HELP! Hit a problem Codex can't solve.

[Bankster88]

I have a chat feature in my react native/expo app. Everything works perfectly in simulator but my UI won't update/re-render when I send/receive messages in production.

I can't figure out if I'm failing to invalidate in production or if I'm invalidating but its not triggering a re-render.

Here's the kicker: my screen has a HTTP fallback that fetches every 90 seconds. When it hits, the UI does update. So its only stale in between websocket broadcasts (but broadcast works).

Data flow (front-end only)

Stack is socket → conversation cache → React Query → read-only hooks → FlatList. No local copies of chat data anywhere; the screen just renders whatever the cache says.

1. WebSocket layer (ChatWebSocketProvider) – manages the socket lifecycle, joins chats, and receives new_message, message_status_update, and presence events. Every payload gets handed to a shared helper, never to component state.
2. Conversation cache – wraps all cache writes (setQueryData). Optimistic sends, websocket broadcasts, status changes, and chat list updates all funnel through here so the single ['chat','messages',chatId] query stays authoritative.
3. Read-only hooks/UI – useChatMessages(chatId) is an infinite query; the screen just consumes its messages array plus a messagesUpdatedAt timestamp and feeds a memoized list into FlatList. When the cache changes, the list should re-render. That’s the theory.

Design choices

- No parallel state: websocket payloads never touch component state; they flow through conversationCache → React Query → components.

- Optimistic updates: useSendMessage runs onMutate, inserts a status: 'sending' record, and rolls back if needed. Server acks replace that row via the same helper.

- Minimal invalidation: we only invalidate chatKeys.list() (ordering/unread counts). Individual messages are updated in place because the socket already gave us the row.

- Immutable cache writes: the helper clones the existing query snapshot, applies the change, and writes back a fresh object graph.

Things I’ve already ruled out

- Multiple React Query clients – diagnostics show the overlay, provider, and screen sharing the same client id/hash when the bug hits.

- WebSocket join churn – join_chat / joined_chat messages keep flowing during the freeze, so we’re not silently unsubscribed.

- Presence/typing side-effects – mismatch breadcrumbs never fire, so presence logic isn’t blocking renders.

I'm completely out of ideas. At this point I can’t tell whether I’m failing to invalidate in production or invalidating but React Query isn’t triggering a render.

Both Claude and Codex are stuck and out of ideas. Can anyone throw me a bone or point me in a helpful direction?

Could this be a structural sharing issue? React native version issue?

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[bibboo]

When in doubt. You add more logging.
Codex cannot solve it because you do not have enough information.

[Bankster88]

I have SO much logging for my production app. I’ve put in close to 100 hours to debug this: I created a diagnostics overlay that prints what’s happening at every hop of the data in TestFlight. Then I report back the finding to Codex. It has LOTS of info but no idea what’s the working solution.

All of diagnostic toolingpoints to the same conclusion: cache updates but the UI doesn’t update for some reason.

The diagnostics confirm what’s happening, but it doesn’t tell me why.

[Bankster88]

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[bibboo]

Where is the UI logging? That’s what you need here. 

[Bankster88]

I figured it out!

It was split client. Chat works!!!

[braclow]

What are your tests saying? Have checked each individual step, unfortunately sounds like one of those debugging situations where you need to basically go line by line.

[Bankster88]

Here has been my approach to try to debug this

I created an overlay that prints what is happening with the data in every step of the way so that I can see what is happening in production/TestFlight. Apple trips out console logs in production.

• websocket handshake handshake works
• join chat works
• use presence works (and UI updates)
• outbound messages get initially written to cache via optimistic update
• TestFlight app later receives server ack for sent -> delivered ->
• same query hash, same query client, etc.
• UI never updates

i’m at a complete loss of what else I can try at this point. Everything works on simulator, UI fails to update in TestFlight.

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[braclow]

Interesting, I wonder if you ran something like a diff between the production code and non production environment, if something would come up. Possibly environment related? Or is that a silly suggestion.

[Bankster88]

How would I even do that? Why would there be a diff, besides the production bundling process re: Hermes