6 confirmed findings (review wqrd2gka3), 3 root-cause fixes:
- HIGH: execute_erasure had no status recheck and the sweeper's SKIP LOCKED row
lock was released before execution (separate connection), so (a) a request
CANCELLED after the sweep's SELECT was still executed, and (b) a fleet could
double-execute one erasure (duplicate hash-chained audit row, double count).
Fixed by making execution atomically CLAIM the row as its first statement —
`UPDATE ... SET status='completed' WHERE id=$1 AND status='confirmed'
RETURNING user_id` — and skipping (returns false) when 0 rows match. Only the
first executor of a still-confirmed request proceeds; a cancelled/already-done
row is a no-op; on any later failure the whole tx (claim included) rolls back.
- account-existence oracle: the absent-user request path returned a FRESH random
erasure_id + advancing scheduled_for each call, while a real account returned a
STABLE get-or-create id — a re-call distinguisher. The request response is now
constant-shape: a STABLE id (real, or a deterministic integrity-secret-keyed
synthetic for the absent path), a fixed "pending" status, and NO scheduled_for
(it's meaningful only at confirm, where grace starts, and is returned there).
- config: ERASURE_GRACE_PERIOD_HOURS is bounded (<= 10 years) in validate(), so
the u64->i64 cast can't wrap negative (defeating grace) and Duration::hours
can't panic.
Dismissed after verification: ERASURE_ENABLED without FEATURE_NOSTR_IDENTITY
(validate already requires PUBLIC_API_URL; the nostr_identity coupling is a
nicety). Tests extended: cancelled-request-not-executed (HIGH regression),
double-execute no-op. 140 lib + 140 integration green, no drift, scans clean.
The last operator subsystem: a user who no longer trusts the backend can reach in
and delete their data. Action-bound and two-phase.
- migration 20260626000003: erasure_requests (user_id ON DELETE SET NULL so the
completed tombstone survives the user delete; one-live-request-per-user partial
unique index; due index).
- Proof model (§5.2): every action is a fresh NIP-98 signed action (purpose
erasure_request/confirm/cancel/export) bound to a single-use challenge nonce +
canonical descriptor + (confirm/cancel) the explicit erasure_id. A session
token is NEVER sufficient. Erasure targets only the users.id the proof's key
resolves to (via linked nostr_pubkey); leaked identifiers are never selectors.
Nonce consumed AFTER signature checks (forged sig can't burn a victim's nonce).
- Public routes (proof-gated): POST /account/erasure/challenge, /account/erasure
(request; ABSENT-user path returns identical shape — no account-existence
oracle), /account/erasure/:id/confirm (revokes live sessions), DELETE
/account/erasure/:id (cancel during grace), POST /account/export (see-before-
delete; omits view keys; audited).
- Execution (§5.7): a background sweeper claims confirmed-past-grace rows
(FOR UPDATE SKIP LOCKED) and runs ONE fail-closed tx: purge login_events
(the origin/asset/time quasi-identifier; default) or anonymize; scrub audit
PII; DELETE users (schema cascades wallets/sessions/keys/owned slatepacks,
SET NULL on counterparty/audit/login links); tombstone; hash-chained
account_erasure_completed audit.
- config: ERASURE_GRACE_PERIOD_HOURS (72h default); validate() requires the
integrity secret + PUBLIC_API_URL when erasure is enabled.
- 1 L1 test: export -> request -> confirm -> execute -> account gone, plus the
absent-user constant-shape path.
Scope (v1, documented): live primary. No at-rest view key exists to crypto-shred
(stateless-forward), so backup residue is bounded by retention-window docs, not
crypto-shred (non-v1 per decisions ledger). Deferred: LWS de-registration queue +
read-back probe (operators run their own LWS), audit cross-reference scrub on
OTHER users' rows, restore_attempt salted-rotated fingerprint, retention sweepers,
NIP-17 DM warning, in-flight-value blockers (no swaps/tips in the clean core),
hard per-day export rate cap, /admin/erasure/stuck observability. Routes are off
the public OpenAPI for now (stable contract; annotate later).
jwinterm