feat: add Save to space button in Nova chat

apps/web/components/chat/index.tsx

@@ -143,6 +143,11 @@ export function ChatSidebar({
 	const [confirmingDeleteId, setConfirmingDeleteId] = useState<string | null>(
 		null,
 	)
+	const [saveState, setSaveState] = useState<"idle" | "saving" | "saved">(
+		"idle",
+	)
+	const saveStateRef = useRef<"idle" | "saving" | "saved">("idle")
+	saveStateRef.current = saveState
 	const messagesContainerRef = useRef<HTMLDivElement>(null)
 	const isScrolledToBottomRef = useRef(true)
 	const userJustSentRef = useRef(false)
@@ -426,8 +431,48 @@ export function ChatSidebar({
 		setThreadId(null)
 		setFallbackChatId(newChatId)
 		setInput("")
+		setSaveState("idle")
 	}, [setThreadId, setMessages])
 
+	// Reset saveState to idle when a new assistant message arrives
+	useEffect(() => {
+		if (messages.at(-1)?.role === "assistant") {
+			setSaveState("idle")
+		}
+	}, [messages])
+
+	// Reset saveState when the active space changes so saved state doesn't carry over
+	// biome-ignore lint/correctness/useExhaustiveDependencies: chatProject triggers the reset but isn't used inside the effect body
+	useEffect(() => {
+		setSaveState("idle")
+	}, [chatProject])
+
+	const handleSaveToSpace = useCallback(async () => {
+		if (saveStateRef.current !== "idle" || messages.length === 0) return
+		setSaveState("saving")
+		try {
+			const response = await fetch(`${chatApiBase}/chat/save-as-document`, {
+				method: "POST",
+				credentials: "include",
+				headers: { "Content-Type": "application/json" },
+				body: JSON.stringify({
+					chatId: currentChatId,
+					projectId: chatProject,
+					messages,
+				}),
+			})
+			if (!response.ok) throw new Error("Save failed")
+			setSaveState("saved")
+			analytics.chatSavedToSpace({
+				chat_id: currentChatId,
+				project_id: chatProject,
+			})
+		} catch (error) {
+			console.error("Failed to save chat:", error)
+			setSaveState("idle")
+		}
+	}, [chatApiBase, messages, currentChatId, chatProject])
+
 	const fetchThreads = useCallback(async () => {
 		setIsLoadingThreads(true)
 		try {
@@ -905,6 +950,20 @@ export function ChatSidebar({
 
 	const chatToolbarActions = (
 		<div className="flex shrink-0 items-center gap-2">
+			{messages.length > 0 && !isAutoChatSpace && (
+				<button
+					type="button"
+					disabled={saveState === "saving" || isResponding}
+					onClick={handleSaveToSpace}
+					className="text-xs text-muted-foreground hover:text-foreground transition-colors disabled:opacity-50"
+				>
+					{saveState === "saving"
+						? "Saving..."
+						: saveState === "saved"
+							? "Saved to space"
+							: `Save to ${chatSpaceLabel}`}
+				</button>
+			)}
 			<button
 				type="button"
 				onClick={() => setIsHistoryOpen(true)}

apps/web/lib/analytics.ts

@@ -146,6 +146,9 @@ export const analytics = {
 	chatThreadDeleted: (props: { thread_id: string }) =>
 		safeCapture("chat_thread_deleted", props),
 
+	chatSavedToSpace: (props: { chat_id: string; project_id: string }) =>
+		safeCapture("chat_saved_to_space", props),
+
 	modelChanged: (props: { model: string }) =>
 		safeCapture("model_changed", props),