plm-lottery/BUGS.md

# Known bugs

A second full-codebase audit on 2026-07-27 found **25 further issues** (4 critical, 6 high,
7 medium, 8 low), listed below as B-33 … B-49. B-25 through B-35 are fixed (see "Previously
fixed" below) — no Critical-severity finding remains open; the other 14 are High/Medium/Low.
The 139-test suite was green at the time of the audit, so none of these were caught by existing
coverage — every fix lands with a regression test (the eleven fixes so far brought the suite
from 139 to 198).

The recurring pattern across the open findings is worth stating once: the code is rigorous
about the failure modes that have actually been hit, and silent about the ones that have not.
The payout phase is now fully recoverable; the "drawing" phase (waiting on a block) still has
no equivalent resume-after-restart or stall visibility (B-36).

For limitations that are accepted by design rather than bugs (single-shared-token admin auth,
single-process assumptions, no user-facing history, etc.), see "Known gaps / TODO" in
[CLAUDE.md](CLAUDE.md).

---

## Medium

### B-36 — `_wait_for_next_block` waits forever, with no timeout and no visibility

`rounds/scheduler.py:158-161` loops until a higher block arrives. No timeout, no log, no audit
entry. If the connection dies in a way that stops the tip advancing, the round sits in
`drawing` indefinitely and **the admin panel shows nothing at all** — just a frozen state with
no explanation.

**Proposed fix.** Log progress periodically while waiting, and past a threshold (a few
multiples of the 120s block time) write a `draw_stalled` audit entry so it surfaces in
`/admin`. Surface the wait in `GET /rounds/current` too (it already returns
`chain_tip_height`; `draw_waiting_since` would make the stall self-evident to users).

### B-37 — Displayed balance and spendable balance diverge, and the error does not explain it

After a bet the change is unconfirmed, so `cached_balance_sats` ≈ 0 while the UI shows
`pending_balance_sats` (the real figure). A withdrawal attempted right after validates against
**confirmed** UTXOs (`withdrawals/service.py:54-60`) and answers `insufficient_balance`.

The user sees "1.000 PLM" on screen and is told they have no funds. The mechanism is a
documented design decision, but the error does not distinguish "you don't have the money" from
"your money is waiting to confirm" — two very different situations for whoever reads it.

**Proposed fix.** A distinct error code (e.g. `balance_pending_confirmation`) raised when the
requested amount is covered by `pending_balance_sats` but not by the confirmed balance,
carrying the pending amount in `params`, plus its `error.*` entry in all 7 languages. The
withdrawal form should also cap/hint the max against the confirmed balance rather than the
displayed one.

### B-38 — The 500-subscriber SSE cap is a zero-cost DoS of the realtime feature

`GET /rounds/stream` requires no authentication and each connection takes a slot on a
**global** counter (`rounds/events.py:33-38`). Anyone opening 500 connections degrades every
real user to polling. The comment describes it as a defensive cap; it is in fact the vector,
not the defence.

**Proposed fix.** Cap per client IP (and, once available, per authenticated user) rather than
globally, and evict the oldest idle subscriber instead of refusing new ones. The reverse proxy
is the right place for the connection-count limit — Caddy can enforce it before the request
reaches the app.

### B-39 — SQLite with no WAL, no `busy_timeout`, and five concurrent writer tasks

`db/base.py:6` calls `create_async_engine(settings.database_url)` with no `connect_args`, and
there is no `PRAGMA` anywhere in the repo (verified by grep). Without `journal_mode=WAL`
readers block writers, and the concurrent writers are five background tasks plus every HTTP
handler. `database is locked` under load is realistic, and nothing handles it.

**Proposed fix.** Set `journal_mode=WAL`, `synchronous=NORMAL` and a `busy_timeout` of a few
seconds on connect (a `connect` event listener on the engine, applied only for the SQLite
dialect), and retry `OperationalError: database is locked` in the background loops. Longer
term this is an argument for PostgreSQL, which the single-process constraints in CLAUDE.md
also point at.

### B-40 — `bump_fee` holds a DB session open across N network calls

`tx/broadcast.py:80` issues one `get_transaction` **per input** (up to 15s each) and then a
`broadcast`, all with the session open. This is precisely the pattern B-18 removed from
`_trigger_payout` via its three-phase structure; it survives here.

Side note in the same function: `_prevout_amount` does `round(value_coins * 100_000_000)` on a
float from the server — acceptable at these magnitudes, but it is floating-point money
arithmetic in a codebase that is otherwise strictly integer-satoshi.

**Proposed fix.** Restructure into the same three phases: read what is needed and close the
session, do the chain work, then reopen to persist. For the float: prefer the raw (non-verbose)
transaction and parse the output value as an integer with `embit`, which is what
`reconcile.py:_release_inputs` already does for inputs.

### B-41 — All confirmation logic depends on `verbose=True`, which is not universally supported

`poll_once`, `reconcile._tx_exists_on_chain` and `bump_fee` all call
`blockchain.transaction.get(txid, True)`. Several Electrum server implementations and versions
reject the verbose flag ("verbose transactions are currently unsupported"). Falling back onto
such a server means **no confirmations, no reconciliation, no bumps** — and the code would read
that as a transport error and stay silent.

Related: `reconcile.py:83` decides whether to **abandon a transaction** by substring-matching
the error text (`"missing"`, `"not found"`, `"no such"`, `"unknown"`). It works against
ElectrumX; it is fragile as the basis for a decision that releases funds.

**Proposed fix.** Use `blockchain.transaction.get_merkle` (or the scripthash history) for
confirmation and existence checks — both are portable and give the confirming height directly.
Probe verbose support once at connect time and record it on the client, so an unsupported
server is detected loudly at session start rather than silently mid-operation.

---

## Low / hygiene

### B-42 — `/docs` exposed in production

FastAPI mounts Swagger by default, so the entire API surface — `/admin` included — is publicly
enumerable. The README advertises it.
**Fix:** `docs_url=None, redoc_url=None, openapi_url=None` in production (env-gated), or place
them behind `require_admin`.

### B-43 — No HTTP security headers

The [Caddyfile](Caddyfile) sets no CSP, no `X-Frame-Options`/`frame-ancestors`, and no HSTS
(Caddy does not add it on its own). The JWT lives in `localStorage`, so any XSS exfiltrates
it, and the page is iframeable.
**Fix:** a `header` block in the Caddyfile with `Strict-Transport-Security`,
`X-Content-Type-Options: nosniff`, `Referrer-Policy` and a CSP tight enough for two static
pages with no external assets (`default-src 'self'`).

### B-44 — README and CLAUDE.md contradict each other

The README says to run `uvicorn --reload` directly and
`docker compose run --rm app python scripts/generate_master_key.py`; CLAUDE.md says explicitly
that neither is supported. Whoever opens the repo reads the README first.
**Fix:** align the README's Quick start with the Docker-only workflow documented in
CLAUDE.md and `docs/setup.md`.

### B-45 — Unvalidated and unpaginated admin list endpoints

`limit: int = 50` on `/admin/rounds` and `/admin/audit-log` has no bounds (`-1` means
"everything" on SQLite), and `/admin/pending-transactions` has no limit at all — it grows
without end.
**Fix:** `Query(default=50, ge=1, le=500)` on both, and the same treatment plus a status filter
on the pending-transaction list.

### B-46 — `secrets.compare_digest` on a `str` raises on non-ASCII input

`api/routes/admin.py:27` raises `TypeError` — a 500 instead of a 403 — when the header contains
non-ASCII characters.
**Fix:** compare the UTF-8 encoded bytes of both sides.

### B-47 — Unbounded `String` columns for large text

`raw_tx_hex` (`db/models.py:146`) and `payload_json` (`:178`) should be `Text`. It works on
SQLite and PostgreSQL and breaks elsewhere.
**Fix:** switch both to `Text` in a migration.

### B-48 — No cap on input count in `select_utxos`

A user with hundreds of small UTXOs builds a huge transaction whose fee — deducted from the bet
amount — materially erodes their contribution to the pool, and it can exceed standardness
limits.
**Fix:** cap the selected inputs (e.g. 50) and fail with a translatable error suggesting a
consolidation, or consolidate the address automatically when the count crosses a threshold.

### B-49 — Rollback paths do not publish an SSE update

`bets/service.py:_release_failed_bet` and `withdrawals/service.py:_release_failed_withdrawal`
restore the balance without calling `broadcaster.publish()`, so dashboards only find out on
their next poll.
**Fix:** one `broadcaster.publish()` at the end of each, as every other state-changing path
already does.

---

## Previously fixed

- **B-25** — the payout had no two-phase write, unlike bets and withdrawals
- **B-26** — a payout failure or a process restart could wedge a round in `paying_out` forever
- **B-27** — an RBF bump reset the reconciler's own abandon clock, so a repeatedly-bumped tx was never abandoned
- **B-28** — a hostile Electrum server (or a MITM) could single-handedly pick the round's winner
- **B-29** — a UTXO absent from one server's `listunspent` was marked spent immediately, irreversibly, on a single unauthenticated reply
- **B-30** — a lost scripthash subscription meant a user's deposits were never credited, with no periodic safety net
- **B-31** — resubscribing on reconnect ran serially before anything else started, freezing the chain tip (and so an in-flight draw) for the whole sweep
- **B-32** — an RBF bump could retry forever below BIP125's relay-mandated minimum fee delta, with no ceiling on the fee rate either
- **B-33** — `POST /auth/login` had no rate limiting, so a password could be brute-forced against an enumerable username list
- **B-34** — password change/reset didn't invalidate already-issued JWTs, so a stolen token survived a change meant to lock it out
- **B-35** — API timestamps round-tripped as naive datetimes, so the frontend parsed them as local time instead of UTC

See git history for the fix-by-fix breakdown (commits `f13f685`, `50a43ae`, `933760e`, and the
B-28/B-29/B-30/B-31/B-32/B-33/B-34/B-35 fixes). Suite grew from 139 to 198 tests over the eleven.

A full-codebase audit on 2026-07-26 (commit `d4e0974`) found 24 bugs across every Python
module under `app/`, both static frontends, and the Docker/Caddy deployment — 5 critical,
7 high, 7 medium, 5 low. All 24 were fixed and verified against the current code on
2026-07-27; the fixes are covered by the regression suite (grew from 79 to 139 tests) and
five of them were additionally confirmed against a real mainnet deployment (see git history
between `fb734bb` (documenting the findings) and `845ba98` (recording the audit outcome) for
the fix-by-fix breakdown — each commit message names the bugs it closes and where their
tests live).