fix(restore): restore single file with [ or ] in name on Windows (#1254)

internal/orchestrator/repo/repo.go

@@ -454,9 +454,28 @@ func chunkBy[T any](items []T, chunkSize int) (chunks [][]T) {
 
 var globEscapeReplacer = strings.NewReplacer(`\`, `\\`, `*`, `\*`, `?`, `\?`, `[`, `\[`, `]`, `\]`)
 
+// On Windows, restic's --include uses Go's path/filepath.Match, which treats
+// '\' as a path separator (not an escape character) and rejects the POSIX
+// class self-escape `[[]` / `[]]` as an invalid pattern. There is therefore
+// no way to express a literal '[' or ']' as a match character on Windows.
+//
+// NTFS forbids '*' and '?' in real filenames, so the single-character
+// wildcard '?' is safe to use as a stand-in for '[' and ']' in a leaf-name
+// pattern: it can never collide with a sibling whose name is exactly the
+// requested file. It may, however, match a same-length sibling whose name
+// differs only in the position of the substituted bracket — typically zero,
+// occasionally one or two real-world siblings.
+//
+// Trade-off: the prior behaviour silently restored zero files when the
+// requested leaf had a bracket in its name (matches no snapshot path).
+// With this fix the requested file is restored; same-length siblings may
+// also land in the target dir. A caller that wants exact-set semantics
+// should sweep the target after restore against the requested path list.
+var windowsBracketReplacer = strings.NewReplacer(`[`, `?`, `]`, `?`)
+
 func escapeGlob(s string) string {
 	if runtime.GOOS == "windows" {
-		return s // escaping is not supported on Windows
+		return windowsBracketReplacer.Replace(s)
 	}
 	return globEscapeReplacer.Replace(s)
 }

internal/orchestrator/repo/repo_test.go

@@ -97,10 +97,13 @@ func TestBackup(t *testing.T) {
 func TestRestore(t *testing.T) {
 	t.Parallel()
 
-	// Use a filepath that exercises a few of the glob characters to test escaping
-	messyFilePathToTestGlobs := "test.txt"
-	if runtime.GOOS != "windows" {
-		messyFilePathToTestGlobs = "test*?[].txt"
+	// Use a filepath that exercises a few of the glob characters to test escaping.
+	// On Windows, '*' and '?' are forbidden in filenames, so the messy name only
+	// contains the brackets — '[' and ']' are legal in NTFS and are the chars
+	// the Windows path of escapeGlob has to handle without backslash escape.
+	messyFilePathToTestGlobs := "test*?[].txt"
+	if runtime.GOOS == "windows" {
+		messyFilePathToTestGlobs = "test[brackets].txt"
 	}
 
 	testFile := path.Join(t.TempDir(), messyFilePathToTestGlobs)
@@ -144,10 +147,6 @@ func TestRestore(t *testing.T) {
 	}
 	t.Logf("restore summary: %+v", restoreSummary)
 
-	if runtime.GOOS == "windows" {
-		return
-	}
-
 	if restoreSummary.FilesRestored != 1 {
 		t.Errorf("expected 1 new file, got %d", restoreSummary.FilesRestored)
 	}