macos: handle split resizing

macos/Sources/Features/Splits/SplitTree.swift

@@ -93,6 +93,24 @@ extension SplitTree {
         
         return .init(root: newRoot, zoomed: newZoomed)
     }
+
+    /// Replace a node in the tree with a new node.
+    func replace(node: Node, with newNode: Node) throws -> Self {
+        guard let root else { throw SplitError.viewNotFound }
+        
+        // Get the path to the node we want to replace
+        guard let path = root.path(to: node) else {
+            throw SplitError.viewNotFound
+        }
+        
+        // Replace the node
+        let newRoot = try root.replaceNode(at: path, with: newNode)
+        
+        // Update zoomed if it was the replaced node
+        let newZoomed = (zoomed == node) ? newNode : zoomed
+        
+        return .init(root: newRoot, zoomed: newZoomed)
+    }
 }
 
 // MARK: SplitTree.Node
@@ -210,7 +228,7 @@ extension SplitTree.Node {
     }
 
     /// Helper function to replace a node at the given path from the root
-    private func replaceNode(at path: Path, with newNode: Self) throws -> Self {
+    func replaceNode(at path: Path, with newNode: Self) throws -> Self {
         // If path is empty, replace the root
         if path.isEmpty {
             return newNode
@@ -293,6 +311,26 @@ extension SplitTree.Node {
             ))
         }
     }
+
+    /// Resize a split node to the specified ratio.
+    /// For leaf nodes, this returns the node unchanged.
+    /// For split nodes, this creates a new split with the updated ratio.
+    func resize(to ratio: Double) -> Self {
+        switch self {
+        case .leaf:
+            // Leaf nodes don't have a ratio to resize
+            return self
+            
+        case .split(let split):
+            // Create a new split with the updated ratio
+            return .split(.init(
+                direction: split.direction,
+                ratio: ratio,
+                left: split.left,
+                right: split.right
+            ))
+        }
+    }
 }
 
 // MARK: SplitTree.Node Protocols

macos/Sources/Features/Splits/TerminalSplitTreeView.swift

@@ -2,17 +2,21 @@ import SwiftUI
 
 struct TerminalSplitTreeView: View {
     let tree: SplitTree
+    let onResize: (SplitTree.Node, Double) -> Void
 
     var body: some View {
         if let node = tree.root {
-            TerminalSplitSubtreeView(node: node, isRoot: true)
+            TerminalSplitSubtreeView(node: node, isRoot: true, onResize: onResize)
         }
     }
 }
 
 struct TerminalSplitSubtreeView: View {
+    @EnvironmentObject var ghostty: Ghostty.App
+
     let node: SplitTree.Node
     var isRoot: Bool = false
+    let onResize: (SplitTree.Node, Double) -> Void
 
     var body: some View {
         switch (node) {
@@ -23,40 +27,28 @@ struct TerminalSplitSubtreeView: View {
                 isSplit: !isRoot)
 
         case .split(let split):
-            TerminalSplitSplitView(split: split)
-        }
-    }
-}
-
-struct TerminalSplitSplitView: View {
-    @EnvironmentObject var ghostty: Ghostty.App
-
-    let split: SplitTree.Node.Split
-
-    private var splitViewDirection: SplitViewDirection {
-        switch (split.direction) {
-        case .horizontal: .horizontal
-        case .vertical: .vertical
-        }
-    }
-
-    var body: some View {
-        SplitView(
-            splitViewDirection,
-            .init(get: {
-                CGFloat(split.ratio)
-            }, set: { _ in
-                // TODO
-            }),
-            dividerColor: ghostty.config.splitDividerColor,
-            resizeIncrements: .init(width: 1, height: 1),
-            resizePublisher: .init(),
-            left: {
-                TerminalSplitSubtreeView(node: split.left)
-            },
-            right: {
-                TerminalSplitSubtreeView(node: split.right)
+            let splitViewDirection: SplitViewDirection = switch (split.direction) {
+            case .horizontal: .horizontal
+            case .vertical: .vertical
             }
-        )
+
+            SplitView(
+                splitViewDirection,
+                .init(get: {
+                    CGFloat(split.ratio)
+                }, set: {
+                    onResize(node, $0)
+                }),
+                dividerColor: ghostty.config.splitDividerColor,
+                resizeIncrements: .init(width: 1, height: 1),
+                resizePublisher: .init(),
+                left: {
+                    TerminalSplitSubtreeView(node: split.left, onResize: onResize)
+                },
+                right: {
+                    TerminalSplitSubtreeView(node: split.right, onResize: onResize)
+                }
+            )
+        }
     }
 }

macos/Sources/Features/Terminal/BaseTerminalController.swift

@@ -366,11 +366,6 @@ class BaseTerminalController: NSWindowController,
 
     // MARK: TerminalViewDelegate
 
-    // Note: this is different from surfaceDidTreeChange(from:,to:) because this is called
-    // when the currently set value changed in place and the from:to: variant is called
-    // when the variable was set.
-    func surfaceTreeDidChange() {}
-
     func focusedSurfaceDidChange(to: Ghostty.SurfaceView?) {
         let lastFocusedSurface = focusedSurface
         focusedSurface = to
@@ -420,6 +415,16 @@ class BaseTerminalController: NSWindowController,
 
     func zoomStateDidChange(to: Bool) {}
 
+    func splitDidResize(node: SplitTree.Node, to newRatio: Double) {
+        let resizedNode = node.resize(to: newRatio)
+        do {
+            surfaceTree2 = try surfaceTree2.replace(node: node, with: resizedNode)
+        } catch {
+            // TODO: log
+            return
+        }
+    }
+
     func performAction(_ action: String, on surfaceView: Ghostty.SurfaceView) {
         guard let surface = surfaceView.surface else { return }
         let len = action.utf8CString.count

macos/Sources/Features/Terminal/TerminalController.swift

@@ -107,6 +107,10 @@ class TerminalController: BaseTerminalController {
 
     override func surfaceTreeDidChange(from: Ghostty.SplitNode?, to: Ghostty.SplitNode?) {
         super.surfaceTreeDidChange(from: from, to: to)
+        
+        // Whenever our surface tree changes in any way (new split, close split, etc.)
+        // we want to invalidate our state.
+        invalidateRestorableState()
 
         // If our surface tree is now nil then we close our window.
         if (to == nil) {
@@ -696,12 +700,6 @@ class TerminalController: BaseTerminalController {
         }
     }
 
-    override func surfaceTreeDidChange() {
-        // Whenever our surface tree changes in any way (new split, close split, etc.)
-        // we want to invalidate our state.
-        invalidateRestorableState()
-    }
-
     override func zoomStateDidChange(to: Bool) {
         guard let window = window as? TerminalWindow else { return }
         window.surfaceIsZoomed = to

macos/Sources/Features/Terminal/TerminalView.swift

@@ -14,15 +14,14 @@ protocol TerminalViewDelegate: AnyObject {
     /// The cell size changed.
     func cellSizeDidChange(to: NSSize)
 
-    /// The surface tree did change in some way, i.e. a split was added, removed, etc. This is
-    /// not called initially.
-    func surfaceTreeDidChange()
-
     /// This is called when a split is zoomed.
     func zoomStateDidChange(to: Bool)
 
     /// Perform an action. At the time of writing this is only triggered by the command palette.
     func performAction(_ action: String, on: Ghostty.SurfaceView)
+
+    /// A split is resizing to a given value.
+    func splitDidResize(node: SplitTree.Node, to newRatio: Double)
 }
 
 /// The view model is a required implementation for TerminalView callers. This contains
@@ -81,7 +80,9 @@ struct TerminalView<ViewModel: TerminalViewModel>: View {
                         DebugBuildWarningView()
                     }
 
-                    TerminalSplitTreeView(tree: viewModel.surfaceTree2)
+                    TerminalSplitTreeView(
+                        tree: viewModel.surfaceTree2,
+                        onResize: { delegate?.splitDidResize(node: $0, to: $1) })
                         .environmentObject(ghostty)
                         .focused($focused)
                         .onAppear { self.focused = true }

macos/Sources/Features/Terminal/TerminalWindow.swift

@@ -30,7 +30,6 @@ class TerminalWindow: NSWindow {
         observe(\.surfaceIsZoomed, options: [.initial, .new]) { [weak self] window, _ in
             guard let tabGroup = self?.tabGroup else { return }
 
-            Ghostty.logger.warning("WOW \(window.surfaceIsZoomed)")
             self?.resetZoomTabButton.isHidden = !window.surfaceIsZoomed
             self?.updateResetZoomTitlebarButtonVisibility()
         },