Fix/Relearning cards' Intervals don't update after changing Desired Retention

[L-M-Sherlock]

fix #3234

[user1823]

Though I am not 100% sure, I think that your fix forces the recalculation of the interval every time a relearning card leaves the RELEARN state. If it is so, I think that the following fix is more efficient.

My idea is that Anki should clear the stored value of the interval of relearning cards (like d9f5487) when certain operations (listed below) are performed and then recalculate the interval during review if it is missing (because it was cleared).

The stored value of interval of relearning cards should be cleared when:

• the desired retention is changed
• the card is moved into different deck

I am not sure if we need to treat LEARN cards in the same way.

[L-M-Sherlock]

My idea is that Anki should clear the stored value of the interval of relearning cards

This implementation would be complex.

Though I am not 100% sure, I think that your fix forces the recalculation of the interval every time a relearning card leaves the RELEARN state.

It's necessary if we update to FSRS-5 because it considers the short-term schedule.

[user1823]

Does this work if there are no memory states at that point of time (e.g. the deck was changed, which clears the memory states)?

[dae]

The state is recalculated prior to that point.

[user1823]

@L-M-Sherlock

Not 100% sure if this is a bug, but still worth looking into:

A relearning card on AnkiDroid (24.06.2 backend) shows the intervals 20m 30m 6d 7d

The same card on Anki 24.06.3 rc1 shows the intervals 20m 30m 7d 7d

The change of Good interval from 6d to 7d may be caused by something like open-spaced-repetition/fsrs4anki-helper#343 (different fuzz is applied because the reps count has increased by 1 due to the last Again rating)

But, should the Easy button have the same interval as the Good button?

Card Info:

Card: A.apkg.zip (rename to remove .zip)

[L-M-Sherlock]

Seems I should set the interval as states.easy.interval plus one?

anki/rslib/src/scheduler/states/relearning.rs

Lines 135 to 149 in 0d8d816

	fn answer_easy(self, ctx: &StateContext) -> ReviewState {
	let scheduled_days = if let Some(states) = &ctx.fsrs_next_states {
	let (minimum, maximum) = ctx.min_and_max_review_intervals(1);
	let interval = states.easy.interval;
	ctx.with_review_fuzz(interval as f32, minimum, maximum)
	} else {
	self.review.scheduled_days + 1
	};
	ReviewState {
	scheduled_days,
	elapsed_days: 0,
	memory_state: ctx.fsrs_next_states.as_ref().map(|s| s.easy.memory.into()),
	..self.review
	}
	}

FSRS gives the same interval for good and easy in current case because FSRS doesn't consider the same-day reviews except the first one.

[user1823]

Seems I should set the interval as states.easy.interval plus one?

Maybe, yes