---
title: Data flow - SMT Beacon, one leaf for each Beacon Signal
config:
  flowchart:
    nodeSpacing: 20
    rankSpacing: 30
---

%% Technical version of the hand sketch "btcr2 data flow visualization".
%% Sketch element → diagram element:
%%   smiley at the left → Stuart; smiley with a top hat at the right → Satoshi
%%   "Agg" with three small faces → Aggregation Service
%%   cloud with a tree, "search by did", "Map" → SMT: the leaf index of a DID is hash(did)
%%   "k/n", "signed? yes" → the cohort signs: all n (n-of-n), or k of n (k-of-n fallback)
%%   tower → SMT Beacon
%%   "Sidecar" stack → Sidecar Data
%%   bar with cells and dots → Bitcoin blocks with Beacon Signals
%%   "Q", "inclusion, non-inclusion, gibberish", tall box with 3 parts → the 3 states of the leaf of Stuart
%%   faces under the bar → the leaf state for each Beacon Signal
%%   stars, papers, "K1" → the update of Stuart (detail on the key rotation page)
%%   crossed-out figure → not used

flowchart TD
    classDef chain fill:#fff1dd,stroke:#f7931a,stroke-width:2px,color:#4a2a00
    classDef agg fill:#efe7fb,stroke:#7e57c2,stroke-width:2px,color:#2e1a4f
    classDef sidecar fill:#e3f4e6,stroke:#2e7d32,stroke-width:2px,color:#123d17
    classDef ok fill:#e3f4e6,stroke:#2e7d32,color:#123d17
    classDef none fill:#f4f4f4,stroke:#777777,color:#333333
    classDef bad fill:#fdecea,stroke:#b3261e,color:#7a1d15

    Stuart(["Stuart<br/>🧾 update: new key"])
    Agg["🤝 Aggregation Service"]:::agg
    SMT@{ shape: cloud, label: "🌲 SMT<br/>leaf at hash(did)" }
    class SMT agg
    Beacon["🏷 SMT Beacon"]:::chain
    Sidecar[("🧳 Sidecar Data")]:::sidecar
    Satoshi(["Satoshi's resolver"])

    subgraph Chain["⛓ Bitcoin blocks"]
      direction LR
      B1["✓"]:::ok --- B2["–"]:::none --- B3["✓ new key"]:::ok --- B4["○"]:::none --- B5["✗"]:::bad
    end

    subgraph Q["Q: the leaf of Stuart"]
      direction TB
      Inclusion["✓ inclusion: apply the update"]:::ok
      NonInclusion["○ non-inclusion: no update"]:::none
      Gibberish["✗ gibberish: DID invalid"]:::bad
      Inclusion ~~~ NonInclusion ~~~ Gibberish
    end

    Stuart -->|"🔖 leaf value"| Agg
    Agg --> SMT
    SMT -->|"signed? yes<br/>n of n, or k of n"| Beacon
    Beacon -->|"⛓ SMT root"| Chain
    Stuart -.->|"🧾 update,<br/>🌲 SMT Proofs"| Sidecar
    Sidecar -.-> Satoshi
    Chain --> Satoshi
    Satoshi --> Q