fix: Copilot plugin - add backfill time window to ensure data consistency

[la-tamas]

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Summary

Add backfill time window to ensure data consistency for GitHub Copilot metrics collection.
GitHub reports are generated hours after midnight, so a midnight run gets 404 for the previous day.
Without a lookback buffer, LatestSuccessStart advances past the missed day permanently.

This change introduces: reportLookbackDays constant: extra days rewound from 'until' on incremental runs dailyMetricsTrailingBackfillDays constant: extends retries for delayed daily report generation\n- clampDailyMetricsStartForBackfill helper to apply the trailing backfill window.

Does this close any open issues?

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Other Information

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[ewega]

Mind fixing conflicts? Hint: if you use copilot you can ask it to fix conflicts for you - https://github.blog/changelog/2026-03-26-ask-copilot-to-resolve-merge-conflicts-on-pull-requests/

[Copilot]

Pull request overview

Adds a lookback/backfill window to the GitHub Copilot metrics collectors so incremental runs retry recently-missed days (e.g., reports not yet generated around midnight), improving data consistency.

Changes:

• Rewinds incremental collection start by a fixed reportLookbackDays and further clamps daily metrics to a trailing backfill window (dailyMetricsTrailingBackfillDays).
• Refactors report metadata parsing/downloading into shared helpers (parseReportMetadataResponse, parseRawReportResponse, parseUserMetricsReportResponse).
• Adds unit tests covering the new date-range/backfill behavior and metadata “empty/204” handling.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
backend/plugins/gh-copilot/tasks/report_download_helper.go	Introduces lookback/backfill constants and shared metadata/record collection helpers.
backend/plugins/gh-copilot/tasks/user_metrics_collector.go	Applies trailing backfill and uses shared user-metrics response parsing.
backend/plugins/gh-copilot/tasks/org_metrics_collector.go	Applies trailing backfill and switches to shared raw-report response parsing.
backend/plugins/gh-copilot/tasks/enterprise_metrics_collector.go	Applies trailing backfill and switches to shared raw-report response parsing.
backend/plugins/gh-copilot/tasks/metrics_collector_test.go	Adds tests for lookback/backfill and metadata parsing edge cases.

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[Copilot]

logReportMetadataParseError logs a snippet of the raw metadata response body. This metadata includes download_links (signed URLs), so on parse errors this can leak sensitive, time-limited URLs into logs. Please redact/remove download_links before logging, or log only non-sensitive fields (e.g., report_day/range and response size/status) instead of the raw body snippet.

Suggested change

	snippet := string(body)
	if len(snippet) > 200 {
	snippet = snippet[:200]
	}
	logger.Error(err, "failed to parse report metadata, body=%s", snippet)
	logger.Error(err, "failed to parse report metadata, body_size=%d bytes", len(body))

[Copilot]

The log message says report day=%s but reportMetadataRange() can return a range like start..end. Please adjust the wording (e.g., report=%s/range=%s) so logs remain accurate for both 1-day and multi-day metadata.

Suggested change

	logger.Info("No download links for report day=%s, skipping", reportRange)
	logger.Info("No download links for report=%s, skipping", reportRange)