ENG-9425: fixes for extensible BaseState

[masenf]

• For overridden methods, do not create EventHandler wrappers
• For descriptor fields in a State, add a placeholder in vars, but do not intercept their access/set patterns.

[linear]

ENG-9425 rx.state._override_base_method still creates an EventHandler for the overridden method

[codspeed-hq]

Merging this PR will not alter performance

✅ 9 untouched benchmarks

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_{Comparing masenf/extensible-state (ccb74a2) with main (c36ac89)}

[greptile-apps]

Greptile Summary

This PR introduces two fixes for extensible BaseState: (1) methods decorated with @_override_base_method are no longer wrapped as EventHandlers, and (2) custom descriptors defined on a state class are registered in cls.vars as lightweight placeholder Vars (via a new descriptor_vars dict) so computed vars can declare dependencies on them, while is_backend_base_variable is updated to exclude such descriptors from backend-var storage.

• The new test at line 4694 asserts \"_desc_value\" in DescriptorState.base_vars, but _desc_value starts with _ and is explicitly excluded from base_vars by the not name.startswith(\"_\") filter; descriptors land only in descriptor_vars → cls.vars. This assertion will fail and block CI.

Confidence Score: 3/5

Not safe to merge until the incorrect base_vars assertion in the new test is fixed — it will fail CI.

A P1 test bug (base_vars assertion for an underscore-prefixed descriptor) will cause the new test to fail immediately. The production logic in state.py and types.py is otherwise sound.

tests/units/test_state.py — line 4694 has an incorrect assertion that will fail CI.

Important Files Changed

Filename	Overview
tests/units/test_state.py	Two new tests added; the descriptor test contains an incorrect base_vars assertion (line 4694) that will fail because _desc_value starts with _ and is excluded from base_vars.
reflex/state.py	Adds _is_user_descriptor helper and descriptor_vars collection; skips EventHandler wrapping for __override_base_method__-marked functions. Logic is sound with the caveat that child descriptors silently reuse the parent's Var.
packages/reflex-base/src/reflex_base/utils/types.py	Adds a __get__ check in is_backend_base_variable so custom descriptors are excluded from backend-var storage; straightforward and correct.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[BaseState.__init_subclass__] --> B[Compute base_vars\nfrom pydantic fields\nnot starting with _]
    A --> C[Iterate mixins + cls\nfor descriptor_vars]
    C --> D{_is_user_descriptor?}
    D -- No --> E[skip]
    D -- Yes --> F[Create placeholder Var\nwith FIELD_MARKER]
    F --> G[descriptor_vars dict]
    G --> H[cls.vars merge\ndescriptor_vars + inherited_vars\n+ base_vars + computed_vars]
    B --> H
    A --> I[_item_is_event_handler check]
    I --> J{__override_base_method__?}
    J -- Yes --> K[skip — not an EventHandler]
    J -- No --> L[wrap as EventHandler]
    A --> M[_init_var_dependency_dicts\nregisters computed var deps\nagainst descriptor_vars entries in cls.vars]

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_{Reviews (1): Last reviewed commit: "ENG-9425: fixes for extensible BaseState" | Re-trigger Greptile}

[greptile-apps]

Incorrect base_vars assertion — test will fail

_desc_value starts with _, so it is explicitly excluded from base_vars by the not name.startswith("_") guard in __init_subclass__. Descriptor vars are added only to descriptor_vars, which is then merged into cls.vars. The assertion on line 4694 will therefore always be False and the test will fail.

The comment on line 4693 says "visible in base_vars/vars", but only the vars half is correct; the base_vars assertion should be inverted (or simply removed).

Suggested change

	# But it should be visible in base_vars/vars for dependency tracking.
	assert "_desc_value" in DescriptorState.base_vars
	# But it should be visible in vars for dependency tracking.
	assert "_desc_value" not in DescriptorState.base_vars
	assert "_desc_value" in DescriptorState.vars

[greptile-apps]

Child override of parent descriptor silently uses parent Var

When a subclass overrides a parent's descriptor with a different implementation, dname in cls.inherited_vars is True (because the parent's placeholder Var was merged into parent_state.vars, which becomes inherited_vars). The child's descriptor is therefore skipped and the dependency-tracking Var still refers to the parent-state field name in its VarData. Any computed var in the child that depends on the overridden descriptor would be attached to the parent's tracking dict rather than the child's, potentially missing invalidation.

This may be an accepted limitation, but it would be worth a comment or a # TODO to document the behaviour for future readers.