Usability of the asensei app in terms of user satisfaction will be measured through semi structured interviews to collect participant feedback regarding the applications usability, perceived usefulness, and satisfaction. Higher and lower subjective ratings collated during the interview could represent different aspects of the app's performance and user experience. For example, a higher rating within interviews among participants may typically represent greater satisfaction with the mobile app with an increase likelihood to find the app user friendly, useful, and enjoyable to use. On the other hand, lower subjective feedback may typically signify dissatisfaction with the app.

Preliminary data on physical activity will subjectively measure physical activity using the self-administered Godin Leisure Time Exercise Questionnaire which is a validated self-reported physical activity measurement used in cancer care. This will be assessed for change at three different time points: at baseline (T0), pre surgery (T1) and 30 days post-surgery (T2). The minimum and maximum values within the questionnaire used ranges from (0-119) where higher scores indicate higher level of leisure time exercise participation.

The 6-minute walk test (6MWT) will assess the distance walked over 6 minutes as a sub-maximal test of aerobic capacity. This outcome measure will be used to determine changes in physical function levels and cardiorespiratory fitness. This will be assessed for change at three different time points: at baseline (T0), pre surgery (T1) and 30 days post-surgery (T2). The minimum score is zero indicating that the participant was unable to walk any distance within the six minute time frame and the highest score is the distance walked by the participant in six minutes.

The timed up and go test (TUAG) will assess a person's mobility and balance using the time that a person takes to rise from a chair, walk three meters, turn around, walk back to the chair, and sit down. This will be assessed for change at three different time points: at baseline (T0), pre surgery (T1) and 30 days post-surgery (T2). The lower the time score represents the shortest time taken to complete the task, indicating better mobility and functional ability. The higher the time score represents the longest time taken to complete the task suggesting potential mobility issues or functional limitations.

The Five times sit to stand test (5XSST) will assess lower extremity strength and frailty in patients with cancer. It is a simple test that evaluates the time taken to complete five repetitions of standing up from a seated position and sitting back down again. This will be assessed for change at three different time points: at baseline (T0), pre surgery (T1) and 30 days post-surgery (T2). The lowest score is the shortest time taken to complete the task, indicating better lower body strength and mobility. The highest score is the longest time taken to complete the task, suggesting potential difficulties in lower body strength and functional mobility.

Anthropometry will be assessed as height, weight, and body composition. Body composition will be assessed and calculated using Body Mass Index in the standard manner as height and weight. These multiple measurements will be aggregated to arrive at one reported value (e.g., weight and height will be combined to report BMI in kg/m) This will be assessed for change at three different time points: at baseline (T0), pre surgery (T1) and 30 days post-surgery (T2).

The handgrip test will be assessed and measured using a hand dynamometer to assess for grip strength. Handgrip strength can be used in cancer patients to evaluate nutritional risk and the need for nutritional intervention. This will be assessed for change at three different time points: at baseline (T0), pre surgery (T1) and 30 days post-surgery (T2). It measures the maximum force a person can generate while squeezing a handgrip dynamometer. The score is typically measured in kilograms and indicates the strength of the participants hand muscles. The lowest score is the weakest grip strength measurement achieved by the participant and the highest score is the strongest grip strength measurement obtained during the test.

The Patient Generated Subjective Global Assessment questionnaire (PG-SGA) will be used as an assessment tool to identify those most at risk of malnutrition. This will be assessed for change at three different time points: at baseline (T0), pre surgery (T1) and 30 days post-surgery (T2). It does not have a specific numerical score range like some other tests. Instead it involves a series of questions and assessments that are used to evaluate a participants weight changes, dietary intake, symptoms and functional capacity. The results are typically categorised into different levels of malnutrition of nutritional risk, ranging from well nourished to severely malnourished.

The patient health questionnaire (PHQ-9) will be used as an assessment tool to identify those participants in need of further support out with the universal programme provided by the asensei app. This will be assessed for change at three different time points: at baseline (T0), pre surgery (T1) and 30 days post-surgery (T2). The PHQ-9 is a self assessment tool used to screen and assess the severity of depression. It consists of nine questions that measure the frequency of various depressive symptoms over the past two weeks. The PHQ-9 scores range from 0-27, with higher scores indicating greater severity of depressive symptoms and the lowest score is 0 indicating the absence of depressive symptoms.

The EORTC QLQ-OG25 (European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire- Oesophagogastric Module 25) is a validated screening tool used in the quality-of-life metric pilots for patients with oesophageal-gastric cancer to be assessed for change at three different time points: baseline (T0), pre surgery (T1) and 30 days post-surgery (T2). The scoring for the EORTC QLQ-OG25 questionnaire is not a simple numerical range. It involves transforming raw scores into a scale of 0 to 100, where higher scores represent better functioning or higher levels of symptomatology, depending on the question. For example, higher scores on functional scales indicate better function and well-being, while higher scores on symptom scales indicate more severe symptoms. The scores are then interpreted in relation to the patient's condition and the context of their cancer diagnosis and treatment.