tool_args.go RawHistoryFolder

1package provider
2
3import (
4	"encoding/json"
5	"strings"
6)
7
8// normalizeToolArgs turns streamed tool-call arguments into valid JSON.
9// Models sometimes emit raw control characters (tabs, newlines) inside JSON
10// strings; those are escaped so the call keeps its intended arguments.
11// Empty or otherwise unrepairable input becomes "{}" so the message can
12// always be serialized to transcripts and sent back to the provider.
13func normalizeToolArgs(raw string) json.RawMessage {
14	if raw == "" {
15		return json.RawMessage("{}")
16	}
17	if json.Valid([]byte(raw)) {
18		return json.RawMessage(raw)
19	}
20	if repaired := escapeControlCharsInStrings(raw); json.Valid([]byte(repaired)) {
21		return json.RawMessage(repaired)
22	}
23	return json.RawMessage("{}")
24}
25
26// escapeControlCharsInStrings escapes raw U+0000–U+001F bytes that appear
27// inside JSON string literals. Bytes outside strings are left untouched.
28func escapeControlCharsInStrings(raw string) string {
29	const hex = "0123456789abcdef"
30	var b strings.Builder
31	b.Grow(len(raw) + 8)
32	inString, escaped := false, false
33	for i := 0; i < len(raw); i++ {
34		c := raw[i]
35		if !inString {
36			if c == '"' {
37				inString = true
38			}
39			b.WriteByte(c)
40			continue
41		}
42		switch {
43		case escaped:
44			escaped = false
45			b.WriteByte(c)
46		case c == '\\':
47			escaped = true
48			b.WriteByte(c)
49		case c == '"':
50			inString = false
51			b.WriteByte(c)
52		case c == '\t':
53			b.WriteString(`\t`)
54		case c == '\n':
55			b.WriteString(`\n`)
56		case c == '\r':
57			b.WriteString(`\r`)
58		case c < 0x20:
59			b.WriteString(`\u00`)
60			b.WriteByte(hex[c>>4])
61			b.WriteByte(hex[c&0xf])
62		default:
63			b.WriteByte(c)
64		}
65	}
66	return b.String()
67}