Fix unread marker disappears after revealing Concierge history in side panel

[collectioneur]

Explanation of Change

Fixes the "New" unread marker disappearing when Concierge hidden history is revealed via "Show history". useUnreadMarker now only advances the read watermark when the newest visible action actually advances (a bulk history reveal no longer pushes it past unread messages), ignores the synthetic Concierge greeting as a push target, and a new newMessageBoundaryTime param prevents revealed history actions from being treated as read-on-arrival.

Fixed Issues

$ #100006

Tests

1. Send a message to Concierge so the chat has a few messages.
2. Long-press (or right-click) one of the earlier Concierge messages and mark it as unread.
3. Navigate to any other chat.
4. Open the Concierge chat in the side panel.
5. Click "Show history".
6. Verify that the green "New" unread marker appears right above the message you marked as unread.

• Verify that no errors appear in the JS console

Offline tests

1. Mark an earlier Concierge message as unread while online, then go offline.
2. Open another chat, open Concierge in the side panel, and click "Show history".
3. Verify that the "New" unread marker appears above the marked message and remains stable while offline.

QA Steps

Same as tests.

• 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)
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  • 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.
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• 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 a new CSS style is added I verified that:
  • A similar style doesn't already exist
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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.
• 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.
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• 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

Screen.Recording.2026-09-02.at.12.09.15.mov

[collectioneur]

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[chatgpt-codex-connector]

Pass the side-panel session timestamp

When Concierge is opened only in the side panel, this reads the main-DM ConciergeSessionContext, whose timestamp remains null because useStartConciergeSession starts it only for isConciergeMainDM. Meanwhile, useReportActionsVisibility lines 69–75 filters side-panel history using SidePanelStateContext.sessionStartTime. Consequently, the exact cold side-panel “Show history” flow passes no boundary here, so the newly revealed unread action is treated as a just-arrived action and the marker is suppressed on the reveal render. Select the same side-panel/main-DM timestamp used by the visibility hook.

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