Document callback registry lifecycle risk and add stream() override

T9: Add javadoc to LocalActivityToolCallbackWrapper explaining the leak
risk when workflows are evicted from worker cache mid-execution.

T11: Override stream() in ActivityChatModel to throw
UnsupportedOperationException with a clear message, since streaming
through Temporal activities is not supported.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: donald-pinckney

temporal-spring-ai/src/main/java/io/temporal/springai/model/ActivityChatModel.java

@@ -23,6 +23,7 @@
 import org.springframework.core.io.ByteArrayResource;
 import org.springframework.util.CollectionUtils;
 import org.springframework.util.MimeType;
+import reactor.core.publisher.Flux;
 
 /**
  * A {@link ChatModel} implementation that delegates to a Temporal activity.
@@ -169,6 +170,19 @@ public String getModelName() {
     return modelName;
   }
 
+  /**
+   * Streaming is not supported through Temporal activities.
+   *
+   * @throws UnsupportedOperationException always
+   */
+  @Override
+  public Flux<ChatResponse> stream(Prompt prompt) {
+    throw new UnsupportedOperationException(
+        "Streaming is not supported in ActivityChatModel. "
+            + "Temporal activities are request/response based and cannot stream partial results. "
+            + "Use call() instead.");
+  }
+
   @Override
   public ChatOptions getDefaultOptions() {
     return ToolCallingChatOptions.builder().build();

temporal-spring-ai/src/main/java/io/temporal/springai/tool/LocalActivityToolCallbackWrapper.java

@@ -23,7 +23,12 @@
  * and executes it.
  *
  * <p><b>Memory Management:</b> Callbacks are automatically removed from the map after execution to
- * prevent memory leaks.
+ * prevent memory leaks. However, if a workflow is evicted from the worker's cache mid-execution
+ * (between registering a callback and the {@code finally} block that removes it), the callback
+ * reference will leak until the worker is restarted. This is bounded by the number of concurrent
+ * in-flight tool calls and is unlikely to be a practical issue, but callers should be aware that
+ * the registry size ({@link #getRegisteredCallbackCount()}) may drift above zero under heavy
+ * eviction pressure.
  *
  * <p>This class is primarily used by {@code SandboxingAdvisor} to wrap unsafe tools.
  *