The streak has nothing to do with calculating what level of the SRS ladder you’re on.

Let’s go through a hypothetical and keep a running streak log. We’ll call the “just finished the lesson and have 4 correct answers left to go” stage Apprentice 0.

- Right (1), SRS Apprentice 1
- Wrong (0), SRS Apprentice 0
- (same review session) Right (1) SRS Apprentice 0 (SRS didn’t go up because you got it wrong during this session, but your streak did go to 1 because you got 1 right in a row)
- Right (2) SRS Apprentice 1
- Right (3) SRS Apprentice 2
- Right (4) SRS Apprentice 3
- Right (5) SRS Guru

Basically, you can never end a session with a streak less than 1, but your SRS will still have gone down (or stayed down) if you got a wrong answer during the session.