# harden: use filepath.VolumeName in the session-ID volume check

`78cf859`·  
  
Soph·1mo ago·2 files·+7 added/-4 removed

Per PR review (pjbgf): adopt the idiomatic filepath.VolumeName check for Windows volume references. Kept alongside the explicit ":" check because VolumeName is a no-op off Windows — the "C:foo" regression test would not exercise it on a non-Windows CI host, and the ":" form should be rejected on every platform regardless.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

## Sessions

6aa0a864cb61View transcript

## Changes

2

- cmd/entire/cli/validation
  
  - Mvalidators.go+6/-3
  
  - Mvalidators_test.go+1/-1

```
28 unmodified lines

29
30
31
32
32
33
34
35
36
37
36
37
38
39
40
41
42
43

28 unmodified lines

if id == "." || id == ".." {
		return fmt.Errorf("invalid session ID %q: reserved path segment", id)
	}
	// Reject the Windows volume separator. A drive-relative path like "C:foo" is
	// Reject Windows volume references. A drive-relative path like "C:foo" is
	// separator-free and filepath.IsAbs reports it as non-absolute, yet
	// filepath.Join discards the base directory when the appended element
	// carries a volume name — escaping the intended directory on Windows.
	if strings.Contains(id, ":") {
		return fmt.Errorf("invalid session ID %q: contains volume separator", id)
	// filepath.VolumeName is the idiomatic check but is a no-op off Windows, so
	// also reject the ":" form directly for cross-platform coverage (and so the
	// regression test is meaningful on a non-Windows CI host).
	if filepath.VolumeName(id) != "" || strings.Contains(id, ":") {
		return fmt.Errorf("invalid session ID %q: contains volume reference", id)
	}
	// Reject glob metacharacters. Session IDs are interpolated into
	// filepath.Glob patterns in several places (agent transcript lookup,
```

Mcmd/entire/cli/validation/validators.go+6/-3

```
94 unmodified lines

95
96
97
98
98
99
100
101

94 unmodified lines

name:      "windows drive-relative path",
		sessionID: "C:foo",
		wantErr:   true,
		errMsg:    "volume separator",
		errMsg:    "volume reference",
	},
	// Glob metacharacters (would match unrelated files when used in a pattern)
	{