v0.6.7-rc1 — the gas model (constraint set 8), chain 18 cut build

v0.6.7-rc1 — the gas model (constraint set 8), the chain-18 cut build

Release candidate for the chain-18 cut. Commit 0017de7 (feat/gas-chain18, rebased onto b388540 = v0.6.4 / chain 17). Circuits feat/cs8-gas 18c2627 vendored (constraint set 8). Built on E with RAND_BUILD_SHA=0017de7; rand_getVersion reports 0.6.7-rc.1.

What it is (spec docs/superpowers/specs/2026-09-28-gas-model-design.md):

• Phase 0: a header-priced call floor as node policy (--gas-price/--byte-price, defaults 100/800).
• Phase 1: the in-circuit gas meter (pv::GAS, pv::NUM 35), gas_max(t, klh, slh) = (2^t−1) + 2^(t−2) + 191·(2^klh/32) + 63·(2^slh/64), a declared GAS_LIMIT per proof; genesis gas section (bundle proofs pinned at 20 479, auth proofs at 1 279).
• Phase 2: dynamic prices (GasPrices, 12.5 % a step toward half-full blocks, floored at the genesis prices), rand-state-7, rand_getLimits/rand_estimateFee/rand_status.gas_prices, wallet --gas-limit.
• Chain 18 is cut with --envelope-bytes 1860 (the encrypted memo on).

Compatibility: every verifier key changes. This build refuses chains 14–17 at startup; a v0.6.3 node verifies no chain-18 proof. Roll = all-stop/all-start via deploy/cutover-fleet-chain18.sh. A cs7 wallet proves nothing chain 18 accepts.

v0.6.6 (d742a9b) stays as the pre-rebase tag. v0.6.7 follows with further fixes.

file	sha256
rand-node	500b2995ed0bd648225b078339103ba91cdd3c713c135faa558e9b96dca7a3fa
rand	e80e5692e31061f47cd60827514b163a3e388044e672b8f39a3dfff11ae6f79a
rand-prover	0b23afbe4e8543c5a7da2aadf21433e41bc252b8b4a1b63b1a174664f88bd02c