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backend/examples/plugin/claude-web-search-router/go/detect.go

@@ -0,0 +1,183 @@
+package main
+
+import (
+	"strings"
+
+	"github.com/tidwall/gjson"
+)
+
+const (
+	claudeWebSearchToolTypeA = "web_search_20250305"
+	claudeWebSearchToolTypeB = "web_search_20260209"
+)
+
+// isClaudeSourceFormat reports whether the inbound protocol is Claude / Anthropic Messages.
+func isClaudeSourceFormat(source string) bool {
+	switch strings.ToLower(strings.TrimSpace(source)) {
+	case "claude", "anthropic":
+		return true
+	default:
+		return false
+	}
+}
+
+func isClaudeTypedWebSearchToolType(toolType string) bool {
+	return toolType == claudeWebSearchToolTypeA || toolType == claudeWebSearchToolTypeB
+}
+
+func hasClaudeTypedWebSearchTool(body []byte) bool {
+	tools := gjson.GetBytes(body, "tools")
+	if !tools.IsArray() {
+		return false
+	}
+	for _, tool := range tools.Array() {
+		if isClaudeTypedWebSearchToolType(tool.Get("type").String()) {
+			return true
+		}
+	}
+	return false
+}
+
+func hasOnlyClaudeTypedWebSearchTools(body []byte) bool {
+	tools := gjson.GetBytes(body, "tools")
+	if !tools.IsArray() {
+		return false
+	}
+	hasWebSearch := false
+	for _, tool := range tools.Array() {
+		if isClaudeTypedWebSearchToolType(tool.Get("type").String()) {
+			hasWebSearch = true
+			continue
+		}
+		if tool.Get("type").String() != "" || tool.Get("name").String() != "" {
+			return false
+		}
+	}
+	return hasWebSearch
+}
+
+func looksLikeClaudeCodeWebSearchAssistant(body []byte) bool {
+	system := gjson.GetBytes(body, "system")
+	if system.IsArray() {
+		for _, block := range system.Array() {
+			text := strings.ToLower(block.Get("text").String())
+			if strings.Contains(text, "web search tool use") ||
+				strings.Contains(text, "performing a web search") {
+				return true
+			}
+		}
+	}
+	if system.Type == gjson.String {
+		text := strings.ToLower(system.String())
+		if strings.Contains(text, "web search tool use") {
+			return true
+		}
+	}
+	messages := gjson.GetBytes(body, "messages")
+	if !messages.IsArray() {
+		return false
+	}
+	for _, message := range messages.Array() {
+		if message.Get("role").String() != "user" {
+			continue
+		}
+		text := strings.ToLower(extractClaudeMessageText(message.Get("content")))
+		if strings.HasPrefix(text, "perform a web search for the query:") {
+			return true
+		}
+	}
+	return false
+}
+
+func isClaudeCodeBuiltinWebSearchRequest(body []byte, requireWebSearchOnly bool) bool {
+	if !hasClaudeTypedWebSearchTool(body) {
+		return false
+	}
+	if requireWebSearchOnly && !hasOnlyClaudeTypedWebSearchTools(body) {
+		return false
+	}
+	return looksLikeClaudeCodeWebSearchAssistant(body) || hasOnlyClaudeTypedWebSearchTools(body)
+}
+
+func extractClaudeWebSearchQuery(body []byte) string {
+	if q := extractQueryFromPerformPrefix(body); q != "" {
+		return q
+	}
+	return extractQueryFromUserMessages(body)
+}
+
+func extractQueryFromPerformPrefix(body []byte) string {
+	messages := gjson.GetBytes(body, "messages")
+	if !messages.IsArray() {
+		return ""
+	}
+	const prefix = "perform a web search for the query:"
+	for _, message := range messages.Array() {
+		if message.Get("role").String() != "user" {
+			continue
+		}
+		text := strings.TrimSpace(extractClaudeMessageText(message.Get("content")))
+		lower := strings.ToLower(text)
+		if strings.HasPrefix(lower, prefix) {
+			return strings.TrimSpace(text[len(prefix):])
+		}
+	}
+	return ""
+}
+
+func extractQueryFromUserMessages(body []byte) string {
+	messages := gjson.GetBytes(body, "messages")
+	if !messages.IsArray() {
+		return ""
+	}
+	arr := messages.Array()
+	for i := len(arr) - 1; i >= 0; i-- {
+		message := arr[i]
+		role := message.Get("role").String()
+		if role != "" && role != "user" {
+			continue
+		}
+		if query := strings.TrimSpace(extractClaudeMessageText(message.Get("content"))); query != "" {
+			return query
+		}
+	}
+	return ""
+}
+
+func extractClaudeMessageText(content gjson.Result) string {
+	if content.Type == gjson.String {
+		return content.String()
+	}
+	if !content.IsArray() {
+		return ""
+	}
+	var parts []string
+	for _, block := range content.Array() {
+		if block.Get("type").String() != "text" {
+			continue
+		}
+		if text := strings.TrimSpace(block.Get("text").String()); text != "" {
+			parts = append(parts, text)
+		}
+	}
+	return strings.Join(parts, "\n")
+}
+
+func extractClaudeWebSearchMaxUses(body []byte, defaultMax int) int {
+	if defaultMax <= 0 {
+		defaultMax = 5
+	}
+	tools := gjson.GetBytes(body, "tools")
+	if !tools.IsArray() {
+		return defaultMax
+	}
+	for _, tool := range tools.Array() {
+		if !isClaudeTypedWebSearchToolType(tool.Get("type").String()) {
+			continue
+		}
+		if maxUses := int(tool.Get("max_uses").Int()); maxUses > 0 {
+			return maxUses
+		}
+	}
+	return defaultMax
+}