v0.9.3 Pre-release Thread

[masenf]

Please report any problems you encounter in this discussion thread or as separate issues on reflex-dev/reflex.

pip install 'reflex~=0.9.3a'

Schedule

2026-05-20 18:15 PT: 0.9.3a1 pre-release published for testing
2026-05-21: Planned Public release of 0.9.3

Release Notes

Breaking Changes

• Lifespan tasks will now be passed an rx.App instance instead of a Starlette instance
  • fix(app): pass Reflex app instance to lifespan task app parameter by @BABTUNA in fix(app): pass Reflex app instance to lifespan task app parameter #6358

New Features

Persistent Frontend Dep Locking

Projects should commit the new reflex.lock directory which includes package.json and bun.lock. This helps avoid accidentally introducing upstream changes and helps protect against supply chain attacks.

• Respect root bun.lock during frontend installs by @GautamBytes in Respect root bun.lock during frontend installs #6289
• Move bun.lock under reflex.lock/bun.lock by @masenf in Move bun.lock under reflex.lock/bun.lock #6475

reflex cloud deploy --gcp

• feat(hosting-cli): add reflex cloud gcp deploy for Cloud Run by @Kastier1 in feat(hosting-cli): add reflex cloud gcp deploy for Cloud Run #6450

EmbedPlugin

With the EmbedPlugin, a Reflex frontend can now be mounted into an existing DOM element in a custom HTML page by simply including the entry point javascript.

• feat: support embedding Reflex apps into host pages via mount_target by @FarhanAliRaza in feat: support embedding Reflex apps into host pages via mount_target #6462

frontend_compression_formats

The build process now produces .gz sidecar files during export and serves them to supported clients for reflex run --env prod.

• feat: pre-compress frontend assets at build time by @FarhanAliRaza in feat: pre-compress frontend assets at build time #6497

Improvements

• fix(event): handle mixed rx.cond event/function returns in event lambdas by @BABTUNA in fix(event): handle mixed rx.cond event/function returns in event lambdas #6354
• fix(app): normalize subpath imports to install base npm package by @BABTUNA in https://github.com/reflex-dev/reflex/pull/6380\
• Remove redundant lost-and-found warning log by @masenf in Remove redundant lost-and-found warning log #6527
• fix(state.js): drop deprecated unload listener, use pagehide (Deprecated feature used #6195) by @ChinmayShringi in fix(state.js): drop deprecated unload listener, use pagehide (#6195) #6479

Bug Fixes

Compiler

• fix(memo): skip {children} hole substitution when wrapped component h… by @carlosabadia in fix(memo): skip {children} hole substitution when wrapped component h… #6466
• Allow overriding files with Plugins, just warn about it by @riebecj in Allow overriding files with Plugins, just warn about it #6476
• [codex] Fix memoized component hook prop rendering by @Alek99 in [codex] Fix memoized component hook prop rendering #6506
• [codex] fix foreach memo style cache by @Alek99 in [codex] fix foreach memo style cache #6513
• fix: use python truthiness for compiled and/or Var operations by @adhami3310 in fix: use python truthiness for compiled and/or Var operations #6546

CLI

• fix(hosting-cli): exit deploy when --envfile requires missing python-dotenv by @BABTUNA in fix(hosting-cli): exit deploy when --envfile requires missing python-dotenv #6414
• ENG-9522: Fix CLI: Lists projects as "Unknown" by @carlosabadia in ENG-9522: Fix CLI: Lists projects as "Unknown" #6530

Other Areas

• fix: Textarea enter_key_submit uses add_custom_code instead of _get_all_custom_code by @algojogacor in fix: Textarea enter_key_submit uses add_custom_code instead of _get_all_custom_code #6485
• fix(component): compare field values in BaseComponent.eq by @FarhanAliRaza in fix(component): compare field values in BaseComponent.__eq__ #6493
• fix: REFLEX_FRONTEND_PATH without leading slash duplicates path in logged URL by @qubydev in fix: REFLEX_FRONTEND_PATH without leading slash duplicates path in logged URL #6364
• fix: make Markdown a MemoizationLeaf so Var children stay inlined by @FarhanAliRaza in fix: make Markdown a MemoizationLeaf so Var children stay inlined #6532
• Expose rx.Plugin hook contexts by @masenf in Expose rx.Plugin hook contexts #6537
• ENG-9553: prepend frontend_path to RouterData.url and RouterData.page.raw_path by @masenf in ENG-9553: prepend frontend_path to RouterData.url and RouterData.page.raw_path #6535

Doc / Web

• add otp field to reflex components internal by @carlosabadia in add otp field to reflex components internal #6467
• ENG-9435: add .md files to deal with AI blindly adding .md by @adhami3310 in ENG-9435: add .md files to deal with AI blindly adding .md #6460
• Update router documentation for new URL API by @masenf in Update router documentation for new URL API #6371
• OPS-1430: Add what are you interested in option in demo form by @carlosabadia in OPS-1430: Add what are you interested in option in demo form #6459
• Update shared components for new web design by @carlosabadia in Update shared components for new web design #6474
• internal: Make the Demo Form Accept Extra on_submit Handlers by @amsraman in internal: Make the Demo Form Accept Extra on_submit Handlers #6486
• Update customers link in marketing navbar by @carlosabadia in Update customers link in marketing navbar #6487
• Small updates to footer and mobile navbar for web by @carlosabadia in Small updates to footer and mobile navbar for web #6492
• ENG-9484: update docs for auto setters by @adhami3310 in ENG-9484: update docs for auto setters #6496
• Show up to two lines per toc sidebar item by @carlosabadia in Show up to two lines per toc sidebar item #6502
• Update internal drawer component by @carlosabadia in Update internal drawer component #6523
• Remove accidental whitelist changes by @masenf in Remove accidental whitelist changes #6524
• Update docs whitelist workflow path and naming by @adhami3310 in Update docs whitelist workflow path and naming #6525
• reflex-site-shared: canonical override + Try-for-free primary CTA by @PalashAwasthi05 in reflex-site-shared: canonical override + Try-for-free primary CTA #6521
• Fix docs breadcrumb overview routes by @Alek99 in Fix docs breadcrumb overview routes #6441
• [codex] update README example sections by @Alek99 in [codex] update README example sections #6511
• AgentFilesPlugin writes md files to frontend_path subdir by @masenf in AgentFilesPlugin writes md files to frontend_path subdir #6536
• Fix feedback popover bg color by @carlosabadia in Fix feedback popover bg color #6540
• Bump base ui version for internal components by @carlosabadia in Bump base ui version for internal components #6541
• Fix mobile drawer internal links in marketing navbar by @carlosabadia in Fix mobile drawer internal links in marketing navbar #6539
• Refactor sidebar to use reactive Var operations instead of Python conditionals by @masenf in Refactor sidebar to use reactive Var operations instead of Python conditionals #6528
• Increase case study click area in navbar by @carlosabadia in Increase case study click area in navbar #6529
• update docs/app/reflex.lock by @masenf in update docs/app/reflex.lock #6543

Telemetry Improvements

• feat(telemetry): emit compile events with page/component/state breakdown by @FarhanAliRaza in feat(telemetry): emit compile events with page/component/state breakdown #6507
• feat(telemetry): report export status, duration, and phase timings by @FarhanAliRaza in feat(telemetry): report export status, duration, and phase timings #6509
• feat(telemetry): track per-feature usage counters on compile events by @FarhanAliRaza in feat(telemetry): track per-feature usage counters on compile events #6519
• feat: capture pre-init Python environment in init telemetry by @FarhanAliRaza in feat: capture pre-init Python environment in init telemetry #6534
• Display ToS / privacy warning on console with logging in by @masenf in Display ToS / privacy warning on console with logging in #6547
• add doc page for telemetry info and opt-out by @masenf in add doc page for telemetry info and opt-out #6548

Other Changes

• ENG-9447: add agents md instructions by @adhami3310 in ENG-9447: add agents md instructions #6461
• fix rx-shout integration test for new uv project structure by @masenf in fix rx-shout integration test for new uv project structure #6470
• added the missing tests (and verified they pass) by @patrizzzz in added the missing tests (and verified they pass) #6170
• use uv run --no-sync in pre-commit commands by @masenf in use uv run --no-sync in pre-commit commands #6472
• fix(test): make tailwind integration test rerun-safe by @masenf in fix(test): make tailwind integration test rerun-safe #6473
• test(perf): add Lighthouse benchmark suite and CI job by @FarhanAliRaza in test(perf): add Lighthouse benchmark suite and CI job #6494
• pin action commits by @adhami3310 in pin action commits #6498
• security hygiene on actions by @adhami3310 in security hygiene on actions #6499
• Pin some docs app components by @carlosabadia in Pin some docs app components #6501
• [codex] Loosen enterprise docs alert copy by @Alek99 in [codex] Loosen enterprise docs alert copy #6505
• Embed README example video by @Alek99 in Embed README example video #6508
• Update select docs by @tgberkeley in Update select docs #6503
• bump backend deps by @adhami3310 in bump backend deps #6488
• bump frontend deps 093 by @adhami3310 in bump frontend deps 093 #6489
• fix(make_pyi): also diff staged changes when scanning for pyi updates by @FarhanAliRaza in fix(make_pyi): also diff staged changes when scanning for pyi updates #6544

New Contributors

• @patrizzzz made their first contribution in added the missing tests (and verified they pass) #6170
• @amsraman made their first contribution in internal: Make the Demo Form Accept Extra on_submit Handlers #6486
• @algojogacor made their first contribution in fix: Textarea enter_key_submit uses add_custom_code instead of _get_all_custom_code #6485
• @PalashAwasthi05 made their first contribution in reflex-site-shared: canonical override + Try-for-free primary CTA #6521

Full Changelog: v0.9.2.post1...v0.9.3a1

[bertbarabas]

I was able to migrate two projects successfully and so far everything works well!

I'm not sure this is new but if you test one reflex app (on localhost), check it out on the browser, then kill the reflex app and test another one while the browser still has the first app showing you get a large number of the following exceptions:

Warning: Attempting to send delta to disconnected client 'd4dc3f98-084c-407f-e3ee-03220d6defc8'
[Reflex Frontend Exception]
 TypeError: dispatch is not a function
TypeError: dispatch is not a function
    at Socket.<anonymous> (http://localhost:3000/utils/state.js:685:27)
    at Emitter.emit (http://localhost:3000/node_modules/.vite/deps/socket__io-client.js?v=25e9766a:323:70)
    at Socket.emitEvent (http://localhost:3000/node_modules/.vite/deps/socket__io-client.js?v=25e9766a:2622:14)
    at Socket.onevent (http://localhost:3000/node_modules/.vite/deps/socket__io-client.js?v=25e9766a:2614:28)
    at Socket.onpacket (http://localhost:3000/node_modules/.vite/deps/socket__io-client.js?v=25e9766a:2588:10)
    at Emitter.emit (http://localhost:3000/node_modules/.vite/deps/socket__io-client.js?v=25e9766a:323:70)
    at http://localhost:3000/node_modules/.vite/deps/socket__io-client.js?v=25e9766a:3173:9

[masenf]

it's a known issue #6019; a fix was posted in #6128 but it was a drive by and changed more than necessary. but we would like to land a fix in this area eventually.

[masenf]

v0.9.3 is released! 🎉