Persist first deployment name in AZURE_AI_MODEL_DEPLOYMENT_NAME

cli/azd/extensions/azure.ai.agents/internal/cmd/init_models.go

@@ -791,7 +791,32 @@ func (a *InitAction) ProcessModels(ctx context.Context, manifest *agent_yaml.Age
 		return nil, nil, fmt.Errorf("failed to inject deployment names into manifest: %w", err)
 	}
 
+	setEnv := func(ctx context.Context, key, value string) error {
+		return setEnvValue(ctx, a.azdClient, a.environment.Name, key, value)
+	}
+	if err := persistFirstDeploymentName(ctx, setEnv, deploymentDetails); err != nil {
+		return nil, nil, fmt.Errorf("failed to set AZURE_AI_MODEL_DEPLOYMENT_NAME: %w", err)
+	}
+
 	fmt.Println("Model deployment details processed and injected into agent definition. Deployment details can also be found in the JSON formatted AI_PROJECT_DEPLOYMENTS environment variable.")
 
 	return updatedManifest, deploymentDetails, nil
 }
+
+// envValueSetter writes a single key-value pair to the azd environment.
+type envValueSetter func(ctx context.Context, key, value string) error
+
+// persistFirstDeploymentName persists the first deployment's name as
+// AZURE_AI_MODEL_DEPLOYMENT_NAME so templates and agent code can reference it.
+// It is a no-op when the deployments slice is empty.
+func persistFirstDeploymentName(
+	ctx context.Context,
+	setEnv envValueSetter,
+	deployments []project.Deployment,
+) error {
+	if len(deployments) == 0 {
+		return nil
+	}
+
+	return setEnv(ctx, "AZURE_AI_MODEL_DEPLOYMENT_NAME", deployments[0].Name)
+}

cli/azd/extensions/azure.ai.agents/internal/cmd/init_models_test.go

@@ -4,10 +4,14 @@
 package cmd
 
 import (
+	"azureaiagent/internal/project"
+	"context"
+	"errors"
 	"testing"
 
 	"github.com/azure/azure-dev/cli/azd/pkg/azdext"
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
 func TestResolveNoPromptCapacity(t *testing.T) {
@@ -172,3 +176,89 @@ func TestSkuPriority(t *testing.T) {
 		})
 	}
 }
+
+func TestPersistFirstDeploymentName(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name        string
+		deployments []project.Deployment
+		setEnvErr   error
+		wantCalled  bool
+		wantKey     string
+		wantValue   string
+		wantErr     bool
+	}{
+		{
+			name:        "empty deployments does not call setter",
+			deployments: []project.Deployment{},
+			wantCalled:  false,
+		},
+		{
+			name:        "nil deployments does not call setter",
+			deployments: nil,
+			wantCalled:  false,
+		},
+		{
+			name: "single deployment persists its name",
+			deployments: []project.Deployment{
+				{Name: "gpt-4o"},
+			},
+			wantCalled: true,
+			wantKey:    "AZURE_AI_MODEL_DEPLOYMENT_NAME",
+			wantValue:  "gpt-4o",
+		},
+		{
+			name: "multiple deployments persists first name only",
+			deployments: []project.Deployment{
+				{Name: "gpt-4o"},
+				{Name: "text-embedding-ada-002"},
+			},
+			wantCalled: true,
+			wantKey:    "AZURE_AI_MODEL_DEPLOYMENT_NAME",
+			wantValue:  "gpt-4o",
+		},
+		{
+			name: "setter error is propagated",
+			deployments: []project.Deployment{
+				{Name: "gpt-4o"},
+			},
+			setEnvErr:  errors.New("grpc unavailable"),
+			wantCalled: true,
+			wantKey:    "AZURE_AI_MODEL_DEPLOYMENT_NAME",
+			wantValue:  "gpt-4o",
+			wantErr:    true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			var called bool
+			var gotKey, gotValue string
+
+			setter := func(_ context.Context, key, value string) error {
+				called = true
+				gotKey = key
+				gotValue = value
+				return tt.setEnvErr
+			}
+
+			err := persistFirstDeploymentName(t.Context(), setter, tt.deployments)
+
+			assert.Equal(t, tt.wantCalled, called, "setter call expectation mismatch")
+
+			if tt.wantCalled {
+				assert.Equal(t, tt.wantKey, gotKey)
+				assert.Equal(t, tt.wantValue, gotValue)
+			}
+
+			if tt.wantErr {
+				require.Error(t, err)
+			} else {
+				require.NoError(t, err)
+			}
+		})
+	}
+}