rx.memo fixes to retain more API surface from the previous implementation

[masenf]

• allow bare annotations with warning -- treat as rx.Var wrapped
• allow no return annotation -- treat as rx.Component
• defer evaluation of memo functions to use/compile time
  • removed return annotation suggestion feature to reduce complexity; -> rx.Component will suffice
• add EMPTY_VAR_COMPONENT so that children args can have a default and don't need to be passed.

What is still outstanding?

• In some instances key, id, and/or other base Component props were accepted on the legacy rx.memo CustomComponent class. Now these require the RestProp. If there was a way to at least keep key working without a lot of hacks, that would be nice, since we have quite a bit of code in the wild that is using memo components with rx.foreach and need to be able to specify the react key. Obviously these can and should be rewritten to use RestProp, but I wonder if there's a way we can keep them working and throw up a deprecation warning?

[codspeed-hq]

Merging this PR will not alter performance

✅ 24 untouched benchmarks

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_{Comparing masenf/move-memo-fixups (3f9259a) with main (17e3392)}

[greptile-apps]

Greptile Summary

This PR extends @rx.memo with three capabilities: lazy body evaluation (deferred to first use / compile time instead of import time), backward-compatible coercion of bare Python-type annotations to rx.Var[...] with a deprecation warning, and a new rx.EMPTY_VAR_COMPONENT sentinel for optional children slots.

• Lazy evaluation — memo() no longer runs the decorated body; _ensure_definition_evaluated triggers evaluation on first get_component() / get_function() call, guarded by _evaluated / _evaluating flags mutated via object.__setattr__ on frozen dataclasses. Errors that previously surfaced at decoration time (bad return type, hook-bearing vars, non-bundled imports) now surface at compile time.
• Bare-annotation coercion — _analyze_params now detects non-Var / non-EventHandler annotations in public memo() calls and wraps them in Var[...], emitting a single deprecation warning so legacy memos keep working until 1.0.
• EMPTY_VAR_COMPONENT — defined in memo.py (not component.py) to avoid the circular import with reflex_base.environment, and exported as rx.EMPTY_VAR_COMPONENT; used immediately in skeleton_component for an optional children slot.

Confidence Score: 4/5

Safe to merge; the lazy-evaluation path is well-guarded and the test suite covers recursive memos, bare-type coercion, EMPTY_VAR_COMPONENT, and the deferred-error semantics for hook/import validation.

The only concerns are a non-atomic check-and-set of the _evaluating flag (benign in Reflex's single-threaded component creation but fragile for threaded callers) and an implicit contract on EMPTY_VAR_COMPONENT being used only for Var[Component]-typed parameters. Removal of _bind_self_reference is covered by the existing test_self_referencing_component_memo test which exercises the full compile path.

packages/reflex-base/src/reflex_base/components/memo.py — specifically _ensure_definition_evaluated and the new _evaluating flag mutation under concurrent access.

Important Files Changed

Filename	Overview
packages/reflex-base/src/reflex_base/components/memo.py	Core change: adds lazy evaluation via _ensure_definition_evaluated, drops _bind_self_reference, adds EMPTY_VAR_COMPONENT, and adds backward-compat coercion of bare-type annotations. The reentrancy guard is correct for module-level and closure-scoped self-referencing memos. Non-atomic check-and-set of _evaluating is a theoretical race condition but benign in Reflex's typical single-threaded component creation context.
tests/units/components/test_memo.py	Well-updated test suite: existing tests migrated from .component/.function direct access to .get_component()/.get_function(), new tests for lazy-eval behavior, bare-type coercion, EMPTY_VAR_COMPONENT, and hook/import validation now exercised via explicit compiler calls. test_self_referencing_component_memo (unchanged, outside the diff) continues to cover recursive component memos end-to-end.
packages/reflex-components-internal/src/reflex_components_internal/components/base/skeleton.py	Adds optional children slot to skeleton_component using EMPTY_VAR_COMPONENT as the default, allowing the skeleton to optionally wrap child content.
reflex/init.py	Adds EMPTY_VAR_COMPONENT to the lazy-loader mapping so it is accessible as rx.EMPTY_VAR_COMPONENT.
reflex/compiler/utils.py	Compiler updated to use definition.get_component() and definition.get_function() instead of direct field access, correctly triggering lazy evaluation at compile time.

_{Reviews (1): Last reviewed commit: "feat(memo): add rx.EMPTY_VAR_COMPONENT d..." | Re-trigger Greptile}

[FarhanAliRaza]

The component properties I allowed into memos maybe no op, have to test those. Key works that we need the most i think.
Edit: Only added key supprt instead of forwarding all props.