fix: show a toast when a grade import fails

[Anas12091101]

TL;DR - A successful grade import shows a toast at the bottom of the Gradebook, but a failed one shows nothing there — the error only appears if you click through to the Bulk Management History screen. This adds an error toast so both outcomes are reported where the operator actually pressed Import.

JIRA: n/a

What changed?

• New ImportErrorToast, shown on csvUpload.error, displaying whatever message the API returned rather than wording of its own — so it covers future error types without further frontend work.
• The reducer clears both toasts on csvUpload.started, so one upload is never described by the previous one's result.
• The toast holds for 15s instead of Paragon's 5s default, since the reader has to act on it. Paragon's Toast has no variant prop, so it is styled the same as the success toast and distinguished by its wording.
• Dropped a stray trailing semicolon from the error banner text, and bulkImportError now composes the new bulkImportErrorMessages selector instead of duplicating its join logic.

grade-import-final-narrated.webm

Developer Checklist

• Test suites passing
• Documentation and test plan updated, if applicable
• Received code-owner approving review
• Bumped version number package.json

Testing Instructions

Needs the companion backend PR — openedx/edx-bulk-grades#178 — because on current master a file with nothing to apply is reported as a success, so there is no error for the toast to show.

• Open the Gradebook for a course and click Download Grades.
• Upload that file straight back without editing it. A toast should appear at the bottom saying the import failed and naming the new_override column.
• Click View Bulk Management History on the toast — it should take you to that screen, where the same message appears.
• Now put a number in one new_override column and upload again. You should get the usual success toast, and no error toast.

Reviewer Checklist

Collectively, these should be completed by reviewers of this PR:

• I've done a visual code review
• I've tested the new functionality

FYI: @openedx/content-aurora

[openedx-webhooks]

Thanks for the pull request, @Anas12091101!

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.14%. Comparing base (568914d) to head (abf66bb).

Additional details and impacted files

@@              Coverage Diff               @@
##           legacy-mfe     #615      +/-   ##
==============================================
+ Coverage       95.06%   95.14%   +0.07%     
==============================================
  Files             139      139              
  Lines            1357     1379      +22     
  Branches          266      274       +8     
==============================================
+ Hits             1290     1312      +22     
  Misses             59       59              
  Partials            8        8              

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[Copilot]

🟢 Approval recommended

The failure flow, state transitions, message formatting, navigation, and fallback behavior are coherent and adequately tested.

Pull request overview

Adds failure feedback for grade imports, complementing the companion backend behavior.

Changes:

• Adds a 15-second import-error toast with API details and history navigation.
• Coordinates success/error toast state across upload lifecycle events.
• Refactors error formatting and expands tests.

File summaries

File	Description
src/data/selectors/grades.test.js	Tests error-message formatting.
src/data/selectors/grades.js	Adds reusable error-message selector.
src/data/selectors/app.js	Exposes error-toast state.
src/data/redux/hooks/selectors.js	Adds selector hooks.
src/data/redux/hooks/actions.js	Adds error-toast action hook.
src/data/reducers/app.test.js	Tests toast state transitions.
src/data/reducers/app.js	Manages mutually exclusive toast state.
src/data/actions/app.js	Adds error-toast action.
src/components/GradesView/index.jsx	Mounts the error toast.
src/components/GradesView/ImportErrorToast/messages.js	Defines localized messages.
src/components/GradesView/ImportErrorToast/index.test.jsx	Tests toast rendering.
src/components/GradesView/ImportErrorToast/index.jsx	Implements the toast component.
src/components/GradesView/ImportErrorToast/hooks.test.js	Tests toast behavior and content.
src/components/GradesView/ImportErrorToast/hooks.js	Provides toast data and handlers.

Review details

• Files reviewed: 14/14 changed files
• Comments generated: 0
• Review effort level: Balanced

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[Copilot]

🟢 Approval recommended

The failure and success paths are consistently wired through Redux, safely rendered, and covered by focused tests.

Review details

• Files reviewed: 18/18 changed files
• Comments generated: 0 new
• Review effort level: Balanced

[arbrandes]

With #621, master is now the frontend-base App Repository, and the micro-frontend tree this PR targets lives on the legacy-mfe branch (from which any further Open edX release branches are cut). Please retarget this PR at legacy-mfe; the fix remains relevant to Ulmo and Verawood users.

[Anas12091101]

@arbrandes sorry for the delay, I was on leave.

I have now retargeted this PR at legacy-mfe and rebased onto it.

Could you review this with openedx/edx-bulk-grades#178 when you get a chance?

[arbrandes]

@Anas12091101, the bug also exists in master. Do you mind creating a PR for it? The policy is that we should fix bugs in master before any other branch.