refactor: apply simplify-review cleanups across core, common, and the binaries

[flyq]

Summary

Two /simplify review passes (4 review agents each: reuse, simplification, efficiency, altitude) over stateless-core and bin/stateless-validator, with the surviving findings applied — net −73 lines. No functional change on canonical-block paths; behavior-adjacent changes are called out below.

stateless-core

• Deleted the no-op hardfork reorder loop in ChainSpec::from_genesis: MegaethGenesisHardforks::into_vec() already yields canonical activation order (its literal is now documented as the single source of that order), and the "unknown fork" append branch was unreachable; the unused mega_mainnet_hardforks() template is gone with it.
• Removed the never-used EIP-3155 trace_writer parameter threaded through replay_block / verify_and_replay / validate_block / validate_block_deriving_updates (no caller here or in mega-reth ever passed Some), which also deletes the run_plain closure + cfg dance. mega-reth impact: its call sites drop a trailing None at the next version bump.
• WitnessExternalEnv::new / from_light_witness now share one from_metadata_kvs body; dead LightWitnessExecutor::kvs() accessor and a doubled doc block on create_evm_env removed.
• Reuse: the blob base-fee fraction comes from revm's BLOB_BASE_FEE_UPDATE_FRACTION_CANCUN instead of a hand-copied consensus constant; gas_used reads BlockExecutionResult::gas_used instead of recomputing from the last receipt.
• Hot path: WitnessDatabase reads use salt's find() + in-place decode and stack-allocated key encodings (pub(crate) helpers encode() also delegates to) — two heap allocations per witnessed state read and one per bucket_id_for_* call removed; dropped a per-miss SaltValue clone in LightWitness::metadata.
• Pipeline: chain_advancer runs pre_advance + advance_chain under spawn_blocking so redb commits (and the trace server's multi-MB block-data writes) no longer pin an async runtime worker; panics still propagate unchanged via resume_unwind. Also removed the in_flight_blocks mirror set, the metas lockstep vector, and the dead _reason parameter.
• ChainStore no longer carries the ContractStore supertrait (nothing consumed contracts through it); the forced stubs on the pipeline mock and the trace server's StubBlockStore are deleted.

stateless-validator + shared crates

• R2 mode no longer hands the data endpoints to RpcClient as placeholder witness endpoints: the constructor accepts an empty witness list, and a witness call with zero providers panics with a structural message instead of silently retrying mega_getBlockWitness against data endpoints. The trace server is unaffected (clap already enforces a witness source at startup).
• BackoffPolicy::schedule() / BackoffSchedule in stateless-common now own the jittered-doubling arithmetic previously duplicated between the RPC round-robin loop and the R2 GET loop; both consume it (fastrand dep dropped from the bin).
• install_prometheus_exporter hoisted into stateless_common::metrics; both binaries call it and the metrics-exporter-prometheus dep moved from the bins into common.
• BlockMeta::from_header added in core, replacing the three defaulting header→meta projections (validator + two in debug-trace-server); the strict anchor-init site in app.rs keeps its explicit missing-withdrawals-root error by design.
• verify_block_integrity now runs on the blocking pool and encodes each tx exactly once (keccak of that encoding checks the hash, the same bytes feed the transactions-root trie) — previously 2 clones + 2 encodes per tx inline on runtime threads.
• Validator cleanups: on_remote_height fn-pointer injection removed; run_with_signals takes report_validation: bool instead of an Option<String> it only ever .is_some()'d; phantom eth_getTransactionByHash metric series dropped; test-only set_anchor_block deleted (the roundtrip test now exercises reset_to_anchor); workers.rs renamed to runner.rs (docs updated); integration mock handlers deduped onto shared lookup helpers (also fixing a drifted bare unwrap on malformed params); make_block_meta test fixture unified.

Testing

cargo fmt / clippy --workspace --all-targets --all-features (0 warnings) / cargo sort clean; full workspace suite 328 passed / 0 failed; no-std check and no-std test compile (--no-default-features) pass.

Notes

• The empty-witness-list change relaxes a public RpcClient constructor check (startup rejection → loud panic at first misuse); the constructor test pins the new contract.
• Known follow-up (next PR): hoist the block-execution env assembly shared by replay_block and the trace server's TracingEnv::new, resolving their BlockLimits drift.

🤖 Generated with Claude Code

[mega-maxwell]

Claude review status

Living comment — rewritten in place. The review workflow keeps this single comment up to date instead of posting a new one each round, so it always describes the latest reviewed commit and the earlier text is intentionally gone. No reply is needed here; reply to a finding in its own review thread, and answer an open question in a reply on this PR. The next review round reconciles your answer.

🛠️ Review did not finish

Attempted head 9549ffff · updated 2026-08-02T07:46:23+00:00

This round did not publish: MODEL_ACTION_FAILED in phase review_retry. Anything listed below is from the last round that did. Re-run the workflow or push a new commit to try again.

[codecov]

Codecov Report

❌ Patch coverage is 81.13208% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.9%. Comparing base (682ec1a) to head (9549fff).

Files with missing lines	Patch %	Lines
crates/stateless-core/src/db.rs	0.0%	8 Missing ⚠️
crates/stateless-core/src/evm_database.rs	94.7%	1 Missing ⚠️
crates/stateless-core/src/light_witness.rs	0.0%	1 Missing ⚠️

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[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Keep block verification out of the RPC attempt timeout

When skip_block_verification=false and a large full block takes longer than per_attempt_timeout to verify, this spawn_blocking join is now inside round_robin_with_backoff's per-provider timeout; the retry loop can classify a healthy provider as stalled, retry the same block, and leave the blocking verification task running in the background. This affects the validator's default get_block(..., full_txs=true) path even without an overall deadline, because per-attempt timeouts are always applied. Consider fetching inside the timed RPC attempt but running the blocking integrity check after a successful fetch, or otherwise excluding the join from the provider-stall timeout.

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