fix: address code review issues in resilience module

3 files changed, 42 insertions, 13 deletions

diff --git a/shared/pyproject.toml b/shared/pyproject.toml
index dcddc84..eb74a11 100644
--- a/shared/pyproject.toml
+++ b/shared/pyproject.toml
@@ -15,7 +15,6 @@ dependencies = [
     "pyyaml>=6.0,<7",
     "aiohttp>=3.9,<4",
     "rich>=13.0,<14",
-    "tenacity>=8.2,<10",
 ]
 
 [project.optional-dependencies]
diff --git a/shared/src/shared/resilience.py b/shared/src/shared/resilience.py
index b18aaf7..ef2a1f6 100644
--- a/shared/src/shared/resilience.py
+++ b/shared/src/shared/resilience.py
@@ -12,8 +12,15 @@ import logging
 import random
 import time
 from contextlib import asynccontextmanager
+from enum import StrEnum
 from typing import Any, Callable
 
+
+class _State(StrEnum):
+    CLOSED = "closed"
+    OPEN = "open"
+    HALF_OPEN = "half_open"
+
 logger = logging.getLogger(__name__)
 
 
@@ -73,17 +80,17 @@ class CircuitBreaker:
     """
 
     def __init__(self, failure_threshold: int = 5, cooldown: float = 60.0) -> None:
-        self.failure_threshold = failure_threshold
-        self.cooldown = cooldown
+        self._failure_threshold = failure_threshold
+        self._cooldown = cooldown
         self._failures = 0
-        self._state = "closed"
+        self._state = _State.CLOSED
         self._opened_at: float = 0.0
 
     async def call(self, func: Callable, *args: Any, **kwargs: Any) -> Any:
         """Execute func through the breaker."""
-        if self._state == "open":
-            if time.monotonic() - self._opened_at >= self.cooldown:
-                self._state = "half_open"
+        if self._state == _State.OPEN:
+            if time.monotonic() - self._opened_at >= self._cooldown:
+                self._state = _State.HALF_OPEN
             else:
                 raise RuntimeError("Circuit breaker is open")
 
@@ -91,15 +98,15 @@ class CircuitBreaker:
             result = await func(*args, **kwargs)
         except Exception:
             self._failures += 1
-            if self._state == "half_open":
-                self._state = "open"
+            if self._state == _State.HALF_OPEN:
+                self._state = _State.OPEN
                 self._opened_at = time.monotonic()
                 logger.error(
                     "Circuit breaker re-opened after half-open probe failure (threshold=%d)",
-                    self.failure_threshold,
+                    self._failure_threshold,
                 )
-            elif self._failures >= self.failure_threshold:
-                self._state = "open"
+            elif self._failures >= self._failure_threshold:
+                self._state = _State.OPEN
                 self._opened_at = time.monotonic()
                 logger.error(
                     "Circuit breaker opened after %d consecutive failures",
@@ -109,7 +116,7 @@ class CircuitBreaker:
 
         # Success: reset
         self._failures = 0
-        self._state = "closed"
+        self._state = _State.CLOSED
         return result
 
 
diff --git a/shared/tests/test_resilience.py b/shared/tests/test_resilience.py
index dde47e1..5ed4ac3 100644
--- a/shared/tests/test_resilience.py
+++ b/shared/tests/test_resilience.py
@@ -136,6 +136,29 @@ async def test_half_open_after_cooldown():
     assert result == "recovered"
 
 
+async def test_half_open_reopens_on_failure():
+    cb = CircuitBreaker(failure_threshold=2, cooldown=0.05)
+
+    async def always_fail():
+        raise ConnectionError("fail")
+
+    # Trip the breaker
+    for _ in range(2):
+        with pytest.raises(ConnectionError):
+            await cb.call(always_fail)
+
+    # Wait for cooldown
+    await asyncio.sleep(0.1)
+
+    # Half-open probe should fail and re-open
+    with pytest.raises(ConnectionError):
+        await cb.call(always_fail)
+
+    # Should be open again (no cooldown wait)
+    with pytest.raises(RuntimeError, match="Circuit breaker is open"):
+        await cb.call(always_fail)
+
+
 # --- async_timeout tests ---