Reviewing Diffs on E-Ink Devices

When you have background coding agents working on your codebase — tools like kimaki (runs Claude Code / OpenCode sessions from Discord threads), clawdbot (self-hosted AI assistant that connects to Discord, Slack, Telegram, and more), or any other agent-based workflow — you often want to review their changes without sitting at a computer.

Critique can generate PDFs from diffs and AI-powered reviews with full syntax highlighting and diff formatting. Send the PDF to a Kindle or Boox e-reader and review agent work from your couch, bed, or commute.

The typical flow:

1. An agent makes changes to your codebase (via kimaki, clawdbot, Claude Code, etc.)
2. You run critique review --pdf to generate an AI-explained review as a PDF
3. You send the PDF to your e-reader (email, cloud sync, or drag-and-drop)
4. You unlock the device and read the review with syntax-highlighted diffs and explanations

Generate a PDF

# Diff as PDF
critique --pdf
critique --pdf my-diff.pdf
critique main --pdf

# AI review as PDF
critique review --pdf
critique review main --pdf --agent claude

# Auto-open after generating
critique --pdf --open
critique review --pdf --open

The PDF is saved to /tmp/ by default. Pass a filename to control the output path.

Send to Kindle

All methods below require a one-time setup: find your Kindle email at https://amazon.com/mycd → Devices → select your Kindle. Then add your sending email to the approved list under Preferences → Personal Document Settings.

zele (recommended, Gmail OAuth)

zele is a Gmail CLI that authenticates via OAuth — no SMTP passwords or app passwords needed. One-time zele login, then send emails from the command line.

bun install -g zele

# One-time: authenticate with Google
zele login

# Send the PDF to your Kindle
critique review main --pdf /tmp/review.pdf

zele mail send \
  --to yourname@kindle.com \
  --subject "convert" \
  --body "Agent review" \
  --attach /tmp/review.pdf

Put "convert" in the subject to reflow text with adjustable fonts. Without it, the PDF renders as-is (fixed layout, which actually works well for diffs since it preserves code formatting).

Send to Kindle web (manual)

If you don't need automation:

1. Go to https://amazon.com/sendtokindle
2. Drag and drop the PDF
3. Select your device

Send to Boox

Syncthing (recommended, fully programmatic)

Syncthing auto-syncs a folder between your computer and Boox over the local network. No IP addresses to remember, no USB, no internet required — just same Wi-Fi. Self-hosted and end-to-end encrypted.

One-time setup:

1. Install Syncthing on your computer (brew install syncthing on macOS)
2. Install Syncthing on the Boox from the Boox Play Store (search "Syncthing")
3. Exchange device IDs between the two
4. Create a shared folder (e.g. ~/Syncthing/boox-reviews ↔ /sdcard/Syncthing/boox-reviews)
5. Disable battery optimization for Syncthing on the Boox so it syncs in the background

Then forever after:

critique review main --pdf ~/Syncthing/boox-reviews/review.pdf
# done — appears on the Boox automatically

Google Drive / Dropbox sync (alternative, needs internet)

Set up cloud sync on your Boox (Settings → Accounts → Google Drive or Dropbox), then save the PDF directly to the synced folder:

critique review main --pdf ~/Google\ Drive/critique-reviews/review.pdf

Same idea as Syncthing but goes through the cloud instead of local network.

adb push (alternative, needs IP or USB)

Boox runs Android, so adb push works for fully scripted transfers. Requires either a USB cable or knowing the device IP.

# USB
adb push /tmp/review.pdf /sdcard/Download/

# Wi-Fi (Android 11+: pair once via Settings → Developer Options → Wireless debugging)
adb pair 192.168.1.x:45678    # enter pairing code
adb connect 192.168.1.x:34567
adb push /tmp/review.pdf /sdcard/Download/

Send2Boox (manual, works remotely)

1. Go to https://push.boox.com
2. Log in with your Boox account
3. Upload the PDF — it syncs to your device

Scripted Workflows

One-liner to generate a review and email to Kindle:

critique review main --pdf /tmp/review.pdf && \
  zele mail send \
    --to yourname@kindle.com \
    --subject "convert" \
    --body "Agent review" \
    --attach /tmp/review.pdf

With swaks (works today):

critique review main --pdf /tmp/review.pdf && \
  swaks --to yourname@kindle.com \
        --from you@gmail.com \
        --server smtp.gmail.com:587 --tls \
        --auth-user you@gmail.com \
        --auth-password "your-app-password" \
        --header "Subject: convert" \
        --body "Agent review" \
        --attach /tmp/review.pdf

For Boox with Syncthing:

critique review main --pdf ~/Syncthing/boox-reviews/review-$(date +%Y%m%d).pdf

Web Preview Alternative

If you prefer reading in a browser on your e-reader instead of PDF:

critique review main --web
# Outputs a URL like https://critique.work/v/abc123

Open that URL in the Boox browser or Kindle's experimental browser. The web preview auto-detects mobile viewports and serves a unified diff view optimized for smaller screens.

Quick Reference

What	Command	Programmatic?
Diff → PDF	critique --pdf	Yes
Review → PDF	critique review --pdf	Yes
Send to Kindle	zele mail send --to ...@kindle.com --attach file.pdf	Yes
Send to Boox	Save to Syncthing shared folder	Yes
Diff → web link	critique --web	Yes
Review → web link	critique review --web	Yes
Specific commit	critique --commit abc123 --pdf	Yes
Branch comparison	critique main feature --pdf	Yes
With session context	critique review --session <id> --pdf	Yes