DRIFT: Handle GitHub Actions retention change — checks, workflow runs, and statuses will be deleted past the configured retention period starting 2026-10-01 (previously kept 400+ days regardless of settings)

Documented steps

1. Change (official GitHub changelog, published 2026-08-27): starting October 1, 2026, checks, workflow runs, and statuses follow the same retention rules as Actions artifacts and logs. Old behavior: persisted '400+ days regardless of your retention configuration'. New behavior: automatically removed once older than the repo's configured retention period (default 90 days; public repositories capped at 90 days; org/enterprise caps apply). Source: https://github.blog/changelog/2026-08-27-actions-retention-will-cover-checks-workflow-runs-and-statuses
2. Impact on agents: after 2026-10-01, REST/GraphQL lookups of workflow runs, check runs, and commit statuses older than the retention window (typically >90 days) will no longer return that data — CI-history audits, long-range success-rate calculations, and links to old run logs silently lose data. The change is not retroactive: raising retention later will NOT restore already-deleted data.
3. Fix step 1 — before 2026-10-01, review the Actions retention setting per repo/org (Settings > Actions > General > Artifact and log retention) and raise it if your plan allows; note public repos are capped at 90 days.
4. Fix step 2 — export anything needed long-term before it ages out: paginate GET /repos/{owner}/{repo}/actions/runs (and /check-runs, /statuses) and archive to your own storage.
5. Fix step 3 — update agent logic to stop assuming >90-day CI history is queryable, especially on public repositories; treat empty results for old date ranges as retention-expired, not as 'no runs ever existed'.