A dropped connection used to hang the whole platform permanently, and three defects composed to do it (BUGS.md B-01): The read loop's death was invisible. When the socket closed, _read_loop broke out and finished, but _run_once was blocked on gather() over two notification consumers waiting on queues nobody would ever fill again — it never returned and never raised, so the reconnect-with-backoff logic was unreachable. client.wait_closed() now resolves when the loop ends for any reason, and _run_once races it against the consumers and a keepalive with asyncio.wait(FIRST_COMPLETED). Nothing had a timeout. request() registered a future, wrote to a half-closed socket (drain() often doesn't raise) and awaited a reply that would never come. That hung a POST /bets *while holding the per-user lock*, and could stop the confirmation poller for good. Every request is now bounded at 15s, and a timeout tears the connection down rather than leaving a server that owes us a reply in rotation. There was no keepalive, so on a quiet instance the normal way this connection dies is an idle-timeout drop by the server (~10 minutes for many). A server.ping every 60s makes that observable within a minute. listener.client is also cleared before reconnecting, so callers stop treating a dead connection as live. On top of the finding, the listener now rotates over a list of servers: ELECTRUM_FALLBACK_SERVERS holds comma-separated host:port[:notls] extras, tried after the primary. Everything the platform does goes through this one connection — deposit credits, broadcasts, confirmations, the chain tip the draw waits on — which made a single hardcoded server its biggest point of failure. A failed or dropped session moves to the next server immediately and only sleeps on the backoff once every server has had a turn, so one dead server costs one attempt instead of an outage, while a genuinely offline network still backs off. A malformed entry fails at startup, not during the outage when the fallback is what you need. Also fixes B-19: header handling refuses a height below the current tip and applies height and hex together, since _wait_for_next_block waits for tip_height > tip_at_close (a regression silently added a block to the draw's wait) and that hex is the draw's entropy source, so a mismatched pair would be worse than a stale one. Verified in the live deployment: the log shows the endpoint list, then "Electrum connected to santantonio.sytes.net:50002", and the connection holds. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
PLM Lottery
A periodic-round lottery system built on PLM, a Bitcoin-like coin (mainnet). Each user gets a dedicated server-derived P2WPKH address; they deposit PLM to that address, place a fixed-cost bet to enter the current round, and when the round closes a winner is drawn who receives 70% of the prize pool (the remaining 30% goes to fees).
This is a custodial system: private keys are generated and held server-side, encrypted at rest. See CLAUDE.md for the full architecture, domain decisions, and known gaps before treating this as production-ready.
Quick start
cp .env.example .env # then fill in the generated secrets, see docs/setup.md
python3 -m venv .venv && source .venv/bin/activate
pip install -e ".[dev]"
PYTHONPATH=. python scripts/generate_master_key.py
alembic upgrade head
uvicorn app.main:app --reload --port 8123
Open http://127.0.0.1:8123/ for the test UI, http://127.0.0.1:8123/admin
for the admin dashboard, http://127.0.0.1:8123/docs for the interactive API
docs.
Or run the whole stack (app + Caddy reverse proxy with automatic TLS) via Docker:
mkdir -p data/db data/keys data/logs
docker compose run --rm app python scripts/generate_master_key.py
docker compose up -d --build
See docs/setup.md and docs/running-the-server.md for the full walkthrough (both workflows, dev vs. production TLS).
Documentation
- CLAUDE.md — architecture, commands, domain decisions, known gaps (for anyone/anything working on the code)
- flowchart.mmd — the source-of-truth flow diagram the implementation follows node-by-node
- docs/setup.md — one-time setup (secrets, master key, migrations)
- docs/running-the-server.md — how to launch it (local venv vs. Docker+Caddy, dev vs. production TLS)
- docs/guida-utente.md — end-user guide to the test UI (Italian)
- docs/guida-admin.md — admin dashboard guide (Italian)
Tech stack
Python (FastAPI, SQLAlchemy async + Alembic, Argon2 + JWT auth), Electrum protocol for PLM network access (no full node), Docker + Caddy for deployment. See CLAUDE.md for the complete list and the reasoning behind each choice.
Testing
python -m pytest # all tests
python -m pytest tests/unit/test_hd.py # one file
76 unit tests cover HD derivation, PSBT building, the Electrum client, bets, deposits, withdrawals, the round/draw engine, RBF fee-bumping, admin config, the pending-inclusive balance calculation, and the SSE push channel. No automated integration tests against a live Electrum connection — mainnet verification so far has been manual (see CLAUDE.md's "Project status").