datepicker couldn't select Jan

[yuxuanzeng]

When select Jan as the month, the validation returns error. The component treats Jan as "00" month but it should be "01".

[kvishal2109]

Root cause
Both renderers use Date.getMonth() directly, which returns 0–11 (0 = January). HTML date inputs require 1–12, so January becomes "00" instead of "01".
Fix
Add 1 to the month before padding:
For Lit renderer (renderers/lit/src/0.8/ui/datetime-input.ts):
#formatInputValue(value: string) {
const inputType = this.#getInputType();
const date = value ? new Date(value) : null;
if (!date || isNaN(date.getTime())) {
return "";
}
const year = this.#padNumber(date.getFullYear());
const month = this.#padNumber(date.getMonth() + 1); // Add +1 here
const day = this.#padNumber(date.getDate());
const hours = this.#padNumber(date.getHours());
const minutes = this.#padNumber(date.getMinutes());
// ... rest of the method
}

For Angular renderer (renderers/angular/src/lib/catalog/datetime-input.ts):
protected inputValue = computed(() => {
const inputType = this.inputType();
const parsed = super.resolvePrimitive(this.value()) || '';
const date = parsed ? new Date(parsed) : null;

if (!date || isNaN(date.getTime())) {
return '';
}
const year = this.padNumber(date.getFullYear());
const month = this.padNumber(date.getMonth() + 1); // Add +1 here
const day = this.padNumber(date.getDate());
const hours = this.padNumber(date.getHours());
const minutes = this.padNumber(date.getMinutes());
// ... rest of the method
});