diff --git a/internal/api/log_handler.go b/internal/api/log_handler.go
index 6aec9d9..0c0a32a 100644
--- a/internal/api/log_handler.go
+++ b/internal/api/log_handler.go
@@ -616,13 +616,18 @@ type TrafficMetrics struct {
 	TokensOut int64 `json:"tokens_out"`
 }
 
+// ModelMetricsMap is a map from model name to TrafficMetrics.
+// Keys are model names (e.g. "gpt-4", "claude-3-opus") or "other" for aggregated remaining models.
+// Example: {"gpt-4": {"count": 10, "tokens_in": 1000, "tokens_out": 500}, "other": {"count": 3, "tokens_in": 200, "tokens_out": 100}}
+type ModelMetricsMap map[string]TrafficMetrics
+
 // TrafficBucket represents one time bucket with model breakdown
 type TrafficBucket struct {
 	Time      string `json:"time"`
 	Timestamp int64  `json:"timestamp"`
-	// Breakdown contains per-model metrics, keyed by model name (e.g. "gpt-4", "claude-3-opus", "other")
-	Breakdown map[string]TrafficMetrics `json:"breakdown" swaggertype:"object,object" example:"{\"gpt-4\":{\"count\":10,\"tokens_in\":1000,\"tokens_out\":500},\"claude-3-opus\":{\"count\":5,\"tokens_in\":800,\"tokens_out\":400},\"other\":{\"count\":3,\"tokens_in\":200,\"tokens_out\":100}}"`
-	Total     TrafficMetrics            `json:"total"`
+	// Breakdown is a map from model name (e.g. "gpt-4", "claude-3-opus", "other") to its metrics
+	Breakdown ModelMetricsMap `json:"breakdown"`
+	Total     TrafficMetrics  `json:"total"`
 }
 
 // TrafficChartResponse is the response for traffic chart API
@@ -641,7 +646,7 @@ const (
 
 // GetTrafficChart godoc
 // @Summary      Traffic chart data (admin)
-// @Description  Get time × model aggregated data for stacked traffic charts. Returns time buckets with per-model breakdown.
+// @Description  Get time × model aggregated data for stacked traffic charts. Returns time buckets with per-model breakdown. The 'breakdown' field in each bucket is a map where keys are model names (e.g. "gpt-4", "claude-3-opus") and values are TrafficMetrics objects. Models outside top_n are aggregated under the key "other". Example: {"gpt-4": {"count": 10, "tokens_in": 1000, "tokens_out": 500}, "other": {"count": 3, "tokens_in": 200, "tokens_out": 100}}
 // @Tags         admin
 // @Produce      json
 // @Security     AdminAuth