[PLUGIN] Send to reMarkable v1.0.0

[Dkoepsell]

Sends selected books from your Calibre library directly to your reMarkable tablet via the cloud. No USB cable, no shared Wi-Fi, no desktop app required.
Features

• []One-click send from the main toolbar
  []Non-EPUB formats (PDF, MOBI, etc.) are auto-converted using Calibre's built-in converter before sending
  []Uses reMarkable's current sync15 cloud API — works with rM1 and rM2
  []Device token stored locally in Calibre's config; never leaves your machine except to authenticate with reMarkable's servers
• Progress dialog with per-book status and cancel support

Requirements

• []Calibre 5.0+
  []A reMarkable account (free tier is fine — no Connect subscription needed)

Installation

1. []Download the ZIP from the link below
   []In Calibre: Preferences → Plugins → Load plugin from file → select the ZIP
   []Restart Calibre
   []Add the button to your toolbar: Preferences → Toolbars & Menus → Main Toolbar

First-time setup (do this once)

1. []Log into my.remarkable.com
   []Go to my.remarkable.com/device/browser/connect — you'll see an 8-character one-time code
   []In Calibre: Preferences → Plugins → Send to reMarkable → Customize
   []Paste the code and click Register Device

Important: Each one-time code is consumed on use whether registration succeeds or fails. If something goes wrong, go back and generate a fresh code before retrying.
After that, just select books and hit the toolbar button. Books land in the root of your reMarkable library under their Calibre title.
Technical notes (for the curious)
The plugin talks directly to reMarkable's sync15 API endpoints:

• []Registration + auth: webapp-prod.cloud.remarkable.engineering
  []Upload: internal.cloud.remarkable.com/doc/v2/files

One implementation detail worth mentioning: the plugin uses Python's http.client directly rather than urllib, because urllib silently converts POST to GET when following HTTP redirects — which causes 405 errors from reMarkable's API. Something to be aware of if you're building your own reMarkable tools in Python.
Known limitations

• []Books always go to the root folder — no collection targeting yet
  []No duplicate detection — sending the same book twice creates two copies
• reMarkable's API is unofficial/reverse-engineered and could change without notice

Download

Source and issue tracker: https://github.com/dkoepsell/SendToRemarkable-Calibre/ (repo link here)
Happy to take bug reports and feature requests in this thread. The most useful thing you can paste if something goes wrong is the exact error text from the dialog — it includes the HTTP status and response body.