ScreenNoMore

ScreenNoMore is a self-hosted attention budget enforced through NextDNS. It observes DNS activity for configured services, counts unique minutes of allowed usage in a rolling window, blocks a service when its allowance is reached, and restores access after its cooldown.

Policy

For each service, ScreenNoMore counts a minute once when at least one allowed DNS query matches one of that service's domains. Duplicate queries and blocked queries do not add usage. Only activity inside OBSERVING_LAST_LOGS_FROM_MINUTES and after the most recent cooldown reset is counted.

When limit_minutes is reached, ScreenNoMore enables the matching NextDNS parental-control service. If NextDNS does not know that service ID, its domains are used as denylist fallbacks. After block_duration_minutes, the service is unblocked and its usage is reset.

Run with Docker Compose

1. Copy .env.example to .env.
2. Add the API key from the bottom of the NextDNS account page and the target profile ID.
3. Start the worker:

docker compose up --build -d
docker compose ps
docker compose logs -f app

Stop it intentionally with docker compose down. The unless-stopped restart policy restarts it after crashes and Docker daemon restarts.

The Compose service is healthy after a complete observation cycle succeeds. Repeated cycle failures cause the worker to exit so Docker can restart it.

Configuration

Variable	Purpose	Default in Compose
NEXTDNS_API_KEY	NextDNS API authentication	Required in .env
NEXTDNS_PROFILE_ID	Profile to observe and update	Required in .env
OBSERVING_INTERVAL	Seconds between successful cycles	30
OBSERVING_LAST_LOGS_FROM_MINUTES	Rolling usage window	40
MAX_LOG_PAGES	Pagination safety cap per cycle	20
MAX_CONSECUTIVE_FAILURES	Failures before process restart	5
HEALTH_MAX_AGE_SECONDS	Minimum accepted heartbeat age	90
DATABASE_CONFIG_PATH	SQLite database path	/data/screennomore.db
SERVICES_CONFIG_PATH	First-run service seed file	Included seed JSON

NEXTDNS_API_KEY stays server-side. Do not commit .env or expose it to a future browser client.

Services and persistence

The bundled services.json is read only once to seed a fresh database. After that, SQLite is authoritative: database edits and deletions survive restarts. Each service stores a display name, a NextDNS service ID, monitored domains, an allowance, and a cooldown.

Runtime data is stored in ./data by Compose. Back it up before upgrading:

docker compose down
cp data/screennomore.db data/screennomore.db.backup
docker compose up -d

Startup applies the small additive schema migration needed by this prototype.

Focused checks

The regression checks use Python's standard library:

python -m unittest discover -s tests -v

They cover usage accounting, pagination, cooldown persistence, one-time seeding, remote failure consistency, and the worker failure threshold.

Outlook and TODOs

• In the future there should be a small frontend to view usage and reset cooldowns. For now, use sqlite3 or DB Browser for SQLite to inspect the database.
• Additionally, services.json should be removed in the future, and the database should be the only source of truth.
  • The frontend should then allow adding and removing services.
• There should be a gitlab pipeline for building and publishing the docker image.
• Code quality and test coverage should be improved, especially for the NextDNS API client.
• The NextDNS API client should be moved into its own module, exposing profiles as first-class objects, and the worker should be refactored to use this interface.