LTI 1.3 and SCIM integration for a Next.js and Supabase learning platform

I run a completely new B2B online course platform. Next.js App Router, TypeScript strict, Supabase with row level security, Vercel. Enterprise customers want us connected to their corporate LMS. The first runs Docebo. Two pieces of work: 1. Make our web app an LTI 1.3 tool: the launch handshake, JWKS hosting, and completion posted back to the LMS gradebook through Assignment and Grade Services. Confirm what Docebo actually supports and use the LTI 1.1 outcomes path if AGS is not available. Also an xAPI emitter to a customer's Learning Record Store, and a scheduled completion export carrying participant, course, status, date and hours. 2. WorkOS for enterprise auth: SSO over SAML and OIDC, plus Directory Sync (SCIM) wired into our Supabase user and entitlement model. You must have built the tool side of LTI, not just administered an LMS. Docebo experience is a bonus, not a requirement. In your first message, could you kindly answer this: a tool posts a completion to a platform's gradebook over LTI 1.3. What has to be in place for that call to succeed, and what are the two most common reasons it fails in production? Send your rate, availability, and describe one LTI project you shipped.