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)
)

Loaded accounts (v0)

For a versioned (v0) transaction, compile(loaded_accounts:) takes the pubkeys resolved through address lookup tables. Those addresses leave the static account list entirely — accounts (and therefore Message#accounts) keeps only the static keys — while index_of still resolves them, against the combined space [static..., loaded...] the runtime rebuilds at execution time. Loaded accounts also drop out of the header. With no loaded accounts this is exactly the legacy compilation. The TransactionComposer supplies this for you when tables are registered.

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.