnit": {
+            "state": "translated",
+            "value": "Cmd-Klick auf .md/.markdown/.mkd/.mdx-Dateien öffnet das cmux-Markdown-Viewer-Panel statt des bevorzugten Editors."
+          }
+        },
+        "es": {
+          "stringUnit": {
+            "state": "translated",
+            "value": "Hacer Cmd+clic en archivos .md/.markdown/.mkd/.mdx abre el panel del visor de markdown de cmux en lugar del editor preferido."
+          }
+        },
+        "fr": {
+          "stringUnit": {
+            "state": "translated",
+            "value": "Cmd+clic sur les fichiers .md/.markdown/.mkd/.mdx ouvre le panneau de la visionneuse markdown cmux au lieu de l'éditeur préféré."
+          }
+        },
+        "it": {
+          "stringUnit": {
+            "state": "translated",
+            "value": "Cmd+clic sui file .md/.markdown/.mkd/.mdx apre il pannello del visualizzatore markdown cmux invece dell'editor preferito."
+          }
+        }
+      }
     }
   }
 }

Sources/GhosttyTerminalView.swift

@@ -3272,6 +3272,40 @@ class GhosttyApp {
                 #endif
                 return false
             }
+            // Route markdown file URLs into the cmux viewer when the toggle is
+            // on AND the link is local + has no anchor/query. Anything else
+            // (toggle off, hosted file URL, #fragment, ?query, non-markdown,
+            // remote workspace, unreadable file, split creation failure) falls
+            // through to the existing NSWorkspace path below so the default-off
+            // behavior and URL semantics are preserved.
+            let fileURLHost = target.url.host
+            if CmdClickMarkdownRouteSettings.isEnabled(),
+               target.url.isFileURL,
+               target.url.fragment == nil,
+               target.url.query == nil,
+               fileURLHost == nil || fileURLHost?.isEmpty == true || fileURLHost == "localhost",
+               CmdClickMarkdownRouteSettings.isMarkdownPath(target.url.path) {
+                let fileURL = target.url
+                let routed: Bool = performOnMain {
+                    // Remote-surface guard runs before shouldRoute so we never
+                    // stat a local path on the main thread for a remote workspace.
+                    guard let termSurface = surfaceView.terminalSurface,
+                          let workspace = termSurface.owningWorkspace(),
+                          !workspace.isRemoteTerminalSurface(termSurface.id),
+                          CmdClickMarkdownRouteSettings.shouldRoute(path: fileURL.path) else {
+                        return false
+                    }
+                    return workspace.openOrFocusMarkdownSplit(
+                        from: termSurface.id,
+                        filePath: fileURL.path
+                    ) != nil
+                }
+                if routed {
+                    return true
+                }
+                // Fall through to the existing NSWorkspace path below.
+            }
+
             if !BrowserLinkOpenSettings.openTerminalLinksInCmuxBrowser() {
                 #if DEBUG
                 dlog("link.openURL cmuxBrowser=disabled, opening externally url=\(target.url)")
@@ -7846,6 +7880,18 @@ class GhosttyNSView: NSView, NSUserInterfaceValidations {
         )
         #endif
 
+        // Remote-surface guard runs before shouldRoute so we never stat a local
+        // path on the main thread for a remote workspace. When the viewer path
+        // is applicable but split creation fails, fall back to the preferred
+        // editor so the click never silently no-ops.
+        if let termSurface = terminalSurface,
+           let workspace = termSurface.owningWorkspace(),
+           !workspace.isRemoteTerminalSurface(termSurface.id),
+           CmdClickMarkdownRouteSettings.shouldRoute(path: resolution.path),
+           workspace.openOrFocusMarkdownSplit(from: termSurface.id, filePath: resolution.path) != nil {
+            return resolution
+        }
+
         PreferredEditorSettings.open(URL(fileURLWithPath: resolution.path))
         return resolution
     }

Sources/KeyboardShortcutSettingsFileStore.swift

@@ -33,6 +33,7 @@ final class CmuxSettingsFileStore {
         "app.keepWorkspaceOpenWhenClosingLastSurface",
         "app.focusPaneOnFirstClick",
         "app.preferredEditor",
+        "app.openMarkdownInCmuxViewer",
         "app.reorderOnNotification",
         "app.sendAnonymousTelemetry",
         "app.warnBeforeQuit",
@@ -430,6 +431,9 @@ final class CmuxSettingsFileStore {
         if let value = jsonString(section["preferredEditor"]) {
             snapshot.managedUserDefaults[PreferredEditorSettings.key] = .string(value)
         }
+        if let value = jsonBool(section["openMarkdownInCmuxViewer"]) {
+            snapshot.managedUserDefaults[CmdClickMarkdownRouteSettings.key] = .bool(value)
+        }
         if let value = jsonBool(section["reorderOnNotification"]) {
             snapshot.managedUserDefaults[WorkspaceAutoReorderSettings.key] = .bool(value)
         }
@@ -1357,6 +1361,7 @@ final class CmuxSettingsFileStore {
                     "keepWorkspaceOpenWhenClosingLastSurface": !LastSurfaceCloseShortcutSettings.defaultValue,
                     "focusPaneOnFirstClick": PaneFirstClickFocusSettings.defaultEnabled,
                     "preferredEditor": "",
+                    "openMarkdownInCmuxViewer": CmdClickMarkdownRouteSettings.defaultValue,
                     "reorderOnNotification": WorkspaceAutoReorderSettings.defaultValue,
                     "sendAnonymousTelemetry": TelemetrySettings.defaultSendAnonymousTelemetry,
                     "warnBeforeQuit": QuitWarningSettings.defaultWarnBeforeQuit,

Sources/Workspace.swift

@@ -9178,6 +9178,34 @@ final class Workspace: Identifiable, ObservableObject {
         return browserPanel
     }
 
+    /// Open the markdown viewer for `filePath`, reusing an existing
+    /// `MarkdownPanel` in this workspace that already shows the same file.
+    /// Paths are compared after symlink resolution so `./README.md` and a
+    /// symlink pointing at the same file focus the same viewer.
+    /// Returns `nil` when no existing viewer matches and split creation
+    /// fails, so callers can fall back to the preferred editor / system opener.
+    @discardableResult
+    func openOrFocusMarkdownSplit(
+        from panelId: UUID,
+        filePath: String
+    ) -> MarkdownPanel? {
+        let canonical = (filePath as NSString).resolvingSymlinksInPath
+        for (existingId, panel) in panels {
+            guard let md = panel as? MarkdownPanel else { continue }
+            if (md.filePath as NSString).resolvingSymlinksInPath == canonical {
+                focusPanel(existingId)
+                return md
+            }
+        }
+        return newMarkdownSplit(
+            from: panelId,
+            orientation: .horizontal,
+            insertFirst: false,
+            filePath: filePath,
+            focus: true
+        )
+    }
+
     func newMarkdownSplit(
         from panelId: UUID,
         orientation: SplitOrientation,

Sources/cmuxApp.swift

@@ -4128,6 +4128,37 @@ enum TelemetrySettings {
     static let enabledForCurrentLaunch = isEnabled()
 }
 
+enum CmdClickMarkdownRouteSettings {
+    static let key = "openMarkdownInCmuxViewer"
+    static let defaultValue = false
+
+    static func isEnabled(defaults: UserDefaults = .standard) -> Bool {
+        defaults.object(forKey: key) == nil ? defaultValue : defaults.bool(forKey: key)
+    }
+
+    /// Cheap extension check. Safe to call off the main thread before any
+    /// filesystem probe so remote/non-markdown paths can be filtered early.
+    static func isMarkdownPath(_ path: String) -> Bool {
+        let ext = (path as NSString).pathExtension.lowercased()
+        return ext == "md" || ext == "markdown" || ext == "mkd" || ext == "mdx"
+    }
+
+    static func shouldRoute(path: String) -> Bool {
+        guard isEnabled(), isMarkdownPath(path) else { return false }
+        // Match the `markdown.open` socket path: only route real, readable
+        // files. Rejects FIFOs, device nodes, sockets, symlinks to non-regular
+        // targets, and permission-denied paths so the viewer never opens into
+        // an unavailable state.
+        let resolved = (path as NSString).resolvingSymlinksInPath
+        guard FileManager.default.isReadableFile(atPath: resolved),
+              let attrs = try? FileManager.default.attributesOfItem(atPath: resolved),
+              (attrs[.type] as? FileAttributeType) == .typeRegular else {
+            return false
+        }
+        return true
+    }
+}
+
 enum PreferredEditorSettings {
     static let key = "preferredEditorCommand"
 
@@ -4362,6 +4393,7 @@ struct SettingsView: View {
     @AppStorage(TelemetrySettings.sendAnonymousTelemetryKey)
     private var sendAnonymousTelemetry = TelemetrySettings.defaultSendAnonymousTelemetry
     @AppStorage(PreferredEditorSettings.key) private var preferredEditorCommand = ""
+    @AppStorage(CmdClickMarkdownRouteSettings.key) private var openMarkdownInCmuxViewer = CmdClickMarkdownRouteSettings.defaultValue
     @AppStorage("cmuxPortBase") private var cmuxPortBase = 9100
     @AppStorage("cmuxPortRange") private var cmuxPortRange = 10
     @AppStorage(BrowserSearchSettings.searchEngineKey) private var browserSearchEngine = BrowserSearchSettings.defaultSearchEngine.rawValue
@@ -5068,6 +5100,21 @@ struct SettingsView: View {
 
                         SettingsCardDivider()
 
+                        SettingsCardRow(
+                            configurationReview: .json("app.openMarkdownInCmuxViewer"),
+                            String(localized: "settings.app.openMarkdownInCmuxViewer", defaultValue: "Open Markdown in cmux Viewer"),
+                            subtitle: String(localized: "settings.app.openMarkdownInCmuxViewer.subtitle", defaultValue: "Cmd-clicking .md/.markdown/.mkd/.mdx files opens the cmux markdown viewer panel instead of the preferred editor.")
+                        ) {
+                            Toggle("", isOn: $openMarkdownInCmuxViewer)
+                                .labelsHidden()
+                                .controlSize(.small)
+                                .accessibilityLabel(
+                                    String(localized: "settings.app.openMarkdownInCmuxViewer", defaultValue: "Open Markdown in cmux Viewer")
+                                )
+                        }
+
+                        SettingsCardDivider()
+
                         SettingsCardRow(
                             configurationReview: .json("app.reorderOnNotification"),
                             String(localized: "settings.app.reorderOnNotification", defaultValue: "Reorder on Notification"),
@@ -6479,6 +6526,7 @@ struct SettingsView: View {
         geminiHooksEnabled = GeminiIntegrationSettings.defaultHooksEnabled
         sendAnonymousTelemetry = TelemetrySettings.defaultSendAnonymousTelemetry
         preferredEditorCommand = ""
+        openMarkdownInCmuxViewer = CmdClickMarkdownRouteSettings.defaultValue
         browserSearchEngine = BrowserSearchSettings.defaultSearchEngine.rawValue
         browserSearchSuggestionsEnabled = BrowserSearchSettings.defaultSearchSuggestionsEnabled
         browserThemeMode = BrowserThemeSettings.defaultMode.rawValue