fix(revm): restore original_value after token fee reimbursement

[panos-xyz]

Summary

• align the main-branch fix with the current runtime-tracker implementation instead of keeping a reimbursement-only patch
• add MorphTxRuntime to track forced-cold slot originals across token-fee deduction, EVM execution, and reimbursement
• cover both direct journal reimbursement and first-access SSTORE with regression tests

Context

main already had a partial fix based on MorphTxEnv::fee_slot_original_values, but that only covered the EVM SLOAD path. The reimbursement path still called transfer_erc20_with_slot directly and bypassed sload_morph, which let revm overwrite original_value for the fee-token balance slots.

This PR now matches the current in-progress implementation used on the working branch:

• move tx-scoped tracking out of MorphTxEnv and into a dedicated MorphTxRuntime
• wire that runtime through MorphContext
• restore tracked originals from a single source in all affected paths
• add a custom SSTORE override so forced-cold slots are also protected when the first main-execution touch is a write instead of a read

This replaces the earlier minimal reimbursement-only patch on this PR branch.

Test Plan

• cargo fmt
• cargo test -p morph-revm
• cargo test -p morph-evm

Summary by CodeRabbit

• New Features

  • Token-based fee reimbursement (ERC20 or EVM transfer paths) and cached per-transaction L1 data fee computation
  • L1 fee cap for circuit compatibility
  • Per-transaction runtime to track/restore forced-cold storage and new accessors for cached fees and pre/post-fee logs

• Bug Fixes

  • Restore original storage slot values and reset per-transaction caches/logs between iterations
  • Skip token reimbursement during fee-less simulations (e.g., eth_call)

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: a6b9e0d2-be17-4f40-82c8-6c4cde006def

📥 Commits

Reviewing files that changed from the base of the PR and between c61633f and b141eb6.

📒 Files selected for processing (3)

• crates/revm/src/handler.rs
• crates/revm/src/runtime.rs
• crates/txpool/src/validator.rs

---

📝 Walkthrough

Walkthrough

Adds per-transaction runtime state and L1-data fee caching; extends fee handling to support ERC20 token reimbursement (slot-based or internal EVM-call), introduces helpers to perform/restore fee transfers and preserve original storage values, and updates morph sload/sstore behavior and tests.

Changes

Cohort / File(s)	Summary
Handler / Token-fee flow crates/revm/src/handler.rs	Expanded fee handling to support token-based payments alongside ETH, added per-tx L1 data fee calculation/caching, token reimbursement via slot writes or internal EVM CALLs, early-exit for eth_call scenarios, and new helpers (evm_call, evm_call_balance_of, transfer_erc20_with_evm, transfer_erc20_with_slot, restore_tracked_original_values, calculate_caller_fee_with_l1_cost).
EVM surface & accessors crates/evm/src/evm.rs	Now constructs an inner MorphEvm, derives precompiles from it, wires chain config for MorphTxRuntime, and exposes new accessors: cached_token_fee_info, cached_l1_data_fee, take_pre_fee_logs, take_post_fee_logs plus inspector/context helpers.
revm core: runtime, morph instrs & journals crates/revm/src/evm.rs, crates/revm/src/runtime.rs, crates/revm/src/lib.rs	Introduced MorphTxRuntime (per-tx forced-cold slot originals) and added runtime module export; replaced prior fee-slot tracking with runtime-based tracking; added sload_morph/sstore_morph and restore_tracked_original_value; added cached_token_fee_info, cached_l1_data_fee, pre_fee_logs and post_fee_logs fields and accessors.
L1 fee handling crates/revm/src/l1block.rs	Made Curie L1 fee fields concrete U256, added L1_FEE_CAP and applied cap in calculate_tx_l1_cost, updated related calculations and tests.
Tx envelope / MorphTx parsing crates/revm/src/tx.rs	Removed fee_slot_original_values from MorphTxEnv; eliminated RLP-based extraction helper and now extract fields directly from MorphTxEnvelope; adjusted constructor/initialization accordingly.
Tests / scaffolding crates/revm/src/handler.rs (cfg(test))	Added tests and harness code covering forced-cold slot preservation, token-fee reimbursements, and EVM-based token transfers.
Small changes crates/txpool/src/validator.rs	Replaced clone-from-lock with copy/dereference for L1BlockInfo retrieval.

Sequence Diagram(s)

sequenceDiagram
    participant Caller as Caller/Tx
    participant Handler as revm::handler
    participant EVM as MorphEvm
    participant Runtime as MorphTxRuntime
    participant DB as Journal/State

    Caller->>Handler: Submit transaction (may include token fee)
    Handler->>EVM: validate_and_deduct_fee (compute L1 data fee)
    EVM->>Runtime: cache per-tx L1 data fee & TokenFeeInfo
    Handler->>Runtime: track_forced_cold_slot(address, slot, original)
    alt token reimbursement via slot
      Handler->>EVM: transfer_erc20_with_slot(from,to,token,amt)
      EVM->>DB: write slot changes (journal)
      Runtime->>DB: restore_tracked_original_value for forced-cold slots
    else token reimbursement via internal CALL
      Handler->>EVM: evm_call(balanceOf/transfer calldata)
      EVM-->>Handler: result + logs (pre/post fee logs separated)
      Runtime->>DB: restore_tracked_original_value if needed
    end
    Handler->>Caller: continue execution with restored originals and fee logs

Loading

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

Possibly related PRs

• fix(revm): restore original_value after revm-state 9.0.0 #39: Adds collection/caching of original storage values for fee slots — closely related to the runtime-based restoration and sload/sstore changes.
• Refactor: System Call and L1 Message Handling in REVM #18: Modifies token-fee and L1-data-fee paths and cold-marking — overlaps token-fee validation and L1 fee handling.
• feat: Refactor alt-fee mechanism and update EVM configuration #14: Adjusts ERC20 fee transfer paths and internal-call handling — relevant to the new evm-call and reimbursement choices.

Suggested reviewers

• anylots
• chengwenxi

Poem

🐰
I hopped through slots both cold and deep,
Saved originals while others sleep,
Token fees twirled beneath the moon,
I called and wrote, then fixed each rune,
Carrots, logs, and state — all neat. 🥕

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately captures the main objective: restoring original storage values after token fee reimbursement, which is central to this substantial refactor introducing MorphTxRuntime for tracking forced-cold slots.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

• 📝 Generate docstrings (stacked PR)
• 📝 Generate docstrings (commit on current branch)

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch codex/token-fee-reimburse-fix

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@crates/revm/src/handler.rs`:
- Around line 629-633: The conditionals with the let-chains involving
tx.fee_slot_original_values and state.get_mut(&address) are misformatted and
failing rustfmt; reformat these blocks to match rustfmt style (e.g., split the
chained let/if into rustfmt-friendly lines or use parentheses) and run cargo fmt
--all to ensure CI passes; locate the affected expressions around
tx.fee_slot_original_values.iter().find(|(saved_address, saved_slot, _)|
*saved_address == address && *saved_slot == slot_key) and the subsequent let
Some(account) = state.get_mut(&address) and apply the same reformatting to the
other similar block later (the one with the same pattern at the other
occurrence).

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 57274f97-8334-4285-9795-bbc350892473

📥 Commits

Reviewing files that changed from the base of the PR and between 7d7f090 and 5480095.

📒 Files selected for processing (1)

• crates/revm/src/handler.rs

[panos-xyz]

Code review

Found 2 issues:

1. post_fee_logs assigned unconditionally even when EVM-path refund fails

In reimburse_caller_token_fee, the else branch (no balance_slot) sets evm.post_fee_logs = refund_logs before the error is checked. If transfer_erc20_with_evm emits a Transfer log during the EVM call and then fails a post-transfer validation (return value check, balance delta check), those logs are drained into post_fee_logs and merged into the receipt by the block executor. Go-ethereum's refundGas() is silent on failure — no logs are emitted. This would produce receipt hash mismatches when a token reimbursement fails via the EVM-call path.

Fix: only assign evm.post_fee_logs = refund_logs when the result is Ok.

morph-reth/crates/revm/src/handler.rs

Lines 443 to 460 in e685baa

	let log_count_before = evm.ctx_mut().journal_mut().logs.len();
	let result = transfer_erc20_with_evm(
	evm,
	beneficiary,
	caller,
	token_fee_info.token_address,
	token_amount_required,
	None,
	);
	let refund_logs: Vec<_> = evm
	.ctx_mut()
	.journal_mut()
	.logs
	.drain(log_count_before..)
	.collect();
	evm.post_fee_logs = refund_logs;
	result
	};

2. track_forced_cold_slot_from_state is dead code

MorphTxRuntime::track_forced_cold_slot_from_state is defined but never called anywhere in the codebase. All call sites use track_forced_cold_slot directly after manually extracting slot.original_value. This method should be removed or used to replace the manual extraction pattern.

morph-reth/crates/revm/src/runtime.rs

Lines 36 to 50 in e685baa

	#[inline]
	pub fn track_forced_cold_slot_from_state(
	&mut self,
	state: &EvmState,
	address: Address,
	slot: U256,
	) -> Option<U256> {
	let original_value = state
	.get(&address)
	.and_then(|account| account.storage.get(&slot))
	.map(|slot_state| slot_state.original_value)?;
	self.track_forced_cold_slot(address, slot, original_value);
	Some(original_value)
	}

---

Generated with Claude Code

_{- If this code review was useful, please react with 👍. Otherwise, react with 👎.}