feat(ops): track broker balance worker failure lifecycle and backoff

Co-authored-by: genichin <4282227+genichin@users.noreply.github.com>

tests/adapters/broker/test_kis.py

@@ -59,7 +59,8 @@ def test_account_scope_hash_separates_endpoint_and_application_identity():
         (403, "authorization_failed"),
         (422, "broker_rejected"),
         (429, "transport_failed"),
-        (500, "transport_failed"),
+        (500, "http_5xx"),
+        (504, "timeout"),
         (None, "broker_rejected"),
     ],
 )
@@ -350,8 +351,8 @@ def test_get_balance_fails_closed_on_later_transport_and_http_errors(monkeypatch
     request = httpx.Request("GET", "https://example.test/balance")
     response = httpx.Response(503, request=request)
     for failure, expected_code in [
-        (httpx.ConnectTimeout("unavailable"), "transport_failed"),
-        (httpx.HTTPStatusError("bad gateway", request=request, response=response), "transport_failed"),
+        (httpx.ConnectTimeout("unavailable"), "timeout"),
+        (httpx.HTTPStatusError("bad gateway", request=request, response=response), "http_5xx"),
     ]:
         broker, calls = _balance_broker(monkeypatch, [
             _BalanceResponse(_balance_payload([{"pdno": "005930", "hldg_qty": "2"}], fk="A", nk="1"), "F"),
@@ -407,6 +408,29 @@ def test_get_available_cash_uses_cash_only_amount(monkeypatch):
     assert b.get_available_cash() == 695_591
 
 
+@pytest.mark.parametrize(
+    ("failure", "expected_code"),
+    [
+        (httpx.ReadTimeout("timed out"), "timeout"),
+        (
+            httpx.HTTPStatusError(
+                "bad gateway",
+                request=httpx.Request("GET", "https://example.test"),
+                response=httpx.Response(502, request=httpx.Request("GET", "https://example.test")),
+            ),
+            "http_5xx",
+        ),
+    ],
+)
+def test_get_available_cash_classifies_timeout_and_http_5xx(monkeypatch, failure, expected_code):
+    b = KISBroker("12345678-01", app_key="k", app_secret="s", base_url=_MOCK_URL)
+    monkeypatch.setattr(b, "_headers", lambda _tr: {})
+    monkeypatch.setattr("trex_core.adapters.broker.kis.httpx.get", lambda *a, **kw: (_ for _ in ()).throw(failure))
+    with pytest.raises(BrokerBalanceError) as raised:
+        b.get_available_cash()
+    assert raised.value.code == expected_code
+
+
 def test_submit_transport_failure_blocks_automatic_duplicate(monkeypatch):
     b = KISBroker("12345678-01", app_key="k", app_secret="s", base_url=_MOCK_URL)
     monkeypatch.setattr(b, "_headers", lambda _tr: {})

tests/application/test_execution.py

@@ -5,8 +5,11 @@ In-memory adapters; deterministic paper double drives the full async path.
 
 from __future__ import annotations
 
+from datetime import UTC, datetime, timedelta
+
 from trex_core.adapters.broker.paper import PaperBroker
 from trex_core.adapters.persistence.in_memory_intent_store import InMemoryIntentStore
+from trex_core.application.account_snapshot import AccountSnapshotUnavailable
 from trex_core.application.broker_port import (
     BalanceItem,
     CancelOutcome,
@@ -214,6 +217,61 @@ def test_pending_sell_uses_injected_bounded_balance_reader():
     assert repo.fetch_slot(sid).status is SlotState.PENDING_SELL
 
 
+def test_pending_sell_balance_failure_is_fail_closed_with_backoff_and_recovery():
+    now = {"t": datetime(2026, 9, 12, tzinfo=UTC)}
+    broker = PaperBroker(fill_after_polls=0)
+    repo, svc, intents, _ = _wire(broker)
+    sid = _buy(intents, qty=3).slot_id
+
+    execution = ExecutionService(
+        svc,
+        repo,
+        broker,
+        instance_key=INST,
+        clock=lambda: now["t"],
+    )
+    execution.run_once()
+    svc.sell(sid, actor="t", reason="full")
+    broker._fill_after = 5
+
+    calls = {"n": 0}
+    reader_state = {"ok": False}
+
+    def failing_reader():
+        calls["n"] += 1
+        if not reader_state["ok"]:
+            raise AccountSnapshotUnavailable("expired")
+        return [BalanceItem("005931", 3)]
+
+    execution = ExecutionService(
+        svc,
+        repo,
+        broker,
+        instance_key=INST,
+        balance_reader=failing_reader,
+        clock=lambda: now["t"],
+    )
+    first = execution.run_once()
+    assert first.sell_skipped_no_balance == 1
+    assert calls["n"] == 1
+    health = execution.balance_worker_health(stale_after_sec=600)
+    assert health["state"] == "unavailable"
+    assert health["failure_code"] == "stale_snapshot"
+    assert health["consecutive_failures"] == 1
+
+    second = execution.run_once()
+    assert second.sell_skipped_no_balance == 1
+    assert calls["n"] == 1  # bounded backoff prevented another live read
+
+    now["t"] += timedelta(seconds=16)
+    reader_state["ok"] = True
+    third = execution.run_once()
+    assert third.dispatched == 1
+    health = execution.balance_worker_health(stale_after_sec=600)
+    assert health["state"] == "ok"
+    assert health["consecutive_failures"] == 0
+
+
 def test_partial_sell_qty_is_min_intent_broker():
     """dcy-021/REQ-062 (D4): partial sell dispatches min(intent qty, broker);
     remainder stays holding (broker-authoritative qty), cost basis preserved."""

tests/application/test_snapshot_scheduler.py

@@ -665,3 +665,60 @@ def test_build_kis_reinit_callback_returns_callable_for_kis():
     result(new_cred)
     assert broker._account_ref == "new-acct"
     assert broker._app_key == "new-k"
+
+
+def test_balance_worker_health_isolated_backoff_and_recovery():
+    from trex_core.application.broker_port import BalanceItem, BrokerBalanceError
+    from trex_core.domain.slot import SlotService
+    from trex_core.domain.slot.in_memory_repository import InMemorySlotRepository
+
+    class SequencedBroker(PaperBroker):
+        def __init__(self):
+            super().__init__()
+            self.steps = []
+
+        def get_balance(self):
+            if not self.steps:
+                return []
+            step = self.steps.pop(0)
+            if isinstance(step, Exception):
+                raise step
+            return step
+
+    now = {"t": datetime(2026, 9, 12, 0, 0, tzinfo=timezone.utc)}
+    read = _make_stub()
+    store = SnapshotStore()
+    slot_repo = InMemorySlotRepository()
+    slot_service = SlotService(slot_repo, instance_key="default")
+    slot_repo.reconcile_universe("default", {"pf-X": "X"})
+    broker = SequencedBroker()
+    sched = SnapshotScheduler(
+        read_port=read,
+        store=store,
+        broker=broker,
+        slot_repo=slot_repo,
+        slot_service=slot_service,
+        clock=lambda: now["t"],
+    )
+
+    broker.steps = [BrokerBalanceError("http_5xx"), [BalanceItem("X", 0)]]
+    assert sched.run_once() is True
+    state = sched.balance_worker_health(stale_after_sec=86_400)
+    assert state["position_reconciliation"]["state"] == "unavailable"
+    assert state["position_reconciliation"]["failure_code"] == "http_5xx"
+    assert state["position_reconciliation"]["consecutive_failures"] == 1
+    assert state["core_holding_reconciliation"]["state"] == "ok"
+
+    broker.steps = [[BalanceItem("X", 0)]]
+    assert sched.run_once() is True
+    assert broker.steps == []  # position worker stayed in backoff, core worker still ran
+    state = sched.balance_worker_health(stale_after_sec=86_400)
+    assert state["position_reconciliation"]["consecutive_failures"] == 1
+    assert state["core_holding_reconciliation"]["state"] == "ok"
+
+    now["t"] += timedelta(seconds=16)
+    broker.steps = [[BalanceItem("X", 0)], [BalanceItem("X", 0)]]
+    assert sched.run_once() is True
+    state = sched.balance_worker_health(stale_after_sec=86_400)
+    assert state["position_reconciliation"]["state"] == "ok"
+    assert state["position_reconciliation"]["consecutive_failures"] == 0

trex_core/adapters/broker/kis.py

@@ -54,7 +54,11 @@ def _balance_http_error_code(status: int | None) -> str:
         return "authentication_failed"
     if status == 403:
         return "authorization_failed"
-    if status in {408, 425, 429} or (status is not None and status >= 500):
+    if status in {408, 504}:
+        return "timeout"
+    if status is not None and status >= 500:
+        return "http_5xx"
+    if status in {425, 429}:
         return "transport_failed"
     return "broker_rejected"
 
@@ -1235,6 +1239,8 @@ class KISBroker:
             except httpx.HTTPStatusError as exc:
                 status = exc.response.status_code if exc.response is not None else None
                 raise BrokerBalanceError(_balance_http_error_code(status)) from None
+            except httpx.TimeoutException:
+                raise BrokerBalanceError("timeout") from None
             except httpx.HTTPError:
                 raise BrokerBalanceError("transport_failed") from None
             except (ValueError, TypeError):
@@ -1318,6 +1324,8 @@ class KISBroker:
         except httpx.HTTPStatusError as exc:
             status = exc.response.status_code if exc.response is not None else None
             raise BrokerBalanceError(_balance_http_error_code(status)) from None
+        except httpx.TimeoutException:
+            raise BrokerBalanceError("timeout") from None
         except httpx.HTTPError:
             raise BrokerBalanceError("transport_failed") from None
         except (KeyError, TypeError, ValueError):

trex_core/application/account_snapshot.py

@@ -52,10 +52,11 @@ class AccountSnapshotUnavailable(RuntimeError):
         "read_failed",
     })
 
-    def __init__(self, code: str) -> None:
+    def __init__(self, code: str, *, detail_code: str | None = None) -> None:
         if code not in self._CODES:
             raise ValueError(f"unsupported account snapshot error code: {code}")
         self.code = code
+        self.detail_code = detail_code
         super().__init__(f"account snapshot unavailable ({code})")
 
 
@@ -217,7 +218,9 @@ class AccountSnapshotService:
             return self._broker.get_balance()
         except BrokerBalanceError as exc:
             if exc.code != "transport_failed":
-                raise AccountSnapshotUnavailable("live_read_failed") from None
+                raise AccountSnapshotUnavailable(
+                    "live_read_failed", detail_code=exc.code
+                ) from None
         snapshot = self._load_current()
         age = self._age(snapshot.holdings_captured_at, self._sell_max_age)
         _log.warning(

trex_core/application/balance_health.py

@@ -0,0 +1,139 @@
+"""Broker-balance worker health tracking with bounded backoff."""
+from __future__ import annotations
+
+from dataclasses import dataclass
+from datetime import UTC, datetime, timedelta
+from threading import Lock
+from typing import Callable
+
+
+@dataclass(frozen=True)
+class BalanceWorkerHealth:
+    worker: str
+    last_success_at: datetime | None
+    consecutive_failures: int
+    failure_code: str | None
+    failure_at: datetime | None
+    next_retry_at: datetime | None
+
+    def as_dict(self, *, now: datetime, stale_after_sec: float) -> dict[str, object]:
+        stale = False
+        if self.last_success_at is not None and stale_after_sec >= 0:
+            stale = (now - self.last_success_at).total_seconds() > stale_after_sec
+        state = "ok"
+        if self.last_success_at is None:
+            state = "unavailable"
+        elif self.consecutive_failures > 0:
+            state = "unavailable"
+        elif stale:
+            state = "stale"
+        return {
+            "worker": self.worker,
+            "state": state,
+            "last_success_at": (
+                self.last_success_at.astimezone(UTC).isoformat()
+                if self.last_success_at is not None
+                else None
+            ),
+            "consecutive_failures": self.consecutive_failures,
+            "failure_code": self.failure_code,
+            "failure_at": (
+                self.failure_at.astimezone(UTC).isoformat()
+                if self.failure_at is not None
+                else None
+            ),
+            "next_retry_at": (
+                self.next_retry_at.astimezone(UTC).isoformat()
+                if self.next_retry_at is not None
+                else None
+            ),
+            "stale": stale,
+        }
+
+
+class BalanceHealthTracker:
+    def __init__(
+        self,
+        *,
+        clock: Callable[[], datetime] | None = None,
+        base_backoff_sec: float = 15.0,
+        max_backoff_sec: float = 300.0,
+    ) -> None:
+        self._clock = clock or (lambda: datetime.now(tz=UTC))
+        self._base_backoff_sec = max(1.0, float(base_backoff_sec))
+        self._max_backoff_sec = max(self._base_backoff_sec, float(max_backoff_sec))
+        self._lock = Lock()
+        self._states: dict[str, BalanceWorkerHealth] = {}
+
+    def _now(self) -> datetime:
+        return self._clock()
+
+    def _get(self, worker: str) -> BalanceWorkerHealth:
+        return self._states.get(
+            worker,
+            BalanceWorkerHealth(
+                worker=worker,
+                last_success_at=None,
+                consecutive_failures=0,
+                failure_code=None,
+                failure_at=None,
+                next_retry_at=None,
+            ),
+        )
+
+    def record_success(self, worker: str, *, captured_at: datetime | None = None) -> str | None:
+        with self._lock:
+            prev = self._get(worker)
+            recovered = prev.consecutive_failures > 0
+            now = self._now()
+            self._states[worker] = BalanceWorkerHealth(
+                worker=worker,
+                last_success_at=captured_at or now,
+                consecutive_failures=0,
+                failure_code=None,
+                failure_at=None,
+                next_retry_at=None,
+            )
+        return "recovered" if recovered else None
+
+    def record_failure(self, worker: str, *, code: str) -> tuple[str | None, float]:
+        with self._lock:
+            prev = self._get(worker)
+            now = self._now()
+            failures = prev.consecutive_failures + 1
+            backoff = min(
+                self._base_backoff_sec * (2 ** max(0, failures - 1)),
+                self._max_backoff_sec,
+            )
+            self._states[worker] = BalanceWorkerHealth(
+                worker=worker,
+                last_success_at=prev.last_success_at,
+                consecutive_failures=failures,
+                failure_code=code,
+                failure_at=now,
+                next_retry_at=now + timedelta(seconds=backoff),
+            )
+            lifecycle: str | None = None
+            if prev.consecutive_failures == 0 or prev.failure_code != code:
+                lifecycle = "detected"
+            elif failures in {3, 6, 12}:
+                lifecycle = "ongoing"
+        return lifecycle, backoff
+
+    def ready(self, worker: str) -> tuple[bool, float]:
+        with self._lock:
+            state = self._get(worker)
+            now = self._now()
+            retry_at = state.next_retry_at
+            if retry_at is None:
+                return True, 0.0
+            remain = (retry_at - now).total_seconds()
+            if remain <= 0:
+                return True, 0.0
+            return False, remain
+
+    def status(self, worker: str, *, stale_after_sec: float) -> dict[str, object]:
+        with self._lock:
+            state = self._get(worker)
+            now = self._now()
+        return state.as_dict(now=now, stale_after_sec=stale_after_sec)

trex_core/application/broker_port.py

@@ -20,7 +20,7 @@ class BrokerBalanceError(RuntimeError):
 
     _CODES = frozenset({
         "token_issuance_failed", "authentication_failed", "authorization_failed",
-        "transport_failed", "malformed_response", "broker_rejected",
+        "transport_failed", "timeout", "http_5xx", "malformed_response", "broker_rejected",
         "ownership_mismatch",
     })
 

trex_core/application/execution.py

@@ -30,13 +30,16 @@ from dataclasses import dataclass, replace
 from datetime import UTC, datetime, timedelta
 
 from trex_core.application.alarm_emitter import AlarmEmitter
+from trex_core.application.balance_health import BalanceHealthTracker
 from trex_core.application.broker_port import (
     BalanceItem,
+    BrokerBalanceError,
     BrokerPort,
     CancelOutcome,
     CancelState,
     OrderRequest,
 )
+from trex_core.application.account_snapshot import AccountSnapshotUnavailable
 from trex_core.application.ledger_outbox import LedgerOutbox
 from trex_core.application.ledger_port import LedgerTrade
 from trex_core.application.ledger_skip import publish_ledger_skip_alarm
@@ -139,6 +142,8 @@ class ExecutionService:
         # account snapshot only through this injected reader. Reconciliation
         # remains wired directly to the live broker.
         self._sell_dispatch_balance_reader = balance_reader or broker.get_balance
+        self._balance_health = BalanceHealthTracker(clock=self._clock)
+        self._balance_worker = "execution"
 
     # ------------------------------------------------------------
     def run_once(self) -> ExecutionResult:
@@ -171,7 +176,22 @@ class ExecutionService:
                 # surfaces via reconcile_core_holdings (REQ-062 A). No mirror
                 # fallback by design.
                 if sell_balance is None:
+                    ready, backoff_left = self._balance_health.ready(self._balance_worker)
+                    if not ready:
+                        r.sell_skipped_no_balance += 1
+                        _log.info(
+                            "sell dispatch deferred: broker balance backoff active "
+                            "instance_key=%s worker=%s backoff_left_sec=%.1f",
+                            self._instance_key,
+                            self._balance_worker,
+                            backoff_left,
+                        )
+                        return
+                    try:
                         sell_balance = self._sell_dispatch_balance_map()
+                    except (AccountSnapshotUnavailable, BrokerBalanceError):
+                        r.sell_skipped_no_balance += 1
+                        return
                 bal = sell_balance.get(slot.symbol or "", 0)
                 # dcy-021 / REQ-062 (D4): full sell (slot.qty is None) => broker
                 # balance; partial sell => min(order qty, broker balance). Broker
@@ -420,10 +440,60 @@ class ExecutionService:
 
     def _sell_dispatch_balance_map(self) -> dict:
         """Balance used only to size a not-yet-submitted pending sell."""
-        return {
-            b.symbol: int(b.hldg_qty)
-            for b in self._sell_dispatch_balance_reader()
-        }
+        try:
+            holdings = self._sell_dispatch_balance_reader()
+        except AccountSnapshotUnavailable as exc:
+            code = "stale_snapshot" if exc.code == "expired" else (
+                getattr(exc, "detail_code", None) or exc.code
+            )
+            lifecycle, backoff = self._balance_health.record_failure(
+                self._balance_worker, code=code
+            )
+            if lifecycle is not None:
+                _log.warning(
+                    "broker balance unavailable: lifecycle=%s worker=%s instance_key=%s "
+                    "failure_code=%s consecutive_failures=%d backoff_sec=%.1f",
+                    lifecycle,
+                    self._balance_worker,
+                    self._instance_key,
+                    code,
+                    self._balance_health.status(self._balance_worker, stale_after_sec=600)[
+                        "consecutive_failures"
+                    ],
+                    backoff,
+                )
+            raise
+        except BrokerBalanceError as exc:
+            lifecycle, backoff = self._balance_health.record_failure(
+                self._balance_worker, code=exc.code
+            )
+            if lifecycle is not None:
+                _log.warning(
+                    "broker balance unavailable: lifecycle=%s worker=%s instance_key=%s "
+                    "failure_code=%s consecutive_failures=%d backoff_sec=%.1f",
+                    lifecycle,
+                    self._balance_worker,
+                    self._instance_key,
+                    exc.code,
+                    self._balance_health.status(self._balance_worker, stale_after_sec=600)[
+                        "consecutive_failures"
+                    ],
+                    backoff,
+                )
+            raise
+        lifecycle = self._balance_health.record_success(self._balance_worker)
+        if lifecycle == "recovered":
+            state = self._balance_health.status(self._balance_worker, stale_after_sec=600)
+            _log.info(
+                "broker balance recovered: worker=%s instance_key=%s last_success_at=%s",
+                self._balance_worker,
+                self._instance_key,
+                state["last_success_at"],
+            )
+        return {b.symbol: int(b.hldg_qty) for b in holdings}
+
+    def balance_worker_health(self, *, stale_after_sec: float = 600.0) -> dict[str, object]:
+        return self._balance_health.status(self._balance_worker, stale_after_sec=stale_after_sec)
 
     def _resolve_fill_price(self, fs, slot) -> tuple[float | None, bool]:
         """Resolve the fill price from FillStatus, with limit_price backfill.

trex_core/application/snapshot_scheduler.py

@@ -16,7 +16,8 @@ from datetime import date, datetime, time, timedelta, timezone
 from typing import Callable, Optional
 
 from trex_core.application.alarm_emitter import AlarmEmitter
-from trex_core.application.broker_port import BrokerPort
+from trex_core.application.balance_health import BalanceHealthTracker
+from trex_core.application.broker_port import BrokerBalanceError, BrokerPort
 from trex_core.application.portfolio import (
     BrokerCredentialPayload,
     DegradedReason,
@@ -95,6 +96,7 @@ class SnapshotScheduler:
         # REQ-114: entry gate. True = new entries allowed (default).
         # credential_fetch_enabled=False keeps this always True (no gate).
         self._entry_allowed: bool = True
+        self._balance_health = BalanceHealthTracker(clock=self._clock)
 
     # ---- callable from a daemon thread loop --------------------------------
     def run_forever(self, stop: threading.Event, *, tick_sec: float = 60.0) -> None:
@@ -310,7 +312,10 @@ class SnapshotScheduler:
         self._store.swap(items)
         try:
             # BAT-050 / REQ-103: pass warn_store + slot_repo for C-case durable warning.
-            reconcile_positions(
+            self._run_balance_worker(
+                worker="position_reconciliation",
+                stale_after_sec=24 * 60 * 60,
+                run=lambda: reconcile_positions(
                     store=self._store,
                     broker=self._broker,
                     slot_repo=self._slot_repo,
@@ -318,6 +323,7 @@ class SnapshotScheduler:
                     warn_store=self._warn_store,
                     alarm_emitter=self._alarm_emitter,
                     notification_store=self._notification_store,
+                ),
             )
         except Exception:  # noqa: BLE001
             _log.exception("reconciliation pass failed")
@@ -330,18 +336,79 @@ class SnapshotScheduler:
                 try:
                     from trex_core.application.reconciliation import reconcile_core_holdings
                     # BAT-050 / REQ-103: pass warn_store for B-case durable warning.
-                    reconcile_core_holdings(
+                    self._run_balance_worker(
+                        worker="core_holding_reconciliation",
+                        stale_after_sec=24 * 60 * 60,
+                        run=lambda: reconcile_core_holdings(
                             slot_repo=self._slot_repo, slot_service=self._slot_service,
                             broker=self._broker, instance_key=self._instance_key,
                             alarm_emitter=self._alarm_emitter,  # dcy-033 / REQ-100
                             warn_store=self._warn_store,  # BAT-050 / REQ-103
                             notification_store=self._notification_store,  # req-0007 / ac-0024
+                        ),
                     )
                 except Exception:  # noqa: BLE001
                     _log.exception("core-holding divergence reconcile failed")
         self._last_fired_date = self._clock()
         return True
 
+    def _run_balance_worker(
+        self,
+        *,
+        worker: str,
+        stale_after_sec: float,
+        run: Callable[[], object],
+    ) -> None:
+        ready, backoff_left = self._balance_health.ready(worker)
+        if not ready:
+            _log.info(
+                "broker balance worker deferred: worker=%s instance_key=%s backoff_left_sec=%.1f",
+                worker,
+                self._instance_key,
+                backoff_left,
+            )
+            return
+        try:
+            run()
+        except BrokerBalanceError as exc:
+            lifecycle, backoff = self._balance_health.record_failure(worker, code=exc.code)
+            if lifecycle is not None:
+                state = self._balance_health.status(worker, stale_after_sec=stale_after_sec)
+                _log.warning(
+                    "broker balance unavailable: lifecycle=%s worker=%s instance_key=%s "
+                    "failure_code=%s consecutive_failures=%s backoff_sec=%.1f",
+                    lifecycle,
+                    worker,
+                    self._instance_key,
+                    exc.code,
+                    state["consecutive_failures"],
+                    backoff,
+                )
+            return
+        lifecycle = self._balance_health.record_success(worker)
+        if lifecycle == "recovered":
+            state = self._balance_health.status(worker, stale_after_sec=stale_after_sec)
+            _log.info(
+                "broker balance recovered: worker=%s instance_key=%s last_success_at=%s",
+                worker,
+                self._instance_key,
+                state["last_success_at"],
+            )
+
+    def balance_worker_health(
+        self,
+        *,
+        stale_after_sec: float = 24 * 60 * 60,
+    ) -> dict[str, dict[str, object]]:
+        return {
+            "position_reconciliation": self._balance_health.status(
+                "position_reconciliation", stale_after_sec=stale_after_sec
+            ),
+            "core_holding_reconciliation": self._balance_health.status(
+                "core_holding_reconciliation", stale_after_sec=stale_after_sec
+            ),
+        }
+
     # ---- asset-centric slot reconcile (dcy-020/REQ-058, BAT-028) ----------
     def _reconcile_slots(self, items: list) -> None:
         universe = {