feat: add support for parsing loose JSON lists into arrays in tool call parameters

internal/toolcall/toolcalls_array_parse.go

@@ -0,0 +1,164 @@
+package toolcall
+
+import (
+	"encoding/json"
+	"html"
+	"strings"
+)
+
+func parseLooseJSONArrayValue(raw, paramName string) ([]any, bool) {
+	if preservesCDATAStringParameter(paramName) {
+		return nil, false
+	}
+	trimmed := strings.TrimSpace(html.UnescapeString(raw))
+	if trimmed == "" {
+		return nil, false
+	}
+
+	if parsed, ok := parseLooseJSONArrayCandidate(trimmed, paramName); ok {
+		return parsed, true
+	}
+
+	segments, ok := splitTopLevelJSONValues(trimmed)
+	if !ok {
+		return nil, false
+	}
+
+	out := make([]any, 0, len(segments))
+	for _, segment := range segments {
+		parsed, ok := parseLooseArrayElementValue(segment)
+		if !ok {
+			return nil, false
+		}
+		out = append(out, parsed)
+	}
+	return out, true
+}
+
+func parseLooseJSONArrayCandidate(raw, paramName string) ([]any, bool) {
+	parsed, ok := parseLooseArrayElementValue(raw)
+	if !ok {
+		return nil, false
+	}
+	return coerceArrayValue(parsed, paramName)
+}
+
+func parseLooseArrayElementValue(raw string) (any, bool) {
+	trimmed := strings.TrimSpace(html.UnescapeString(raw))
+	if trimmed == "" {
+		return nil, false
+	}
+
+	var parsed any
+	if err := json.Unmarshal([]byte(trimmed), &parsed); err == nil {
+		return parsed, true
+	}
+
+	repairedBackslashes := repairInvalidJSONBackslashes(trimmed)
+	if repairedBackslashes != trimmed {
+		if err := json.Unmarshal([]byte(repairedBackslashes), &parsed); err == nil {
+			return parsed, true
+		}
+	}
+
+	repairedLoose := RepairLooseJSON(trimmed)
+	if repairedLoose != trimmed {
+		if err := json.Unmarshal([]byte(repairedLoose), &parsed); err == nil {
+			return parsed, true
+		}
+	}
+
+	if strings.Contains(trimmed, "<") && strings.Contains(trimmed, ">") {
+		if parsedXML, ok := parseXMLFragmentValue(trimmed); ok {
+			return parsedXML, true
+		}
+	}
+
+	return nil, false
+}
+
+func coerceArrayValue(value any, paramName string) ([]any, bool) {
+	switch x := value.(type) {
+	case []any:
+		return x, true
+	case map[string]any:
+		if len(x) != 1 {
+			return nil, false
+		}
+
+		if items, ok := x["item"]; ok {
+			if arr, ok := coerceArrayValue(items, ""); ok {
+				return arr, true
+			}
+			return []any{items}, true
+		}
+
+		if paramName != "" {
+			if wrapped, ok := x[paramName]; ok {
+				if arr, ok := coerceArrayValue(wrapped, ""); ok {
+					return arr, true
+				}
+			}
+		}
+	}
+	return nil, false
+}
+
+func splitTopLevelJSONValues(raw string) ([]string, bool) {
+	trimmed := strings.TrimSpace(raw)
+	if trimmed == "" {
+		return nil, false
+	}
+
+	values := make([]string, 0, 2)
+	start := 0
+	depth := 0
+	inString := false
+	escaped := false
+
+	for i, r := range trimmed {
+		if inString {
+			if escaped {
+				escaped = false
+				continue
+			}
+			switch r {
+			case '\\':
+				escaped = true
+			case '"':
+				inString = false
+			}
+			continue
+		}
+
+		switch r {
+		case '"':
+			inString = true
+		case '{', '[':
+			depth++
+		case '}', ']':
+			if depth > 0 {
+				depth--
+			}
+		case ',':
+			if depth == 0 {
+				segment := strings.TrimSpace(trimmed[start:i])
+				if segment == "" {
+					return nil, false
+				}
+				values = append(values, segment)
+				start = i + 1
+			}
+		}
+	}
+
+	last := strings.TrimSpace(trimmed[start:])
+	if last == "" {
+		return nil, false
+	}
+	values = append(values, last)
+	if len(values) < 2 {
+		return nil, false
+	}
+	return values, true
+}