[Bug]: Accuracy can become negative after repeated corrections

[Siddhesh100711]

Hi @bilalmlkdev ! I'm Siddhesh, and I'm currently contributing to RhythmKey as part of my ROSPL open-source project.

While testing the typing engine locally, I came across this accuracy calculation issue and was able to reproduce it consistently.

What happened?

Accuracy can become negative when incorrect characters are repeatedly typed and then deleted with Backspace.

The Accuracy formula is documented as:

((Total Characters - Mistakes) / Total Characters) * 100

When a wrong character is typed, the mistake counter increases. Pressing Backspace removes the character from the current input, but the mistake count is not reduced. Repeating this process can therefore make the number of mistakes greater than the number of characters currently in the input.

For example, I was able to reproduce an Accuracy of approximately -780%.

This also appears to affect the accuracy values used in the performance graph/statistics.

Steps to reproduce

1. Go to /app/taketypingtest.
2. Start a typing test.
3. Type an incorrect character.
4. Press Backspace to remove it.
5. Repeat the incorrect character → Backspace sequence multiple times during the same test.
6. Finish the test.
7. Open the results screen and check the Accuracy value.
8. Observe that Accuracy can become negative.

What did you expect to happen?

Accuracy should remain within a valid percentage range (0-100) and should not become negative.

Incorrect attempts and corrected characters should also be handled consistently when calculating the final Accuracy.

Browser

Google Chrome 153

Theme

None

Screenshots or additional context

Additional context:

The issue was reproduced locally using the development build.

The documented Accuracy formula is:

((Total Characters - Mistakes) / Total Characters) * 100

The current implementation uses the current userInput.length as Total Characters. A wrong printable key increments mistakes, while Backspace removes the character from userInput without decrementing mistakes.

As a result, repeated corrections can cause mistakes to exceed the current number of characters, producing negative Accuracy values.

Examples observed during testing:

• Accuracy: -66%
• Accuracy: -4300%

No files were modified while investigating this issue.

[bilalmlkdev]

Hi Siddhesh, thanks for reporting this! The bug is caused by mistakes not being decremented when Backspace removes a wrong character. I've fixed it in useTypingHandlers.js - now when you backspace a mistyped character, the mistake count decreases accordingly. Accuracy should stay within 0–100% now. Please test it locally and feel free to verify the fix with the same reproduction steps. Great catch!

[bilalmlkdev]

Hi Siddhesh, issue #1 is already fixed on my end, the mistakes counter now decrements correctly when Backspace removes a wrong character, so accuracy can no longer go negative. That said, you've also identified a new set of layout bugs. I've opened issue #2 for those: [Bug]: Typing test layout overlaps content and clips footer. Please fork the repo and tackle that one next - fix the three layout issues (top bar overlap, keyboard selector near footer, dark theme footer clipping) and open a PR referencing #2. I'll review and merge once it's clean. Keep up the great work BUDDY!

…

On Sun, Sep 27, 2026 at 9:12 PM Siddhesh Gawade ***@***.***> wrote: *Siddhesh100711* created an issue (bilalmlkdev/rhythmkey#1) <#1> Hi @bilalmlkdev <https://github.com/bilalmlkdev> ! I'm Siddhesh, and I'm currently contributing to RhythmKey as part of my ROSPL open-source project. While testing the typing engine locally, I came across this accuracy calculation issue and was able to reproduce it consistently. What happened? Accuracy can become negative when incorrect characters are repeatedly typed and then deleted with Backspace. The Accuracy formula is documented as: ((Total Characters - Mistakes) / Total Characters) * 100 When a wrong character is typed, the mistake counter increases. Pressing Backspace removes the character from the current input, but the mistake count is not reduced. Repeating this process can therefore make the number of mistakes greater than the number of characters currently in the input. For example, I was able to reproduce an Accuracy of approximately -780%. This also appears to affect the accuracy values used in the performance graph/statistics. Steps to reproduce 1. Go to /app/taketypingtest. 2. Start a typing test. 3. Type an incorrect character. 4. Press Backspace to remove it. 5. Repeat the incorrect character → Backspace sequence multiple times during the same test. 6. Finish the test. 7. Open the results screen and check the Accuracy value. 8. Observe that Accuracy can become negative. What did you expect to happen? Accuracy should remain within a valid percentage range (0-100) and should not become negative. Incorrect attempts and corrected characters should also be handled consistently when calculating the final Accuracy. Browser Google Chrome 153 Theme None Screenshots or additional context Image: Image (view on web) <https://github.com/user-attachments/assets/bc9ed979-3c6c-488b-b56a-b3fc03bad0cd> Image: Image (view on web) <https://github.com/user-attachments/assets/54932e12-dc49-4db9-a48c-6c6b958f56d5> Additional context: The issue was reproduced locally using the development build. The documented Accuracy formula is: ((Total Characters - Mistakes) / Total Characters) * 100 The current implementation uses the current userInput.length as Total Characters. A wrong printable key increments mistakes, while Backspace removes the character from userInput without decrementing mistakes. As a result, repeated corrections can cause mistakes to exceed the current number of characters, producing negative Accuracy values. Examples observed during testing: - Accuracy: -66% - Accuracy: -4300% No files were modified while investigating this issue. — Reply to this email directly, view it on GitHub <#1?email_source=notifications&email_token=B4BKJNDLNOB3N6YCUPG3FBT5RE37HA5CNFSL4Z3JMQ5C6L3HNF2C22DVMIXUS43TOVSS6NJWGAZTGMBZGEZDTJTSMVQXG33OU5WWK3TUNFXW5JLFOZSW45FMMZXW65DFOJPWG3DJMNVQ>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/B4BKJNEBJIZQ6SER4UU6FFD5RE37HAVCNFSNUABGKJSXA33TNF2G64TZHMYTCNZSGU2TIOBVGE5US43TOVSTWNJWGAZTGMBZGEZDTILWAI> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/B4BKJNDBLST567AW52TGKGD5RE37HA5CNFSL4Z3JMQ5C6L3HNF2C22DVMIXUS43TOVSS6NJWGAZTGMBZGEZDTJTSMVQXG33OU5WWK3TUNFXW5JLFOZSW45FKMZXW65DFOJPWS33T> and Android <https://github.com/notifications/mobile/android/B4BKJNHXL3GZQ4WBNBGOW4T5RE37HA5CNFSL4Z3JMQ5C6L3HNF2C22DVMIXUS43TOVSS6NJWGAZTGMBZGEZDTJTSMVQXG33OU5WWK3TUNFXW5JLFOZSW45FOMZXW65DFOJPWC3TEOJXWSZA>. Download it today! You are receiving this because you were mentioned.Message ID: ***@***.***>