personal-wiki/skills/canvas/SKILL.md

---
name: canvas
description: >
  Visual layer of the wiki. Add images, text cards, PDFs, and wiki pages to Obsidian
  canvas files. Auto-positions nodes inside zones using bbox math. Integrates with
  /banana skill for generated 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", "Bash", "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.

---

## 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/index.md` under a "## Canvases" section (create the section if it doesn't exist).
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]`.
- 16:9 (width/height ≈ 1.7–2.0): width=420, height=236
- 1:1 (ratio ≈ 1.0): width=280, height=280
- 9:16 (ratio < 0.65): width=200, height=356
- Unknown: width=320, height=240

**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.
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 -140 if no nodes.
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`)

1. Check `wiki/canvases/.recent-images.txt` first (session log of newly written images).
2. If not found or empty: `find _attachments/images -name "*.png" -o -name "*.jpg" -newer [10min-ago-file]`
   Create the reference file: `python3 -c "import time; open('/tmp/ten-min-ago','w').close(); import os; os.utime('/tmp/ten-min-ago', (time.time()-600, time.time()-600))"`
   Then: `find _attachments/images -newer /tmp/ten-min-ago -name "*.png" -o -name "*.jpg"`
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 — match the top y of existing row
    current_row_y = min(n['y'] for n in inside if n['x'] > zx + zw / 2) \
                    if any(n['x'] > zx + zw / 2 for n in inside) \
                    else zy + 20
    return next_x, current_row_y
```

---

## ID Generation

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

Safe ID pattern: `[type]-[content-slug]-[unix-timestamp-last-4-digits]`

Examples: `img-cover-7823`, `text-note-1045`, `zone-branding-3391`

---

## 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

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.