Function build_shield_from_identity_transition 

pub async fn build_shield_from_identity_transition<S: Signer<IdentityPublicKey>, P: OrchardProver>(
    identity: &Identity,
    recipient: &OrchardAddress,
    shield_amount: u64,
    nonce: IdentityNonce,
    signer: &S,
    signing_transfer_key_to_use: Option<&IdentityPublicKey>,
    user_fee_increase: UserFeeIncrease,
    prover: &P,
    memo: [u8; 36],
    sender_ovk: Option<OutgoingViewingKey>,
    platform_version: &PlatformVersion,
) -> Result<StateTransition, ProtocolError>

Build a ShieldFromIdentity transition: prove an outputs-only Orchard bundle paying shield_amount to recipient, then identity-sign it with a TRANSFER key.

The identity nonce must already be the next nonce for identity (the SDK fetches it); amount + fee is debited from the identity balance at execution.