moss-canvas

Moss Canvas

Canvas is a rough editable spatial surface, not a text-diagram renderer.

Creation Authority

• Preserve and edit an existing moss-canvas block when the task requires it.
• Create a new canvas when the user asks for canvas or explicitly requests an editable spatial diagram.
• For a generic diagram, flow, wireframe, menu, or option sketch, use a fenced ASCII code block instead.
• Use an image for a polished static visual, a chart for quantitative shape, and HTML only for genuine interaction.

Use canvas when relative position, connectors, and rough shapes matter more than readable text in the grid. Grid characters become ink; readable words must be label metadata.

Fence And Payload

Create new blocks with moss-canvas. Preserve existing legacy moss-sketch fences rather than renaming them incidentally.

```moss-canvas
[moss:grid:v2]
[moss:labels:[{"id":"research","text":"Research","col":8,"row":4}]]
....########................................
....#......#................................
....########................................
```

This is a complete valid input. Moss accepts up to 60 grid rows of up to 120 characters, pads missing cells as empty, truncates excess cells, and normalizes a saved canvas to exactly 120 columns by 60 rows.

Payload order:

1. [moss:grid:v2].
2. Optional single-line [moss:labels:<JSON array>].
3. Grid rows.

Grid rules:

• . and spaces are empty.
• Every other character becomes filled ink; letters and box-drawing glyphs do not remain readable text.
• Coordinates are zero-based: columns 0-119, rows 0-59.
• Keep drawings sparse and labels clear of strokes.

Each label object requires:

Field	Contract
id	Unique non-empty string within the canvas.
text	Non-empty string; keep it under 80 characters.
col	Integer from 0 through 119.
row	Integer from 0 through 59.

Use valid compact JSON on the metadata line. Do not duplicate label IDs or rely on malformed label objects being repaired.