feat: log non-200/non-429 kiro errors to rolling file for debugging

Writes request body + response body of failed upstream calls to
kiro_errors.log in the working directory. File is capped at 10MB;
when the next write would exceed that, the file is truncated so
only the most recent records are kept.

Helps diagnose 400 "Improperly formed request" errors where both
CW and Q reject the same payload.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

proxy/error_log.go

@@ -0,0 +1,47 @@
+package proxy
+
+import (
+	"fmt"
+	"os"
+	"sync"
+	"time"
+)
+
+const (
+	kiroErrorLogPath    = "kiro_errors.log"
+	kiroErrorLogMaxSize = 10 * 1024 * 1024 // 10MB, truncate and restart when exceeded
+)
+
+var kiroErrorLogMu sync.Mutex
+
+// logKiroError appends a non-200/non-429 failure record to kiro_errors.log in the
+// current working directory. The file is capped at 10MB; when the next write would
+// push it over the limit, the file is truncated so only the most recent records
+// are retained.
+func logKiroError(reqID, endpoint string, status int, account, model string, reqBody, respBody []byte) {
+	kiroErrorLogMu.Lock()
+	defer kiroErrorLogMu.Unlock()
+
+	entry := fmt.Sprintf(
+		"===== %s  req=%s  endpoint=%s  status=%d  account=%s  model=%s =====\n"+
+			"-- request body --\n%s\n"+
+			"-- response body --\n%s\n\n",
+		time.Now().Format("2006-01-02 15:04:05"),
+		reqID, endpoint, status, account, model,
+		string(reqBody), string(respBody),
+	)
+
+	// If the next entry would exceed the cap, truncate the file first.
+	if info, err := os.Stat(kiroErrorLogPath); err == nil {
+		if info.Size()+int64(len(entry)) > kiroErrorLogMaxSize {
+			_ = os.Truncate(kiroErrorLogPath, 0)
+		}
+	}
+
+	f, err := os.OpenFile(kiroErrorLogPath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
+	if err != nil {
+		return
+	}
+	defer f.Close()
+	_, _ = f.WriteString(entry)
+}

proxy/kiro.go

@@ -285,6 +285,11 @@ func CallKiroAPI(account *config.Account, payload *KiroPayload, callback *KiroSt
 				lastStatus = fmt.Sprintf("%d", resp.StatusCode)
 				bodyStr := string(errBody)
 
+				// 记录非 200 / 非 429 的请求体和响应体以便排查（本地滚动日志，上限 10MB）
+				if resp.StatusCode != 429 {
+					logKiroError(reqID, ep.Name, resp.StatusCode, accountLabel, modelID, reqBody, errBody)
+				}
+
 				if resp.StatusCode == 401 || resp.StatusCode == 403 {
 					log.Printf("[KiroAPI] %d  %s  %s/a%d  auth_error  %s  %s", resp.StatusCode, reqID, epShort, attempt, fmtMs(time.Since(attemptStart)), truncateForLog(bodyStr, 200))
 					log.Printf("[KiroAPI] FAIL %s  all endpoints failed  %s  last=%s", reqID, fmtMs(time.Since(requestStart)), lastStatus)