docker/.env feeds MERCURE_EXTRA_DIRECTIVES, a Caddyfile-style config block, via Compose variable substitution. Quoting a space-separated value there makes Caddy treat both origins as one single malformed token rather than two arguments, which crash-loops the Mercure container on startup. Compose's .env parsing for values with spaces doesn't require quotes (unlike Symfony's Dotenv), so drop them. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>