Show diffs in todo list updates

Author: mrubens

webview-ui/src/components/chat/ChatRow.tsx

@@ -107,7 +107,7 @@ export const ChatRowContent = ({
 	editable,
 }: ChatRowContentProps) => {
 	const { t } = useTranslation()
-	const { mcpServers, alwaysAllowMcp, currentCheckpoint } = useExtensionState()
+	const { mcpServers, alwaysAllowMcp, currentCheckpoint, clineMessages } = useExtensionState()
 	const [reasoningCollapsed, setReasoningCollapsed] = useState(true)
 	const [isDiffErrorExpanded, setIsDiffErrorExpanded] = useState(false)
 	const [showCopySuccess, setShowCopySuccess] = useState(false)
@@ -436,9 +436,31 @@ export const ChatRowContent = ({
 			}
 			case "updateTodoList" as any: {
 				const todos = (tool as any).todos || []
+
+				// Try to find previous todo list from earlier messages
+				const currentMessageIndex = clineMessages.findIndex((msg) => msg.ts === message.ts)
+				let previousTodos: any[] = []
+
+				// Look backwards through messages to find the most recent updateTodoList
+				for (let i = currentMessageIndex - 1; i >= 0; i--) {
+					const prevMessage = clineMessages[i]
+					if (prevMessage.ask === "tool" && prevMessage.text) {
+						try {
+							const prevTool = JSON.parse(prevMessage.text)
+							if (prevTool.tool === "updateTodoList" && prevTool.todos) {
+								previousTodos = prevTool.todos
+								break
+							}
+						} catch {
+							// Ignore parsing errors
+						}
+					}
+				}
+
 				return (
 					<UpdateTodoListToolBlock
 						todos={todos}
+						previousTodos={previousTodos}
 						content={(tool as any).content}
 						onChange={(updatedTodos) => {
 							if (typeof vscode !== "undefined" && vscode?.postMessage) {