layoutd

Off-chain CLI for the Solana/Anchor ecosystem that diffs account struct layouts and classifies every field change as Safe, Review, or Danger before you ship a migration.

layoutd diff old.json new.json --account Vault
layoutd check old.json new.json --account Vault   # exits 1 on Danger → blocks CI
layoutd gen   old.json new.json --account Vault   # emits a Rust migration scaffold

Install

cargo install layoutd

Or install the latest from GitHub without publishing:

cargo install --git https://github.com/Rudraprajapati2612/layoutd-cli --bin layoutd

What it does

Anchor encodes accounts with Borsh (sequential field encoding). If you change a struct definition in a way that shifts byte offsets for existing data, every account already on-chain becomes unreadable. layoutd catches those mistakes in CI before they hit mainnet.

Safety classification

* Borsh is position-independent for deserialization; reorder only matters for on-chain size.

Usage

diff — inspect changes

layoutd diff old_idl.json new_idl.json --account EscrowVault

Accepts Anchor IDL JSON or a Rust source file (.rs):

layoutd diff vault_v1.rs vault_v2.rs --account Vault --zero-copy

check — CI gate

layoutd check old.json new.json --account Vault
# exits 0 → all changes safe
# exits 1 → at least one Danger (blocks CI)

Output a SARIF file for GitHub PR annotations:

layoutd check old.json new.json --account Vault --sarif results.sarif

gen — migration scaffold

layoutd gen old.json new.json --account Vault

Emits a Rust impl Migration block with a migrate() function, pre-filled for every detected change, plus a // Size: comment telling you whether you need realloc().

Flags

Acknowledgement file (--ack)

{
  "acknowledged": [
    { "account": "Vault", "field": "legacy_data", "change": "removed", "note": "intentional cleanup" }
  ]
}

Hints file (--hints)

Use when a field is renamed and moved to a different position simultaneously (auto-detection requires same position):

{
  "renames": [
    { "account": "Vault", "from": "amount", "to": "balance" }
  ]
}

GitHub Action

- name: Check Vault layout
  uses: Rudraprajapati2612/layoutd-cli@v0.1.0
  with:
    old-idl: old_idl.json
    new-idl: idl.json
    account: Vault
    sarif-output: layoutd.sarif
    zero-copy: 'false'       # optional
    ack-file: layoutd.ack    # optional
    hints-file: hints.json   # optional

Crates

License

Licensed under either of MIT or Apache-2.0 at your option.