Function target_dir_for

src/diagnostics/rust.rs:120–125

Private cargo target dir for diagnostics. Created lazily by cargo on first run and kept outside the project tree so diagnostics never create project-local `.tracedecay` folders. `pub(crate)` so the MCP handler can probe whether it is cold (never built) and decide whether to prewarm rather than block for minutes.

(project_root: &Path)

/// `pub(crate)` so the MCP handler can probe whether it is cold (never built)
/// and decide whether to prewarm rather than block for minutes.
pub(crate) fn target_dir_for(project_root: &Path) -> PathBuf {
    std::env::temp_dir()
        .join("tracedecay-target")
        .join(crate::storage::default_profile_project_id(project_root))
        .join("diagnostics")
}

/// Cargo emits messages of many levels — "warning" and "error" produce
/// diagnostics; "note", "help", "failure-note" are advisory and would