Generate the /dashboard/api/* proxy destination at build time from
LANGGRAPH_BACKEND_URL via the Vercel Build Output API, instead of hardcoding
it in ui/vercel.json. This lets the dev and main branches stay byte-identical
(required by the fast-forward-only prod promotion) while each Vercel project
proxies to its own LangGraph backend purely via its own env var — so both the
dev and prod dashboards can be git-linked.
- ui/vercel.json: drop the hardcoded rewrites; buildCommand -> bun run vercel-build
- ui/package.json: add vercel-build = vite build && node scripts/build-vercel-output.mjs
- ui/scripts/build-vercel-output.mjs: emit .vercel/output/config.json with
[ proxy /dashboard/api/* -> $LANGGRAPH_BACKEND_URL, filesystem, SPA fallback ];
throws if LANGGRAPH_BACKEND_URL is unset so a misconfig fails the build.
Keeps the app same-origin (no CORS/auth change); preserves the _shell.html SPA
fallback. Set LANGGRAPH_BACKEND_URL per Vercel project (All Environments).
Enable TanStack Start SPA mode so the build prerenders a static shell
(/_shell.html) and emits a fully static bundle under .output/public,
removing the Nitro serverless function from the Vercel deploy. The
dashboard is a thin client (all data via client-side fetch to the
FastAPI /dashboard/api/*), so SSR rendered nothing of value.
Point Vercel at the static output and add a SPA catch-all rewrite to
the shell for client-side routing, keeping the API proxy rewrite first.
PR #1303 was merged before this URL change landed on the branch. Updates
the rewrite destination from the open-swe-test deployment to the prod
open-swe-v3 deployment so openswe.vercel.app proxies to the right
backend.
Browsers (Safari, Brave, Firefox, increasingly Chrome) refuse to set or
send SameSite=None cookies cross-site. With the frontend on
openswe.vercel.app and the API on *.langgraph.app, the osw_session
cookie from `/auth/callback` was being silently dropped, so every
subsequent /me call returned 401.
Adding a Vercel rewrite makes the API same-origin from the browser's
point of view: the request goes to openswe.vercel.app/dashboard/api/...,
Vercel proxies it to the LangSmith deployment, and the Set-Cookie comes
back attributed to openswe.vercel.app — a first-party cookie that all
browsers honour.
Pair with the matching deployment-side config changes:
- GitHub App callback URL → https://openswe.vercel.app/dashboard/api/auth/callback
- DASHBOARD_API_BASE_URL → https://openswe.vercel.app (LangSmith env)
- VITE_DASHBOARD_API_BASE_URL → unset / empty (Vercel env)
