feat: add opt-in experimental Claude cch signing

internal/runtime/executor/claude_signing.go

@@ -0,0 +1,64 @@
+package executor
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+
+	xxHash64 "github.com/pierrec/xxHash/xxHash64"
+	"github.com/router-for-me/CLIProxyAPI/v6/internal/config"
+	cliproxyauth "github.com/router-for-me/CLIProxyAPI/v6/sdk/cliproxy/auth"
+)
+
+const claudeCCHSeed uint64 = 0x6E52736AC806831E
+
+var claudeBillingHeaderPlaceholderPattern = regexp.MustCompile(`(x-anthropic-billing-header:[^"]*?\bcch=)(00000)(;)`)
+
+func signAnthropicMessagesBody(body []byte) []byte {
+	if !claudeBillingHeaderPlaceholderPattern.Match(body) {
+		return body
+	}
+
+	cch := fmt.Sprintf("%05x", xxHash64.Checksum(body, claudeCCHSeed)&0xFFFFF)
+	return claudeBillingHeaderPlaceholderPattern.ReplaceAll(body, []byte("${1}"+cch+"${3}"))
+}
+
+func resolveClaudeKeyConfig(cfg *config.Config, auth *cliproxyauth.Auth) *config.ClaudeKey {
+	if cfg == nil || auth == nil {
+		return nil
+	}
+
+	apiKey, baseURL := claudeCreds(auth)
+	if apiKey == "" {
+		return nil
+	}
+
+	for i := range cfg.ClaudeKey {
+		entry := &cfg.ClaudeKey[i]
+		cfgKey := strings.TrimSpace(entry.APIKey)
+		cfgBase := strings.TrimSpace(entry.BaseURL)
+		if !strings.EqualFold(cfgKey, apiKey) {
+			continue
+		}
+		if baseURL != "" && cfgBase != "" && !strings.EqualFold(cfgBase, baseURL) {
+			continue
+		}
+		return entry
+	}
+
+	return nil
+}
+
+// resolveClaudeKeyCloakConfig finds the matching ClaudeKey config and returns its CloakConfig.
+func resolveClaudeKeyCloakConfig(cfg *config.Config, auth *cliproxyauth.Auth) *config.CloakConfig {
+	entry := resolveClaudeKeyConfig(cfg, auth)
+	if entry == nil {
+		return nil
+	}
+	return entry.Cloak
+}
+
+func experimentalCCHSigningEnabled(cfg *config.Config, auth *cliproxyauth.Auth) bool {
+	entry := resolveClaudeKeyConfig(cfg, auth)
+	return entry != nil && entry.ExperimentalCCHSigning
+}