✂️ fix: Trim Reasoning Tags from Titles and Delete Button Visibility

[poornapragnyah]

Summary

Fixes #10284

This PR fixes a bug where LLM reasoning tags (e.g., <think>...) are incorrectly saved as chat titles, particularly when using models like qwen3:8b on Ollama. This pollutes the database and causes a UI bug where the "Delete Conversation" modal overflows, hiding the "Delete" button.

This fix is in two parts:

1. Backend (Root Cause): A new sanitizeTitle utility is added to packages/api to strip all <think>...</think> blocks from new titles before they are saved. This is integrated into the api/server/controllers/agents/client.js controller.
2. Frontend (Defensive Fix): The delete modal (client/src/components/Conversations/ConvoOptions/DeleteButton.tsx) is updated with truncate w-full. This defensively handles any existing malformed titles already in the database, preventing the UI overflow.

Change Type

• Bug fix (non-breaking change which fixes an issue)

Testing

I performed both automated and manual testing for this two-part fix.

Backend Testing (Automated):

1. Created a new utility packages/api/src/utils/sanitizeTitle.ts.
2. Created a new test file packages/api/src/utils/sanitizeTitle.spec.ts with 34 new unit tests covering all edge cases (stripping, case-insensitivity, attributes, fallbacks, etc.).
3. Updated api/server/controllers/agents/client.js with 2 new integration tests to verify the sanitizeTitle function is correctly called.
4. Result: All backend unit and integration tests passed.

Frontend Testing (Automated & Manual):

1. Automated: All automated frontend test cases passed, confirming the changes did not introduce any regressions.
2. Manual (Fix for new chats):
   • Started a new chat with the qwen3:8b model.
   • Verified: The title generated in the sidebar was clean (e.g., "User Hi Greeting") and did not contain <think> tags.
3. Manual (Fix for old chats):
   • Located an existing chat with a malformed title (<think>...).
   • Clicked the "Delete" button.
   • Verified: The modal appeared correctly. The title was truncated (e.g., This will delete <think>...), and the "Delete" button was visible and clickable.

Test Configuration:

• OS: Fedora 41
• Browser: Brave 1.83.112
• Endpoint: Ollama (Custom Endpoint)
• Model: qwen3:8b (to reproduce the bug)

Checklist

• My code adheres to this project's style guidelines
• I have performed a self-review of my own code
• I have commented in any complex areas of my code (JSDoc for sanitizeTitle)
• I have made pertinent documentation changes (N/A for this fix)
• My changes do not introduce new warnings
• I have written tests demonstrating that my changes are effective or that my feature works
• Local unit tests pass with my changes
• Any changes dependent on mine have been merged and published in downstream modules.
• A pull request for updating the documentation has been submitted.