copy-to-slack

name	copy-to-slack
description	Convert markdown to Slack-ready rich text and copy to clipboard.
allowed-tools	Bash, Read
disable-model-invocation	true

Convert a markdown file to rich text and copy it to the clipboard so it can be pasted into Slack with formatting intact.

Input

The user provides either:

• A file path as $ARGUMENTS
• A file path from recent conversation context

Steps

1. Read the markdown file
2. Manually convert the markdown to HTML (do NOT use pandoc or any external tool). Apply these conversions:
   • **bold** → <strong>bold</strong>
   • _italic_ / *italic* → <em>italic</em>
   • `code` → <code>code</code>
   • Fenced code blocks → <pre><code>...</code></pre>
   • - item / * item → <ul><li>item</li></ul>
   • 1. item → <ol><li>item</li></ol>
   • [text](url) → <a href="url">text</a>
   • # Header → <strong>Header</strong> (Slack has no native headers)
   • Paragraph breaks → <br><br> (Slack ignores <p> margins, so use <br><br> between paragraphs for visible spacing)
3. Also prepare a plain-text version (strip markdown syntax)
4. Copy to clipboard with both HTML and plain-text representations. Use >| instead of > for redirects (zsh has noclobber set). Use this snippet:

html_file=$(mktemp)
plain_file=$(mktemp)

printf '%s' "$html" >| "$html_file"
printf '%s' "$plain" >| "$plain_file"

swift -e "
import AppKit
let html = try! String(contentsOfFile: \"$html_file\", encoding: .utf8)
let plain = try! String(contentsOfFile: \"$plain_file\", encoding: .utf8)
let pb = NSPasteboard.general
pb.clearContents()
pb.setString(html, forType: .html)
pb.setString(plain, forType: .string)
"

rm -f "$html_file" "$plain_file"

5. Confirm to the user what was copied

Markdown → Slack formatting mapping

Slack's rich text paste interprets HTML. Key mappings:

• **bold** → <strong> → bold in Slack
• _italic_ → <em> → italic in Slack
• `code` → <code> → inline code in Slack
• Code blocks → <pre><code> → code blocks in Slack
• - item → <ul><li> → bullet lists in Slack
• [text](url) → <a href> → clickable links in Slack
• Headers → bold text (Slack doesn't have native headers)