extract useParticipantSubmission hook

[OlimpiaZurek]

Explanation of Change

Part of the ongoing IOURequestStepConfirmation decomposition, aimed at improving the create expense flow performance.

Extracts submission logic from IOURequestStepParticipants into a useParticipantSubmission hook, and fixes all React Compiler violations so the hook is fully memoized.

What was extracted

IOURequestStepParticipants was 491 lines. The bulk of it was submission callbacks (trackExpense, addParticipant, goToNextStep) that each maintained their own Onyx subscriptions inline, along with a waitForKeyboardDismiss helper and a dataRef pattern to keep callback identities stable. The component now sits at 160 lines — route params, header title derivation, and JSX.

The new useParticipantSubmission hook owns all of this: Onyx subscriptions, the dataRef pattern, and the three callbacks. It returns only {addParticipant, goToNextStep}.

Fixed Issues

$ #87959
PROPOSAL:

Tests

1. Open create expense flow, select Manual, enter an amount, verify Participants step loads, select a workspace or person and verify Confirmation step opens
2. Open create expense flow, select Scan, attach a receipt, verify Participants step loads and verify Confirmation step opens
3. Open create expense flow, select Distance, enter a distance, verify Participants step loads, select a workspace and verify Confirmation step opens
4. Open split expense flow, verify participants are pre-filled, add more participants and verify Confirmation step opens
5. Open create expense flow, on the Participants step select self-DM and verify it routes to Track Expense confirmation
6. Open invoice flow, select an invoice room and verify Confirmation step opens
7. Open Categorize from Search, verify Participants step clears on focus, select a workspace and verify it navigates to the correct next step. Repeat for Share action
8. On Android select a participant on the Participants step and verify keyboard fully hides before navigating to Confirmation step
9. On iPhone Safari repeat step 8 and verify keyboard fully hides before navigating to Confirmation step

• Verify that no errors appear in the JS console

Offline tests

QA Steps

same as tests
// TODO: These must be filled out, or the issue title must include "[No QA]."

• Verify that no errors appear in the JS console

PR Author Checklist

• I linked the correct issue in the ### Fixed 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 added steps for the expected offline behavior in the Offline steps section
  • I added steps for Staging and/or Production testing in the QA steps section
  • I added steps to cover 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 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: mWeb Chrome
  • iOS: Native
  • iOS: mWeb 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)
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  • I verified any copy / text shown in the product is localized by adding it to src/languages/* files and using the translation method
    • If any non-english text was added/modified, I used JaimeGPT to get English > Spanish translation. I then posted it in #expensify-open-source and it was approved by an internal Expensify engineer. Link to Slack message:
  • I verified all numbers, amounts, dates and phone numbers shown in the product are using the localization methods
  • 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)
  • 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.
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• I verified that if a function's arguments changed that all usages have also been updated correctly
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  • 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
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  • A similar style doesn't already exist
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  • The assets load correctly across all supported platforms.
• 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)
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• 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.
• If a new page is added, I verified it's using the ScrollView component to make it scrollable when more elements are added to the page.
• I added unit tests for any new feature or bug fix in this PR to help automatically prevent regressions in this user 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.

Screenshots/Videos

Android: Native

Android: mWeb Chrome

iOS: Native

iOS: mWeb Safari

MacOS: Chrome / Safari

[codecov]

Codecov Report

✅ Changes either increased or maintained existing code coverage, great job!

Files with missing lines	Coverage Δ
src/utils/keyboard/index.website.ts	0.00% <0.00%> (ø)
...es/iou/request/step/IOURequestStepParticipants.tsx	0.00% <0.00%> (ø)
src/hooks/useParticipantSubmission.ts	0.00% <0.00%> (ø)
... and 12 files with indirect coverage changes

[melvin-bot]

@marcaaron 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]

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Memoize transaction IDs before subscribing to Onyx

transactionIDs is recomputed as a new array on every render and then fed into useTransactionsByID, whose selector is memoized on the transactionIDs reference; this makes the selector dependency change each render and triggers unnecessary resubscribe/reselect churn during participant-step interactions (e.g., typing/search updates). The previous implementation intentionally memoized IDs to avoid this hot-path overhead, so this regression can hurt the performance this refactor is trying to improve.

Useful? React with 👍 / 👎.

[OlimpiaZurek]

The useOptimisticDraftTransactions hook is compiled by React Compiler, so draftTransactions only gets a new reference on actual Onyx writes to COLLECTION.TRANSACTION_DRAFT . useTransactionsByID is also compiled with transactionsSelector cached on transactionIDs. On the participants step, the hot path is search (updates RAM_ONLY_IS_SEARCHING_FOR_REPORTS, not COLLECTION.TRANSACTION_DRAFT), so transactionIDs stays stable during search