muriel

muriel is a Claude Code skill that produces visual artifacts across sixteen channels — fourteen output + two cross-channel references — enforcing an 8:1 contrast floor and brand-token discipline at render time. Design tokens import from design.md and export to W3C DTCG; a vision-model critique agent audits the output; the floor never bends.

A single skill file (SKILL.md) teaches the agent to generate every visual artifact a researcher-designer-engineer ships — from text source files that diff in git and regenerate from data. The constraint discipline (8:1 contrast, OLED palette, one font treatment, generated > drawn, reproducible > one-off) stays live at render time: brand tokens are parsed, contrast is audited, dimensions are enforced — not as lint after the fact, but as part of the act of making.

Heir projects — swap in your favorites

muriel is the grandmother to marginalia (editorial callouts and magazine layouts, cited throughout channels/web.md) and iblipper (kinetic typography and emotional-vocabulary animation, cited in vocabularies/kinetic-typography.md). Both grew from the same constraint discipline and ship as the defaults here because they're tuned to pass muriel's rules out of the box.

They're defaults, not requirements. The constraint discipline — 8:1 contrast, OLED palette, one font treatment, brand tokens live at render time — is the backbone. The specific libraries are preferences. Swap in your favorite editorial library, kinetic-typography engine, chart renderer, style-guide loader, imagegen provider, or rasterizer; muriel's opinions are about what constraints hold, not which library enforces them. Every channel doc names which library it assumes, and none of those assumptions are load-bearing against a sensible substitute.

Built on / integrates with

Python channels

Editorial

Interactive / graphics

Diagrams / video

Channels

Fourteen output channels, each with its own subfile under channels/:

• Raster (Pillow + typeset.py) — store assets, icons, banners, wordmarks, screenshot designs
• Vector / SVG (svgwrite, cairosvg, Mermaid, Excalidraw) — paper figures, data-driven diagrams, scalable icons, flowcharts
• Web (marginalia + Playwright + weasyprint) — blog posts, callouts, magazine layouts, DOM → PNG/PDF capture
• Interactive (WebGL / Canvas / D3 / PixiJS) — live demos with parameter sliders, sci-fi UI scaffolds
• Video (ffmpeg + desktop-control + hyperframes) — product demos, GIFs, HTML → MP4 compositions
• Terminal (Unicode charts via chart.py) — sparklines, bar charts, tables
• Density viz (typeset.render_heatmap()) — Tobii-style fixation heatmaps
• Gaze plots — scanpath, bubble scanpath, AOI timeline, saccade rose, approach-retreat
• Science (matplotlib + LaTeX + muriel.stats) — paper figures, notebook editorial, APA reporting
• Charts (Recharts / ECharts / Chart.js / Plotly / D3) — JS chart-library guidance with 22 numbered rules, anti-pattern detection, and muriel-strict 8:1 color tokens. matplotlib lives in Science. See channels/charts.md.
• Infographics (deterministic SVG) — single-image explainers, 10 types × layout patterns × colorblind-safe palettes
• Diagrams (deterministic SVG) — rhetorical primitives: 2×2 matrix, N-step cycle, Venn shipped, plus Mermaid → SVG/ASCII and TeX → SVG (MathJax) Node-bridges; comparison pair, funnel, stack, DAG, spectrum, pyramid, heat-grid queued. Each preset carries an epistemic precondition + anti-prescription
• Spatial (muriel.spatial + render_assets/) — depth scaffolding for layered typography + scalar-field topology. Static SVG perspective grids (1pt / 2pt / 3pt / iso) where grid() scaffolds space, plus ridgemap() — a sibling primitive that scaffolds scalar fields as stacked 1D slices (Joy Division / Harold Craft 1970 pulsar plot lineage). Three.js + CSS3DRenderer exemplars share one helper lib. Cooper VLW / Mackinlay-Robertson-Card / Dumais Data Mountain lineage. See channels/spatial.md.
• Polish (CSS / TSX / HTML micro-interaction discipline) — UI polish + visual-detail rules: concentric border radius (outer = inner + padding), optical alignment, shadows-over-borders, scale-on-press (0.96, never below 0.95), contextual icon animations (scale 0.25→1 + blur 4px→0 + bounce: 0), 40×40px hit area, no transition: all, tabular nums, text-wrap: balance / pretty, macOS font smoothing. 16 numbered rules, mined from thedavidmurray/claude-make-interfaces-feel-better (MIT, archived) with muriel's 8:1 contrast floor still binding. See channels/polish.md.

Plus two cross-channel references used by every channel:

• Dimensions (channels/dimensions.md) — social cards, device footprints, viewport tiers, paper sizes, video resolutions
• Style guides (channels/style-guides.md) — brand.toml schema, motion tokens, CSS / matplotlibrc derivation, ownership rules. Round-trips through Google Stitch design.md import (muriel import) and W3C Design Tokens (DTCG) export (muriel export-dtcg), so brand.toml plugs into style-dictionary, theo, Figma tokens-studio, token-css, and the iOS / Android / Tailwind pipelines downstream.

Philosophy — multi-constraint solving

muriel is a multi-constraint solver for visual production. The tooling is LLM-native (skill format, vision-model critique, brand tokens alive at render time, motion as a first-class schema field, engine adapters for Pillow / Flux / pretext / ffmpeg / Playwright). The principles are older: Cooper's Visible Language Workshop, Tufte's data-ink discipline, Bertin's retinal variable ranking, Gestalt grouping, CRAP layout, Reichle's E-Z Reader, scanpath patterns from vision science. The tools serve the principles.

Install

Where things live. The skill's canonical source is plugins/muriel/skills/compose/SKILL.md. The repo root's .claude-plugin/ holds only marketplace.json; the plugin's own manifest lives at plugins/muriel/.claude-plugin/plugin.json (a root-level manifest isn't needed when the marketplace source points to a subdirectory). The committed .agents/skills/muriel symlink is a deliberate cross-harness bridge (see Other AI harnesses below), not a stray copy.

As a Claude Code plugin (recommended)

From any Claude Code session:

/plugin marketplace add andyed/muriel
/plugin install muriel@andyed-muriel

That's it — no clone, no symlinks. /plugin uninstall reverses cleanly. Invoke with /muriel:compose (plugin skills are namespaced; the muriel: prefix prevents collisions with other plugins). The muriel-critique subagent loads alongside the skill.

As a Claude Code skill (developer install)

If you're working on the muriel repo itself, install from a checkout so edits show up live:

git clone https://github.com/andyed/muriel ~/Documents/dev/muriel
cd ~/Documents/dev/muriel && ./install.sh

The script symlinks plugins/muriel/skills/compose/ into ~/.claude/skills/muriel/ (so the bare /muriel invocation continues to work) and the critique agent into ~/.claude/agents/. It refuses if the plugin install is already present, to avoid double-loading.

As a Python package

pip install -e ~/Documents/dev/muriel   # source install (editable)
# pip install muriel                    # PyPI — not yet published; track via GitHub Releases
pip install https://github.com/andyed/muriel/releases/download/v0.11.0/muriel-0.11.0-py3-none-any.whl

Then, from any script or notebook:

from muriel import matplotlibrc_dark            # auto-applies an OLED matplotlibrc on import
from muriel.stats import format_comparison      # APA-style reporting helpers
from muriel.contrast import audit_svg           # WCAG 8:1 audit, module + CLI
from muriel.styleguide import load_styleguide   # brand.toml loader with aliases + motion
from muriel.dimensions import figsize_for, OG_CARD

As a CLI

After pip install, the muriel command dispatches to every subcommand:

muriel                              # list subcommands
muriel capture https://example.com  # responsive screenshot sweep
muriel contrast audit page.svg      # WCAG 8:1 audit
muriel dimensions                   # print the dimensions registry
muriel heroshot in.png out.png --tilt 12 --brand brand.toml --target og.card
muriel tilt-shift raw.png hero.png  # fake-lens depth-of-field blur
muriel venn spec.json out.png       # area-proportional Euler diagram
muriel styleguide brand.toml --css  # derive CSS :root custom properties

Each subcommand is also callable directly via python -m muriel.capture, python -m muriel.tools.heroshot, etc.

The critique agent

The muriel-critique subagent ships with the plugin and is loaded automatically by both install paths above (plugin install and install.sh). Dispatch it from any Claude Code session with the Agent tool, subagent_type: muriel-critique. See Critique agent below.

Other AI harnesses (Cursor, Codex, Gemini CLI, GitHub Copilot, Kiro, OpenCode, Pi, Qoder, Rovo Dev, Trae, …)

The canonical SKILL.md at plugins/muriel/skills/compose/SKILL.md uses the Agent Skills format that's portable across most agent harnesses. The repo ships a .agents/skills/muriel symlink to the canonical source — read natively by Codex CLI and as an alternate path by Cursor, Gemini CLI, GitHub Copilot, OpenCode, and Pi. Per-harness verification is unfinished; see HARNESSES.md for the rollout plan and the verification checklist. Kiro, Qoder, Rovo Dev, and Trae need per-harness manifest shims (P1, not yet landed).

Dependencies (by channel)

Channel	Required	Optional
Raster	Python 3, Pillow	muriel/typeset.py for templates
SVG	none (hand-rolled)	svgwrite, drawsvg, cairosvg, rsvg-convert, Mermaid CLI, mcp_excalidraw for live-canvas refinement
Web (editorial)	marginalia (CDN)	pandoc 3.x for markdown → HTML
Web (static capture)	Playwright or weasyprint	headless Chrome
Interactive	modern browser	D3, Three.js, p5.js, PixiJS v8 (CDN)
Video	ffmpeg (full build: brew tap homebrew-ffmpeg/ffmpeg)	hyperframes for HTML → MP4; desktop-control for automated capture
Terminal	Python 3	muriel/chart.py
Density viz / Gaze	Python 3, Pillow	muriel/typeset.py render_heatmap()
Science	Python 3	matplotlib, NumPy (for figures); muriel.stats / muriel.matplotlibrc_{dark,light} / muriel.dimensions ship stdlib-only
Infographics	Python 3	svgwrite, cairosvg for raster export
Dimensions	Python 3	— (stdlib-only reference module)
Style guides	Python 3	tomli on 3.10 (3.11+ has tomllib); optional matplotlib for rcparams derivation

Universal rules

Encoded in SKILL.md and enforced across every channel:

• 8:1 contrast minimum on all text (compute WCAG ratio)
• Decorative elements ≥55/255 on dark backgrounds
• Measure before drawing (bbox / viewBox / getBoundingClientRect)
• OLED palette: cream on near-black, not pure white
• Generated > drawn. If data can drive it, it should.
• Reproducible > one-off. Save the script alongside the output.

Critique agent

muriel ships a vision-model critique agent at plugins/muriel/agents/muriel-critique.md. It reads a rendered artifact and names — with evidence — every way the artifact fails muriel's rules, channel anti-patterns, and (optionally) a brand.toml's tokens. Read-only tools (Read / Glob / Grep), hardened against prompt-injection, badge-laundering, and contrast-claim spoofing embedded in the image itself.

Install: the subagent ships with the muriel plugin and is loaded automatically by both install paths in Install above (plugin install via /plugin install muriel@andyed-muriel and the developer install.sh route). No manual symlinks required.

Invoke from any Claude Code session:

"Run muriel-critique on path/to/artifact.png with channel raster and brand examples/muriel-brand.toml."

Output: a structured markdown critique with a verdict (PASS / NEEDS REVISION / FAIL), a numbered issue list (rule / evidence / fix, severity-tagged), and a rationale. CRITICAL severity → FAIL; any HIGH → NEEDS REVISION; otherwise PASS.

Regression fixtures: adversarial and baseline artifacts for the critique agent live at examples/critique-fixtures/ with their expected verdicts. Contribute new attacks there — any CVE for visual-critic systems can be a one-paragraph pull request.

Showcase

• muriel.mindbendingpixels.com — muriel's own landing page and gallery. Six "Featured work" exhibits spanning science, infographics, gaze plots, and dashboard registers; an interactive motion-tuner for the brand's duration + easing tokens; install + critique-agent docs in condensed form. Built with muriel, hosted on the mindbendingpixels subdomain. OLED palette throughout, clearing the 8:1 floor every channel doc enforces.
• Scrutinizer — Brand & Perceptual Tokens — Live page that uses muriel end-to-end: the scrutinizer-brand.toml StyleGuide, the foveal_overlay primitive (port of the in-app overlay), the engine_sectors_overlay primitive (Blauch et al. 2026 isotropic cortical sectors), the palettes module (Wong / IBM / Tol), and the contrast/dimension constants. The page also exposes Scrutinizer's perceptual decay constants (SIGMA_LM, SIGMA_BY, CMF_A, etc.) for designers building peripheral-aware UI. First public artifact of the muriel + Scrutinizer integration.

Related prior art

• anthropics/skills (Apache-2.0) — Anthropic's official skill monorepo. Seventeen skills covering the breadth of agent surfaces, of which seven sit in muriel's territory: brand-guidelines (Anthropic's seven brand colors + Poppins/Lora typography applied via python-pptx; the canonical example of single-palette + single-typography-pair brand application), theme-factory (ten named themes — Ocean Depths, Sunset Boulevard, Forest Canopy, Modern Minimalist, Golden Hour, Arctic Frost, Desert Rose, Tech Innovation, Botanical Garden, Midnight Galaxy — plus an "ask the user, vibe-generate a similar one" custom-theme path), canvas-design (PNG/PDF visual art with a custom canvas-fonts directory), frontend-design (UI/UX templates), web-artifacts-builder (HTML artifacts with React + Tailwind), algorithmic-art (p5.js generative with seeded randomness), slack-gif-creator (size-constrained animated GIFs). muriel positions on the same surface but with stricter constraints: 11 palettes vs 1, two-tier text-safe/decorative-only vs ungated, contrast-by-construction generation (muriel.palettes.generate_for_floor()) vs pick-from-menu, 8:1 floor vs no contrast guarantee, motion tokens in brand.toml vs no motion vocabulary, audit pipeline vs apply-and-ship. Anthropic ships breadth (17 skills across many domains); muriel ships depth on this one. Useful baseline to position any new muriel feature against.
• pbakaus/impeccable (Apache-2.0, Skill 3.1.1, May 2026) — Paul Bakaus' open-source design skill for AI coding harnesses, extended from Anthropic's original frontend-design skill. Now ships seven domain reference files (Typography, Color & Contrast, Spatial, Motion, Interaction, Responsive, UX Writing), twenty-three /impeccable:* commands (craft, critique, audit, polish, bolder, quieter, distill, harden, animate, colorize, typeset, layout, …), twenty-seven deterministic anti-pattern rules plus twelve LLM-critique rules, and a standalone npx impeccable detect CLI (regex + Puppeteer screenshot scan, no API key required) that emits JSON for twenty-four detectable issues. Packaged across eleven harnesses (Claude Code, Cursor, Codex CLI, Gemini CLI, GitHub Copilot, Kiro, OpenCode, Pi, Qoder, Rovo Dev, Trae). muriel's Absolute bans section in channels/web.md and the reflex-fonts anti-pattern are rephrased from impeccable. Where impeccable is single-surface + JS-side and ships its own detector, muriel is multi-channel + Python-native with a vision-model critique agent; they complement — chaining muriel capture → npx impeccable detect → muriel-critique is the strongest pipeline for "render → static-rule scan → vision-critic" on a web surface. muriel's cross-harness rollout in HARNESSES.md mirrors impeccable's packaging matrix.
• nexu-io/html-anything (Apache-2.0, 4.7k★) — agentic HTML editor with ~75 surface archetypes grouped into nine families (decks, frames / motion, social cards, web prototypes, articles, office / PM docs, dashboards, posters, specialized), each rendered as single-file HTML; one-click export to PNG / WeChat / X / Zhihu. The closest contemporary to a fully-fleshed surfaces catalog — muriel cites it rather than rebuilding the taxonomy. Surveyed in vocabularies/surfaces.md; patterns mined include the typed frontmatter shape (category / scenario / aspect_hint / featured / recommended / example_source_url), the "absolute rules per surface" enforcement pattern (deck-swiss-international's border-radius: 0 everywhere, 22 locked layouts S01–S22, locked 4-theme palette with no hex modification), CJK-first font stacks (Latin display + Noto Sans SC), and the "inspired by" lineage chain shipped as data not prose. Take/keep-ours mapping in the Sibling skills table. Full surface implementation queued.
• pixijs/pixijs-skills (MIT) — source of truth for the PixiJS vocabulary. Curated subset documented at vocabularies/pixijs.md; upstream is where the depth lives.
• caylent/tufte-data-viz (MIT) — Edward Tufte's data-viz principles as an agent skill: 22 numbered rules + per-library quick-reference for Recharts, ECharts, Chart.js, matplotlib, Plotly, D3/SVG. The structural model behind muriel's channels/charts.md — we ported the rule structure, per-library config tables, and anti-pattern PATTERN→FIX detection format, then overrode the color tokens because Tufte's published palette fails muriel's 8:1 floor (their #666 series and #e41a1c accent score 5.7 and 4.7). Specific divergences logged in the Sibling skills table.
• K-Dense-AI/scientific-agent-skills (MIT) — research-skill family covering matplotlib, statistical-analysis, scientific-critical-thinking, market-research, pptx, markitdown, literature-review, hypothesis-generation, scientific-schematics. Several modules overlap muriel's channels/science.md and queued channels (market-research, pptx). muriel borrows test-selection vocabulary, the generate→render→inspect PPTX inspection loop, and the GRADE/Cochrane bias taxonomy; we keep our standard-library-only muriel.stats (no scipy/pingouin) and 8:1 audit on every figure. Take/keep-ours mapping in the Sibling skills table.
• matplotlib-venn — area-proportional Euler renderer that backs muriel/tools/venn.py.
• geraldnguyen/social-media-posters (MIT) — Python + GitHub Actions CLI for posting to X / LinkedIn / Instagram / Threads / Bluesky / YouTube. Sits downstream of muriel: muriel produces the OG card at the right dimensions, audits contrast, applies brand tokens; social-media-posters sends it. The top-level muriel CLI's subcommand-dispatch pattern is borrowed from their social_cli/.
• yizhiyanhua-ai/fireworks-tech-graph (MIT) — Claude Code skill that renders SVG technical-architecture diagrams (14 UML types + AI/agent-system diagrams like RAG pipelines, multi-agent orchestration, tool-call flows) from natural-language descriptions. The closest living example of system-architecture diagram generation; useful reference as muriel's channels/diagrams.md catalog grows past the matrix + cycle MVP toward causal DAG and stack primitives.
• webadderall/Recordly (AGPL-3.0, desktop app — not vendored, integrated only) — macOS/Windows/Linux screen-recording app with auto-zoom cursor following, cursor polish, motion-blur regions, webcam overlay, and styled frames, built on PixiJS. Recommended upstream of muriel's channels/video.md tooltip-burn + ffmpeg recipes for product-demo / walkthrough videos. AGPL means muriel never embeds or imports Recordly; the integration is purely filesystem/MP4 hand-off.
• yctimlin/mcp_excalidraw (MIT) — MCP server + Claude Code skill that exposes 26 programmatic tools over Excalidraw (create/move/align/distribute/group shapes, export/import .excalidraw JSON, Mermaid convert, live canvas at localhost:3000). Complementary to muriel: muriel generates SVG/raster artifacts deterministically from specs; mcp_excalidraw lets a Claude Code agent manipulate diagrams in a live canvas with the draw-observe-adjust loop. Pairs cleanly with the planned muriel.authoring.excalidraw emitter — muriel writes the .excalidraw source file, mcp_excalidraw opens it for iterative refinement, muriel re-audits on re-export.
• thedavidmurray/claude-make-interfaces-feel-better (MIT, archived May 2026) — Design-engineering principles for UI polish: typography / surfaces / animations / performance split into four reference files plus a skill.md index. The structural model + 16 numbered rules behind muriel's channels/polish.md — we ported the whole rule set verbatim because the values are tuned (concentric outer = inner + padding, exact scale(0.96) press never below 0.95, exact scale 0.25→1 + bounce: 0 for contextual icon swaps, 40×40px hit area, ~100ms stagger between semantic chunks) and overrode by adding the 8:1 contrast floor as a binding gate on top of the polish layer. Sits in a different lane from impeccable — impeccable runs deterministic anti-pattern detection over a rendered page; this codifies the design-engineering recipes you reach for when authoring the page.
• wrsmith108/visual-prompt-coach (license unspecified) — Claude Code skill that converts unstructured visual requests for technical course materials into framework-informed prompts. Operationalises Dan Roam (6×6 / SQVID classification), Mayer's multimedia learning principles (coherence as removal rule, signaling as emphasis rule), C4 architecture-diagram leveling, cognitive load theory (element-count caps by audience prior knowledge), and Gestalt / CRAP for layout. Asks up to four intake questions (learning objective, what's shown, audience prior knowledge, constraints) before producing the prompt artifact — the exact shape muriel's queued constraint-elicitation rule landed on independently, which validates the cap. Lacks a critique / scoring layer downstream; muriel.critique provides the natural complement. Cognitive-science framing pairs with muriel's agents/muriel-critique.md and the queued 5-dimension critique scoring (where Mayer's coherence / signaling / contiguity could become evaluation axes).
• dot-Justin/teenage-engineering-ui-ux-skill (license unspecified) — Web-UI skill that generates interfaces in Teenage Engineering's visual register through procedural rules (proportional viewport layout, thin lowercase type, en-dashed product codes, true-black + warm-white surfaces) rather than asset replication. Frames the curator stance explicitly as "inspired-by, not cloned" — extracts transferable design DNA (layout logic, typographic hierarchy, color relationships) while excluding proprietary assets (logos, product drawings, brand copy). Format adopts Google Labs DESIGN.md. Validates the same stance muriel takes on nexu-io/open-design and the curator workflow in SKILL.md — useful external precedent when explaining muriel's mining ethos to a new contributor.
• Skill-discovery indices — Three community-curated registries useful when scoping muriel's territory or evaluating whether a domain is already covered before adding a channel: VoltAgent/awesome-agent-skills (1000+ skills, multi-harness, the highest-signal index), sickn33/antigravity-awesome-skills (1,400+ skills with an installer CLI), travisvn/awesome-claude-skills (community-curated, Claude-focused). Most entries are pure-development or productivity skills — muriel-overlapping skills are a small minority. Use these to discover candidates for the SKILL.md Sibling-skills table; don't treat the indices themselves as authoritative.

License

MIT. See LICENSE.