Merge remote-tracking branch 'origin/main' into feat/billing-ledger-decouple-usage-log-20260312

backend/internal/domain/constants.go

@@ -85,6 +85,8 @@ var DefaultAntigravityModelMapping = map[string]string{
 	"claude-haiku-4-5-20251001": "claude-sonnet-4-5",
 	// Gemini 2.5 白名单
 	"gemini-2.5-flash":               "gemini-2.5-flash",
+	"gemini-2.5-flash-image":         "gemini-2.5-flash-image",
+	"gemini-2.5-flash-image-preview": "gemini-2.5-flash-image",
 	"gemini-2.5-flash-lite":          "gemini-2.5-flash-lite",
 	"gemini-2.5-flash-thinking":      "gemini-2.5-flash-thinking",
 	"gemini-2.5-pro":                 "gemini-2.5-pro",

backend/internal/domain/constants_test.go

@@ -6,6 +6,8 @@ func TestDefaultAntigravityModelMapping_ImageCompatibilityAliases(t *testing.T)
 	t.Parallel()
 
 	cases := map[string]string{
+		"gemini-2.5-flash-image":         "gemini-2.5-flash-image",
+		"gemini-2.5-flash-image-preview": "gemini-2.5-flash-image",
 		"gemini-3.1-flash-image":         "gemini-3.1-flash-image",
 		"gemini-3.1-flash-image-preview": "gemini-3.1-flash-image",
 		"gemini-3-pro-image":             "gemini-3.1-flash-image",

backend/internal/handler/admin/account_handler.go

@@ -628,6 +628,7 @@ func (h *AccountHandler) Delete(c *gin.Context) {
 // TestAccountRequest represents the request body for testing an account
 type TestAccountRequest struct {
 	ModelID string `json:"model_id"`
+	Prompt  string `json:"prompt"`
 }
 
 type SyncFromCRSRequest struct {
@@ -658,7 +659,7 @@ func (h *AccountHandler) Test(c *gin.Context) {
 	_ = c.ShouldBindJSON(&req)
 
 	// Use AccountTestService to test the account with SSE streaming
-	if err := h.accountTestService.TestAccountConnection(c, accountID, req.ModelID); err != nil {
+	if err := h.accountTestService.TestAccountConnection(c, accountID, req.ModelID, req.Prompt); err != nil {
 		// Error already sent via SSE, just log
 		return
 	}

backend/internal/handler/admin/dashboard_handler.go

@@ -249,11 +249,12 @@ func (h *DashboardHandler) GetUsageTrend(c *gin.Context) {
 		}
 	}
 
-	trend, err := h.dashboardService.GetUsageTrendWithFilters(c.Request.Context(), startTime, endTime, granularity, userID, apiKeyID, accountID, groupID, model, requestType, stream, billingType)
+	trend, hit, err := h.getUsageTrendCached(c.Request.Context(), startTime, endTime, granularity, userID, apiKeyID, accountID, groupID, model, requestType, stream, billingType)
 	if err != nil {
 		response.Error(c, 500, "Failed to get usage trend")
 		return
 	}
+	c.Header("X-Snapshot-Cache", cacheStatusValue(hit))
 
 	response.Success(c, gin.H{
 		"trend":       trend,
@@ -321,11 +322,12 @@ func (h *DashboardHandler) GetModelStats(c *gin.Context) {
 		}
 	}
 
-	stats, err := h.dashboardService.GetModelStatsWithFilters(c.Request.Context(), startTime, endTime, userID, apiKeyID, accountID, groupID, requestType, stream, billingType)
+	stats, hit, err := h.getModelStatsCached(c.Request.Context(), startTime, endTime, userID, apiKeyID, accountID, groupID, requestType, stream, billingType)
 	if err != nil {
 		response.Error(c, 500, "Failed to get model statistics")
 		return
 	}
+	c.Header("X-Snapshot-Cache", cacheStatusValue(hit))
 
 	response.Success(c, gin.H{
 		"models":     stats,
@@ -391,11 +393,12 @@ func (h *DashboardHandler) GetGroupStats(c *gin.Context) {
 		}
 	}
 
-	stats, err := h.dashboardService.GetGroupStatsWithFilters(c.Request.Context(), startTime, endTime, userID, apiKeyID, accountID, groupID, requestType, stream, billingType)
+	stats, hit, err := h.getGroupStatsCached(c.Request.Context(), startTime, endTime, userID, apiKeyID, accountID, groupID, requestType, stream, billingType)
 	if err != nil {
 		response.Error(c, 500, "Failed to get group statistics")
 		return
 	}
+	c.Header("X-Snapshot-Cache", cacheStatusValue(hit))
 
 	response.Success(c, gin.H{
 		"groups":     stats,
@@ -416,11 +419,12 @@ func (h *DashboardHandler) GetAPIKeyUsageTrend(c *gin.Context) {
 		limit = 5
 	}
 
-	trend, err := h.dashboardService.GetAPIKeyUsageTrend(c.Request.Context(), startTime, endTime, granularity, limit)
+	trend, hit, err := h.getAPIKeyUsageTrendCached(c.Request.Context(), startTime, endTime, granularity, limit)
 	if err != nil {
 		response.Error(c, 500, "Failed to get API key usage trend")
 		return
 	}
+	c.Header("X-Snapshot-Cache", cacheStatusValue(hit))
 
 	response.Success(c, gin.H{
 		"trend":       trend,
@@ -442,11 +446,12 @@ func (h *DashboardHandler) GetUserUsageTrend(c *gin.Context) {
 		limit = 12
 	}
 
-	trend, err := h.dashboardService.GetUserUsageTrend(c.Request.Context(), startTime, endTime, granularity, limit)
+	trend, hit, err := h.getUserUsageTrendCached(c.Request.Context(), startTime, endTime, granularity, limit)
 	if err != nil {
 		response.Error(c, 500, "Failed to get user usage trend")
 		return
 	}
+	c.Header("X-Snapshot-Cache", cacheStatusValue(hit))
 
 	response.Success(c, gin.H{
 		"trend":       trend,

backend/internal/handler/admin/dashboard_handler_cache_test.go

+package admin
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/Wei-Shaw/sub2api/internal/pkg/usagestats"
+	"github.com/Wei-Shaw/sub2api/internal/service"
+	"github.com/gin-gonic/gin"
+	"github.com/stretchr/testify/require"
+)
+
+type dashboardUsageRepoCacheProbe struct {
+	service.UsageLogRepository
+	trendCalls      atomic.Int32
+	usersTrendCalls atomic.Int32
+}
+
+func (r *dashboardUsageRepoCacheProbe) GetUsageTrendWithFilters(
+	ctx context.Context,
+	startTime, endTime time.Time,
+	granularity string,
+	userID, apiKeyID, accountID, groupID int64,
+	model string,
+	requestType *int16,
+	stream *bool,
+	billingType *int8,
+) ([]usagestats.TrendDataPoint, error) {
+	r.trendCalls.Add(1)
+	return []usagestats.TrendDataPoint{{
+		Date:        "2026-03-11",
+		Requests:    1,
+		TotalTokens: 2,
+		Cost:        3,
+		ActualCost:  4,
+	}}, nil
+}
+
+func (r *dashboardUsageRepoCacheProbe) GetUserUsageTrend(
+	ctx context.Context,
+	startTime, endTime time.Time,
+	granularity string,
+	limit int,
+) ([]usagestats.UserUsageTrendPoint, error) {
+	r.usersTrendCalls.Add(1)
+	return []usagestats.UserUsageTrendPoint{{
+		Date:       "2026-03-11",
+		UserID:     1,
+		Email:      "cache@test.dev",
+		Requests:   2,
+		Tokens:     20,
+		Cost:       2,
+		ActualCost: 1,
+	}}, nil
+}
+
+func resetDashboardReadCachesForTest() {
+	dashboardTrendCache = newSnapshotCache(30 * time.Second)
+	dashboardUsersTrendCache = newSnapshotCache(30 * time.Second)
+	dashboardAPIKeysTrendCache = newSnapshotCache(30 * time.Second)
+	dashboardModelStatsCache = newSnapshotCache(30 * time.Second)
+	dashboardGroupStatsCache = newSnapshotCache(30 * time.Second)
+	dashboardSnapshotV2Cache = newSnapshotCache(30 * time.Second)
+}
+
+func TestDashboardHandler_GetUsageTrend_UsesCache(t *testing.T) {
+	t.Cleanup(resetDashboardReadCachesForTest)
+	resetDashboardReadCachesForTest()
+
+	gin.SetMode(gin.TestMode)
+	repo := &dashboardUsageRepoCacheProbe{}
+	dashboardSvc := service.NewDashboardService(repo, nil, nil, nil)
+	handler := NewDashboardHandler(dashboardSvc, nil)
+	router := gin.New()
+	router.GET("/admin/dashboard/trend", handler.GetUsageTrend)
+
+	req1 := httptest.NewRequest(http.MethodGet, "/admin/dashboard/trend?start_date=2026-03-01&end_date=2026-03-07&granularity=day", nil)
+	rec1 := httptest.NewRecorder()
+	router.ServeHTTP(rec1, req1)
+	require.Equal(t, http.StatusOK, rec1.Code)
+	require.Equal(t, "miss", rec1.Header().Get("X-Snapshot-Cache"))
+
+	req2 := httptest.NewRequest(http.MethodGet, "/admin/dashboard/trend?start_date=2026-03-01&end_date=2026-03-07&granularity=day", nil)
+	rec2 := httptest.NewRecorder()
+	router.ServeHTTP(rec2, req2)
+	require.Equal(t, http.StatusOK, rec2.Code)
+	require.Equal(t, "hit", rec2.Header().Get("X-Snapshot-Cache"))
+	require.Equal(t, int32(1), repo.trendCalls.Load())
+}
+
+func TestDashboardHandler_GetUserUsageTrend_UsesCache(t *testing.T) {
+	t.Cleanup(resetDashboardReadCachesForTest)
+	resetDashboardReadCachesForTest()
+
+	gin.SetMode(gin.TestMode)
+	repo := &dashboardUsageRepoCacheProbe{}
+	dashboardSvc := service.NewDashboardService(repo, nil, nil, nil)
+	handler := NewDashboardHandler(dashboardSvc, nil)
+	router := gin.New()
+	router.GET("/admin/dashboard/users-trend", handler.GetUserUsageTrend)
+
+	req1 := httptest.NewRequest(http.MethodGet, "/admin/dashboard/users-trend?start_date=2026-03-01&end_date=2026-03-07&granularity=day&limit=8", nil)
+	rec1 := httptest.NewRecorder()
+	router.ServeHTTP(rec1, req1)
+	require.Equal(t, http.StatusOK, rec1.Code)
+	require.Equal(t, "miss", rec1.Header().Get("X-Snapshot-Cache"))
+
+	req2 := httptest.NewRequest(http.MethodGet, "/admin/dashboard/users-trend?start_date=2026-03-01&end_date=2026-03-07&granularity=day&limit=8", nil)
+	rec2 := httptest.NewRecorder()
+	router.ServeHTTP(rec2, req2)
+	require.Equal(t, http.StatusOK, rec2.Code)
+	require.Equal(t, "hit", rec2.Header().Get("X-Snapshot-Cache"))
+	require.Equal(t, int32(1), repo.usersTrendCalls.Load())
+}

backend/internal/handler/admin/dashboard_query_cache.go

+package admin
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"time"
+
+	"github.com/Wei-Shaw/sub2api/internal/pkg/usagestats"
+)
+
+var (
+	dashboardTrendCache        = newSnapshotCache(30 * time.Second)
+	dashboardModelStatsCache   = newSnapshotCache(30 * time.Second)
+	dashboardGroupStatsCache   = newSnapshotCache(30 * time.Second)
+	dashboardUsersTrendCache   = newSnapshotCache(30 * time.Second)
+	dashboardAPIKeysTrendCache = newSnapshotCache(30 * time.Second)
+)
+
+type dashboardTrendCacheKey struct {
+	StartTime   string `json:"start_time"`
+	EndTime     string `json:"end_time"`
+	Granularity string `json:"granularity"`
+	UserID      int64  `json:"user_id"`
+	APIKeyID    int64  `json:"api_key_id"`
+	AccountID   int64  `json:"account_id"`
+	GroupID     int64  `json:"group_id"`
+	Model       string `json:"model"`
+	RequestType *int16 `json:"request_type"`
+	Stream      *bool  `json:"stream"`
+	BillingType *int8  `json:"billing_type"`
+}
+
+type dashboardModelGroupCacheKey struct {
+	StartTime   string `json:"start_time"`
+	EndTime     string `json:"end_time"`
+	UserID      int64  `json:"user_id"`
+	APIKeyID    int64  `json:"api_key_id"`
+	AccountID   int64  `json:"account_id"`
+	GroupID     int64  `json:"group_id"`
+	RequestType *int16 `json:"request_type"`
+	Stream      *bool  `json:"stream"`
+	BillingType *int8  `json:"billing_type"`
+}
+
+type dashboardEntityTrendCacheKey struct {
+	StartTime   string `json:"start_time"`
+	EndTime     string `json:"end_time"`
+	Granularity string `json:"granularity"`
+	Limit       int    `json:"limit"`
+}
+
+func cacheStatusValue(hit bool) string {
+	if hit {
+		return "hit"
+	}
+	return "miss"
+}
+
+func mustMarshalDashboardCacheKey(value any) string {
+	raw, err := json.Marshal(value)
+	if err != nil {
+		return ""
+	}
+	return string(raw)
+}
+
+func snapshotPayloadAs[T any](payload any) (T, error) {
+	typed, ok := payload.(T)
+	if !ok {
+		var zero T
+		return zero, fmt.Errorf("unexpected cache payload type %T", payload)
+	}
+	return typed, nil
+}
+
+func (h *DashboardHandler) getUsageTrendCached(
+	ctx context.Context,
+	startTime, endTime time.Time,
+	granularity string,
+	userID, apiKeyID, accountID, groupID int64,
+	model string,
+	requestType *int16,
+	stream *bool,
+	billingType *int8,
+) ([]usagestats.TrendDataPoint, bool, error) {
+	key := mustMarshalDashboardCacheKey(dashboardTrendCacheKey{
+		StartTime:   startTime.UTC().Format(time.RFC3339),
+		EndTime:     endTime.UTC().Format(time.RFC3339),
+		Granularity: granularity,
+		UserID:      userID,
+		APIKeyID:    apiKeyID,
+		AccountID:   accountID,
+		GroupID:     groupID,
+		Model:       model,
+		RequestType: requestType,
+		Stream:      stream,
+		BillingType: billingType,
+	})
+	entry, hit, err := dashboardTrendCache.GetOrLoad(key, func() (any, error) {
+		return h.dashboardService.GetUsageTrendWithFilters(ctx, startTime, endTime, granularity, userID, apiKeyID, accountID, groupID, model, requestType, stream, billingType)
+	})
+	if err != nil {
+		return nil, hit, err
+	}
+	trend, err := snapshotPayloadAs[[]usagestats.TrendDataPoint](entry.Payload)
+	return trend, hit, err
+}
+
+func (h *DashboardHandler) getModelStatsCached(
+	ctx context.Context,
+	startTime, endTime time.Time,
+	userID, apiKeyID, accountID, groupID int64,
+	requestType *int16,
+	stream *bool,
+	billingType *int8,
+) ([]usagestats.ModelStat, bool, error) {
+	key := mustMarshalDashboardCacheKey(dashboardModelGroupCacheKey{
+		StartTime:   startTime.UTC().Format(time.RFC3339),
+		EndTime:     endTime.UTC().Format(time.RFC3339),
+		UserID:      userID,
+		APIKeyID:    apiKeyID,
+		AccountID:   accountID,
+		GroupID:     groupID,
+		RequestType: requestType,
+		Stream:      stream,
+		BillingType: billingType,
+	})
+	entry, hit, err := dashboardModelStatsCache.GetOrLoad(key, func() (any, error) {
+		return h.dashboardService.GetModelStatsWithFilters(ctx, startTime, endTime, userID, apiKeyID, accountID, groupID, requestType, stream, billingType)
+	})
+	if err != nil {
+		return nil, hit, err
+	}
+	stats, err := snapshotPayloadAs[[]usagestats.ModelStat](entry.Payload)
+	return stats, hit, err
+}
+
+func (h *DashboardHandler) getGroupStatsCached(
+	ctx context.Context,
+	startTime, endTime time.Time,
+	userID, apiKeyID, accountID, groupID int64,
+	requestType *int16,
+	stream *bool,
+	billingType *int8,
+) ([]usagestats.GroupStat, bool, error) {
+	key := mustMarshalDashboardCacheKey(dashboardModelGroupCacheKey{
+		StartTime:   startTime.UTC().Format(time.RFC3339),
+		EndTime:     endTime.UTC().Format(time.RFC3339),
+		UserID:      userID,
+		APIKeyID:    apiKeyID,
+		AccountID:   accountID,
+		GroupID:     groupID,
+		RequestType: requestType,
+		Stream:      stream,
+		BillingType: billingType,
+	})
+	entry, hit, err := dashboardGroupStatsCache.GetOrLoad(key, func() (any, error) {
+		return h.dashboardService.GetGroupStatsWithFilters(ctx, startTime, endTime, userID, apiKeyID, accountID, groupID, requestType, stream, billingType)
+	})
+	if err != nil {
+		return nil, hit, err
+	}
+	stats, err := snapshotPayloadAs[[]usagestats.GroupStat](entry.Payload)
+	return stats, hit, err
+}
+
+func (h *DashboardHandler) getAPIKeyUsageTrendCached(ctx context.Context, startTime, endTime time.Time, granularity string, limit int) ([]usagestats.APIKeyUsageTrendPoint, bool, error) {
+	key := mustMarshalDashboardCacheKey(dashboardEntityTrendCacheKey{
+		StartTime:   startTime.UTC().Format(time.RFC3339),
+		EndTime:     endTime.UTC().Format(time.RFC3339),
+		Granularity: granularity,
+		Limit:       limit,
+	})
+	entry, hit, err := dashboardAPIKeysTrendCache.GetOrLoad(key, func() (any, error) {
+		return h.dashboardService.GetAPIKeyUsageTrend(ctx, startTime, endTime, granularity, limit)
+	})
+	if err != nil {
+		return nil, hit, err
+	}
+	trend, err := snapshotPayloadAs[[]usagestats.APIKeyUsageTrendPoint](entry.Payload)
+	return trend, hit, err
+}
+
+func (h *DashboardHandler) getUserUsageTrendCached(ctx context.Context, startTime, endTime time.Time, granularity string, limit int) ([]usagestats.UserUsageTrendPoint, bool, error) {
+	key := mustMarshalDashboardCacheKey(dashboardEntityTrendCacheKey{
+		StartTime:   startTime.UTC().Format(time.RFC3339),
+		EndTime:     endTime.UTC().Format(time.RFC3339),
+		Granularity: granularity,
+		Limit:       limit,
+	})
+	entry, hit, err := dashboardUsersTrendCache.GetOrLoad(key, func() (any, error) {
+		return h.dashboardService.GetUserUsageTrend(ctx, startTime, endTime, granularity, limit)
+	})
+	if err != nil {
+		return nil, hit, err
+	}
+	trend, err := snapshotPayloadAs[[]usagestats.UserUsageTrendPoint](entry.Payload)
+	return trend, hit, err
+}

backend/internal/handler/admin/dashboard_snapshot_v2_handler.go

 package admin
 
 import (
+	"context"
 	"encoding/json"
+	"errors"
 	"net/http"
 	"strconv"
 	"strings"
@@ -111,7 +113,25 @@ func (h *DashboardHandler) GetSnapshotV2(c *gin.Context) {
 	})
 	cacheKey := string(keyRaw)
 
-	if cached, ok := dashboardSnapshotV2Cache.Get(cacheKey); ok {
+	cached, hit, err := dashboardSnapshotV2Cache.GetOrLoad(cacheKey, func() (any, error) {
+		return h.buildSnapshotV2Response(
+			c.Request.Context(),
+			startTime,
+			endTime,
+			granularity,
+			filters,
+			includeStats,
+			includeTrend,
+			includeModels,
+			includeGroups,
+			includeUsersTrend,
+			usersTrendLimit,
+		)
+	})
+	if err != nil {
+		response.Error(c, 500, err.Error())
+		return
+	}
 	if cached.ETag != "" {
 		c.Header("ETag", cached.ETag)
 		c.Header("Vary", "If-None-Match")
@@ -120,11 +140,18 @@ func (h *DashboardHandler) GetSnapshotV2(c *gin.Context) {
 			return
 		}
 	}
-		c.Header("X-Snapshot-Cache", "hit")
+	c.Header("X-Snapshot-Cache", cacheStatusValue(hit))
 	response.Success(c, cached.Payload)
-		return
-	}
+}
 
+func (h *DashboardHandler) buildSnapshotV2Response(
+	ctx context.Context,
+	startTime, endTime time.Time,
+	granularity string,
+	filters *dashboardSnapshotV2Filters,
+	includeStats, includeTrend, includeModels, includeGroups, includeUsersTrend bool,
+	usersTrendLimit int,
+) (*dashboardSnapshotV2Response, error) {
 	resp := &dashboardSnapshotV2Response{
 		GeneratedAt: time.Now().UTC().Format(time.RFC3339),
 		StartDate:   startTime.Format("2006-01-02"),
@@ -133,10 +160,9 @@ func (h *DashboardHandler) GetSnapshotV2(c *gin.Context) {
 	}
 
 	if includeStats {
-		stats, err := h.dashboardService.GetDashboardStats(c.Request.Context())
+		stats, err := h.dashboardService.GetDashboardStats(ctx)
 		if err != nil {
-			response.Error(c, 500, "Failed to get dashboard statistics")
-			return
+			return nil, errors.New("failed to get dashboard statistics")
 		}
 		resp.Stats = &dashboardSnapshotV2Stats{
 			DashboardStats: *stats,
@@ -145,8 +171,8 @@ func (h *DashboardHandler) GetSnapshotV2(c *gin.Context) {
 	}
 
 	if includeTrend {
-		trend, err := h.dashboardService.GetUsageTrendWithFilters(
-			c.Request.Context(),
+		trend, _, err := h.getUsageTrendCached(
+			ctx,
 			startTime,
 			endTime,
 			granularity,
@@ -160,15 +186,14 @@ func (h *DashboardHandler) GetSnapshotV2(c *gin.Context) {
 			filters.BillingType,
 		)
 		if err != nil {
-			response.Error(c, 500, "Failed to get usage trend")
-			return
+			return nil, errors.New("failed to get usage trend")
 		}
 		resp.Trend = trend
 	}
 
 	if includeModels {
-		models, err := h.dashboardService.GetModelStatsWithFilters(
-			c.Request.Context(),
+		models, _, err := h.getModelStatsCached(
+			ctx,
 			startTime,
 			endTime,
 			filters.UserID,
@@ -180,15 +205,14 @@ func (h *DashboardHandler) GetSnapshotV2(c *gin.Context) {
 			filters.BillingType,
 		)
 		if err != nil {
-			response.Error(c, 500, "Failed to get model statistics")
-			return
+			return nil, errors.New("failed to get model statistics")
 		}
 		resp.Models = models
 	}
 
 	if includeGroups {
-		groups, err := h.dashboardService.GetGroupStatsWithFilters(
-			c.Request.Context(),
+		groups, _, err := h.getGroupStatsCached(
+			ctx,
 			startTime,
 			endTime,
 			filters.UserID,
@@ -200,34 +224,20 @@ func (h *DashboardHandler) GetSnapshotV2(c *gin.Context) {
 			filters.BillingType,
 		)
 		if err != nil {
-			response.Error(c, 500, "Failed to get group statistics")
-			return
+			return nil, errors.New("failed to get group statistics")
 		}
 		resp.Groups = groups
 	}
 
 	if includeUsersTrend {
-		usersTrend, err := h.dashboardService.GetUserUsageTrend(
-			c.Request.Context(),
-			startTime,
-			endTime,
-			granularity,
-			usersTrendLimit,
-		)
+		usersTrend, _, err := h.getUserUsageTrendCached(ctx, startTime, endTime, granularity, usersTrendLimit)
 		if err != nil {
-			response.Error(c, 500, "Failed to get user usage trend")
-			return
+			return nil, errors.New("failed to get user usage trend")
 		}
 		resp.UsersTrend = usersTrend
 	}
 
-	cached := dashboardSnapshotV2Cache.Set(cacheKey, resp)
-	if cached.ETag != "" {
-		c.Header("ETag", cached.ETag)
-		c.Header("Vary", "If-None-Match")
-	}
-	c.Header("X-Snapshot-Cache", "miss")
-	response.Success(c, resp)
+	return resp, nil
 }
 
 func parseDashboardSnapshotV2Filters(c *gin.Context) (*dashboardSnapshotV2Filters, error) {

backend/internal/handler/admin/ops_alerts_handler.go

@@ -23,6 +23,13 @@ var validOpsAlertMetricTypes = []string{
 	"cpu_usage_percent",
 	"memory_usage_percent",
 	"concurrency_queue_depth",
+	"group_available_accounts",
+	"group_available_ratio",
+	"group_rate_limit_ratio",
+	"account_rate_limited_count",
+	"account_error_count",
+	"account_error_ratio",
+	"overload_account_count",
 }
 
 var validOpsAlertMetricTypeSet = func() map[string]struct{} {
@@ -82,7 +89,10 @@ func isPercentOrRateMetric(metricType string) bool {
 		"error_rate",
 		"upstream_error_rate",
 		"cpu_usage_percent",
-		"memory_usage_percent":
+		"memory_usage_percent",
+		"group_available_ratio",
+		"group_rate_limit_ratio",
+		"account_error_ratio":
 		return true
 	default:
 		return false

backend/internal/handler/admin/snapshot_cache.go

@@ -7,6 +7,8 @@ import (
 	"strings"
 	"sync"
 	"time"
+
+	"golang.org/x/sync/singleflight"
 )
 
 type snapshotCacheEntry struct {
@@ -19,6 +21,12 @@ type snapshotCache struct {
 	mu    sync.RWMutex
 	ttl   time.Duration
 	items map[string]snapshotCacheEntry
+	sf    singleflight.Group
+}
+
+type snapshotCacheLoadResult struct {
+	Entry snapshotCacheEntry
+	Hit   bool
 }
 
 func newSnapshotCache(ttl time.Duration) *snapshotCache {
@@ -70,6 +78,41 @@ func (c *snapshotCache) Set(key string, payload any) snapshotCacheEntry {
 	return entry
 }
 
+func (c *snapshotCache) GetOrLoad(key string, load func() (any, error)) (snapshotCacheEntry, bool, error) {
+	if load == nil {
+		return snapshotCacheEntry{}, false, nil
+	}
+	if entry, ok := c.Get(key); ok {
+		return entry, true, nil
+	}
+	if c == nil || key == "" {
+		payload, err := load()
+		if err != nil {
+			return snapshotCacheEntry{}, false, err
+		}
+		return c.Set(key, payload), false, nil
+	}
+
+	value, err, _ := c.sf.Do(key, func() (any, error) {
+		if entry, ok := c.Get(key); ok {
+			return snapshotCacheLoadResult{Entry: entry, Hit: true}, nil
+		}
+		payload, err := load()
+		if err != nil {
+			return nil, err
+		}
+		return snapshotCacheLoadResult{Entry: c.Set(key, payload), Hit: false}, nil
+	})
+	if err != nil {
+		return snapshotCacheEntry{}, false, err
+	}
+	result, ok := value.(snapshotCacheLoadResult)
+	if !ok {
+		return snapshotCacheEntry{}, false, nil
+	}
+	return result.Entry, result.Hit, nil
+}
+
 func buildETagFromAny(payload any) string {
 	raw, err := json.Marshal(payload)
 	if err != nil {

backend/internal/handler/admin/snapshot_cache_test.go

@@ -3,6 +3,8 @@
 package admin
 
 import (
+	"sync"
+	"sync/atomic"
 	"testing"
 	"time"
 
@@ -95,6 +97,61 @@ func TestBuildETagFromAny_UnmarshalablePayload(t *testing.T) {
 	require.Empty(t, etag)
 }
 
+func TestSnapshotCache_GetOrLoad_MissThenHit(t *testing.T) {
+	c := newSnapshotCache(5 * time.Second)
+	var loads atomic.Int32
+
+	entry, hit, err := c.GetOrLoad("key1", func() (any, error) {
+		loads.Add(1)
+		return map[string]string{"hello": "world"}, nil
+	})
+	require.NoError(t, err)
+	require.False(t, hit)
+	require.NotEmpty(t, entry.ETag)
+	require.Equal(t, int32(1), loads.Load())
+
+	entry2, hit, err := c.GetOrLoad("key1", func() (any, error) {
+		loads.Add(1)
+		return map[string]string{"unexpected": "value"}, nil
+	})
+	require.NoError(t, err)
+	require.True(t, hit)
+	require.Equal(t, entry.ETag, entry2.ETag)
+	require.Equal(t, int32(1), loads.Load())
+}
+
+func TestSnapshotCache_GetOrLoad_ConcurrentSingleflight(t *testing.T) {
+	c := newSnapshotCache(5 * time.Second)
+	var loads atomic.Int32
+	start := make(chan struct{})
+	const callers = 8
+	errCh := make(chan error, callers)
+
+	var wg sync.WaitGroup
+	wg.Add(callers)
+	for range callers {
+		go func() {
+			defer wg.Done()
+			<-start
+			_, _, err := c.GetOrLoad("shared", func() (any, error) {
+				loads.Add(1)
+				time.Sleep(20 * time.Millisecond)
+				return "value", nil
+			})
+			errCh <- err
+		}()
+	}
+	close(start)
+	wg.Wait()
+	close(errCh)
+
+	for err := range errCh {
+		require.NoError(t, err)
+	}
+
+	require.Equal(t, int32(1), loads.Load())
+}
+
 func TestParseBoolQueryWithDefault(t *testing.T) {
 	tests := []struct {
 		name string

backend/internal/handler/admin/subscription_handler.go

@@ -216,6 +216,37 @@ func (h *SubscriptionHandler) Extend(c *gin.Context) {
 	})
 }
 
+// ResetSubscriptionQuotaRequest represents the reset quota request
+type ResetSubscriptionQuotaRequest struct {
+	Daily  bool `json:"daily"`
+	Weekly bool `json:"weekly"`
+}
+
+// ResetQuota resets daily and/or weekly usage for a subscription.
+// POST /api/v1/admin/subscriptions/:id/reset-quota
+func (h *SubscriptionHandler) ResetQuota(c *gin.Context) {
+	subscriptionID, err := strconv.ParseInt(c.Param("id"), 10, 64)
+	if err != nil {
+		response.BadRequest(c, "Invalid subscription ID")
+		return
+	}
+	var req ResetSubscriptionQuotaRequest
+	if err := c.ShouldBindJSON(&req); err != nil {
+		response.BadRequest(c, "Invalid request: "+err.Error())
+		return
+	}
+	if !req.Daily && !req.Weekly {
+		response.BadRequest(c, "At least one of 'daily' or 'weekly' must be true")
+		return
+	}
+	sub, err := h.subscriptionService.AdminResetQuota(c.Request.Context(), subscriptionID, req.Daily, req.Weekly)
+	if err != nil {
+		response.ErrorFrom(c, err)
+		return
+	}
+	response.Success(c, dto.UserSubscriptionFromServiceAdmin(sub))
+}
+
 // Revoke handles revoking a subscription
 // DELETE /api/v1/admin/subscriptions/:id
 func (h *SubscriptionHandler) Revoke(c *gin.Context) {

backend/internal/handler/openai_chat_completions.go

+package handler
+
+import (
+	"context"
+	"errors"
+	"net/http"
+	"time"
+
+	pkghttputil "github.com/Wei-Shaw/sub2api/internal/pkg/httputil"
+	"github.com/Wei-Shaw/sub2api/internal/pkg/ip"
+	"github.com/Wei-Shaw/sub2api/internal/pkg/logger"
+	middleware2 "github.com/Wei-Shaw/sub2api/internal/server/middleware"
+	"github.com/Wei-Shaw/sub2api/internal/service"
+	"github.com/gin-gonic/gin"
+	"github.com/tidwall/gjson"
+	"go.uber.org/zap"
+)
+
+// ChatCompletions handles OpenAI Chat Completions API requests.
+// POST /v1/chat/completions
+func (h *OpenAIGatewayHandler) ChatCompletions(c *gin.Context) {
+	streamStarted := false
+	defer h.recoverResponsesPanic(c, &streamStarted)
+
+	requestStart := time.Now()
+
+	apiKey, ok := middleware2.GetAPIKeyFromContext(c)
+	if !ok {
+		h.errorResponse(c, http.StatusUnauthorized, "authentication_error", "Invalid API key")
+		return
+	}
+
+	subject, ok := middleware2.GetAuthSubjectFromContext(c)
+	if !ok {
+		h.errorResponse(c, http.StatusInternalServerError, "api_error", "User context not found")
+		return
+	}
+	reqLog := requestLogger(
+		c,
+		"handler.openai_gateway.chat_completions",
+		zap.Int64("user_id", subject.UserID),
+		zap.Int64("api_key_id", apiKey.ID),
+		zap.Any("group_id", apiKey.GroupID),
+	)
+
+	if !h.ensureResponsesDependencies(c, reqLog) {
+		return
+	}
+
+	body, err := pkghttputil.ReadRequestBodyWithPrealloc(c.Request)
+	if err != nil {
+		if maxErr, ok := extractMaxBytesError(err); ok {
+			h.errorResponse(c, http.StatusRequestEntityTooLarge, "invalid_request_error", buildBodyTooLargeMessage(maxErr.Limit))
+			return
+		}
+		h.errorResponse(c, http.StatusBadRequest, "invalid_request_error", "Failed to read request body")
+		return
+	}
+	if len(body) == 0 {
+		h.errorResponse(c, http.StatusBadRequest, "invalid_request_error", "Request body is empty")
+		return
+	}
+
+	if !gjson.ValidBytes(body) {
+		h.errorResponse(c, http.StatusBadRequest, "invalid_request_error", "Failed to parse request body")
+		return
+	}
+
+	modelResult := gjson.GetBytes(body, "model")
+	if !modelResult.Exists() || modelResult.Type != gjson.String || modelResult.String() == "" {
+		h.errorResponse(c, http.StatusBadRequest, "invalid_request_error", "model is required")
+		return
+	}
+	reqModel := modelResult.String()
+	reqStream := gjson.GetBytes(body, "stream").Bool()
+
+	reqLog = reqLog.With(zap.String("model", reqModel), zap.Bool("stream", reqStream))
+
+	setOpsRequestContext(c, reqModel, reqStream, body)
+
+	if h.errorPassthroughService != nil {
+		service.BindErrorPassthroughService(c, h.errorPassthroughService)
+	}
+
+	subscription, _ := middleware2.GetSubscriptionFromContext(c)
+
+	service.SetOpsLatencyMs(c, service.OpsAuthLatencyMsKey, time.Since(requestStart).Milliseconds())
+	routingStart := time.Now()
+
+	userReleaseFunc, acquired := h.acquireResponsesUserSlot(c, subject.UserID, subject.Concurrency, reqStream, &streamStarted, reqLog)
+	if !acquired {
+		return
+	}
+	if userReleaseFunc != nil {
+		defer userReleaseFunc()
+	}
+
+	if err := h.billingCacheService.CheckBillingEligibility(c.Request.Context(), apiKey.User, apiKey, apiKey.Group, subscription); err != nil {
+		reqLog.Info("openai_chat_completions.billing_eligibility_check_failed", zap.Error(err))
+		status, code, message := billingErrorDetails(err)
+		h.handleStreamingAwareError(c, status, code, message, streamStarted)
+		return
+	}
+
+	sessionHash := h.gatewayService.GenerateSessionHash(c, body)
+	promptCacheKey := h.gatewayService.ExtractSessionID(c, body)
+
+	maxAccountSwitches := h.maxAccountSwitches
+	switchCount := 0
+	failedAccountIDs := make(map[int64]struct{})
+	sameAccountRetryCount := make(map[int64]int)
+	var lastFailoverErr *service.UpstreamFailoverError
+
+	for {
+		c.Set("openai_chat_completions_fallback_model", "")
+		reqLog.Debug("openai_chat_completions.account_selecting", zap.Int("excluded_account_count", len(failedAccountIDs)))
+		selection, scheduleDecision, err := h.gatewayService.SelectAccountWithScheduler(
+			c.Request.Context(),
+			apiKey.GroupID,
+			"",
+			sessionHash,
+			reqModel,
+			failedAccountIDs,
+			service.OpenAIUpstreamTransportAny,
+		)
+		if err != nil {
+			reqLog.Warn("openai_chat_completions.account_select_failed",
+				zap.Error(err),
+				zap.Int("excluded_account_count", len(failedAccountIDs)),
+			)
+			if len(failedAccountIDs) == 0 {
+				defaultModel := ""
+				if apiKey.Group != nil {
+					defaultModel = apiKey.Group.DefaultMappedModel
+				}
+				if defaultModel != "" && defaultModel != reqModel {
+					reqLog.Info("openai_chat_completions.fallback_to_default_model",
+						zap.String("default_mapped_model", defaultModel),
+					)
+					selection, scheduleDecision, err = h.gatewayService.SelectAccountWithScheduler(
+						c.Request.Context(),
+						apiKey.GroupID,
+						"",
+						sessionHash,
+						defaultModel,
+						failedAccountIDs,
+						service.OpenAIUpstreamTransportAny,
+					)
+					if err == nil && selection != nil {
+						c.Set("openai_chat_completions_fallback_model", defaultModel)
+					}
+				}
+				if err != nil {
+					h.handleStreamingAwareError(c, http.StatusServiceUnavailable, "api_error", "Service temporarily unavailable", streamStarted)
+					return
+				}
+			} else {
+				if lastFailoverErr != nil {
+					h.handleFailoverExhausted(c, lastFailoverErr, streamStarted)
+				} else {
+					h.handleStreamingAwareError(c, http.StatusBadGateway, "api_error", "Upstream request failed", streamStarted)
+				}
+				return
+			}
+		}
+		if selection == nil || selection.Account == nil {
+			h.handleStreamingAwareError(c, http.StatusServiceUnavailable, "api_error", "No available accounts", streamStarted)
+			return
+		}
+		account := selection.Account
+		sessionHash = ensureOpenAIPoolModeSessionHash(sessionHash, account)
+		reqLog.Debug("openai_chat_completions.account_selected", zap.Int64("account_id", account.ID), zap.String("account_name", account.Name))
+		_ = scheduleDecision
+		setOpsSelectedAccount(c, account.ID, account.Platform)
+
+		accountReleaseFunc, acquired := h.acquireResponsesAccountSlot(c, apiKey.GroupID, sessionHash, selection, reqStream, &streamStarted, reqLog)
+		if !acquired {
+			return
+		}
+
+		service.SetOpsLatencyMs(c, service.OpsRoutingLatencyMsKey, time.Since(routingStart).Milliseconds())
+		forwardStart := time.Now()
+
+		defaultMappedModel := ""
+		if apiKey.Group != nil {
+			defaultMappedModel = apiKey.Group.DefaultMappedModel
+		}
+		if fallbackModel := c.GetString("openai_chat_completions_fallback_model"); fallbackModel != "" {
+			defaultMappedModel = fallbackModel
+		}
+		result, err := h.gatewayService.ForwardAsChatCompletions(c.Request.Context(), c, account, body, promptCacheKey, defaultMappedModel)
+
+		forwardDurationMs := time.Since(forwardStart).Milliseconds()
+		if accountReleaseFunc != nil {
+			accountReleaseFunc()
+		}
+		upstreamLatencyMs, _ := getContextInt64(c, service.OpsUpstreamLatencyMsKey)
+		responseLatencyMs := forwardDurationMs
+		if upstreamLatencyMs > 0 && forwardDurationMs > upstreamLatencyMs {
+			responseLatencyMs = forwardDurationMs - upstreamLatencyMs
+		}
+		service.SetOpsLatencyMs(c, service.OpsResponseLatencyMsKey, responseLatencyMs)
+		if err == nil && result != nil && result.FirstTokenMs != nil {
+			service.SetOpsLatencyMs(c, service.OpsTimeToFirstTokenMsKey, int64(*result.FirstTokenMs))
+		}
+		if err != nil {
+			var failoverErr *service.UpstreamFailoverError
+			if errors.As(err, &failoverErr) {
+				h.gatewayService.ReportOpenAIAccountScheduleResult(account.ID, false, nil)
+				// Pool mode: retry on the same account
+				if failoverErr.RetryableOnSameAccount {
+					retryLimit := account.GetPoolModeRetryCount()
+					if sameAccountRetryCount[account.ID] < retryLimit {
+						sameAccountRetryCount[account.ID]++
+						reqLog.Warn("openai_chat_completions.pool_mode_same_account_retry",
+							zap.Int64("account_id", account.ID),
+							zap.Int("upstream_status", failoverErr.StatusCode),
+							zap.Int("retry_limit", retryLimit),
+							zap.Int("retry_count", sameAccountRetryCount[account.ID]),
+						)
+						select {
+						case <-c.Request.Context().Done():
+							return
+						case <-time.After(sameAccountRetryDelay):
+						}
+						continue
+					}
+				}
+				h.gatewayService.RecordOpenAIAccountSwitch()
+				failedAccountIDs[account.ID] = struct{}{}
+				lastFailoverErr = failoverErr
+				if switchCount >= maxAccountSwitches {
+					h.handleFailoverExhausted(c, failoverErr, streamStarted)
+					return
+				}
+				switchCount++
+				reqLog.Warn("openai_chat_completions.upstream_failover_switching",
+					zap.Int64("account_id", account.ID),
+					zap.Int("upstream_status", failoverErr.StatusCode),
+					zap.Int("switch_count", switchCount),
+					zap.Int("max_switches", maxAccountSwitches),
+				)
+				continue
+			}
+			h.gatewayService.ReportOpenAIAccountScheduleResult(account.ID, false, nil)
+			wroteFallback := h.ensureForwardErrorResponse(c, streamStarted)
+			reqLog.Warn("openai_chat_completions.forward_failed",
+				zap.Int64("account_id", account.ID),
+				zap.Bool("fallback_error_response_written", wroteFallback),
+				zap.Error(err),
+			)
+			return
+		}
+		if result != nil {
+			h.gatewayService.ReportOpenAIAccountScheduleResult(account.ID, true, result.FirstTokenMs)
+		} else {
+			h.gatewayService.ReportOpenAIAccountScheduleResult(account.ID, true, nil)
+		}
+
+		userAgent := c.GetHeader("User-Agent")
+		clientIP := ip.GetClientIP(c)
+
+		h.submitUsageRecordTask(func(ctx context.Context) {
+			if err := h.gatewayService.RecordUsage(ctx, &service.OpenAIRecordUsageInput{
+				Result:        result,
+				APIKey:        apiKey,
+				User:          apiKey.User,
+				Account:       account,
+				Subscription:  subscription,
+				UserAgent:     userAgent,
+				IPAddress:     clientIP,
+				APIKeyService: h.apiKeyService,
+			}); err != nil {
+				logger.L().With(
+					zap.String("component", "handler.openai_gateway.chat_completions"),
+					zap.Int64("user_id", subject.UserID),
+					zap.Int64("api_key_id", apiKey.ID),
+					zap.Any("group_id", apiKey.GroupID),
+					zap.String("model", reqModel),
+					zap.Int64("account_id", account.ID),
+				).Error("openai_chat_completions.record_usage_failed", zap.Error(err))
+			}
+		})
+		reqLog.Debug("openai_chat_completions.request_completed",
+			zap.Int64("account_id", account.ID),
+			zap.Int("switch_count", switchCount),
+		)
+		return
+	}
+}

backend/internal/handler/ops_error_logger.go

@@ -31,6 +31,7 @@ const (
 const (
 	opsErrorLogTimeout      = 5 * time.Second
 	opsErrorLogDrainTimeout = 10 * time.Second
+	opsErrorLogBatchWindow  = 200 * time.Millisecond
 
 	opsErrorLogMinWorkerCount = 4
 	opsErrorLogMaxWorkerCount = 32
@@ -38,6 +39,7 @@ const (
 	opsErrorLogQueueSizePerWorker = 128
 	opsErrorLogMinQueueSize       = 256
 	opsErrorLogMaxQueueSize       = 8192
+	opsErrorLogBatchSize          = 32
 )
 
 type opsErrorLogJob struct {
@@ -82,25 +84,80 @@ func startOpsErrorLogWorkers() {
 	for i := 0; i < workerCount; i++ {
 		go func() {
 			defer opsErrorLogWorkersWg.Done()
-			for job := range opsErrorLogQueue {
+			for {
+				job, ok := <-opsErrorLogQueue
+				if !ok {
+					return
+				}
 				opsErrorLogQueueLen.Add(-1)
-				if job.ops == nil || job.entry == nil {
-					continue
+				batch := make([]opsErrorLogJob, 0, opsErrorLogBatchSize)
+				batch = append(batch, job)
+
+				timer := time.NewTimer(opsErrorLogBatchWindow)
+			batchLoop:
+				for len(batch) < opsErrorLogBatchSize {
+					select {
+					case nextJob, ok := <-opsErrorLogQueue:
+						if !ok {
+							if !timer.Stop() {
+								select {
+								case <-timer.C:
+								default:
+								}
+							}
+							flushOpsErrorLogBatch(batch)
+							return
+						}
+						opsErrorLogQueueLen.Add(-1)
+						batch = append(batch, nextJob)
+					case <-timer.C:
+						break batchLoop
+					}
+				}
+				if !timer.Stop() {
+					select {
+					case <-timer.C:
+					default:
+					}
+				}
+				flushOpsErrorLogBatch(batch)
+			}
+		}()
+	}
+}
+
+func flushOpsErrorLogBatch(batch []opsErrorLogJob) {
+	if len(batch) == 0 {
+		return
 	}
-				func() {
 	defer func() {
 		if r := recover(); r != nil {
 			log.Printf("[OpsErrorLogger] worker panic: %v\n%s", r, debug.Stack())
 		}
 	}()
+
+	grouped := make(map[*service.OpsService][]*service.OpsInsertErrorLogInput, len(batch))
+	var processed int64
+	for _, job := range batch {
+		if job.ops == nil || job.entry == nil {
+			continue
+		}
+		grouped[job.ops] = append(grouped[job.ops], job.entry)
+		processed++
+	}
+	if processed == 0 {
+		return
+	}
+
+	for opsSvc, entries := range grouped {
+		if opsSvc == nil || len(entries) == 0 {
+			continue
+		}
 		ctx, cancel := context.WithTimeout(context.Background(), opsErrorLogTimeout)
-					_ = job.ops.RecordError(ctx, job.entry, nil)
+		_ = opsSvc.RecordErrorBatch(ctx, entries)
 		cancel()
-					opsErrorLogProcessed.Add(1)
-				}()
-			}
-		}()
 	}
+	opsErrorLogProcessed.Add(processed)
 }
 
 func enqueueOpsErrorLog(ops *service.OpsService, entry *service.OpsInsertErrorLogInput) {

backend/internal/pkg/antigravity/claude_types.go

@@ -159,6 +159,8 @@ var claudeModels = []modelDef{
 // Antigravity 支持的 Gemini 模型
 var geminiModels = []modelDef{
 	{ID: "gemini-2.5-flash", DisplayName: "Gemini 2.5 Flash", CreatedAt: "2025-01-01T00:00:00Z"},
+	{ID: "gemini-2.5-flash-image", DisplayName: "Gemini 2.5 Flash Image", CreatedAt: "2025-01-01T00:00:00Z"},
+	{ID: "gemini-2.5-flash-image-preview", DisplayName: "Gemini 2.5 Flash Image Preview", CreatedAt: "2025-01-01T00:00:00Z"},
 	{ID: "gemini-2.5-flash-lite", DisplayName: "Gemini 2.5 Flash Lite", CreatedAt: "2025-01-01T00:00:00Z"},
 	{ID: "gemini-2.5-flash-thinking", DisplayName: "Gemini 2.5 Flash Thinking", CreatedAt: "2025-01-01T00:00:00Z"},
 	{ID: "gemini-3-flash", DisplayName: "Gemini 3 Flash", CreatedAt: "2025-06-01T00:00:00Z"},

backend/internal/pkg/antigravity/claude_types_test.go

@@ -13,6 +13,8 @@ func TestDefaultModels_ContainsNewAndLegacyImageModels(t *testing.T) {
 
 	requiredIDs := []string{
 		"claude-opus-4-6-thinking",
+		"gemini-2.5-flash-image",
+		"gemini-2.5-flash-image-preview",
 		"gemini-3.1-flash-image",
 		"gemini-3.1-flash-image-preview",
 		"gemini-3-pro-image", // legacy compatibility

backend/internal/pkg/apicompat/chatcompletions_to_responses.go

+package apicompat
+
+import (
+	"encoding/json"
+	"fmt"
+)
+
+// ChatCompletionsToResponses converts a Chat Completions request into a
+// Responses API request. The upstream always streams, so Stream is forced to
+// true. store is always false and reasoning.encrypted_content is always
+// included so that the response translator has full context.
+func ChatCompletionsToResponses(req *ChatCompletionsRequest) (*ResponsesRequest, error) {
+	input, err := convertChatMessagesToResponsesInput(req.Messages)
+	if err != nil {
+		return nil, err
+	}
+
+	inputJSON, err := json.Marshal(input)
+	if err != nil {
+		return nil, err
+	}
+
+	out := &ResponsesRequest{
+		Model:       req.Model,
+		Input:       inputJSON,
+		Temperature: req.Temperature,
+		TopP:        req.TopP,
+		Stream:      true, // upstream always streams
+		Include:     []string{"reasoning.encrypted_content"},
+		ServiceTier: req.ServiceTier,
+	}
+
+	storeFalse := false
+	out.Store = &storeFalse
+
+	// max_tokens / max_completion_tokens → max_output_tokens, prefer max_completion_tokens
+	maxTokens := 0
+	if req.MaxTokens != nil {
+		maxTokens = *req.MaxTokens
+	}
+	if req.MaxCompletionTokens != nil {
+		maxTokens = *req.MaxCompletionTokens
+	}
+	if maxTokens > 0 {
+		v := maxTokens
+		if v < minMaxOutputTokens {
+			v = minMaxOutputTokens
+		}
+		out.MaxOutputTokens = &v
+	}
+
+	// reasoning_effort → reasoning.effort + reasoning.summary="auto"
+	if req.ReasoningEffort != "" {
+		out.Reasoning = &ResponsesReasoning{
+			Effort:  req.ReasoningEffort,
+			Summary: "auto",
+		}
+	}
+
+	// tools[] and legacy functions[] → ResponsesTool[]
+	if len(req.Tools) > 0 || len(req.Functions) > 0 {
+		out.Tools = convertChatToolsToResponses(req.Tools, req.Functions)
+	}
+
+	// tool_choice: already compatible format — pass through directly.
+	// Legacy function_call needs mapping.
+	if len(req.ToolChoice) > 0 {
+		out.ToolChoice = req.ToolChoice
+	} else if len(req.FunctionCall) > 0 {
+		tc, err := convertChatFunctionCallToToolChoice(req.FunctionCall)
+		if err != nil {
+			return nil, fmt.Errorf("convert function_call: %w", err)
+		}
+		out.ToolChoice = tc
+	}
+
+	return out, nil
+}
+
+// convertChatMessagesToResponsesInput converts the Chat Completions messages
+// array into a Responses API input items array.
+func convertChatMessagesToResponsesInput(msgs []ChatMessage) ([]ResponsesInputItem, error) {
+	var out []ResponsesInputItem
+	for _, m := range msgs {
+		items, err := chatMessageToResponsesItems(m)
+		if err != nil {
+			return nil, err
+		}
+		out = append(out, items...)
+	}
+	return out, nil
+}
+
+// chatMessageToResponsesItems converts a single ChatMessage into one or more
+// ResponsesInputItem values.
+func chatMessageToResponsesItems(m ChatMessage) ([]ResponsesInputItem, error) {
+	switch m.Role {
+	case "system":
+		return chatSystemToResponses(m)
+	case "user":
+		return chatUserToResponses(m)
+	case "assistant":
+		return chatAssistantToResponses(m)
+	case "tool":
+		return chatToolToResponses(m)
+	case "function":
+		return chatFunctionToResponses(m)
+	default:
+		return chatUserToResponses(m)
+	}
+}
+
+// chatSystemToResponses converts a system message.
+func chatSystemToResponses(m ChatMessage) ([]ResponsesInputItem, error) {
+	text, err := parseChatContent(m.Content)
+	if err != nil {
+		return nil, err
+	}
+	content, err := json.Marshal(text)
+	if err != nil {
+		return nil, err
+	}
+	return []ResponsesInputItem{{Role: "system", Content: content}}, nil
+}
+
+// chatUserToResponses converts a user message, handling both plain strings and
+// multi-modal content arrays.
+func chatUserToResponses(m ChatMessage) ([]ResponsesInputItem, error) {
+	// Try plain string first.
+	var s string
+	if err := json.Unmarshal(m.Content, &s); err == nil {
+		content, _ := json.Marshal(s)
+		return []ResponsesInputItem{{Role: "user", Content: content}}, nil
+	}
+
+	var parts []ChatContentPart
+	if err := json.Unmarshal(m.Content, &parts); err != nil {
+		return nil, fmt.Errorf("parse user content: %w", err)
+	}
+
+	var responseParts []ResponsesContentPart
+	for _, p := range parts {
+		switch p.Type {
+		case "text":
+			if p.Text != "" {
+				responseParts = append(responseParts, ResponsesContentPart{
+					Type: "input_text",
+					Text: p.Text,
+				})
+			}
+		case "image_url":
+			if p.ImageURL != nil && p.ImageURL.URL != "" {
+				responseParts = append(responseParts, ResponsesContentPart{
+					Type:     "input_image",
+					ImageURL: p.ImageURL.URL,
+				})
+			}
+		}
+	}
+
+	content, err := json.Marshal(responseParts)
+	if err != nil {
+		return nil, err
+	}
+	return []ResponsesInputItem{{Role: "user", Content: content}}, nil
+}
+
+// chatAssistantToResponses converts an assistant message. If there is both
+// text content and tool_calls, the text is emitted as an assistant message
+// first, then each tool_call becomes a function_call item. If the content is
+// empty/nil and there are tool_calls, only function_call items are emitted.
+func chatAssistantToResponses(m ChatMessage) ([]ResponsesInputItem, error) {
+	var items []ResponsesInputItem
+
+	// Emit assistant message with output_text if content is non-empty.
+	if len(m.Content) > 0 {
+		var s string
+		if err := json.Unmarshal(m.Content, &s); err == nil && s != "" {
+			parts := []ResponsesContentPart{{Type: "output_text", Text: s}}
+			partsJSON, err := json.Marshal(parts)
+			if err != nil {
+				return nil, err
+			}
+			items = append(items, ResponsesInputItem{Role: "assistant", Content: partsJSON})
+		}
+	}
+
+	// Emit one function_call item per tool_call.
+	for _, tc := range m.ToolCalls {
+		args := tc.Function.Arguments
+		if args == "" {
+			args = "{}"
+		}
+		items = append(items, ResponsesInputItem{
+			Type:      "function_call",
+			CallID:    tc.ID,
+			Name:      tc.Function.Name,
+			Arguments: args,
+			ID:        tc.ID,
+		})
+	}
+
+	return items, nil
+}
+
+// chatToolToResponses converts a tool result message (role=tool) into a
+// function_call_output item.
+func chatToolToResponses(m ChatMessage) ([]ResponsesInputItem, error) {
+	output, err := parseChatContent(m.Content)
+	if err != nil {
+		return nil, err
+	}
+	if output == "" {
+		output = "(empty)"
+	}
+	return []ResponsesInputItem{{
+		Type:   "function_call_output",
+		CallID: m.ToolCallID,
+		Output: output,
+	}}, nil
+}
+
+// chatFunctionToResponses converts a legacy function result message
+// (role=function) into a function_call_output item. The Name field is used as
+// call_id since legacy function calls do not carry a separate call_id.
+func chatFunctionToResponses(m ChatMessage) ([]ResponsesInputItem, error) {
+	output, err := parseChatContent(m.Content)
+	if err != nil {
+		return nil, err
+	}
+	if output == "" {
+		output = "(empty)"
+	}
+	return []ResponsesInputItem{{
+		Type:   "function_call_output",
+		CallID: m.Name,
+		Output: output,
+	}}, nil
+}
+
+// parseChatContent returns the string value of a ChatMessage Content field.
+// Content must be a JSON string. Returns "" if content is null or empty.
+func parseChatContent(raw json.RawMessage) (string, error) {
+	if len(raw) == 0 {
+		return "", nil
+	}
+	var s string
+	if err := json.Unmarshal(raw, &s); err != nil {
+		return "", fmt.Errorf("parse content as string: %w", err)
+	}
+	return s, nil
+}
+
+// convertChatToolsToResponses maps Chat Completions tool definitions and legacy
+// function definitions to Responses API tool definitions.
+func convertChatToolsToResponses(tools []ChatTool, functions []ChatFunction) []ResponsesTool {
+	var out []ResponsesTool
+
+	for _, t := range tools {
+		if t.Type != "function" || t.Function == nil {
+			continue
+		}
+		rt := ResponsesTool{
+			Type:        "function",
+			Name:        t.Function.Name,
+			Description: t.Function.Description,
+			Parameters:  t.Function.Parameters,
+			Strict:      t.Function.Strict,
+		}
+		out = append(out, rt)
+	}
+
+	// Legacy functions[] are treated as function-type tools.
+	for _, f := range functions {
+		rt := ResponsesTool{
+			Type:        "function",
+			Name:        f.Name,
+			Description: f.Description,
+			Parameters:  f.Parameters,
+			Strict:      f.Strict,
+		}
+		out = append(out, rt)
+	}
+
+	return out
+}
+
+// convertChatFunctionCallToToolChoice maps the legacy function_call field to a
+// Responses API tool_choice value.
+//
+//	"auto" → "auto"
+//	"none" → "none"
+//	{"name":"X"} → {"type":"function","function":{"name":"X"}}
+func convertChatFunctionCallToToolChoice(raw json.RawMessage) (json.RawMessage, error) {
+	// Try string first ("auto", "none", etc.) — pass through as-is.
+	var s string
+	if err := json.Unmarshal(raw, &s); err == nil {
+		return json.Marshal(s)
+	}
+
+	// Object form: {"name":"X"}
+	var obj struct {
+		Name string `json:"name"`
+	}
+	if err := json.Unmarshal(raw, &obj); err != nil {
+		return nil, err
+	}
+	return json.Marshal(map[string]any{
+		"type":     "function",
+		"function": map[string]string{"name": obj.Name},
+	})
+}

backend/internal/pkg/apicompat/responses_to_chatcompletions.go

+package apicompat
+
+import (
+	"crypto/rand"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"time"
+)
+
+// ---------------------------------------------------------------------------
+// Non-streaming: ResponsesResponse → ChatCompletionsResponse
+// ---------------------------------------------------------------------------
+
+// ResponsesToChatCompletions converts a Responses API response into a Chat
+// Completions response. Text output items are concatenated into
+// choices[0].message.content; function_call items become tool_calls.
+func ResponsesToChatCompletions(resp *ResponsesResponse, model string) *ChatCompletionsResponse {
+	id := resp.ID
+	if id == "" {
+		id = generateChatCmplID()
+	}
+
+	out := &ChatCompletionsResponse{
+		ID:      id,
+		Object:  "chat.completion",
+		Created: time.Now().Unix(),
+		Model:   model,
+	}
+
+	var contentText string
+	var toolCalls []ChatToolCall
+
+	for _, item := range resp.Output {
+		switch item.Type {
+		case "message":
+			for _, part := range item.Content {
+				if part.Type == "output_text" && part.Text != "" {
+					contentText += part.Text
+				}
+			}
+		case "function_call":
+			toolCalls = append(toolCalls, ChatToolCall{
+				ID:   item.CallID,
+				Type: "function",
+				Function: ChatFunctionCall{
+					Name:      item.Name,
+					Arguments: item.Arguments,
+				},
+			})
+		case "reasoning":
+			for _, s := range item.Summary {
+				if s.Type == "summary_text" && s.Text != "" {
+					contentText += s.Text
+				}
+			}
+		case "web_search_call":
+			// silently consumed — results already incorporated into text output
+		}
+	}
+
+	msg := ChatMessage{Role: "assistant"}
+	if len(toolCalls) > 0 {
+		msg.ToolCalls = toolCalls
+	}
+	if contentText != "" {
+		raw, _ := json.Marshal(contentText)
+		msg.Content = raw
+	}
+
+	finishReason := responsesStatusToChatFinishReason(resp.Status, resp.IncompleteDetails, toolCalls)
+
+	out.Choices = []ChatChoice{{
+		Index:        0,
+		Message:      msg,
+		FinishReason: finishReason,
+	}}
+
+	if resp.Usage != nil {
+		usage := &ChatUsage{
+			PromptTokens:     resp.Usage.InputTokens,
+			CompletionTokens: resp.Usage.OutputTokens,
+			TotalTokens:      resp.Usage.InputTokens + resp.Usage.OutputTokens,
+		}
+		if resp.Usage.InputTokensDetails != nil && resp.Usage.InputTokensDetails.CachedTokens > 0 {
+			usage.PromptTokensDetails = &ChatTokenDetails{
+				CachedTokens: resp.Usage.InputTokensDetails.CachedTokens,
+			}
+		}
+		out.Usage = usage
+	}
+
+	return out
+}
+
+func responsesStatusToChatFinishReason(status string, details *ResponsesIncompleteDetails, toolCalls []ChatToolCall) string {
+	switch status {
+	case "incomplete":
+		if details != nil && details.Reason == "max_output_tokens" {
+			return "length"
+		}
+		return "stop"
+	case "completed":
+		if len(toolCalls) > 0 {
+			return "tool_calls"
+		}
+		return "stop"
+	default:
+		return "stop"
+	}
+}
+
+// ---------------------------------------------------------------------------
+// Streaming: ResponsesStreamEvent → []ChatCompletionsChunk (stateful converter)
+// ---------------------------------------------------------------------------
+
+// ResponsesEventToChatState tracks state for converting a sequence of Responses
+// SSE events into Chat Completions SSE chunks.
+type ResponsesEventToChatState struct {
+	ID                     string
+	Model                  string
+	Created                int64
+	SentRole               bool
+	SawToolCall            bool
+	SawText                bool
+	Finalized              bool        // true after finish chunk has been emitted
+	NextToolCallIndex      int         // next sequential tool_call index to assign
+	OutputIndexToToolIndex map[int]int // Responses output_index → Chat tool_calls index
+	IncludeUsage           bool
+	Usage                  *ChatUsage
+}
+
+// NewResponsesEventToChatState returns an initialised stream state.
+func NewResponsesEventToChatState() *ResponsesEventToChatState {
+	return &ResponsesEventToChatState{
+		ID:                     generateChatCmplID(),
+		Created:                time.Now().Unix(),
+		OutputIndexToToolIndex: make(map[int]int),
+	}
+}
+
+// ResponsesEventToChatChunks converts a single Responses SSE event into zero
+// or more Chat Completions chunks, updating state as it goes.
+func ResponsesEventToChatChunks(evt *ResponsesStreamEvent, state *ResponsesEventToChatState) []ChatCompletionsChunk {
+	switch evt.Type {
+	case "response.created":
+		return resToChatHandleCreated(evt, state)
+	case "response.output_text.delta":
+		return resToChatHandleTextDelta(evt, state)
+	case "response.output_item.added":
+		return resToChatHandleOutputItemAdded(evt, state)
+	case "response.function_call_arguments.delta":
+		return resToChatHandleFuncArgsDelta(evt, state)
+	case "response.reasoning_summary_text.delta":
+		return resToChatHandleReasoningDelta(evt, state)
+	case "response.completed", "response.incomplete", "response.failed":
+		return resToChatHandleCompleted(evt, state)
+	default:
+		return nil
+	}
+}
+
+// FinalizeResponsesChatStream emits a final chunk with finish_reason if the
+// stream ended without a proper completion event (e.g. upstream disconnect).
+// It is idempotent: if a completion event already emitted the finish chunk,
+// this returns nil.
+func FinalizeResponsesChatStream(state *ResponsesEventToChatState) []ChatCompletionsChunk {
+	if state.Finalized {
+		return nil
+	}
+	state.Finalized = true
+
+	finishReason := "stop"
+	if state.SawToolCall {
+		finishReason = "tool_calls"
+	}
+
+	chunks := []ChatCompletionsChunk{makeChatFinishChunk(state, finishReason)}
+
+	if state.IncludeUsage && state.Usage != nil {
+		chunks = append(chunks, ChatCompletionsChunk{
+			ID:      state.ID,
+			Object:  "chat.completion.chunk",
+			Created: state.Created,
+			Model:   state.Model,
+			Choices: []ChatChunkChoice{},
+			Usage:   state.Usage,
+		})
+	}
+
+	return chunks
+}
+
+// ChatChunkToSSE formats a ChatCompletionsChunk as an SSE data line.
+func ChatChunkToSSE(chunk ChatCompletionsChunk) (string, error) {
+	data, err := json.Marshal(chunk)
+	if err != nil {
+		return "", err
+	}
+	return fmt.Sprintf("data: %s\n\n", data), nil
+}
+
+// --- internal handlers ---
+
+func resToChatHandleCreated(evt *ResponsesStreamEvent, state *ResponsesEventToChatState) []ChatCompletionsChunk {
+	if evt.Response != nil {
+		if evt.Response.ID != "" {
+			state.ID = evt.Response.ID
+		}
+		if state.Model == "" && evt.Response.Model != "" {
+			state.Model = evt.Response.Model
+		}
+	}
+	// Emit the role chunk.
+	if state.SentRole {
+		return nil
+	}
+	state.SentRole = true
+
+	role := "assistant"
+	return []ChatCompletionsChunk{makeChatDeltaChunk(state, ChatDelta{Role: role})}
+}
+
+func resToChatHandleTextDelta(evt *ResponsesStreamEvent, state *ResponsesEventToChatState) []ChatCompletionsChunk {
+	if evt.Delta == "" {
+		return nil
+	}
+	state.SawText = true
+	content := evt.Delta
+	return []ChatCompletionsChunk{makeChatDeltaChunk(state, ChatDelta{Content: &content})}
+}
+
+func resToChatHandleOutputItemAdded(evt *ResponsesStreamEvent, state *ResponsesEventToChatState) []ChatCompletionsChunk {
+	if evt.Item == nil || evt.Item.Type != "function_call" {
+		return nil
+	}
+
+	state.SawToolCall = true
+	idx := state.NextToolCallIndex
+	state.OutputIndexToToolIndex[evt.OutputIndex] = idx
+	state.NextToolCallIndex++
+
+	return []ChatCompletionsChunk{makeChatDeltaChunk(state, ChatDelta{
+		ToolCalls: []ChatToolCall{{
+			Index: &idx,
+			ID:    evt.Item.CallID,
+			Type:  "function",
+			Function: ChatFunctionCall{
+				Name: evt.Item.Name,
+			},
+		}},
+	})}
+}
+
+func resToChatHandleFuncArgsDelta(evt *ResponsesStreamEvent, state *ResponsesEventToChatState) []ChatCompletionsChunk {
+	if evt.Delta == "" {
+		return nil
+	}
+
+	idx, ok := state.OutputIndexToToolIndex[evt.OutputIndex]
+	if !ok {
+		return nil
+	}
+
+	return []ChatCompletionsChunk{makeChatDeltaChunk(state, ChatDelta{
+		ToolCalls: []ChatToolCall{{
+			Index: &idx,
+			Function: ChatFunctionCall{
+				Arguments: evt.Delta,
+			},
+		}},
+	})}
+}
+
+func resToChatHandleReasoningDelta(evt *ResponsesStreamEvent, state *ResponsesEventToChatState) []ChatCompletionsChunk {
+	if evt.Delta == "" {
+		return nil
+	}
+	content := evt.Delta
+	return []ChatCompletionsChunk{makeChatDeltaChunk(state, ChatDelta{Content: &content})}
+}
+
+func resToChatHandleCompleted(evt *ResponsesStreamEvent, state *ResponsesEventToChatState) []ChatCompletionsChunk {
+	state.Finalized = true
+	finishReason := "stop"
+
+	if evt.Response != nil {
+		if evt.Response.Usage != nil {
+			u := evt.Response.Usage
+			usage := &ChatUsage{
+				PromptTokens:     u.InputTokens,
+				CompletionTokens: u.OutputTokens,
+				TotalTokens:      u.InputTokens + u.OutputTokens,
+			}
+			if u.InputTokensDetails != nil && u.InputTokensDetails.CachedTokens > 0 {
+				usage.PromptTokensDetails = &ChatTokenDetails{
+					CachedTokens: u.InputTokensDetails.CachedTokens,
+				}
+			}
+			state.Usage = usage
+		}
+
+		switch evt.Response.Status {
+		case "incomplete":
+			if evt.Response.IncompleteDetails != nil && evt.Response.IncompleteDetails.Reason == "max_output_tokens" {
+				finishReason = "length"
+			}
+		case "completed":
+			if state.SawToolCall {
+				finishReason = "tool_calls"
+			}
+		}
+	} else if state.SawToolCall {
+		finishReason = "tool_calls"
+	}
+
+	var chunks []ChatCompletionsChunk
+	chunks = append(chunks, makeChatFinishChunk(state, finishReason))
+
+	if state.IncludeUsage && state.Usage != nil {
+		chunks = append(chunks, ChatCompletionsChunk{
+			ID:      state.ID,
+			Object:  "chat.completion.chunk",
+			Created: state.Created,
+			Model:   state.Model,
+			Choices: []ChatChunkChoice{},
+			Usage:   state.Usage,
+		})
+	}
+
+	return chunks
+}
+
+func makeChatDeltaChunk(state *ResponsesEventToChatState, delta ChatDelta) ChatCompletionsChunk {
+	return ChatCompletionsChunk{
+		ID:      state.ID,
+		Object:  "chat.completion.chunk",
+		Created: state.Created,
+		Model:   state.Model,
+		Choices: []ChatChunkChoice{{
+			Index:        0,
+			Delta:        delta,
+			FinishReason: nil,
+		}},
+	}
+}
+
+func makeChatFinishChunk(state *ResponsesEventToChatState, finishReason string) ChatCompletionsChunk {
+	empty := ""
+	return ChatCompletionsChunk{
+		ID:      state.ID,
+		Object:  "chat.completion.chunk",
+		Created: state.Created,
+		Model:   state.Model,
+		Choices: []ChatChunkChoice{{
+			Index:        0,
+			Delta:        ChatDelta{Content: &empty},
+			FinishReason: &finishReason,
+		}},
+	}
+}
+
+// generateChatCmplID returns a "chatcmpl-" prefixed random hex ID.
+func generateChatCmplID() string {
+	b := make([]byte, 12)
+	_, _ = rand.Read(b)
+	return "chatcmpl-" + hex.EncodeToString(b)
+}

backend/internal/pkg/apicompat/types.go

@@ -329,6 +329,148 @@ type ResponsesStreamEvent struct {
 	SequenceNumber int `json:"sequence_number,omitempty"`
 }
 
+// ---------------------------------------------------------------------------
+// OpenAI Chat Completions API types
+// ---------------------------------------------------------------------------
+
+// ChatCompletionsRequest is the request body for POST /v1/chat/completions.
+type ChatCompletionsRequest struct {
+	Model               string             `json:"model"`
+	Messages            []ChatMessage      `json:"messages"`
+	MaxTokens           *int               `json:"max_tokens,omitempty"`
+	MaxCompletionTokens *int               `json:"max_completion_tokens,omitempty"`
+	Temperature         *float64           `json:"temperature,omitempty"`
+	TopP                *float64           `json:"top_p,omitempty"`
+	Stream              bool               `json:"stream,omitempty"`
+	StreamOptions       *ChatStreamOptions `json:"stream_options,omitempty"`
+	Tools               []ChatTool         `json:"tools,omitempty"`
+	ToolChoice          json.RawMessage    `json:"tool_choice,omitempty"`
+	ReasoningEffort     string             `json:"reasoning_effort,omitempty"` // "low" | "medium" | "high"
+	ServiceTier         string             `json:"service_tier,omitempty"`
+	Stop                json.RawMessage    `json:"stop,omitempty"` // string or []string
+
+	// Legacy function calling (deprecated but still supported)
+	Functions    []ChatFunction  `json:"functions,omitempty"`
+	FunctionCall json.RawMessage `json:"function_call,omitempty"`
+}
+
+// ChatStreamOptions configures streaming behavior.
+type ChatStreamOptions struct {
+	IncludeUsage bool `json:"include_usage,omitempty"`
+}
+
+// ChatMessage is a single message in the Chat Completions conversation.
+type ChatMessage struct {
+	Role       string          `json:"role"` // "system" | "user" | "assistant" | "tool" | "function"
+	Content    json.RawMessage `json:"content,omitempty"`
+	Name       string          `json:"name,omitempty"`
+	ToolCalls  []ChatToolCall  `json:"tool_calls,omitempty"`
+	ToolCallID string          `json:"tool_call_id,omitempty"`
+
+	// Legacy function calling
+	FunctionCall *ChatFunctionCall `json:"function_call,omitempty"`
+}
+
+// ChatContentPart is a typed content part in a multi-modal message.
+type ChatContentPart struct {
+	Type     string        `json:"type"` // "text" | "image_url"
+	Text     string        `json:"text,omitempty"`
+	ImageURL *ChatImageURL `json:"image_url,omitempty"`
+}
+
+// ChatImageURL contains the URL for an image content part.
+type ChatImageURL struct {
+	URL    string `json:"url"`
+	Detail string `json:"detail,omitempty"` // "auto" | "low" | "high"
+}
+
+// ChatTool describes a tool available to the model.
+type ChatTool struct {
+	Type     string        `json:"type"` // "function"
+	Function *ChatFunction `json:"function,omitempty"`
+}
+
+// ChatFunction describes a function tool definition.
+type ChatFunction struct {
+	Name        string          `json:"name"`
+	Description string          `json:"description,omitempty"`
+	Parameters  json.RawMessage `json:"parameters,omitempty"`
+	Strict      *bool           `json:"strict,omitempty"`
+}
+
+// ChatToolCall represents a tool call made by the assistant.
+// Index is only populated in streaming chunks (omitted in non-streaming responses).
+type ChatToolCall struct {
+	Index    *int             `json:"index,omitempty"`
+	ID       string           `json:"id,omitempty"`
+	Type     string           `json:"type,omitempty"` // "function"
+	Function ChatFunctionCall `json:"function"`
+}
+
+// ChatFunctionCall contains the function name and arguments.
+type ChatFunctionCall struct {
+	Name      string `json:"name"`
+	Arguments string `json:"arguments"`
+}
+
+// ChatCompletionsResponse is the non-streaming response from POST /v1/chat/completions.
+type ChatCompletionsResponse struct {
+	ID                string       `json:"id"`
+	Object            string       `json:"object"` // "chat.completion"
+	Created           int64        `json:"created"`
+	Model             string       `json:"model"`
+	Choices           []ChatChoice `json:"choices"`
+	Usage             *ChatUsage   `json:"usage,omitempty"`
+	SystemFingerprint string       `json:"system_fingerprint,omitempty"`
+	ServiceTier       string       `json:"service_tier,omitempty"`
+}
+
+// ChatChoice is a single completion choice.
+type ChatChoice struct {
+	Index        int         `json:"index"`
+	Message      ChatMessage `json:"message"`
+	FinishReason string      `json:"finish_reason"` // "stop" | "length" | "tool_calls" | "content_filter"
+}
+
+// ChatUsage holds token counts in Chat Completions format.
+type ChatUsage struct {
+	PromptTokens        int               `json:"prompt_tokens"`
+	CompletionTokens    int               `json:"completion_tokens"`
+	TotalTokens         int               `json:"total_tokens"`
+	PromptTokensDetails *ChatTokenDetails `json:"prompt_tokens_details,omitempty"`
+}
+
+// ChatTokenDetails provides a breakdown of token usage.
+type ChatTokenDetails struct {
+	CachedTokens int `json:"cached_tokens,omitempty"`
+}
+
+// ChatCompletionsChunk is a single streaming chunk from POST /v1/chat/completions.
+type ChatCompletionsChunk struct {
+	ID                string            `json:"id"`
+	Object            string            `json:"object"` // "chat.completion.chunk"
+	Created           int64             `json:"created"`
+	Model             string            `json:"model"`
+	Choices           []ChatChunkChoice `json:"choices"`
+	Usage             *ChatUsage        `json:"usage,omitempty"`
+	SystemFingerprint string            `json:"system_fingerprint,omitempty"`
+	ServiceTier       string            `json:"service_tier,omitempty"`
+}
+
+// ChatChunkChoice is a single choice in a streaming chunk.
+type ChatChunkChoice struct {
+	Index        int       `json:"index"`
+	Delta        ChatDelta `json:"delta"`
+	FinishReason *string   `json:"finish_reason"` // pointer: null when not final
+}
+
+// ChatDelta carries incremental content in a streaming chunk.
+type ChatDelta struct {
+	Role      string         `json:"role,omitempty"`
+	Content   *string        `json:"content,omitempty"` // pointer: omit when not present, null vs "" matters
+	ToolCalls []ChatToolCall `json:"tool_calls,omitempty"`
+}
+
 // ---------------------------------------------------------------------------
 // Shared constants
 // ---------------------------------------------------------------------------

backend/internal/pkg/gemini/models.go

@@ -18,10 +18,12 @@ func DefaultModels() []Model {
 	return []Model{
 		{Name: "models/gemini-2.0-flash", SupportedGenerationMethods: methods},
 		{Name: "models/gemini-2.5-flash", SupportedGenerationMethods: methods},
+		{Name: "models/gemini-2.5-flash-image", SupportedGenerationMethods: methods},
 		{Name: "models/gemini-2.5-pro", SupportedGenerationMethods: methods},
 		{Name: "models/gemini-3-flash-preview", SupportedGenerationMethods: methods},
 		{Name: "models/gemini-3-pro-preview", SupportedGenerationMethods: methods},
 		{Name: "models/gemini-3.1-pro-preview", SupportedGenerationMethods: methods},
+		{Name: "models/gemini-3.1-flash-image", SupportedGenerationMethods: methods},
 	}
 }