Propagate global dd_tags to LLMObs span tags

dd-java-agent/agent-llmobs/src/main/java/datadog/trace/llmobs/domain/DDLLMObsSpan.java

@@ -1,6 +1,7 @@
 package datadog.trace.llmobs.domain;
 
 import datadog.context.ContextScope;
+import datadog.trace.api.Config;
 import datadog.trace.api.DDSpanTypes;
 import datadog.trace.api.DDTraceId;
 import datadog.trace.api.WellKnownTags;
@@ -72,6 +73,11 @@ public DDLLMObsSpan(
 
     span = spanBuilder.start();
 
+    // set global dd_tags as base layer so UST and span-level tags can override them
+    for (Map.Entry<String, String> entry : Config.get().getGlobalTags().entrySet()) {
+      span.setTag(LLMOBS_TAG_PREFIX + entry.getKey(), entry.getValue());
+    }
+
     // set UST (unified service tags, env, service, version)
     span.setTag(ENV, wellKnownTags.getEnv());
     span.setTag(SERVICE, wellKnownTags.getService());

dd-java-agent/agent-llmobs/src/test/groovy/datadog/trace/llmobs/domain/DDLLMObsSpanTest.groovy

@@ -402,6 +402,17 @@ class DDLLMObsSpanTest  extends DDSpecification{
     null          | "has_session_id:0"
   }
 
+  def "global dd_tags are included in LLMObs span tags"() {
+    setup:
+    injectSysConfig("trace.global.tags", "team:backend,owner:ml-platform")
+    def test = llmObsSpan(Tags.LLMOBS_WORKFLOW_SPAN_KIND, "test-span")
+
+    expect:
+    def innerSpan = (AgentSpan) test.span
+    innerSpan.getTag(LLMOBS_TAG_PREFIX + "team") == "backend"
+    innerSpan.getTag(LLMOBS_TAG_PREFIX + "owner") == "ml-platform"
+  }
+
   private LLMObsSpan llmObsSpan(String kind, name) {
     llmObsSpan(kind, name, null)
   }

dd-java-agent/instrumentation/openai-java/openai-java-3.0/src/main/java/datadog/trace/instrumentation/openai_java/OpenAiDecorator.java

@@ -13,6 +13,7 @@
 import datadog.trace.bootstrap.instrumentation.api.UTF8BytesString;
 import datadog.trace.bootstrap.instrumentation.decorator.ClientDecorator;
 import java.util.List;
+import java.util.Map;
 
 public class OpenAiDecorator extends ClientDecorator {
   public static final OpenAiDecorator DECORATE = new OpenAiDecorator();
@@ -91,6 +92,11 @@ protected CharSequence component() {
   @Override
   public AgentSpan afterStart(AgentSpan span) {
     if (llmObsEnabled) {
+      // set global dd_tags as base layer so UST and span-level tags can override them
+      for (Map.Entry<String, String> entry : Config.get().getGlobalTags().entrySet()) {
+        span.setTag(CommonTags.TAG_PREFIX + entry.getKey(), entry.getValue());
+      }
+
       // set UST (unified service tags, env, service, version)
       span.setTag(CommonTags.ENV, wellKnownTags.getEnv());
       span.setTag(CommonTags.SERVICE, wellKnownTags.getService());

dd-java-agent/instrumentation/openai-java/openai-java-3.0/src/test/groovy/GlobalTagsTest.groovy

@@ -0,0 +1,26 @@
+import static datadog.trace.agent.test.utils.TraceUtils.runUnderTrace
+
+/**
+ * Verifies that global tags (dd.trace.global.tags / DD_TAGS) are propagated to LLMObs span tags in the OpenAI instrumentation.
+ */
+class GlobalTagsTest extends OpenAiTest {
+
+  @Override
+  void configurePreAgent() {
+    super.configurePreAgent()
+    injectSysConfig("trace.global.tags", "team:backend,owner:ml-platform")
+  }
+
+  def "global dd_tags are included in OpenAI LLMObs span tags"() {
+    when:
+    runUnderTrace("parent") {
+      openAiClient.chat().completions().create(chatCompletionCreateParams(false))
+    }
+    TEST_WRITER.waitForTraces(1)
+    def openAiSpan = TEST_WRITER.flatten().find { it.operationName.toString() == "openai.request" }
+
+    then:
+    openAiSpan.getTag("_ml_obs_tag.team") == "backend"
+    openAiSpan.getTag("_ml_obs_tag.owner") == "ml-platform"
+  }
+}