Function build_shielded_withdrawal_transition 

pub fn build_shielded_withdrawal_transition<P: OrchardProver>(
    spends: Vec<SpendableNote>,
    withdrawal_amount: u64,
    output_script: CoreScript,
    core_fee_per_byte: u32,
    pooling: Pooling,
    change_address: &OrchardAddress,
    fvk: &FullViewingKey,
    ask: &SpendAuthorizingKey,
    anchor: Anchor,
    prover: &P,
    memo: [u8; 36],
    fee: Option<Credits>,
    platform_version: &PlatformVersion,
) -> Result<StateTransition, ProtocolError>

Builds a ShieldedWithdrawal state transition (shielded pool -> core L1 address).

Spends existing notes and withdraws value to a core chain script output. The shielded fee is deducted from the spent notes. Any remaining value is returned to the shielded change_address.

Parameters

• spends - Notes to spend with their Merkle paths
• withdrawal_amount - Amount to withdraw to the core chain
• output_script - Core chain script to receive the funds
• core_fee_per_byte - Core chain fee rate
• pooling - Withdrawal pooling strategy
• change_address - Orchard address for change output
• fvk - Full viewing key for spend authorization
• ask - Spend authorizing key for RedPallas signatures
• anchor - Sinsemilla root of the note commitment tree (Orchard Anchor)
• prover - Orchard prover (holds the Halo 2 proving key)
• memo - 36-byte structured memo for the change output (4-byte type tag + 32-byte payload)
• fee - Optional fee override; if None, the minimum fee is computed automatically. If Some, must be >= the minimum fee.
• platform_version - Protocol version