Fix: distance expense to new user lands on Workspace with 'previously existing chat' error (new manual expense flow)

[MelvinBot]

Explanation of Change

This fixes a real bug in the new manual expense flow (NEW_MANUAL_EXPENSE_FLOW beta): submitting a Track-distance expense from global-create to a brand‑new user (no existing chat) navigated to a Workspace and showed the backend error "There is a previously existing chat between these users." instead of opening the chat with the new user.

Root cause: On the global‑create Track‑distance flow, the distance navigation auto‑assigns the user's default expense policy and lands on the confirmation page with route.params.reportID set to the Workspace policy‑expense chat. When the user then changes the participant to a brand‑new user via the new‑flow inline participant picker, handleParticipantsAdded re‑binds the transaction's report using firstParticipant?.reportID ?? reportID. A brand‑new user has no existing chat, so firstParticipant?.reportID is undefined and the fallback resolves to the route reportID (the Workspace chat). The submission then carries a participant/report mismatch — the new user as participant but the Workspace as the report — which collides with an existing report and produces the "previously existing chat" error, landing on the Workspace.

Fix: In IOURequestStepConfirmation.tsx, generate a fresh optimistic reportID for a participant that has no existing report instead of falling back to the route (Workspace) reportID. This mirrors the already‑correct participant‑step behavior in useParticipantSubmission.ts:282 (firstParticipantReportID || generateReportID()). The now‑unused reportID dependency was removed from the callback's dependency array.

The change is surgical: it only affects how the report is bound when the user explicitly picks a participant with no existing chat. The self‑DM branch and the default‑participant auto‑assignment are untouched.

Fixed Issues

$ #94289
PROPOSAL: #94289 (comment)

Tests

1. Enable the NEW_MANUAL_EXPENSE_FLOW beta, and use an account that has an auto‑reporting default expense policy (Workspace).
2. Tap the global + (FAB) → Track distance.
3. On the Map tab, set a Start address and a Stop address → Next.
4. On the confirmation page, change the participant to a brand‑new user (an email/domain you have no existing chat with) → Create x.xx expense.
5. Verify you are navigated to the chat with the new user and the expense is created there — not to a Workspace, and no "There is a previously existing chat between these users." error appears.
6. Regression: repeat with an existing user/chat and verify the expense still lands in the correct existing chat.
7. Regression: create a normal manual/distance expense to a Workspace (policy‑expense chat) and verify it still works.
8. Verify that no errors appear in the JS console.

Automated tests run locally by the co-author:

• npm test -- tests/ui/components/IOURequestStepConfirmationPageTest.tsx → 13 passed

• npm test -- tests/ui/components/IOURequestStepDistanceTest.tsx → 1 passed

• npm run typecheck-tsgo, npm run lint-changed, npm run prettier, and react-compiler-compliance-check (no regression) all pass.

• Verify that no errors appear in the JS console

Offline tests

Same as Tests.

QA Steps

1. Enable the NEW_MANUAL_EXPENSE_FLOW beta on a Workspace account with an auto‑reporting default policy.
2. Global + (FAB) → Track distance → Map tab → set Start and Stop addresses → Next.
3. Enter a brand‑new user email (a domain you have no existing chat with) → Create x.xx expense.
4. Verify navigation goes to the chat with the new user and the expense is created there, with no "There is a previously existing chat between these users." error.
5. Regression: repeat for an existing user and for a Workspace, verifying the expense lands in the correct chat.

• 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)
• 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 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 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)
• 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 new assets were added or existing ones were modified, I verified that:
  • The assets are optimized and compressed (for SVG files, run npm run compress-svg)
  • 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)
• 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.
• 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
...es/iou/request/step/IOURequestStepConfirmation.tsx	63.55% <0.00%> (ø)
... and 13 files with indirect coverage changes