Path-A task 3/5. Replaces the setTimeout mock that returned the literal
"Full AI integration is coming soon!" string with a real streaming
provider call.
* apps/web/app/api/chat/route.ts (new): POST handler that runs the
same auth + resolveWorkspace pipeline workspaceProcedure uses, then
streams a response from streamText().toDataStreamResponse(). Maps
resolveWorkspace's TRPCError codes to HTTP status (401/403/404/400).
Returns a structured 503 with a human-readable hint when
OPENAI_API_KEY is unset, so the misconfiguration is surfaced rather
than masked by a fake stream.
* apps/web/app/(app)/[workspaceSlug]/ai/page.tsx: replace the local
message-state + setTimeout placeholder with useChat from
@ai-sdk/react. workspace slug is sent on every request body so the
server can enforce tenant scoping. Adds a ChatErrorBanner that
parses the JSON error body the route emits and renders amber for
the "unavailable" case, destructive for other failures.
* apps/web/package.json: pull in @ai-sdk/react as a direct dep
(previously only transitive via `ai`).
The existing aiRouter.chat tRPC mutation is left intact — it powers
the right-panel command palette via the non-streaming generateText
path, and rebuilding that as streaming was outside the scope of
making the dedicated chat page usable.
Provider selection still flows from env per packages/ai conventions:
OPENAI_API_KEY gates availability, OPENAI_BASE_URL lets operators
route through Ollama on CT 108 transparently, OPENAI_MODEL overrides
the default gpt-4o-mini.
`pnpm lint && pnpm type-check` clean. Closes
plans/Plan-daily-driver-finish/Epic-shipping-the-shell/
Task-wire-ai-chat-to-trpc.md.
Co-authored-by: Cursor <cursoragent@cursor.com>