Introduce recent changes of FSRS4Anki, and want to collect some feedback

Continuing the discussion from New features of FSRS4Anki from v3.0.0 to v3.6.0:

During the past one month, FSRS4Anki only added three features. It is stable to me. So I want to collect some feedback for it. And here are the changes between v3.6.0 and v3.9.2:


  • Fix: set the good interval when the learning step only contains one step.


  • Feat: calculate the stability and difficulty for each review history and save it in prediction.tsv.
  • Fix: use the true repetition expectation from revlog to optimize suggested retention.
  • Feat: evaluate the model with cross-entropy loss and compare the model before/after training.


  • Feat: count retention expectation of all cards.


  • Fix: reschedule each card only once.

FSRS4Anki v3.9.2 has been released at:

By the way, I am waiting for the V3 scheduler at Ankimobile and Ankidroid to support the new custom scheduling feature, which allows FSRS4Anki to work on phones.


do you have any news that those apps will have the custom scheduler option. Or is it something you wish they had.

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They have already supported V3 Scheduler. It is reasonable to support the new feature of V3, right?

at least for ankidroid a feature request was already sent: [Feature request] Add support for the custom study feature recently implemented into Anki (2.1.55) · Issue #12620 · ankidroid/Anki-Android · GitHub

So they are at least aware that there’s some demand for it.


And it’s already in the current AnkiMobile beta.


@dae I have a question: If the scheduler save state variables in cards’ custom data field than sync them to a phone device and do some reviews there, will the custom data be lost? Or just keep it the same?

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yes but from the replies and the commit history. It dosen’t look like they are working on it

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@L.M.Sherlock I believe older v3 versions & v2 should leave any custom study data alone and not change it, but I have not tested to make sure.


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