Front Side of Card Does Not Show Correct Custom Algorithm Intervals

[SpicyRicecaker]

This issue is from an AnkiWeb review. I added some pictures for clarity.

Incorrect Behavior 1 :

When using FSRS4Anki (a custom card scheduling algorithm for Anki) along with this add-on, the front of the card shows intervals from Anki's native algorithm (see Figure 1).

Figure 1: Reviewing a Card With FSRS4Anki and Flexible Grading Add-on

Expected Behavior 1:

When using FSRS4Anki along with this add-on, the front of the card should display intervals from FSRS4Anki's custom algorithm (see Figure 2)

Figure 2: Reviewing a Card With FSRS4Anki but Without Flexible Grading Add-on

Notes

Once the card is flipped, the backside displays the correct custom intervals (see Figure 3).

Figure 3: A Flipped Card With FSRS4Anki and Flexible Grading

Incorrect Behavior 2:

After rating the card, the Last grade (on the top toolbar) displays the custom interval for the previous (see Figure 4). In the particular case of Figure 4, there seems to be some sort of rounding error on the "Last Grade".

Figure 4: The "Last Grade" Interval of the Same Flipped Card from Figure 1 and Figure 2

Expected Behavior 2:

The Last Grade should display the same information as the backside of the card (as seen in Figure 3).

[tatsumoto-ren]

Since we don't recommend FSRS4Anki, and since I don't use it personally, I can't say why the intervals differ. Maybe the custom algorithm doesn't run until the back side is shown. One thing that might point towards this conclusion is that Flexible Grading gets estimated intervals by calling Reviewer._buttonTime() and doesn't calculate anything by itself.

The estimated interval and the final interval differ because Anki randomizes the new interval after a card is answered. The interval shown on the top toolbar (1.6mo) should be correct, but the estimated interval may deviate a bit. Please confirm if that is the case by checking the last review stats (alt+ctrl+i) and comparing the shown intervals.

There may be some difference between what the stats window reports and what the toolbar reports, but I'm assuming that's due to rounding.

[tatsumoto-ren]

Maybe if we use round() here, we can imitate the rounding anki does.