feat(agent): add engine-neutral model-turn journal contract

argi-agent/argi-agent-core/pom.xml

@@ -44,6 +44,10 @@
             <groupId>io.github.agentic-ai-java</groupId>
             <artifactId>argi-runtime-api</artifactId>
         </dependency>
+        <dependency>
+            <groupId>io.github.agentic-ai-java</groupId>
+            <artifactId>argi-runtime-core</artifactId>
+        </dependency>
         <dependency>
             <groupId>com.fasterxml.jackson.core</groupId>
             <artifactId>jackson-databind</artifactId>

argi-agent/argi-agent-core/src/main/java/io/github/agentic/ai/agent/durable/MissingResponsePolicy.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2025-2026 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
+ *
+ *      https://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.github.agentic.ai.agent.durable;
+
+/** Controls whether a model turn with a reserved call but no recorded response may be retried. */
+public enum MissingResponsePolicy {
+
+	/** Stop recovery when the outcome of a reserved model call is unknown. */
+	FAIL_CLOSED,
+
+	/** Permit another model call while the total attempt limit has room. */
+	REASK
+
+}

argi-agent/argi-agent-core/src/main/java/io/github/agentic/ai/agent/durable/ModelTurnAttemptPolicy.java

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2025-2026 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
+ *
+ *      https://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.github.agentic.ai.agent.durable;
+
+import static java.util.Objects.requireNonNull;
+
+/** Immutable recovery policy and total model-call limit for one logical turn. */
+public record ModelTurnAttemptPolicy(MissingResponsePolicy missingResponsePolicy, int maxAttempts) {
+
+	public static final int DEFAULT_MAX_ATTEMPTS = 1;
+
+	/** The default permits the initial call and fails closed on recovery. */
+	public static final ModelTurnAttemptPolicy DEFAULT =
+			new ModelTurnAttemptPolicy(MissingResponsePolicy.FAIL_CLOSED, DEFAULT_MAX_ATTEMPTS);
+
+	public ModelTurnAttemptPolicy {
+		requireNonNull(missingResponsePolicy, "missingResponsePolicy cannot be null");
+		if (maxAttempts < 1) {
+			throw new IllegalArgumentException("maxAttempts must be positive");
+		}
+	}
+
+}