canvas

What this skill does

# 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 oper