fix(ai-proxy): add ids for Vertex tool calls (#3990)

Signed-off-by: DENG <33118163+XinhhD@users.noreply.github.com>
Co-authored-by: woody <yaodiwu618@gmail.com>

plugins/wasm-go/extensions/ai-proxy/provider/vertex_test.go

@@ -2,6 +2,7 @@ package provider
 
 import (
 	"net/http"
+	"strings"
 	"testing"
 
 	"github.com/alibaba/higress/plugins/wasm-go/extensions/ai-proxy/util"
@@ -609,6 +610,8 @@ func TestVertexProviderPreservesFunctionCallThoughtSignature(t *testing.T) {
 	require.Len(t, response.Choices, 1)
 	require.NotNil(t, response.Choices[0].Message)
 	require.Len(t, response.Choices[0].Message.ToolCalls, 1)
+	assert.NotEmpty(t, response.Choices[0].Message.ToolCalls[0].Id)
+	assert.True(t, strings.HasPrefix(response.Choices[0].Message.ToolCalls[0].Id, "call_"))
 	assert.Equal(t, "thought-signature-from-vertex", response.Choices[0].Message.ToolCalls[0].ThoughtSignature)
 	assert.Equal(
 		t,
@@ -617,6 +620,48 @@ func TestVertexProviderPreservesFunctionCallThoughtSignature(t *testing.T) {
 	)
 }
 
+func TestVertexProviderStreamToolCallIncludesStableID(t *testing.T) {
+	v := &vertexProvider{}
+	ctx := newMockMultipartHttpContext()
+	ctx.SetContext(ctxKeyFinalRequestModel, "gemini-3.1-pro-preview")
+	vertexResp := &vertexChatResponse{
+		ResponseId: "vertex-response-id",
+		Candidates: []vertexChatCandidate{
+			{
+				Index: 0,
+				Content: vertexChatContent{
+					Role: "model",
+					Parts: []vertexPart{
+						{
+							FunctionCall: &vertexFunctionCall{
+								Name: "lookup",
+								Args: map[string]interface{}{"query": "test"},
+							},
+							ThoughtSignature: "thought-signature-from-vertex",
+						},
+					},
+				},
+				FinishReason: "STOP",
+			},
+		},
+	}
+
+	first := v.buildChatCompletionStreamResponse(ctx, vertexResp)
+	second := v.buildChatCompletionStreamResponse(ctx, vertexResp)
+
+	require.Len(t, first.Choices, 1)
+	require.NotNil(t, first.Choices[0].Delta)
+	require.Len(t, first.Choices[0].Delta.ToolCalls, 1)
+	firstID := first.Choices[0].Delta.ToolCalls[0].Id
+	assert.NotEmpty(t, firstID)
+	assert.True(t, strings.HasPrefix(firstID, "call_"))
+
+	require.Len(t, second.Choices, 1)
+	require.NotNil(t, second.Choices[0].Delta)
+	require.Len(t, second.Choices[0].Delta.ToolCalls, 1)
+	assert.Equal(t, firstID, second.Choices[0].Delta.ToolCalls[0].Id)
+}
+
 func TestVertexProviderRestoresFunctionCallThoughtSignature(t *testing.T) {
 	v := &vertexProvider{}
 	req := &chatCompletionRequest{