🗂️ refactor: Split useEventHandlers by Responsibility

[berry-13]

Pull Request

Before submitting, please review the Contributing Guide.

Documentation changes belong in the LibreChat documentation repository.

Summary

useEventHandlers.ts (1,352 lines) held every handler the chat stream renders through: the turn-opening ones (legacy text, sync, created, title), the final handler, the error, cancel and abort paths, the pure error-turn builders, and the setup that wires the step, content and attachment handlers. One file for all of it made each handler hard to review and kept the file far over the chat package's size budget.

This splits it by responsibility in client/src/hooks/SSE/: turns.ts (the error-turn builders and the conversation title rule), useTurnHandlers (text, sync, created, title), useFinalHandler (the final handler and the early-abort restore), and useAbortHandlers (error, cancel and abort). They share one EventHandlerContext (handlers.ts) that useEventHandlers builds from the values it already read; useEventHandlers.ts keeps that setup and is now 277 lines, every new file under 400. No behavior changes. Stacked on #17134.

Open PRs #17020 and #16451 touch finalHandler and the subagent reset in this file; their changes apply unchanged to the moved code in useFinalHandler.ts and useEventHandlers.ts.

Type of change

• Refactor

Testing

Tested environments/configuration:

Not applicable: the handlers are moved, not changed.

Automated tests:

• useEventHandlers.spec.ts imports resolveErrorTurn from turns.ts; nothing else in the specs changed.
• In client, the hooks/SSE specs (useEventHandlers, its cancel spec, titles, workspace, useResumableSSE, transport) plus hooks/Chat and data-provider/SSE: 1148 pass.
• npx tsc --noEmit in client, eslint, prettier and sort-imports on the changed files: clean.

Screenshots / recordings

No user-facing change.

Risk / compatibility

None.

Checklist

• I reviewed my own changes
• Existing relevant tests pass
• The change does not introduce new warnings or errors

[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-16T19:41:54.019570Z	8f31f21	New commits
🔒 Security Review	✅ Completed 2026-10-15T07:24:05.083857Z	c1024f9	PR opened

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