🗒️ Description

Implements SSTORE 0 to x to 0 refunds state gas directly to state_gas_reservoir instead of refund_counter, with frame scoped rollback on revert or exceptional halt (mirrors refund_counter semantics). Extends the journaling to the CREATE silent failure refunds introduced in #2704.

EIP text change: ethereum/EIPs#11532 (merged) + ethereum/EIPs#11548 (clarification).

Spec change: 1628020

When a storage slot is restored to its original zero value (0 to x to 0), the net state growth is zero. Refund 32 * cost_per_state_byte directly to the reservoir instead of through refund_counter. The regular gas write cost refund still goes through refund_counter. The refund happens immediately after the x to 0 change.

A new state_gas_refund counter on the Evm tracks inline reservoir refunds so they can be unwound with the frame:

• sstore increments state_gas_refund alongside the state_gas_left += ... / state_gas_used -= ... mutations.
• generic_create also increments state_gas_refund at all three silent-failure sites (insufficient balance / nonce / depth, address collision, child error) so feat(spec-specs, tests): EIP-8037 - CREATE failure refunds state gas to reservoir #2704's CREATE refunds follow the same rollback rule.
• incorporate_child_on_success propagates state_gas_refund to the parent (refund is recursively inheritable up the call stack on clean returns).
• incorporate_child_on_error subtracts state_gas_refund from the amount returned to the parent's reservoir and does not propagate it (refund is dropped with any reverting ancestor).

Net state growth is zero so block_state_gas_used excludes the refunded state gas.

Existing test update: fd49b8a

test_block_gas_refund_eip7778_no_block_reduction, expected block header gas_used now reflects the state gas refund reducing block_state_gas_used. Regular gas refund still excluded from block accounting per EIP-7778.

New tests: e001d16

Twelve tests in test_state_gas_sstore.py covering happy-path accounting, cross-frame propagation, and the rollback semantics on revert / exceptional halt:

• test_sstore_restoration_block_state_gas_zero, parametrized num_cycles=[1, 50]. Verifies block state gas is zero for 0 to x to 0 cycles.
• test_sstore_restoration_mixed_with_genuine_sstore, parametrized num_cycles=[1, 10]. Mixes restoration cycles with a genuine 0 to x, block state gas reflects only the genuine SSTORE.
• test_sstore_restoration_intermediate_values, 0 to x to y to 0 still triggers refund, independent of intermediate values.
• test_sstore_restoration_then_reset, 0 to 1 to 0 to 1 correctly charges once net (refund then re-charge).
• test_sstore_restoration_reservoir_replenished_inline, inline refund at x to 0 allows a subsequent 0 to x to succeed.
• test_sstore_restoration_reservoir_spillover, tx gas at the cap (reservoir zero), 0 to x state gas spills into gas_left, x to 0 refund goes to reservoir.
• test_sstore_restoration_cross_frame, parametrized over CALL / CALLCODE / DELEGATECALL via with_all_call_opcodes. Callee performs the full 0 to x to 0 cycle; slot lives in callee's storage for CALL and in caller's for CALLCODE / DELEGATECALL; the tx-level reservoir is refunded in every case.
• test_sstore_restoration_sub_frame_revert, same call-opcode parametrization. Sub-call does 0 to x to 0 then REVERT; a single-SSTORE probe sized to OOG by 1 detects any leaked refund.
• test_sstore_restoration_ancestor_revert, inner frame applies the refund and returns successfully, middle frame REVERTs; exercises the recursive propagation rule (success incorporate_child_on_success then ancestor incorporate_child_on_error).
• test_sstore_restoration_create_init_revert, parametrized over CREATE / CREATE2 via with_all_create_opcodes. CREATE init does 0 to x to 0 then REVERT, wrapped in an outer reverting frame so both the SSTORE refund and the feat(spec-specs, tests): EIP-8037 - CREATE failure refunds state gas to reservoir #2704 CREATE silent-failure refund must unwind together.
• test_sstore_restoration_create_init_success, parametrized over CREATE / CREATE2. Positive mirror: init writes and clears slot 0, returns empty runtime, CREATE succeeds.

🔗 Related Issues or PRs

• EIP text change: Update EIP-8037: more state gas accounting changes EIPs#11532 (merged)
• EIP text rollback clarification: Update EIP-8037: Clarify SSTORE restoration refund rollback semantics EIPs#11548

✅ Checklist

• All: Ran fast static checks to avoid unnecessary CI fails, see also Code Standards and Enabling Pre-commit Checks:

  just static

• All: PR title adheres to the repo standard - it will be used as the squash commit message and should start type(scope):.
• All: Considered updating the online docs in the ./docs/ directory.
• All: Set appropriate labels for the changes (only maintainers can apply labels).