matrix-announcement

name	matrix-announcement
description	Use when composing a Matrix announcement — skill release, version bump, weekly digest, breaking-change heads-up, postmortem, RFC, multi-skill pipeline summary, or any agent-authored room post longer than a single line. Defines the HTML subset clients render, the type-tag system, glyph rules (no rockets, no party emoji), the m.text vs m.notice choice, and when to render an HTML card to PNG instead of cramming layout into formatted_body. Trigger before any matrix-send call that produces structured content. Companion to matrix-communication.
license	(MIT AND CC-BY-SA-4.0). See LICENSE-MIT and LICENSE-CC-BY-SA-4.0
compatibility	Pairs with matrix-communication for sending. Optional: headless Chromium for rendering HTML cards to PNG.
metadata	{"author":"Netresearch DTT GmbH","version":"1.24.0","repository":"https://github.com/netresearch/matrix-skill"}
allowed-tools	Bash(chromium:*) Bash(curl:*) Bash(jq:*) Read Write

Matrix Announcement

Content guidance for Matrix announcements; matrix-communication does the sending.

The five rules

1. One headline, one purpose. A Matrix message is a tweet, not a blog post.
2. Send formatted_body with the HTML subset. body stays as plaintext fallback. Never send only Markdown — clients are not required to parse it.
3. Lists beat paragraphs. If you're tempted to write "and also …", start a <ul>.
4. Wrap code. Inline <code> for commands, paths, version strings, IDs, env vars — every one of them. Multi-line snippets in <pre><code class="language-…">.
5. Layout > words → render an HTML card to PNG. Comparisons, dashboards, multi-row tables die in formatted_body.

Type tags (pick one — never stack)

Tag	Meaning	Title example
New skill	first public release	New skill: github-release-skill v0.2.0
Release	feature version	Release: jira-skill v3.12.0
Patch	bugfix-only	Patch: docker-development-skill v1.7.0
Digest	weekly / multi-skill roundup	Digest: skill ecosystem — week of 2026-04-22
Heads-up	breaking change, deprecation	Heads-up: matrix-skill v2 drops Python 3.8
Postmortem	incident summary	Postmortem: CI cache wipe 2026-04-25
RFC	proposal seeking feedback	RFC: unified checkpoint schema

Glyphs

One leading glyph at most. Never trailing decoration, multi-emoji ladders, 🚀, or 🎉. Approved: 🤖 bot · 📦 release · 🔧 tooling · 🛡 security · ⚠️ heads-up · 📋 digest · 🔬 RFC · 🚑 hotfix · 🔥 postmortem · ✨ new capability (sparingly).

Pre-send checklist

• Title fits on one line in Element on a 1280-wide screen.
• First sentence states the change. No "we're excited to".
• Every URL wrapped in <a> with destination-as-text.
• Every command, path, version is in <code>.
• Multi-line code in <pre><code class="language-…">.
• At most one prefix glyph; no trailing emoji; no celebration.
• body is a real readable plaintext fallback, not stripped HTML.
• msgtype = m.notice for unattended automation, m.text otherwise.
• No @room unless it is an outage.
• Layout-heavy → card image with text fallback, not <table> in formatted_body.
• Length under 3000 chars or split into a thread.

References

• html-subset.md — allowed/banned tags, Markdown↔HTML, data-mx-* attributes
• structure.md — skeleton, section patterns, element-when-to-use, length budget, m.text vs m.notice
• glyphs.md — full glyph table with banned set
• image-cards.md — chromium → upload → m.image recipe; image-pairing rules
• threading.md — threads, mentions, edits, redactions
• anti-patterns.md — wall-of-text, emoji ladder, mention storm, inline URLs (with fixes)
• text-templates.md — drop-in formatted_body skeletons per type tag
• templates/ — release-card.html (1200×630), weekly-digest.html (1200×1500), comparison.html (1200×900)
• gallery.html — visual preview of every rule, the five worked examples, and the three templates

Sending: pass the composed message to matrix-communication (matrix-send-e2ee.py "$ROOM" "$MARKDOWN" [--notice]). The transport converts markdown to HTML using the rules in html-subset.md; pass --notice for unattended automation so other bots can't auto-reply (mutually exclusive with --emote). For hand-crafted formatted_body or m.image cards, call the homeserver API directly — recipe in image-cards.md.