story-kit: accept 145_story_persist_chat_history_to_localstorage_across_rebuilds

frontend/src/hooks/useChatHistory.ts

@@ -0,0 +1,67 @@
+import { useCallback, useEffect, useRef, useState } from "react";
+import type { Message } from "../types";
+
+const STORAGE_KEY_PREFIX = "storykit-chat-history:";
+
+function storageKey(projectPath: string): string {
+	return `${STORAGE_KEY_PREFIX}${projectPath}`;
+}
+
+function loadMessages(projectPath: string): Message[] {
+	try {
+		const raw = localStorage.getItem(storageKey(projectPath));
+		if (!raw) return [];
+		const parsed: unknown = JSON.parse(raw);
+		if (!Array.isArray(parsed)) return [];
+		return parsed as Message[];
+	} catch {
+		return [];
+	}
+}
+
+function saveMessages(projectPath: string, messages: Message[]): void {
+	try {
+		if (messages.length === 0) {
+			localStorage.removeItem(storageKey(projectPath));
+		} else {
+			localStorage.setItem(storageKey(projectPath), JSON.stringify(messages));
+		}
+	} catch (e) {
+		console.warn("Failed to persist chat history to localStorage:", e);
+	}
+}
+
+export function useChatHistory(projectPath: string) {
+	const [messages, setMessagesState] = useState<Message[]>(() =>
+		loadMessages(projectPath),
+	);
+	const projectPathRef = useRef(projectPath);
+
+	// Keep the ref in sync so the effect closure always has the latest path.
+	projectPathRef.current = projectPath;
+
+	// Persist whenever messages change.
+	useEffect(() => {
+		saveMessages(projectPathRef.current, messages);
+	}, [messages]);
+
+	const setMessages = useCallback(
+		(update: Message[] | ((prev: Message[]) => Message[])) => {
+			setMessagesState(update);
+		},
+		[],
+	);
+
+	const clearMessages = useCallback(() => {
+		setMessagesState([]);
+		// Eagerly remove from storage so clearSession doesn't depend on the
+		// effect firing before the component unmounts or re-renders.
+		try {
+			localStorage.removeItem(storageKey(projectPathRef.current));
+		} catch {
+			// Ignore — quota or security errors.
+		}
+	}, []);
+
+	return { messages, setMessages, clearMessages } as const;
+}