fix: handle edge cases in chat panel and message display

- Handle undefined edit.search/edit.replace in EditDiffDisplay
- Handle empty chartXML when displaying diagrams
- Add missing access code header to regenerate and edit message handlers

components/chat-panel.tsx

@@ -347,6 +347,7 @@ Please retry with an adjusted search pattern or use display_diagram if retries a
         })
 
         // Now send the message after state is guaranteed to be updated
+        const accessCode = localStorage.getItem(STORAGE_ACCESS_CODE_KEY) || ""
         sendMessage(
             { parts: userParts },
             {
@@ -354,6 +355,9 @@ Please retry with an adjusted search pattern or use display_diagram if retries a
                     xml: savedXml,
                     sessionId,
                 },
+                headers: {
+                    "x-access-code": accessCode,
+                },
             },
         )
     }
@@ -404,6 +408,7 @@ Please retry with an adjusted search pattern or use display_diagram if retries a
         })
 
         // Now send the edited message after state is guaranteed to be updated
+        const accessCode = localStorage.getItem(STORAGE_ACCESS_CODE_KEY) || ""
         sendMessage(
             { parts: newParts },
             {
@@ -411,6 +416,9 @@ Please retry with an adjusted search pattern or use display_diagram if retries a
                     xml: savedXml,
                     sessionId,
                 },
+                headers: {
+                    "x-access-code": accessCode,
+                },
             },
         )
     }