fix: set appProtocol on agent Service ports for A2A discovery

Set `appProtocol: kgateway.dev/a2a` on the Service port created for
each Agent CR so AgentGateway's A2A plugin can discover agent Services
directly via protocol matching.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Signed-off-by: Simon Zhu <simon.zhu@mongodb.com>

Author: syn-zhu

go/core/internal/controller/translator/agent/adk_api_translator.go

@@ -544,9 +544,10 @@ func (a *adkApiTranslator) buildManifest(
 		Spec: corev1.ServiceSpec{
 			Selector: selectorLabels,
 			Ports: []corev1.ServicePort{{
-				Name:       "http",
-				Port:       dep.Port,
-				TargetPort: intstr.FromInt(int(dep.Port)),
+				Name:        "http",
+				Port:        dep.Port,
+				TargetPort:  intstr.FromInt(int(dep.Port)),
+				AppProtocol: ptr.To("kgateway.dev/a2a"),
 			}},
 			Type: corev1.ServiceTypeClusterIP,
 		},

go/core/internal/controller/translator/agent/testdata/outputs/agent_with_allowed_headers.json

@@ -282,6 +282,7 @@
       "spec": {
         "ports": [
           {
+            "appProtocol": "kgateway.dev/a2a",
             "name": "http",
             "port": 8080,
             "targetPort": 8080

go/core/internal/controller/translator/agent/testdata/outputs/agent_with_code.json

@@ -277,6 +277,7 @@
       "spec": {
         "ports": [
           {
+            "appProtocol": "kgateway.dev/a2a",
             "name": "http",
             "port": 8080,
             "targetPort": 8080

go/core/internal/controller/translator/agent/testdata/outputs/agent_with_context_config.json

@@ -293,6 +293,7 @@
       "spec": {
         "ports": [
           {
+            "appProtocol": "kgateway.dev/a2a",
             "name": "http",
             "port": 8080,
             "targetPort": 8080

go/core/internal/controller/translator/agent/testdata/outputs/agent_with_cross_namespace_tools.json

@@ -288,6 +288,7 @@
       "spec": {
         "ports": [
           {
+            "appProtocol": "kgateway.dev/a2a",
             "name": "http",
             "port": 8080,
             "targetPort": 8080

go/core/internal/controller/translator/agent/testdata/outputs/agent_with_custom_sa.json

@@ -241,6 +241,7 @@
       "spec": {
         "ports": [
           {
+            "appProtocol": "kgateway.dev/a2a",
             "name": "http",
             "port": 8080,
             "targetPort": 8080

go/core/internal/controller/translator/agent/testdata/outputs/agent_with_embedding_provider.json

@@ -298,6 +298,7 @@
       "spec": {
         "ports": [
           {
+            "appProtocol": "kgateway.dev/a2a",
             "name": "http",
             "port": 8080,
             "targetPort": 8080

go/core/internal/controller/translator/agent/testdata/outputs/agent_with_git_skills.json

@@ -318,6 +318,7 @@
       "spec": {
         "ports": [
           {
+            "appProtocol": "kgateway.dev/a2a",
             "name": "http",
             "port": 8080,
             "targetPort": 8080

go/core/internal/controller/translator/agent/testdata/outputs/agent_with_http_toolserver.json

@@ -281,6 +281,7 @@
       "spec": {
         "ports": [
           {
+            "appProtocol": "kgateway.dev/a2a",
             "name": "http",
             "port": 8080,
             "targetPort": 8080

go/core/internal/controller/translator/agent/testdata/outputs/agent_with_mcp_service.json

@@ -277,6 +277,7 @@
       "spec": {
         "ports": [
           {
+            "appProtocol": "kgateway.dev/a2a",
             "name": "http",
             "port": 8080,
             "targetPort": 8080