Physical Crumbs — Attestation You Can Tap
draft first cut, 2026-09-13.
Everything else in this book is architecture. This chapter is a thing that works today: tap a physical object, log in with your own handle, and it joins your own trail.
Get early access
This is genuinely pre-alpha — built over one weekend, and one real
crumb has been anchored with it end to end. That’s exactly why the
facilitator tooling (the print-sheet generator, the single-anchor tool)
isn’t linked here: it’s not ready to hand to strangers yet. Leave a
handle or email at
breadcrumbs.run/interest
and we’ll reach out directly as it matures, rather than leave working-
but-unpolished tools open to anyone who finds the link. When someone
does tap a real crumb, the flow itself is real: a QR code points at
/anchor/<id>, and logging in is your own AT Protocol handle (Bluesky,
a self-hosted PDS, whatever account you already have) — no
breadcrumbs-owned identity, no password, approve the login on your own
server, done.
Two things share the name “crumb,” on purpose
- Badges —
issuer.breadcrumbs.idattests to someone that they did something (attended an event, completed a station) — not “breadcrumbs” generically, that specific issuer identity. Authority- minted: needs breadcrumbs’ own issuer identity, and is still being built out. - Crumbs — a participant attests to their own trail, anchored to a physical object. Self-minted: the record lives in the tapper’s own repository, never breadcrumbs’. This is the part that’s live — chosen specifically because it needs no issuer at all, so it didn’t have to wait on any authority/identity decision to ship.
The shape of a trail
One physical object anchors a star: every person who taps it before
it’s handed off connects back to the same anchor id. A handoff is a
leap — a received-from / handed-to connection to the previous
holder’s own trail record, the same shape other AT Protocol
“met-in-person” projects (like youandme.at) already proved out for a
single fixed subject, generalized here to any physical object someone
hands to someone else.
Decay depends on what it’s made of
Different materials carry a different “how likely is this actually still around and cared for” prior — a peeled-off sticker decays faster than a pendant worn as a keepsake. The decay math itself doesn’t change; each medium just gets its own window multiplier:
| Medium | Window multiplier | Why |
|---|---|---|
| Sticker | 0.5× | Cheapest, most likely lost or peeled off |
| Card | 1× (baseline) | Handled deliberately, not precious |
| Nail (pushed into a surface) | 1.25× | Anchored at a fixed spot, not carried |
| Magnet | 1.5× | Anchored to a fixed surface, similarly static |
| Laundry tag | 2× | Built for extreme physical durability |
| Pendant | 2.5× | The keepsake tier — kept by intent, not durability |
Real login, not a password stopgap
The first version of this asked for an AT Protocol “app password” — a concept almost nobody outside this ecosystem has heard of, and the actual first real person to try it got stuck on exactly that. It’s since been replaced with real OAuth: type a handle, a live typeahead finds it, and you’re redirected straight to your own server to approve — breadcrumbs never sees a password, or anything else about your account beyond the one record it asks permission to write.
Decoupled from the physical object itself
Printing or writing a tag doesn’t activate anything by default — a facilitator flips an anchor “live” as a separate step, so a whole sheet of QR codes or a box of NFC cards can be produced ahead of time and switched on individually, exactly when and where each one is actually placed.