Fix preview build Convex site URL

Author: prazgaitis

tasks/2026-02-11-preview-deploy-convex-site-url.md

@@ -0,0 +1,5 @@
+# 2026-02-11: Fix preview deploy missing CONVEX_SITE_URL
+
+- [x] Reproduce and locate the missing env var usage
+- [x] Update Vercel build command to set `NEXT_PUBLIC_CONVEX_SITE_URL`
+- [x] Summarize the fix and any required deploy env changes

vercel.json

@@ -1,6 +1,6 @@
 {
   "$schema": "https://openapi.vercel.sh/vercel.json",
-  "buildCommand": "cd ../../packages/backend && npx convex deploy --cmd 'cd ../../apps/web && npx next build' --cmd-url-env-var-name NEXT_PUBLIC_CONVEX_URL",
+  "buildCommand": "cd ../../packages/backend && npx convex deploy --cmd \"NEXT_PUBLIC_CONVEX_SITE_URL=$(printf %s \\\"$NEXT_PUBLIC_CONVEX_URL\\\" | sed 's/\\\\.convex\\\\.cloud/.convex.site/'); cd ../../apps/web && npx next build\" --cmd-url-env-var-name NEXT_PUBLIC_CONVEX_URL",
   "installCommand": "pnpm install",
   "framework": "nextjs"
 }