# Agentic Mermaid
**Beautiful diagrams, made with your agent.**
Agentic Mermaid is an open-source Mermaid toolkit for people who want AI agents to create diagrams that look finished: SVG and PNG renders, ASCII and Unicode for review, deterministic layout, and Style + Palette controls for brand colors, typography, strokes, fills, and backdrops.
It is forked from [`lukilabs/beautiful-mermaid`](https://github.com/lukilabs/beautiful-mermaid). Published on npm as `agentic-mermaid`; the GitHub repository is `adewale/agentic-mermaid`; the canonical live site is [`agentic-mermaid.dev`](https://agentic-mermaid.dev/), a Cloudflare Workers deployment.
[Live Demo & Samples](https://agentic-mermaid.dev/) · [Live Editor](https://agentic-mermaid.dev/editor)
Docs: [docs index](./docs/) · [getting started](./docs/getting-started.md) · [agent guide](./Instructions_for_agents.md) · [agent API cookbook](./docs/agent-api-cookbook.md) · [design system](https://github.com/adewale/agentic-mermaid/blob/main/DESIGN.md) · [skills](./skills/) · [fork differences](./docs/fork-differences.md) · [vs Mermaid & Beautiful Mermaid](./docs/comparison.md) · [changelog](./CHANGELOG.md)
## Why Agentic Mermaid
Use it when you want to describe a diagram in plain language and get back something you can publish without a design cleanup pass.
| You want | Agentic Mermaid gives you |
|---|---|
| An agent to draft the diagram | Mermaid source plus a verified render path |
| Beautiful defaults | Built-in looks such as `watercolor`, `blueprint`, `hand-drawn`, and `publication-figure` |
| Brand fit | Style + Palette stacks and custom JSON palettes you can keep in your repo |
| Safe edits later | `parseRegisteredMermaid` → family narrower → `mutate` → `verifyMermaid` → `serializeMermaid` |
| Reviewable artifacts | SVG, PNG, ASCII, Unicode, and JSON layout from the same source |
The agent workflow is the guardrail behind the polish: agents should not guess from pixels, concatenate strings, or regenerate whole diagrams when a structured edit is available.
## Highlights
- **Descriptor-registered diagram families** — built-ins and namespaced extensions share one discovery and capability contract.
- **SVG, PNG, ASCII, Unicode, JSON** — one resolved request with explicit graphical, terminal, and positioned-layout projections.
- **Synchronous, zero-DOM SVG renderer** — no Puppeteer, no browser flash.
- **Composable styles** — `{ style: ['hand-drawn', 'dracula'] }` stacks a look over a palette; discoverable full looks cover sketch, watercolor, blueprint, accessibility, print, operational, physical-media, architecture, and editorial/report use cases. Custom styles are plain JSON records any agent can author (`docs/style-authoring.md`). `seed` re-rolls the ink, never the layout.
- **Discoverable palettes + Shiki compatibility** — a theme is a palette-only style: discover the canonical catalog at runtime, theme from two colors, or adapt a VS Code theme.
- **Agent-native editing** — typed mutation for every registered renderable family; source-level round-trip only for opaque fallbacks containing unmodeled syntax.
- **CLI + MCP + library** — `am`, `agentic-mermaid-mcp`, `agentic-mermaid`, `agentic-mermaid/agent`, and the browser/workerd-safe `agentic-mermaid/agent/core`. Audit reports and trusted host-resource helpers remain repository tooling instead of published runtime entry points.
## Installation
```bash
npm install agentic-mermaid # or: bun add agentic-mermaid / pnpm add agentic-mermaid
npx --no-install agentic-mermaid --help
npx --no-install agentic-mermaid mcp
```
For repository development, install from source and run the Bun entrypoints
(Bun 1.4.0 or later; `bun upgrade` if `bun --version` is older):
```bash
git clone https://github.com/adewale/agentic-mermaid
cd agentic-mermaid
bun install
bun run build
bun run bin/am.ts --help
bun run bin/agentic-mermaid-mcp.ts # MCP stdio server
```
> **ESM-only.** `agentic-mermaid` ships ES modules (there is no CommonJS build);
> `require()` consumers should use dynamic `import()` instead. Requires Node ≥ 22.
>
> The `am …` examples below name the published bin. After a project-local npm
> install, invoke it from a shell as `npx --no-install agentic-mermaid …` (or
> from an npm script as `am …`). From a source checkout, use
> `bun run bin/am.ts …` instead.
## Output quick starts
Use `agentic-mermaid/agent` when you want one import path for styled renders, output formats, and the structured edit API.
### SVG
```ts
import { renderMermaidSVG } from 'agentic-mermaid/agent'
const svg = renderMermaidSVG(`flowchart TD
Start --> Done`, { security: 'strict' })
```
### PNG
```ts
import { writeFileSync } from 'node:fs'
import { renderMermaidPNG } from 'agentic-mermaid/agent'
const png = renderMermaidPNG(`flowchart TD
Start --> Done`, {
fitTo: { width: 1200 },
background: '#fff',
})
writeFileSync('diagram.png', png)
```
CLI equivalent:
```bash
am render diagram.mmd --format png --output diagram.png
```
### ASCII / Unicode
```ts
import { renderMermaidASCII } from 'agentic-mermaid/agent'
const unicode = renderMermaidASCII(`flowchart LR
A --> B`)
const ascii = renderMermaidASCII(`flowchart LR
A --> B`, { useAscii: true })
```
## Agent quick start
If your coding agent can read repo files, point it at:
- [`skills/agentic-mermaid-diagram-workflow/SKILL.md`](./skills/agentic-mermaid-diagram-workflow/SKILL.md) for diagram authoring/editing.
- [`skills/agentic-mermaid-live-editor/SKILL.md`](./skills/agentic-mermaid-live-editor/SKILL.md) for editor changes.
If it only has shell access:
```bash
am --agent-instructions
am capabilities --json
am preview diagram.mmd --security strict --open
am mutate diagram.mmd --op '{"kind":"add_node","id":"Cache","label":"Cache"}' --json
```
Zero-install prompt for a coding agent: read `https://agentic-mermaid.dev/llms.txt` and follow the parse → narrow → mutate → verify → serialize workflow. To wire Agentic Mermaid into another repo, run `npx agentic-mermaid init-agent` (or `bun run bin/am.ts init-agent` from a source checkout); it writes a non-clobbering `AGENTS.md` section, root `skills/` bundle, and `.mcp.json` sample.
Use strict `preview` for human inspection and `mutate --op/--ops` for verified one-shot or batched edits.
For multi-step MCP edits, connect `agentic-mermaid-mcp` and use Code Mode `execute(code)` with the same `mermaid.*` SDK names. Stdio is the default transport; `agentic-mermaid-mcp --transport http` starts HTTP/SSE and managed PNG file/URL artifacts. See the [agent API cookbook](./docs/agent-api-cookbook.md) for copy-pasteable library, CLI, and MCP recipes.
## MCP server
Agentic Mermaid ships a Model Context Protocol server so MCP-capable agents can render and safely edit diagrams without shelling out.
- **Self-hosted (default).** `agentic-mermaid-mcp` runs a stdio server exposing `execute` (Code Mode sandbox), `describe_sdk` (one family's mutation schema on demand), `render_png`, `describe`, `mutate`, and `build`. Prefer declarative edits; use `execute` for custom logic. Package runners can use `npx -y agentic-mermaid mcp`; the `mcp` argument routes the package-name binary to the same stdio server. Add `--transport http` for HTTP/SSE with managed PNG file/URL artifacts. See [`docs/mcp-http-transport.md`](./docs/mcp-http-transport.md) and [`docs/mcp-code-mode-rationale.md`](./docs/mcp-code-mode-rationale.md).
- **Hosted.** A stateless Streamable HTTP endpoint is available at `https://agentic-mermaid.dev/mcp` (tools: `execute`, `describe_sdk`, `render_svg`, `render_ascii`, `render_png`, `verify`, `describe`, `mutate`, and `build`; 64 KB input caps). Call `describe_sdk` for compact signatures or exact fields before authoring unfamiliar ops. It is MCP JSON-RPC only, not a REST render API. Hosted `execute` runs the same `mermaid.*` facade in a Cloudflare Dynamic Worker isolate with no network; hosted PNG returns base64 only.
Local-first is the default posture: prefer the library, CLI, or a self-hosted MCP for anything sensitive, offline, larger than the hosted caps, or needing local PNG file/URL artifacts. The hosted endpoint is a public, unauthenticated convenience for zero-install render/verify/describe and bounded structured edits.
Directory maintainers can use the canonical [MCP listing record](./docs/MCP-DIRECTORY-LISTINGS.md). Hosted data handling is described in the [MCP privacy notice](./docs/MCP-PRIVACY.md).
## Structured edit example
```ts
import { parseRegisteredMermaid, asFlowchart, mutate, verifyMermaid, serializeMermaid } from 'agentic-mermaid/agent'
const parsed = parseRegisteredMermaid('flowchart TD\n API --> DB')
if (!parsed.ok) throw new Error('parse failed')
const flow = asFlowchart(parsed.value)
if (!flow) throw new Error(`not a structured flowchart: ${parsed.value.kind}`)
const next = mutate(flow, { kind: 'add_node', id: 'Cache', label: 'Cache' })
if (!next.ok) throw new Error(next.error.message)
const verify = verifyMermaid(next.value)
if (!verify.ok) throw new Error(JSON.stringify(verify.warnings, null, 2))
const source = serializeMermaid(next.value)
```
Rules:
- Use the matching exported `as` narrower before mutating an existing structured diagram.
- Mutation ops use `kind`, not `type`.
- Run `verifyMermaid` before every commit point.
- Do not call `mutate` on opaque fallback bodies; the narrower returns `null` for unmodeled syntax.
## Supported diagram families
Family support is projected from the `FamilyDescriptor` registry; run
`am capabilities --json` for the live roster. (The Section A capability report
is no longer published.) See [diagram families](./docs/diagram-families.md) for syntax examples and
compatibility notes.
## More documentation
- [System architecture](https://github.com/adewale/agentic-mermaid/blob/main/docs/design/system/README.md) — **start here** for the rendered resolved-request, family-descriptor, positioned-artifact, and output-security overview (dogfooded, drift-proof).
- [API reference](./docs/api.md) — renderers, agent API, options, CLI/MCP pointers.
- [Agent API cookbook](./docs/agent-api-cookbook.md) — practical recipes for agents.
- [Theming](./docs/theming.md) — two-color themes, built-ins, Shiki compatibility.
- [Custom style cookbook](./docs/custom-style-cookbook.md) — JSON style files, screenshots, schema usage, and CLI commands.
- [Fonts in custom styles](./docs/custom-fonts.md) — font selection, SVG declarations, PNG directories, fallbacks, and browser usage.
- [React integration](./docs/react.md) — browser-safe, family-loaded rendering.
- [ASCII output](./docs/ascii.md) — terminal output, color modes, XY charts.
- [Mermaid config](./docs/config.md) — frontmatter, init directives, runtime config.
- [Features](./docs/features.md), [quality](./docs/quality.md), [security](./SECURITY.md), [fork differences](./docs/fork-differences.md).
- [Adding diagram types](https://github.com/adewale/agentic-mermaid/blob/main/docs/contributing/adding-diagram-types.md) for contributors.
## Live editor and examples
- [Examples](https://agentic-mermaid.dev/examples/) — supported families, Style + Palette combinations, and the rich shared examples corpus.
- [Live editor](https://agentic-mermaid.dev/editor) — SVG/PNG exports and URL sharing.
- [`examples/agent-loop.ts`](https://github.com/adewale/agentic-mermaid/blob/main/examples/agent-loop.ts)
- [`examples/mcp-vs-cli-complex-diagrams.ts`](https://github.com/adewale/agentic-mermaid/blob/main/examples/mcp-vs-cli-complex-diagrams.ts)
- [`examples/agent-improve-auth-flow.ts`](https://github.com/adewale/agentic-mermaid/blob/main/examples/agent-improve-auth-flow.ts)
## Attribution
Agentic Mermaid is a fork of Beautiful Mermaid by [Luki Labs](https://github.com/lukilabs/beautiful-mermaid). The ASCII rendering engine is based on [`mermaid-ascii`](https://github.com/AlexanderGrooff/mermaid-ascii) by Alexander Grooff and extended for Agentic Mermaid.
## License
MIT