diff --git a/cmuxTests/WorkspaceSplitStartupCommandTests.swift b/cmuxTests/WorkspaceSplitStartupCommandTests.swift
index dbe7e8191fa0..1425cee669d9 100644
--- a/cmuxTests/WorkspaceSplitStartupCommandTests.swift
+++ b/cmuxTests/WorkspaceSplitStartupCommandTests.swift
@@ -153,7 +153,7 @@ final class WorkspaceSplitStartupCommandTests: XCTestCase {
         )
     }
 
-    func testTabManagerSplitCarriesRequestedWorkingDirectoryAndStartupCommand() {
+    func testTabManagerSplitCarriesRequestedWorkingDirectoryAndStartupCommand() throws {
         let manager = TabManager()
         guard let workspace = manager.selectedWorkspace,
               let sourcePanelId = workspace.focusedPanelId else {
@@ -162,6 +162,8 @@ final class WorkspaceSplitStartupCommandTests: XCTestCase {
         }
 
         let requestedDirectory = "/tmp/cmux-split-startup-\(UUID().uuidString)"
+        try FileManager.default.createDirectory(atPath: requestedDirectory, withIntermediateDirectories: true)
+        defer { try? FileManager.default.removeItem(atPath: requestedDirectory) }
         let startupCommand = "/tmp/cmux-tmux-command-\(UUID().uuidString).sh"
         let tmuxStartCommand = "node /opt/oh-my-codex/dist/omx.js hud --watch"
         let initialDividerPosition = 0.875
@@ -239,6 +241,8 @@ final class WorkspaceSplitStartupCommandTests: XCTestCase {
         let placeholderCommand = "/bin/sh -c 'printf placeholder; while :; do sleep 86400; done'"
         let attachCommand = "/bin/sh -c 'opencode attach http://127.0.0.1:4096 --session subagent --dir /tmp/omo'"
         let requestedDirectory = "/tmp/cmux-respawn-\(UUID().uuidString)"
+        try FileManager.default.createDirectory(atPath: requestedDirectory, withIntermediateDirectories: true)
+        defer { try? FileManager.default.removeItem(atPath: requestedDirectory) }
         let startupEnvironment = [
             "CMUX_OMO_SUBAGENT": "1",
             "OMO_SUBAGENT_DESC": "test"
diff --git a/cmuxTests/WorkspaceTerminalTabWorkingDirectoryTests.swift b/cmuxTests/WorkspaceTerminalTabWorkingDirectoryTests.swift
index 9094a51e6ed3..885c56e83c54 100644
--- a/cmuxTests/WorkspaceTerminalTabWorkingDirectoryTests.swift
+++ b/cmuxTests/WorkspaceTerminalTabWorkingDirectoryTests.swift
@@ -15,6 +15,8 @@ struct WorkspaceTerminalTabWorkingDirectoryTests {
     @Test("Cmd+T after session restore uses workspace cwd when focused agent has no terminal cwd")
     func cmdTAfterSessionRestoreUsesWorkspaceCurrentDirectoryForAgentPane() throws {
         let workspaceDirectory = "/tmp/cmux-cmdt-restore-\(UUID().uuidString)"
+        try FileManager.default.createDirectory(atPath: workspaceDirectory, withIntermediateDirectories: true)
+        defer { try? FileManager.default.removeItem(atPath: workspaceDirectory) }
         let agentPanelId = UUID()
         let snapshot = SessionWorkspaceSnapshot(
             workspaceId: UUID(),
@@ -396,6 +398,8 @@ struct WorkspaceTerminalTabWorkingDirectoryTests {
     func newTerminalToRightUsesAnchorTabWorkingDirectoryWhenAnchorIsNotSelected() throws {
         let selectedDirectory = "/tmp/cmux-selected-\(UUID().uuidString)"
         let anchorDirectory = "/tmp/cmux-anchor-\(UUID().uuidString)"
+        try FileManager.default.createDirectory(atPath: anchorDirectory, withIntermediateDirectories: true)
+        defer { try? FileManager.default.removeItem(atPath: anchorDirectory) }
         let workspace = Workspace(workingDirectory: "/tmp/cmux-workspace-\(UUID().uuidString)")
         let paneId = try #require(workspace.bonsplitController.focusedPaneId)
         let selectedPanel = try #require(workspace.focusedTerminalPanel)
@@ -433,6 +437,8 @@ struct WorkspaceTerminalTabWorkingDirectoryTests {
     func surfaceCreateInheritsWorkspaceCurrentDirectoryForAgentPane() throws {
         let previousManager = TerminalController.shared.activeTabManagerForCallerNotification()
         let workspaceDirectory = "/tmp/cmux-surface-create-\(UUID().uuidString)"
+        try FileManager.default.createDirectory(atPath: workspaceDirectory, withIntermediateDirectories: true)
+        defer { try? FileManager.default.removeItem(atPath: workspaceDirectory) }
         let manager = TabManager()
         let workspace = try #require(manager.selectedWorkspace)
         workspace.currentDirectory = workspaceDirectory
diff --git a/cmuxTests/WorkspaceTerminalWorkingDirectoryFallbackTests.swift b/cmuxTests/WorkspaceTerminalWorkingDirectoryFallbackTests.swift
index 85e5c4c1cd3c..0e1db839646e 100644
--- a/cmuxTests/WorkspaceTerminalWorkingDirectoryFallbackTests.swift
+++ b/cmuxTests/WorkspaceTerminalWorkingDirectoryFallbackTests.swift
@@ -74,6 +74,8 @@ import Testing
 
         let staleCurrentDirectory = workspace.currentDirectory
         let requestedDirectory = "/tmp/cmux-requested-tab-cwd-\(UUID().uuidString)"
+        try FileManager.default.createDirectory(atPath: requestedDirectory, withIntermediateDirectories: true)
+        defer { try? FileManager.default.removeItem(atPath: requestedDirectory) }
         let sourcePanel = try #require(
             workspace.newTerminalSurface(
                 inPane: sourcePaneId,
diff --git a/cmuxTests/WorkspaceUnitTests.swift b/cmuxTests/WorkspaceUnitTests.swift
index 31c30dc70ac8..1762588dc338 100644
--- a/cmuxTests/WorkspaceUnitTests.swift
+++ b/cmuxTests/WorkspaceUnitTests.swift
@@ -7494,12 +7494,20 @@ final class WorkspacePanelGitBranchTests: XCTestCase {
         XCTAssertEqual(branches.map(\.isDirty), [true, false, false])
     }
 
-    func testSidebarBranchDirectoryEntriesStayStableAcrossFocusedSplitChanges() {
+    func testSidebarBranchDirectoryEntriesStayStableAcrossFocusedSplitChanges() throws {
         let workspace = Workspace()
-        let leftLiveDirectory = "/repo/left/live"
-        let rightFocusedDirectory = "/repo/right/focused"
-        let leftFocusedDirectory = "/repo/left/focused"
-        let rightRequestedDirectory = "/repo/right/requested"
+        // New splits resolve local cwds against the filesystem (#16248), so
+        // the inherited directories must exist.
+        let root = FileManager.default.temporaryDirectory
+            .appendingPathComponent("cmux-sidebar-dirs-\(UUID().uuidString)", isDirectory: true)
+        defer { try? FileManager.default.removeItem(at: root) }
+        let leftLiveDirectory = root.appendingPathComponent("left/live", isDirectory: true).path
+        let rightFocusedDirectory = root.appendingPathComponent("right/focused", isDirectory: true).path
+        let leftFocusedDirectory = root.appendingPathComponent("left/focused", isDirectory: true).path
+        let rightRequestedDirectory = root.appendingPathComponent("right/requested", isDirectory: true).path
+        for directory in [leftLiveDirectory, rightFocusedDirectory, leftFocusedDirectory, rightRequestedDirectory] {
+            try FileManager.default.createDirectory(atPath: directory, withIntermediateDirectories: true)
+        }
 
         guard let leftPanelId = workspace.focusedPanelId else {
             XCTFail("Expected initial focused panel")