Account Context

Solace::Utils::AccountContext is the bookkeeper that turns a set of accounts — each with its signer/writable flags — into the ordered account list and header a Message needs. It is the piece that frees you from ordering accounts by hand.

Solana requires accounts in a specific order (writable signers, readonly signers, writable non-signers, readonly non-signers), and the header counts must match. AccountContext collects accounts, deduplicates them, applies the ordering, and computes the header.

Registering accounts

Each method records an account with a role and returns self, so calls chain. Addresses accept anything #to_s (string, PublicKey, or Keypair).

Method	Role
set_fee_payer(pubkey)	The fee payer — writable signer, forced to index 0.
add_writable_signer(pubkey)	Writable, signs.
add_readonly_signer(pubkey)	Readonly, signs.
add_writable_nonsigner(pubkey)	Writable, doesn't sign.
add_readonly_nonsigner(pubkey)	Readonly, doesn't sign (e.g. a program ID).

If the same address is added more than once, its role is merged toward the most privileged combination (writable wins over readonly, signer over non-signer).

context = Solace::Utils::AccountContext.new
context.set_fee_payer(payer)
       .add_writable_nonsigner(recipient)
       .add_readonly_nonsigner(Solace::Constants::SYSTEM_PROGRAM_ID)
       .compile

Compiling

compile finalizes the ordering and computes the header. Afterward:

Accessor / query	Returns	Description
accounts	Array<String>	Ordered pubkeys — assign to Message#accounts.
header	Array<Integer>	The [required_sigs, readonly_signed, readonly_unsigned] header.
index_of(pubkey)	Integer	Position of an address (or -1 if absent) — feed these to instruction builders.
indices	Hash{String=>Integer}	Every address mapped to its index.
signer?, writable?, fee_payer?, …	Boolean	Role queries for an address.

ix = Solace::Instructions::SystemProgram::TransferInstruction.build(
  lamports:      1_000_000,
  from_index:    context.index_of(payer),
  to_index:      context.index_of(recipient),
  program_index: context.index_of(Solace::Constants::SYSTEM_PROGRAM_ID)
)

You usually don't touch it directly

The TransactionComposer owns an AccountContext internally: each composer registers its accounts into it, then the composer compiles it and resolves every builder's indices. You reach for AccountContext directly only when assembling a transaction without the composer layer.

merge_from(other_context) combines two contexts — the mechanism behind merging composers.