diff --git a/Sources/AppDelegate.swift b/Sources/AppDelegate.swift
index 0aa385ef..e17b0209 100644
--- a/Sources/AppDelegate.swift
+++ b/Sources/AppDelegate.swift
@@ -2390,6 +2390,11 @@ final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCent
                 }
                 self.moveUITestWindowToTargetDisplayIfNeeded()
                 NSRunningApplication.current.activate(options: [.activateAllWindows, .activateIgnoringOtherApps])
+                // On headless CI runners, activate() silently fails (no GUI session).
+                // Force windows visible so the terminal surface starts rendering.
+                for window in NSApp.windows {
+                    window.orderFrontRegardless()
+                }
                 self.writeUITestDiagnosticsIfNeeded(stage: "afterForceWindow")
             }
             if env["CMUX_UI_TEST_BROWSER_IMPORT_HINT_OPEN_BLANK_BROWSER"] == "1" {