json-canvas

Q: How do I install json-canvas?

Run npx skills add https://github.com/guanyang/open-agent-hub --skill json-canvas in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/json-canvas/ (personal) or .claude/skills/json-canvas/ (project).

by guanyangProductivity & Automation

Create and edit JSON Canvas files (.canvas) with nodes, edges, groups, and connections. Use when working with .canvas files, creating visual canvases, mind maps, flowcharts, or when the user mentions Canvas files in Obsidian.

Installs: 294
Last 24h: —
Trending rank: —
Security: Not audited

Install

Works with every agent the skills CLI supports.

npx skills add https://github.com/guanyang/open-agent-hub --skill json-canvas

01
Install
Run the command in your project. The CLI asks which agents to install for.
02
Describe the task
Ask your agent for something this skill covers. It loads json-canvas automatically when relevant.
03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.

SKILL.md

The instructions your agent reads when the skill is triggered.

JSON Canvas Skill

File Structure

A canvas file (.canvas) contains two top-level arrays following the JSON Canvas Spec 1.0:

{
  "nodes": [],
  "edges": []
}

nodes (optional): Array of node objects
edges (optional): Array of edge objects connecting nodes

Common Workflows

1. Create a New Canvas

Create a .canvas file with the base structure {"nodes": [], "edges": []}
Generate unique 16-character hex IDs for each node (e.g., "6f0ad84f44ce9c17")
Add nodes with required fields: id, type, x, y, width, height
Add edges referencing valid node IDs via fromNode and toNode
Validate: Parse the JSON to confirm it is valid. Verify all fromNode/toNode values exist in the nodes array

2. Add a Node to an Existing Canvas

Read and parse the existing .canvas file
Generate a unique ID that does not collide with existing node or edge IDs
Choose position (x, y) that avoids overlapping existing nodes (leave 50-100px spacing)
Append the new node object to the nodes array
Optionally add edges connecting the new node to existing nodes
Validate: Confirm all IDs are unique and all edge references resolve to existing nodes

3. Connect Two Nodes

Identify the source and target node IDs
Generate a unique edge ID
Set fromNode and toNode to the source and target IDs
Optionally set fromSide/toSide (top, right, bottom, left) for anchor points
Optionally set label for descriptive text on the edge
Append the edge to the edges array
Validate: Confirm both fromNode and toNode reference existing node IDs

4. Edit an Existing Canvas

Read and parse the .canvas file as JSON
Locate the target node or edge by id
Modify the desired attributes (text, position, color, etc.)
Write the updated JSON back to the file
Validate: Re-check all ID uniqueness and edge reference integrity after editing

Nodes

Nodes are objects placed on the canvas. Array order determines z-index: first node = bottom layer, last node = top layer.

Generic Node Attributes

Attribute	Required	Type	Description
`id`	Yes	string	Unique 16-char hex identifier
`type`	Yes	string	`text`, `file`, `link`, or `group`
`x`	Yes	integer	X position in pixels
`y`	Yes	integer	Y position in pixels
`width`	Yes	integer	Width in pixels
`height`	Yes	integer	Height in pixels
`color`	No	canvasColor	Preset `"1"`-`"6"` or hex (e.g., `"#FF0000"`)

Text Nodes

Attribute	Required	Type	Description
`text`	Yes	string	Plain text with Markdown syntax

{
  "id": "6f0ad84f44ce9c17",
  "type": "text",
  "x": 0,
  "y": 0,
  "width": 400,
  "height": 200,
  "text": "# Hello World\n\nThis is **Markdown** content."
}

Newline pitfall: Use \n for line breaks in JSON strings. Do not use the literal \\n -- Obsidian renders that as the characters \ and n.

File Nodes

Attribute	Required	Type	Description
`file`	Yes	string	Path to file within the system
`subpath`	No	string	Link to heading or block (starts with `#`)

{
  "id": "a1b2c3d4e5f67890",
  "type": "file",
  "x": 500,
  "y": 0,
  "width": 400,
  "height": 300,
  "file": "Attachments/diagram.png"
}

Link Nodes

Attribute	Required	Type	Description
`url`	Yes	string	External URL

{
  "id": "c3d4e5f678901234",
  "type": "link",
  "x": 1000,
  "y": 0,
  "width": 400,
  "height": 200,
  "url": "https://obsidian.md"
}

Group Nodes

Groups are visual containers for organizing other nodes. Position child nodes inside the group's bounds.

Attribute	Required	Type	Description
`label`	No	string	Text label for the group
`background`	No	string	Path to background image
`backgroundStyle`	No	string	`cover`, `ratio`, or `repeat`

{
  "id": "d4e5f6789012345a",
  "type": "group",
  "x": -50,
  "y": -50,
  "width": 1000,
  "height": 600,
  "label": "Project Overview",
  "color": "4"
}

Edges

Edges connect nodes via fromNode and toNode IDs.

Attribute	Required	Type	Default	Description
`id`	Yes	string	-	Unique identifier
`fromNode`	Yes	string	-	Source node ID
`fromSide`	No	string	-	`top`, `right`, `bottom`, or `left`
`fromEnd`	No	string	`none`	`none` or `arrow`
`toNode`	Yes	string	-	Target node ID
`toSide`	No	string	-	`top`, `right`, `bottom`, or `left`
`toEnd`	No	string	`arrow`	`none` or `arrow`
`color`	No	canvasColor	-	Line color
`label`	No	string	-	Text label

{
  "id": "0123456789abcdef",
  "fromNode": "6f0ad84f44ce9c17",
  "fromSide": "right",
  "toNode": "a1b2c3d4e5f67890",
  "toSide": "left",
  "toEnd": "arrow",
  "label": "leads to"
}

Colors

The canvasColor type accepts either a hex string or a preset number:

Preset	Color
`"1"`	Red
`"2"`	Orange
`"3"`	Yellow
`"4"`	Green
`"5"`	Cyan
`"6"`	Purple

Preset color values are intentionally undefined -- applications use their own brand colors.

ID Generation

Generate 16-character lowercase hexadecimal strings (64-bit random value):

"6f0ad84f44ce9c17"
"a3b2c1d0e9f8a7b6"

Layout Guidelines

Coordinates can be negative (canvas extends infinitely)
x increases right, y increases down; position is the top-left corner
Space nodes 50-100px apart; leave 20-50px padding inside groups
Align to grid (multiples of 10 or 20) for cleaner layouts

Node Type	Suggested Width	Suggested Height
Small text	200-300	80-150
Medium text	300-450	150-300
Large text	400-600	300-500
File preview	300-500	200-400
Link preview	250-400	100-200

Validation Checklist

After creating or editing a canvas file, verify:

All id values are unique across both nodes and edges
Every fromNode and toNode references an existing node ID
Required fields are present for each node type (text for text nodes, file for file nodes, url for link nodes)
type is one of: text, file, link, group
fromSide/toSide values are one of: top, right, bottom, left
fromEnd/toEnd values are one of: none, arrow
Color presets are "1" through "6" or valid hex (e.g., "#FF0000")
JSON is valid and parseable

If validation fails, check for duplicate IDs, dangling edge references, or malformed JSON strings (especially unescaped newlines in text content).

Complete Examples

See references/EXAMPLES.md for full canvas examples including mind maps, project boards, research canvases, and flowcharts.

References

FAQ

What does the json-canvas skill do?

How do I install json-canvas?

Run npx skills add https://github.com/guanyang/open-agent-hub --skill json-canvas in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/json-canvas/ (personal) or .claude/skills/json-canvas/ (project).

Which AI agents can use json-canvas?

Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.

Is json-canvas safe to install?

No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.

Who maintains json-canvas?

It is published by guanyang in guanyang/open-agent-hub. It has 294 recorded installs.

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json-canvas

Install

Install

Describe the task

Review the result

SKILL.md

JSON Canvas Skill

File Structure

Common Workflows

1. Create a New Canvas

2. Add a Node to an Existing Canvas

3. Connect Two Nodes

4. Edit an Existing Canvas

Nodes

Generic Node Attributes

Text Nodes

File Nodes

Link Nodes

Group Nodes

Edges

Colors

ID Generation

Layout Guidelines

Validation Checklist

Complete Examples

References

FAQ

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