Module check 

Multi-tier validation system.

Hopper supports five validation levels:

1. Account-local: owner, signer, writable, size, discriminator, layout_id
2. Cross-account: vault.mint == mint.address(), authority matches
3. State-transition: status enum transitions, balance bounds
4. CPI composition: post-CPI invariants, no-CPI guards
5. Post-mutation: balance conservation, solvency invariants (via PostMutationValidator)

Validation can be composed with named groups (ValidationGroup), instruction-specific rule packs (TransitionRulePack), and multi-group bundles (ValidationBundle).

Modules

fast

Batched u32 header validation using a single-compare optimization.

graph

Composable Validation Pipeline.

guards

Security guard packs – safe-by-default exploit prevention.

modifier

Modifier-style composable account wrappers.

trust

Foreign-account trust profiles.

Functions

check_account

Combined account check: owner + discriminator + minimum size.

check_accounts_unique

Check that two accounts are unique (different addresses).

check_accounts_unique_3

Check that three accounts are all unique.

check_address

Check an account’s address matches an expected value.

check_discriminator

Check that the discriminator byte matches.

check_executable

Check that an account is executable (a program).

check_has_one

Check has_one: a stored address in account data matches another account’s address.

check_instruction_data_min

Check instruction data meets minimum length.

check_keys_eq

Check that two account addresses are equal.

check_lamports_gte

Check that the account has at least min lamports.

check_no_subsequent_invocation

Ensure our program is not invoked after the current instruction.

check_not_closed

Check that an account has not been closed (no close sentinel).

check_owner

Check that an account is owned by the expected program.

check_owner_multi

Check that an account is owned by one of the given program IDs.

check_program

Check that an account is a specific program: its key matches expected_program_id and it is flagged executable.

check_rent_exempt

Check that an account is rent exempt.

check_signer

Check that an account is a signer.

check_size

Check minimum data size.

check_system_program

System program check.

check_uninitialized

Check uninitialized: account data is empty.

check_writable

Check that an account is writable.

current_instruction_index

Read the current instruction index from the Instructions sysvar.

detect_flash_loan_bracket

Detect flash-loan bracket: same program called before AND after current.

find_and_verify_pda

Find a PDA and verify it matches the account, returning the bump.

instruction_count

Read the number of instructions in the current transaction.

is_zero_address

Check if a 32-byte address is all zeros (the default/system address).

keys_eq_fast

Fast 32-byte key equality check using 4x u64 comparisons.

read_program_id_at

Read the program_id of instruction at the given index.

rent_exempt_min

Rent-exempt minimum lamports for a given data size.

require_top_level

Require that the current instruction is top-level (not a CPI).

verify_pda

Verify a PDA with bump, using the cheap create_program_address path.

verify_pda_cached

Verify a PDA by reading the bump from account data at a known offset.