fix: flatten providers for large state trees by harsh21234i · Pull Request #7441 · reflex-dev/reflex

harsh21234i · 2026-10-06T05:36:28Z

Summary

Flatten the state provider tree on both the client and server. A single shared state-store context keeps provider depth independent of the number of substates, including during development SSR.

Generated state reads subscribe to their substate with useSyncExternalStore. A delta applies immutably to only that substate and notifies only its subscribers, avoiding a full state-map copy or rebuilding all provider elements on every update. The external-store hook gives React consistent snapshots during concurrent rendering; the store is changed only by event dispatch, never during render.

Testing

Focused context, compiler, memoization, and component tests: 361 passed, 1 skipped, 1 excluded because the local environment lacks the optional Plotly dependency.
Includes a Node runtime test that traverses an SSR tree with 5,000 substates and a client test that verifies targeted notification and unchanged-state identity.
Focused Ruff checks and git diff --check passed.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

greptile-apps · 2026-10-06T05:39:12Z

Confidence Score: 5/5

[High impact] The PR appears safe to merge; the outstanding hot-refresh finding is fixed.

Summary

The PR replaces nested state providers with one shared store, keeping provider depth constant as the state tree grows.

State providers stay shallow as an app adds state classes.
State updates reach only readers of the changed substate.

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codspeed · 2026-10-06T05:46:24Z

Merging this PR will not alter performance

⚠️

16 benchmarks spent significant time in system calls

System calls cannot be consistently instrumented, so they are not included in the measure, which understates the real cost. Please switch to the Walltime instrument to accurately measure system calls.

Measurement and system calls

test_import_cli

test_get_state[disk]

test_get_state_uncached[disk]

test_set_state[disk]

test_cli_startup[run_help]

test_cli_startup[cloud_help]

test_modify_state[disk]

test_cli_startup[help]

test_cli_startup[version]

test_state_manager_memory_modify

…and 6 more

✅ 148 untouched benchmarks

_{Comparing harsh21234i:harsh21234i-fix-large-state-tree (3084bc4) with main (2fc4a9c)}

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

FarhanAliRaza

Requesting changes. See the inline comments.

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harsh21234i · 2026-10-14T06:21:12Z

The fix for #7429 replaces the per-substate providers with a shared store. The compiler rewrite preserves legacy reads in compiled Reflex code, but it cannot rewrite independently bundled third-party components using useContext(StateContexts.foo). Is that raw context access a supported compatibility surface? I’d like to confirm before adding a compatibility path that could bring back the provider-depth problem.

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masenf · 2026-10-14T07:05:23Z

Is that raw context access a supported compatibility surface?

No, accessing the state content directly via javacript not generated by the reflex compiler is not a supported path.

Drop the compile-time JavaScript rewriter that turned useContext(StateContexts.x) into a shared-store read. Reflex now generates useStateContext(...) for every state read on each compile, so the rewriter only served hand-written hooks. It missed dynamic components and asset JS, where legacy reads silently became null. Remove the StateContexts export and getStateContext as well, so any remaining legacy read fails the build with a missing-export error instead of reading null. Add a breaking news fragment with the migration to useStateContext.

FarhanAliRaza · 2026-10-14T16:30:45Z

I pushed 6f0117c. It removes the legacy StateContexts rewriter.

Why:

Reflex now generates useStateContext(...) for every state read on each compile. The rewriter only served hooks that users type by hand.
StateContexts is internal. It is not documented and not public API, so it needs no compatibility layer.
The rewriter missed two paths. A legacy read in a dynamic component and a legacy read in an asset .jsx file both read null with no error.
It added a 300-line JavaScript lexer to every compile.

What changed:

Removed _rewrite_legacy_state_context_reads, _mask_javascript_literals_and_comments, and their tests.
Removed StateContexts, getStateContext, and useLegacyStateContext. A leftover legacy read now fails the build with "StateContexts" is not exported by "utils/context.jsx". It no longer reads null silently.

Tested: an app with 3000 extra states renders with no errors. A delta still re-renders only the components that read the changed substate. The focused unit tests, ruff, and pyright pass.

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- Raise reflex's reflex-base floor to 0.10.1.dev0: code_uses_state_contexts looks for useStateContext(, which only the new reflex-base generates. - Drop the unrelated greenlet change in examples.yml. - Compare applyDelta's result with the current state instead of pre-checking the delta, so a deep-equal delta no longer notifies. - Skip syncInitialState when the store already holds that initial state. - Serve the server render from a read-only store. - Remove the duplicate listener set creation and use one useMemo in useStateContext. - Mark the news fragments as bugfix with per-package text. - Make the JS store test use a structural-sharing applyDelta stub, subscribe by state name, and cover an equal list delta.

FarhanAliRaza · 2026-10-14T17:19:43Z

I pushed 1455221. It addresses the review findings on the shared state store:

reflex now requires reflex-base >= 0.10.1.dev0. code_uses_state_contexts looks for useStateContext(, which only the new reflex-base generates.
The greenlet change in examples.yml is reverted. It is not related to this PR.
The dispatcher now compares the result of applyDelta with the current state. applyDelta already keeps the old object for equal values, so the separate pre-check is gone. A deep-equal delta, for example an equal list, no longer calls listeners.
syncInitialState returns early when it gets the initial state the store already holds. On mount, it no longer walks every field of every substate.
The server provider uses a read-only store. It no longer builds dispatchers and listener sets on each server render.
registerSubstate no longer creates listener sets. subscribe creates them when needed.
useStateContext uses one useMemo instead of two useCallback calls.
The news fragments are now bugfix, with separate text for reflex and reflex-base.
The JS store test uses an applyDelta stub that shares structure like the real one. It subscribes by state name, not by array index, and it checks that an equal list does not notify.

Tested: in a test app, the render count of each component is the same as on the previous head. Hot reload still adds new states and fields. The focused unit tests, ruff, pyright, and check_min_deps for reflex pass.

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masenf

i really like this idea. it reduces the number of contexts and useState calls overall and it opens the door eventually for per-var subscriptions.

Attach the test listeners through the subscribe callback the hook passes to useSyncExternalStore, so the test fails if the hook subscribes to the wrong substate.

createStateStore takes the initial state and registers substates through one addSubstates path, which hot reload calls for the substates of new state classes. Fields added to existing substates are not merged here: they arrive with the hydrate delta after the backend restarts.

mergeInitialState adds new substates and gives existing substates the fields of the recompiled initial state at their defaults, keeping live values. A substate is replaced and notified only when it gains a field, so the mount-time call changes nothing.

fix: reduce client state provider nesting

dbcefc2

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

harsh21234i requested a review from a team as a code owner October 6, 2026 05:36

greptile-apps Bot reviewed Oct 6, 2026

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fix: avoid copying all client substates per delta

422610f

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

masenf added the bug Something isn't working label Oct 6, 2026

FarhanAliRaza requested changes Oct 7, 2026

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fix: flatten large state provider trees

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harsh21234i changed the title ~~fix: reduce client state provider nesting~~ fix: flatten providers for large state trees Oct 8, 2026

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harsh21234i added 3 commits October 8, 2026 12:56

fix: address state provider review feedback

ef50437

docs: add PR 7441 performance news fragment

8543148

docs: add reflex package performance news fragment

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docs: use valid orphan news fragment name

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masenf added the on deck PRs lined up to review / merge next label Oct 9, 2026 — with ChatGPT Codex Connector

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fix: preserve legacy state context reads

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Merge main into large state tree PR

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fix: keep legacy state context reads compatible

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masenf added 2 commits October 10, 2026 02:57

Fix compiler pre-commit checks for legacy context rewrite

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Merge main into flat state provider PR

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Merge branch 'main' into harsh21234i-fix-large-state-tree

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Install greenlet in legacy playground check

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Address PR 7441 review feedback

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Fix remaining PR 7441 review findings

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harsh21234i requested a review from Alek99 as a code owner October 14, 2026 06:57

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harsh21234i and others added 2 commits October 14, 2026 12:45

Fix legacy state read scanning and rewriting

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chore: drop breaking fragment for internal StateContexts removal

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FarhanAliRaza added 2 commits October 14, 2026 22:26

test: subscribe through useStateContext in the store test

99f9ed8

Attach the test listeners through the subscribe callback the hook passes to useSyncExternalStore, so the test fails if the hook subscribes to the wrong substate.

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FarhanAliRaza approved these changes Oct 15, 2026

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FarhanAliRaza mentioned this pull request Oct 15, 2026

enable_state=False guard (code_uses_state_contexts) misses memoized state reads #7579

Open

FarhanAliRaza merged commit 81f463b into reflex-dev:main Oct 15, 2026
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FarhanAliRaza mentioned this pull request Oct 16, 2026

perf: re-render state readers only when a field they read changes #7583

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Confidence Score: 5/5

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Merging this PR will not alter performance

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harsh21234i commented Oct 14, 2026

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