---
name: canvas
description: "Visual layer of the wiki. Add images, text cards, PDFs, and wiki pages to Obsidian canvas files with auto-positioning inside zones. Integrates with /banana for image capture. Triggers on: /canvas, canvas new, canvas add image, canvas add text, canvas add pdf, canvas add note, canvas zone, canvas list, canvas from banana, add to canvas, put this on the canvas, open canvas, create canvas."
allowed-tools: Read Write Edit Glob Grep
---

# 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](https://jsoncanvas.org/).

**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:

```json
{
  "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]"
3. If no: create it with the starter structure above.
   Report: "Created main.canvas with a General zone."
4. 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:
```json
{
  "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.
3. Create a file node: width=300, height=100.
4. Position using auto-layout.

```json
{
  "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:

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

---

## Auto-Positioning Algorithm

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

```python
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](https://github.com/AgriciDaniel/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`](../think/SKILL.md) for the canonical framework.

| # | Principle | Application here |
|---|-----------|-------------------|
| 1 | OBSERVE (ext) | Which images, PDFs, notes belong on this canvas? Read each before adding. |
| 2 | OBSERVE (int) | Am I aestheticizing or actually communicating? Pretty canvases that don't inform are noise. |
| 3 | LISTEN | The user's mental model of how these items relate. The canvas should mirror that, not impose another. |
| 4 | THINK | Layout, group hierarchy, edge structure. Spatial reasoning matters; arbitrary positions confuse. |
| 5 | CONNECT (lat) | Edges between canvas nodes reveal hidden structure not visible in the linear wiki. |
| 6 | CONNECT (sys) | JSON Canvas 1.0 spec + Obsidian-native rendering + banana skill for AI image gen. |
| 7 | FEEL | A canvas should be readable at first glance, not a maze of arrows. |
| 8 | ACCEPT | Not every project needs a canvas. Admit when prose is enough. |
| 9 | CREATE | Write the `.canvas` JSON with stable IDs and sensible positions. |
| 10 | GROW | Which canvases get reopened? Which are abandoned? That signal informs canvas-worthiness over time. |
