sub2api/backend/internal/service/openai_gateway_chat_completions_test.go

package service

import (
	"bytes"
	"context"
	"errors"
	"io"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
	"time"

	"github.com/Wei-Shaw/sub2api/internal/config"
	"github.com/Wei-Shaw/sub2api/internal/pkg/apicompat"
	"github.com/gin-gonic/gin"
	"github.com/stretchr/testify/require"
	"github.com/tidwall/gjson"
)

type openAIChatFailingWriter struct {
	gin.ResponseWriter
	failAfter int
	writes    int
}

func (w *openAIChatFailingWriter) Write(p []byte) (int, error) {
	if w.writes >= w.failAfter {
		return 0, errors.New("write failed: client disconnected")
	}
	w.writes++
	return w.ResponseWriter.Write(p)
}

type openAIChatStreamReadErrorCloser struct {
	payload []byte
	err     error
	sent    bool
}

func (r *openAIChatStreamReadErrorCloser) Read(p []byte) (int, error) {
	if !r.sent {
		r.sent = true
		return copy(p, r.payload), nil
	}
	return 0, r.err
}

func (r *openAIChatStreamReadErrorCloser) Close() error { return nil }

func TestHandleChatStreamingResponse_ClassifiesHTTP2ReadError(t *testing.T) {
	gin.SetMode(gin.TestMode)

	rec := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(rec)
	c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", nil)
	resp := &http.Response{
		StatusCode: http.StatusOK,
		Header: http.Header{
			"Content-Type": []string{"text/event-stream"},
			"x-request-id": []string{"upstream-rid"},
		},
		Body: &openAIChatStreamReadErrorCloser{
			payload: []byte("data: {\"type\":\"response.output_text.delta\",\"delta\":\"partial\"}\n\n"),
			err:     errors.New("stream error: stream ID 5; INTERNAL_ERROR; received from peer"),
		},
	}
	svc := &OpenAIGatewayService{cfg: &config.Config{}}

	result, err := svc.handleChatStreamingResponse(
		resp,
		c,
		&Account{ID: 1, Name: "openai-oauth", Platform: PlatformOpenAI},
		"gpt-5.6-sol",
		"gpt-5.6-sol",
		"gpt-5.6-sol",
		time.Now(),
		0,
	)

	require.Error(t, err)
	require.NotNil(t, result)
	require.True(t, c.Writer.Written(), "partial output must make replay unsafe")
	code, message, ok := OpenAIUpstreamStreamReadErrorDetails(err)
	require.True(t, ok)
	require.Equal(t, OpenAIUpstreamHTTP2StreamErrorCode, code)
	require.Equal(t, "Upstream HTTP/2 stream failed", message)
	require.NotContains(t, message, "stream ID")
	require.NotContains(t, message, "INTERNAL_ERROR")
}

func TestNormalizeResponsesRequestServiceTier(t *testing.T) {
	t.Parallel()

	req := &apicompat.ResponsesRequest{ServiceTier: " fast "}
	normalizeResponsesRequestServiceTier(req)
	require.Equal(t, "priority", req.ServiceTier)

	req.ServiceTier = "flex"
	normalizeResponsesRequestServiceTier(req)
	require.Equal(t, "flex", req.ServiceTier)

	// OpenAI 官方合法 tier 应被透传保留。
	req.ServiceTier = "auto"
	normalizeResponsesRequestServiceTier(req)
	require.Equal(t, "auto", req.ServiceTier)

	req.ServiceTier = "default"
	normalizeResponsesRequestServiceTier(req)
	require.Equal(t, "default", req.ServiceTier)

	req.ServiceTier = "scale"
	normalizeResponsesRequestServiceTier(req)
	require.Equal(t, "scale", req.ServiceTier)

	// 真未知值仍被剥离。
	req.ServiceTier = "turbo"
	normalizeResponsesRequestServiceTier(req)
	require.Empty(t, req.ServiceTier)
}

func TestNormalizeResponsesBodyServiceTier(t *testing.T) {
	t.Parallel()

	body, tier, err := normalizeResponsesBodyServiceTier([]byte(`{"model":"gpt-5.1","service_tier":"fast"}`))
	require.NoError(t, err)
	require.Equal(t, "priority", tier)
	require.Equal(t, "priority", gjson.GetBytes(body, "service_tier").String())

	body, tier, err = normalizeResponsesBodyServiceTier([]byte(`{"model":"gpt-5.1","service_tier":"flex"}`))
	require.NoError(t, err)
	require.Equal(t, "flex", tier)
	require.Equal(t, "flex", gjson.GetBytes(body, "service_tier").String())

	// OpenAI 官方 tier 直接保留在 body 中（透传上游）。
	body, tier, err = normalizeResponsesBodyServiceTier([]byte(`{"model":"gpt-5.1","service_tier":"auto"}`))
	require.NoError(t, err)
	require.Equal(t, "auto", tier)
	require.Equal(t, "auto", gjson.GetBytes(body, "service_tier").String())

	body, tier, err = normalizeResponsesBodyServiceTier([]byte(`{"model":"gpt-5.1","service_tier":"default"}`))
	require.NoError(t, err)
	require.Equal(t, "default", tier)
	require.Equal(t, "default", gjson.GetBytes(body, "service_tier").String())

	body, tier, err = normalizeResponsesBodyServiceTier([]byte(`{"model":"gpt-5.1","service_tier":"scale"}`))
	require.NoError(t, err)
	require.Equal(t, "scale", tier)
	require.Equal(t, "scale", gjson.GetBytes(body, "service_tier").String())

	body, tier, err = normalizeResponsesBodyServiceTier([]byte(`{"model":"gpt-5.6-sol","service_tier":"ultrafast"}`))
	require.NoError(t, err)
	require.Equal(t, "ultrafast", tier)
	require.Equal(t, "ultrafast", gjson.GetBytes(body, "service_tier").String())

	// 真未知值才会被删除。
	body, tier, err = normalizeResponsesBodyServiceTier([]byte(`{"model":"gpt-5.1","service_tier":"turbo"}`))
	require.NoError(t, err)
	require.Empty(t, tier)
	require.False(t, gjson.GetBytes(body, "service_tier").Exists())
}

func TestForwardAsChatCompletions_UnknownModelWithoutMessagesDispatchKeepsRequestedModel(t *testing.T) {
	gin.SetMode(gin.TestMode)

	rec := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(rec)
	body := []byte(`{"model":"gpt6","messages":[{"role":"user","content":"hello"}],"stream":false}`)
	c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", bytes.NewReader(body))
	c.Request.Header.Set("Content-Type", "application/json")

	upstream := &httpUpstreamRecorder{resp: &http.Response{
		StatusCode: http.StatusBadRequest,
		Header:     http.Header{"Content-Type": []string{"application/json"}, "x-request-id": []string{"rid_chat_unknown_model"}},
		Body:       io.NopCloser(strings.NewReader(`{"error":{"type":"invalid_request_error","message":"model not found"}}`)),
	}}

	svc := &OpenAIGatewayService{
		cfg:          &config.Config{},
		httpUpstream: upstream,
	}
	account := &Account{
		ID:          1,
		Name:        "openai-oauth",
		Platform:    PlatformOpenAI,
		Type:        AccountTypeOAuth,
		Concurrency: 1,
		Credentials: map[string]any{
			"access_token":       "oauth-token",
			"chatgpt_account_id": "chatgpt-acc",
		},
	}

	result, err := svc.ForwardAsChatCompletions(context.Background(), c, account, body, "", "")
	require.Error(t, err)
	require.Nil(t, result)
	require.Equal(t, "gpt6", gjson.GetBytes(upstream.lastBody, "model").String())
	require.NotEqual(t, "gpt-5.4", gjson.GetBytes(upstream.lastBody, "model").String())
	require.Equal(t, http.StatusBadRequest, rec.Code)
}

func TestForwardAsChatCompletions_APIKeyPropagatesPromptCacheKeyInResponsesBody(t *testing.T) {
	gin.SetMode(gin.TestMode)

	rec := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(rec)
	body := []byte(`{"model":"gpt-5.4","messages":[{"role":"user","content":"hello"}],"stream":false}`)
	c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", bytes.NewReader(body))
	c.Request.Header.Set("Content-Type", "application/json")
	c.Set("api_key", &APIKey{ID: 99})

	upstream := &httpUpstreamRecorder{resp: &http.Response{
		StatusCode: http.StatusBadRequest,
		Header:     http.Header{"Content-Type": []string{"application/json"}, "x-request-id": []string{"rid_chat_prompt_cache"}},
		Body:       io.NopCloser(strings.NewReader(`{"error":{"type":"invalid_request_error","message":"stop before response parsing"}}`)),
	}}

	svc := &OpenAIGatewayService{
		cfg:          &config.Config{},
		httpUpstream: upstream,
	}
	account := &Account{
		ID:          2,
		Name:        "openai-compatible",
		Platform:    PlatformOpenAI,
		Type:        AccountTypeAPIKey,
		Concurrency: 1,
		Credentials: map[string]any{
			"api_key": "sk-compatible",
		},
		Extra: map[string]any{
			"openai_responses_supported": true,
		},
	}

	result, err := svc.ForwardAsChatCompletions(context.Background(), c, account, body, "cache-key-123", "gpt-5.4")
	require.Error(t, err)
	require.Nil(t, result)
	require.Equal(t, "cache-key-123", gjson.GetBytes(upstream.lastBody, "prompt_cache_key").String())
	require.Equal(t, "gpt-5.4", gjson.GetBytes(upstream.lastBody, "model").String())
	require.Equal(t, "https://api.openai.com/v1/responses", upstream.lastReq.URL.String())
	require.Equal(t, "Bearer sk-compatible", upstream.lastReq.Header.Get("Authorization"))
	require.Equal(t, generateSessionUUID(isolateOpenAISessionID(99, "cache-key-123")), upstream.lastReq.Header.Get("session_id"))
}

func TestForwardAsChatCompletions_APIKeyAutoDerivesStableIsolatedPromptCacheKey(t *testing.T) {
	gin.SetMode(gin.TestMode)

	response := func() *http.Response {
		return &http.Response{
			StatusCode: http.StatusBadRequest,
			Header:     http.Header{"Content-Type": []string{"application/json"}},
			Body:       io.NopCloser(strings.NewReader(`{"error":{"type":"invalid_request_error","message":"stop before response parsing"}}`)),
		}
	}
	upstream := &httpUpstreamRecorder{responses: []*http.Response{response(), response(), response()}}
	svc := &OpenAIGatewayService{cfg: &config.Config{}, httpUpstream: upstream}
	account := &Account{
		ID: 2, Name: "openai-compatible", Platform: PlatformOpenAI, Type: AccountTypeAPIKey, Concurrency: 1,
		Credentials: map[string]any{"api_key": "sk-compatible"},
		Extra:       map[string]any{"openai_responses_supported": true},
	}
	firstBody := []byte(`{"model":"gpt-5.4","messages":[{"role":"system","content":"be concise"},{"role":"user","content":"hello"}],"stream":false}`)
	appendedBody := []byte(`{"model":"gpt-5.4","messages":[{"role":"system","content":"be concise"},{"role":"user","content":"hello"},{"role":"assistant","content":"hi"},{"role":"user","content":"continue"}],"stream":false}`)

	forward := func(apiKeyID int64, body []byte) {
		rec := httptest.NewRecorder()
		c, _ := gin.CreateTestContext(rec)
		c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", bytes.NewReader(body))
		c.Request.Header.Set("Content-Type", "application/json")
		c.Set("api_key", &APIKey{ID: apiKeyID})
		result, err := svc.ForwardAsChatCompletions(context.Background(), c, account, body, "", "gpt-5.4")
		require.Error(t, err)
		require.Nil(t, result)
	}

	forward(99, firstBody)
	forward(99, appendedBody)
	forward(100, appendedBody)

	firstKey := gjson.GetBytes(upstream.bodies[0], "prompt_cache_key").String()
	appendedKey := gjson.GetBytes(upstream.bodies[1], "prompt_cache_key").String()
	otherTenantKey := gjson.GetBytes(upstream.bodies[2], "prompt_cache_key").String()
	require.NotEmpty(t, firstKey)
	require.Equal(t, firstKey, appendedKey)
	require.NotEqual(t, firstKey, otherTenantKey)
	require.Equal(t, generateSessionUUID(firstKey), upstream.requests[0].Header.Get("session_id"))
	require.Equal(t, upstream.requests[0].Header.Get("session_id"), upstream.requests[1].Header.Get("session_id"))
	require.Equal(t, generateSessionUUID(otherTenantKey), upstream.requests[2].Header.Get("session_id"))
	require.NotEqual(t, upstream.requests[1].Header.Get("session_id"), upstream.requests[2].Header.Get("session_id"))
}

func TestForwardAsChatCompletions_ResponsesShapeDoesNotAutoDerivePromptCacheKey(t *testing.T) {
	gin.SetMode(gin.TestMode)

	response := func() *http.Response {
		return &http.Response{
			StatusCode: http.StatusBadRequest,
			Header:     http.Header{"Content-Type": []string{"application/json"}},
			Body:       io.NopCloser(strings.NewReader(`{"error":{"type":"invalid_request_error","message":"stop before response parsing"}}`)),
		}
	}
	upstream := &httpUpstreamRecorder{responses: []*http.Response{response(), response(), response()}}
	svc := &OpenAIGatewayService{cfg: &config.Config{}, httpUpstream: upstream}
	account := &Account{
		ID: 2, Name: "openai-compatible", Platform: PlatformOpenAI, Type: AccountTypeAPIKey, Concurrency: 1,
		Credentials: map[string]any{"api_key": "sk-compatible"},
		Extra:       map[string]any{"openai_responses_supported": true},
	}
	firstBody := []byte(`{"model":"gpt-5.4","input":[{"role":"user","content":[{"type":"input_text","text":"first unrelated input"}]}],"stream":false}`)
	secondBody := []byte(`{"model":"gpt-5.4","input":[{"role":"user","content":[{"type":"input_text","text":"second unrelated input"}]}],"stream":false}`)

	forward := func(body []byte, promptCacheKey string) {
		rec := httptest.NewRecorder()
		c, _ := gin.CreateTestContext(rec)
		c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", bytes.NewReader(body))
		c.Set("api_key", &APIKey{ID: 99})
		result, err := svc.ForwardAsChatCompletions(context.Background(), c, account, body, promptCacheKey, "gpt-5.4")
		require.Error(t, err)
		require.Nil(t, result)
	}

	forward(firstBody, "")
	forward(secondBody, "")
	forward(secondBody, "explicit-responses-key")

	require.False(t, gjson.GetBytes(upstream.bodies[0], "prompt_cache_key").Exists())
	require.Empty(t, upstream.requests[0].Header.Get("session_id"))
	require.False(t, gjson.GetBytes(upstream.bodies[1], "prompt_cache_key").Exists())
	require.Empty(t, upstream.requests[1].Header.Get("session_id"))
	require.Equal(t, "explicit-responses-key", gjson.GetBytes(upstream.bodies[2], "prompt_cache_key").String())
	require.Equal(t, generateSessionUUID(isolateOpenAISessionID(99, "explicit-responses-key")), upstream.requests[2].Header.Get("session_id"))
}

func TestForwardAsChatCompletions_OAuthDoesNotInjectDefaultInstructions(t *testing.T) {
	gin.SetMode(gin.TestMode)

	rec := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(rec)
	body := []byte(`{"model":"gpt-5.4","messages":[{"role":"user","content":"hello"}],"stream":false}`)
	c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", bytes.NewReader(body))
	c.Request.Header.Set("Content-Type", "application/json")

	upstream := &httpUpstreamRecorder{resp: &http.Response{
		StatusCode: http.StatusBadRequest,
		Header:     http.Header{"Content-Type": []string{"application/json"}, "x-request-id": []string{"rid_chat_no_default_instructions"}},
		Body:       io.NopCloser(strings.NewReader(`{"error":{"type":"invalid_request_error","message":"stop before response parsing"}}`)),
	}}

	svc := &OpenAIGatewayService{
		cfg:          &config.Config{},
		httpUpstream: upstream,
	}
	account := &Account{
		ID:          3,
		Name:        "openai-oauth",
		Platform:    PlatformOpenAI,
		Type:        AccountTypeOAuth,
		Concurrency: 1,
		Credentials: map[string]any{
			"access_token":       "oauth-token",
			"chatgpt_account_id": "chatgpt-acc",
		},
	}

	result, err := svc.ForwardAsChatCompletions(context.Background(), c, account, body, "", "gpt-5.4")
	require.Error(t, err)
	require.Nil(t, result)
	require.NotNil(t, upstream.lastReq)
	require.Equal(t, chatgptCodexURL, upstream.lastReq.URL.String())
	require.True(t, gjson.GetBytes(upstream.lastBody, "instructions").Exists())
	require.Equal(t, "", gjson.GetBytes(upstream.lastBody, "instructions").String())
	require.NotContains(t, string(upstream.lastBody), "Communicate with the user by streaming thinking")
}

func forwardOAuthChatCompletionsForUpstreamBody(t *testing.T, body []byte) []byte {
	t.Helper()

	gin.SetMode(gin.TestMode)
	rec := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(rec)
	c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", bytes.NewReader(body))
	c.Request.Header.Set("Content-Type", "application/json")

	upstream := &httpUpstreamRecorder{resp: &http.Response{
		StatusCode: http.StatusBadRequest,
		Header:     http.Header{"Content-Type": []string{"application/json"}, "x-request-id": []string{"rid_chat_system_promotion"}},
		Body:       io.NopCloser(strings.NewReader(`{"error":{"type":"invalid_request_error","message":"stop before response parsing"}}`)),
	}}
	svc := &OpenAIGatewayService{cfg: &config.Config{}, httpUpstream: upstream}
	account := &Account{
		ID:          4,
		Name:        "openai-oauth",
		Platform:    PlatformOpenAI,
		Type:        AccountTypeOAuth,
		Concurrency: 1,
		Credentials: map[string]any{
			"access_token":       "oauth-token",
			"chatgpt_account_id": "chatgpt-acc",
		},
	}

	result, err := svc.ForwardAsChatCompletions(context.Background(), c, account, body, "", "gpt-5.4")
	require.Error(t, err)
	require.Nil(t, result)
	require.NotEmpty(t, upstream.lastBody)
	return upstream.lastBody
}

func TestForwardAsChatCompletions_OAuthPromotesSystemMessageWithoutDuplication(t *testing.T) {
	const systemPrompt = "Unique system prefix for token accounting."
	body := []byte(`{"model":"gpt-5.4","messages":[{"role":"system","content":"` + systemPrompt + `"},{"role":"user","content":"hello"}],"stream":false}`)

	upstreamBody := forwardOAuthChatCompletionsForUpstreamBody(t, body)

	require.Equal(t, systemPrompt, gjson.GetBytes(upstreamBody, "instructions").String())
	require.Equal(t, int64(1), gjson.GetBytes(upstreamBody, "input.#").Int())
	require.Equal(t, "user", gjson.GetBytes(upstreamBody, "input.0.role").String())
	require.Equal(t, 1, strings.Count(string(upstreamBody), systemPrompt))
}

func TestForwardAsChatCompletions_OAuthJsonObjectKeepsSystemMessageInInput(t *testing.T) {
	const systemPrompt = "Return JSON only."
	body := []byte(`{"model":"gpt-5.4","messages":[{"role":"system","content":"` + systemPrompt + `"},{"role":"user","content":"symbol data"}],"response_format":{"type":" JSON_OBJECT "},"stream":false}`)

	upstreamBody := forwardOAuthChatCompletionsForUpstreamBody(t, body)

	require.Equal(t, systemPrompt, gjson.GetBytes(upstreamBody, "instructions").String())
	require.Equal(t, int64(2), gjson.GetBytes(upstreamBody, "input.#").Int())
	require.Equal(t, "developer", gjson.GetBytes(upstreamBody, "input.0.role").String())
	require.Equal(t, systemPrompt, gjson.GetBytes(upstreamBody, "input.0.content").String())
	require.Equal(t, 2, strings.Count(string(upstreamBody), systemPrompt))
}

func TestForwardAsChatCompletions_OAuthKeepsMixedSystemContentInInput(t *testing.T) {
	const systemPrompt = "Inspect this reference image."
	body := []byte(`{"model":"gpt-5.4","messages":[{"role":"system","content":[{"type":"text","text":"` + systemPrompt + `"},{"type":"image_url","image_url":{"url":"https://example.com/reference.png"}}]},{"role":"user","content":"hello"}],"stream":false}`)

	upstreamBody := forwardOAuthChatCompletionsForUpstreamBody(t, body)

	require.Equal(t, systemPrompt, gjson.GetBytes(upstreamBody, "instructions").String())
	require.Equal(t, int64(2), gjson.GetBytes(upstreamBody, "input.#").Int())
	require.Equal(t, "developer", gjson.GetBytes(upstreamBody, "input.0.role").String())
	require.Equal(t, int64(2), gjson.GetBytes(upstreamBody, "input.0.content.#").Int())
	require.Equal(t, "input_image", gjson.GetBytes(upstreamBody, "input.0.content.1.type").String())
	require.Equal(t, "https://example.com/reference.png", gjson.GetBytes(upstreamBody, "input.0.content.1.image_url").String())
}

func TestForwardAsChatCompletions_ClientDisconnectDrainsUpstreamUsage(t *testing.T) {
	gin.SetMode(gin.TestMode)

	rec := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(rec)
	c.Writer = &openAIChatFailingWriter{ResponseWriter: c.Writer, failAfter: 0}
	body := []byte(`{"model":"gpt-5.4","messages":[{"role":"user","content":"hello"}],"stream":true}`)
	c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", bytes.NewReader(body))
	c.Request.Header.Set("Content-Type", "application/json")

	upstreamBody := strings.Join([]string{
		`data: {"type":"response.created","response":{"id":"resp_1","model":"gpt-5.4","status":"in_progress","output":[]}}`,
		"",
		`data: {"type":"response.output_text.delta","delta":"ok"}`,
		"",
		`data: {"type":"response.completed","response":{"id":"resp_1","object":"response","model":"gpt-5.4","status":"completed","output":[{"type":"message","id":"msg_1","role":"assistant","status":"completed","content":[{"type":"output_text","text":"ok"}]}],"usage":{"input_tokens":11,"output_tokens":5,"total_tokens":16,"input_tokens_details":{"cached_tokens":4}}}}`,
		"",
		"data: [DONE]",
		"",
	}, "\n")
	upstream := &httpUpstreamRecorder{resp: &http.Response{
		StatusCode: http.StatusOK,
		Header:     http.Header{"Content-Type": []string{"text/event-stream"}, "x-request-id": []string{"rid_chat_disconnect"}},
		Body:       io.NopCloser(strings.NewReader(upstreamBody)),
	}}

	svc := &OpenAIGatewayService{httpUpstream: upstream}
	account := &Account{
		ID:          1,
		Name:        "openai-oauth",
		Platform:    PlatformOpenAI,
		Type:        AccountTypeOAuth,
		Concurrency: 1,
		Credentials: map[string]any{
			"access_token":       "oauth-token",
			"chatgpt_account_id": "chatgpt-acc",
		},
	}

	result, err := svc.ForwardAsChatCompletions(context.Background(), c, account, body, "", "gpt-5.1")
	require.NoError(t, err)
	require.NotNil(t, result)
	require.Equal(t, 11, result.Usage.InputTokens)
	require.Equal(t, 5, result.Usage.OutputTokens)
	require.Equal(t, 4, result.Usage.CacheReadInputTokens)
}

func TestForwardAsChatCompletions_BufferedContextWindowResponseFailedReturnsErrorWithoutFailover(t *testing.T) {
	gin.SetMode(gin.TestMode)

	rec := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(rec)
	body := []byte(`{"model":"gpt-5.5","messages":[{"role":"user","content":"large prompt"}],"stream":false}`)
	c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", bytes.NewReader(body))
	c.Request.Header.Set("Content-Type", "application/json")

	upstreamBody := strings.Join([]string{
		`event: response.failed`,
		`data: {"type":"response.failed","response":{"id":"resp_failed","object":"response","model":"gpt-5.5","status":"failed","output":[],"error":{"code":"upstream_error","message":"input exceeds the context window"}}}`,
		"",
	}, "\n")
	upstream := &httpUpstreamRecorder{resp: &http.Response{
		StatusCode: http.StatusOK,
		Header:     http.Header{"Content-Type": []string{"text/event-stream"}, "x-request-id": []string{"rid_chat_failed_buffered"}},
		Body:       io.NopCloser(strings.NewReader(upstreamBody)),
	}}

	svc := &OpenAIGatewayService{httpUpstream: upstream}
	account := &Account{
		ID:          1,
		Name:        "openai-oauth",
		Platform:    PlatformOpenAI,
		Type:        AccountTypeOAuth,
		Concurrency: 1,
		Credentials: map[string]any{
			"access_token":       "oauth-token",
			"chatgpt_account_id": "chatgpt-acc",
		},
	}

	result, err := svc.ForwardAsChatCompletions(context.Background(), c, account, body, "", "gpt-5.5")
	require.Error(t, err)
	require.Nil(t, result)
	var failoverErr *UpstreamFailoverError
	require.False(t, errors.As(err, &failoverErr))
	require.True(t, c.Writer.Written())
	require.Equal(t, http.StatusBadGateway, rec.Code)
	require.Contains(t, rec.Body.String(), "input exceeds the context window")
}

func TestForwardAsChatCompletions_StreamContextWindowResponseFailedReturnsErrorWithoutFailover(t *testing.T) {
	gin.SetMode(gin.TestMode)

	rec := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(rec)
	body := []byte(`{"model":"gpt-5.5","messages":[{"role":"user","content":"` + strings.Repeat("large prompt ", 6000) + `"}],"stream":true}`)
	c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", bytes.NewReader(body))
	c.Request.Header.Set("Content-Type", "application/json")

	upstreamBody := strings.Join([]string{
		`data: {"type":"response.created","response":{"id":"resp_failed","model":"gpt-5.5","status":"in_progress","output":[]}}`,
		"",
		`event: response.failed`,
		`data: {"type":"response.failed","response":{"id":"resp_failed","object":"response","model":"gpt-5.5","status":"failed","output":[],"error":{"code":"upstream_error","message":"input exceeds the context window"}}}`,
		"",
	}, "\n")
	upstream := &httpUpstreamRecorder{resp: &http.Response{
		StatusCode: http.StatusOK,
		Header:     http.Header{"Content-Type": []string{"text/event-stream"}, "x-request-id": []string{"rid_chat_failed_stream"}},
		Body:       io.NopCloser(strings.NewReader(upstreamBody)),
	}}

	svc := &OpenAIGatewayService{httpUpstream: upstream}
	account := &Account{
		ID:          1,
		Name:        "openai-oauth",
		Platform:    PlatformOpenAI,
		Type:        AccountTypeOAuth,
		Concurrency: 1,
		Credentials: map[string]any{
			"access_token":       "oauth-token",
			"chatgpt_account_id": "chatgpt-acc",
		},
	}

	result, err := svc.ForwardAsChatCompletions(context.Background(), c, account, body, "", "gpt-5.5")
	require.Error(t, err)
	require.NotNil(t, result)
	var failoverErr *UpstreamFailoverError
	require.False(t, errors.As(err, &failoverErr))
	require.True(t, c.Writer.Written())
	require.Equal(t, http.StatusBadGateway, rec.Code)
	require.Contains(t, rec.Header().Get("Content-Type"), "application/json")
	require.Contains(t, rec.Body.String(), "input exceeds the context window")
	require.NotContains(t, rec.Body.String(), "[DONE]")
}

func TestForwardAsChatCompletions_StreamBareErrorAfterOutputDoesNotFailOver(t *testing.T) {
	gin.SetMode(gin.TestMode)

	rec := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(rec)
	body := []byte(`{"model":"gpt-5.5","messages":[{"role":"user","content":"hello"}],"stream":true}`)
	c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", bytes.NewReader(body))
	c.Request.Header.Set("Content-Type", "application/json")

	upstreamBody := strings.Join([]string{
		`data: {"type":"response.output_text.delta","output_index":0,"content_index":0,"delta":"partial"}`,
		"",
		`event: error`,
		`data: {"type":"error","error":{"type":"server_error","code":"server_error","message":"temporary upstream failure"}}`,
		"",
		`data: [DONE]`,
		"",
	}, "\n")
	upstream := &httpUpstreamRecorder{resp: &http.Response{
		StatusCode: http.StatusOK,
		Header:     http.Header{"Content-Type": []string{"text/event-stream"}},
		Body:       io.NopCloser(strings.NewReader(upstreamBody)),
	}}
	svc := &OpenAIGatewayService{httpUpstream: upstream}
	account := &Account{
		ID: 1, Name: "openai-oauth", Platform: PlatformOpenAI, Type: AccountTypeOAuth, Concurrency: 1,
		Credentials: map[string]any{"access_token": "oauth-token", "chatgpt_account_id": "chatgpt-acc"},
	}

	result, err := svc.ForwardAsChatCompletions(context.Background(), c, account, body, "", "gpt-5.5")

	require.Error(t, err)
	require.NotNil(t, result)
	var failoverErr *UpstreamFailoverError
	require.False(t, errors.As(err, &failoverErr))
	require.Contains(t, rec.Body.String(), "partial")
	require.Contains(t, rec.Body.String(), "temporary upstream failure")
	require.NotContains(t, rec.Body.String(), "[DONE]")
}

func TestForwardAsChatCompletions_StreamCyberPolicyNoFailover(t *testing.T) {
	gin.SetMode(gin.TestMode)

	rec := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(rec)
	body := []byte(`{"model":"gpt-5.5","messages":[{"role":"user","content":"` + strings.Repeat("large prompt ", 6000) + `"}],"stream":true}`)
	c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", bytes.NewReader(body))
	c.Request.Header.Set("Content-Type", "application/json")

	upstreamBody := strings.Join([]string{
		`data: {"type":"response.created","response":{"id":"resp_cyber","model":"gpt-5.5","status":"in_progress","output":[]}}`,
		"",
		`event: response.failed`,
		`data: {"type":"response.failed","response":{"id":"resp_cyber","object":"response","model":"gpt-5.5","status":"failed","output":[],"error":{"code":"cyber_policy","message":"flagged for cyber policy"}}}`,
		"",
	}, "\n")
	upstream := &httpUpstreamRecorder{resp: &http.Response{
		StatusCode: http.StatusOK,
		Header:     http.Header{"Content-Type": []string{"text/event-stream"}, "x-request-id": []string{"rid_chat_cyber"}},
		Body:       io.NopCloser(strings.NewReader(upstreamBody)),
	}}

	svc := &OpenAIGatewayService{httpUpstream: upstream}
	account := &Account{
		ID:          1,
		Name:        "openai-oauth",
		Platform:    PlatformOpenAI,
		Type:        AccountTypeOAuth,
		Concurrency: 1,
		Credentials: map[string]any{
			"access_token":       "oauth-token",
			"chatgpt_account_id": "chatgpt-acc",
		},
	}

	_, err := svc.ForwardAsChatCompletions(context.Background(), c, account, body, "", "gpt-5.5")
	var failoverErr *UpstreamFailoverError
	require.False(t, errors.As(err, &failoverErr), "cyber must NOT trigger failover")
	require.NotNil(t, GetOpsCyberPolicy(c), "cyber mark must be set")
	respBody := rec.Body.String()
	require.Contains(t, respBody, `"error"`)
	require.Contains(t, respBody, `"cyber_policy"`)
	require.Contains(t, respBody, "data: [DONE]")
}

func TestForwardAsChatCompletions_StreamsUsageWithoutClientStreamOptions(t *testing.T) {
	gin.SetMode(gin.TestMode)

	rec := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(rec)
	body := []byte(`{"model":"gpt-5.4","messages":[{"role":"user","content":"hello"}],"stream":true}`)
	c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", bytes.NewReader(body))
	c.Request.Header.Set("Content-Type", "application/json")

	upstreamBody := strings.Join([]string{
		`data: {"type":"response.created","response":{"id":"resp_1","model":"gpt-5.4","status":"in_progress","output":[]}}`,
		"",
		`data: {"type":"response.output_text.delta","delta":"ok"}`,
		"",
		`data: {"type":"response.completed","response":{"id":"resp_1","object":"response","model":"gpt-5.4","status":"completed","output":[{"type":"message","id":"msg_1","role":"assistant","status":"completed","content":[{"type":"output_text","text":"ok"}]}],"usage":{"input_tokens":13,"output_tokens":7,"total_tokens":20,"input_tokens_details":{"cached_tokens":5}}}}`,
		"",
		"data: [DONE]",
		"",
	}, "\n")
	upstream := &httpUpstreamRecorder{resp: &http.Response{
		StatusCode: http.StatusOK,
		Header:     http.Header{"Content-Type": []string{"text/event-stream"}, "x-request-id": []string{"rid_chat_usage_no_stream_options"}},
		Body:       io.NopCloser(strings.NewReader(upstreamBody)),
	}}

	svc := &OpenAIGatewayService{httpUpstream: upstream}
	account := &Account{
		ID:          1,
		Name:        "openai-oauth",
		Platform:    PlatformOpenAI,
		Type:        AccountTypeOAuth,
		Concurrency: 1,
		Credentials: map[string]any{
			"access_token":       "oauth-token",
			"chatgpt_account_id": "chatgpt-acc",
		},
	}

	result, err := svc.ForwardAsChatCompletions(context.Background(), c, account, body, "", "gpt-5.1")
	require.NoError(t, err)
	require.NotNil(t, result)
	require.Equal(t, 13, result.Usage.InputTokens)
	require.Equal(t, 7, result.Usage.OutputTokens)
	require.Equal(t, 5, result.Usage.CacheReadInputTokens)

	responseBody := rec.Body.String()
	require.Contains(t, responseBody, `"usage"`)
	require.Contains(t, responseBody, `"prompt_tokens":13`)
	require.Contains(t, responseBody, `"completion_tokens":7`)
	require.Contains(t, responseBody, `"cached_tokens":5`)
}

func TestForwardAsChatCompletions_StreamsTopLevelTerminalUsage(t *testing.T) {
	gin.SetMode(gin.TestMode)

	rec := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(rec)
	body := []byte(`{"model":"gpt-5.4","messages":[{"role":"user","content":"hello"}],"stream":true}`)
	c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", bytes.NewReader(body))
	c.Request.Header.Set("Content-Type", "application/json")

	upstreamBody := strings.Join([]string{
		`data: {"type":"response.created","response":{"id":"resp_top","model":"gpt-5.4","status":"in_progress","output":[]}}`,
		"",
		`data: {"type":"response.output_text.delta","delta":"ok"}`,
		"",
		`data: {"type":"response.completed","response":{"id":"resp_top","object":"response","model":"gpt-5.4","status":"completed","output":[{"type":"message","id":"msg_1","role":"assistant","status":"completed","content":[{"type":"output_text","text":"ok"}]}]},"usage":{"input_tokens":21,"output_tokens":9,"total_tokens":30,"input_tokens_details":{"cached_tokens":4}}}`,
		"",
		"data: [DONE]",
		"",
	}, "\n")
	upstream := &httpUpstreamRecorder{resp: &http.Response{
		StatusCode: http.StatusOK,
		Header:     http.Header{"Content-Type": []string{"text/event-stream"}, "x-request-id": []string{"rid_chat_top_level_usage"}},
		Body:       io.NopCloser(strings.NewReader(upstreamBody)),
	}}

	svc := &OpenAIGatewayService{httpUpstream: upstream}
	account := &Account{
		ID:          1,
		Name:        "openai-oauth",
		Platform:    PlatformOpenAI,
		Type:        AccountTypeOAuth,
		Concurrency: 1,
		Credentials: map[string]any{
			"access_token":       "oauth-token",
			"chatgpt_account_id": "chatgpt-acc",
		},
	}

	result, err := svc.ForwardAsChatCompletions(context.Background(), c, account, body, "", "gpt-5.1")
	require.NoError(t, err)
	require.NotNil(t, result)
	require.Equal(t, 21, result.Usage.InputTokens)
	require.Equal(t, 9, result.Usage.OutputTokens)
	require.Equal(t, 4, result.Usage.CacheReadInputTokens)

	responseBody := rec.Body.String()
	require.Contains(t, responseBody, `"usage"`)
	require.Contains(t, responseBody, `"prompt_tokens":21`)
	require.Contains(t, responseBody, `"completion_tokens":9`)
	require.Contains(t, responseBody, `"cached_tokens":4`)
}

func TestForwardAsChatCompletions_BufferedTopLevelTerminalUsage(t *testing.T) {
	gin.SetMode(gin.TestMode)

	rec := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(rec)
	body := []byte(`{"model":"gpt-5.4","messages":[{"role":"user","content":"hello"}],"stream":false}`)
	c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", bytes.NewReader(body))
	c.Request.Header.Set("Content-Type", "application/json")

	upstreamBody := strings.Join([]string{
		`data: {"type":"response.completed","response":{"id":"resp_top_buffered","object":"response","model":"gpt-5.4","status":"completed","output":[{"type":"message","id":"msg_1","role":"assistant","status":"completed","content":[{"type":"output_text","text":"ok"}]}]},"usage":{"input_tokens":18,"output_tokens":6,"total_tokens":24,"input_tokens_details":{"cached_tokens":3}}}`,
		"",
		"data: [DONE]",
		"",
	}, "\n")
	upstream := &httpUpstreamRecorder{resp: &http.Response{
		StatusCode: http.StatusOK,
		Header:     http.Header{"Content-Type": []string{"text/event-stream"}, "x-request-id": []string{"rid_chat_buffered_top_level_usage"}},
		Body:       io.NopCloser(strings.NewReader(upstreamBody)),
	}}

	svc := &OpenAIGatewayService{httpUpstream: upstream}
	account := &Account{
		ID:          1,
		Name:        "openai-oauth",
		Platform:    PlatformOpenAI,
		Type:        AccountTypeOAuth,
		Concurrency: 1,
		Credentials: map[string]any{
			"access_token":       "oauth-token",
			"chatgpt_account_id": "chatgpt-acc",
		},
	}

	result, err := svc.ForwardAsChatCompletions(context.Background(), c, account, body, "", "gpt-5.1")
	require.NoError(t, err)
	require.NotNil(t, result)
	require.Equal(t, 18, result.Usage.InputTokens)
	require.Equal(t, 6, result.Usage.OutputTokens)
	require.Equal(t, 3, result.Usage.CacheReadInputTokens)

	responseBody := rec.Body.String()
	require.Contains(t, responseBody, `"usage"`)
	require.Contains(t, responseBody, `"prompt_tokens":18`)
	require.Contains(t, responseBody, `"completion_tokens":6`)
	require.Contains(t, responseBody, `"cached_tokens":3`)
}

func TestForwardAsChatCompletions_TerminalUsageWithoutUpstreamCloseReturns(t *testing.T) {
	gin.SetMode(gin.TestMode)

	rec := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(rec)
	c.Writer = &openAIChatFailingWriter{ResponseWriter: c.Writer, failAfter: 0}
	body := []byte(`{"model":"gpt-5.4","messages":[{"role":"user","content":"hello"}],"stream":true}`)
	c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", bytes.NewReader(body))
	c.Request.Header.Set("Content-Type", "application/json")

	upstreamBody := []byte(`data: {"type":"response.completed","response":{"id":"resp_1","object":"response","model":"gpt-5.4","status":"completed","output":[{"type":"message","id":"msg_1","role":"assistant","status":"completed","content":[{"type":"output_text","text":"ok"}]}],"usage":{"input_tokens":17,"output_tokens":8,"total_tokens":25,"input_tokens_details":{"cached_tokens":6}}}}` + "\n\n")
	upstreamStream := newOpenAICompatBlockingReadCloser(upstreamBody)
	defer func() {
		require.NoError(t, upstreamStream.Close())
	}()
	upstream := &httpUpstreamRecorder{resp: &http.Response{
		StatusCode: http.StatusOK,
		Header:     http.Header{"Content-Type": []string{"text/event-stream"}, "x-request-id": []string{"rid_chat_terminal_no_close"}},
		Body:       upstreamStream,
	}}

	svc := &OpenAIGatewayService{httpUpstream: upstream}
	account := &Account{
		ID:          1,
		Name:        "openai-oauth",
		Platform:    PlatformOpenAI,
		Type:        AccountTypeOAuth,
		Concurrency: 1,
		Credentials: map[string]any{
			"access_token":       "oauth-token",
			"chatgpt_account_id": "chatgpt-acc",
		},
	}

	type forwardResult struct {
		result *OpenAIForwardResult
		err    error
	}
	resultCh := make(chan forwardResult, 1)
	go func() {
		result, err := svc.ForwardAsChatCompletions(context.Background(), c, account, body, "", "gpt-5.1")
		resultCh <- forwardResult{result: result, err: err}
	}()

	select {
	case got := <-resultCh:
		require.NoError(t, got.err)
		require.NotNil(t, got.result)
		require.Equal(t, 17, got.result.Usage.InputTokens)
		require.Equal(t, 8, got.result.Usage.OutputTokens)
		require.Equal(t, 6, got.result.Usage.CacheReadInputTokens)
	case <-time.After(time.Second):
		require.Fail(t, "ForwardAsChatCompletions should return after terminal usage event even if upstream keeps the connection open")
	}
}

func TestForwardAsChatCompletions_EventNamedTerminalWithoutUpstreamCloseReturns(t *testing.T) {
	gin.SetMode(gin.TestMode)

	rec := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(rec)
	body := []byte(`{"model":"gpt-5.4","messages":[{"role":"user","content":"hello"}],"stream":true}`)
	c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", bytes.NewReader(body))
	c.Request.Header.Set("Content-Type", "application/json")

	upstreamBody := []byte(strings.Join([]string{
		`event: response.created`,
		`data: {"response":{"id":"resp_1","model":"gpt-5.4","status":"in_progress","output":[]}}`,
		``,
		`event: response.output_text.delta`,
		`data: {"delta":"ok"}`,
		``,
		`event: response.completed`,
		`data: {"response":{"id":"resp_1","object":"response","model":"gpt-5.4","status":"completed","output":[{"type":"message","id":"msg_1","role":"assistant","status":"completed","content":[{"type":"output_text","text":"ok"}]}],"usage":{"input_tokens":17,"output_tokens":8,"total_tokens":25,"input_tokens_details":{"cached_tokens":6}}}}`,
		``,
		``,
	}, "\n"))
	upstreamStream := newOpenAICompatBlockingReadCloser(upstreamBody)
	defer func() {
		require.NoError(t, upstreamStream.Close())
	}()
	upstream := &httpUpstreamRecorder{resp: &http.Response{
		StatusCode: http.StatusOK,
		Header:     http.Header{"Content-Type": []string{"text/event-stream"}, "x-request-id": []string{"rid_chat_event_named_terminal"}},
		Body:       upstreamStream,
	}}

	svc := &OpenAIGatewayService{httpUpstream: upstream}
	account := &Account{
		ID:          1,
		Name:        "openai-oauth",
		Platform:    PlatformOpenAI,
		Type:        AccountTypeOAuth,
		Concurrency: 1,
		Credentials: map[string]any{
			"access_token":       "oauth-token",
			"chatgpt_account_id": "chatgpt-acc",
		},
	}

	type forwardResult struct {
		result *OpenAIForwardResult
		err    error
	}
	resultCh := make(chan forwardResult, 1)
	go func() {
		result, err := svc.ForwardAsChatCompletions(context.Background(), c, account, body, "", "gpt-5.1")
		resultCh <- forwardResult{result: result, err: err}
	}()

	select {
	case got := <-resultCh:
		require.NoError(t, got.err)
		require.NotNil(t, got.result)
		require.Equal(t, 17, got.result.Usage.InputTokens)
		require.Equal(t, 8, got.result.Usage.OutputTokens)
		require.Equal(t, 6, got.result.Usage.CacheReadInputTokens)
		require.Contains(t, rec.Body.String(), `"content":"ok"`)
	case <-time.After(time.Second):
		require.Fail(t, "ForwardAsChatCompletions should use SSE event names when data payloads omit type")
	}
}

func TestForwardAsChatCompletions_EventTypeDoesNotLeakAcrossFrames(t *testing.T) {
	gin.SetMode(gin.TestMode)

	rec := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(rec)
	body := []byte(`{"model":"gpt-5.4","messages":[{"role":"user","content":"hello"}],"stream":true}`)
	c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", bytes.NewReader(body))
	c.Request.Header.Set("Content-Type", "application/json")

	upstreamBody := strings.Join([]string{
		`event: response.created`,
		`data: {"response":{"id":"resp_1","model":"gpt-5.4","status":"in_progress","output":[]}}`,
		``,
		`data: {"type":"response.output_text.delta","delta":"ok"}`,
		``,
		`event: response.completed`,
		`data: {"response":{"id":"resp_1","object":"response","model":"gpt-5.4","status":"completed","output":[{"type":"message","id":"msg_1","role":"assistant","status":"completed","content":[{"type":"output_text","text":"ok"}]}],"usage":{"input_tokens":17,"output_tokens":8,"total_tokens":25,"input_tokens_details":{"cached_tokens":6}}}}`,
		``,
		`data: [DONE]`,
		``,
	}, "\n")
	upstream := &httpUpstreamRecorder{resp: &http.Response{
		StatusCode: http.StatusOK,
		Header:     http.Header{"Content-Type": []string{"text/event-stream"}, "x-request-id": []string{"rid_chat_event_boundary"}},
		Body:       io.NopCloser(strings.NewReader(upstreamBody)),
	}}

	svc := &OpenAIGatewayService{httpUpstream: upstream}
	account := &Account{
		ID:          1,
		Name:        "openai-oauth",
		Platform:    PlatformOpenAI,
		Type:        AccountTypeOAuth,
		Concurrency: 1,
		Credentials: map[string]any{
			"access_token":       "oauth-token",
			"chatgpt_account_id": "chatgpt-acc",
		},
	}

	result, err := svc.ForwardAsChatCompletions(context.Background(), c, account, body, "", "gpt-5.1")
	require.NoError(t, err)
	require.NotNil(t, result)
	require.Contains(t, rec.Body.String(), `"content":"ok"`)
	require.Contains(t, rec.Body.String(), `data: [DONE]`)
}

func TestForwardAsChatCompletions_BufferedTerminalWithoutUpstreamCloseReturns(t *testing.T) {
	gin.SetMode(gin.TestMode)

	rec := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(rec)
	body := []byte(`{"model":"gpt-5.4","messages":[{"role":"user","content":"hello"}],"stream":false}`)
	c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", bytes.NewReader(body))
	c.Request.Header.Set("Content-Type", "application/json")

	upstreamBody := []byte(`data: {"type":"response.completed","response":{"id":"resp_1","object":"response","model":"gpt-5.4","status":"completed","output":[{"type":"message","id":"msg_1","role":"assistant","status":"completed","content":[{"type":"output_text","text":"ok"}]}],"usage":{"input_tokens":17,"output_tokens":8,"total_tokens":25,"input_tokens_details":{"cached_tokens":6}}}}` + "\n\n")
	upstreamStream := newOpenAICompatBlockingReadCloser(upstreamBody)
	defer func() {
		require.NoError(t, upstreamStream.Close())
	}()
	upstream := &httpUpstreamRecorder{resp: &http.Response{
		StatusCode: http.StatusOK,
		Header:     http.Header{"Content-Type": []string{"text/event-stream"}, "x-request-id": []string{"rid_chat_buffered_terminal_no_close"}},
		Body:       upstreamStream,
	}}

	svc := &OpenAIGatewayService{httpUpstream: upstream}
	account := &Account{
		ID:          1,
		Name:        "openai-oauth",
		Platform:    PlatformOpenAI,
		Type:        AccountTypeOAuth,
		Concurrency: 1,
		Credentials: map[string]any{
			"access_token":       "oauth-token",
			"chatgpt_account_id": "chatgpt-acc",
		},
	}

	type forwardResult struct {
		result *OpenAIForwardResult
		err    error
	}
	resultCh := make(chan forwardResult, 1)
	go func() {
		result, err := svc.ForwardAsChatCompletions(context.Background(), c, account, body, "", "gpt-5.1")
		resultCh <- forwardResult{result: result, err: err}
	}()

	select {
	case got := <-resultCh:
		require.NoError(t, got.err)
		require.NotNil(t, got.result)
		require.Equal(t, 17, got.result.Usage.InputTokens)
		require.Equal(t, 8, got.result.Usage.OutputTokens)
		require.Equal(t, 6, got.result.Usage.CacheReadInputTokens)
		require.Contains(t, rec.Body.String(), `"finish_reason":"stop"`)
	case <-time.After(time.Second):
		require.Fail(t, "ForwardAsChatCompletions buffered response should return after terminal usage event even if upstream keeps the connection open")
	}
}

func TestForwardAsChatCompletions_DoneSentinelWithoutTerminalReturnsError(t *testing.T) {
	gin.SetMode(gin.TestMode)

	rec := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(rec)
	body := []byte(`{"model":"gpt-5.4","messages":[{"role":"user","content":"hello"}],"stream":true}`)
	c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", bytes.NewReader(body))
	c.Request.Header.Set("Content-Type", "application/json")

	upstreamBody := "data: [DONE]\n\n"
	upstream := &httpUpstreamRecorder{resp: &http.Response{
		StatusCode: http.StatusOK,
		Header:     http.Header{"Content-Type": []string{"text/event-stream"}, "x-request-id": []string{"rid_chat_missing_terminal"}},
		Body:       io.NopCloser(strings.NewReader(upstreamBody)),
	}}

	svc := &OpenAIGatewayService{httpUpstream: upstream}
	account := &Account{
		ID:          1,
		Name:        "openai-oauth",
		Platform:    PlatformOpenAI,
		Type:        AccountTypeOAuth,
		Concurrency: 1,
		Credentials: map[string]any{
			"access_token":       "oauth-token",
			"chatgpt_account_id": "chatgpt-acc",
		},
	}

	result, err := svc.ForwardAsChatCompletions(context.Background(), c, account, body, "", "gpt-5.1")
	require.Error(t, err)
	require.Contains(t, err.Error(), "missing terminal event")
	require.NotNil(t, result)
	require.Zero(t, result.Usage.InputTokens)
	require.Zero(t, result.Usage.OutputTokens)
}

func TestForwardAsChatCompletions_UpstreamRequestIgnoresClientCancel(t *testing.T) {
	gin.SetMode(gin.TestMode)

	rec := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(rec)
	reqCtx, cancel := context.WithCancel(context.Background())
	body := []byte(`{"model":"gpt-5.4","messages":[{"role":"user","content":"hello"}],"stream":false}`)
	c.Request = httptest.NewRequest(http.MethodPost, "/v1/chat/completions", bytes.NewReader(body)).WithContext(reqCtx)
	c.Request.Header.Set("Content-Type", "application/json")
	cancel()

	upstreamBody := strings.Join([]string{
		`data: {"type":"response.completed","response":{"id":"resp_1","object":"response","model":"gpt-5.4","status":"completed","output":[{"type":"message","id":"msg_1","role":"assistant","status":"completed","content":[{"type":"output_text","text":"ok"}]}],"usage":{"input_tokens":5,"output_tokens":2,"total_tokens":7}}}`,
		"",
		"data: [DONE]",
		"",
	}, "\n")
	upstream := &httpUpstreamRecorder{resp: &http.Response{
		StatusCode: http.StatusOK,
		Header:     http.Header{"Content-Type": []string{"text/event-stream"}, "x-request-id": []string{"rid_chat_ctx"}},
		Body:       io.NopCloser(strings.NewReader(upstreamBody)),
	}}

	svc := &OpenAIGatewayService{httpUpstream: upstream}
	account := &Account{
		ID:          1,
		Name:        "openai-oauth",
		Platform:    PlatformOpenAI,
		Type:        AccountTypeOAuth,
		Concurrency: 1,
		Credentials: map[string]any{
			"access_token":       "oauth-token",
			"chatgpt_account_id": "chatgpt-acc",
		},
	}

	result, err := svc.ForwardAsChatCompletions(reqCtx, c, account, body, "", "gpt-5.1")
	require.NoError(t, err)
	require.NotNil(t, result)
	require.NotNil(t, upstream.lastReq)
	require.NoError(t, upstream.lastReq.Context().Err())
}

// TestBuildChatStreamErrorSSE verifies F4: the error chunk payload follows the
// OpenAI chat streaming error convention so third-party clients stop retrying.
func TestBuildChatStreamErrorSSE(t *testing.T) {
	got := buildChatStreamErrorSSE("cyber_policy", "blocked by policy")
	require.True(t, strings.HasPrefix(got, "data: "), "must be an SSE data frame")
	payload := strings.TrimSuffix(strings.TrimPrefix(got, "data: "), "\n\n")
	require.Equal(t, "invalid_request_error", gjson.Get(payload, "error.type").String())
	require.Equal(t, "cyber_policy", gjson.Get(payload, "error.code").String())
	require.Equal(t, "blocked by policy", gjson.Get(payload, "error.message").String())
}