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backend/internal/util/claude_tool_id.go

@@ -0,0 +1,68 @@
+package util
+
+import (
+	"crypto/sha256"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"regexp"
+	"strings"
+	"sync/atomic"
+	"time"
+)
+
+const geminiClaudeToolUseIDPrefix = "cpa_gemini_"
+
+var (
+	claudeToolUseIDSanitizer = regexp.MustCompile(`[^a-zA-Z0-9_-]`)
+	claudeToolUseIDCounter   uint64
+)
+
+// SanitizeClaudeToolID ensures the given id conforms to Claude's
+// tool_use.id regex ^[a-zA-Z0-9_-]+$.  Non-conforming characters are
+// replaced with '_'; an empty result gets a generated fallback.
+func SanitizeClaudeToolID(id string) string {
+	s := claudeToolUseIDSanitizer.ReplaceAllString(id, "_")
+	if s == "" {
+		s = fmt.Sprintf("toolu_%d_%d", time.Now().UnixNano(), atomic.AddUint64(&claudeToolUseIDCounter, 1))
+	}
+	return s
+}
+
+// GeminiClaudeToolUseID returns a stable Claude-facing ID for a provider-native
+// Gemini function call. The opaque ID lets the executor recover the exact
+// provider call from its replay ledger instead of trusting client-mutated args.
+func GeminiClaudeToolUseID(callID, name, argsRaw string) string {
+	callID = strings.TrimSpace(callID)
+	name = strings.TrimSpace(name)
+	if callID == "" || name == "" {
+		return ""
+	}
+	if strings.TrimSpace(argsRaw) != "" {
+		var value any
+		if json.Unmarshal([]byte(argsRaw), &value) == nil {
+			if canonical, errMarshal := json.Marshal(value); errMarshal == nil {
+				argsRaw = string(canonical)
+			}
+		} else {
+			argsRaw = strings.TrimSpace(argsRaw)
+		}
+	}
+	sum := sha256.Sum256([]byte(strings.Join([]string{callID, name, argsRaw}, "\x00")))
+	return geminiClaudeToolUseIDPrefix + hex.EncodeToString(sum[:16])
+}
+
+// IsGeminiClaudeToolUseID reports whether id belongs to the reserved
+// Claude-facing Gemini provenance namespace.
+func IsGeminiClaudeToolUseID(id string) bool {
+	id = strings.TrimSpace(id)
+	if !strings.HasPrefix(id, geminiClaudeToolUseIDPrefix) {
+		return false
+	}
+	digest := strings.TrimPrefix(id, geminiClaudeToolUseIDPrefix)
+	if len(digest) != 32 {
+		return false
+	}
+	_, errDecode := hex.DecodeString(digest)
+	return errDecode == nil
+}