Implement artifact-level render command with Markdown output and update docs

internal/render/markdown.go

@@ -0,0 +1,75 @@
+package render
+
+import (
+	"fmt"
+	"math"
+	"strings"
+)
+
+// MarkdownRenderer renders transcript artifacts as Markdown.
+type MarkdownRenderer struct{}
+
+// Render renders the transcript into deterministic Markdown.
+func (MarkdownRenderer) Render(transcript Transcript, opts Options) (string, error) {
+	var lines []string
+
+	title := strings.TrimSpace(opts.Title)
+	if title == "" {
+		title = "Transcript"
+	}
+	lines = append(lines, "# "+title, "")
+
+	if opts.IncludeMetadata {
+		lines = append(lines,
+			fmt.Sprintf("- Application: %s", transcript.Metadata.Application),
+			fmt.Sprintf("- Version: %s", transcript.Metadata.Version),
+			fmt.Sprintf("- Output schema: %s", transcript.Schema),
+			"",
+		)
+	}
+
+	for _, segment := range transcript.Segments {
+		parts := make([]string, 0, 4)
+		if opts.IncludeTimestamps {
+			parts = append(parts, fmt.Sprintf("[%s–%s]", formatTimestamp(segment.Start), formatTimestamp(segment.End)))
+		}
+		if opts.IncludeSegmentIDs {
+			parts = append(parts, fmt.Sprintf("[#%d]", segment.ID))
+		}
+
+		text := segment.Text
+		if shouldItalicize(segment.Categories) {
+			text = "*" + text + "*"
+		}
+		parts = append(parts, fmt.Sprintf("**%s:** %s", segment.Speaker, text))
+		lines = append(lines, strings.Join(parts, " "))
+		lines = append(lines, "")
+	}
+
+	output := strings.Join(lines, "\n")
+	if !strings.HasSuffix(output, "\n") {
+		output += "\n"
+	}
+	return output, nil
+}
+
+func shouldItalicize(categories []string) bool {
+	for _, category := range categories {
+		switch category {
+		case "background", "backchannel", "filler":
+			return true
+		}
+	}
+	return false
+}
+
+func formatTimestamp(seconds float64) string {
+	total := int(math.Round(seconds))
+	if total < 0 {
+		total = 0
+	}
+	hours := total / 3600
+	minutes := (total % 3600) / 60
+	remainder := total % 60
+	return fmt.Sprintf("%02d:%02d:%02d", hours, minutes, remainder)
+}