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backend/internal/translator/common/request.go

@@ -0,0 +1,61 @@
+package common
+
+import (
+	"crypto/rand"
+	"strings"
+
+	"github.com/tidwall/gjson"
+)
+
+const tooluLetters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
+
+// GenerateClaudeToolCallID generates a random tool use ID prefixed with toolu_
+// using rejection sampling to guarantee a uniform distribution across the 62 alphanumeric characters.
+func GenerateClaudeToolCallID() string {
+	const maxValidByte = 256 - (256 % len(tooluLetters)) // 248: exact multiple of 62
+	var b strings.Builder
+	b.Grow(len("toolu_") + 24)
+	b.WriteString("toolu_")
+
+	var buf [32]byte
+	n := 0
+	for n < 24 {
+		_, _ = rand.Read(buf[:])
+		for _, bVal := range buf {
+			if int(bVal) < maxValidByte {
+				b.WriteByte(tooluLetters[int(bVal)%len(tooluLetters)])
+				n++
+				if n == 24 {
+					break
+				}
+			}
+		}
+	}
+	return b.String()
+}
+
+// RequestModelName returns the model name from the original request, falling
+// back to the translated request when the original request is unavailable.
+func RequestModelName(originalRequestRawJSON, requestRawJSON []byte) string {
+	for _, rawJSON := range [][]byte{originalRequestRawJSON, requestRawJSON} {
+		if modelName := requestModelName(rawJSON); modelName != "" {
+			return modelName
+		}
+	}
+	return ""
+}
+
+func requestModelName(rawJSON []byte) string {
+	if len(rawJSON) == 0 || !gjson.ValidBytes(rawJSON) {
+		return ""
+	}
+
+	root := gjson.ParseBytes(rawJSON)
+	for _, path := range []string{"model", "request.model"} {
+		model := root.Get(path)
+		if model.Type == gjson.String && strings.TrimSpace(model.String()) != "" {
+			return model.String()
+		}
+	}
+	return ""
+}