ui-common: Ignore mention suggestions that start with whitespace

[gpunto]

Goal

In the message composer, typing @ followed by spaces keeps the mention suggestion active with a whitespace-only query, which makes the group/role lookup return everything.

TypingSuggester.typingSuggestion lets a suggestion token start with whitespace, so @ produces a " " query that is forwarded to the lookup. The fix rejects suggestions that start with whitespace, while still allowing internal spaces so multi-word names (e.g. @John Doe) remain searchable.

Closes AND-1268

Implementation

• TypingSuggester now returns no suggestion when the token starts with whitespace. Internal and trailing spaces are still part of the token, so multi-word names keep working.

Testing

• New TypingSuggesterTest: empty token, single-word and mid-text tokens, multi-word and trailing-space tokens, and the leading-whitespace cases that now produce no suggestion.

Summary by CodeRabbit

• Bug Fixes
  • Improved mention suggestions so matches are no longer shown when the suggested text starts with whitespace, while still allowing valid internal spacing.
• Tests
  • Added coverage for mention suggestion behavior across common typing cases and invalid whitespace patterns.

[github-actions]

PR checklist ✅

All required conditions are satisfied:

• Title length is OK (or ignored by label).
• At least one pr: label exists.
• Sections ### Goal, ### Implementation, and ### Testing are filled, or the PR is bot-authored.
• An issue is linked (Linear ticket or GitHub issue), or the PR is bot-authored.

🎉 Great job! This PR is ready for review.

[github-actions]

SDK Size Comparison 📏

SDK	Before	After	Difference	Status
stream-chat-android-client	5.90 MB	5.90 MB	0.00 MB	🟢
stream-chat-android-ui-components	11.15 MB	11.15 MB	0.00 MB	🟢
stream-chat-android-compose	12.63 MB	12.63 MB	0.00 MB	🟢

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 8779fbb6-a1be-4b2a-9ff2-a6c2edd7e508

📥 Commits

Reviewing files that changed from the base of the PR and between 636018c and d7bf8c9.

📒 Files selected for processing (2)

• stream-chat-android-ui-common/src/main/kotlin/io/getstream/chat/android/ui/common/feature/messages/composer/typing/TypingSuggester.kt
• stream-chat-android-ui-common/src/test/kotlin/io/getstream/chat/android/ui/common/feature/messages/composer/typing/TypingSuggesterTest.kt

---

Walkthrough

typingSuggestion now rejects suggestion text that starts with whitespace, and a new parameterized test suite covers valid mention tokens and invalid whitespace and formatting cases.

Changes

Typing suggester whitespace handling

Layer / File(s)	Summary
Whitespace guard and test coverage stream-chat-android-ui-common/src/main/kotlin/io/getstream/chat/android/ui/common/feature/messages/composer/typing/TypingSuggester.kt, stream-chat-android-ui-common/src/test/kotlin/io/getstream/chat/android/ui/common/feature/messages/composer/typing/TypingSuggesterTest.kt	typingSuggestion returns null when the derived suggestion text begins with whitespace, and a parameterized test class checks matching and non-matching mention inputs.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

A tiny hop, a rabbit's grin 🐰
No leading space may sneak back in
@john may bloom, but @ must flee
Hop-hop! The suggester now agrees

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 33.33% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly matches the main bugfix: ignoring mention suggestions that begin with whitespace.
Description check	✅ Passed	The description includes Goal, Implementation, and Testing with enough detail for this bugfix, and the missing visual sections are not critical.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/mention-lookup-trim-whitespace-query

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[andremion]

LGTM!

One thing on cross-SDK parity: No iOS SDK has this leading-whitespace guard. Looks like the same bug exists on iOS. Should we file equivalent fixes on iOS so the behavior stays aligned?

Minor, not blocking: the Android check uses isWhitespace() (covers tabs and other Unicode whitespace), while iOS only treats " " and "\n" as separators. That difference is pre-existing, just noting it in case we want the platforms to classify edge inputs the same way.