Taflhouse

A browser-based Hnefatafl game built with Haskell and the Miso framework; compiles to WebAssembly and runs entirely in the browser.

Features

• Game engine — pure Haskell implementation of Hnefatafl rules including movement, captures, shield walls, exit forts, surrounding, and draw detection across 5 board variants.
• AI opponent — minimax search with alpha-beta pruning, configurable difficulty levels.
• Online multiplayer — real-time games via Supabase Realtime. Game state persists in the database; page refreshes and reconnections work naturally.
• Accounts — anonymous or email-based auth via Supabase. Player profiles with display names.
• UI — interactive SVG board with sound effects, move history, and SPA routing.

Board Variants

Variant	Size
Brandubh	7×7
Tablut	9×9
Copenhagen	11×11
Parlett	13×13
Damien Walker	15×15

Prerequisites

# Install Nix
curl -L https://nixos.org/nix/install | sh

# Enable flakes
echo 'experimental-features = nix-command flakes' >> ~/.config/nix/nix.conf

Local Development

# Start local Supabase
make db-start
make db-reset

# Build and serve
nix develop .#wasm --command make
make serve

Open http://localhost:8080.

Push Notifications

Multiplayer games use Web Push to notify players when their opponent moves, even if the browser tab is closed. The flow:

1. A move is written to the games table.
2. A Postgres trigger (notify_push_on_move) fires and calls a Supabase Edge Function via pg_net.
3. The Edge Function reads the opponent's push subscriptions and sends encrypted Web Push messages using VAPID.
4. The browser's Service Worker (sw.js) receives the push event and shows a notification (unless the game tab is already focused).

VAPID Keys

Web Push requires a VAPID key pair to identify the application to push services (Google, Mozilla, Apple). Generate one once and use it across all environments:

npx web-push generate-vapid-keys

This outputs a public key and a private key. Keep the private key secret.

Local Setup

1. .envrc — set the public key so it gets baked into the JS bundle at build time:

   export VAPID_PUBLIC_KEY="<your public key>"
   

2. supabase/.env.local — set secrets for the Edge Function runtime:

   VAPID_PUBLIC_KEY=<your public key>
   VAPID_PRIVATE_KEY=<your private key>
   VAPID_SUBJECT=mailto:hello@taflhouse.com
   

3. Vault secrets — the Postgres trigger reads the Edge Function URL and service role key from Vault. After make db-reset, run in the SQL Editor (http://localhost:54323):

   SELECT vault.create_secret(
     'http://localhost:54321/functions/v1/send-push',
     'push_edge_fn_url'
   );
   SELECT vault.create_secret(
     '<local service_role key from supabase status>',
     'service_role_key'
   );

4. Start Supabase — make db-start serves the Edge Function automatically (no separate supabase functions serve needed). Rebuild the app with make so the VAPID key gets substituted into public/index.js.

Production / Staging Setup

GitHub Actions secrets (set in repo settings):

Secret	Description
PROD_VAPID_PUBLIC_KEY	VAPID public key
STAGING_VAPID_PUBLIC_KEY	VAPID public key
SUPABASE_ACCESS_TOKEN	Personal access token from supabase.com/dashboard/account/tokens, used by supabase functions deploy
PROD_PROJECT_REF	Production project ref (the subdomain of supabase.co)
STAGING_PROJECT_REF	Staging project ref

Supabase Edge Function secrets (per environment):

supabase secrets set \
  VAPID_PUBLIC_KEY="<public key>" \
  VAPID_PRIVATE_KEY="<private key>" \
  VAPID_SUBJECT="mailto:hello@taflhouse.com" \
  --project-ref <project-ref>

Vault secrets (run against each environment's database):

SELECT vault.create_secret(
  'https://<project-ref>.supabase.co/functions/v1/send-push',
  'push_edge_fn_url'
);
SELECT vault.create_secret(
  '<service_role_key>',
  'service_role_key'
);

The service role key is in the Supabase dashboard under Settings > API.

Deployment

Pushes to main deploy to production; pushes to staging deploy to staging. Both go through GitHub Actions which runs Supabase migrations, deploys Edge Functions, and deploys to Cloudflare Workers.

License

BSD3