contracts: bound chklocks' sweep (epoch-stall risk) + materialize the per-bucket locked total

contracts/sysio.epoch/src/sysio.epoch.cpp

@@ -4,8 +4,9 @@
 #include <sysio.opp.common/opp_keys.hpp>
 #include <sysio.authex/sysio.authex.hpp>
 #include <sysio.token/sysio.token.hpp>
-// For uwrit::MAX_UWREQ_PRUNE_PER_EPOCH — the per-epoch budget advance hands
-// to the inline `pruneuwreqs` sweep (the constant is owned by sysio.uwrit).
+// For uwrit::MAX_LOCK_RELEASE_PER_EPOCH and uwrit::MAX_UWREQ_PRUNE_PER_EPOCH —
+// the per-epoch budgets advance hands to the inline `chklocks` and
+// `pruneuwreqs` sweeps (both constants are owned by sysio.uwrit).
 #include <sysio.uwrit/sysio.uwrit.hpp>
 // For reserve::MAX_CLAIM_SWEEP_PER_EPOCH — the per-epoch budget advance hands
 // to the inline `sweepclaims` retention sweep (the constant is owned by
@@ -414,7 +415,7 @@ void epoch::advance() {
       permission_level{get_self(), "owner"_n},
       UWRIT_ACCOUNT,
       "chklocks"_n,
-      std::make_tuple()
+      std::make_tuple(uwrit::MAX_LOCK_RELEASE_PER_EPOCH)
    ).send();
 
    // Bounded UWREQ lifecycle sweep (SEC-129 / WSA-223): erase terminal

contracts/sysio.opreg/src/sysio.opreg.cpp

@@ -370,28 +370,23 @@ void opreg::regoperator(name account,
 
 namespace {
 
-/// Sum the active locks on `sysio.uwrit::locks` for a given (op, chain, token).
-/// Returns 0 if uwrit's locks table is empty or if the operator has no locks
-/// on that chain/token.
+/// The active lock total on `sysio.uwrit` for a given (op, chain, token) —
+/// an O(1) read of uwrit's `locksums` rollup. Returns 0 when the operator
+/// holds no live locks on that chain/token (the rollup erases a bucket's row
+/// once it empties, so an absent row IS zero).
 ///
-/// Per v6 plan §B.2 (split-index design): `sysio.uwrit::locks_t` exposes only
-/// uint64 secondary indexes. The `byuw` index keys on `underwriter.value`;
-/// rows are filtered on `(chain_code, token_code)` in memory. Per-underwriter
-/// lock counts are O(1)-ish in steady state so the scan is cheap.
+/// This used to scan `sysio.uwrit::locks` through its `byuw` index and filter
+/// `(chain_code, token_code)` in memory, on the stated assumption that
+/// per-underwriter lock counts are "O(1)-ish in steady state so the scan is
+/// cheap". That assumption does not hold: uwrit locks are held for the full
+/// wall-clock challenge window and are never released by delivery, so a
+/// bucket's live lock count is (settlement rate × lock duration). uwrit now
+/// maintains the total at the two sites that can change it; see
+/// `uwrit::lock_sum`.
 uint64_t sum_locks_inline(name account, sysio::slug_name chain_code, sysio::slug_name token_code) {
-   uwrit::locks_t locks(opreg::UWRIT_ACCOUNT);
-   auto idx = locks.template get_index<"byuw"_n>();
-
-   uint64_t total = 0;
-   auto it  = idx.lower_bound(account.value);
-   auto end = idx.upper_bound(account.value);
-   for (; it != end; ++it) {
-      if (it->chain_code != chain_code || it->token_code != token_code) continue;
-      // Saturating: amounts are uncapped uint64 (external-chain values); a
-      // wrapped subtotal would understate `reserved` and overstate availability.
-      total = opp::safe::add_sat_u64(total, it->amount);
-   }
-   return total;
+   uwrit::locksums_t sums(opreg::UWRIT_ACCOUNT);
+   uwrit::lock_sum_key pk{account, chain_code, token_code};
+   return sums.contains(pk) ? sums.get(pk).amount : 0;
 }
 
 /// Sum the pending (not-yet-flushed) withdraws on this contract for a given

contracts/sysio.uwrit/README.md

@@ -12,8 +12,11 @@ rate every swap is charged.
   against their WIRE account permissions, re-runs the LP variance check,
   re-checks available collateral, then picks a winner.
 - Writes one collateral lock per required leg and holds it for the full
-  wall-clock challenge window. **Locks are never released by delivery** — only
-  `chklocks` sweeps them once `expires_at_ms` passes.
+  wall-clock challenge window. **Locks are never released by delivery** — on the
+  healthy path only `chklocks` sweeps them, once `expires_at_ms` passes. An
+  UPHELD underwriter-fault challenge ends the window early instead: `sweeplocks`
+  erases that commitment's locks where they stand, which can be well before
+  `expires_at_ms`.
 - Settles the winning swap against `sysio.reserv` and queues the outbound
   `SWAP_REMIT`.
 - Escrows and drains swap-from-WIRE requests (`fwqueue`), charging a revert fee
@@ -63,8 +66,9 @@ chain deregistered) refund in full.
 | Table | Row type | Description |
 |-------|----------|-------------|
 | `uwconfig` | `uw_config` | Singleton: `fee_bps`, `collateral_lock_duration_ms`, `min_fromwire_amount`, `fromwire_revert_fee_bps`, `uwreq_pending_timeout_epochs`, `uwreq_retention_epochs` |
-| `uwreqs` | `uw_request_t` | One row per swap intent — race state in `commits_by`, `winner`, lifecycle status, mirrored `variance_tolerance_bps`. Retained for `uwreq_retention_epochs` after ANY terminal transition — `COMPLETED` (after `chklocks` sweeps the final collateral lock; the reserve settlement itself already happened at winner selection, which is what made the row CONFIRMED), `REJECTED` (immediate failure via `reject_and_refund`), or `EXPIRED` (pending timeout, same path) — then erased by `pruneuwreqs` |
-| `locks` | `lock_entry` | Flat per-leg lock vector consulted by `sysio.opreg::available()`. The `byexpire` secondary index lets `chklocks` sweep expired locks in one pass |
+| `uwreqs` | `uw_request_t` | One row per swap intent — race state in `commits_by`, `winner`, lifecycle status, mirrored `variance_tolerance_bps`. Retained for `uwreq_retention_epochs` after ANY terminal transition — `COMPLETED` (once the last collateral lock is gone — normally when `chklocks` sweeps it at expiry, but earlier when `sweeplocks` erases it on an UPHELD challenge; both run the same `finalize_settled_uwreqs` tail. The reserve settlement itself already happened at winner selection, which is what made the row CONFIRMED), `REJECTED` (immediate failure via `reject_and_refund`), or `EXPIRED` (pending timeout, same path) — then erased by `pruneuwreqs` |
+| `locks` | `lock_entry` | Flat per-leg lock vector consulted by `sysio.opreg::available()`. The `byexpire` secondary index lets `chklocks` sweep expired locks oldest-first, up to its per-epoch budget |
+| `locksums` | `lock_sum` | Materialized Σ `lock_entry.amount` per `(underwriter, chain_code, token_code)` bucket — the "locked" half of `sysio.opreg::available()`, read O(1) instead of scanning `locks`. Written by exactly three paths, all in this contract: `try_select_winner` ADDS (on a win), `chklocks` DECREMENTS (healthy release at expiry), and `sweeplocks` DECREMENTS (erasing a commitment's held locks on an UPHELD challenge). A bucket's row is erased once its total reaches zero, so an absent row reads as zero. Any new erase path must decrement too — the rollup is authoritative for `available()`, so a bucket left positive after its last row is gone suppresses that collateral permanently |
 | `fwqueue` | `fromwire_q` | Escrowed swap-from-WIRE requests awaiting drain. `byepoch` secondary index |
 | `uwcounters` | `uw_counters` | Monotonic id allocators (uwreq ids, lock ids) |
 
@@ -77,8 +81,11 @@ chain deregistered) refund in full.
 | `rcrdcommit` | `sysio.msgch` | Record an underwriter's per-leg `UNDERWRITE_INTENT_COMMIT` bytes; resolves the race once both legs are present |
 | `swapfromwire` | `user` | Escrow WIRE and enqueue a swap-FROM-WIRE request |
 | `drainfwq` | `sysio.epoch` or self | Drain the from-WIRE queue: settle what prices, revert the rest (charging the revert fee on caller-fault causes) |
-| `chklocks` | `sysio.epoch` or self | Sweep collateral locks whose wall-clock window has expired |
+| `chklocks` | `sysio.epoch` or self | Sweep collateral locks whose wall-clock window has expired, oldest-first, EXAMINING at most `max_rows` rows per call (`advance` passes `MAX_LOCK_RELEASE_PER_EPOCH`) — the budget counts rows examined rather than locks released, so held locks and the challenge pokes they generate are bounded by it too; an oversized expiry burst drains across later epochs rather than aborting `advance` |
 | `pruneuwreqs` | `sysio.epoch` or self | Expire timed-out PENDING uwreqs and erase terminal rows past their retention window |
+| `holdlocks` | `sysio.chalg` | Mark a commitment's winning locks as held by an OPEN underwriter-fault challenge (WIRE-297); held locks are skipped by `chklocks` instead of released |
+| `freelocks` | `sysio.chalg` | Clear the hold after a REJECTED or LAPSED challenge, so the next `chklocks` releases the locks normally |
+| `sweeplocks` | `sysio.chalg` | Erase a commitment's held locks after an UPHELD challenge — the underwriter is already SLASHED, so each `releaselock` takes its deferred-slash branch. Decrements `locksums` like `chklocks` does |
 | `sumlocks` | read-only | Sum an underwriter's active locks for a `(chain, token)` bucket — the lock half of `sysio.opreg::available()` |
 
 ## Dependencies