Avoid root dirty delta for shared state events

[harsh21234i]

Summary

• Preserve and restore root dirty state around the temporary router dirtying used by linked/shared state patching.
• Prevent regular linked-state events from sending an unchanged root/router delta.
• Add regression coverage for the issue described in Events against SharedState should not mark root state dirty all the time #6392.

Tests

• uv run --frozen pytest tests/units/test_state.py::test_linked_state_event_does_not_dirty_root_state -q
• uv run --frozen pytest tests/units/test_state.py::test_linked_state_event_does_not_dirty_root_state tests/units/test_state.py::test_router_var_dep tests/units/test_state.py::test_computed_var_depends_on_parent_non_cached tests/units/test_state.py::test_async_computed_var_get_state -q
• uv run --frozen pytest tests/units/test_state.py -q
• uv run --frozen pre-commit run --files reflex/istate/shared.py tests/units/test_state.py news/6392.bugfix.md

Closes #6392

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[codspeed-hq]

Merging this PR will not alter performance

✅ 26 untouched benchmarks
⏩ 8 skipped benchmarks¹

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_{Comparing harsh21234i:fix/shared-state-root-dirty-6392 (4a76d69) with main (333b78b)}

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. ↩

[greptile-apps]

Greptile Summary

The PR prevents temporary router dirtiness used during linked/shared-state patching from leaking into regular event deltas and now restores dirty-state bookkeeping when delta resolution fails.

• Snapshots root and descendant dirty-state sets before temporary router dependency resolution.
• Restores descendant bookkeeping after exceptional resolution and root bookkeeping on every non-full-delta exit.
• Adds regression tests for normal root cleanup and exceptional root/descendant cleanup.
• Adds bug-fix release notes.

Confidence Score: 5/5

The PR appears safe to merge.

No blocking failure remains; the current exception handler restores every pre-snapshotted descendant’s dirty sets, while the finally block restores the root dirty sets for failures and cancellations.

Important Files Changed

Filename	Overview
reflex/istate/shared.py	Preserves temporary dirty-state bookkeeping around linked-state delta resolution, including exception and cancellation paths.
tests/units/test_state.py	Adds focused regression coverage for normal root cleanup and exceptional root/descendant cleanup.
news/6841.bugfix.md	Documents the linked/shared-state dirty-delta fix.

_{Reviews (6): Last reviewed commit: "Restore descendant dirty state on linked..." | Re-trigger Greptile}

[cubic-dev-ai]

All reported issues were addressed across 3 files

<sub>Reply with feedback, questions, or to request a fix.

Fix all with cubic | Re-trigger cubic</sub>