diff --git a/Sources/AppDelegate.swift b/Sources/AppDelegate.swift
index 9df55688..0eb83629 100644
--- a/Sources/AppDelegate.swift
+++ b/Sources/AppDelegate.swift
@@ -5725,10 +5725,60 @@ final class AppDelegate: NSObject, NSApplicationDelegate, UNUserNotificationCent
                     "expectedLatestWindowId": window1.windowId.uuidString,
                     "expectedLatestTabId": tabId1.uuidString,
                 ], at: path)
+                self.publishMultiWindowNotificationSocketStateIfNeeded(at: path)
             }
         }
     }
 
+    private func publishMultiWindowNotificationSocketStateIfNeeded(at path: String) {
+        let env = ProcessInfo.processInfo.environment
+        guard env["CMUX_UI_TEST_SOCKET_SANITY"] == "1" else { return }
+
+        guard let config = socketListenerConfigurationIfEnabled() else {
+            writeMultiWindowNotificationTestData([
+                "socketExpectedPath": env["CMUX_SOCKET_PATH"] ?? "",
+                "socketMode": "off",
+                "socketReady": "0",
+                "socketIsRunning": "0",
+                "socketAcceptLoopAlive": "0",
+                "socketPathMatches": "0",
+                "socketPathExists": "0",
+                "socketFailureSignals": "socket_disabled",
+            ], at: path)
+            return
+        }
+
+        writeMultiWindowNotificationTestData([
+            "socketExpectedPath": config.path,
+            "socketMode": config.mode.rawValue,
+            "socketReady": "pending",
+        ], at: path)
+
+        restartSocketListenerIfEnabled(source: "uiTest.multiWindowNotifications.setup")
+
+        let deadline = Date().addingTimeInterval(12.0)
+        func publish() {
+            let health = TerminalController.shared.socketListenerHealth(expectedSocketPath: config.path)
+            let isTimedOut = Date() >= deadline
+            writeMultiWindowNotificationTestData([
+                "socketExpectedPath": config.path,
+                "socketMode": config.mode.rawValue,
+                "socketReady": health.isHealthy ? "1" : (isTimedOut ? "0" : "pending"),
+                "socketIsRunning": health.isRunning ? "1" : "0",
+                "socketAcceptLoopAlive": health.acceptLoopAlive ? "1" : "0",
+                "socketPathMatches": health.socketPathMatches ? "1" : "0",
+                "socketPathExists": health.socketPathExists ? "1" : "0",
+                "socketFailureSignals": health.failureSignals.joined(separator: ","),
+            ], at: path)
+            guard !health.isHealthy, !isTimedOut else { return }
+            DispatchQueue.main.asyncAfter(deadline: .now() + 0.05) {
+                publish()
+            }
+        }
+
+        publish()
+    }
+
     private func writeMultiWindowNotificationTestData(_ updates: [String: String], at path: String) {
         var payload = loadMultiWindowNotificationTestData(at: path)
         for (key, value) in updates {
diff --git a/cmuxUITests/MultiWindowNotificationsUITests.swift b/cmuxUITests/MultiWindowNotificationsUITests.swift
index 4f875312..e5c4e4c7 100644
--- a/cmuxUITests/MultiWindowNotificationsUITests.swift
+++ b/cmuxUITests/MultiWindowNotificationsUITests.swift
@@ -207,19 +207,44 @@ final class MultiWindowNotificationsUITests: XCTestCase {
             "Expected app to launch for notify focus regression test. state=\(app.state.rawValue)"
         )
         XCTAssertTrue(
-            waitForData(keys: ["tabId2"], timeout: 15.0),
-            "Expected multi-window notification setup data"
+            waitForDataMatch(timeout: 20.0) { data in
+                let tabId2 = data["tabId2"] ?? ""
+                let socketReady = data["socketReady"] ?? ""
+                return !tabId2.isEmpty && !socketReady.isEmpty && socketReady != "pending"
+            },
+            "Expected multi-window notification setup data and socket readiness"
         )
 
-        guard let tabId2 = loadData()?["tabId2"], !tabId2.isEmpty else {
+        guard let setup = loadData() else {
+            XCTFail("Missing setup data")
+            return
+        }
+        guard let tabId2 = setup["tabId2"], !tabId2.isEmpty else {
             XCTFail("Missing setup workspace id")
             return
         }
+        if let expectedSocketPath = setup["socketExpectedPath"], !expectedSocketPath.isEmpty {
+            socketPath = expectedSocketPath
+        }
+        if setup["socketReady"] != "1" {
+            XCTFail(
+                "Control socket unavailable in this test environment. expected=\(socketPath) " +
+                "mode=\(setup["socketMode"] ?? "") running=\(setup["socketIsRunning"] ?? "") " +
+                "acceptLoopAlive=\(setup["socketAcceptLoopAlive"] ?? "") pathMatches=\(setup["socketPathMatches"] ?? "") " +
+                "pathExists=\(setup["socketPathExists"] ?? "") signals=\(setup["socketFailureSignals"] ?? "")"
+            )
+            return
+        }
 
         XCTAssertTrue(waitForWindowCount(atLeast: 2, app: app, timeout: 6.0))
 
-        guard let resolvedPath = resolveSocketPath(timeout: 20.0, requiredWorkspaceId: tabId2) else {
-            XCTFail("Control socket unavailable in this test environment. requested=\(socketPath)")
+        guard let resolvedPath = resolveSocketPath(timeout: 5.0, requiredWorkspaceId: tabId2) else {
+            XCTFail(
+                "Control socket unavailable in this test environment. requested=\(socketPath) " +
+                "mode=\(setup["socketMode"] ?? "") running=\(setup["socketIsRunning"] ?? "") " +
+                "acceptLoopAlive=\(setup["socketAcceptLoopAlive"] ?? "") pathMatches=\(setup["socketPathMatches"] ?? "") " +
+                "pathExists=\(setup["socketPathExists"] ?? "") signals=\(setup["socketFailureSignals"] ?? "")"
+            )
             return
         }
         socketPath = resolvedPath
@@ -342,6 +367,20 @@ final class MultiWindowNotificationsUITests: XCTestCase {
         return false
     }
 
+    private func waitForDataMatch(timeout: TimeInterval, predicate: ([String: String]) -> Bool) -> Bool {
+        let deadline = Date().addingTimeInterval(timeout)
+        while Date() < deadline {
+            if let data = loadData(), predicate(data) {
+                return true
+            }
+            RunLoop.current.run(until: Date().addingTimeInterval(0.05))
+        }
+        if let data = loadData(), predicate(data) {
+            return true
+        }
+        return false
+    }
+
     private func waitForSocketPong(timeout: TimeInterval) -> String? {
         let deadline = Date().addingTimeInterval(timeout)
         var lastResponse: String?