Function assert_pda_external 

pub fn assert_pda_external(
    account: &AccountView,
    seeds: &[&[u8]],
    program_id: &Address,
) -> Result<u8, ProgramError>

Verify a PDA derived from an external program’s seeds. Returns the bump.

Same as assert_pda but makes intent clear: the program_id belongs to another program (metadata, ATA, etc.), not yours.

let bump = assert_pda_external(
    metadata_account,
    &[b"metadata", metadata_program.as_ref(), mint.as_ref()],
    &programs::METADATA,
)?;