json-canvas

json-canvas is a skill for Claude Code, Codex from jxoesneon/Ciel. It costs 44 tokens per session (1,079 once invoked), scanned A, original, Apache-2.0.

A file format and workflow for creating visual canvases, mind maps, flowcharts, and project boards in JSON Canvas files. It stores positioned nodes, connecting edges, and groups as structured JSON.

In plain words
What is it for?
Use it to create canvases, add and connect text, file, and link nodes, arrange groups, edit existing diagrams, and validate the resulting file.
Why use it?
It lets an agent create or edit visual diagrams in a format that can be checked and updated programmatically.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to create canvases, add and connect text, file, and link nodes, arrange groups, edit existing diagrams, and validate the resulting file.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/jxoesneon/ciel/json-canvas
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add jxoesneon/Ciel --skill json-canvas
Clone the repo
git clone --depth 1 https://github.com/jxoesneon/Ciel

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for json-canvas

README.md
[![agentmods](https://agentmods.dev/badge/skills/jxoesneon/ciel/json-canvas/github.svg)](https://agentmods.dev/skills/jxoesneon/ciel/json-canvas)
Your own site
<a href="https://agentmods.dev/skills/jxoesneon/ciel/json-canvas"><img src="https://agentmods.dev/badge/skills/jxoesneon/ciel/json-canvas/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for json-canvas

Your own site · 80×15
<a href="https://agentmods.dev/skills/jxoesneon/ciel/json-canvas"><img src="https://agentmods.dev/badge/skills/jxoesneon/ciel/json-canvas.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 44 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,079 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00044 $0.01079
Opus 5 $0.00022 $0.00540
Sonnet 5 $0.00009 $0.00216
Haiku 4.5 $0.00004 $0.00108

Measured 8d ago against content hash 33bca2095714, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

json-canvas scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/json-canvas/SKILL.md · 74 lines

How it starts

The opening of the file, as written. The whole thing — 74 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CIEL ADAPTATION: JSON Canvas

Create and edit JSON Canvas files (.canvas) following the JSON Canvas Spec 1.0. Build visual canvases, mind maps, flowcharts, and project boards with typed nodes, connecting edges, and grouping containers.

File Structure

  • Two top-level arrays: {"nodes": [], "edges": []} (both optional)
  • nodes — placed objects; array order = z-index (first = bottom, last = top)
  • edges — connections referencing node IDs

Workflows

  • Create canvas: Base structure → generate unique 16-char hex IDs → add nodes (required: id, type, x, y, width, height) → add edges → validate
  • Add node: Parse existing → generate non-colliding ID → position with 50-100px spacing → append → optionally add edges → validate
  • Connect nodes: Identify source/target IDs → unique edge ID → set fromNode/toNode → optional fromSide/toSide/label → append → validate
  • Edit: Parse JSON → locate by id → modify attributes → write back → re-validate

Node Types

  • text: required text (Markdown-supported plain text)
  • file: required file (vault path); optional subpath (heading/block, starts with #)
  • link: required url (external URL)
  • group: optional label, background, backgroundStyle (cover/ratio/repeat); visually contains child nodes positioned inside its bounds

Generic Node Attributes

  • Required: id (16-char hex), type, x, y, width, height
  • Optional: color — preset "1"-"6" (red/orange/yellow/green/cyan/purple) or hex ("#FF0000")

Edge Attributes

  • Required: id, fromNode, toNode
  • Optional: fromSide/toSide (top/right/bottom/left), fromEnd/toEnd (none/arrow; default toEnd=arrow), color, label

Layout & IDs

  • Coordinates can be negative; x increases right, y increases down; position is top-left corner
  • Space nodes 50-100px apart; 20-50px padding inside groups; align to grid (multiples of 10-20)
  • Suggested sizes: small text 200-300×80-150; medium 300-450×150-300; file/link preview 250-500×100-400
  • IDs: 16-char lowercase hex (64-bit random), unique across BOTH nodes and edges

Read the full file on GitHub · 74 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 8d ago First seen · 74 lines · 44 tokens per session scan A 33bca2095714

Subscribe to this mod's changes

json-canvas is a skill published in the GitHub repository jxoesneon/Ciel (1 stars, last pushed 4d ago), licensed Apache-2.0. It adds 44 tokens to every session and 1,079 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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