## Context
Investigating a report where the AI chat showed only a `...` spinner
while the network response clearly contained `No AI models are
available`. Root cause: terminal stream failures reach the client on
**two mismatched channels**.
| Representation | Persisted (survives reload) | Rendered by client |
|---|---|---|
| AI-SDK `error` chunk (inside `stream-chunk`) | ✅ RPUSH'd to Redis | ❌
dropped by `readUIMessageStream` (no message part, no error state) |
| typed `stream-error` event | ❌ never persisted | ✅ sets the error atom
|
Live, the `stream-error` event renders. But on reload,
`chatStreamCatchupChunks` replays only the persisted **error chunk** —
which the reducer discards — and the streaming indicator never clears.
## Change
Collapse to a single typed error contract:
- **Suppress the opaque `error` chunk** in the stream job; every failure
is surfaced through the typed `stream-error` event. Errors are mapped
via `mapErrorToStreamError` so an `AiException` keeps its
`AiExceptionCode` (e.g. `API_KEY_NOT_CONFIGURED` → the existing "AI not
configured" banner) instead of leaking a raw string.
- **Persist the terminal error** next to the accumulated chunks and
expose it as an explicit `error { code message }` field on
`ChatStreamCatchupChunks`, so a client catching up after a reload
recovers it — no dependency on the AI SDK's internal chunk shape.
- **Reset per-thread stream state at job start**, so a failed turn's
leftover chunks/error never replay on the next stream.
- **Client replays the catchup error** as a terminal `stream-error`
event, which clears the streaming indicator and renders the error (fixes
the infinite spinner on a stream that ended in error).
## Notes
- `ChatStreamError` is a new metadata GraphQL type; generated types
(twenty-front metadata + client-sdk) were hand-updated to keep the tree
consistent and will be reconciled by CI's `graphql:generate` check if
anything differs.
- Server unit test added for the error mapping. No schema/DB migration.
## Test plan
- [ ] With no AI provider configured, send a chat message → error
renders immediately (not a spinner).
- [ ] Reload the thread → the error still renders (recovered from
catchup), indicator not spinning.
- [ ] Configure a provider and send again → normal streaming; no stale
error from the previous failed turn.
<!-- This is an auto-generated description by cubic. -->
<a
href="https://cubic.dev/pr/twentyhq/twenty/pull/22434?utm_source=github"
target="_blank" rel="noopener noreferrer"
data-no-image-dialog="true"><picture><source
media="(prefers-color-scheme: dark)"
srcset="https://www.cubic.dev/buttons/review-in-cubic-dark.svg"><source
media="(prefers-color-scheme: light)"
srcset="https://www.cubic.dev/buttons/review-in-cubic-light.svg"><img
alt="Review in cubic"
src="https://www.cubic.dev/buttons/review-in-cubic-dark.svg"></picture></a>
<!-- End of auto-generated description by cubic. -->
Félix Malfait
d709467902
