pzp-set/protospec.md

Feed tangle

(Lipmaa backlinks are not shown in the diagram below, but they should exist)

graph RL

R["(Feed root)"]
A[adds alice]
B[adds bob]
C[deletes alices]
D[adds bob]
E[adds carol]

C-->B-->A-->R
D--->A
E-->D & C
classDef default fill:#bbb,stroke:#fff0,color:#000

Reducing the tangle above in a topological sort allows you to build an array (a JSON object) [bob, carol].

Msg type

msg.metadata.type MUST start with set_v1__. E.g. set_v1__follows.

Msg content

msg.content format:

interface MsgData {
  add: Array<string>,
  del: Array<string>,
  supersedes: Array<MsgID>,
}

Supersedes links

When you add or delete an item in a set, in the supersedes array you MUST point to the currently-known highest-depth msg that added or deleted that item.

Also, when you add any item, in the supersedes array you SHOULD point to all currently-known highest-depth msgs that deleted something.

The set of not-transitively-superseded-by-anyone msgs comprise the "item roots" of the record. To allow pruning the tangle, we can delete (or, if we want to keep metadata, "erase") all msgs preceding the item roots.

Suppose the tangle is grown in the order below, then the field roots are highlighted in blue.

graph RL

R["(Feed root)"]
A[adds alice]:::blue

A-->R
classDef default fill:#bbb,stroke:#fff0,color:#000
classDef blue fill:#6af,stroke:#fff0,color:#000

---

graph RL

R["(Feed root)"]
A[adds alice]:::blue
B[adds bob]:::blue

B-->A-->R
classDef default fill:#bbb,stroke:#fff0,color:#000
classDef blue fill:#6af,stroke:#fff0,color:#000

---

graph RL

R["(Feed root)"]
A[adds alice]
B[adds bob]:::blue
C[deletes alices]:::blue

C-->B-->A-->R
C-- supersedes -->A

linkStyle 3 stroke-width:1px,stroke:#05f
classDef default fill:#bbb,stroke:#fff0,color:#000
classDef blue fill:#6af,stroke:#fff0,color:#000

---

graph RL

R["(Feed root)"]
A[adds alice]
B[adds bob]:::blue
C[deletes alices]:::blue
D[adds bob]:::blue

C-->B-->A-->R
C-- supersedes -->A
D--->A

linkStyle 3 stroke-width:1px,stroke:#05f
classDef default fill:#bbb,stroke:#fff0,color:#000
classDef blue fill:#6af,stroke:#fff0,color:#000

---

graph RL

R["(Feed root)"]
A[adds alice]
B[adds bob]:::blue
C[deletes alices]
D[adds bob]:::blue
E[adds carol]:::blue

C-->B-->A-->R
C-- supersedes -->A
D--->A
E-->D & C
E-- supersedes -->C

linkStyle 3,7 stroke-width:1px,stroke:#05f
classDef default fill:#bbb,stroke:#fff0,color:#000
classDef blue fill:#6af,stroke:#fff0,color:#000