fix: route result output through Config.Output, not os.Stdout

mark.Run and ProcessFile were writing directly to os.Stdout via
fmt.Println, which is a surprising side-effect for library callers.

Add Config.Output io.Writer for callers to provide their own sink.
When nil the helper falls back to io.Discard, so library embedders
that do not set Output receive no implicit stdout writes. The CLI
layer sets Output: os.Stdout to preserve existing behaviour.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

mark.go

@@ -5,6 +5,7 @@ import (
 	"crypto/sha1"
 	"encoding/hex"
 	"fmt"
+	"io"
 	"os"
 	"path/filepath"
 	"regexp"
@@ -67,6 +68,20 @@ type Config struct {
 	Features        []string
 	ImageAlign      string
 	IncludePath     string
+
+	// Output is the writer used for result output (e.g. published page URLs,
+	// compiled HTML). If nil, output is discarded; the CLI sets this to
+	// os.Stdout.
+	Output io.Writer
+}
+
+// output returns the configured writer, falling back to io.Discard so that
+// library callers that do not set Output receive no implicit stdout writes.
+func (c Config) output() io.Writer {
+	if c.Output != nil {
+		return c.Output
+	}
+	return io.Discard
 }
 
 // Run processes all files matching Config.Files and publishes them to Confluence.
@@ -101,7 +116,7 @@ func Run(config Config) error {
 
 		if target != nil {
 			log.Infof(nil, "page successfully updated: %s", config.BaseURL+target.Links.Full)
-			fmt.Println(config.BaseURL + target.Links.Full)
+			fmt.Fprintln(config.output(), config.BaseURL+target.Links.Full)
 		}
 	}
 
@@ -243,7 +258,7 @@ func ProcessFile(file string, api *confluence.API, config Config) (*confluence.P
 			ImageAlign:    imageAlign,
 		}
 		html, _ := markmd.CompileMarkdown(markdown, std, file, cfg)
-		fmt.Println(html)
+		fmt.Fprintln(config.output(), html)
 		return nil, nil
 	}
 

util/cli.go

@@ -83,6 +83,8 @@ func RunMark(ctx context.Context, cmd *cli.Command) error {
 		Features:        cmd.StringSlice("features"),
 		ImageAlign:      cmd.String("image-align"),
 		IncludePath:     cmd.String("include-path"),
+
+		Output: os.Stdout,
 	}
 
 	return mark.Run(config)