fix(saas): SSE 用量统计一致性修复 — 回写 usage_records + 消除 relay_requests 双重计数

- service.rs: SSE 流结束后回写 usage_records 真实 token (status=success)
- service.rs: spawned task 中调用 increment_usage 统一递增 tokens + relay_requests
- handlers.rs: 移除 SSE 路径的 increment_dimension("relay_requests") 消除双重计数
- 从 request_body 提取 model_id 用于 usage_records 精准归因

crates/zclaw-saas/src/relay/handlers.rs

@@ -333,14 +333,8 @@ pub async fn chat_completions(
                 }
             }
 
-            // SSE: relay_requests 实时递增（tokens 由 AggregateUsageWorker 对账修正）
-            if let Err(e) = crate::billing::service::increment_dimension(
-                &state.db, &account_id_usage, "relay_requests",
-            ).await {
-                tracing::warn!("Failed to increment billing relay_requests for {}: {}", account_id_usage, e);
-            }
-
             // SSE 流已返回，递减队列计数器（流式任务开始处理）
+            // 注意: relay_requests 和 tokens 统一由 execute_relay spawned task 中的 increment_usage 递增
             state.cache.relay_dequeue(&account_id_usage);
 
             let response = axum::response::Response::builder()

crates/zclaw-saas/src/relay/service.rs

@@ -333,6 +333,12 @@ pub async fn execute_relay(
                     let task_id_clone = task_id.to_string();
                     let key_id_for_spawn = key_id.clone();
                     let account_id_clone = account_id.to_string();
+                    let provider_id_clone = provider_id.to_string();
+                    // 从 request_body 提取 model_id 用于 usage_records 归因
+                    let model_id_clone = serde_json::from_str::<serde_json::Value>(request_body)
+                        .ok()
+                        .and_then(|v| v.get("model").and_then(|m| m.as_str()).map(String::from))
+                        .unwrap_or_default();
 
                     // Bounded channel for backpressure: 128 chunks (~128KB) buffer.
                     // If the client reads slowly, the upstream is signaled via
@@ -434,16 +440,23 @@ pub async fn execute_relay(
                         let input_opt = if input > 0 { Some(input) } else { None };
                         let output_opt = if output > 0 { Some(output) } else { None };
 
-                        // Record task status + billing usage + key usage
+                        // Record task status + billing usage + key usage + usage_records
                         let db_op = async {
                             if let Err(e) = update_task_status(&db_clone, &task_id_clone, "completed", input_opt, output_opt, None).await {
                                 tracing::warn!("Failed to update task status after SSE stream: {}", e);
                             }
-                            // P2-9 修复: SSE 路径也更新 billing_usage_quotas
+                            // SSE 路径回写 usage_records + billing 配额
                             if input > 0 || output > 0 {
+                                // 回写 usage_records 真实 token（补全 handlers.rs 中 token=0 的占位记录）
+                                if let Err(e) = crate::model_config::service::record_usage(
+                                    &db_clone, &account_id_clone, &provider_id_clone, &model_id_clone,
+                                    input, output, None, "success", None,
+                                ).await {
+                                    tracing::warn!("Failed to record SSE usage for task {}: {}", task_id_clone, e);
+                                }
+                                // 更新 billing_usage_quotas（tokens + relay_requests 同步递增）
                                 if let Err(e) = crate::billing::service::increment_usage(
-                                    &db_clone, &account_id_clone,
+                                    &db_clone, &account_id_clone, input, output,
-                                    input, output,
                                 ).await {
                                     tracing::warn!("Failed to increment billing usage for SSE task {}: {}", task_id_clone, e);
                                 }