langsmith-custom-apps

<agents_md_is_authoritative> langsmith apps init scaffolds an AGENTS.md next to the starter code. That file is the authority on the in-app contract — the window.langsmith.call bridge, the render() export the sandbox depends on, the filter DSL, and the endpoint menu. Read it before writing app code and follow it over anything remembered.

This skill deliberately does not restate it. Everything here is what AGENTS.md cannot cover: what happens before the directory exists, and after the app is pushed. </agents_md_is_authoritative>

export LANGSMITH_ENDPOINT=<your-langsmith-endpoint>   # only for self-hosted
export LANGSMITH_API_KEY=<workspace-api-key>

Three authentication traps, each of which presents as something other than an auth problem: