feat(23-03): add messageType dispatch, ChatMessageList propagation, and chatApi handoff methods

- ChatMessage: add messageType/conversationId/onHandoff props; dispatch to ChatSpecCard, ChatHandoffIndicator, ChatTaskCreatedBadge, ChatStatusUpdateBadge based on messageType
- ChatMessageList: propagate messageType and conversationId to ChatMessage; add onHandoff prop
- chatApi: add handoffSpec() and postStatusUpdate() methods

ui/src/api/chat.ts

@@ -148,4 +148,22 @@ export const chatApi = {
       credentials: "include",
     });
   },
+
+  handoffSpec(
+    conversationId: string,
+    spec: { what: string; why: string; constraints: string; success: string },
+    targetRole: string = "pm",
+  ) {
+    return api.post<{ handoffMessageId: string; issues: Array<{ id: string; identifier: string; title: string }> }>(
+      `/conversations/${conversationId}/handoff`,
+      { spec, targetRole },
+    );
+  },
+
+  postStatusUpdate(
+    conversationId: string,
+    data: { agentName: string; taskId: string; taskTitle?: string; taskUrl?: string },
+  ) {
+    return api.post<{ id: string }>(`/conversations/${conversationId}/status-update`, data);
+  },
 };

ui/src/components/ChatMessage.tsx

@@ -3,6 +3,10 @@ import { ChatMarkdownMessage } from "./ChatMarkdownMessage";
 import { ChatMessageIdentityBar } from "./ChatMessageIdentityBar";
 import { ChatStreamingCursor } from "./ChatStreamingCursor";
 import { ChatMessageActions } from "./ChatMessageActions";
+import { ChatSpecCard } from "./ChatSpecCard";
+import { ChatHandoffIndicator } from "./ChatHandoffIndicator";
+import { ChatTaskCreatedBadge } from "./ChatTaskCreatedBadge";
+import { ChatStatusUpdateBadge } from "./ChatStatusUpdateBadge";
 import { Button } from "@/components/ui/button";
 import { cn } from "../lib/utils";
 import type { AgentRole } from "@paperclipai/shared";
@@ -11,6 +15,8 @@ interface ChatMessageProps {
   id?: string;
   role: "user" | "assistant" | "system";
   content: string;
+  messageType?: string | null;
+  conversationId?: string;
   agentName?: string | null;
   agentIcon?: string | null;
   agentRole?: AgentRole | null;
@@ -19,12 +25,15 @@ interface ChatMessageProps {
   isAnyStreaming?: boolean;
   onEdit?: (messageId: string, newContent: string) => void;
   onRetry?: (messageId: string) => void;
+  onHandoff?: (spec: { what: string; why: string; constraints: string; success: string }) => void;
 }
 
 export function ChatMessage({
   id,
   role,
   content,
+  messageType,
+  conversationId,
   agentName,
   agentIcon,
   agentRole,
@@ -33,10 +42,45 @@ export function ChatMessage({
   isAnyStreaming,
   onEdit,
   onRetry,
+  onHandoff,
 }: ChatMessageProps) {
   const [isEditing, setIsEditing] = useState(false);
   const [editValue, setEditValue] = useState(content);
 
+  // Dispatch to specialized system message components (Phase 23)
+  if (role === "system" || messageType) {
+    if (messageType === "spec_card") {
+      return (
+        <ChatSpecCard
+          content={content}
+          messageId={id}
+          conversationId={conversationId}
+          onHandoff={onHandoff}
+        />
+      );
+    }
+    if (messageType === "handoff") {
+      return <ChatHandoffIndicator content={content} />;
+    }
+    if (messageType === "task_created") {
+      try {
+        const data = JSON.parse(content) as { taskId?: string; taskTitle?: string; taskUrl?: string };
+        return <ChatTaskCreatedBadge taskId={data.taskId} taskTitle={data.taskTitle} taskUrl={data.taskUrl} />;
+      } catch {
+        return <ChatTaskCreatedBadge />;
+      }
+    }
+    if (messageType === "status_update") {
+      try {
+        const data = JSON.parse(content) as { agentName: string; taskId: string; taskTitle?: string; taskUrl?: string };
+        return <ChatStatusUpdateBadge agentName={data.agentName} taskId={data.taskId} taskTitle={data.taskTitle} taskUrl={data.taskUrl} />;
+      } catch {
+        return null;
+      }
+    }
+    // Fall through to default system message rendering (plain markdown)
+  }
+
   if (role === "user") {
     if (isEditing) {
       return (

ui/src/components/ChatMessageList.tsx

@@ -16,6 +16,7 @@ interface ChatMessageListProps {
   streamingAgentRole?: AgentRole | null;
   onEdit?: (messageId: string, newContent: string) => void;
   onRetry?: (messageId: string) => void;
+  onHandoff?: (spec: { what: string; why: string; constraints: string; success: string }) => void;
   agentMap?: Map<string, { name: string; icon: string | null; role: AgentRole | null }>;
 }
 
@@ -28,6 +29,7 @@ export function ChatMessageList({
   streamingAgentRole,
   onEdit,
   onRetry,
+  onHandoff,
   agentMap,
 }: ChatMessageListProps) {
   const { messages, isLoading } = useChatMessages(conversationId);
@@ -143,6 +145,8 @@ export function ChatMessageList({
                   id={msg.id}
                   role={msg.role as "user" | "assistant" | "system"}
                   content={msg.content}
+                  messageType={msg.messageType}
+                  conversationId={conversationId}
                   agentName={agent?.name ?? streamingAgentName}
                   agentIcon={agent?.icon ?? streamingAgentIcon}
                   agentRole={agent?.role ?? streamingAgentRole}
@@ -151,6 +155,7 @@ export function ChatMessageList({
                   isAnyStreaming={isStreaming}
                   onEdit={onEdit}
                   onRetry={onRetry}
+                  onHandoff={onHandoff}
                 />
               </div>
             );