Feat(tools): Add a tool to generate a custom genesis file based on a template and existing chain data

[dloghin]

Description

Adding a tool to bin/tools crate to allow the creation of a genesis file starting from a template genesis file and existing chain data. This is useful when we want to run a local devnet with XLayer testnet or mainnet data (e.g., from a snapshot). In such a case, the template genesis and existing chain data are the devnte genesis and testnet or mainnet snapshots, respectively.

The tool can be used as follows:

just install-tools
xlayer-reth-tools gen-genesis --datadir <path-to-existing-xlayer-reth-datadir> --chain xlayer-testnet --template-genesis ./config-op/genesis.json --output ./config-op/genesis-reth.json

We can also run this via Docker, by creating the xlayer-reth-tools image:

just build-docker-tools

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactoring (no functional changes)
• Other (please describe):

Code Guidelines

Before submitting your PR, please review the relevant code guidelines in the docs/ folder:

• Building on Reth Guide - Comprehensive guide for building on top of Reth

Specific Guidelines by Component:

• Chainspec & EVM Guide - For changes to chainspec or EVM configuration
• Database Guide - For changes to database tables or storage
• Engine & Consensus Guide - For changes to consensus or engine API
• Extension Guide - For adding extensions or plugins
• Node Builder Guide - For changes to node initialization
• Payload Builder Guide - For changes to block building logic

Checklist

• I have reviewed the relevant code guidelines in the docs/ folder
• My code follows the coding standards of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

Testing

Tested in xlayer-toolkit (branch dumi/gen-genesis).

[Vui-Chee]

Build Failure: just c fails

Running just c (the check command) fails immediately with:

error inheriting `reth-db-api` from workspace root manifest's `workspace.dependencies.reth-db-api`

Caused by:
  `dependency.reth-db-api` was not found in `workspace.dependencies`

Root Cause

bin/tools/Cargo.toml adds two new workspace dependencies that don't exist in the root Cargo.toml's [workspace.dependencies]:

1. reth-db-api — used in gen_genesis.rs for DbCursorRO, DbDupCursorRO, tables, and DbTx. This needs to be added to the workspace dependencies in the root Cargo.toml.

2. reth-node-types — added to bin/tools/Cargo.toml but never actually imported or used anywhere in the source code. This should either be removed from Cargo.toml, or if it was intended to be used, the workspace dependency needs to be added to root Cargo.toml and the relevant code should use it.

Fix

• Add reth-db-api to [workspace.dependencies] in the root Cargo.toml (with the appropriate git source matching other reth-* crates).
• Remove reth-node-types from bin/tools/Cargo.toml since it's unused, or add it to workspace deps if it's actually needed.

Code Review Notes (non-blocking, for after the build is fixed)

The implementation itself looks clean and well-structured. A few minor observations:

• read_account_bytecode redundant guard: The function takes Option<B256> and pattern-matches on None, but the caller at line 233 already checks account.bytecode_hash.is_some() before calling. Consider simplifying to take B256 directly.
• Empty code hash computed on every call: alloy_primitives::keccak256([]) in read_account_bytecode (line 306) is recomputed for every account with code. Consider making it a const or lazy_static / once_cell.
• The DockerfileTools exposes network ports (EXPOSE 30303 ...) which aren't relevant for a tools-only image — this is cosmetic but could be cleaned up.

[Vui-Chee]

All previous review comments have been addressed:

• reth-db-api / reth-node-types: Both added to workspace dependencies in root Cargo.toml — build resolves correctly now.
• EMPTY_CODE_HASH const: Moved from per-call keccak256([]) to a compile-time const at module level — good.
• Missing bytecode logging: Upgraded from debug! to warn! with a clearer message about potential DB corruption.
• Interrupt handler: Moved before DB initialization for earlier Ctrl+C handling.

just c passes (sweep-check, check-format, check-clippy, and tests all green). The one flaky test failure (block_fill_flashblocks) is pre-existing and not related to this PR — confirmed it passes on re-run on both main and this branch.

Minor non-blocking notes for future cleanup (not blocking merge):

• reth-node-types is in bin/tools/Cargo.toml but not imported in any source file — unused dependency.
• DockerfileTools still exposes network ports (EXPOSE 30303 ...) that aren't relevant for a tools-only image.

LGTM — good to merge.

[Vui-Chee]

Code Review

Reviewed the new gen-genesis subcommand. The overall structure is solid — clean separation of concerns, good use of template merging, and proper interrupt handling. Below are the issues found, ordered by severity.

[Vui-Chee]

All review comments have been addressed. LGTM — good to merge.