yoi/docs/report/2026-08-19-coder-toolchain-missing-rustfmt.md

Ticket validation image lacks rustfmt

While implementing T-613, cargo fmt --all failed before reading project sources because the active Rust toolchain does not provide the rustfmt component. The standalone rustfmt binary is also absent.

Observed commands:

$ cargo fmt --all
error: 'cargo-fmt' is not installed for the toolchain '1.90.0-x86_64-unknown-linux-gnu'.

$ rustfmt --version
bash: rustfmt: command not found

This prevents Workers from executing the repository-required formatting check or automatically normalizing Rust changes. The Coder can still run compile/tests and git diff --check, but formatting evidence remains weaker and review may surface avoidable formatting differences.

Suggested improvement: include the rustfmt component in the standard coding Workdir/toolchain image and verify cargo fmt --all -- --check during image qualification.