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date shift issue fix #855

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Merged
CodeWithCJ merged 1 commit into from
Mar 7, 2026
Merged

date shift issue fix #855

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22 changes: 21 additions & 1 deletion SparkyFitnessFrontend/src/contexts/PreferencesContext.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -345,7 +345,11 @@ export const PreferencesProvider: React.FC<{ children: React.ReactNode }> = ({

if (typeof date === 'string') {
// If it's a full ISO string with time (e.g. 2026-02-16T...), keep it as is for parseISO
if (date.match(/^\d{4}-\d{2}-\d{2}$/) || date.includes('T00:00:00')) {
if (
date.match(/^\d{4}-\d{2}-\d{2}$/) ||
date.includes('T00:00:00') ||
(date.endsWith('Z') && date.includes('T00:00'))
) {
Comment on lines +348 to +352
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@gemini-code-assist gemini-code-assist Bot Mar 7, 2026

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high

The condition date.includes('T00:00') is too broad and can lead to bugs. For example, a date string like '2023-01-01T00:00:30Z' would match, causing the time information to be incorrectly truncated. This can lead to subtle date-shifting issues.

The logic can be simplified and made more robust by checking if the time part of the string contains any non-zero digits. This correctly identifies true midnight timestamps while ignoring others.

        if (
          date.match(/^\d{4}-\d{2}-\d{2}$/) ||
          (date.includes('T') && !/[1-9]/.test(date.substring(date.indexOf('T') + 1)))
        ) {

// IMPORTANT: Treat YYYY-MM-DD as a literal local date to avoid UTC-to-Local shifting.
const datePart = date.split('T')[0];
if (datePart) {
Expand Down Expand Up @@ -389,6 +393,22 @@ export const PreferencesProvider: React.FC<{ children: React.ReactNode }> = ({
loggingLevel,
`PreferencesProvider: Parsing date string "${dateString}".`
);

// Handle literal date strings (YYYY-MM-DD or DB DATE format) to prevent shifting
if (
dateString.match(/^\d{4}-\d{2}-\d{2}$/) ||
dateString.includes('T00:00:00') ||
(dateString.endsWith('Z') && dateString.includes('T00:00'))
) {
const datePart = dateString.split('T')[0];
if (datePart) {
const [year, month, day] = datePart.split('-').map(Number);
if (year && month && day) {
return new Date(year, month - 1, day);
}
}
}
Comment on lines +397 to +410
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@gemini-code-assist gemini-code-assist Bot Mar 7, 2026

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medium

This block of logic for handling literal date strings is nearly identical to the logic in the formatDateInUserTimezone function. This duplication can make the code harder to maintain and can lead to inconsistencies if one instance is updated but the other is not.

I've left a comment on the other instance with a suggestion for a more robust implementation. It would be best to extract that improved logic into a shared helper function and call it from both formatDateInUserTimezone and parseDateInUserTimezone to avoid duplication.


const parsedDate = parseISO(dateString);
return startOfDay(parsedDate);
},
Expand Down