canvas

Canvas

Treat a canvas as a vault-scoped JSON Canvas document. Keep reads read-only and

route every requested mutation through one recoverable transaction.

Resolve the installed product root from this skill's own location, not from the

vault or current working directory:

PRODUCT_ROOT=/absolute/path/to/installed/claude-obsidian
CORE="$PRODUCT_ROOT/scripts/claude-obsidian.py"
test -f "$CORE"

Every ../wiki/references/ link in this file resolves the same way, relative

to this skill's own directory under $PRODUCT_ROOT, never relative to the

selected vault's wiki/ directory.

Choose the syntax source

Prefer a separately installed kepano/obsidian-skills json-canvas skill for

format details. Otherwise read [references/canvas-spec.md](references/canvas-spec.md).

The open standard is JSON Canvas 1.0.

Use this skill for vault workflow and transaction safety even when an upstream

syntax skill is available.

Scope

• Resolve the user vault before reading. Never derive it from plugin files.
• Store boards under wiki/canvases/; use wiki/canvases/main.canvas only as

the default when the user did not name a board.

• Treat wiki/canvases/index.md as an optional catalog. Update it only when a

canvas is created, renamed, or removed.

• Use vault-relative paths in file and background; reject absolute paths,

.. traversal, home shortcuts, and paths that escape through symlinks.

• Reference only files already inside the vault. If an optional capture or

media capability is detected, compose with it and consume its returned

vault-relative path. Do not assume a particular plugin, command, or session

log, and do not download or copy assets in this skill.

• Use link nodes for URLs. Accept HTTPS URLs only; a link node does not grant

permission to fetch the page. Creating its JSON makes no request, but opening

it in Obsidian may fetch Open Graph metadata from that URL's host. Disclose

that render-time egress and confirm it is acceptable; otherwise use a text

node containing the URL.

Read-only operations

For status or list requests, parse the selected .canvas files and report node

counts, group labels, broken edge endpoints, and missing vault-relative file

targets. If the default canvas is absent, report that fact and offer a creation

preview; do not create it during a status request.

Draft a mutation

1. Read the entire canvas and any catalog target. Record each expected SHA-256,

or null for a file that must be absent.

1. Preserve unknown JSON fields and existing array order. The node array is

bottom-to-top z-order.

1. Draft the requested nodes or edges:

• Give every node and edge a unique ID. Prefer a random 16-character

lowercase hexadecimal ID and verify it is unused.

• Require integer x, y, width, and height values for every node.
• Use text, file, link, or group exactly as defined by JSON Canvas.
• Require every fromNode and toNode to reference an existing or newly

drafted node.

1. Position new content deliberately. A group is a visual container, not a

parent. Use 20 px inner padding and 40 px gaps, wrap to a new row when

needed, and preview any group expansion.

1. Serialize valid UTF-8 JSON with top-level nodes and edges arrays.

Minimal node examples:

{
  "nodes": [
    {
      "id": "6f0ad84f44ce9c17",
      "type": "text",
      "text": "# Research map\n\nA concise orientation card.",
      "x": 0,
      "y": 0,
      "width": 400,
      "height": 180
    },
    {
      "id": "a1b2c3d4e5f67890",
      "type": "file",
      "file": "wiki/concepts/Contextual Retrieval.md",
      "x": 460,
      "y": 0,
      "width": 400,
      "height": 240
    }
  ],
  "edges": []
}

Use file plus optional subpath: "#Heading" for notes, images, PDFs, and

other vault files. Use url only on a link node. Escape line breaks in JSON

strings as \n, not as literal backslash-plus-n text.

Preview and apply

Validate before showing the preview:

• JSON parses and uses supported node types.
• IDs are unique and edge endpoints exist.
• dimensions are positive integers;
• file and background paths are safe, vault-relative, and present;
• new nodes do not unintentionally overlap or overflow their requested group.

Build one claude-obsidian.transaction.v1 bundle with operation type canvas.

Include the canvas and the catalog in that same bundle when the catalog changes.

Read [operation-transactions.md](../wiki/references/operation-transactions.md),

then inspect the bundle before applying it:

python3 "$CORE" transaction inspect BUNDLE --vault VAULT
# Set APPROVAL_SHA256 to the inspect result's approval_sha256 after review.
python3 "$CORE" transaction apply BUNDLE --vault VAULT \
  --approved-plan-sha256 "$APPROVAL_SHA256"

For removals, replacements, renames, or other destructive changes, obtain

explicit consent after presenting the preview. Report the operation ID, exact

changed paths, board name, node IDs, and final positions. Do not commit Git.