Function key_event_to_canonical_chord_string 

pub fn key_event_to_canonical_chord_string(
    code: KeyCode,
    mods: KeyModifiers,
) -> Option<String>

What: Serialize a raw key event into the canonical chord string used by the keybind parser, for the popup’s capture mode.

Inputs:

• code: Crossterm key code from the captured event.
• mods: Modifier flags from the captured event.

Output:

• Some(chord) such as "Ctrl+r" or "Shift+Tab" when the key is representable in keybinds.conf; None for unsupported codes (media keys, bare modifier presses, etc.), which capture mode should ignore rather than record.