Fix cross-tab sync for collection-root subscribers by elirangoshen · Pull Request #815 · Expensify/react-native-onyx

elirangoshen · 2026-07-28T10:47:20Z

Details

Supersedes #803 (same changes with latest main merged in — re-opened from a branch I can maintain). Originally coming from here, authored by @fabioh8010.

Cross-tab (multi-instance) storage sync events were not delivered to collection-root subscribers — e.g. the LHN subscribing to the whole report_ collection — so actions like pin/unpin, drafting a message, or marking a report read/unread performed in one tab did not sync to other open tabs.

This PR:

Batches storage sync events and notifies collection-root subscribers (not just individual member-key subscribers) when collection members sync from another instance.
Handles legacy pre-batching sync events for backward compatibility.
Splits large sync events into chunks to stay under storage event size limits.

Note: this fix depends on the OnyxDerived recompute coalescing that landed in E/App via Expensify/App#96785 (now on staging). Without coalescing, the extra collection-root notifications caused a derived-value recompute storm. Re-verified against latest E/App main (which includes #96785) — see Manual Tests.

Related Issues

Expensify/App#94839

Linked E/App PR

Expensify/App#97218

Automated Tests

Added tests in tests/unit/onyxTest.ts verifying that both collection-root subscribers (waitForCollectionCallback: true) and collection member subscribers are notified when a collection member syncs from another instance. Existing multi-instance sync tests were updated to the new batched event shape.

Manual Tests

Tested on web against latest E/App main (includes the OnyxDerived microtask coalescing from Expensify/App#96785), with Onyx pinned to this PR's head (latest main merged in, v3.0.94):

Opened two NewDot tabs signed in to the same account.
In Tab A: pinned/unpinned a report, drafted a message in a mid-list report, marked a report read/unread, and sent a message — verified each action synced to Tab B (pin icon, LHN re-ordering, draft icon, unread bold, new message) without refreshing.
Verified no derived recompute storm: instrumented OnyxDerived compute counts in the idle tab — only ~3–6 recomputes per action (previous failure mode without coalescing was thousands of recomputes and a frozen tab).
Verified no console errors and no tab freeze in either tab.

Author Checklist

Screenshots/Videos

Android: Native

Android: mWeb Chrome

iOS: Native

iOS: mWeb Safari

MacOS: Chrome / Safari

Screen.Recording.2026-07-28.at.11.30.11.mov

Screen.Recording.2026-07-28.at.11.31.40.mov

Screen.Recording.2026-07-28.at.11.39.21.mov

…ollections

Collection-root callbacks are now automatic for collection keys, so the option no longer exists on ConnectOptions. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

elirangoshen · 2026-07-28T10:57:23Z

@codex review

chatgpt-codex-connector

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: f4587d6582

ℹ️ About Codex in GitHub

Codex has been enabled to automatically review pull requests in this repo. Reviews are triggered when you

Open a pull request for review
Mark a draft as ready
Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

When you sign up for Codex through ChatGPT, Codex can also answer questions or update the PR, like "@codex address that feedback".

Beamanator · 2026-07-28T15:17:29Z

Eyyy i'm traveling a bit today so won't be able to get to this review till tomorrow, @mountiny looks like you're assigned to the issue Expensify/App#94839, do you want to review today?

truph01 · 2026-07-29T02:15:35Z

@mountiny Could you assign me as a reviewer since I was assigned to Expensify/App#94839?

mountiny · 2026-07-29T17:34:38Z

Happy to review, @situchan can you work on the checklist?

situchan · 2026-07-29T17:35:49Z

@situchan can you work on the checklist?

yes

situchan · 2026-07-29T18:15:23Z

 function raiseStorageSyncManyKeysEvent(onyxKeys: StorageKeyList) {
+    if (onyxKeys.length === 0) {
+        return;
+    }
+
+    let chunk: StorageKeyList = [];
+    let chunkLength = 2; // accounts for the surrounding `[]`
    for (const onyxKey of onyxKeys) {
-        raiseStorageSyncEvent(onyxKey);
+        const keyLength = onyxKey.length + 3; // quotes + comma separator
+        if (chunk.length > 0 && chunkLength + keyLength > MAX_SYNC_PAYLOAD_LENGTH) {
+            emitSyncEvent(JSON.stringify(chunk));
+            chunk = [];
+            chunkLength = 2;
+        }
+        chunk.push(onyxKey);
+        chunkLength += keyLength;
    }
+    if (chunk.length > 0) {
+        emitSyncEvent(JSON.stringify(chunk));


Chunking can split a collection across two events.

Chunks are cut purely by payload size, so if one collection's members land in two different chunks, the receiver sees two storage events → two keysChanged calls → two collection notifications instead of one.
This partially undoes the O(N²)→O(1) win exactly in the large-batch case chunking exists for.
Grouping by collection before chunking would avoid it.

Not blocker though

I think its an edge case , maybe not worth to fix for now.
what do you think @fabioh8010 ?

situchan · 2026-07-29T18:41:26Z

        Onyx.disconnect(connection2);
    });

+    it('should notify collection-root and collection member subscribers when a collection member syncs from another instance', async () => {


A couple of test gaps worth filling.

The two new tests are good, but I'd add:

A deletion test (member removed in another tab → subscribers get undefined). Not only verifying this manually.

A chunking test around the size limit — that logic is currently untested.

Optionally, a test for the legacy raw-key path in parseSyncOnyxStorageEventValue.

I added few tests now.

situchan · 2026-07-29T22:11:38Z

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

test.mov

…y parsing Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

fabioh8010 and others added 4 commits June 29, 2026 11:09

Fix cross-tab sync for collection-root subscribers

e75f5f4

Handle legacy pre-batching storage sync events

05130ea

Split large sync events into chunks

57a1564

Merge remote-tracking branch 'origin/main' into bugfix/tab-sync-for-c…

60c627e

…ollections

melvin-bot Bot assigned elirangoshen Jul 28, 2026

elirangoshen mentioned this pull request Jul 28, 2026

[TESTING ONLY] Pin react-native-onyx to tab-sync-for-collections (Onyx PR #815) Expensify/App#97218

Draft

40 tasks

Drop removed waitForCollectionCallback option from sync tests

f4587d6

Collection-root callbacks are now automatic for collection keys, so the option no longer exists on ConnectOptions. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

elirangoshen marked this pull request as ready for review July 28, 2026 10:57

elirangoshen requested a review from a team as a code owner July 28, 2026 10:57

melvin-bot Bot requested review from Beamanator and removed request for a team July 28, 2026 10:57

elirangoshen mentioned this pull request Jul 28, 2026

[WIP] Fix cross-tab sync for collection-root subscribers #803

Draft

42 tasks

chatgpt-codex-connector Bot reviewed Jul 28, 2026

View reviewed changes

Comment thread lib/storage/InstanceSync/index.web.ts

mountiny self-requested a review July 28, 2026 18:27

elirangoshen marked this pull request as draft July 29, 2026 14:23

elirangoshen force-pushed the eliran/94839-tab-sync-for-collections branch from 4f91425 to f4587d6 Compare July 29, 2026 14:31

mountiny requested a review from situchan July 29, 2026 17:34

situchan reviewed Jul 29, 2026

View reviewed changes

Add tests for member deletion sync, event chunking, and legacy raw-ke…

6c0cf38

…y parsing Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Uh oh!

Fix cross-tab sync for collection-root subscribers - #815

Fix cross-tab sync for collection-root subscribers#815
elirangoshen wants to merge 6 commits into
Expensify:mainfrom
callstack-internal:eliran/94839-tab-sync-for-collections

elirangoshen commented Jul 28, 2026 •

edited

Loading

Uh oh!

elirangoshen commented Jul 28, 2026

Uh oh!

chatgpt-codex-connector Bot left a comment

Uh oh!

Uh oh!

Beamanator commented Jul 28, 2026

Uh oh!

truph01 commented Jul 29, 2026

Uh oh!

mountiny commented Jul 29, 2026

Uh oh!

situchan commented Jul 29, 2026

Uh oh!

situchan Jul 29, 2026

Uh oh!

elirangoshen Jul 30, 2026

Uh oh!

situchan Jul 29, 2026

Uh oh!

elirangoshen Jul 30, 2026

Uh oh!

situchan commented Jul 29, 2026 •

edited

Loading

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

6 participants

Uh oh!

Conversation

elirangoshen commented Jul 28, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Details

Related Issues

Linked E/App PR

Automated Tests

Manual Tests

Author Checklist

Screenshots/Videos

Uh oh!

elirangoshen commented Jul 28, 2026

Uh oh!

chatgpt-codex-connector Bot left a comment

Choose a reason for hiding this comment

💡 Codex Review

Uh oh!

Uh oh!

Beamanator commented Jul 28, 2026

Uh oh!

truph01 commented Jul 29, 2026

Uh oh!

mountiny commented Jul 29, 2026

Uh oh!

situchan commented Jul 29, 2026

Uh oh!

situchan Jul 29, 2026

Choose a reason for hiding this comment

Uh oh!

elirangoshen Jul 30, 2026

Choose a reason for hiding this comment

Uh oh!

situchan Jul 29, 2026

Choose a reason for hiding this comment

Uh oh!

elirangoshen Jul 30, 2026

Choose a reason for hiding this comment

Uh oh!

situchan commented Jul 29, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Reviewer Checklist

Screenshots/Videos

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

6 participants

elirangoshen commented Jul 28, 2026 •

edited

Loading

situchan commented Jul 29, 2026 •

edited

Loading