Transaction priority

In Subtensor, transaction priority is determined by custom transaction extensions, which alter or override the default Substrate SDK behavior. Extensions affecting transaction priority are:

• ChargeTransactionPaymentWrapper (wraps ChargeTransactionPayment)
• DrandPriority

Substrate SDK combines priorities from all transaction extensions using addition.

ChargeTransactionPaymentWrapper

In the Substrate SDK, ChargeTransactionPayment normally calculates transaction priority based on:

• Tip — an extra fee paid by the sender.
• Weight — computational complexity of the transaction.
• Dispatch class — category of the transaction (Normal, Operational, Mandatory).

However, in Subtensor, ChargeTransactionPaymentWrapper overrides this logic. It replaces the dynamic calculation with a flat priority scale based only on the dispatch class.

Proxy fee payment

RealPaysFee lets a real account opt in to paying transaction fees for a delegate. The wrapper follows up to three consecutive proxy levels, requiring consent for each (real, delegate) pair. It stops at the first missing opt-in and keeps the nearest proven payer. If the outermost real has not opted in, the signer pays.

A batch, batch_all, or force_batch inside a supported proxy chain can supply the final level: every immediate item must be a proxy call for the same real account, opted in to paying for the enclosing real. For example, proxy(C, proxy(B, batch([proxy(A, call), ...]))) charges A only when C pays for the signer, B pays for C, and A pays for B. Batch lookup never descends into the items' inner calls.

Empty batches, mixed real accounts, non-proxy items, and proxy_announced do not extend fee propagation; the nearest proven payer remains responsible. Calls beyond the third proxy level are not inspected for fee payment. These limits affect fee selection only; normal proxy permissions still govern dispatch.

When a proxy real pays, the signer-chosen tip is dropped. Fee redirection preserves the original dispatch origin and the priority scale below.

Current priority values

Dispatch Class	Priority Value	Notes
Normal	1	Standard transactions
Mandatory	1	Rarely used, same as Normal
Operational	10_000_000_000	Reserved for critical system extrinsics (e.g.: sudo calls)

DrandPriority

Special pallet_drand priority: 10_000 for write_pulse extrinsic.