Sharing a collectible: the affordance that mints a /card link

[maximsan]

Corrected 2 Sep 2026 against prototype/screens.jsx: the “Copy link” stub lives in ShareStreakSheet (line 411, onClick={() => setCopied(true)}), not at line 433.

What to build

A way to share a collectible. There is none today: the app's only share is the streak card, and the Cards tab has no share affordance at all.

This is the surface that makes #171 worth having — until it exists, nothing in the app can produce a /card/<id> link, and the only shareable URL is the marketing / one. The link itself now works; nothing hands one out.

⚠️ Net-new design, not a port

#34's resolution rules this explicitly. The prototype gestures at a link without ever defining one — its share sheet's "Copy link" tile is a stub that sets a flag and copies nothing (the ShareTarget tile in ShareStreakSheet, screens.jsx:411), and the Cards tab has no share entry point whatsoever. So a design pass is owed before a build one, on the same footing as the streak celebration rule from #26.

What #34 already settled

• The payload is an image plus the URL. Render off-screen at a fixed logical size targeting ~1080px and hand it to the iOS system sheet through share_plus — the arrangement Streak surfaces: the streak screen, week strip, freeze tokens and share #26 shipped for the streak card, reused verbatim, with /card/<id> attached alongside.
• The seam exists. SharePresenter (lib/services/share/) is the one thing in front of share_plus; today it offers sharePng only, so carrying a URL is a change to that contract.
• The recipient's experience is not this ticket's — Universal links: the dedicated subdomain, the AASA file, and the card route #171 built it, and ADR-0015 rules it.

Not blocked any more

The link resolves. PR #483 shipped the app half of #171 — /card/<id> opens the app on that card, and an unearned one shows its face. So there is now something at the other end of a link this ticket would mint, and the build can start.

Two things still sit in front of it, and neither is #171's app work:

• The design. No share affordance exists on a collectible anywhere, so where it sits and what it looks like is owed before it is built.
• Real-device proof only. The AASA file on brewpath.maximsan.dev is not served yet (the human step Universal links: the dedicated subdomain, the AASA file, and the card route #171 keeps), so a minted link cannot be tapped end to end until it is. That does not block writing or testing the share.
  The unearned-card question that used to sit here is ruled — ADR-0015: a link shows the card's face and withholds its payload. That is what gives this share an audience, since the recipient has usually not earned what they are sent.

Acceptance criteria

• A collectible can be shared from its sheet, and the share carries both the rendered image and its https://brewpath.maximsan.dev/card/<id> URL
• The share affordance is designed before it is built — where it sits on the sheet and what it looks like, recorded where the ruling can be checked against it
• No widget touches share_plus directly; the SharePresenter seam carries the URL, and a fake asserts both halves of the payload under test