Custom sidebars: in-process renderer by default, Settings section, worker resize pump fix

.github/swift-file-length-budget.tsv

@@ -4,7 +4,7 @@
 32955	CLI/cmux.swift
 22576	Sources/TerminalController.swift
 19955	Sources/Workspace.swift
-19248	Sources/ContentView.swift
+19256	Sources/ContentView.swift
 18057	Sources/AppDelegate.swift
 16539	Sources/GhosttyTerminalView.swift
 13608	Sources/Panels/BrowserPanel.swift
@@ -127,7 +127,7 @@
 683	Sources/Panels/CodexAppServerSession.swift
 681	Sources/Panels/AgentSessionProcessStore.swift
 680	Sources/FileExplorerSearchController.swift
-669	Packages/CmuxSwiftRender/Sources/CmuxSwiftRender/SwiftViewInterpreter.swift
+683	Packages/CmuxSwiftRender/Sources/CmuxSwiftRender/SwiftViewInterpreter.swift
 668	cmuxTests/FeedCoordinatorTests.swift
 668	cmuxTests/KeyboardShortcutContextTests.swift
 654	Packages/CmuxSettingsUI/Sources/CmuxSettingsUI/Sections/KeyboardShortcutsSection.swift
@@ -146,7 +146,7 @@
 596	cmuxTests/CmuxEventBusTests.swift
 594	Sources/SessionIndexModels.swift
 594	cmuxTests/PortalTabDragRoutingTests.swift
-589	Sources/SettingsNavigation.swift
+599	Sources/SettingsNavigation.swift
 588	cmuxTests/CommandPaletteShortcutCustomizationTests.swift
 586	Sources/JSONCParser.swift
 585	Sources/Cloud/VMClient.swift
@@ -170,7 +170,7 @@
 528	cmuxTests/CLINotifyProcessTestSupport.swift
 528	cmuxUITests/AutomationSocketUITests.swift
 527	CLI/CLISocketPathResolver.swift
-523	Packages/CmuxSettingsUI/Sources/CmuxSettingsUI/Scene/SettingsWindowScene.swift
+531	Packages/CmuxSettingsUI/Sources/CmuxSettingsUI/Scene/SettingsWindowScene.swift
 522	Packages/CmuxMobileTerminal/Sources/CmuxMobileTerminal/GhosttyRuntime.swift
 520	CLI/CMUXCLI+AmpExtension.swift
 520	cmuxTests/MainWindowVisibilityControllerTests.swift

CLI/CMUXCLI+DocsSettings.swift

@@ -369,9 +369,10 @@ extension CMUXCLI {
           docs                Print the same output as `cmux docs settings`.
 
         Targets:
-          account, app, terminal, sidebar-appearance, automation, browser,
-          browser-import, global-hotkey, keyboard-shortcuts, shortcuts,
-          workspace-colors, cmux-json, json, reset
+          account, app, terminal, sidebar-appearance, custom-sidebars,
+          automation, browser, browser-import, global-hotkey,
+          keyboard-shortcuts, shortcuts, workspace-colors, cmux-json,
+          json, reset
 
         Config file:
           \(Self.primarySettingsDisplayPath)
@@ -404,6 +405,8 @@ extension CMUXCLI {
             return "terminal"
         case "sidebar", "sidebar-appearance", "sidebarappearance":
             return "sidebarAppearance"
+        case "custom-sidebars", "customsidebars":
+            return "customSidebars"
         case "automation":
             return "automation"
         case "browser":

Packages/CmuxSettings/Sources/CmuxSettings/Keys/BetaFeaturesCatalogSection.swift

@@ -38,12 +38,12 @@ public struct BetaFeaturesCatalogSection: SettingCatalogSection {
 
     /// Custom sidebars: user/agent-authored sidebars (interpreted Swift or
     /// JSON) discovered from `~/.config/cmux/sidebars/` and selectable in the
-    /// sidebar button's provider picker. Defaults off; while off, no custom
+    /// sidebar button's provider picker. Defaults on; while off, no custom
     /// sidebar appears in the picker and a persisted custom selection falls
     /// back to the default workspaces sidebar.
     public let customSidebars = DefaultsKey<Bool>(
         id: "customSidebars.beta.enabled",
-        defaultValue: false,
+        defaultValue: true,
         userDefaultsKey: "customSidebars.beta.enabled"
     )
 

Packages/CmuxSettings/Sources/CmuxSettings/Keys/CustomSidebarsCatalogSection.swift

@@ -0,0 +1,23 @@
+import Foundation
+
+/// Settings for custom (user/agent-authored) sidebars, the `customSidebars.*`
+/// keys. The beta gate that lists custom sidebars in the picker lives in
+/// ``BetaFeaturesCatalogSection/customSidebars``; this section holds how a
+/// selected custom sidebar behaves.
+public struct CustomSidebarsCatalogSection: SettingCatalogSection {
+    /// Which renderer a selected custom sidebar uses: `inProcess` (default;
+    /// native in-host SwiftUI with real hover/focus/keyboard) or `remote`
+    /// (the crash-isolated out-of-process worker for untrusted sources).
+    ///
+    /// JSON-backed so it can be flipped by editing `~/.config/cmux/cmux.json`:
+    ///
+    /// ```json
+    /// { "customSidebars": { "renderer": "remote" } }
+    /// ```
+    public let renderer = JSONKey<CustomSidebarRendererMode>(
+        id: "customSidebars.renderer",
+        defaultValue: .inProcess
+    )
+
+    public init() {}
+}

Packages/CmuxSettings/Sources/CmuxSettings/Keys/SettingCatalog.swift

@@ -37,6 +37,8 @@ public struct SettingCatalog: SettingCatalogSection {
     /// Settings for Mobile pairing and sync.
     public let mobile = MobileCatalogSection()
     public let betaFeatures = BetaFeaturesCatalogSection()
+    /// Settings for custom (user/agent-authored) sidebars (the `customSidebars.*` keys).
+    public let customSidebars = CustomSidebarsCatalogSection()
     public let shortcuts = KeyboardShortcutsCatalogSection()
     public let integrations = IntegrationsCatalogSection()
     public let account = AccountCatalogSection()

Packages/CmuxSettings/Sources/CmuxSettings/Values/CustomSidebarRendererMode.swift

@@ -0,0 +1,20 @@
+import Foundation
+
+/// Where a custom sidebar's interpreted source is rendered.
+///
+/// Stored under the catalog entry ``CustomSidebarsCatalogSection/renderer``
+/// (`customSidebars.renderer` in `~/.config/cmux/cmux.json`). The raw values
+/// are the on-disk strings, so they must not be renamed without a migration.
+public enum CustomSidebarRendererMode: String, CaseIterable, Sendable, SettingCodable {
+    /// The containment lane: an out-of-process render worker
+    /// interprets and renders the file; the host only composites the worker's
+    /// remote layer, so an interpreter fault cannot crash the host. Input is
+    /// limited to forwarded clicks (no hover, focus, or keyboard).
+    case remote
+
+    /// The default lane: the file is interpreted and rendered as real
+    /// SwiftUI in the host process, gaining native input (hover, focus,
+    /// keyboard) and same-frame resize. A renderer fault shares the host
+    /// process, so only use this for sidebars you authored yourself.
+    case inProcess
+}

Packages/CmuxSettings/Tests/CmuxSettingsTests/CustomSidebarRendererSettingTests.swift

@@ -0,0 +1,52 @@
+import Foundation
+import Testing
+@testable import CmuxSettings
+
+/// Behavior of the `customSidebars.renderer` setting through the real JSON
+/// store: the on-disk strings users put in `~/.config/cmux/cmux.json` must
+/// decode to the right renderer, and anything else must fall back to the
+/// default (native in-process rendering).
+@Suite("customSidebars.renderer")
+struct CustomSidebarRendererSettingTests {
+    private func makeStore() -> (JSONConfigStore, URL) {
+        let tempDir = FileManager.default.temporaryDirectory
+            .appendingPathComponent("cmux-renderer-tests-\(UUID().uuidString)", isDirectory: true)
+        try? FileManager.default.createDirectory(at: tempDir, withIntermediateDirectories: true)
+        let fileURL = tempDir.appendingPathComponent("cmux.json", isDirectory: false)
+        return (JSONConfigStore(fileURL: fileURL), fileURL)
+    }
+
+    @Test func defaultsToInProcessWhenUnset() async {
+        let (store, _) = makeStore()
+        let value = await store.value(for: SettingCatalog().customSidebars.renderer)
+        #expect(value == .inProcess)
+    }
+
+    @Test func readsRemoteFromHandEditedConfigFile() async throws {
+        let (store, fileURL) = makeStore()
+        try #"{ "customSidebars": { "renderer": "remote" } }"#
+            .write(to: fileURL, atomically: true, encoding: .utf8)
+        let value = await store.value(for: SettingCatalog().customSidebars.renderer)
+        #expect(value == .remote)
+    }
+
+    @Test func unknownRawValueFallsBackToTheDefault() async throws {
+        let (store, fileURL) = makeStore()
+        try #"{ "customSidebars": { "renderer": "yolo" } }"#
+            .write(to: fileURL, atomically: true, encoding: .utf8)
+        let value = await store.value(for: SettingCatalog().customSidebars.renderer)
+        #expect(value == .inProcess)
+    }
+
+    @Test func roundTripsThroughTheStore() async throws {
+        let (store, fileURL) = makeStore()
+        try await store.set(.remote, for: SettingCatalog().customSidebars.renderer)
+        let value = await store.value(for: SettingCatalog().customSidebars.renderer)
+        #expect(value == .remote)
+
+        // The on-disk representation is the raw string, hand-editable.
+        let parsed = try JSONSerialization.jsonObject(with: Data(contentsOf: fileURL)) as? [String: Any]
+        let section = parsed?["customSidebars"] as? [String: Any]
+        #expect(section?["renderer"] as? String == "remote")
+    }
+}

Packages/CmuxSettingsUI/Sources/CmuxSettingsUI/Navigation/CuratedSettingEntry+Default.swift

@@ -102,6 +102,10 @@ extension Array where Element == CuratedSettingEntry {
             .init(section: .mobile, id: "iOSPairingPort", title: String(localized: "settings.mobile.port", defaultValue: "Pairing Port"), synonyms: "mobile.iOSPairingHost.port ios iphone mobile pairing port tcp listener firewall conflict"),
             .init(section: .mobile, id: "iOSPairingDisplayName", title: String(localized: "settings.mobile.displayName", defaultValue: "Display Name"), synonyms: "mobile.iOSPairingHost.displayName ios iphone mobile pairing display name mac hostname device label"),
 
+            // Custom Sidebars
+            .init(section: .customSidebars, id: "enabled", title: String(localized: "settings.customSidebars.enabled", defaultValue: "Show Custom Sidebars"), synonyms: "custom sidebars enable show vibe swift json interpreted picker beta"),
+            .init(section: .customSidebars, id: "renderer", title: String(localized: "settings.customSidebars.renderer", defaultValue: "Renderer"), synonyms: "customSidebars.renderer renderer in-process in app remote worker isolated process hover focus typing input"),
+
             // Beta
             .init(section: .betaFeatures, id: "feed", title: "Feed", synonyms: "feed right sidebar agent decisions permissions questions approval beta unstable"),
             .init(section: .betaFeatures, id: "dock", title: "Dock", synonyms: "dock right sidebar terminal controls tui beta unstable"),

Packages/CmuxSettingsUI/Sources/CmuxSettingsUI/Navigation/SettingsSectionID.swift

@@ -17,6 +17,8 @@ public enum SettingsSectionID: String, CaseIterable, Identifiable, Sendable, Has
     /// Mobile pairing and sync settings.
     case mobile
     case sidebarAppearance
+    /// User/agent-authored custom sidebars: enable gate and renderer choice.
+    case customSidebars
     case betaFeatures
     case automation
     case browser
@@ -38,6 +40,7 @@ public enum SettingsSectionID: String, CaseIterable, Identifiable, Sendable, Has
         case .textBox: return String(localized: "settings.section.textBox", defaultValue: "TextBox (Beta)")
         case .mobile: return String(localized: "settings.section.mobile", defaultValue: "Mobile")
         case .sidebarAppearance: return "Sidebar"
+        case .customSidebars: return String(localized: "settings.section.customSidebars", defaultValue: "Custom Sidebars")
         case .betaFeatures: return "Beta Features"
         case .automation: return "Automation"
         case .browser: return "Browser"
@@ -59,6 +62,7 @@ public enum SettingsSectionID: String, CaseIterable, Identifiable, Sendable, Has
         case .textBox: return "textformat"
         case .mobile: return "iphone"
         case .sidebarAppearance: return "sidebar.left"
+        case .customSidebars: return "sidebar.squares.left"
         case .betaFeatures: return "exclamationmark.triangle"
         case .automation: return "wand.and.sparkles"
         case .browser: return "globe"
@@ -82,6 +86,7 @@ public enum SettingsSectionID: String, CaseIterable, Identifiable, Sendable, Has
         case .textBox: return "textbox text box rich input prompt default new terminal workspace split tab focus show beta"
         case .mobile: return "ios iphone ipad mobile pairing local network sync"
         case .sidebarAppearance: return "sidebar details branches material terminal background"
+        case .customSidebars: return "custom sidebars vibe swift json interpreted renderer in-process remote worker isolated"
         case .betaFeatures: return "beta experimental unstable feed dock right sidebar"
         case .automation: return "socket integrations hooks ports claude cursor gemini"
         case .browser: return "search engine links history theme"

Packages/CmuxSettingsUI/Sources/CmuxSettingsUI/Scene/SettingsWindowScene.swift

@@ -462,6 +462,14 @@ public struct SettingsWindowRoot: View {
         SidebarSection(defaultsStore: defaultsStore, catalog: catalog, hostActions: hostActions)
             .id(anchorID(for: .sidebarAppearance))
 
+        CustomSidebarsSection(
+            defaultsStore: defaultsStore,
+            jsonStore: jsonStore,
+            catalog: catalog,
+            errorLog: runtime.errorLog
+        )
+        .id(anchorID(for: .customSidebars))
+
         BetaFeaturesSection(defaultsStore: defaultsStore, catalog: catalog)
             .id(anchorID(for: .betaFeatures))
 

Packages/CmuxSettingsUI/Sources/CmuxSettingsUI/Sections/CustomSidebarsSection.swift

@@ -0,0 +1,77 @@
+import CmuxSettings
+import SwiftUI
+
+/// **Custom Sidebars** section — the user/agent-authored sidebar
+/// surface: the enable toggle (shared with the Beta Features gate) and
+/// the renderer picker choosing between the crash-isolated helper
+/// process and native in-app rendering.
+@MainActor
+public struct CustomSidebarsSection: View {
+    @State private var enabled: DefaultsValueModel<Bool>
+    @State private var renderer: JSONValueModel<CustomSidebarRendererMode>
+
+    public init(
+        defaultsStore: UserDefaultsSettingsStore,
+        jsonStore: JSONConfigStore,
+        catalog: SettingCatalog,
+        errorLog: SettingsErrorLog
+    ) {
+        _enabled = State(initialValue: DefaultsValueModel(store: defaultsStore, key: catalog.betaFeatures.customSidebars))
+        _renderer = State(initialValue: JSONValueModel(
+            store: jsonStore,
+            key: catalog.customSidebars.renderer,
+            errorLog: errorLog
+        ))
+    }
+
+    public var body: some View {
+        Group {
+            SettingsSectionHeader(String(localized: "settings.section.customSidebars", defaultValue: "Custom Sidebars"), section: .customSidebars)
+            SettingsCard {
+                enabledRow
+                SettingsCardDivider()
+                rendererRow
+                SettingsCardDivider()
+                SettingsCardNote(
+                    String(localized: "settings.customSidebars.note", defaultValue: "Custom sidebars are SwiftUI-style files in ~/.config/cmux/sidebars. Pick one from the sidebar toggle button's right-click menu; edits hot-reload on save. Use the in-app renderer only for sidebars you trust.")
+                )
+            }
+        }
+    }
+
+    @ViewBuilder
+    private var enabledRow: some View {
+        SettingsCardRow(
+            configurationReview: .settingsOnly,
+            searchAnchorID: "setting:customSidebars:enabled",
+            String(localized: "settings.customSidebars.enabled", defaultValue: "Show Custom Sidebars"),
+            subtitle: enabled.current
+                ? String(localized: "settings.customSidebars.enabled.subtitleOn", defaultValue: "Lists your sidebars from ~/.config/cmux/sidebars in the sidebar picker.")
+                : String(localized: "settings.customSidebars.enabled.subtitleOff", defaultValue: "Hides custom sidebars from the sidebar picker until you enable them here.")
+        ) {
+            Toggle("", isOn: Binding(get: { enabled.current }, set: { enabled.set($0) }))
+                .labelsHidden()
+                .controlSize(.small)
+                .accessibilityIdentifier("SettingsCustomSidebarsEnabledToggle")
+        }
+    }
+
+    @ViewBuilder
+    private var rendererRow: some View {
+        SettingsCardRow(
+            configurationReview: .json("customSidebars.renderer"),
+            String(localized: "settings.customSidebars.renderer", defaultValue: "Renderer"),
+            subtitle: renderer.current.rendererDescription
+        ) {
+            Picker("", selection: Binding(get: { renderer.current }, set: { renderer.set($0) })) {
+                ForEach(CustomSidebarRendererMode.uiCases, id: \.self) { mode in
+                    Text(mode.displayName).tag(mode)
+                }
+            }
+            .labelsHidden()
+            .pickerStyle(.menu)
+            .disabled(!enabled.current)
+            .accessibilityIdentifier("SettingsCustomSidebarsRendererPicker")
+        }
+    }
+}

Packages/CmuxSettingsUI/Sources/CmuxSettingsUI/Values/CustomSidebarRendererMode+Display.swift

@@ -0,0 +1,31 @@
+import CmuxSettings
+import Foundation
+
+/// UI-facing labels for ``CustomSidebarRendererMode``, shown by the
+/// Custom Sidebars settings section's renderer picker.
+extension CustomSidebarRendererMode {
+    /// Canonical UI ordering of the modes in the picker.
+    static var uiCases: [CustomSidebarRendererMode] {
+        [.remote, .inProcess]
+    }
+
+    /// Short label shown in the renderer picker.
+    var displayName: String {
+        switch self {
+        case .remote:
+            return String(localized: "customSidebarRenderer.remote.name", defaultValue: "Isolated process")
+        case .inProcess:
+            return String(localized: "customSidebarRenderer.inProcess.name", defaultValue: "In-app (full input)")
+        }
+    }
+
+    /// One-sentence row subtitle explaining the tradeoff.
+    var rendererDescription: String {
+        switch self {
+        case .remote:
+            return String(localized: "customSidebarRenderer.remote.description", defaultValue: "Renders in a crash-isolated helper process. Clicks only: no hover, focus, or typing.")
+        case .inProcess:
+            return String(localized: "customSidebarRenderer.inProcess.description", defaultValue: "Renders as native SwiftUI inside cmux with hover, focus, and typing. A faulty sidebar shares the app process.")
+        }
+    }
+}

Packages/CmuxSettingsUI/Tests/CmuxSettingsUITests/SettingsRowAnchorResolutionTests.swift

@@ -74,6 +74,7 @@ struct SettingsRowAnchorResolutionTests {
         "browser.showSearchSuggestions",
         "browser.theme",
         "browser.urlsToAlwaysOpenExternally",
+        "customSidebars.renderer",
         "fileEditor.wordWrap",
         "notifications.command",
         "notifications.dockBadge",
@@ -132,6 +133,7 @@ struct SettingsRowAnchorResolutionTests {
         "setting:betaFeatures:feed",
         "setting:betaFeatures:dock",
         "setting:betaFeatures:customSidebars",
+        "setting:customSidebars:enabled",
         "setting:browser:history",
         "setting:browser:http-allowlist",
         "setting:workspaceColors:palette",

Packages/CmuxSidebarInterpreterService/Package.swift

@@ -73,5 +73,12 @@ let package = Package(
                 .swiftLanguageMode(.v6),
             ]
         ),
+        .testTarget(
+            name: "CmuxSidebarRemoteRenderTests",
+            dependencies: ["CmuxSidebarRemoteRender"],
+            swiftSettings: [
+                .swiftLanguageMode(.v6),
+            ]
+        ),
     ]
 )