Align GoChat with Chatwoot frontend contracts

internal/handler/api/v1/captain_assistant_handler_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"net/http"
 	"net/http/httptest"
@@ -292,13 +293,40 @@ func TestCaptainAssistantHandler_PlaygroundV2AppendsCurrentMessageOnce(t *testin
 	assert.Equal(t, "Hello assistant", provider.lastRequest.Messages[1].Content)
 }
 
+func TestCaptainAssistantHandler_PlaygroundV2ProviderErrorReturnsChatwootFallback(t *testing.T) {
+	provider := &captainPlaygroundFakeProvider{err: errors.New("provider unavailable")}
+	router, db := setupCaptainAssistantHandlerTestWithProvider(t, provider)
+	account := seedCaptainAssistantAccount(t, db, "Captain Org")
+	account.FeatureFlags = `{"captain_integration_v2":true}`
+	require.NoError(t, db.Save(account).Error)
+	assistant := &model.CaptainAssistant{AccountID: account.ID, Name: "Fin", Description: "Support", Config: json.RawMessage(`{"model":"gpt-test"}`), Status: model.AssistantStatusActive}
+	require.NoError(t, db.Create(assistant).Error)
+
+	body := map[string]any{"message_content": "Hello assistant"}
+	w := captainAssistantJSONRequest(t, router, http.MethodPost, fmt.Sprintf("/api/v1/accounts/%d/captain/assistants/%d/playground", account.ID, assistant.ID), body)
+	assert.Equal(t, http.StatusOK, w.Code)
+
+	var payload map[string]any
+	require.NoError(t, json.Unmarshal(w.Body.Bytes(), &payload))
+	assert.Equal(t, "conversation_handoff", payload["response"])
+	assert.Equal(t, false, payload["handoff_tool_called"])
+	assert.Contains(t, payload["reasoning"], "Error occurred: llm generation failed: provider unavailable")
+	assert.NotContains(t, payload, "content")
+	assert.NotContains(t, payload, "success")
+	assert.NotContains(t, payload, "data")
+}
+
 type captainPlaygroundFakeProvider struct {
 	content     string
+	err         error
 	lastRequest llm.ChatRequest
 }
 
 func (p *captainPlaygroundFakeProvider) ChatCompletion(ctx context.Context, req llm.ChatRequest) (*llm.ChatResponse, error) {
 	p.lastRequest = req
+	if p.err != nil {
+		return nil, p.err
+	}
 	return &llm.ChatResponse{Choices: []llm.ChatChoice{{Message: llm.ChatMessage{Role: "assistant", Content: p.content}}}}, nil
 }