Fall back for blank sidebar icons

Sources/Panels/PanelContentView.swift

@@ -126,17 +126,25 @@ struct PanelContentView: View {
     }
 }
 
+private let panelFilePathHeaderIconSlotSize: CGFloat = 14
+private let panelFilePathHeaderHorizontalPadding: CGFloat = 6
+private let panelFilePathHeaderContentSpacing: CGFloat = 6
+
 struct PanelFilePathHeader<TrailingContent: View>: View {
     let iconSystemName: String
     let filePath: String
     let foregroundColor: NSColor
     @ViewBuilder let trailingContent: () -> TrailingContent
 
     var body: some View {
-        HStack(spacing: 8) {
+        HStack(spacing: panelFilePathHeaderContentSpacing) {
             Image(systemName: iconSystemName)
+                .font(.system(size: panelFilePathHeaderIconSlotSize))
                 .foregroundStyle(.secondary)
-                .frame(width: 16)
+                .frame(
+                    width: panelFilePathHeaderIconSlotSize,
+                    height: panelFilePathHeaderIconSlotSize
+                )
             Text(filePath)
                 .font(.system(size: 11, design: .monospaced))
                 .foregroundStyle(Color(nsColor: foregroundColor).opacity(0.68))
@@ -146,7 +154,7 @@ struct PanelFilePathHeader<TrailingContent: View>: View {
             Spacer(minLength: 8)
             trailingContent()
         }
-        .padding(.horizontal, 12)
+        .padding(.horizontal, panelFilePathHeaderHorizontalPadding)
         .frame(height: 30)
         .background(Color.clear)
     }

Sources/RenderableSystemSymbol.swift

@@ -0,0 +1,58 @@
+import AppKit
+
+enum RenderableSystemSymbol {
+    static let defaultWorkspaceGroupIcon = "folder.fill"
+    static let defaultSurfaceTabIcon = "doc.text"
+    @MainActor
+    private static var renderabilityCache: [String: Bool] = [:]
+
+    static func trimmed(_ raw: String?) -> String? {
+        guard let trimmed = raw?.trimmingCharacters(in: .whitespacesAndNewlines),
+              !trimmed.isEmpty else {
+            return nil
+        }
+        return trimmed
+    }
+
+    @MainActor
+    static func normalized(_ raw: String?) -> String? {
+        guard let trimmed = trimmed(raw),
+              isRenderable(trimmed) else {
+            return nil
+        }
+        return trimmed
+    }
+
+    @MainActor
+    static func resolvedWorkspaceGroupIcon(explicit: String?, configured: String?) -> String {
+        for candidate in [explicit, configured] {
+            guard let normalized = normalized(candidate) else { continue }
+            return normalized
+        }
+        return defaultWorkspaceGroupIcon
+    }
+
+    @MainActor
+    static func resolvedSurfaceTabIcon(_ raw: String?, fallback: String = defaultSurfaceTabIcon) -> String {
+        normalized(raw)
+            ?? normalized(fallback)
+            ?? defaultSurfaceTabIcon
+    }
+
+    @MainActor
+    static func isRenderable(_ symbol: String) -> Bool {
+        if let cached = renderabilityCache[symbol] {
+            return cached
+        }
+        let resolved = NSImage(systemSymbolName: symbol, accessibilityDescription: nil) != nil
+        renderabilityCache[symbol] = resolved
+        return resolved
+    }
+
+    #if DEBUG
+    @MainActor
+    static func resetRenderabilityCacheForTesting() {
+        renderabilityCache.removeAll()
+    }
+    #endif
+}

Sources/SidebarWorkspaceGroupHeaderView.swift

@@ -74,6 +74,10 @@ struct SidebarWorkspaceGroupHeaderView: View, Equatable {
         return .secondary
     }
 
+    private var displayedIconSymbol: String {
+        RenderableSystemSymbol.resolvedWorkspaceGroupIcon(explicit: iconSymbol, configured: nil)
+    }
+
     private var shortcutHintPillText: String? {
         guard showsShortcutHint,
               let shortcutDigit,
@@ -111,9 +115,11 @@ struct SidebarWorkspaceGroupHeaderView: View, Equatable {
                 )
 
             HStack(spacing: 6) {
-                Image(systemName: iconSymbol)
-                    .font(.system(size: 11))
+                Image(systemName: displayedIconSymbol)
+                    .font(.system(size: 11, weight: .semibold))
                     .foregroundStyle(iconColor)
+                    .frame(width: 14, height: 14)
+                    .accessibilityHidden(true)
                 Text(name)
                     .font(.system(size: 11, weight: .semibold))
                     .foregroundStyle(isAnchorActive ? Color.primary : Color.primary.opacity(0.9))

Sources/TabManager.swift

@@ -6584,10 +6584,13 @@ class TabManager: ObservableObject {
         workspaceGroups[index].customColor = hex
     }
 
-    func setWorkspaceGroupIcon(groupId: UUID, symbol: String?) {
-        guard let index = workspaceGroups.firstIndex(where: { $0.id == groupId }) else { return }
-        guard workspaceGroups[index].iconSymbol != symbol else { return }
-        workspaceGroups[index].iconSymbol = symbol
+    @discardableResult
+    func setWorkspaceGroupIcon(groupId: UUID, symbol: String?) -> String? {
+        let normalized = RenderableSystemSymbol.normalized(symbol)
+        guard let index = workspaceGroups.firstIndex(where: { $0.id == groupId }) else { return nil }
+        guard workspaceGroups[index].iconSymbol != normalized else { return normalized }
+        workspaceGroups[index].iconSymbol = normalized
+        return normalized
     }
 
     /// Reassign which member workspace serves as the group's anchor.

Sources/TerminalController.swift

@@ -6560,12 +6560,15 @@ class TerminalController {
         let symbol: String? = (params["symbol"] as? String).map { $0.trimmingCharacters(in: .whitespacesAndNewlines) }
         let normalized: String? = (symbol?.isEmpty == false) ? symbol : nil
         var ok = false
+        var storedIconSymbol: String?
         v2MainSync {
             ok = tabManager.workspaceGroups.contains(where: { $0.id == gid })
-            if ok { tabManager.setWorkspaceGroupIcon(groupId: gid, symbol: normalized) }
+            if ok {
+                storedIconSymbol = tabManager.setWorkspaceGroupIcon(groupId: gid, symbol: normalized)
+            }
         }
         return ok
-            ? .ok(["group_id": gid.uuidString, "icon_symbol": v2OrNull(normalized)])
+            ? .ok(["group_id": gid.uuidString, "icon_symbol": v2OrNull(storedIconSymbol)])
             : .err(code: "not_found", message: "Group not found", data: ["group_id": gid.uuidString])
     }
 

Sources/VerticalTabsSidebar+WorkspaceGroups.swift

@@ -13,7 +13,10 @@ extension VerticalTabsSidebar {
         let anchorCwd = renderContext.workspaceById[group.anchorWorkspaceId]?.currentDirectory
         let resolvedConfig = cmuxConfigStore.resolveWorkspaceGroupConfig(forCwd: anchorCwd)
         let effectiveColor = group.customColor ?? resolvedConfig?.color
-        let effectiveIcon = group.iconSymbol ?? resolvedConfig?.iconSymbol ?? "folder.fill"
+        let effectiveIcon = RenderableSystemSymbol.resolvedWorkspaceGroupIcon(
+            explicit: group.iconSymbol,
+            configured: resolvedConfig?.iconSymbol
+        )
         let cwdContextMenuItems = resolvedConfig?.contextMenuItems ?? []
         let newWorkspacePlacement = resolvedConfig?.newWorkspacePlacement
         let anchorUnreadCount: Int = {

Sources/Workspace.swift

@@ -11048,8 +11048,9 @@ final class Workspace: Identifiable, ObservableObject {
                 self.panelTitles[filePreviewPanel.id] = newTitle
             }
             let resolvedTitle = self.resolvedPanelTitle(panelId: filePreviewPanel.id, fallback: newTitle)
+            let resolvedIcon = RenderableSystemSymbol.resolvedSurfaceTabIcon(displayIcon)
             let titleUpdate: String? = existing.title == resolvedTitle ? nil : resolvedTitle
-            let iconUpdate: String?? = existing.icon == displayIcon ? nil : .some(displayIcon)
+            let iconUpdate: String?? = existing.icon == resolvedIcon ? nil : .some(resolvedIcon)
             let dirtyUpdate: Bool? = existing.isDirty == isDirty ? nil : isDirty
             guard titleUpdate != nil || iconUpdate != nil || dirtyUpdate != nil else { return }
             self.bonsplitController.updateTab(
@@ -14178,7 +14179,7 @@ final class Workspace: Identifiable, ObservableObject {
 
         guard let newTabId = bonsplitController.createTab(
             title: filePreviewPanel.displayTitle,
-            icon: filePreviewPanel.displayIcon,
+            icon: RenderableSystemSymbol.resolvedSurfaceTabIcon(filePreviewPanel.displayIcon),
             kind: SurfaceKind.filePreview,
             isDirty: filePreviewPanel.isDirty,
             isLoading: false,
@@ -14294,7 +14295,7 @@ final class Workspace: Identifiable, ObservableObject {
 
         let newTab = Bonsplit.Tab(
             title: filePreviewPanel.displayTitle,
-            icon: filePreviewPanel.displayIcon,
+            icon: RenderableSystemSymbol.resolvedSurfaceTabIcon(filePreviewPanel.displayIcon),
             kind: SurfaceKind.filePreview,
             isDirty: filePreviewPanel.isDirty,
             isLoading: false,

cmux.xcodeproj/project.pbxproj

@@ -355,6 +355,7 @@
 		A5001640 /* RemoteRelayZshBootstrap.swift in Sources */ = {isa = PBXBuildFile; fileRef = A5001641 /* RemoteRelayZshBootstrap.swift */; };
 		B9000027A1B2C3D4E5F60719 /* RemoteRelayZshBootstrap.swift in Sources */ = {isa = PBXBuildFile; fileRef = A5001641 /* RemoteRelayZshBootstrap.swift */; };
 		E4321000E4321000E4321001 /* RemoteShellSessionParsing.swift in Sources */ = {isa = PBXBuildFile; fileRef = E4321000E4321000E4321002 /* RemoteShellSessionParsing.swift */; };
+		D5037010000000000000003 /* RenderableSystemSymbol.swift in Sources */ = {isa = PBXBuildFile; fileRef = D5037010000000000000002 /* RenderableSystemSymbol.swift */; };
 		F5410004A1B2C3D4E5F60718 /* RestorableAgentHookProviderHermesTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = F5410005A1B2C3D4E5F60718 /* RestorableAgentHookProviderHermesTests.swift */; };
 		F5410000A1B2C3D4E5F60718 /* RestorableAgentHookProviderResumeTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = F5410001A1B2C3D4E5F60718 /* RestorableAgentHookProviderResumeTests.swift */; };
 		F5410002A1B2C3D4E5F60718 /* RestorableAgentNonInteractiveTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = F5410003A1B2C3D4E5F60718 /* RestorableAgentNonInteractiveTests.swift */; };
@@ -981,6 +982,7 @@
 		D0C0D0C0D0C0D0C0D0C00004 /* RemoteLoopbackRuntimeBridge.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RemoteLoopbackRuntimeBridge.swift; sourceTree = "<group>"; };
 		A5001641 /* RemoteRelayZshBootstrap.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RemoteRelayZshBootstrap.swift; sourceTree = "<group>"; };
 		E4321000E4321000E4321002 /* RemoteShellSessionParsing.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RemoteShellSessionParsing.swift; sourceTree = "<group>"; };
+		D5037010000000000000002 /* RenderableSystemSymbol.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RenderableSystemSymbol.swift; sourceTree = "<group>"; };
 		F5410005A1B2C3D4E5F60718 /* RestorableAgentHookProviderHermesTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RestorableAgentHookProviderHermesTests.swift; sourceTree = "<group>"; };
 		F5410001A1B2C3D4E5F60718 /* RestorableAgentHookProviderResumeTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RestorableAgentHookProviderResumeTests.swift; sourceTree = "<group>"; };
 		F5410003A1B2C3D4E5F60718 /* RestorableAgentNonInteractiveTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RestorableAgentNonInteractiveTests.swift; sourceTree = "<group>"; };
@@ -1421,6 +1423,7 @@
 				C9A57108C9A57108C9A57108 /* SidebarWorkspaceGroupDialogs.swift */,
 				C9A57102C9A57102C9A57102 /* SidebarWorkspaceGroupHeaderView.swift */,
 				C9A5710AC9A5710AC9A5710A /* SidebarWorkspaceGroupingMetrics.swift */,
+				D5037010000000000000002 /* RenderableSystemSymbol.swift */,
 				C9A57202C9A57202C9A57202 /* SidebarWorkspaceRenderItem.swift */,
 				C9A5720CC9A5720CC9A5720C /* TabItemView+WorkspaceGroups.swift */,
 				C9A5720AC9A5720AC9A5720A /* VerticalTabsSidebar+WorkspaceGroups.swift */,
@@ -2366,6 +2369,7 @@
 					D0C0D0C0D0C0D0C0D0C00003 /* RemoteLoopbackRuntimeBridge.swift in Sources */,
 				A5001640 /* RemoteRelayZshBootstrap.swift in Sources */,
 				E4321000E4321000E4321001 /* RemoteShellSessionParsing.swift in Sources */,
+				D5037010000000000000003 /* RenderableSystemSymbol.swift in Sources */,
 				A5001660 /* RestorableAgentSession.swift in Sources */,
 				C13519000000000000000005 /* RestorableAgentTypes.swift in Sources */,
 				B7F9A600B7F9A600B7F9A600 /* RightSidebarChromeGeometryReporting.swift in Sources */,

cmuxTests/WorkspaceGroupTests.swift

@@ -679,4 +679,33 @@ struct WorkspaceGroupTests {
         #expect(restoredGroup.customColor == "#123456")
         #expect(restoredGroup.iconSymbol == "leaf.fill")
     }
+
+    @Test func workspaceGroupIconSymbolResolutionFallsBackToRenderableIcon() {
+        #expect(RenderableSystemSymbol.resolvedWorkspaceGroupIcon(explicit: nil, configured: nil) == "folder.fill")
+        #expect(RenderableSystemSymbol.resolvedWorkspaceGroupIcon(explicit: "   ", configured: "leaf.fill") == "leaf.fill")
+        #expect(RenderableSystemSymbol.resolvedWorkspaceGroupIcon(explicit: "not.an.sf.symbol", configured: nil) == "folder.fill")
+    }
+
+    @Test func setWorkspaceGroupIconDropsInvalidSymbols() {
+        let manager = makeTabManager()
+        let groupId = manager.createWorkspaceGroup(
+            name: "G",
+            childWorkspaceIds: [manager.tabs[0].id]
+        )!
+
+        let invalidStoredIcon = manager.setWorkspaceGroupIcon(groupId: groupId, symbol: "not.an.sf.symbol")
+        #expect(invalidStoredIcon == nil)
+        #expect(manager.workspaceGroups.first { $0.id == groupId }?.iconSymbol == nil)
+
+        let validStoredIcon = manager.setWorkspaceGroupIcon(groupId: groupId, symbol: "  leaf.fill  ")
+        #expect(validStoredIcon == "leaf.fill")
+        #expect(manager.workspaceGroups.first { $0.id == groupId }?.iconSymbol == "leaf.fill")
+    }
+
+    @Test func surfaceTabIconSymbolResolutionFallsBackForInvalidInput() {
+        #expect(RenderableSystemSymbol.resolvedSurfaceTabIcon("doc.text") == "doc.text")
+        #expect(RenderableSystemSymbol.resolvedSurfaceTabIcon("   doc.text   ") == "doc.text")
+        #expect(RenderableSystemSymbol.resolvedSurfaceTabIcon("not.an.sf.symbol") == "doc.text")
+        #expect(RenderableSystemSymbol.resolvedSurfaceTabIcon("   ") == "doc.text")
+    }
 }