Event processor fix

[benedikt-bartscher]

No description provided.

[codspeed-hq]

Merging this PR will not alter performance

✅ 27 untouched benchmarks
⏩ 8 skipped benchmarks¹

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_{Comparing benedikt-bartscher:event-processor-fix (cbccaad) with main (f7c848f)²}

Footnotes

1. 8 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

2. No successful run was found on main (45b8ed5) during the generation of this report, so f7c848f was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

[greptile-apps]

Greptile Summary

This PR fixes a RuntimeError crash that occurred when an event was chained from a parent event handler that had already completed. The fix adds a not parent_future.done() guard before calling parent_future.add_child(tracked), allowing late-chained events to proceed independently rather than crashing.

• The ordering of checks is correct: the existing cancelled() early-return is evaluated first, so the new done() guard specifically covers parent futures that completed with a result or exception; the late-chained child still gets enqueued and executes normally.
• The regression test directly reproduces the failure scenario by inserting a pre-completed EventFuture and asserting no crash, correct execution of the late child, and an empty children list on the done parent.

Confidence Score: 5/5

• This is a small, targeted guard in the event-enqueue path that prevents a crash without altering any other behaviour.
• The change is minimal and well-understood: one conditional wrapping a single method call, backed by a direct regression test that covers the exact failure scenario. Callers who awaited the parent via wait_all() before the late child was enqueued won't see any change; callers who crashed before will now succeed. No data-path side effects were introduced.
• No files require special attention.

Important Files Changed

Filename	Overview
packages/reflex-base/src/reflex_base/event/processor/event_processor.py	Adds a not parent_future.done() guard before add_child, preventing a RuntimeError when a late-chained event tries to register under an already-completed parent future. Logic is correct: cancelled futures are handled first (early return), so the new check only fires when the parent completed with a result or exception.
tests/units/reflex_base/event/processor/test_event_processor.py	Adds a targeted regression test that manually inserts a completed parent EventFuture into the processor's _futures dict and verifies (1) no crash, (2) the late-chained event actually executes, and (3) the done parent's children list stays empty.
packages/reflex-base/news/6801.bugfix.md	Changelog entry accurately describes the fixed crash and the new behaviour for late-chained events.

_{Reviews (3): Last reviewed commit: "add changelog" | Re-trigger Greptile}

[cubic-dev-ai]

No issues found across 3 files

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