Claude Code on the Web: Why Your .env Vars Don't Reach the Setup Script (and How SessionStart Hook Fixes It)

TL;DR Environment variables you put in the .env panel of Claude Code on the web (Cloud Sandbox) do not reach the setup script . They only reach the shell inside the running Claude Code session . So git clone "https://x-access-token:${GH_TOKEN}@..." inside the setup script fails — GH_TOKEN is empty at that point. Move the clone into a SessionStart hook and it just works, because by then $GH_TOKEN is populated. This is a write-up of how I narrowed down a behavior that the official docs don't spell