canvas: Visual Reference Layer

The three knowledge capture layers:

• /save → text synthesis (wiki/questions/, wiki/concepts/)
• /autoresearch → structured knowledge (wiki/sources/, wiki/concepts/)
• /canvas → visual references (wiki/canvases/)

A canvas is a JSON file Obsidian renders as an infinite visual board. This skill reads and writes canvas JSON directly. Read references/canvas-spec.md for the full format reference before making any edits. This spec aligns with the JSON Canvas open standard.

Substrate preference (v1.7+): This skill is a self-contained fallback. Prefer `kepano/obsidian-skills` as the authoritative substrate — its json-canvas skill is the canonical spec reference. If you see a json-canvas skill available without the claude-obsidian: namespace, that is kepano's version: use it for spec questions. Continue to use this canvas skill for the wiki-scoped workflows (positioning into wiki/canvases/, /banana integration, zone layout) — those are unique to claude-obsidian and live above kepano's primitive. Install kepano: claude plugin marketplace add kepano/obsidian-skills.

Default Canvas

wiki/canvases/main.canvas

If it does not exist, create it:

{
  "nodes": [
    {
      "id": "title",
      "type": "text",
      "text": "# Visual Reference\n\nDrop images, PDFs, and notes here.",
      "x": -400, "y": -300, "width": 400, "height": 120, "color": "6"
    },
    {
      "id": "zone-default",
      "type": "group",
      "label": "General",
      "x": -400, "y": -140, "width": 800, "height": 400, "color": "4"
    }
  ],
  "edges": []
}

Operations

open / status (/canvas with no args)

1. Check if wiki/canvases/main.canvas exists.
2. If yes: read it, count nodes by type, list all group node labels (zone names).

Report: "Canvas has N nodes: X images, Y text cards, Z wiki pages. Zones: [list]"

1. If no: create it with the starter structure above.

Report: "Created main.canvas with a General zone."

1. Tell user: "Open wiki/canvases/main.canvas in Obsidian to view."

new (/canvas new [name])

1. Slugify the name: lowercase, spaces → hyphens, strip special chars.
2. Create wiki/canvases/[slug].canvas with the starter structure, title updated to # [Name].
3. Add entry to wiki/overview.md under a "## Canvases" subsection (append after the Current State section). Do not modify wiki/index.md. It uses a fixed section schema (Domains, Entities, Concepts, Sources, Questions, Comparisons).
4. Report: "Created wiki/canvases/[slug].canvas"

add image (/canvas add image [path or url])

Resolve the image:

• If URL (starts with http): download with curl -sL [url] -o _attachments/images/canvas/[filename]

Derive filename from URL path, or use img-[timestamp].jpg if unclear.

• If local path outside vault: cp [path] _attachments/images/canvas/
• If already vault-relative: use as-is.

Create _attachments/images/canvas/ if it doesn't exist.

Detect aspect ratio: Use python3 -c "from PIL import Image; img=Image.open('[path]'); print(img.width, img.height)" or identify -format '%w %h' [path]. See references/canvas-spec.md for the full aspect ratio → canvas size table (7 ratios including 4:3, 3:4, ultra-wide). Do not use an inline table here. The spec is the single source of truth for sizing.

Position using auto-layout (see Auto-Positioning section below).

Append node to canvas JSON and write.

Report: "Added [filename] to [zone] zone at position ([x], [y])."

add text (/canvas add text [content])

Create a text node:

{
  "id": "text-[timestamp]",
  "type": "text",
  "text": "[content]",
  "x": [auto], "y": [auto],
  "width": 300, "height": 120,
  "color": "4"
}

Position using auto-layout. Write and report.

add pdf (/canvas add pdf [path])

Same as add image. Obsidian renders PDFs natively as file nodes.

• Copy to _attachments/pdfs/canvas/ if outside vault.
• Fixed size: width=400, height=520.
• Report page count if you can determine it.

add note (/canvas add note [wiki-page])

1. Search wiki/ for a file matching the page name (case-insensitive, partial match ok).
2. Use the vault-relative path as the file field.

• Use "type": "file" (not "type": "link"): .md files use file nodes, not link nodes.
• "type": "link" takes a url: "https://...": it is for web URLs only.

1. Create a file node: width=300, height=100.
2. Position using auto-layout.

{
  "id": "note-[timestamp]",
  "type": "file",
  "file": "wiki/concepts/LLM Wiki Pattern.md",
  "x": [auto], "y": [auto],
  "width": 300, "height": 100
}

zone (/canvas zone [name] [color])

1. Read canvas JSON.
2. Find max_y: max(node.y + node.height for all nodes) + 60. Use 280 if no nodes (leaves room above the starter title node).
3. Create a group node:

{
  "id": "zone-[slug]",
  "type": "group",
  "label": "[name]",
  "x": -400,
  "y": [max_y],
  "width": 1000,
  "height": 400,
  "color": "[color or '3']"
}

Valid colors: "1"=red "2"=orange "3"=yellow "4"=green "5"=cyan "6"=purple

Write and report.

list (/canvas list)

1. glob wiki/canvases/*.canvas
2. For each canvas: read JSON, count nodes by type.
3. Report:

wiki/canvases/main.canvas      . 14 nodes (8 images, 3 text, 2 file, 1 group)
wiki/canvases/design-ideas.canvas. 42 nodes (30 images, 4 text, 8 groups)

from banana (/canvas from banana) (if the banana-claude plugin is installed)

1. Check wiki/canvases/.recent-images.txt first (session log of newly written images).
2. If not found or empty: use find with correct precedence (parentheses required. Without them -newer only binds to the last -name clause):

   python3 -c "import time,os; open('/tmp/ten-min-ago','w').close(); os.utime('/tmp/ten-min-ago',(time.time()-600,time.time()-600))"
   find _attachments/images -newer /tmp/ten-min-ago \( -name "*.png" -o -name "*.jpg" \)

Note: /banana is an optional external skill not shipped in this plugin. If the user has it installed, the .recent-images.txt log will be populated. If not, the find command above is the fallback.

1. If still none: show the 5 most recently modified images.
2. Present list: "Found N recent images: [list]. Add to canvas? Which zone? (zone name / 'new [name]' / 'skip')"
3. On confirmation: add each using the add image logic.

Auto-Positioning Algorithm

Read references/canvas-spec.md for the full coordinate system.

def next_position(canvas_nodes, target_zone_label, new_w, new_h):
    # Find zone group node
    zone = next((n for n in canvas_nodes
                 if n.get('type') == 'group'
                 and n.get('label') == target_zone_label), None)

    if zone is None:
        # No zone: place below all content
        max_y = max((n['y'] + n.get('height', 0) for n in canvas_nodes), default=-140)
        return -400, max_y + 60

    zx, zy = zone['x'], zone['y']
    zw, zh = zone['width'], zone['height']

    # Nodes inside this zone
    inside = [n for n in canvas_nodes
              if n.get('type') != 'group'
              and zx <= n['x'] < zx + zw
              and zy <= n['y'] < zy + zh]

    if not inside:
        return zx + 20, zy + 20

    rightmost_x = max(n['x'] + n.get('width', 0) for n in inside)
    next_x = rightmost_x + 40

    if next_x + new_w > zx + zw:
        # New row
        max_row_y = max(n['y'] + n.get('height', 0) for n in inside)
        return zx + 20, max_row_y + 20

    # Same row: align to the top of all existing nodes in the zone
    current_row_y = min(n['y'] for n in inside)
    return next_x, current_row_y

ID Generation

Read the canvas, collect all existing IDs. Never reuse one.

Safe ID pattern: [type]-[content-slug]-[full-unix-timestamp]

Use the full Unix timestamp (10 digits) to avoid collisions in batch operations.

Examples: img-cover-1744032823, text-note-1744032845, zone-branding-1744032901

If a collision is detected (ID already exists in the canvas), append -2, -3, etc.

Session Log (optional hook)

If wiki/canvases/.recent-images.txt exists, append any new image path written to _attachments/images/ during this session (one path per line, keep last 20).

/canvas from banana reads this file first, making it instant without filesystem search.

Banana Integration (if the banana-claude plugin is installed)

After any /banana run in the same session, if the user says "add to canvas" or "put on canvas", treat it as /canvas from banana.

When /banana finishes generating images, suggest:

"Add generated images to canvas? Run /canvas from banana"

Summary

1. Read canvas-spec.md before editing any canvas JSON.
2. Always read the canvas file before writing. Parse existing nodes to avoid ID collisions and calculate auto-positions.
3. Create _attachments/images/canvas/ for downloaded/copied images.
4. Update wiki/index.md when creating new canvases.
5. Report position and zone after every add operation.

See Also

For standalone visual production (12 templates, 6 layout algorithms, AI generation, presentations), see claude-canvas. This skill handles wiki-scoped visual boards. claude-canvas handles full-featured canvas orchestration for any project.

How to think (10-principle mapping)

When working on this skill, apply the 10-principle loop. See skills/think/SKILL.md for the canonical framework.