Chains

Overview

A chain gives a follower read-only access to a card. The card owner sends a chain request to a follower, granting that person access to the card's public information. The recipient can accept or decline. If accepted, the card appears in the recipient's collection as a view-only record — they can see everything on the front of the card, but they do not own the card and cannot edit it. An accepted chain can be passed further down: the recipient may re-chain the same card to their own followers, creating a branching tree of access. Removing any link in that tree immediately cuts off everyone downstream.

---

Fields

Field	What it represents
From	The user who sent the chain request
To	The user who received the chain request
Card	The card this chain gives access to
Start date	Optional date from which the chain becomes active
End date	Optional date after which the chain expires
Accepted	Whether the recipient has accepted the chain request
Parent chain	The chain one level up in the chain hierarchy; empty for a root chain sent directly by the card owner

---

Relations

• Notifications

Business Rules

1. A card owner may chain any of their cards to a follower.
2. The recipient can see the card's front (public) information before deciding — private back-card data is never exposed.
3. The recipient may accept or decline the chain request.
4. If declined, the chain is cancelled and the recipient loses all visibility of that card.
5. If accepted, the card appears in the recipient's "Chains accepted with me" view as a read-only record showing front-card information only.
6. An accepted chain can be re-chained to the recipient's own followers, creating a tree of chained access.
7. A user who holds a chained card does not own it and cannot edit it.
8. If any node in the tree removes their chain, every downstream node immediately loses access — the removal cascades to the full subtree beneath that node.
9. If the card owner removes the root chain, every node in the entire tree loses access at once.
10. Creating a chain has a coin cost. If the sender has insufficient coins, the chain is not created. See Coins.
11. The same card cannot be chained twice to the same recipient by the same sender.
12. If an end date is set and that date passes, the chain expires and access is revoked.

---

States

State	Meaning
Pending	The chain request has been sent; the recipient has not yet responded
Accepted	The recipient accepted; the card is visible in their chains view
Declined / Removed	The chain was refused by the recipient or deleted by either party; no access remains

---

Constraints

• A card is required; a chain cannot exist without one.
• Duplicate chains — same card, same sender, same recipient — are rejected.
• The card's chain count is incremented when a chain is created and decremented when it is removed or expires. It cannot fall below zero.