Add Tasks regression coverage for deferred Ink teardown

[dmerand]

WHY are these changes introduced?

Part of https://github.com/shop/issues-develop/issues/22483.

#7062 adds deferred Ink teardown for this task-rendering path.

This follow-up keeps the change narrow and makes that behavior easier to trust by adding focused regression coverage around Tasks, where React can otherwise lose the race to flush the final success or failure state before the tree is unmounted.

WHAT is this pull request doing?

• adds focused Tasks regression coverage for success and failure teardown behavior
• verifies the loading frame is rendered before completion
• verifies the final frame is cleared after success and failure
• does a small cleanup in use-async-and-unmount.ts by centralizing deferred teardown in a helper

How to test your changes?

• Run the Tasks UI tests and confirm the final frame is cleared after success and failure.

Measuring impact

How do we know this change was effective? Please choose one:

• n/a - this doesn't need measurement, e.g. a linting rule or a bug-fix
• Existing analytics will cater for this addition
• PR includes analytics changes to measure impact

Checklist

• I've considered possible cross-platform impacts (Mac, Linux, Windows)
• I've considered possible documentation changes

[dmerand]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• Add Tasks regression coverage for deferred Ink teardown #7118 👈 (View in Graphite)
• Fix progress bars not clearing on completion after React 19 upgrade #7062 : 1 other dependent PR (#7067 )
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.

[github-actions]

Differences in type declarations

We detected differences in the type declarations generated by Typescript for this branch compared to the baseline ('main' branch). Please, review them to ensure they are backward-compatible. Here are some important things to keep in mind:

• Some seemingly private modules might be re-exported through public modules.
• If the branch is behind main you might see odd diffs, rebase main into this branch.

New type declarations

We found no new type declarations in this PR

Existing type declarations

packages/cli-kit/dist/private/node/ui/components/SingleTask.d.ts

@@ -4,8 +4,9 @@ interface SingleTaskProps<T> {
     title: TokenizedString;
     task: (updateStatus: (status: TokenizedString) => void) => Promise<T>;
     onComplete?: (result: T) => void;
+    onError?: (error: Error) => void;
     onAbort?: () => void;
     noColor?: boolean;
 }
-declare const SingleTask: <T>({ task, title, onComplete, onAbort, noColor }: SingleTaskProps<T>) => React.JSX.Element | null;
+declare const SingleTask: <T>({ task, title, onComplete, onError, onAbort, noColor }: SingleTaskProps<T>) => React.JSX.Element | null;
 export { SingleTask };
\ No newline at end of file

[github-actions]

Coverage report

St.❔	Category	Percentage	Covered / Total
🟢	Statements	82.29%	15120/18374
🟡	Branches	74.86%	7457/9961
🟢	Functions	81.31%	3798/4671
🟢	Lines	82.68%	14293/17288

Test suite run success

3993 tests passing in 1527 suites.

Report generated by 🧪jest coverage report action from 35c8ba6

[github-actions]

We detected some changes at packages/*/src and there are no updates in the .changeset.
If the changes are user-facing, run pnpm changeset add to track your changes and include them in the next release CHANGELOG.

Caution

DO NOT create changesets for features which you do not wish to be included in the public changelog of the next CLI release.