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Configuration reference

Sparkth reads its configuration from environment variables. For how to set and update them (.env vs .env.local, precedence, applying changes), see the configuration guide.

The .env file is the source of truth

.env is committed and carries a comment on every variable the application reads, together with its dev default. It is the authoritative, always-current list — consult it for the complete set of variables (database and Redis URLs, secret keys, SMTP settings, Google OAuth, chat tuning, and more). This page documents only the variables that need narrative beyond that inline comment.

Feature flags

REGISTRATION_ENABLED

  • Type: boolean (true / false)
  • Default: false

Controls whether new user registration is enabled on the frontend.

  • If REGISTRATION_ENABLED=true, users can sign up via the frontend.
  • If REGISTRATION_ENABLED=false, the registration form is disabled, preventing new user creation. Accounts are then created out-of-band — see the user management guide.

Changing this flag does not affect existing users.

SERVE_FRONTEND

  • Type: boolean (true / false)
  • Default: false

Controls whether the backend serves the static frontend export (FRONTEND_DIR, default frontend/out) at /.

  • If SERVE_FRONTEND=true, the backend serves the frontend on its own port — the single-container production setup. The production image sets this via ENV in the Dockerfile. Startup fails if the export directory is missing: build it first with make frontend.build.
  • If SERVE_FRONTEND=false, the backend serves only the API and MCP endpoints. This is the dev default: use the Next.js dev server on :3000, which proxies /api to the backend. It also prevents a leftover local frontend/out build from being served stale.

Language

DEFAULT_LANGUAGE

The platform-wide default interface language: the fallback value for users who have not chosen one in their profile and whose browser offers no supported language. A BCP 47 tag, and it must be one of the supported languages — en, es or fr. Anything else fails validation at startup rather than being silently accepted.

Defaults to en. The interface locale follows a precedence chain: a signed-in user's stored language preference, when set and still one of the supported languages, is bound by the authentication dependency once the user is resolved, and wins over everything else; otherwise the locale middleware's negotiation of the Accept-Language header applies; DEFAULT_LANGUAGE is the last resort, used when neither offers a supported tag and outside any request (background tasks, CLI). See the translations guide.

This governs interface text only. The language of AI-generated replies and course content is inferred from the conversation and is not constrained by this setting or by the supported-languages list.