Tanban Thunderbird

A Thunderbird Mail Extension that turns your tasks into a visual Kanban board.

Organize tasks by dragging them across columns — To Do, In Progress, Done, Cancelled. Status changes are persisted back to Thunderbird's built-in calendar via custom experiment APIs.

Features

• Renders Thunderbird tasks as draggable Kanban cards
• Four columns: To Do, In Progress, Done, Cancelled
• Drag-and-drop to change task status
• Click any task to open Thunderbird's task editor
• "Create Task" button to add new tasks
• Auto-refresh on task create/update/delete (no manual reload needed)
• Overdue highlighting for past-due tasks
• Dark theme matching Thunderbird's UI

Requirements

• Thunderbird 128.0 – latest

Installation

Temporary (for development)

1. Open Thunderbird and go to about:debugging
2. Click This Thunderbird
3. Click Load Temporary Add-on…
4. Select manifest.json from this project

Permanent (packed extension)

zip -r tanban.zip . -x "*.git*" "*.zip" "AGENTS.md"

Then install the .zip via Thunderbird's Add-ons Manager (gear menu → Install Add-on From File…).

Project Structure

manifest.json            # Extension manifest with 6 experiment_apis
background.js            # Background script — message routing, task CRUD
tanban.html              # Main UI shell
tanban.js                # Frontend — board rendering, drag-and-drop
tanban.css               # Dark-theme stylesheet
icons/                   # Extension icons (16px, 32px SVG/PNG)
calendar/experiments/    # Thunderbird calendar experiment APIs
  calendar/
    ext-calendar-utils.sys.mjs   # Shared utilities (ES module)
    schema/                      # JSON API schemas
    parent/                      # Parent-process implementations
    child/                       # Child-process implementations

Architecture

The extension has three layers:

1. Frontend (tanban.js) — renders the board in a tab, manages drag-and-drop, sends messages to the background script
2. Background script (background.js) — listens for messages from the frontend, proxies requests to calendar APIs, forwards real-time change events back to the frontend
3. Experiment APIs (calendar/experiments/) — six Thunderbird-specific APIs that bridge WebExtension code to Mozilla's internal calendar services (calUtils, CalEvent, CalTodo, etc.)

Communication flow

Frontend (tanban.js)
  │  browser.runtime.sendMessage({ action: "getTasks" })
  ▼
Background (background.js)
  │  browser.calendar.items.query({ type: "task" })
  ▼
Experiment API (ext-calendar-items.js)
  │  cal.manager.getCalendars() → calendar.getItemsAsArray()
  ▼
Thunderbird's calendar storage

Calendar changes (create/update/delete) are pushed back in real time via browser.calendar.items.onCreated/onUpdated/onRemoved events.

Development

Quick reload

Changes to tanban.js, tanban.css, tanban.html, or background.js take effect after refreshing the Tanban tab (Ctrl+Shift+F5 or the Refresh Tasks button).

Full restart required

Changes to files under calendar/experiments/ require a Thunderbird restart — experiment APIs are loaded at startup and do not hot-reload.

API Reference

The extension exposes the following custom browser APIs (via manifest.json experiment_apis):

Namespace	Schema	Description
browser.calendar.calendars	calendar-calendars.json	Query, create, update, remove calendars
browser.calendar.items	calendar-items.json	Query, create, update, move, remove tasks/events
browser.calendar.provider	calendar-provider.json	Register custom calendar providers
browser.calendar.timezones	calendar-timezones.json	Query timezone data
browser.calendarItemAction	calendarItemAction.json	Toolbar buttons in event dialogs
browser.calendarItemDetails	calendarItemDetails.json	Custom panels in event details view

License

GNU General Public License v3.0. See LICENSE.