Don't trip the AI circuit breaker on load shedding

With many simultaneous games, AI turns start in bursts and exceed the
in-flight cap. That was counted as an AI failure, so after 5 bursts the
breaker paused the AI for 30 s and every AI seat played random moves.

- Only real failures (timeouts, lost connection, malformed/illegal
  answers, unexpected errors) count towards the breaker; the in-flight
  cap and "overloaded"/"expired" answers from the AI service do not
- AI_MAX_INFLIGHT default 32 -> 64 (>= MAX_ACTIVE_GAMES, matches the AI
  service's AI_MAX_QUEUE)
- Test that load shedding keeps the breaker closed

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

wizard_server/tests/test_limits.py

@@ -200,6 +200,40 @@ def test_ai_circuit_breaker():
     asyncio.run(scenario())
 
 
+class OverloadedAIWebSocket:
+    """Answers every request immediately with the given error message."""
+
+    def __init__(self, bridge_connection_ref, message):
+        self.ref, self.message, self.sent = bridge_connection_ref, message, []
+
+    async def send_json(self, request):
+        self.sent.append(request)
+        future = self.ref[0].pending[request["request_id"]]
+        future.set_result({"type": "error", "request_id": request["request_id"], "message": self.message})
+
+
+def test_load_shedding_does_not_trip_the_breaker():
+    async def scenario():
+        bridge = AIBridge(timeout=1, rng=random.Random(0), breaker_failures=2)
+        ref = []
+        ws = OverloadedAIWebSocket(ref, "overloaded")
+        connection = AIConnection(ws, "fake")
+        ref.append(connection)
+        bridge._connections.append(connection)
+        obs = observation()
+        for _ in range(5):
+            assert await bridge.decide(obs) in obs.legal_actions
+        assert len(ws.sent) == 5  # still asked every time
+        assert bridge.stats()["paused"] is False
+
+        ws.message = "model crashed"  # a real failure counts
+        for _ in range(3):
+            await bridge.decide(obs)
+        assert len(ws.sent) == 7 and bridge.stats()["paused"] is True
+
+    asyncio.run(scenario())
+
+
 def test_ai_inflight_limit():
     async def scenario():
         bridge = AIBridge(timeout=1, rng=random.Random(0), max_inflight=1)
@@ -208,7 +242,9 @@ def test_ai_inflight_limit():
         connection.pending["busy"] = asyncio.get_running_loop().create_future()
         bridge._connections.append(connection)
         obs = observation()
-        assert await bridge.decide(obs) in obs.legal_actions
+        for _ in range(10):
+            assert await bridge.decide(obs) in obs.legal_actions
         assert ws.sent == []  # not even sent: too many requests already waiting
+        assert bridge.stats()["paused"] is False  # load shedding is not a failure
 
     asyncio.run(scenario())