From 73cbfce432d334295532fa233ca2c55ce237e696 Mon Sep 17 00:00:00 2001
From: Lawrence Chen <54008264+lawrencecchen@users.noreply.github.com>
Date: Fri, 20 Feb 2026 20:53:59 -0800
Subject: [PATCH] Fix WKWebView JavaScript dialogs in browser panel

---
 Sources/Panels/BrowserPanel.swift             | 77 +++++++++++++++++++
 cmuxTests/CmuxWebViewKeyEquivalentTests.swift | 42 ++++++++++
 2 files changed, 119 insertions(+)

diff --git a/Sources/Panels/BrowserPanel.swift b/Sources/Panels/BrowserPanel.swift
index 873da962..12fa1c75 100644
--- a/Sources/Panels/BrowserPanel.swift
+++ b/Sources/Panels/BrowserPanel.swift
@@ -2245,6 +2245,25 @@ private class BrowserUIDelegate: NSObject, WKUIDelegate {
     var openInNewTab: ((URL) -> Void)?
     var requestNavigation: ((URL, BrowserInsecureHTTPNavigationIntent) -> Void)?
 
+    private func javaScriptDialogTitle(for webView: WKWebView) -> String {
+        if let absolute = webView.url?.absoluteString, !absolute.isEmpty {
+            return "The page at \(absolute) says:"
+        }
+        return "This page says:"
+    }
+
+    private func presentDialog(
+        _ alert: NSAlert,
+        for webView: WKWebView,
+        completion: @escaping (NSApplication.ModalResponse) -> Void
+    ) {
+        if let window = webView.window {
+            alert.beginSheetModal(for: window, completionHandler: completion)
+            return
+        }
+        completion(alert.runModal())
+    }
+
     /// Returning nil tells WebKit not to open a new window.
     /// Cmd+click opens in a new tab; regular target=_blank navigates in-place.
     func webView(
@@ -2282,4 +2301,62 @@ private class BrowserUIDelegate: NSObject, WKUIDelegate {
             completionHandler(result == .OK ? panel.urls : nil)
         }
     }
+
+    func webView(
+        _ webView: WKWebView,
+        runJavaScriptAlertPanelWithMessage message: String,
+        initiatedByFrame frame: WKFrameInfo,
+        completionHandler: @escaping () -> Void
+    ) {
+        let alert = NSAlert()
+        alert.alertStyle = .informational
+        alert.messageText = javaScriptDialogTitle(for: webView)
+        alert.informativeText = message
+        alert.addButton(withTitle: "OK")
+        presentDialog(alert, for: webView) { _ in completionHandler() }
+    }
+
+    func webView(
+        _ webView: WKWebView,
+        runJavaScriptConfirmPanelWithMessage message: String,
+        initiatedByFrame frame: WKFrameInfo,
+        completionHandler: @escaping (Bool) -> Void
+    ) {
+        let alert = NSAlert()
+        alert.alertStyle = .informational
+        alert.messageText = javaScriptDialogTitle(for: webView)
+        alert.informativeText = message
+        alert.addButton(withTitle: "OK")
+        alert.addButton(withTitle: "Cancel")
+        presentDialog(alert, for: webView) { response in
+            completionHandler(response == .alertFirstButtonReturn)
+        }
+    }
+
+    func webView(
+        _ webView: WKWebView,
+        runJavaScriptTextInputPanelWithPrompt prompt: String,
+        defaultText: String?,
+        initiatedByFrame frame: WKFrameInfo,
+        completionHandler: @escaping (String?) -> Void
+    ) {
+        let alert = NSAlert()
+        alert.alertStyle = .informational
+        alert.messageText = javaScriptDialogTitle(for: webView)
+        alert.informativeText = prompt
+        alert.addButton(withTitle: "OK")
+        alert.addButton(withTitle: "Cancel")
+
+        let field = NSTextField(frame: NSRect(x: 0, y: 0, width: 320, height: 24))
+        field.stringValue = defaultText ?? ""
+        alert.accessoryView = field
+
+        presentDialog(alert, for: webView) { response in
+            if response == .alertFirstButtonReturn {
+                completionHandler(field.stringValue)
+            } else {
+                completionHandler(nil)
+            }
+        }
+    }
 }
diff --git a/cmuxTests/CmuxWebViewKeyEquivalentTests.swift b/cmuxTests/CmuxWebViewKeyEquivalentTests.swift
index e27d3db3..548a979c 100644
--- a/cmuxTests/CmuxWebViewKeyEquivalentTests.swift
+++ b/cmuxTests/CmuxWebViewKeyEquivalentTests.swift
@@ -216,6 +216,48 @@ final class BrowserDeveloperToolsConfigurationTests: XCTestCase {
     }
 }
 
+@MainActor
+final class BrowserJavaScriptDialogDelegateTests: XCTestCase {
+    func testBrowserPanelUIDelegateImplementsJavaScriptDialogSelectors() {
+        let panel = BrowserPanel(workspaceId: UUID())
+        guard let uiDelegate = panel.webView.uiDelegate as? NSObject else {
+            XCTFail("Expected BrowserPanel webView.uiDelegate to be an NSObject")
+            return
+        }
+
+        XCTAssertTrue(
+            uiDelegate.responds(
+                to: #selector(
+                    WKUIDelegate.webView(
+                        _:runJavaScriptAlertPanelWithMessage:initiatedByFrame:completionHandler:
+                    )
+                )
+            ),
+            "Browser UI delegate must implement JavaScript alert handling"
+        )
+        XCTAssertTrue(
+            uiDelegate.responds(
+                to: #selector(
+                    WKUIDelegate.webView(
+                        _:runJavaScriptConfirmPanelWithMessage:initiatedByFrame:completionHandler:
+                    )
+                )
+            ),
+            "Browser UI delegate must implement JavaScript confirm handling"
+        )
+        XCTAssertTrue(
+            uiDelegate.responds(
+                to: #selector(
+                    WKUIDelegate.webView(
+                        _:runJavaScriptTextInputPanelWithPrompt:defaultText:initiatedByFrame:completionHandler:
+                    )
+                )
+            ),
+            "Browser UI delegate must implement JavaScript prompt handling"
+        )
+    }
+}
+
 @MainActor
 final class BrowserDeveloperToolsVisibilityPersistenceTests: XCTestCase {
     private final class FakeInspector: NSObject {