feat(circuit-breaker): accept any Collection[int] for failure_status_codes

Requiring frozenset[int] made the natural call site
`failure_status_codes={500, 503}` (a set literal) a ty error. Accept
Collection[int] and freeze internally — membership semantics unchanged,
no friction pushed onto callers. Tests now pass a plain set and a list.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: lesnik512

src/httpware/middleware/resilience/circuit_breaker.py

@@ -27,7 +27,7 @@
 import threading
 import time
 import typing
-from collections.abc import Callable
+from collections.abc import Callable, Collection
 
 import httpx2
 
@@ -73,7 +73,7 @@ def __init__(
         failure_threshold: int,
         reset_timeout: float,
         success_threshold: int,
-        failure_status_codes: frozenset[int] | None,
+        failure_status_codes: Collection[int] | None,
         now: Callable[[], float],
     ) -> None:
         if failure_threshold < 1:
@@ -85,8 +85,10 @@ def __init__(
         self._failure_threshold = failure_threshold
         self._reset_timeout = reset_timeout
         self._success_threshold = success_threshold
+        # Accept any Collection (set, frozenset, list, ...) and freeze it so callers
+        # aren't forced to construct a frozenset just to satisfy the type checker.
         self._failure_status_codes = (
-            failure_status_codes if failure_status_codes is not None else _DEFAULT_FAILURE_STATUS_CODES
+            frozenset(failure_status_codes) if failure_status_codes is not None else _DEFAULT_FAILURE_STATUS_CODES
         )
         self._now = now
         self._state = _CircuitState.CLOSED
@@ -198,7 +200,7 @@ def __init__(
         failure_threshold: int = 5,
         reset_timeout: float = 30.0,
         success_threshold: int = 1,
-        failure_status_codes: frozenset[int] | None = None,
+        failure_status_codes: Collection[int] | None = None,
         _now: Callable[[], float] = time.monotonic,
     ) -> None:
         self._state = _CircuitBreakerState(
@@ -262,7 +264,7 @@ def __init__(
         failure_threshold: int = 5,
         reset_timeout: float = 30.0,
         success_threshold: int = 1,
-        failure_status_codes: frozenset[int] | None = None,
+        failure_status_codes: Collection[int] | None = None,
         _now: Callable[[], float] = time.monotonic,
     ) -> None:
         self._state = _CircuitBreakerState(

tests/test_circuit_breaker.py

@@ -168,11 +168,11 @@ def _raise(request: httpx2.Request) -> httpx2.Response:  # noqa: ARG001
 
 
 async def test_custom_failure_status_codes_trips_on_member() -> None:
-    """A status code in a custom failure set trips the breaker."""
+    """A status code in a custom failure set trips the breaker (plain set accepted)."""
     handler = _StatusSequence([503, 503])
     breaker = AsyncCircuitBreaker(
         failure_threshold=2,
-        failure_status_codes=frozenset({503}),
+        failure_status_codes={503},  # a plain set — any Collection[int] is accepted
         _now=_Clock(),
     )
     async with _client(handler, breaker=breaker) as client:
@@ -189,7 +189,7 @@ async def test_custom_failure_status_codes_excludes_other_5xx() -> None:
     handler = _StatusSequence([500, 500, 500, 500])
     breaker = AsyncCircuitBreaker(
         failure_threshold=2,
-        failure_status_codes=frozenset({503}),
+        failure_status_codes=[503],  # a list, too — frozen internally
         _now=_Clock(),
     )
     async with _client(handler, breaker=breaker) as client:

tests/test_circuit_breaker_sync.py

@@ -140,7 +140,7 @@ def _raise(request: httpx2.Request) -> httpx2.Response:  # noqa: ARG001
 
 def test_custom_failure_status_codes_trips_on_member() -> None:
     handler = _StatusSequence([503, 503])
-    breaker = CircuitBreaker(failure_threshold=2, failure_status_codes=frozenset({503}), _now=_Clock())
+    breaker = CircuitBreaker(failure_threshold=2, failure_status_codes={503}, _now=_Clock())  # plain set accepted
     with _client(handler, breaker=breaker) as client:
         for _ in range(2):
             with pytest.raises(ServiceUnavailableError):
@@ -152,7 +152,7 @@ def test_custom_failure_status_codes_trips_on_member() -> None:
 
 def test_custom_failure_status_codes_excludes_other_5xx() -> None:
     handler = _StatusSequence([500, 500, 500, 500])
-    breaker = CircuitBreaker(failure_threshold=2, failure_status_codes=frozenset({503}), _now=_Clock())
+    breaker = CircuitBreaker(failure_threshold=2, failure_status_codes=[503], _now=_Clock())  # list accepted too
     with _client(handler, breaker=breaker) as client:
         for _ in range(4):
             with pytest.raises(InternalServerError):