Fault fees and the other reward-derived charges after Solstice

[lucaniz]

FIP-0118 splits the block reward: an elected leader receives floor(w1 * BR), with w1 ramping from 95% down to a floor of 50%. The reward actor's this_epoch_reward is deliberately left whole, and the miner actor still sizes several charges from it, with no w1 anywhere.

Those charges are projections of what a sector earns. The fault fee says so in the actor code: the projection period exists so that "a miner pays back at least the expected block reward earned since the last successful PoSt". It is BR(t, 3.51d) charged once per proving period, so a faulty day costs 3.51 days of income today and 7.02 at the floor of the ramp. The same holds for the invalid-WindowPoSt penalty, for the consensus-fault penalty with its reporter reward, and for the input to the cap FIP-0100 places on the daily fee.

It is not a large number. The fault fee came to about 214,000 FIL over the last 365 days, 0.93% of minted rewards, so scaling it returns at most about 107,000 FIL a year against roughly 11.5M FIL of reduced receipts. The argument is that the charge should mean what it says.

Proposal

Carry the consensus weight to the miner actor and apply it where such a charge is computed, leaving this_epoch_reward and the reward actor's issuance accounting untouched.

Two message types need the weight, not one: ThisEpochRewardReturn for the direct calls, and DeferredCronEventParams for the cron path, which is where the fault fee is actually charged.

Charges would be sized with max(w1, 0.5), the published floor of the FIP-0118 schedule. FIP-0118 L2425-2427: "Changing that split changes network economics, so every discretionary SWA write requires a published and accepted FIP." A weight below the published floor therefore arrives as a FIP, and that is where these charges would be revisited.

Initial pledge and the PreCommit Deposit are unchanged. The termination fee and the daily fee keep their formulas and constants, and neither moves at current values, though both read a quantity this proposal scales: the termination fee through its 1.05 * FF floor, the daily fee through its block-reward cap.