[Structural Sharing] PR 1: Centralized key utilities with bidirectional indexes

[fabioh8010]

Details

First PR of Expensify/App#86181

Key-related functions are currently scattered across OnyxUtils and OnyxCache, and collection key lookups require O(C) linear scans over all collection keys. This PR extracts them into a new OnyxKeys module with two pre-computed maps:

• memberToCollectionKeyMap: member key → collection key (O(1) reverse lookup)
• collectionToMembersMap: collection key → Set of member keys (O(1) forward lookup)

Both maps are maintained incrementally as keys are added/removed from cache. The forward lookup is essential for PR 3's snapshot rebuild — it allows iterating only the members of the affected collection instead of scanning all keys. Pure refactor — no behavioral change.

E/App PR: Expensify/App#86201

Related Issues

Expensify/App#86181

Automated Tests

Unit tests were added.

Manual Tests

Since it's 99% refactor there isn't anything specific to test, just assert the app loads and doesn't crash. Use Expensify/App#86201 for testing.

1. Login with an account.
2. Navigate to Inbox tab.
3. Kill the app/refresh page and open app again.
4. Assert it loads correctly.

Author Checklist

• I linked the correct issue in the ### Related Issues section above
• I wrote clear testing steps that cover the changes made in this PR
  • I added steps for local testing in the Tests section
  • I tested this PR with a High Traffic account against the staging or production API to ensure there are no regressions (e.g. long loading states that impact usability).
• I included screenshots or videos for tests on all platforms
• I ran the tests on all platforms & verified they passed on:
  • Android / native
  • Android / Chrome
  • iOS / native
  • iOS / Safari
  • MacOS / Chrome / Safari
• I verified there are no console errors (if there's a console error not related to the PR, report it or open an issue for it to be fixed)
• I followed proper code patterns (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 the left part of a conditional rendering a React component is a boolean and NOT a string, e.g. myBool && <MyComponent />.
  • 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 proper file naming conventions were followed for any new files or renamed files. All non-platform specific files are named after what they export and are not named "index.js". All platform-specific files are named for the platform the code supports as outlined in the README.
  • I verified the JSDocs style guidelines (in STYLE.md) were followed
• If a new code pattern is added I verified it was agreed to be used by multiple Expensify engineers
• I followed the guidelines as stated in the Review Guidelines
• I tested other components that can be impacted by my changes (i.e. if the PR modifies a shared library or component like Avatar, I verified the components using Avatar are working as expected)
• I verified all code is DRY (the PR doesn't include any logic written more than once, with the exception of tests)
• I verified any variables that can be defined as constants (ie. in CONST.js or at the top of the file that uses the constant) are defined as such
• I verified that if a function's arguments changed that all usages have also been updated correctly
• 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
  • If we are not using the full Onyx data that we loaded, I've added the proper selector in order to ensure the component only re-renders when the data it is using changes
  • 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 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 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 author checklist, including those that don't apply to this PR.

Screenshots/Videos

Android: Native

Screen.Recording.2026-03-25.at.08.30.46-compressed.mov

Android: mWeb Chrome

Android Chrome is always crashing for me so I can't test

iOS: Native

Screen.Recording.2026-03-25.at.08.38.48-compressed.mov

iOS: mWeb Safari

Screen.Recording.2026-03-25.at.08.40.05-compressed.mov

MacOS: Chrome / Safari

Screen.Recording.2026-03-25.at.08.41.19-compressed.mov

Screen.Recording.2026-03-25.at.08.43.21-compressed.mov

[fabioh8010]

Ready to review @Julesssss @tgolen

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Resolve member keys to the most specific collection prefix

registerMemberKey() assigns the collection by taking the first startsWith() match from collectionKeySet, which is order-dependent and incorrect for valid overlapping collection keys (for example, test_ and test_level_). In that case, registering test_level_1 can be cached under test_; because getCollectionKey() returns cached mappings first, later collection routing (callbacks, grouping, RAM-only checks) uses the wrong parent collection. This matching logic should prefer the longest compatible collection key, not the first iterated one.

Useful? React with 👍 / 👎.

[fabioh8010]

Makes sense, addressed on 1351565

[chatgpt-codex-connector]

Clear stale member indexes when collection keys are reset

setCollectionKeys() only replaces collectionKeySet and leaves memberToCollectionKeyMap/collectionToMembersMap intact. If Onyx.init() runs again with a different key schema, old member mappings remain in the fast path and getCollectionKey() can return collection keys that are no longer registered, causing misclassification of subsequent updates. Reinitializing or rebuilding both indexes when setting new collection keys is needed to avoid stale lookups.

Useful? React with 👍 / 👎.

[fabioh8010]

Onyx.init() should never be called again in the same session so we're safe.

[tgolen]

How about simplifying this a little?

return ramOnlyKeySet.has(key) || ramOnlyKeySet.has(getCollectionKey(key));

This also utilizes an early return for the simple key lookups without having to go through all the getCollectionKey() logic for every single key.

[tgolen]

It would be nice to have a little comment for each of these to explain why the returned value is "correct".