fix(patches): register the live-markdown parser worklet in an insertion effect by dariusz-biela · Pull Request #102415 · Expensify/App

dariusz-biela · 2026-09-28T12:04:25Z

PR Stack

Follow-up to #101577, which fixed the React Native renderer so Fabric runs the insertion effect cleanup for a subtree removed while hidden. This PR carries the library change as a patch and relies on that renderer patch.

Explanation of Change

Patches @expensify/react-native-live-markdown@0.1.336 with the fix from Expensify/react-native-live-markdown#776: the parser worklet is registered in useInsertionEffect instead of during render, so the native input keeps formatting markdown after React remounts its effects. The upstream PR is on hold until the library can rely on React Native 0.88, which is why the change ships as a patch.

In the app

MarkdownTextInput on iOS and Android keeps formatting markdown after its screen was hidden behind an <Activity> and shown again, and under StrictMode in development. Before, the input silently lost its parser and rendered plain text from then on.
No change on web, the web input is not part of the patch.

In the code

patches/@expensify/react-native-live-markdown/…+001+register-parser-worklet-in-insertion-effect.patch carries the src/, lib/ and native (cpp/, apple/, android/) parts of the upstream PR. The parser id is chosen in JS, one per mounted input and a fresh one on every parser change, and registered in a new useParserId hook. The native registry becomes a plain map from id to worklet. A parse for an id with no registered worklet logs a warning and returns no ranges without caching them, so the next parse picks the parser up once it is registered.
patches/@expensify/react-native-live-markdown/details.md documents the patch and its dependency on the renderer patch from fix(patches): run the useInsertionEffect cleanup of a component removed inside a hidden Activity #101577: without it Fabric skips the insertion cleanup for an input removed while hidden and the worklet leaks in the native registry.

Note

This case is unreachable in practice, but it is possible in theory, so I'm noting it here. On a parser change or unmount, the insertion cleanup unregisters the old id during the JS commit, a moment before the native view receives the new parserId. A parse that runs on the UI thread inside that window finds no worklet, logs a No parser registered warning and returns no ranges for that single parse. The next parse formats the text again. I could not trigger it on the iOS simulator, even with fast typing right after a filter swap in the search router.

Fixed Issues

$ #98254
PROPOSAL: N/A (internal fix)

Tests

The bug is latent on main: no markdown input sits under a hidden <Activity> and StrictMode is off, so the dev steps turn on StrictMode, which disconnects and reconnects effects on every mount the same way a hidden <Activity> does. The patch changes native code, so rebuild the app after npm install.

Run npm install and verify that patch-package lists @expensify/react-native-live-markdown@0.1.336 (1 register-parser-worklet-in-insertion-effect) with a check mark and no warning.
Set USE_REACT_STRICT_MODE_IN_DEV to true in src/CONFIG.ts, rebuild and start the app on iOS and Android. Open a report and type Hello *bold* _italic_ ~strike~ `code` https://expensify.com in the composer. Verify that every style and the link render as you type. On main with the same flag the composer shows plain text only.
Send the message, open another report and come back. Type *again* in the composer and verify that it renders bold.
Open the search router, type from: and pick a person from the suggestions. Verify that the filter is highlighted. Delete the picked value, pick a different person and verify that the new filter is highlighted too. Each change gives the input a new parser, so this checks that a parser swap keeps formatting.
Revert src/CONFIG.ts, run the app on web and repeat step 2. Verify that formatting works as before, since the web input is not part of the patch.

Verify that no errors appear in the JS console

Offline tests

N/A. The patch only changes when the markdown parser is registered on the native side, no network or Onyx code is involved.

QA Steps

Regression pass on the normal build, with no StrictMode and no <Activity>. Run it on iOS and Android native, and steps 1 and 2 on mWeb and desktop web.

Open a report and type Hello *bold* _italic_ ~strike~ `code` https://expensify.com in the composer. Add a code block, a quote (> quote), a heading (# heading), a mention of another member and an emoji. Verify that everything is formatted as you type.
Send the message. Verify that the composer clears and formats the next text you type.
Edit the sent message. Verify that the edit composer shows the formatting and keeps formatting while you change the text.
Go to Search, then Settings, then back to the report. Type *bold* in the composer and verify that it renders bold.
Open the search router, type type:expense from: and pick a person from the suggestions. Verify that both filters are highlighted, then replace the picked person and verify that the highlighting follows.

Verify that no errors appear in the JS console

PR Author Checklist

Screenshots/Videos

Android: Native

Dev tests (With React Strict Mode):

5-tests-android-markdown-formatting.mp4

QA tests (Without React Strict Mode):

6-qa-steps-android-markdown-formatting.mp4

iOS: Native

Dev tests (With React Strict Mode):

3-tests-ios-markdown-formatting.mp4

QA tests (Without React Strict Mode):

4-qa-steps-ios-markdown-formatting.mp4

MacOS: Chrome / Safari

Dev tests (With React Strict Mode):

1-tests-web-markdown-formatting.mp4

QA tests (Without React Strict Mode):

2-qa-steps-web-markdown-formatting.mp4

…on effect MarkdownTextInput registered its parser worklet during render and dropped the registration in an effect cleanup, which React runs without unmounting the component under StrictMode and for a hidden Activity. The native view then held a parser id that pointed at nothing and the input stopped formatting markdown. The patch carries Expensify/react-native-live-markdown#776 for 0.1.336: the id is chosen in JS per mounted input and registered in useInsertionEffect, and the native registry is a plain map that returns no ranges for an unknown id. The upstream PR is on hold until the library can rely on React Native 0.88; the insertion cleanup it depends on comes from the react-native patch in the previous commit.

The upstream PR now makes a parse for an id with no registered worklet log a warning and return no ranges without caching them, on both iOS and Android, instead of silently returning an empty result. The patch carries that change, which also touches apple/MarkdownParser.h and the Android MarkdownParser.java.

github-actions · 2026-09-28T12:04:39Z

⚠️ This PR is possibly changing native code and/or updating libraries, it may cause problems with HybridApp. Please check if any patch updates are required in the HybridApp repo and run an AdHoc build to verify that HybridApp will not break. Ask Contributor Plus for help if you are not sure how to handle this. ⚠️

melvin-bot · 2026-09-29T10:16:11Z

@truph01 Please copy/paste the Reviewer Checklist from here into a new comment on this PR and complete it. If you have the K2 extension, you can simply click: [this button]

truph01 · 2026-10-06T09:42:00Z

@dariusz-biela Could we add a test like InsertionEffectCleanupInHiddenActivityTest that renders MarkdownTextInput under StrictMode and a hidden/shown <Activity> and checks that the rendered parserId stays registered?

truph01 · 2026-10-06T10:01:23Z

Reviewer Checklist

I have verified the author checklist is complete (all boxes are checked off).
I verified the correct issue is linked in the ### Fixed Issues section above
I verified testing steps are clear and they cover the changes made in this PR
- I verified the steps for local testing are in the Tests section
- I verified the steps for Staging and/or Production testing are in the QA steps section
- I verified the steps cover any possible failure scenarios (i.e. verify an input displays the correct error message if the entered data is not correct)
- I turned off my network connection and tested it while offline to ensure it matches the expected behavior (i.e. verify the default avatar icon is displayed if app is offline)
I checked that screenshots or videos are included for tests on all platforms
I included screenshots or videos for tests on all platforms
I verified that the composer does not automatically focus or open the keyboard on mobile unless explicitly intended. This includes checking that returning the app from the background does not unexpectedly open the keyboard.
I verified tests pass on all platforms & I tested again on:
- Android: HybridApp
- Android: mWeb Chrome
- iOS: HybridApp
- iOS: mWeb Safari
- MacOS: Chrome / Safari
If there are any errors in the console that are unrelated to this PR, I either fixed them (preferred) or linked to where I reported them in Slack
I verified proper code patterns were followed (see Reviewing the code)
- I verified that any callback methods that were added or modified are named for what the method does and never what callback they handle (i.e. toggleReport and not onIconClick).
- I verified that comments were added to code that is not self explanatory
- I verified that any new or modified comments were clear, correct English, and explained """"why"""" the code was doing something instead of only explaining """"what"""" the code was doing.
- I verified any copy / text that was added to the app is grammatically correct in English. It adheres to proper capitalization guidelines (note: only the first word of header/labels should be capitalized), and is either coming verbatim from figma or has been approved by marketing (in order to get marketing approval, ask the Bug Zero team member to add the Waiting for copy label to the issue)
If a new code pattern is added I verified it was agreed to be used by multiple Expensify engineers
I verified that this PR follows the guidelines as stated in the Review Guidelines
I verified other components that can be impacted by these changes have been tested, and I retested again (i.e. if the PR modifies a shared library or component like Avatar, I verified the components using Avatar have been tested & I retested again)
If a new component is created I verified that:
- A similar component doesn't exist in the codebase
- All props are defined accurately and each prop has a /** comment above it */
- The file is named correctly
- The component has a clear name that is non-ambiguous and the purpose of the component can be inferred from the name alone
- The only data being stored in the state is data necessary for rendering and nothing else
- For Class Components, any internal methods passed to components event handlers are bound to this properly so there are no scoping issues (i.e. for onClick={this.submit} the method this.submit should be bound to this in the constructor)
- Any internal methods bound to this are necessary to be bound (i.e. avoid this.submit = this.submit.bind(this); if this.submit is never passed to a component event handler like onClick)
- All JSX used for rendering exists in the render method
- The component has the minimum amount of code necessary for its purpose, and it is broken down into smaller components in order to separate concerns and functions
If any new file was added I verified that:
- The file has a description of what it does and/or why is needed at the top of the file if the code is not self explanatory
If a new CSS style is added I verified that:
- A similar style doesn't already exist
- The style can't be created with an existing StyleUtils function (i.e. StyleUtils.getBackgroundAndBorderStyle(theme.componentBG)
If the PR modifies code that runs when editing or sending messages, I tested and verified there is no unexpected behavior for all supported markdown - URLs, single line code, code blocks, quotes, headings, bold, strikethrough, and italic.
If the PR modifies a generic component, I tested and verified that those changes do not break usages of that component in the rest of the App (i.e. if a shared library or component like Avatar is modified, I verified that Avatar is working as expected in all cases)
If the PR modifies a component related to any of the existing Storybook stories, I tested and verified all stories for that component are still working as expected.
If the PR modifies a component or page that can be accessed by a direct deeplink, I verified that the code functions as expected when the deeplink is used - from a logged in and logged out account.
If the PR modifies the UI (e.g. new buttons, new UI components, changing the padding/spacing/sizing, moving components, etc) or modifies the form input styles:
- I verified that all the inputs inside a form are aligned with each other.
- I added Design label and/or tagged @Expensify/design so the design team can review the changes.
For any bug fix or new feature in this PR, I verified that sufficient unit tests are included to prevent regressions in this flow.
If the main branch was merged into this PR after a review, I tested again and verified the outcome was still expected according to the Test steps.
I have checked off every checkbox in the PR reviewer checklist, including those that don't apply to this PR.

Screenshots/Videos

Android: HybridApp

Android: mWeb Chrome

iOS: HybridApp

iOS: mWeb Safari

MacOS: Chrome / Safari

The test renders the real MarkdownTextInput under StrictMode inside an <Activity> and records the native parser registry. The parser id the native view renders with stays registered after mount and across a hide and reveal, and an input removed while hidden unregisters it. The pre-patch shape, which registered during render and unregistered in an effect cleanup, fails all three cases.

dariusz-biela · 2026-10-06T10:06:43Z

@truph01
Thanks, I added the test in b243a53 (tests/unit/MarkdownTextInputParserRegistrationTest.tsx). Is this what you had in mind?

truph01 · 2026-10-06T11:26:09Z

@dariusz-biela The tests are failing. Could you check it?

…e-markdown-parser-registration-patch

codecov · 2026-10-06T11:52:14Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
see 31 files with indirect coverage changes

dariusz-biela · 2026-10-06T13:15:22Z

@truph01

All the GitHub Actions are now passing. If you have a moment, I'd appreciate it if you could finish the review.

OSBotify · 2026-10-08T16:38:05Z

✋ This PR was not deployed to staging yet because QA is ongoing. It will be automatically deployed to staging after the next production release.

github-actions · 2026-10-08T16:40:41Z

🚧 roryabraham has triggered a test Expensify/App build. You can view the workflow run here.

github-actions · 2026-10-08T16:58:30Z

🧪🧪 Use the links below to test this adhoc build on Android, iOS, and Web. Happy testing! 🧪🧪
Built from App PR #102415.

Android 🤖	iOS 🍎
https://ad-hoc-expensify-cash.s3.us-east-1.amazonaws.com/rock-artifacts/ad-hoc/rock-android-Adhoc-1fb785b-b8010af-0c05f3ac2cda9b4e145f4da735e872ced7fc0600/index.html	https://ad-hoc-expensify-cash.s3.us-east-1.amazonaws.com/rock-artifacts/ad-hoc/rock-ios-device-AdHoc-1fb785b-b8010af-aefc3ebc5afc33e41539418597f45bb49ca6bc1e/index.html

Web 🕸️
https://102415.pr-testing.expensify.com

👀 View the workflow run that generated this build 👀

OSBotify · 2026-10-08T19:44:34Z

🚀 Deployed to staging by https://github.com/roryabraham in version: 9.5.6-0 🚀

platform	result
🕸 web 🕸	success ✅
🤖 android 🤖	success ✅
🍎 iOS 🍎	success ✅

OSBotify · 2026-10-09T20:30:12Z

🚀 Deployed to production by https://github.com/puneetlath in version: 9.5.6-6 🚀

platform	result
🕸 web 🕸	success ✅
🤖 android 🤖	success ✅
🍎 iOS 🍎	success ✅

Bundle Size Analysis (Sentry):

Android
iOS

dariusz-biela added 2 commits September 18, 2026 15:55

melvin-bot Bot assigned dariusz-biela Sep 28, 2026

docs(patches): link the PR introducing the live-markdown parser patch

887ffa9

dariusz-biela mentioned this pull request Sep 28, 2026

fix(patches): register the live-markdown parser worklet in an insertion effect software-mansion-labs/expensify-app-fork#390

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40 tasks done

dariusz-biela marked this pull request as ready for review September 29, 2026 10:16

dariusz-biela requested a review from a team as a code owner September 29, 2026 10:16

melvin-bot Bot requested review from truph01 and removed request for a team September 29, 2026 10:16

This was referenced Sep 29, 2026

perf(activity): make HomePage lifecycle effects idempotent across hide and reveal software-mansion-labs/expensify-app-fork#418

Draft

perf(navigation): deprioritize covered screens with React Activity instead of react-freeze #98254

Open

dariusz-biela added 2 commits October 6, 2026 13:30

Merge remote-tracking branch 'origin/main' into dariusz-biela/fix/liv…

7a5e1f6

…e-markdown-parser-registration-patch

fix(patches): port the live-markdown parser patch to 0.1.342

7f9da06

truph01 approved these changes Oct 6, 2026

View reviewed changes

melvin-bot Bot requested a review from roryabraham October 6, 2026 15:43

roryabraham approved these changes Oct 8, 2026

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roryabraham merged commit 1fb785b into Expensify:main Oct 8, 2026
40 of 43 checks passed

OSBotify mentioned this pull request Oct 8, 2026

Deploy Checklist: New Expensify 2026-10-08 #103502

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