diff --git a/packages/agents-a365-observability/src/tracing/constants.ts b/packages/agents-a365-observability/src/tracing/constants.ts
index 162c91a2..3301212d 100644
--- a/packages/agents-a365-observability/src/tracing/constants.ts
+++ b/packages/agents-a365-observability/src/tracing/constants.ts
@@ -102,6 +102,7 @@ export class OpenTelemetryConstants {
   public static readonly GEN_AI_EXECUTION_SOURCE_ID_KEY = 'gen_ai.execution.sourceMetadata.id';
   public static readonly GEN_AI_EXECUTION_SOURCE_NAME_KEY = 'gen_ai.channel.name';
   public static readonly GEN_AI_EXECUTION_SOURCE_DESCRIPTION_KEY = 'gen_ai.channel.link';
+  public static readonly GEN_AI_EXECUTION_SOURCE_SUBCHANNEL_KEY = 'gen_ai.channel.subchannel';
 
   // Custom parent id and parent name key
   public static readonly CUSTOM_PARENT_SPAN_ID_KEY = 'custom.parent.span.id';
diff --git a/packages/agents-a365-observability/src/tracing/contracts.ts b/packages/agents-a365-observability/src/tracing/contracts.ts
index a2db33cd..322dd9ba 100644
--- a/packages/agents-a365-observability/src/tracing/contracts.ts
+++ b/packages/agents-a365-observability/src/tracing/contracts.ts
@@ -64,6 +64,9 @@ export interface SourceMetadata {
 
   /** Optional description providing additional context about the source */
   description?: string;
+
+  /** Optional subchannel identifier */
+  subchannel?: string;
 }
 
 /**
diff --git a/packages/agents-a365-observability/src/tracing/middleware/BaggageBuilder.ts b/packages/agents-a365-observability/src/tracing/middleware/BaggageBuilder.ts
index d7feb434..0d66f6fd 100644
--- a/packages/agents-a365-observability/src/tracing/middleware/BaggageBuilder.ts
+++ b/packages/agents-a365-observability/src/tracing/middleware/BaggageBuilder.ts
@@ -219,6 +219,16 @@ export class BaggageBuilder {
     return this;
   }
 
+  /**
+   * Set the execution source metadata subchannel.
+   * @param value The source metadata subchannel
+   * @returns Self for method chaining
+   */
+  sourceMetadataSubchannel(value: string | null | undefined): BaggageBuilder {
+    this.set(OpenTelemetryConstants.GEN_AI_EXECUTION_SOURCE_SUBCHANNEL_KEY, value);
+    return this;
+  }
+
   /**
    * Set multiple baggage pairs from a dictionary or iterable.
    * @param pairs Dictionary or iterable of key-value pairs
diff --git a/packages/agents-a365-observability/src/tracing/processors/util.ts b/packages/agents-a365-observability/src/tracing/processors/util.ts
index 4b960dae..8d5f33d7 100644
--- a/packages/agents-a365-observability/src/tracing/processors/util.ts
+++ b/packages/agents-a365-observability/src/tracing/processors/util.ts
@@ -47,4 +47,5 @@ export const INVOKE_AGENT_ATTRIBUTES: readonly string[] = [
   consts.GEN_AI_EXECUTION_SOURCE_ID_KEY,
   consts.GEN_AI_EXECUTION_SOURCE_NAME_KEY,
   consts.GEN_AI_EXECUTION_SOURCE_DESCRIPTION_KEY,
+  consts.GEN_AI_EXECUTION_SOURCE_SUBCHANNEL_KEY,
 ];
diff --git a/packages/agents-a365-observability/src/tracing/scopes/InvokeAgentScope.ts b/packages/agents-a365-observability/src/tracing/scopes/InvokeAgentScope.ts
index 0d6b2807..68c43737 100644
--- a/packages/agents-a365-observability/src/tracing/scopes/InvokeAgentScope.ts
+++ b/packages/agents-a365-observability/src/tracing/scopes/InvokeAgentScope.ts
@@ -71,6 +71,7 @@ export class InvokeAgentScope extends OpenTelemetryScope {
         this.setTagMaybe(OpenTelemetryConstants.GEN_AI_EXECUTION_SOURCE_ID_KEY, requestToUse.sourceMetadata.id);
         this.setTagMaybe(OpenTelemetryConstants.GEN_AI_EXECUTION_SOURCE_NAME_KEY, requestToUse.sourceMetadata.name);
         this.setTagMaybe(OpenTelemetryConstants.GEN_AI_EXECUTION_SOURCE_DESCRIPTION_KEY, requestToUse.sourceMetadata.description);
+        this.setTagMaybe(OpenTelemetryConstants.GEN_AI_EXECUTION_SOURCE_SUBCHANNEL_KEY, requestToUse.sourceMetadata.subchannel);
       }
     }
 
diff --git a/packages/agents-a365-observability/src/tracing/scopes/OpenTelemetryScope.ts b/packages/agents-a365-observability/src/tracing/scopes/OpenTelemetryScope.ts
index 71370153..44f0abc2 100644
--- a/packages/agents-a365-observability/src/tracing/scopes/OpenTelemetryScope.ts
+++ b/packages/agents-a365-observability/src/tracing/scopes/OpenTelemetryScope.ts
@@ -169,5 +169,4 @@ export abstract class OpenTelemetryScope implements Disposable {
   public dispose(): void {
     this[Symbol.dispose]();
   }
-
 }
diff --git a/tests/observability/core/BaggageBuilder.test.ts b/tests/observability/core/BaggageBuilder.test.ts
index e3afd04a..e90ecde4 100644
--- a/tests/observability/core/BaggageBuilder.test.ts
+++ b/tests/observability/core/BaggageBuilder.test.ts
@@ -154,6 +154,16 @@ describe('BaggageBuilder', () => {
     });
   });
 
+  describe('metadata support', () => {
+    it('should set source metadata subchannel', () => {
+      const scope = new BaggageBuilder()
+        .sourceMetadataSubchannel('sub-A')
+        .build();
+      const bag = propagation.getBaggage((scope as any).contextWithBaggage);
+      expect(bag?.getEntry(OpenTelemetryConstants.GEN_AI_EXECUTION_SOURCE_SUBCHANNEL_KEY)?.value).toBe('sub-A');
+    });
+  });
+
 });
 
 describe('BaggageScope', () => {
diff --git a/tests/observability/core/scopes.test.ts b/tests/observability/core/scopes.test.ts
index f99ce01d..d9ee7296 100644
--- a/tests/observability/core/scopes.test.ts
+++ b/tests/observability/core/scopes.test.ts
@@ -122,6 +122,25 @@ describe('Scopes', () => {
       expect(() => scope?.recordError(error)).not.toThrow();
       scope?.dispose();
     });
+
+    it('should accept sourceMetadata attributes without error', () => {
+      const invokeAgentDetails: InvokeAgentDetails = {
+        agentId: 'test-agent',
+        request: {
+          content: 'hello',
+          sourceMetadata: {
+            id: 'chan-123',
+            name: 'RootChannel',
+            description: 'Primary channel',
+            subchannel: 'thread-7'
+          }
+        }
+      };
+      expect(() => {
+        const scope = InvokeAgentScope.start(invokeAgentDetails, testTenantDetails);
+        scope?.dispose();
+      }).not.toThrow();
+    });
   });
 
   describe('ExecuteToolScope', () => {