fix: Discard changes modal does't show up when going back with the browser back button

[TaduJR]

Explanation of Change

Browser back never showed the "Discard changes" confirmation. The back navigation arrives as a root-targeted RESET that keeps all route keys and only changes nested state, and shouldPreventRemove only inspects removed keys — so usePreventRemove/beforeRemove never fired react-navigation/react-navigation#9031.

The bug has two variants, each fixed before the navigation state commits:

• Nested removal (Merchant, Description, Avatar): patched @react-navigation/core to propagate the beforeRemove check into nested navigators on a key-preserving RESET.

• Focus-only change (tab switches — nothing is removed, so beforeRemove can't fire by design): on web, a new DiscardChangesGuard vetoes a RESET that would unfocus a registered dirty screen, skipping the guard framework's replaceState history sync (it would desync createMemoryHistory) in favor of a history.go(1) URL restore. On Android, the same switch arrives as a TabRouter GO_BACK, intercepted with a BackHandler in the native hook — a router-level guard isn't possible because canGoBack() probes call getStateForAction speculatively.

Also:

• addRootHistoryRouterExtension now passes same-reference (blocked/no-op) router results through untouched; rehydrating them leaked a state event that rewrote the back-target history entry.
• Each tab-host start page registers a flow-level check for draft-persisted input (e.g. Map waypoints), covering future draft-backed tabs automatically; screens with local input (Odometer, Manual distance, Amount, Time) register their own.

Fixed Issues

$ #84246
PROPOSAL: #84246 (comment)

Tests

Scope: This PR covers the back button only (browser back, the phone back button, and the iOS edge-swipe). Clicking between tabs is handled by a separate PR (#89612) and is out of scope here — clicking a tab that has unsaved data is not expected to show a warning in this build, so do not raise that as a bug against this PR.

Setup: Sign in to an account with a workspace that has time tracking turned on and Receipt partners (Uber) turned on (admin access). Have one distance expense created from the Map and one ordinary expense already in a chat.

Scenario 1 — Create expense

1. Tap the green + button → tap Create expense.
2. Switch once to a tab other than the one it opened on.
3. Press the browser back button.
4. Verify: the whole Create expense screen closes and you return to the chat list. You are not dropped onto a previous tab, and the page is not blank or frozen.
5. Open Create expense again, switch to a different tab, then refresh the page.
6. Verify: it reopens on the same tab you were on.

Scenario 2 — Track distance

1. Tap + → tap Track distance.
2. Switch once to a tab other than the one it opened on (Map / Manual / GPS / Odometer).
3. Press the browser back button.
4. Verify: the whole Track distance screen closes and you return to the chat list. You are not dropped onto a previous tab, and the page is not blank or frozen.
5. Open Track distance again, switch to a different tab, then refresh the page.
6. Verify: it reopens on the same tab.

Scenario 3 — Edit distance

1. Open the distance expense → tap the Distance row.
2. Switch from the Map tab to the Manual tab.
3. Press the browser back button.
4. Verify: the whole screen closes and you return to the expense details. You are not dropped onto a previous tab, and the page is not blank or frozen.
5. Reopen it, switch tab, then refresh the page.
6. Verify: it reopens on the same tab.

Scenario 4 — Split expense

1. Open an expense → tap the ⋯ menu in the header → tap Split. (If tabs do not appear, the expense is already split — skip this scenario.)
2. Switch once to a tab other than the one it opened on (Amount / Percent / Date).
3. Press the browser back button.
4. Verify: the whole screen closes and you return to the expense. You are not dropped onto a previous tab, and the page is not blank or frozen.
5. Reopen it, switch tab, then refresh the page.
6. Verify: it reopens on the same tab.

Scenario 5 — Start chat

1. Tap + → tap Start chat.
2. Switch from the Chat tab to the Room tab.
3. Press the browser back button.
4. Verify: the whole screen closes and you return to the chat list. You are not dropped onto a previous tab, and the page is not blank or frozen.
5. Reopen it, switch tab, then refresh the page.
6. Verify: it reopens on the same tab.

Scenario 6 — Receipt partner invites

1. Go to Workspace settings → Receipt partners → Uber → Manage invites.
2. Switch once to a tab other than the one it opened on (All / Linked / Outstanding).
3. Press the browser back button.
4. Verify: the whole screen closes and you return to the Receipt partners page. You are not dropped onto a previous tab, and the page is not blank or frozen.
5. Reopen it, switch tab, then refresh the page.
6. Verify: it reopens on the same tab.

Scenario 7 — Share to Expensify (mobile web only)

1. From another app, use the OS Share sheet → tap Share to Expensify.
2. Switch between the Share and Submit tabs (Submit only appears when the shared file is a receipt).
3. Press the browser back button.
4. Verify: the share screen closes. You are not dropped onto a previous tab, and the page is not blank or frozen.

Scenario 8 — Entering data still warns before leaving (Track distance)

1. Open Track distance → Map tab. Drop a Start and a Finish waypoint.
2. Press the browser back button.
3. Verify: a “Discard changes?” dialog appears.
4. Tap Cancel.
5. Verify: you stay on the Map tab and your waypoints are still there.
6. Press browser back again → tap Discard.
7. Verify: the whole Track distance screen closes.
8. Repeat steps 1–7 starting fresh on the Manual tab (type a distance) and on the Odometer tab (enter readings).

Scenario 9 — Entering data still warns before leaving (Time)

1. Open Create expense → Time tab. Type a number of hours.
2. Press the browser back button.
3. Verify: a “Discard changes?” dialog appears.
4. Tap Cancel and confirm your hours are still there.
5. Press browser back again → tap Discard.
6. Verify: the whole screen closes.

• Verify that no errors appear in the JS console

Offline tests

Same as tests

QA Steps

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

• [ x] 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
  • MacOS: Desktop
• 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 verified there are no new alerts related to the canBeMissing param for useOnyx
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    • 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)
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  • The assets are optimized and compressed (for SVG files, run npm run compress-svg)
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• 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.
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  • I verified that all the inputs inside a form are aligned with each other.
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• 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-Native.mp4

Android: mWeb Chrome

Android-mWeb.mp4

iOS: Native

iOS: mWeb Safari

iOS-Safari.mp4

MacOS: Chrome / Safari

Mac-Chrome.mp4

[melvin-bot]

@bernhardoj 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]

[github-actions]

⚠️ 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. ⚠️

[TaduJR]

cc @ShridharGoel

[codecov]

Codecov Report

❌ Looks like you've decreased code coverage for some files. Please write tests to increase, or at least maintain, the existing level of code coverage. See our documentation here for how to interpret this table.

Files with missing lines	Coverage Δ
...ooks/useDiscardChangesConfirmation/index.native.ts	100.00% <100.00%> (+100.00%)	⬆️
src/hooks/useDiscardChangesConfirmation/index.ts	95.55% <100.00%> (+95.55%)	⬆️
src/libs/Navigation/OnyxTabNavigator.tsx	75.00% <ø> (ø)
...rc/libs/Navigation/OnyxTabNavigatorConfig/index.ts	100.00% <100.00%> (ø)
src/libs/TransactionUtils/index.ts	88.65% <100.00%> (+0.01%)	⬆️
...ibs/Navigation/OnyxTabNavigatorConfig/index.web.ts	0.00% <0.00%> (ø)
.../pages/iou/request/step/IOURequestStepDistance.tsx	76.47% <50.00%> (-0.25%)	⬇️
src/pages/iou/MoneyRequestAmountForm.tsx	83.90% <33.33%> (-1.81%)	⬇️
...ges/iou/request/step/IOURequestStepDistanceMap.tsx	0.00% <0.00%> (ø)
...ges/settings/Agents/Fields/EditAgentAvatarPage.tsx	0.00% <0.00%> (ø)
... and 4 more
... and 15 files with indirect coverage changes

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platform	result
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Deploy Blocker #94844 was identified to be related to this PR.

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Deploy Blocker #94845 was identified to be related to this PR.

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Deploy Blocker #94861 was identified to be related to this PR.

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This PR failing because of the issue #94863
This issue is reproducible in: Android app

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