Demotion is defined as loss of her seat at the Cabinet without acquiring immediately another Cabinet position. All Cabinet positions are treated equal. Merely attending Cabinet is not the equivalent of membership of Cabinet. Temporary leave for maternity or illness is ignored: if the market otherwise resolves whilst she is on leave the resolution will be N/A. This site will be treated as definitive: https://www.gov.uk/government/ministers
Vacancy includes resignation as Prime Minister to take effect at a future date or event (such as election of a new Conservative Party leader). The vacancy is deemed to be from the moment the resignation is announced, not when it later takes effect.
Market is resolved when Badenoch is demoted, there is a change or vacancy for the Prime Minister or Parliament is dissolved, whichever occurs first.