Arialine
Project status: In progressA Slack-native AI diagramming app that turns plain-language messages into Mermaid diagrams, posts interactive HTML and PNG artifacts, and keeps them current as the thread evolves. Every edit becomes a version, every decision stays traceable to the source conversation, and an MCP server lets Slack AI create, edit, explain, and branch diagrams without leaving Slack.
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Arialine started with a simple request: a beautiful Mermaid renderer inside Slack. It grew into a diagram workspace built around the place where architecture and product decisions already happen — the conversation itself.
The workflow
- Describe it — mention
@arialine, use a message shortcut, paste Mermaid, or attach a.mmdfile. - Render it — Arialine writes the Mermaid and posts both an interactive HTML artifact and a PNG fallback into Slack.
- Evolve it — reply in the same thread with changes such as “add a cache” or “show this as a Gantt chart.” Each edit creates a numbered version instead of overwriting history.
- Trace it — a decision ledger records what changed, why it changed, who requested it, and which Slack message caused it.
- Branch it — explore alternatives without touching the original board, then undo, rewind, compare, or adopt the result.
Slack-native features
- Plain-language creation and editing directly in channels, DMs, and threads
- Interactive Mermaid renders with PNG fallbacks for mobile and previews
- Additive version history with undo, rewind, and branching
- Review mode for proposed edits that require approval
- Markdown-to-Slack-Canvas rendering, including embedded Mermaid blocks
- A Model Context Protocol server that exposes diagram tools to Slack AI
- Explanations tied back to the exact decision and source message
Architecture
The production stack runs as a Docker Compose deployment behind Caddy. A Python 3.12 Starlette service handles Slack events, OAuth, signatures, routing, and AI tool calls; a separate Node renderer runs Mermaid through headless Chromium; PostgreSQL stores installations, boards, versions, and decisions. Arialine also exposes the same board operations through FastMCP so Slack's built-in assistant can create, edit, inspect, and branch diagrams.
Why it exists
Diagramming tools usually pull a team away from Slack precisely when the conversation becomes worth visualizing. Arialine keeps the artifact beside the discussion that created it, so the diagram, its history, and the reasoning behind every line stay together.
Built for the Slack Agent Builder Challenge.