devo: Instructions file for Codex

AGENTS.md

Rust

This repository is a Rust-based coding agent, currently called devo.

• All crate names use the devo- prefix. For instance, the crate in the core directory is named devo-core.
• When using format!, inline variables directly inside {} whenever possible.
• Always collapse nested if statements according to https://rust-lang.github.io/rust-clippy/master/index.html#collapsible_if
• Inline format! arguments whenever possible, following https://rust-lang.github.io/rust-clippy/master/index.html#uninlined_format_args
• Prefer method references instead of closures where applicable, per https://rust-lang.github.io/rust-clippy/master/index.html#redundant_closure_for_method_calls
• Avoid using bool or unclear Option parameters that lead to ambiguous calls like foo(false) or bar(None). Instead, use enums, clearly named methods, newtypes, or other idiomatic Rust patterns that improve readability at the callsite.
• If such API changes are not feasible and positional literals must still be used, follow the argument_comment_lint rule:
  • Add an exact /*param_name*/ comment before unclear positional literals (e.g., None, booleans, numeric values).
  • Do not include these comments for string or character literals unless they genuinely improve clarity, as these are exempt.
  • The comment must exactly match the parameter name in the function signature.
• Make match expressions exhaustive whenever possible, avoiding wildcard arms.
• Any newly introduced traits must include documentation explaining their purpose and how implementations should behave.
• In tests, favor comparing full objects rather than asserting on individual fields.
• If an API is added or modified, update the relevant documentation in the docs/ directory when necessary.
• Avoid introducing small helper functions that are only used once.
• Keep modules reasonably sized:
  • Prefer creating new modules instead of expanding existing ones.
  • Aim to keep modules under 500 lines of code, excluding tests.
  • If a file grows beyond ~800 lines, place new functionality in a separate module unless there is a strong, documented justification not to.
• When running Rust-related commands (e.g., just fix or cargo test), allow them to complete without interruption, do not try to kill them using the PID. Slow execution due to Rust’s locking behavior is expected.
• Agent can not apply patch to a file more than 800 lines, cause windows patch length limit, agent would failed to apply patch.
• Do not introduce trivial wrapper functions — call the underlying function directly unless reuse or abstraction is clearly justified.
• Exclude the target folder when using glob or grep, since it contains a large number of Rust build artifacts.