slack-post-from-context

name

slack-post-from-context

description

Use when the user asks to draft, share, or post something to Slack about the current conversation — phrasings like "post this to slack", "make a slack message about this", "share this on slack", "slack-format this", "draft a slack update". Composes the message in the *paste-into-composer* dialect of Slack formatting (single-asterisk bold, bare URLs, no headings, `:emoji:`) and pipes it to `pbcopy` so the user pastes it directly. macOS only.

Slack post from current context

When the user wants to share what just happened in this conversation as a Slack message, draft it in the format the Slack composer accepts on paste and put it on the clipboard with pbcopy. The clipboard is the deliverable — the user pastes the message into Slack themselves.

Two dialects: paste vs. API — this skill is paste

Slack has two formatting dialects, and the rules differ:

• API mrkdwn (used by the Slack API, MCP tools, webhooks): supports <url|text> links, <@U123> mentions, <#C123|name> channels.
• Composer paste (what pbcopy + ⌘V hits): the WYSIWYG composer partially parses mrkdwn — *bold*, _italic_, ~strike~, backticks, :emoji:, > quotes, and bullets all work. But it does not parse <url|text>; it treats the whole thing as one URL and percent-encodes the | to %7C, breaking the link.

This skill targets the paste dialect. If the user wants the message actually sent (not drafted), use the Slack MCP and the API dialect there.

Formatting cheat-sheet (paste dialect)

Want	Regular markdown	Paste-into-Slack
Bold	**bold**	*bold*
Italic	*italic*	_italic_
Strikethrough	~~text~~	~text~
Inline code	`code`	`code`
Code block	lang ```	``` (no language tag)
Link	[text](url)	bare URL on its own (Slack auto-linkifies; display = URL)
Heading	# Heading	none — bold the line: *Heading*
Bullet	- item	• item (renders nicer than -)
Numbered	1. item	1. item
Quote	> text	> text
User mention	n/a	@name (autocomplete on send turns it into a real ping)
Channel	n/a	#channel (same — autocomplete)
Emoji	n/a	:rocket: :white_check_mark: :warning:

The three that bite hardest:

• **bold** renders as the literal characters **bold**. Use *bold*.
• <url|text> is API format — when pasted into the composer, the | becomes %7C and the link breaks. Paste a bare URL; Slack auto-linkifies it. Custom display text via [text](url) only works for recipients who have "Format messages with markup" enabled — don't rely on it.
• # Heading renders as a literal #. Bold the line instead.

Composing the message

Read the conversation. Pick out:

1. The headline — what was achieved, decided, broken, or shipped. One line, bolded. Lead with it.
2. Concrete artifacts — file paths, PR/ticket numbers, commands, URLs, numbers. Bullet them.
3. Anything the audience needs to act on or react to — questions, blockers, asks. Call them out (:warning: or :question: helps).

Keep it tight. Slack messages over ~10 lines lose readers; condense. Strip narrative ("First I tried X, then Y…") — Slack wants the result.

Putting it on the clipboard

Use a heredoc with single-quoted 'EOF' so $variables, backticks, and backslashes pass through verbatim:

pbcopy <<'EOF'
*Shipped: KGM-3330 banner mismatch fix*

• Root cause: home carousel banner cached past TTL on app cold start
• PR: https://github.com/org/repo/pull/4711
• Verified on iOS 18.7.2 (iPhone 12 Pro Max) and Android 14 (Pixel 5a)
• cc @felix — please review before mobile release cut on 2026-05-01
EOF

Note the bare URL on its own — <url|PR #4711> would paste as a broken URL with %7C in it.

After running, reply to the user with one short line:

Copied — paste into Slack.

Do not also dump the message body into the chat reply. The user will read it when they paste; echoing it just makes them read it twice.

When NOT to use this skill

• The user wants the message posted (not drafted) — that's the Slack MCP (slack_send_message / slack_send_message_draft), not pbcopy
• They want an email, PR description, commit message, or doc — different format
• Non-macOS shell — pbcopy is macOS-only. On Linux use xclip -selection clipboard or wl-copy; on Windows, clip.exe. If you detect a non-mac platform, tell the user and skip the copy step

Common mistakes

Mistake	Fix
**bold**	Slack shows literal **. Use *bold*.
# Heading	Renders as #. Bold the line instead: *Heading*.
<url|text> in pasted text	API mrkdwn, not composer-paste — the | becomes %7C and the link breaks. Paste a bare URL; Slack auto-linkifies.
[text](url) to get custom display text	Only works for recipients with "Format messages with markup" enabled — unreliable. Use a bare URL.
Triple-backtick with language tag	Slack ignores the tag and shows it as code. Drop the language.
Echo the message body in the chat after pbcopy	The clipboard is the deliverable; don't make the user re-read it.
Use echo "…" | pbcopy for multi-line	Quoting breaks on *, backticks, <>. Use a 'EOF'-quoted heredoc.
Pipe markdown straight from a tool	Convert it to paste-format first. Don't copy-paste GitHub-style markdown.