Fee market

A demand-responsive base fee, a stated split of where each fee goes, and a supply bound that a future emission bug would hit rather than slip past. It is built, tested, and switched on nowhere: every network runs FeeConfig::DISABLED, whose activation height is u64::MAX, and nothing in crates/node/src/ calls the crate. crates/node/tests/fee_market_tests.rs checks both.

What the brief assumed, and what is true

Brief	This chain	What was built
base fee follows “block target gas saturation”	there is no block gas; fuel meters contract calls only, as a halting bound	the base fee follows serialized bytes, the resource a hybrid signature actually consumes
100% of the tip to “the PoUW miner/validator”	no coinbase, no validators; PoUW is a dark research branch	a one-per-block FeeClaim naming a beneficiary — the shape WorkClaim already has — so the header does not change
burned “from total supply”	a burn credits the unspendable fee sink: total is conserved and circulating falls	Supply::after_burn moves circulating only, and the tests assert exactly that
a hard maximum supply	nothing mints, so a cap is vacuous today	MAX_SUPPLY exists anyway, so the bound is in place before emission ever is

The rules

Base fee. EIP-1559’s control law over block bytes: at target it holds; at twice the target it rises by exactly one eighth; empty, it falls by one eighth. A rise is at least one unit, or a fee small enough to round every increase to zero would stay put under full blocks forever. It never falls below its floor.

Charge. A transaction pays base_fee × its serialized size + tip, where the tip is the smaller of what the sender offered and what max_fee leaves over. A max_fee that does not cover the base fee makes the block invalid — unlike a losing trade (invariant 7), this is knowable from the parent when the block is built, so including it is the producer’s error, not a surprise.

Split. 80% of the base fee is burned and 20% goes to the treasury; the whole tip goes to the claimant. The treasury share rounds down and the remainder burns, so no unit is ever created or lost and the only direction a rounding error moves value is out of circulation. A block with no claim burns its tips.

Supply. MAX_SUPPLY is 21,000,000 × 10⁸ base units. Nothing in this repository fixes a decimal convention or a genesis total — the committed genesis.json allocates nothing — so the number is a policy choice recorded in crates/fee-market/src/supply.rs, not a derivation. Once a value-bearing chain checks it, changing it is a hard fork.

Neural gain. A second, independently switched rule scales the base fee’s step by a gain from a compiled-in integer network. The gain is one-sided — it may only speed a rise or slow a fall — so the fee is never below what the linear rule would set, whatever features a producer writes. neural_activation_height is u64::MAX in both shipped configurations, so apply_block_fees charges exactly what it did before — see neural-gas.md.

The bounds no configuration may escape

crates/fee-market/src/limits.rs, compiled in and reachable by no transaction, the way crates/governance/src/limits.rs works: a change rate no faster than 1/8 and no slower than 1/1024 per block, a non-zero fee floor, a block-size target between 64 KiB (below which one signed transfer is over target on its own) and 16 MiB, and a treasury share of at most half. FeeConfig::validate checks every one, and apply_block_fees refuses an out-of-bounds configuration.

What activation requires

• Wire apply_block_fees into the state transition, with the fee claim beside claim_work — a consensus change with its own review.
• Move the governable parameters into governance::ParameterKey. They are not there now because that table is enumerated at genesis and adding keys changes every existing chain’s genesis state root. From then on they are read from state, never from these constants (invariant 17).
• Decide MAX_SUPPLY against a real genesis allocation.
• Wallets set max_fee and max_tip instead of the flat fee-sink output they use today.

Verifying

cargo test -p maya-fee-market              # the rules
cargo test --test fee_market_tests         # real transaction sizes, inertness
cargo kani -p maya-fee-market              # no unit created or lost; floor and step