Fix Rust Fmt

fix-rust-fmt

Fix Rust formatting issues in the optimism monorepo which would cause the rust-fmt CI job to fail.

When to Use

Use this skill when the rust-fmt CI job fails on a PR that touches Rust code.

Trigger Phrases

• "Fix rust formatting"
• "rust-fmt is failing"
• "Fix the rust-fmt CI job"

Prerequisites

• mise must be trusted and installed for this repo (mise trust && mise install)

Workflow

Step 1: Ensure mise tools are installed

From the repo root (or worktree root):

cd <REPO_ROOT> && mise install

This installs rust, just, and all other tools pinned in mise.toml.

Step 2: Run the formatter

cd <REPO_ROOT>/rust && mise exec -- just fmt-fix

Any files that change are the reason the CI job failed. Stage and commit them.

Notes

• mise exec -- activates the mise environment so cargo, just, and rustup resolve to the versions pinned in mise.toml.
• The nightly toolchain is required because the workspace uses unstable rustfmt options (see rust/rustfmt.toml).
• There is no need to inspect rust-fmt CI errors — if the job failed, running just fmt-fix and committing the result is the complete fix.