fix: acceptance rate now uses suggestion/acceptance count

[Zarthus]

Fix acceptance rate calculation

We are migrating from https://github.com/github-copilot-resources/copilot-metrics-viewer/issues to the Backstage plugin, and noticed one critical difference in our metrics: The "Acceptance Rate Average".

The copilot plugin reports acceptance rate incorrectly, using the lines metrics rather than acceptance/suggestion count. It seems like the same code slightly later down the line does it correctly (minus the rate function):

community-plugins/workspaces/copilot/plugins/copilot/src/components/Cards/DashboardCards.tsx

Lines 52 to 64 in c3bbe0f

	const overallMetrics = {
	acceptanceRate: calculateAcceptanceRate(metrics),
	suggestionsCount:
	metrics.length > 0
	? sumProperty(metrics, 'total_suggestions_count')
	: 'N/A',
	acceptancesCount:
	metrics.length > 0
	? sumProperty(metrics, 'total_acceptances_count')
	: 'N/A',
	linesAccepted:
	metrics.length > 0 ? sumProperty(metrics, 'total_lines_accepted') : 'N/A',
	};

The GitHub API will respond with the following:

[
  {
    "total_suggestions_count": 600,
    "total_acceptances_count": 200,
    "total_lines_suggested": 2500,
    "total_lines_accepted": 500,
    ...

In this case, we expect acceptance rate to be 33%, not 20%, as the Backstage plugin reports. This is because copilot can generate several lines worth of suggestions, and one accept will shoot up (or down) the average significantly, whereas in total_*_count this is just a +1 to the value. Making it more reliable to report as an acceptance rate as it directly is the number of accepts/rejects, and is not influenced by the size of the suggestion.

For reference, here is how copilot-metrics-viewer does it: https://github.com/github-copilot-resources/copilot-metrics-viewer/blob/223cb4fc9f73bd6e7263f8246d9a701aca1983cf/src/components/MetricsViewer.vue#L276-L280

✔️ Checklist

• A changeset describing the change and affected packages. (more info)
• Added or updated documentation
• Tests for new functionality and regression tests for bug fixes
• Screenshots attached (for UI changes)
• All your commits have a Signed-off-by line in the message. (more info)

[backstage-goalie]

Changed Packages

Package Name	Package Path	Changeset Bump	Current Version
@backstage-community/plugin-copilot	workspaces/copilot/plugins/copilot	minor	v0.4.0

[Zarthus]

@nickboldt if you have some time please :)

[BethGriggs]

Should this be a patch? Just curious if intentionally minor

[Zarthus]

I was doubting that myself as well, so visually the change is big - we are suddenly reporting an entirely different number in an existing field and anyone consuming that number should properly communicate that to their user base upon upgrading.

Id be okay with a patch too, i think there's rationales for both sides. (the nature of the bug fix changes the behaviour of an existing feature significantly, which will not be "backwards compatible" visually - but also does not require any change or action from the people depending on the software)