chore: import upstream snapshot with attribution

shortcuts/markdown/markdown_errors.go

@@ -0,0 +1,53 @@
+// Copyright (c) 2026 Lark Technologies Pte. Ltd.
+// SPDX-License-Identifier: MIT
+
+package markdown
+
+import (
+	"errors"
+
+	"github.com/larksuite/cli/errs"
+)
+
+func markdownValidationError(format string, args ...any) *errs.ValidationError {
+	return errs.NewValidationError(errs.SubtypeInvalidArgument, format, args...)
+}
+
+func markdownValidationParamError(param, format string, args ...any) *errs.ValidationError {
+	return markdownValidationError(format, args...).WithParam(param)
+}
+
+func markdownInvalidParam(name, reason string) errs.InvalidParam {
+	return errs.InvalidParam{Name: name, Reason: reason}
+}
+
+// withMarkdownFileParam tags a validation failure with the originating flag
+// when it does not already name one. Shared input-file helpers such as
+// common.WrapInputStatErrorTyped cannot know which flag supplied the path, so
+// the caller attaches it here to keep the recoverable param on the wire.
+func withMarkdownFileParam(err error, param string) error {
+	if err == nil || param == "" {
+		return err
+	}
+	var ve *errs.ValidationError
+	if errors.As(err, &ve) && ve.Param == "" {
+		ve.WithParam(param)
+	}
+	return err
+}
+
+// wrapMarkdownDownloadError classifies a download failure. An already-typed
+// error keeps its carrier — type, subtype, code and extensions — so callers see
+// the upstream classification: a validation problem passes through verbatim,
+// any other problem gains a "download failed" prefix for operation context.
+// An untyped error becomes a network transport error carrying the original as
+// its cause.
+func wrapMarkdownDownloadError(err error) error {
+	if p, ok := errs.ProblemOf(err); ok {
+		if p.Category != errs.CategoryValidation {
+			p.Message = "download failed: " + p.Message
+		}
+		return err
+	}
+	return errs.NewNetworkError(errs.SubtypeNetworkTransport, "download failed: %s", err).WithCause(err)
+}