# Reference: Melvin Carvalho's "A Practical Guide to Solid"
> **Author**: Melvin Carvalho
> **Published**: April 2026
> **URL**: <https://melvin.me/public/solid/>
> **Licence**: Published as public educational material on the author's Solid pod.
## Overview
Melvin Carvalho published a 10-part practical guide to the
JavaScript Solid Server (JSS), the upstream reference implementation
that solid-pod-rs ports to Rust. The guide covers the full lifecycle
from pod creation through WAC, authentication, payments, tokens,
multi-chain support, and programmable state anchoring.
This document maps each article to the corresponding solid-pod-rs
module and records implementation parity. For the row-level payment
gap analysis, see [`GAP-ANALYSIS.md` section C.9](../../GAP-ANALYSIS.md#c9-payments-tokens--web-ledgers).
For the row-level parity checklist, see rows 180-195 in
[`PARITY-CHECKLIST.md`](../../PARITY-CHECKLIST.md).
---
## Article Index
### Part 1 — "Your Data, Your Server" (`solid-acl.html`)
**Topic**: JSS installation, pod creation, WAC fundamentals, file
system layout.
**solid-pod-rs mapping**:
| Pod creation + directory scaffold | `provision::provision_pod` | present |
| WAC ACL evaluation | `wac::evaluate_access` | present |
| File system storage | `storage::fs::FileSystemStorage` | present |
| `.acl` sidecar convention | `wac::StorageAclResolver` | present |
All fundamentals covered by the core crate. See GAP-ANALYSIS.md
sections C.1 (LDP) and C.2 (WAC).
---
### Part 2 — "Your Nostr Key Is Your Login" (`solid-nostr.html`)
**Topic**: did:nostr identity, NIP-98 Schnorr authentication, ACL
with did:nostr agents.
**solid-pod-rs mapping**:
| NIP-98 HTTP auth (kind 27235) | `auth::nip98::verify_at` | present |
| Schnorr signature verification | `auth::nip98::verify_schnorr_signature` (feature `nip98-schnorr`) | present |
| did:nostr DID Document publication | `solid-pod-rs-nostr` crate: `render_did_document_tier1`, `render_did_document_tier3` | present |
| did:nostr <-> WebID resolver | `solid-pod-rs-nostr` crate: `NostrWebIdResolver` | present |
See GAP-ANALYSIS.md section C.3 (Authentication).
---
### Part 3 — "HTTP 402: The Missing Status Code" (`solid-402.html`)
**Topic**: PaymentCondition in WAC ACLs, membership gates, deposit
verification via the 402 status code.
**solid-pod-rs mapping**:
| `PaymentCondition` in WAC | `wac::conditions::PaymentCondition` | present |
| HTTP 402 response body | `payments::payment_required_body()` | present |
| Payment discovery endpoint | `payments::pay_info()` | present |
See GAP-ANALYSIS.md section C.9 (Payments).
---
### Part 4 — "Pay Per Read" (`solid-pay.html`)
**Topic**: Per-read micropayments, balance deduction, X-Cost and
X-Balance response headers.
**solid-pod-rs mapping**:
| Balance deduction on read | `payments::debit()` | present |
| Balance credit on deposit | `payments::credit()` | present |
| X-Cost / X-Balance headers | `payments::payment_response_headers()` | present |
---
### Part 5 — "Your Pod Is Your Bank" (`solid-balance.html`)
**Topic**: Webledger JSON format, TXO URI scheme
(`txo:chain:txid:vout`), balance endpoints.
**solid-pod-rs mapping**:
| WebLedger JSON storage | `payments::WebLedger` struct | present |
| TXO URI parsing | `payments::parse_txo_uri()` | present |
| Balance endpoint `/pay/.balance` | `payments::balance_response()` | present |
---
### Part 6 — "Anchored to Bitcoin" (`solid-blocktrails.html`)
**Topic**: BIP-341 key chaining (SHA256 tweak, scalar addition,
P2TR address derivation), the `blocktrails` npm package.
**solid-pod-rs mapping**:
| BIP-341 chained public key derivation | `mrc20::bt_derive_chained_pubkey()` | present (feature `bip341-taproot`) |
| BIP-341 chained private key derivation | `mrc20::bt_derive_chained_privkey()` | present (feature `bip341-taproot`) |
| P2TR address derivation | `mrc20::bt_address()` | present (feature `bip341-taproot`) |
| Anchor verification against mempool | `mrc20::verify_mrc20_anchor()` | present (feature `bip341-taproot`) |
---
### Part 7 — "Your Pod, Your Token" (`solid-tokens.html`)
**Topic**: MRC20 token minting, `/pay/.buy` and `/pay/.withdraw`
endpoints, portable MRC20 proofs.
**solid-pod-rs mapping**:
| MRC20 state machine | `mrc20::Mrc20State`, `Mrc20Op` | present |
| State validation | `mrc20::validate_mrc20_state()` | present |
| Hash chain verification | `mrc20::verify_state_link()` | present |
| Deposit verification | `mrc20::verify_mrc20_deposit()` | present |
| JCS canonicalisation (RFC 8785) | `mrc20::jcs()` | present |
---
### Part 8 — "Multi-Currency" (`solid-multi.html`)
**Topic**: Multi-chain support (btc, tbtc3, tbtc4, signet),
`/pay/.offers`, `/pay/.sell`, `/pay/.swap`.
**solid-pod-rs mapping**:
| Multi-chain config with mempool URLs | `payments::ChainConfig` (btc, tbtc3, tbtc4, signet presets) | present |
| `/pay/.offers` listing | not implemented | **missing** (P2) |
| `/pay/.sell` order placement | not implemented | **missing** (P2) |
| `/pay/.swap` atomic swap | not implemented | **missing** (P2) |
The multi-chain deposit and verification infrastructure is at parity.
The peer-to-peer trading surface (sell, swap, offers) is not
implemented.
---
### Part 9 — "Your Pod Is an Exchange" (`solid-amm.html`)
**Topic**: Automated market maker, constant-product `x*y=k`,
`/pay/.pool`, liquidity provision.
**solid-pod-rs mapping**:
| AMM constant-product pool | not implemented | **missing** (P2) |
| `/pay/.pool` endpoint | listed in `payments::pay_info()` discovery but no backing logic | **missing** (P2) |
The pool endpoint appears in the discovery response but is
non-functional.
---
### Part 10 — "Beyond Tokens" (`solid-beyond.html`)
**Topic**: Programmable state anchoring — NFTs, smart contracts, git
commits via blocktrails.
**solid-pod-rs mapping**:
| Token-specific state trails | `mrc20::Mrc20Trail` | present |
| Generic state anchoring abstraction | not abstracted beyond MRC20 | **partial-parity** (P3) |
| NFT / smart contract rules engine | not implemented | **missing** (P3) |
`Mrc20Trail` covers the token-specific case. A generic state
anchoring layer that could anchor arbitrary data types (NFTs, smart
contracts, git commits) is not yet abstracted from the token-specific
implementation.
---
## Summary
| 1 | Your Data, Your Server | `provision`, `wac`, `storage::fs` | full |
| 2 | Your Nostr Key Is Your Login | `auth::nip98`, `solid-pod-rs-nostr` | full |
| 3 | HTTP 402: The Missing Status Code | `wac::conditions`, `payments` | full |
| 4 | Pay Per Read | `payments` | full |
| 5 | Your Pod Is Your Bank | `payments` | full |
| 6 | Anchored to Bitcoin | `mrc20` (feature `bip341-taproot`) | full |
| 7 | Your Pod, Your Token | `mrc20` | full |
| 8 | Multi-Currency | `payments::ChainConfig` | partial (trading surface missing) |
| 9 | Your Pod Is an Exchange | `payments` (discovery only) | missing (AMM not implemented) |
| 10 | Beyond Tokens | `mrc20::Mrc20Trail` | partial (token-specific only) |
**Overall**: 7 of 10 articles at full parity, 2 partial, 1 missing.
The core payment/token lifecycle (deposit, balance, debit, buy,
withdraw, blocktrail anchor) is fully implemented. The exchange
layer (sell, swap, offers, AMM pool) and generic state anchoring are
the remaining gaps.