suggest username when taken on register

[caoerz-helen]

Resolves #1

Summary

When a user enters a username that is already taken on the register page, the UI now suggests an alternative username (e.g., test1 → test11) instead of only showing “Username taken”.

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Changes

• Added two helper functions in public/src/client/register.js:

  • async function isUsernameAvailable(name)
    • Slugifies the name.
    • Uses Promise.allSettled with api.head('/users/bySlug/:slug') and api.head('/groups/:name') to check whether a username or group already exists.
  • async function suggestedUsername(baseSlug)
    • Tries baseSlug + 1..20 and returns the first candidate where isUsernameAvailable returns true.

• Updated validateUsername(username, callback) to:

  • Keep all existing length and format checks (too short, too long, invalid characters).
  • After those pass, call isUsernameAvailable.
    • If available: call showSuccess as before.
    • If not available:
      • Call suggestedUsername(userslug).
      • If a suggestion is found, show a combined error message:
        • Existing [[error:username-taken]]
        • Plus [[user:username-taken-workaround, <suggestion>]]
      • Mark the input as invalid and set validationError = true.
      • If no suggestion is found, fall back to the original [[error:username-taken]] message.
  • Ensure callback() is still called once validation finishes.

• Kept the new text English-only by explicitly using config.defaultLang for the workaround message, as required.

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How I Tested

Case 1 – Username already taken

• Created a user test1 first.
• On the register page, typed test1 into the Username field and blurred the input.
• Observed:
  • Red error styling.
  • Two lines of text:
    • “Username taken”
    • “The username you requested was already taken, so we have altered it slightly. You are now known as test11.” (with a suggested alternative).

Case 2 – Username available

• Entered a unique username (e.g., unique123).
• Observed:
  • Green success styling.

Case 3 – Existing validation behavior

• Tried usernames that are:
  • Too short
  • Too long
  • Invalid per utils.isUserNameValid

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Screenshots

Register page showing taken username test1 and suggestion message

[coveralls]

Pull Request Test Coverage Report for Build 21601855893

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 78.841%

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Totals
Change from base Build 21503398961:	0.0%
Covered Lines:	25358
Relevant Lines:	30328

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💛 - Coveralls