fix(web): resolve chat message loading race conditions and infinite loops

[MkDev11]

Summary

Fix chat message loading race conditions, log disorder, and infinite loops in the app log panel.

Fixes #30259

Changes:

• Add AbortController to cancel in-flight requests on new scroll
• Add requestIdRef to ignore stale responses
• Add oldestAnswerIdRef to store pagination anchor in ref (avoids stale closures)
• Add lastLoadTimeRef for throttling that persists across effect re-runs
• Add retryCountRef with MAX_RETRY_COUNT=3 to prevent infinite retry loops
• Remove duplicate scroll listener that was firing both fetchData and loadMoreMessages
• Use functional state updates in setAllChatItems to avoid stale state issues

Checklist

• This change requires a documentation update, included: Dify Document
• I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• I've updated the documentation accordingly.
• I ran make lint and make type-check (backend) and cd web && npx lint-staged (frontend) to appease the lint gods

---

Contribution by Gittensor, see my contribution statistics at https://gittensor.io/miners/details?githubId=94194147

[gemini-code-assist]

Summary of Changes

Hello @MkDev11, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses critical issues within the chat message loading mechanism in the app log panel, specifically targeting race conditions, log disorder, and infinite loops. By introducing robust request management, state synchronization, and retry logic, the changes significantly improve the stability and reliability of message loading and pagination, leading to a smoother user experience.

Highlights

• Request Cancellation: Implemented AbortController to cancel in-flight requests during new scroll events, preventing race conditions.
• Stale Response Handling: Added requestIdRef to ensure only the latest request's response is processed, effectively ignoring stale or out-of-order responses.
• Pagination Anchor: Introduced oldestAnswerIdRef to store the pagination anchor, resolving stale closure issues and ensuring consistent message loading.
• Throttling Persistence: Utilized lastLoadTimeRef for scroll throttling that maintains state across component re-renders, preventing excessive API calls.
• Infinite Loop Prevention: Added retryCountRef with a MAX_RETRY_COUNT of 3 to prevent infinite retry loops that could occur during message loading under certain conditions.
• Duplicate Scroll Listener Removal: Eliminated a redundant scroll listener that was causing fetchData and loadMoreMessages to fire simultaneously, simplifying logic and preventing unnecessary calls.
• Stale State Resolution: Switched to functional state updates for setAllChatItems to avoid issues with stale state, ensuring data consistency when updating the chat message list.

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[gemini-code-assist]

Code Review

This pull request refactors the chat message loading and pagination logic within the DetailPanel component. Key changes include implementing request cancellation using AbortController and requestIdRef to prevent race conditions and ignore stale responses, and introducing oldestAnswerIdRef for a more robust pagination strategy to avoid stale closure issues. The loadMoreMessages function was enhanced with throttling using lastLoadTimeRef and a retry mechanism (retryCountRef, MAX_RETRY_COUNT) to improve scroll-based loading reliability, especially when no new unique messages are immediately available. Additionally, the scroll event listener was simplified, and state updates for allChatItems were converted to functional updates. The review comment points out a React anti-pattern where other state setters (setChatItemTree, setThreadChatItems) and ref updates (oldestAnswerIdRef) are performed inside the setAllChatItems functional updater. The reviewer suggests moving this logic into a separate useEffect hook that depends on allChatItems and hasMore to ensure the purity of the updater function and proper state management.

[crazywoola]

Please add a test for it as well :) The rest LGTM

[MkDev11]

Please add a test for it as well :) The rest LGTM

Done!

[crazywoola]

Please fix the lint errors.

[MkDev11]

@crazywoola Could you please merge the PR?

[crazywoola]

We will review this later :)