Slack Message Writer

Write Slack-native messages that are easy to scan, hard to misunderstand, and ready to paste. Copy the final artifact to the clipboard unless the user opts out.

Core Philosophy

1. Lead with the point. Put the decision, request, outcome, or incident state in the first line. Context follows the headline.
2. Design for scanning. Use short paragraphs, meaningful labels, and lists only when they reduce reading time.
3. Match Slack's actual syntax. Composer markup, API mrkdwn, standard Markdown blocks, and rich_text are different formats. Pick one before writing.
4. Notify deliberately. Mention the smallest useful audience. Never introduce @channel, @here, @everyone, or a user-group mention without explicit intent.
5. Deliver, do not merely display. Show the final message, copy those exact bytes to the clipboard, and confirm completion without claiming it was sent.

Workflow

1. Infer the audience, purpose, desired action, deadline, and tone from context.
2. Ask one concise question only when a missing fact materially changes the message.
3. Select a delivery mode from the table below. Default to Clipboard composer.
4. Draft the message with the relevant recipe.
5. Remove throat-clearing, duplicate context, decorative formatting, and vague asks.
6. Check names, links, dates, identifiers, and notification scope. Do not invent any.
7. Display the final message in one fenced text block.
8. Pipe the exact unfenced text to scripts/copy-to-clipboard.sh.
9. Report Copied to clipboard. Do not say sent unless a separate Slack tool sent it.

Delivery Modes

User intent	Output mode	Formatting
Write, draft, reply, announce, copy	Clipboard composer	Slack markup: *bold*, _italic_, ~strike~, code, quotes, Markdown-style links
Build a Web API message using text	API mrkdwn	Slack mrkdwn, `<url
Preserve an LLM's standard Markdown	API Markdown	markdown_text or a markdown block, with standard **bold** and lists
Build a structured app message	API rich layout	Prefer Block Kit rich_text; include accessible top-level fallback text

Do not mix syntaxes. In particular, clipboard output should not contain API-only forms such as <@U123> or <!date...> unless the user explicitly requested an API payload.

Quick-Start: Common Messages

"Ask for action or review"

Use: request first, minimum context, owner or audience, deadline, link.

*Review requested: onboarding copy*
Please review the updated onboarding copy by Thursday at 14:00.

Focus on:
- Whether the value proposition is clear
- Any missing objections

[Open the draft](https://example.com)

"Share a status update"

Use: state, completed, next, risk or blocker. Omit empty sections.

*Project Atlas: on track for Friday*
- *Done:* Import flow and validation
- *Next:* Migration rehearsal
- *Risk:* Final legal copy is due Thursday

"Announce a change"

Use: what changed, who is affected, when, required action, source of truth.

*New expense approval flow starts Monday*
Requests over $1,000 will require Finance approval. Existing requests are unchanged.

*Action:* Use the new form for requests created from Monday onward.
[Read the guide](https://example.com)

"Post an incident update"

Use a stable sequence: status, impact, action underway, next update. Use absolute times with a timezone in clipboard messages; use Slack localized dates for API mode.

*Investigating: delayed report generation*
*Impact:* Reports are completing 20-30 minutes late. No data loss is observed.
*Current action:* We are draining the backed-up worker queue.
*Next update:* 15:30 UTC, or sooner if the status changes.

"Record a decision"

Use: decision, reason, consequence, owner or follow-up.

*Decision: keep the launch behind the existing feature flag*
The rollback path is already proven, and a second flag would add operational risk.

*Follow-up:* Maya will raise the rollout from 10% to 25% after tomorrow's error review.

"Hand off work"

Use: current state, exact next action, known risk, links. Avoid a diary of completed work.

*Handoff: billing migration rehearsal*
The staging migration completed and row counts match.

*Next:* Run the rollback rehearsal with the 2026-09-01 snapshot.
*Watch:* The cleanup step holds a table lock for about 40 seconds.
[Runbook](https://example.com)

Formatting Judgment

Signal	Use	Avoid
One key takeaway	Bold first-line headline	Multiple competing headings
Three or more parallel facts	Bulleted list	Bullets for a single sentence
Commands, IDs, literal values	Inline code or code block	Bold code-like text
Quoted source material	Block quote	Quoting your own summary
One primary action	A labeled action line	Several unlabeled links
Urgent operational change	Explicit impact and next update	Emoji-only urgency
Broad notification	Smallest relevant mention	Unrequested mass mentions

Use at most one or two purposeful emoji when tone benefits. Never use emoji as the only carrier of status, urgency, approval, or failure.

Clipboard Delivery

Send only the final message body over standard input:

bash scripts/copy-to-clipboard.sh <<'SLACK_MESSAGE'
*Final Slack message*
Exact text to copy.
SLACK_MESSAGE

The heredoc adds one final newline; display the same message with that newline. Never copy analysis, alternatives, the surrounding code fence, or the completion note.

Decision Trees

Question	If yes	If no
Did the user request API JSON or Block Kit?	Use API mode and load the reference	Use clipboard composer mode
Is there one explicit action?	Put it in the first two lines	Lead with the outcome or state
Does a mention notify many people?	Require explicit user intent	Use the narrow mention
Is a date viewed across timezones?	Use localized API date syntax in API mode	Include an explicit timezone
Is the message longer than one screen?	Cut detail or link to a document	Keep it self-contained
Is the content sensitive or surprising?	Preserve neutral wording and ask before adding names	Draft directly

Scripts

Script	Usage
scripts/copy-to-clipboard.sh	Copy non-empty UTF-8 text from standard input as literal macOS plain text; rejects missing input, invalid UTF-8, and unsupported arguments

Reference Index

File	Contents
references/slack-formatting.md	Current composer markup, API mrkdwn, standard Markdown blocks, rich text, mentions, dates, escaping, parsing controls, accessibility, limits, and mode-specific checks