feat(tool): add tool-level circuit breaker to stop offering repeatedly failing tools

agentscope-core/src/main/java/io/agentscope/core/tool/circuitbreaker/InMemoryToolCircuitBreakerStore.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2024-2026 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.agentscope.core.tool.circuitbreaker;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+/**
+ * Default in-process {@link ToolCircuitBreakerStore}, backed by a {@link ConcurrentHashMap}.
+ *
+ * <p>Suitable for single-replica deployments and for tests. State is per JVM: it is lost on restart
+ * and not shared between replicas, so in a multi-replica deployment every replica trips its own
+ * circuit independently. Use a distributed store when that matters.
+ *
+ * <p>Entries are created lazily on first write and removed once a tool is fully healthy again, so
+ * tools that never fail cost nothing.
+ */
+public class InMemoryToolCircuitBreakerStore implements ToolCircuitBreakerStore {
+
+    private final Map<String, ToolCircuitSnapshot> states = new ConcurrentHashMap<>();
+
+    @Override
+    public ToolCircuitSnapshot snapshot(String toolName) {
+        return states.getOrDefault(toolName, ToolCircuitSnapshot.CLOSED);
+    }
+
+    @Override
+    public boolean compareAndSet(
+            String toolName, ToolCircuitSnapshot expected, ToolCircuitSnapshot update) {
+        AtomicBoolean committed = new AtomicBoolean();
+        states.compute(
+                toolName,
+                (name, current) -> {
+                    ToolCircuitSnapshot actual =
+                            current == null ? ToolCircuitSnapshot.CLOSED : current;
+                    if (!actual.equals(expected)) {
+                        return current;
+                    }
+                    committed.set(true);
+                    return ToolCircuitSnapshot.CLOSED.equals(update) ? null : update;
+                });
+        return committed.get();
+    }
+
+    @Override
+    public void reset(String toolName) {
+        states.remove(toolName);
+    }
+}