Rails Markup

Point-and-click annotation tool for Rails apps. Click any element, describe what needs to change, and your AI agent reads and acts on your feedback via MCP.

v1.0 — Author attribution, export, search, screenshots with drawing tools, kanban board, notification hooks.

How it works

1. Install the gem — adds migration, toolbar, auth controller, and routes
2. Open your app — the annotation toolbar appears as a floating button
3. Click any element — hover to highlight, click to annotate with screenshots
4. Draw on screenshots — arrows, rectangles, highlights on captured elements
5. Agent reads it — AI calls rails_markup_read via MCP
6. Agent fixes it — resolves the annotation and moves on

Install

# Gemfile
gem "rails-markup", github: "inventlist/rails-markup", require: "rails_markup"

bundle install
rails generate rails_markup:install
rails db:migrate

When upgrading an existing installation, copy and run new engine migrations:

bin/rails railties:install:migrations FROM=rails_markup
bin/rails db:migrate

Rails Markup 1.2 rolling UUID upgrade

The 1.2 upgrade migration adds, repairs, and uniquely indexes client_uuid, but deliberately leaves the column nullable while old application instances may still be serving traffic. Fresh installs create it as NOT NULL immediately.

For a rolling upgrade:

1. Run the copied migrations and deploy 1.2 to every application instance.
2. Wait until all old pre-1.2 instances are drained and have stopped.
3. Repair any rows written during the mixed-version window, then verify:

bin/rails rails_markup:client_uuids:repair
bin/rails rails_markup:client_uuids:verify

Both commands are safe to repeat. A pull containing any lingering blank or noncanonical identity returns 503 without mutating data. Do not add a NOT NULL constraint until verification stays green after old instances are drained; that explicit contract migration belongs in a later release.

The generator creates:

File	Purpose
db/migrate/*_create_rails_markup_annotations.rb	Annotations table
config/initializers/rails_markup.rb	Configuration
app/controllers/rails_markup_auth_controller.rb	Auth controller
bin/markup	CLI wrapper
Route mount	Engine at /admin/annotations
Toolbar injection	<%= render "rails_markup/shared/toolbar" %> in your layout

Generator options

rails generate rails_markup:install \
  --mount-path=/admin/annotations \
  --base-controller=Admin::BaseController \
  --layout=application

Authentication and browser synchronization

The generated RailsMarkupAuthController protects both the mounted dashboard and the toolbar API. It denies access unless current_user.admin? is true; customize authorize_rails_markup! if your host uses another authorization policy. The configured base controller must actually enforce authorization. Choosing a public controller makes both interfaces public.

The toolbar uses the same host authentication boundary as the dashboard and sends normal Rails CSRF tokens on every mutation. Keep csrf_meta_tags in the host layout. Rails is authoritative; localStorage is an offline cache and a durable desired-state outbox, keyed by a client UUID.

During reconciliation, browser-owned content, intent, severity, selection, target, permitted metadata, and an explicitly dirty status remain local until a successful UUID PUT. Server-owned thread, author/user identity, and timestamps always win. A complete exact-page pull may remove a synced local record absent from Rails, but never removes pending upserts or delete tombstones.

Uninstall

rails generate rails_markup:uninstall
# Add --remove-migration to also delete the migration file

Configuration

# config/initializers/rails_markup.rb
RailsMarkup.configure do |config|
  # Auth controller for dashboard and toolbar API; it must authorize access.
  config.base_controller_class = "RailsMarkupAuthController"

  # External API token (for MCP production tools)
  config.api_token = Rails.application.credentials.dig(:rails_markup, :api_token)

  # Author display name from current_user
  config.author_name_method = :name
  # Or use a Proc:
  # config.author_name_method = ->(user) { "#{user.first_name} #{user.last_name}" }

  # Callback fired after each annotation is created
  config.on_create_callback = ->(annotation) {
    SlackNotifier.notify("Feedback on #{annotation.page_url}: #{annotation.content}")
  }

  # Toolbar accent color: indigo, amber, blue, emerald, rose
  config.toolbar_accent = "indigo"

  # Show or hide the annotation toolbar and FAB (default: true)
  config.toolbar_enabled = true

  # FAB corner: bl, br, tl, tr; size: slim, compact, default
  config.toolbar_position = "bl"
  config.toolbar_size = "default"

  # Element screenshots (default: true)
  config.enable_screenshots = true

  # Dashboard pagination (default: 25)
  config.per_page = 25

  # "Back to app" link
  config.return_url = "/admin"
end

Dashboard

Visit /admin/annotations for the full dashboard:

• List view — status filters, search, author filter, load-more pagination
• Board view — kanban with drag-and-drop status transitions
• Export — CSV and JSON downloads (respects current filters)
• Detail panel — full content, metadata, screenshots, thread
• Bulk actions — dismiss all pending/acknowledged

Search & Filters

• Text search — searches annotation content and selected text
• Author filter — filter by who created the annotation
• Page URL filter — filter by annotated page
• Status pills — pending, acknowledged, resolved, dismissed

Screenshots & Drawing

When you click an element, the toolbar captures a screenshot using SVG foreignObject. Before submitting, you can draw on it:

• Arrow — click and drag to draw red arrows
• Rectangle — click and drag for red outline boxes
• Highlight — freehand semi-transparent yellow strokes
• Undo — remove the last drawing operation

Screenshots are stored as base64 in annotation metadata and displayed in the dashboard detail view.

CLI

# Setup
bin/markup init                        # Interactive setup wizard (TUI)
bin/markup configure                   # Set .mcp.json env vars
bin/markup status                      # Show config (tokens masked)
bin/markup setup-production --url=URL  # Generate token + configure

# Server
bin/markup server                      # HTTP + MCP server
bin/markup mcp                         # MCP-only server (stdio)

# Annotations (match MCP tool verbs)
bin/markup pending                     # Fetch pending from dev
bin/markup pending --production        # Fetch from production
bin/markup resolve 42 --summary "..."  # Resolve an annotation
bin/markup dismiss 42 --reason "..."   # Dismiss an annotation
bin/markup reply 42 "message"          # Reply to an annotation
bin/markup acknowledge 42              # Mark as acknowledged
bin/markup watch                       # Poll for new annotations
bin/markup watch --production          # Watch production

# Info
bin/markup sessions                    # Session info (MCP only)
bin/markup session ID                  # Session detail (MCP only)

Setup Wizard

Run bin/markup init for an interactive setup that walks you through:

1. Toolbar accent color (indigo, amber, blue, emerald, rose)
2. Toolbar position (bottom-left, bottom-right, top-left, top-right)
3. Toolbar size (slim, compact, default)
4. Screenshot capture (on/off)
5. Production URL (optional)

Writes config/initializers/rails_markup.rb and updates .mcp.json automatically.

MCP Setup

Add to .mcp.json:

{
  "mcpServers": {
    "rails-markup": {
      "type": "stdio",
      "command": "ruby",
      "args": ["bin/markup", "mcp"],
      "env": {
        "RAILS_MARKUP_DEV_URL": "http://localhost:3000",
        "RAILS_MARKUP_PROD_URL": "https://yourapp.com",
        "RAILS_MARKUP_PROD_TOKEN": "your-prod-api-token"
      }
    }
  }
}

MCP tools (five canonical thin-enum tools)

The MCP server advertises exactly five tools. Their schemas reject unknown arguments and use small enums instead of multiplying environment-specific tool names:

Tool	Contract
rails_markup_read	Read pending, sessions, session, or annotation; never acknowledges
rails_markup_watch	Watch development annotations with bounded timeout/window
rails_markup_transition	acknowledge or resolve an annotation
rails_markup_reply	Add an agent reply
rails_markup_dismiss	Destructively dismiss with a reason

environment is development or production where supported. Production URL and bearer credentials come only from trusted process configuration. Caller-supplied URL and token overrides are rejected and are never forwarded.

Legacy MCP compatibility

Legacy names remain hidden but callable as explicit, warning-emitting adapters during the 1.2/1.3 compatibility window. They never restore caller-controlled credentials or mutating reads. They will be removed after 1.3.0; migrate clients to the five canonical tools above.

Annotation Data

Each annotation includes:

• Content — what needs to change (max 5000 chars)
• CSS selector — div#hero.max-w-xl
• CSS path — body > main > div:nth-of-type(2) > div#hero
• Bounding box — { top, left, width, height }
• Nearby text — first 80 chars of element text
• Selected text — highlighted text before clicking
• Screenshot — element capture with optional drawings
• Author — who created it (via author_name_method)
• Intent — fix, change, question, or approve
• Severity — suggestion, important, or blocking

Architecture

Browser Toolbar                    AI Agent (Claude Code, Cursor)
    |                                    |
    | Authenticated same-origin API      | MCP (stdio JSON-RPC)
    | (pull + UUID PUT/DELETE, CSRF)     | or CLI (bin/markup pending)
    v                                    v
+----------------------------------------------------------+
|                  Rails Engine                             |
|                                                          |
|  Toolbar     →  Annotations    →  Dashboard              |
|  (vanilla JS)   (ActiveRecord)    (list + board views)   |
|                       ↑                                  |
|              External API (/external/*)                   |
|              (token-authenticated, used by MCP)           |
+----------------------------------------------------------+

Development

git clone https://github.com/inventlist/rails-markup
cd rails-markup && bundle install
bundle exec ruby -Ilib:test test/**/*_test.rb

License

MIT. See LICENSE.