FILE009

Error

Rust code has formatting issues detected by rustfmt.

Why this matters

Consistent formatting reduces cognitive load during code reviews and prevents unnecessary diffs. rustfmt is the community standard for Rust code formatting.

How to fix

Run rustfmt to auto-fix formatting:

rustfmt path/to/file.rs

For the entire project:

cargo fmt

klaudiush auto-detects the Rust edition from Cargo.toml (defaults to 2021 if not found).

Configuration

[validators.file.rust]
enabled = true
use_rustfmt = true
timeout = "10s"
edition = ""               # auto-detected from Cargo.toml
context_lines = 2
rustfmt_config = ""        # path to rustfmt config

Disable the validator:

[validators.file.rust]
enabled = false

Hook output

When this error is triggered, klaudiush writes JSON to stdout:

permissionDecisionReason (shown to Claude): [FILE009] Rust code formatting issues detected. Run 'rustfmt <file>' to auto-fix formatting

systemMessage (shown to user): Formatted error with fix hint and reference URL.

additionalContext (behavioral guidance): Automated klaudiush validation check. Fix the reported errors and retry the same command.

Related

• FILE006 - gofumpt formatting
• rustfmt documentation