feat(edit): add markdown file support with tailored prompt

- Introduce check for .md extension and use technical writer system prompt.
- Adjust response cleaning: trim for markdown, use CleanCodeResponse for code.
- Remove nolint comment and unnecessary line skipping in removeLastModifiedComments.

cmd/edit.go

@@ -35,7 +35,6 @@ var editCmd = &cobra.Command{
 			os.Exit(1)
 		}
 
-		// nolint:gosec // intentional file read from user input
 		original, err := os.ReadFile(filePath)
 		if err != nil {
 			logger.Error("failed to read file", "file", filePath, "error", err)
@@ -46,14 +45,28 @@ var editCmd = &cobra.Command{
 		cleanedOriginal := removeLastModifiedComments(string(original))
 
 		client := grok.NewClient()
-		messages := []map[string]string{
+		isMarkdown := filepath.Ext(filePath) == ".md"
-			{"role": "system", "content": "You are an expert programmer. Remove all unnecessary comments including last modified timestamps and ownership comments. Return only the cleaned code with no explanations, no markdown, no extra text."},
+		var messages []map[string]string
-			{"role": "user", "content": fmt.Sprintf("File: %s\n\nOriginal content:\n%s\n\nTask: %s", filepath.Base(filePath), cleanedOriginal, instruction)},
+		if isMarkdown {
+			messages = []map[string]string{
+				{"role": "system", "content": "You are an expert technical writer. Edit markdown content clearly and concisely. Return only the edited markdown with no explanations, no markdown formatting, no extra text."},
+				{"role": "user", "content": fmt.Sprintf("File: %s\n\nOriginal content:\n%s\n\nTask: %s", filepath.Base(filePath), cleanedOriginal, instruction)},
+			}
+		} else {
+			messages = []map[string]string{
+				{"role": "system", "content": "You are an expert programmer. Remove all unnecessary comments including last modified timestamps and ownership comments. Return only the cleaned code with no explanations, no markdown, no extra text."},
+				{"role": "user", "content": fmt.Sprintf("File: %s\n\nOriginal content:\n%s\n\nTask: %s", filepath.Base(filePath), cleanedOriginal, instruction)},
+			}
 		}
 
 		color.Yellow("Asking Grok to %s...\n", instruction)
 		raw := client.StreamSilent(messages, model)
-		newContent := grok.CleanCodeResponse(raw)
+		var newContent string
+		if isMarkdown {
+			newContent = strings.TrimSpace(raw)
+		} else {
+			newContent = grok.CleanCodeResponse(raw)
+		}
 		color.Green("✓ Response received")
 
 		color.Cyan("\nProposed changes:")
@@ -92,9 +105,6 @@ func removeLastModifiedComments(content string) string {
 	cleanedLines := make([]string, 0, len(lines))
 
 	for _, line := range lines {
-		if strings.Contains(line, "Last modified") {
-			continue
-		}
 		cleanedLines = append(cleanedLines, line)
 	}