Fuse snapshot memo subtree walks into one traversal

[Alek99]

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Type of change

• Performance improvement (non-breaking change, identical compile output)

Changes To Core Features:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your core changes, as applicable?

What this does

Compiling a snapshot memo definition (compile_experimental_component_memo, non-passthrough branch) walked the deep-copied subtree four separate times — _get_all_hooks, _get_all_custom_code, _get_all_dynamic_imports, _get_all_imports — each independently recursing children and prop components, and re-calling per-node getters like _get_components_in_props once per artifact. Snapshot memos dominate rx.foreach-heavy pages, so these redundant traversals multiply.

Fix

New _collect_subtree_artifacts gathers all four artifacts in a single traversal. Correctness is order-sensitive (hooks/custom-code dict insertion order determines the emitted JS), so the fused walk reproduces each legacy recursion's exact per-node combination order:

• hooks: internal → own → added → children, and never from prop subtrees (an in_prop_tree flag mirrors _get_all_hooks skipping prop edges entirely);
• custom code: own → prop subtrees → own add_custom_code → children (the interleaving _get_all_custom_code uses);
• dynamic imports: set semantics, order-free;
• imports: self → children → props, via the same merge_parsed_imports.

The fused walk runs before render() so add_hooks side effects (derived props) land first, matching the legacy hooks-walk-then-render order (the passthrough branch already collects imports before render).

Scoping note

The ticket also covers the tag-hash walks (_get_component_hash). Those are entangled with the known _get_all_hooks_internal shared-cache mutation bug (ENG-10108): today's hash output can depend on cache pollution from prior walks, so a fused hash walk can't be verified byte-identical until that bug is fixed. Deferred to a follow-up after ENG-10108; this PR takes the definition-compile side, which is pollution-free.

Verification

• New order-sensitive equivalence test: a tree exercising hooks, internal (ref) hooks, per-instance custom code, class-level add_custom_code, dynamic imports, component-typed prop slots, and nested prop-subtree children asserts the fused walk's four results equal the four legacy recursions including dict key order, and that prop-subtree hooks don't leak out.
• CodSpeed instrumentation on this PR is the authoritative before/after CPU measurement (this sandbox has no PyPI egress for local profiling); numbers will be posted here once the run completes — test_compile_*[_stateful_page] exercises snapshot memos via rx.foreach.

Part of a compiler-performance series; tracked in Linear as ENG-10105.

🤖 Generated with Claude Code

https://claude.ai/code/session_01Jy8uHH11KircGa2MbTrR8g

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Generated by Claude Code

[greptile-apps]

Greptile Summary

This PR combines snapshot memo artifact collection into one subtree traversal. The main changes are:

• Adds a fused collector for hooks, custom code, dynamic imports, and imports.
• Uses the collector while compiling non-passthrough snapshot memos.
• Adds order-sensitive equivalence tests and a performance changelog.

Confidence Score: 4/5

Artifact collection can run before state needed by custom-code and import getters is established.

• The old path completed descendant hook side effects before evaluating other artifacts.
• The old path also rendered the tree before collecting custom code and imports.
• The new test does not cover getters that depend on either lifecycle step.

reflex/compiler/utils.py and tests/units/compiler/test_compiler_utils.py

Important Files Changed

Filename	Overview
reflex/compiler/utils.py	Adds the fused traversal, but changes when non-hook artifacts are evaluated relative to descendant hook side effects and rendering.
tests/units/compiler/test_compiler_utils.py	Adds detailed ordering tests, but only compares collectors on an unrendered tree with static artifact getters.
news/6748.performance.md	Documents the snapshot memo traversal optimization.

_{Reviews (1): Last reviewed commit: "Add news fragment for snapshot memo walk..." | Re-trigger Greptile}

[greptile-apps]

Artifact Collection Runs Too Early

The legacy path completed the full hooks walk and render() before collecting custom code, dynamic imports, and imports. The fused depth-first call now evaluates a parent’s artifact getters before descendant add_hooks side effects and before rendering, so components that derive artifact requirements from those updates can emit stale custom code or omit required imports.

[codspeed-hq]

Merging this PR will not alter performance

✅ 26 untouched benchmarks
⏩ 8 skipped benchmarks¹

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_{Comparing claude/reflex-compiler-perf-t8ztc9-15-snapshot-memo-walks (82b57dd) with main (9a5c4d3)}

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. ↩

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Include VarData component artifacts in fused walk

This fused traversal only descends structural children here (and component props above), but Bare overrides the legacy _get_all_custom_code and _get_all_dynamic_imports to also visit components stored on its contents VarData. After the snapshot memo path replaces the legacy walkers with this helper, a memo body containing a component Var/Bare such as a conditional branch with a NoSSRComponent or a component that returns _get_custom_code() will omit that dynamic import or custom code from the generated memo module, even though the rendered JSX still references it. Please preserve the VarData component edge (or otherwise delegate to the override behavior) when fusing the walk.

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