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Merged
charlesrhoward merged 1 commit into from
Feb 21, 2026
Merged

perf: reduce async waterfalls in chat sync/save path #45

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25 changes: 25 additions & 0 deletions components/ai-chat-panel.tsx
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -434,6 +434,7 @@ export function AIChatPanel({ canvasDimensions }: AIChatPanelProps) {
(((session: ChatSession, msgs: UIMessage[]) => void) & { cancel: () => void; flush: () => void }) | null
>(null)
const lastSavedMessagesRef = useRef<string>("")
const persistedMessageSignaturesRef = useRef<Map<string, string[]>>(new Map())
const cloudSaveQueueRef = useRef<Promise<void>>(Promise.resolve())
const latestCloudSaveRequestRef = useRef(0)

Expand Down Expand Up @@ -478,6 +479,20 @@ export function AIChatPanel({ canvasDimensions }: AIChatPanelProps) {
].join("|")
}, [])

const getMessageSignatures = useCallback((msgs: UIMessage[]) => {
return msgs.map((msg) => {
const dbMessage = chatService.convertToDbMessage(msg)
return [
msg.id,
dbMessage.role,
dbMessage.content ?? "",
JSON.stringify(dbMessage.parts ?? []),
JSON.stringify(dbMessage.tool_calls ?? []),
JSON.stringify(dbMessage.tool_results ?? []),
].join(":")
})
}, [])

useLoadChatHistory({
user,
currentDiagramId,
Expand All @@ -492,6 +507,7 @@ export function AIChatPanel({ canvasDimensions }: AIChatPanelProps) {
invalidatePendingCloudSaves,
getMessagesFingerprint,
lastSavedMessagesRef,
persistedMessageSignaturesRef,
localStorageKey: CHAT_HISTORY_LOCAL_KEY,
})

Expand All @@ -502,6 +518,7 @@ export function AIChatPanel({ canvasDimensions }: AIChatPanelProps) {
setIsSavingToCloud,
setCloudError,
setLastSavedToCloud,
persistedMessageSignaturesRef,
saveDebounceMs: SAVE_DEBOUNCE_MS,
})

Expand All @@ -527,6 +544,9 @@ export function AIChatPanel({ canvasDimensions }: AIChatPanelProps) {

setMessages([])
lastSavedMessagesRef.current = ""
if (chatSession) {
persistedMessageSignaturesRef.current.set(chatSession.id, [])
}

// Clear from Supabase
if (user && chatSession) {
Expand Down Expand Up @@ -558,6 +578,7 @@ export function AIChatPanel({ canvasDimensions }: AIChatPanelProps) {
const aiMessages = chatService.convertFromDbMessages(dbMessages)
setMessages(aiMessages)
lastSavedMessagesRef.current = getMessagesFingerprint(aiMessages)
persistedMessageSignaturesRef.current.set(session.id, getMessageSignatures(aiMessages))
setLastSavedToCloud(new Date())
debugLog("[chat] Loaded session:", session.id, "with", dbMessages.length, "messages")
} catch (error) {
Expand All @@ -574,6 +595,9 @@ export function AIChatPanel({ canvasDimensions }: AIChatPanelProps) {
const handleNewChat = async () => {
setMessages([])
lastSavedMessagesRef.current = ""
if (chatSession) {
persistedMessageSignaturesRef.current.set(chatSession.id, [])
}
invalidatePendingCloudSaves()
setChatSession(null)
setLastSavedToCloud(null)
Expand All @@ -596,6 +620,7 @@ export function AIChatPanel({ canvasDimensions }: AIChatPanelProps) {
})
setChatSession(newSession)
debugLog("[chat] Created new session:", newSession.id)
persistedMessageSignaturesRef.current.set(newSession.id, [])
} catch (error) {
console.error("[chat] Failed to create new session:", error)
}
Expand Down
81 changes: 73 additions & 8 deletions components/ai-chat/hooks/use-chat-sync.ts
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,31 @@ import { extractTitleFromMessages } from "@/lib/ai-chat/title-extractor"
type DebouncedCloudSave = ReturnType<typeof debounce<(session: ChatSession, msgs: UIMessage[]) => void>>

type StateSetter<T> = Dispatch<SetStateAction<T>>
type DbMessagePayload = ReturnType<typeof chatService.convertToDbMessage>

function getDbMessages(messages: UIMessage[]): DbMessagePayload[] {
return messages.map((message) => chatService.convertToDbMessage(message))
}

function getMessageSignatures(messages: UIMessage[], dbMessages: DbMessagePayload[]): string[] {
return dbMessages.map((dbMessage, index) => {
const messageId = messages[index]?.id ?? `idx-${index}`

return [
messageId,
dbMessage.role,
dbMessage.content ?? "",
JSON.stringify(dbMessage.parts ?? []),
JSON.stringify(dbMessage.tool_calls ?? []),
JSON.stringify(dbMessage.tool_results ?? []),
].join(":")
})
}

function hasMatchingPrefix(prefix: string[], target: string[]): boolean {
if (prefix.length > target.length) return false
return prefix.every((value, index) => value === target[index])
}

type LoadChatHistoryParams = {
user: User | null
Expand All @@ -24,6 +49,7 @@ type LoadChatHistoryParams = {
invalidatePendingCloudSaves: () => void
getMessagesFingerprint: (messages: UIMessage[]) => string
lastSavedMessagesRef: MutableRefObject<string>
persistedMessageSignaturesRef: MutableRefObject<Map<string, string[]>>
localStorageKey: string
}

Expand All @@ -41,6 +67,7 @@ export function useLoadChatHistory({
invalidatePendingCloudSaves,
getMessagesFingerprint,
lastSavedMessagesRef,
persistedMessageSignaturesRef,
localStorageKey,
}: LoadChatHistoryParams) {
useEffect(() => {
Expand All @@ -63,6 +90,10 @@ export function useLoadChatHistory({
const aiMessages = dbMessages.length > 0 ? chatService.convertFromDbMessages(dbMessages) : []
setMessages(aiMessages)
lastSavedMessagesRef.current = getMessagesFingerprint(aiMessages)
persistedMessageSignaturesRef.current.set(
session.id,
getMessageSignatures(aiMessages, getDbMessages(aiMessages)),
)

if (dbMessages.length > 0) {
setLastSavedToCloud(new Date())
Expand All @@ -73,12 +104,18 @@ export function useLoadChatHistory({
const extractedTitle = extractTitleFromMessages(aiMessages)

if (extractedTitle) {
const titleUpdatePromises: Promise<unknown>[] = []

if (session.title === "New Chat") {
await chatService.updateSession(session.id, { title: extractedTitle })
titleUpdatePromises.push(chatService.updateSession(session.id, { title: extractedTitle }))
}

if (currentDiagramTitle === "Untitled Diagram") {
await updateDiagramTitle(extractedTitle)
titleUpdatePromises.push(updateDiagramTitle(extractedTitle))
}

if (titleUpdatePromises.length > 0) {
await Promise.allSettled(titleUpdatePromises)
}
}
}
Expand Down Expand Up @@ -109,6 +146,9 @@ export function useLoadChatHistory({
setMessages([])
lastSavedMessagesRef.current = ""
}
if (!user) {
persistedMessageSignaturesRef.current.clear()
}
} catch (error) {
if (!isCancelled) {
console.warn("[chat] Failed to load chat history:", error)
Expand Down Expand Up @@ -139,6 +179,7 @@ export function useLoadChatHistory({
invalidatePendingCloudSaves,
getMessagesFingerprint,
lastSavedMessagesRef,
persistedMessageSignaturesRef,
localStorageKey,
])
}
Expand All @@ -150,6 +191,7 @@ type DebouncedCloudSaveParams = {
setIsSavingToCloud: StateSetter<boolean>
setCloudError: StateSetter<string | null>
setLastSavedToCloud: StateSetter<Date | null>
persistedMessageSignaturesRef: MutableRefObject<Map<string, string[]>>
saveDebounceMs: number
}

Expand All @@ -160,6 +202,7 @@ export function useDebouncedCloudSave({
setIsSavingToCloud,
setCloudError,
setLastSavedToCloud,
persistedMessageSignaturesRef,
saveDebounceMs,
}: DebouncedCloudSaveParams) {
useEffect(() => {
Expand All @@ -181,14 +224,35 @@ export function useDebouncedCloudSave({
setCloudError(null)

try {
// Once we begin replacing messages, always complete clear+save together.
// Returning early after clear can leave the session empty during rapid save invalidations.
await chatService.clearMessages(session.id)
const dbMessages = getDbMessages(msgs)
const nextSignatures = getMessageSignatures(msgs, dbMessages)
const previousSignatures = persistedMessageSignaturesRef.current.get(session.id) ?? []
let didWrite = false

// Fast path: conversation grew and prior saved messages are an unchanged prefix.
if (previousSignatures.length > 0 && hasMatchingPrefix(previousSignatures, nextSignatures)) {
if (nextSignatures.length > previousSignatures.length) {
await chatService.saveMessages(session.id, dbMessages.slice(previousSignatures.length))
didWrite = true
}
} else if (previousSignatures.length === 0) {
// New session with no known cloud messages yet.
if (dbMessages.length > 0) {
await chatService.saveMessages(session.id, dbMessages)
didWrite = true
Comment on lines +238 to +242
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@chatgpt-codex-connector chatgpt-codex-connector bot Feb 21, 2026

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P1 Badge Treat uncached signatures as unknown cloud state

The previousSignatures.length === 0 branch assumes the cloud session has no persisted messages and performs append-only writes. That assumption is false when signature cache population was skipped (for example, getMessages fails after setChatSession during history load), so later saves can append a full local transcript onto an existing cloud transcript instead of replacing it. This introduces duplicate/out-of-order history after transient load failures.

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}
} else {
// Fallback when existing messages changed in-place (edit/regeneration).
await chatService.clearMessages(session.id)
if (dbMessages.length > 0) {
await chatService.saveMessages(session.id, dbMessages)
}
didWrite = true
}

const dbMessages = msgs.map((msg) => chatService.convertToDbMessage(msg))
await chatService.saveMessages(session.id, dbMessages)
persistedMessageSignaturesRef.current.set(session.id, nextSignatures)

if (requestId === latestCloudSaveRequestRef.current) {
if (didWrite && requestId === latestCloudSaveRequestRef.current) {
setLastSavedToCloud(new Date())
}
} catch (error) {
Expand All @@ -215,6 +279,7 @@ export function useDebouncedCloudSave({
setIsSavingToCloud,
setCloudError,
setLastSavedToCloud,
persistedMessageSignaturesRef,
saveDebounceMs,
])
}
Expand Down
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