[$250] [Explain feature] Add support for the "Explain" button in the front end

[marcaaron]

Part of the "Explain Concierge AI actions" project

Main issue: https://github.com/Expensify/Expensify/issues/567869

Feature Description

• For this feature we need to implement an "Explain" button in the frontend for any report action that has a reasoning field.
• This button will exist in the right-click menu for now
• To start it will be visible on the following report actions:
  • Concierge auto-categorized something using AI
  • Concierge auto-submitted a report
• Not shown in mockup: When the user taps explain we will create a comment thread off of the system message
• There should be a comment from the user's perspective that says: "Please explain this to me."
• Concierge should then respond with reason.

BE Changes are in development now.

Upwork Automation - Do Not Edit

• Upwork Job URL: https://www.upwork.com/jobs/~022004286620315057042
• Upwork Job ID: 2004286620315057042
• Last Price Increase: 2025-12-25
• Automatic offers:
• samranahm | Contributor | 109921480

Issue Owner

Current Issue Owner: @eh2077

[melvin-bot]

Job added to Upwork: https://www.upwork.com/jobs/~022004286620315057042

[melvin-bot]

Triggered auto assignment to Contributor-plus team member for initial proposal review - @eh2077 (External)

[melvin-bot]

Auto-assign attempt failed, all eligible assignees are OOO.