Function is_rust_diagnostics_cold

src/diagnostics/mod.rs:107–113

Whether the Rust diagnostics build is "cold" — i.e. the private cargo target dir does not exist yet or is effectively empty. The first `cargo check` against a cold tree builds every dependency from scratch and can block for minutes on a large workspace; the MCP layer uses this to offer a non-blocking prewarm instead of freezing the agent. Returns `false` for projects without a `Cargo.toml` (nothi

(project_root: &Path)

/// Returns `false` for projects without a `Cargo.toml` (nothing to warm) and
/// once the target dir has any build artifacts (subsequent checks are fast).
pub fn is_rust_diagnostics_cold(project_root: &Path) -> bool {
    if !project_root.join("Cargo.toml").exists() {
        return false;
    }
    let target_dir = rust::target_dir_for(project_root);
    dir_is_missing_or_empty(&target_dir)
}

/// True when `path` does not exist, is not a directory, or contains no
/// entries. Any read error is treated as "cold" so we err toward prewarming