fix(macos): prevent crash when Textual syntax highlighting bundle is missing

Add graceful fallback to SwiftUI's native AttributedString markdown rendering
when the Textual resource bundle is not found. This prevents the app from
crashing with an NSBundle.module assertion failure when code blocks are
rendered without the prism-bundle.js resource being properly embedded.

Fixes #2002

apps/shared/OpenClawKit/Sources/OpenClawChatUI/ChatMarkdownRenderer.swift

@@ -6,6 +6,23 @@ public enum ChatMarkdownVariant: String, CaseIterable, Sendable {
     case compact
 }
 
+// MARK: - Textual Bundle Availability
+
+/// Checks if the Textual syntax highlighting bundle is available.
+/// This must be called BEFORE any Textual types are accessed to avoid a crash
+/// from SPM's generated Bundle.module accessor when the bundle is missing.
+private let textualBundleAvailable: Bool = {
+    let bundleNames = ["textual_Textual", "Textual_Textual"]
+    guard let resourceURL = Bundle.main.resourceURL else { return false }
+    for name in bundleNames {
+        let bundleURL = resourceURL.appendingPathComponent("\(name).bundle")
+        if FileManager.default.fileExists(atPath: bundleURL.path) {
+            return true
+        }
+    }
+    return false
+}()
+
 @MainActor
 struct ChatMarkdownRenderer: View {
     enum Context {
@@ -22,12 +39,20 @@ struct ChatMarkdownRenderer: View {
     var body: some View {
         let processed = ChatMarkdownPreprocessor.preprocess(markdown: self.text)
         VStack(alignment: .leading, spacing: 10) {
-            StructuredText(markdown: processed.cleaned)
-                .modifier(ChatMarkdownStyle(
-                    variant: self.variant,
-                    context: self.context,
+            if textualBundleAvailable {
+                StructuredText(markdown: processed.cleaned)
+                    .modifier(ChatMarkdownStyle(
+                        variant: self.variant,
+                        context: self.context,
+                        font: self.font,
+                        textColor: self.textColor))
+            } else {
+                // Fallback when Textual's resource bundle is missing (avoids crash).
+                FallbackMarkdownText(
+                    text: processed.cleaned,
                     font: self.font,
-                    textColor: self.textColor))
+                    textColor: self.textColor)
+            }
 
             if !processed.images.isEmpty {
                 InlineImageList(images: processed.images)
@@ -88,3 +113,33 @@ private struct InlineImageList: View {
         }
     }
 }
+
+// MARK: - Fallback Markdown Rendering
+
+/// Fallback markdown renderer using SwiftUI's native AttributedString.
+/// Used when Textual's resource bundle is missing to avoid crashes.
+@MainActor
+private struct FallbackMarkdownText: View {
+    let text: String
+    let font: Font
+    let textColor: Color
+
+    var body: some View {
+        if let attributed = try? AttributedString(markdown: self.text, options: Self.markdownOptions) {
+            Text(attributed)
+                .font(self.font)
+                .foregroundStyle(self.textColor)
+                .textSelection(.enabled)
+        } else {
+            Text(self.text)
+                .font(self.font)
+                .foregroundStyle(self.textColor)
+                .textSelection(.enabled)
+        }
+    }
+
+    private static let markdownOptions = AttributedString.MarkdownParsingOptions(
+        allowsExtendedAttributes: true,
+        interpretedSyntax: .inlineOnlyPreservingWhitespace,
+        failurePolicy: .returnPartiallyParsedIfPossible)
+}