Use Ghostty theme picker for cmux themes

CLI/cmux.swift

@@ -4281,8 +4281,11 @@ struct CMUXCLI {
                    cmux themes set --dark <theme> [--light <theme>]
                    cmux themes clear
 
-            List bundled and discovered Ghostty themes, show the current cmux light/dark
-            theme defaults, and update the default theme override used by cmux.
+            When run in a TTY, `cmux themes` opens an interactive theme picker with
+            live app preview. Use `cmux themes list` for a plain listing.
+
+            The picker previews the selected theme across the running cmux app and
+            lets you apply it to the light theme, dark theme, or both defaults.
 
             Commands:
               list                      List available themes and mark the current light/dark defaults
@@ -4293,6 +4296,7 @@ struct CMUXCLI {
 
             Examples:
               cmux themes
+              cmux themes list
               cmux themes set "Catppuccin Mocha"
               cmux themes set --light "Catppuccin Latte" --dark "Catppuccin Mocha"
               cmux themes clear
@@ -5380,8 +5384,145 @@ struct CMUXCLI {
         let targetBundleIdentifier: String
     }
 
+    private enum ThemePickerTargetMode: String {
+        case both
+        case light
+        case dark
+    }
+
+    private func shouldUseInteractiveThemePicker(jsonOutput: Bool) -> Bool {
+        guard !jsonOutput else { return false }
+        return isatty(STDIN_FILENO) == 1 && isatty(STDOUT_FILENO) == 1
+    }
+
+    private func runInteractiveThemes() throws {
+        guard let helperURL = bundledHelperURL(named: "ghostty") else {
+            throw CLIError(message: "Bundled Ghostty theme picker helper not found")
+        }
+
+        let selection = currentThemeSelection()
+        var environment = ProcessInfo.processInfo.environment
+        environment["CMUX_THEME_PICKER_CONFIG"] = try cmuxThemeOverrideConfigURL().path
+        environment["CMUX_THEME_PICKER_BUNDLE_ID"] = currentCmuxAppBundleIdentifier() ?? Self.cmuxThemeOverrideBundleIdentifier
+        environment["CMUX_THEME_PICKER_TARGET"] = defaultThemePickerTargetMode(current: selection).rawValue
+        if let light = selection.light {
+            environment["CMUX_THEME_PICKER_INITIAL_LIGHT"] = light
+        }
+        if let dark = selection.dark {
+            environment["CMUX_THEME_PICKER_INITIAL_DARK"] = dark
+        }
+        if let resourcesURL = bundledGhosttyResourcesURL() {
+            environment["GHOSTTY_RESOURCES_DIR"] = resourcesURL.path
+        }
+
+        let process = Process()
+        process.executableURL = helperURL
+        process.arguments = ["+list-themes"]
+        process.environment = environment
+        process.standardInput = FileHandle.standardInput
+        process.standardOutput = FileHandle.standardOutput
+        process.standardError = FileHandle.standardError
+        try process.run()
+        process.waitUntilExit()
+
+        guard process.terminationReason == .exit else {
+            throw CLIError(message: "Interactive theme picker terminated unexpectedly")
+        }
+        guard process.terminationStatus == 0 else {
+            throw CLIError(message: "Interactive theme picker failed with status \(process.terminationStatus)")
+        }
+    }
+
+    private func defaultThemePickerTargetMode(current: ThemeSelection) -> ThemePickerTargetMode {
+        if let light = current.light,
+           let dark = current.dark,
+           light.caseInsensitiveCompare(dark) == .orderedSame {
+            return .both
+        }
+        return defaultAppearancePrefersDarkThemes() ? .dark : .light
+    }
+
+    private func defaultAppearancePrefersDarkThemes() -> Bool {
+        let globalDefaults = UserDefaults.standard.persistentDomain(forName: UserDefaults.globalDomain)
+        let interfaceStyle = (globalDefaults?["AppleInterfaceStyle"] as? String)?.trimmingCharacters(in: .whitespacesAndNewlines)
+        return interfaceStyle?.caseInsensitiveCompare("Dark") == .orderedSame
+    }
+
+    private func bundledHelperURL(named helperName: String) -> URL? {
+        let fileManager = FileManager.default
+        guard let executableURL = resolvedExecutableURL() else { return nil }
+
+        var candidates: [URL] = [
+            executableURL.deletingLastPathComponent().appendingPathComponent(helperName, isDirectory: false)
+        ]
+
+        var current = executableURL.deletingLastPathComponent().standardizedFileURL
+        while true {
+            if current.lastPathComponent == "Contents" {
+                candidates.append(
+                    current
+                        .appendingPathComponent("Resources", isDirectory: true)
+                        .appendingPathComponent("bin", isDirectory: true)
+                        .appendingPathComponent(helperName, isDirectory: false)
+                )
+            }
+
+            let projectMarker = current.appendingPathComponent("GhosttyTabs.xcodeproj/project.pbxproj", isDirectory: false)
+            let repoHelper = current
+                .appendingPathComponent("ghostty", isDirectory: true)
+                .appendingPathComponent("zig-out", isDirectory: true)
+                .appendingPathComponent("bin", isDirectory: true)
+                .appendingPathComponent(helperName, isDirectory: false)
+            if fileManager.fileExists(atPath: projectMarker.path),
+               fileManager.isExecutableFile(atPath: repoHelper.path) {
+                candidates.append(repoHelper)
+                break
+            }
+
+            guard let parent = parentSearchURL(for: current) else { break }
+            current = parent
+        }
+
+        return candidates.first(where: { fileManager.isExecutableFile(atPath: $0.path) })
+    }
+
+    private func bundledGhosttyResourcesURL() -> URL? {
+        let fileManager = FileManager.default
+        guard let executableURL = resolvedExecutableURL() else { return nil }
+
+        var current = executableURL.deletingLastPathComponent().standardizedFileURL
+        while true {
+            if current.lastPathComponent == "Contents" {
+                let candidate = current
+                    .appendingPathComponent("Resources", isDirectory: true)
+                    .appendingPathComponent("ghostty", isDirectory: true)
+                if fileManager.fileExists(atPath: candidate.path) {
+                    return candidate
+                }
+            }
+
+            let projectMarker = current.appendingPathComponent("GhosttyTabs.xcodeproj/project.pbxproj", isDirectory: false)
+            let repoResources = current
+                .appendingPathComponent("Resources", isDirectory: true)
+                .appendingPathComponent("ghostty", isDirectory: true)
+            if fileManager.fileExists(atPath: projectMarker.path),
+               fileManager.fileExists(atPath: repoResources.path) {
+                return repoResources
+            }
+
+            guard let parent = parentSearchURL(for: current) else { break }
+            current = parent
+        }
+
+        return Bundle.main.resourceURL?.appendingPathComponent("ghostty", isDirectory: true)
+    }
+
     private func runThemes(commandArgs: [String], jsonOutput: Bool) throws {
         if commandArgs.isEmpty {
+            if shouldUseInteractiveThemePicker(jsonOutput: jsonOutput) {
+                try runInteractiveThemes()
+                return
+            }
             try printThemesList(jsonOutput: jsonOutput)
             return
         }

docs/ghostty-fork.md

@@ -86,6 +86,20 @@ touch the same stale-frame mitigation path and tend to conflict in the same file
 
 The fork branch HEAD is now the section 6 zsh redraw commit.
 
+### 7) cmux theme picker helper hooks
+
+- Commit: `0c52c987b` (Add cmux theme picker helper hooks)
+- Files:
+  - `build.zig`
+  - `src/cli/list_themes.zig`
+  - `src/main_ghostty.zig`
+- Summary:
+  - Adds a `zig build cli-helper` step so cmux can bundle Ghostty's CLI helper binary on macOS.
+  - Lets `+list-themes` switch into a cmux-managed mode via env vars, writing the cmux theme override file and posting the existing cmux reload notification for live app-wide preview.
+  - Fixes the helper-only `app-runtime=none` stdout path so the Ghostty CLI binary builds with the current Zig toolchain.
+
+The fork branch HEAD is now the section 7 cmux theme picker helper commit.
+
 ## Upstreamed fork changes
 
 ### cursor-click-to-move respects OSC 133 click-to-move
@@ -109,4 +123,9 @@ These files change frequently upstream; be careful when rebasing the fork:
     `OSC 133;A` vs `OSC 133;P` split intact for redraw-heavy themes. Pure-style `\n%{\r%}`
     prompt newlines should not get an extra explicit continuation marker after the hidden CR.
 
+- `src/cli/list_themes.zig`
+  - cmux now relies on the upstream picker UI plus local env-driven hooks for live preview and restore.
+    If upstream reorganizes the preview loop or key handling, re-check the cmux mode path and keep the
+    stock Ghostty behavior unchanged when the cmux env vars are absent.
+
 If you resolve a conflict, update this doc with what changed.

ghostty

@@ -1 +1 @@
-Subproject commit 312c7b23a7c8dc0704431940d76ba5dc32a46afb
+Subproject commit 0c52c987be769f244c740b305033a2ec9d85b982

scripts/reload.sh

@@ -306,15 +306,25 @@ else
 fi
 sleep 0.3
 CMUXD_SRC="$PWD/cmuxd/zig-out/bin/cmuxd"
+GHOSTTY_HELPER_SRC="$PWD/ghostty/zig-out/bin/ghostty"
 if [[ -d "$PWD/cmuxd" ]]; then
   (cd "$PWD/cmuxd" && zig build -Doptimize=ReleaseFast)
 fi
+if [[ -d "$PWD/ghostty" ]]; then
+  (cd "$PWD/ghostty" && zig build cli-helper -Dapp-runtime=none -Demit-macos-app=false -Demit-xcframework=false -Doptimize=ReleaseFast)
+fi
 if [[ -x "$CMUXD_SRC" ]]; then
   BIN_DIR="$APP_PATH/Contents/Resources/bin"
   mkdir -p "$BIN_DIR"
   cp "$CMUXD_SRC" "$BIN_DIR/cmuxd"
   chmod +x "$BIN_DIR/cmuxd"
 fi
+if [[ -x "$GHOSTTY_HELPER_SRC" ]]; then
+  BIN_DIR="$APP_PATH/Contents/Resources/bin"
+  mkdir -p "$BIN_DIR"
+  cp "$GHOSTTY_HELPER_SRC" "$BIN_DIR/ghostty"
+  chmod +x "$BIN_DIR/ghostty"
+fi
 CLI_PATH="$APP_PATH/Contents/Resources/bin/cmux"
 if [[ -x "$CLI_PATH" ]]; then
   echo "$CLI_PATH" > /tmp/cmux-last-cli-path || true