Backend for the TRMNL screenshot plugin. TRMNL points at /display and screenshots it onto its 800×480 e-ink panel. Friends and family upload images at /; the most recent upload is what shows on the wall.

Route	Purpose
GET /	Upload form (email required, image required, caption optional).
POST /upload	Stores the processed image, caption, and uploader record.
GET /image	Serves the current image as binary image/png.
GET /display	The page TRMNL screenshots — image at 800×480 with optional caption bar. Public link to share with TRMNL.
GET /admin	HTTP Basic auth (admin / ADMIN_PASSWORD). Lists every uploader with upload count, last upload, reminder state.
GET /admin/test-email?to=...	Sends one reminder email to the given address. No state changes.
GET /admin/run-cron	Manually triggers the reminder cron. Supports ?dry=1 (don't send/persist) and ?days_ahead=N (simulate future time). Returns JSON summary.
GET /opt-out?email=...	Flips reminders to false for an email. Linked from reminder emails.

Public URL: https://joshbeckman--b073704c405011f19b9c42b51c65c3df.web.val.run. Friendlier alias for sharing: http://www.joshbeckman.org/frametags/home-trmnl-small.

backend/
  index.ts   # Hono HTTP app (all routes above)
  cron.ts    # Daily reminder job (separate cron trigger in Val Town)
frontend/
  index.html # Upload form
  index.tsx  # Client-side resize + upload (no dithering — TRMNL handles B&W)

Done client-side in frontend/index.tsx:

1. Draw the uploaded image onto an 800×480 canvas, scaled to cover.
2. canvas.toDataURL("image/png") → POST to /upload.

We don't dither to 1-bit ourselves — TRMNL converts the screenshot to B&W on its end, and pre-dithering caused weirdness. We also avoid image-rendering: pixelated on /display for the same reason. The /image endpoint decodes the stored data URL and serves binary PNG so /display references it as a real URL (TRMNL's screenshot pipeline doesn't like huge inline data: URIs).

Key	Shape
trmnl_image_data	{ image: dataUrl, caption: string } — current image only.
trmnl_uploaders	{ [email]: Uploader }

type Uploader = {
  lastUpload: string;        // ISO timestamp
  count: number;             // total uploads
  reminders: boolean;        // opt-in flag, default true
  lastReminded?: string | null;
  reminderCount?: number;    // how many reminders sent in current cycle
}

Uploading resets lastReminded and reminderCount so the cycle starts over.

Runs daily. For each uploader with reminders === true and reminderCount < 4, sends a nudge if enough time has passed. The email body lives in sendReminderEmail() in cron.ts — /admin/test-email calls the same function. Backoff doubles each reminder:

Reminder #	Wait since previous touch
1	14 days (since last upload)
2	28 days
3	56 days
4	112 days
5+	never — silence

Total: at most 4 emails over ~7 months, then we leave them alone. Each email contains an opt-out link.

• ADMIN_PASSWORD — required for /admin. Username is hardcoded to admin.

vt watch     # auto-sync edits to Val Town
vt tail      # stream logs
vt browse    # open in browser