# Markloom Agent Guide

Markloom is a static visual review board. Use it when a user wants to compare screenshots, generated mockups, goldens, simulator captures, or reference images, then mark exact visual fixes.

Always re-read this guide before using Markloom. The board and skill may change without breaking the URL, and this page is the current source of truth.

## Quick Start

Open:

```text
https://markloom.satoapps.com/board/
```

To preload images, pass a base64url JSON payload in the hash:

```text
https://markloom.satoapps.com/board/#data=<base64url(JSON)>
```

Payload:

```json
{
  "title": "UI Review",
  "storageKey": "ui-review-20260605",
  "pairs": [
    {
      "id": "home",
      "title": "Home Screen",
      "left": "https://example.com/mock.png",
      "right": "https://example.com/golden.png",
      "leftLabel": "Mock",
      "rightLabel": "Golden"
    }
  ]
}
```

Supported pair fields:

- `id`: stable board id
- `title`: section title
- `left` or `mock`: left image URL or data URL
- `right` or `golden`: right image URL or data URL
- `leftLabel`: left image label
- `rightLabel`: right image label
- `leftAlt`: optional left image alt text
- `rightAlt`: optional right image alt text

Do not inject red or blue review comments, handwritten annotations, arrows, or boxes through the import payload. The import payload should only define page title, section title, image URLs, and image labels. The user or agent should add visual annotations on the board after import.

## Tools

The board exposes:

- Select
- Pen
- Arrow
- Box
- Eraser
- Add image
- Color swatches
- Board-level Undo, Redo, Reset, and Copy

There is no circle tool.

## Clipboard

Use the board-level `Copy` button to copy the rendered board image to the clipboard. This is the preferred handoff back to an LLM or another review thread.

## Updating Images

To update one image, decode the current `#data` payload, replace the target pair's `left` or `right`, then re-encode and update the hash. Keep the same `storageKey` and `id` if existing annotations should stay associated with the same review. Use a new `storageKey` if the board should open clean.

## Large Images

Small HTTPS URLs and small data URLs are fine in hash payloads. For large images, prefer opening the board and pasting or dragging images into it.

## Downloadable Skill

The current skill is available at:

```text
https://markloom.satoapps.com/skill/SKILL.md
```

If an agent has a local copy, it should refresh it after Markloom updates. If an agent is unsure how the board works, it should read this guide and the skill URL again instead of relying on stale instructions.