Respect split-preserve-zoom config when cycling splits

supacode/Features/Terminal/Models/WorktreeTerminalState.swift

@@ -21,6 +21,7 @@ final class WorktreeTerminalState {
 
   let tabManager: TerminalTabManager
   private let runtime: GhosttyRuntime
+  @ObservationIgnored private let splitPreserveZoomOnNavigation: () -> Bool
   private let worktree: Worktree
   @ObservationIgnored
   @SharedReader private var repositorySettings: RepositorySettings
@@ -63,8 +64,14 @@ final class WorktreeTerminalState {
   var onCommandPaletteToggle: (() -> Void)?
   var onSetupScriptConsumed: (() -> Void)?
 
-  init(runtime: GhosttyRuntime, worktree: Worktree, runSetupScript: Bool = false) {
+  init(
+    runtime: GhosttyRuntime,
+    worktree: Worktree,
+    runSetupScript: Bool = false,
+    splitPreserveZoomOnNavigation: (() -> Bool)? = nil
+  ) {
     self.runtime = runtime
+    self.splitPreserveZoomOnNavigation = splitPreserveZoomOnNavigation ?? { runtime.splitPreserveZoomOnNavigation() }
     self.worktree = worktree
     self.pendingSetupScript = runSetupScript
     self.tabManager = TerminalTabManager()
@@ -574,8 +581,13 @@ final class WorktreeTerminalState {
         return false
       }
       if tree.zoomed != nil {
-        tree = tree.settingZoomed(nil)
-        trees[tabId] = tree
+        if splitPreserveZoomOnNavigation() {
+          let nextNode = tree.root?.node(view: nextSurface)
+          tree = tree.settingZoomed(nextNode)
+        } else {
+          tree = tree.settingZoomed(nil)
+        }
+        updateTree(tree, for: tabId)
       }
       focusSurface(nextSurface, in: tabId)
       syncFocusIfNeeded()

supacode/Infrastructure/Ghostty/GhosttyRuntime.swift

@@ -557,6 +557,17 @@ final class GhosttyRuntime {
     return true
   }
 
+  func splitPreserveZoomOnNavigation() -> Bool {
+    guard let config else { return false }
+    var value: CUnsignedInt = 0
+    let key = "split-preserve-zoom"
+    guard ghostty_config_get(config, &value, key, UInt(key.count)) else { return false }
+    // Ghostty's C API bitcasts packed structs into c_uint; the first field maps to bit 0.
+    // https://github.com/ghostty-org/ghostty/blob/6057f8d/src/config/c_get.zig#L74-L84
+    // https://github.com/ghostty-org/ghostty/blob/6057f8d/src/config/c_get.zig#L226-L240
+    return value & (1 << 0) != 0
+  }
+
   func backgroundOpacity() -> Double {
     guard let config else { return 1 }
     var value: Double = 1

supacodeTests/SplitTreeTests.swift

@@ -31,6 +31,27 @@ struct SplitTreeTests {
     #expect(tree.focusTargetAfterClosing(node) === second)
   }
 
+  @Test func focusTargetNextWrapsAroundFromZoomedNode() throws {
+    let first = SplitTreeTestView()
+    let second = SplitTreeTestView()
+    let third = SplitTreeTestView()
+
+    let tree = try SplitTree(view: first)
+      .inserting(view: second, at: first, direction: .right)
+      .inserting(view: third, at: second, direction: .right)
+
+    let zoomedNode = tree.find(id: second.id)!
+    let zoomed = tree.settingZoomed(zoomedNode)
+
+    let next = zoomed.focusTarget(for: .next, from: zoomedNode)
+    #expect(next === third)
+
+    let nextNode = zoomed.find(id: third.id)!
+    let rezoomed = zoomed.settingZoomed(nextNode)
+    #expect(rezoomed.visibleLeaves().count == 1)
+    #expect(rezoomed.visibleLeaves().first === third)
+  }
+
   @Test func visibleLeavesOnlyReturnZoomedPane() throws {
     let first = SplitTreeTestView()
     let second = SplitTreeTestView()
@@ -44,6 +65,65 @@ struct SplitTreeTests {
     #expect(visibleLeaves.count == 1)
     #expect(visibleLeaves.first === second)
   }
+
+  @Test func gotoSplitPreservesZoomWhenConfigured() throws {
+    let fixture = makeWorktreeFixture(preserveZoomOnNavigation: true)
+    let first = fixture.first
+    let second = try #require(fixture.second)
+
+    #expect(fixture.state.performSplitAction(.toggleSplitZoom, for: first.id))
+    #expect(fixture.state.performSplitAction(.gotoSplit(direction: .next), for: first.id))
+
+    let visibleLeaves = fixture.state.splitTree(for: fixture.tabId).visibleLeaves()
+    #expect(visibleLeaves.count == 1)
+    #expect(visibleLeaves.first === second)
+  }
+
+  @Test func gotoSplitClearsZoomWhenNotConfigured() throws {
+    let fixture = makeWorktreeFixture(preserveZoomOnNavigation: false)
+    let first = fixture.first
+
+    #expect(fixture.state.performSplitAction(.toggleSplitZoom, for: first.id))
+    #expect(fixture.state.performSplitAction(.gotoSplit(direction: .next), for: first.id))
+
+    let visibleLeaves = fixture.state.splitTree(for: fixture.tabId).visibleLeaves()
+    #expect(visibleLeaves.count == 2)
+  }
+
+  private func makeWorktreeFixture(preserveZoomOnNavigation: Bool) -> WorktreeFixture {
+    let state = WorktreeTerminalState(
+      runtime: GhosttyRuntime(),
+      worktree: makeWorktree(),
+      splitPreserveZoomOnNavigation: { preserveZoomOnNavigation }
+    )
+    let tabId = state.createTab()!
+    let first = state.splitTree(for: tabId).root!.leftmostLeaf()
+    _ = state.performSplitAction(.newSplit(direction: .right), for: first.id)
+    let leaves = state.splitTree(for: tabId).leaves()
+    return WorktreeFixture(
+      state: state,
+      tabId: tabId,
+      first: first,
+      second: leaves.first { $0.id != first.id }
+    )
+  }
+
+  private func makeWorktree() -> Worktree {
+    Worktree(
+      id: "/tmp/repo/wt-1",
+      name: "wt-1",
+      detail: "detail",
+      workingDirectory: URL(fileURLWithPath: "/tmp/repo/wt-1"),
+      repositoryRootURL: URL(fileURLWithPath: "/tmp/repo")
+    )
+  }
+}
+
+private struct WorktreeFixture {
+  let state: WorktreeTerminalState
+  let tabId: TerminalTabID
+  let first: GhosttySurfaceView
+  let second: GhosttySurfaceView?
 }
 
 private final class SplitTreeTestView: NSView, Identifiable {