🎨 Mosaic: UI Polish for CLI Errors

[madmax983]

• 🖌️ Before: CLI initialization errors and exits printed raw outcome_class: ... \n error: ... text to standard error without formatting, resembling a log file.
• ✨ After: Error outputs are formatted using crossterm colors with a bold red error: prefix, and the outcome_class debug information is dimmed so it recedes into the visual hierarchy.
• 🖼️ Visuals: Red colored error: tags and dimmed debug output for all CLI error exits.

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PR created automatically by Jules for task 9364451959914574599 started by @madmax983

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[gemini-code-assist]

Code Review

This pull request introduces terminal styling using the crossterm library for error and outcome class messages printed to stderr. The review feedback recommends checking if stderr is a terminal (using std::io::stderr().is_terminal()) before applying these styles to prevent polluting log files or breaking downstream parsers when output is redirected.

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[gemini-code-assist]

Unconditional ANSI escape codes are printed to stderr even when it is redirected to a file or a pipe (non-TTY). This can pollute log files and break downstream parsers. It is recommended to check if stderr is a terminal using std::io::stderr().is_terminal() before applying colors and styles.

            if std::io::stderr().is_terminal() {
                use crossterm::style::Stylize;
                eprintln!(
                    "{} {}",
                    "outcome_class:".dim(),
                    ExitCode::UsageError.outcome_class().dim()
                );
                eprintln!("{} {e}", "error:".red().bold());
            } else {
                eprintln!("outcome_class: {}", ExitCode::UsageError.outcome_class());
                eprintln!("error: {e}");
            }

[gemini-code-assist]

Unconditional ANSI escape codes are printed to stderr even when it is redirected to a file or a pipe (non-TTY). This can pollute log files and break downstream parsers. It is recommended to check if stderr is a terminal using std::io::stderr().is_terminal() before applying colors and styles.

    if std::io::stderr().is_terminal() {
        use crossterm::style::Stylize;
        eprintln!("{} {}", "outcome_class:".dim(), code.outcome_class().dim());
        eprintln!("{} {}", "error:".red().bold(), detail);
    } else {
        eprintln!("outcome_class: {}", code.outcome_class());
        eprintln!("error: {detail}");
    }

[chatgpt-codex-connector]

💡 Codex Review

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Reviewed commit: b7467bcff4

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[chatgpt-codex-connector]

Preserve the plain outcome label for scripts

When these exits run under CI or with stderr captured/piped, Stylize::dim() writes ANSI reset/style bytes around both tokens, so the documented outcome_class: <class> line is no longer present as plain text (for example, tests such as bench_calibrate check for outcome_class: calibration_optimistic, and simple parsers using that prefix will miss it). Please keep the stable label unstyled, or only add color on a TTY while preserving a parseable plain line.

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