From 0e7215abb40ddf8253ae32d640cf47e76055d96b Mon Sep 17 00:00:00 2001
From: mhyeon-lee <mhyeon.lee@gmail.com>
Date: Thu, 29 Jan 2026 23:06:27 +0900
Subject: [PATCH 1/2] fix: merge metadata appendArtifactToTask metadata

---
 .../java/io/a2a/server/tasks/TaskManagerTest.java    |  5 +++++
 spec/src/main/java/io/a2a/util/Utils.java            | 12 ++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/server-common/src/test/java/io/a2a/server/tasks/TaskManagerTest.java b/server-common/src/test/java/io/a2a/server/tasks/TaskManagerTest.java
index f14ebc0fe..b01dda050 100644
--- a/server-common/src/test/java/io/a2a/server/tasks/TaskManagerTest.java
+++ b/server-common/src/test/java/io/a2a/server/tasks/TaskManagerTest.java
@@ -190,6 +190,7 @@ public void testTaskArtifactUpdateEventAppendTrueWithExistingArtifact() throws A
                 .artifactId("artifact-id")
                 .name("artifact-1")
                 .parts(Collections.singletonList(new TextPart("existing content")))
+                .metadata(Map.of("key1", "value1"))
                 .build();
         Task taskWithArtifact = Task.builder(initialTask)
                 .artifacts(Collections.singletonList(existingArtifact))
@@ -201,6 +202,7 @@ public void testTaskArtifactUpdateEventAppendTrueWithExistingArtifact() throws A
                 .artifactId("artifact-id")
                 .name("artifact-1")
                 .parts(Collections.singletonList(new TextPart("new content")))
+                .metadata(Map.of("key2", "value2"))
                 .build();
         TaskArtifactUpdateEvent event = TaskArtifactUpdateEvent.builder()
                 .taskId(minimalTask.id())
@@ -217,6 +219,9 @@ public void testTaskArtifactUpdateEventAppendTrueWithExistingArtifact() throws A
         assertEquals(2, updatedArtifact.parts().size());
         assertEquals("existing content", ((TextPart) updatedArtifact.parts().get(0)).text());
         assertEquals("new content", ((TextPart) updatedArtifact.parts().get(1)).text());
+
+        assertEquals("value1", updatedArtifact.metadata().get("key1"));
+        assertEquals("value2", updatedArtifact.metadata().get("key2"));
     }
 
     @Test
diff --git a/spec/src/main/java/io/a2a/util/Utils.java b/spec/src/main/java/io/a2a/util/Utils.java
index 792365579..c61784205 100644
--- a/spec/src/main/java/io/a2a/util/Utils.java
+++ b/spec/src/main/java/io/a2a/util/Utils.java
@@ -3,7 +3,9 @@
 import static io.a2a.util.Assert.checkNotNullParam;
 
 import java.util.ArrayList;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 import java.util.logging.Logger;
 
 import com.google.gson.Gson;
@@ -129,8 +131,18 @@ public static Task appendArtifactToTask(Task task, TaskArtifactUpdateEvent event
             log.fine(String.format("Appending parts to artifact id %s for task %s", artifactId, taskId));
             List<Part<?>> parts = new ArrayList<>(existingArtifact.parts());
             parts.addAll(newArtifact.parts());
+
+            Map<String, Object> metadata = new HashMap<>();
+            if (existingArtifact.metadata() != null) {
+                metadata.putAll(existingArtifact.metadata());
+            }
+            if (newArtifact.metadata() != null) {
+                metadata.putAll(newArtifact.metadata());
+            }
+
             Artifact updated = Artifact.builder(existingArtifact)
                     .parts(parts)
+                    .metadata(metadata)
                     .build();
             artifacts.set(existingArtifactIndex, updated);
         } else {

From 253d06840b0e7463b2c604624aa6ba6886fd5406 Mon Sep 17 00:00:00 2001
From: mhyeon-lee <mhyeon.lee@gmail.com>
Date: Fri, 6 Feb 2026 12:01:16 +0900
Subject: [PATCH 2/2] Fix mergedMetadata maintain null

---
 spec/src/main/java/io/a2a/util/Utils.java | 17 ++++++++++-------
 1 file changed, 10 insertions(+), 7 deletions(-)

diff --git a/spec/src/main/java/io/a2a/util/Utils.java b/spec/src/main/java/io/a2a/util/Utils.java
index c61784205..44d713f75 100644
--- a/spec/src/main/java/io/a2a/util/Utils.java
+++ b/spec/src/main/java/io/a2a/util/Utils.java
@@ -132,17 +132,20 @@ public static Task appendArtifactToTask(Task task, TaskArtifactUpdateEvent event
             List<Part<?>> parts = new ArrayList<>(existingArtifact.parts());
             parts.addAll(newArtifact.parts());
 
-            Map<String, Object> metadata = new HashMap<>();
-            if (existingArtifact.metadata() != null) {
-                metadata.putAll(existingArtifact.metadata());
-            }
-            if (newArtifact.metadata() != null) {
-                metadata.putAll(newArtifact.metadata());
+            Map<String, Object> mergedMetadata = null;
+            if (existingArtifact.metadata() != null || newArtifact.metadata() != null) {
+                mergedMetadata = new HashMap<>();
+                if (existingArtifact.metadata() != null) {
+                    mergedMetadata.putAll(existingArtifact.metadata());
+                }
+                if (newArtifact.metadata() != null) {
+                    mergedMetadata.putAll(newArtifact.metadata());
+                }
             }
 
             Artifact updated = Artifact.builder(existingArtifact)
                     .parts(parts)
-                    .metadata(metadata)
+                    .metadata(mergedMetadata)
                     .build();
             artifacts.set(existingArtifactIndex, updated);
         } else {