agent-orchestrator/.changeset/scm-github-pr-cache.md

@aoagents/ao-plugin-scm-github
patch

scm-github: cache 5 gh pr view callsites with per-method TTLs

The lifecycle worker repeatedly polls each PR for state, summary, reviews,
and review decision. Trace data showed gh pr view was the single largest
AO-side endpoint at 1,280 calls per 5-session tier-5 run with >97% duplicate
rate (e.g. PR #184 polled 86× for --json state alone in 11.5 minutes).

Adds an in-process per-instance cache inside createGitHubSCM(), keyed by
${owner}/${repo}#${prKey}:${method} so different field-sets stay isolated.
Per-method TTLs balance reduction against staleness on decision-influencing
fields:

• resolvePR: 60s (identity metadata only — number, url, title, branch refs, isDraft)
• getPRState: 5s
• getPRSummary: 5s
• getReviews: 5s
• getReviewDecision: 5s

assignPRToCurrentUser, mergePR, and closePR each invalidate the entire
PR cache for that PR after the mutation, so AO never sees stale state from
its own writes. Failures are not cached.

getCIChecksFromStatusRollup and getMergeability are intentionally NOT
cached here — those need ETag-based revalidation, not blind TTL, and will
land in a follow-up change.

Expected reduction: ~1,165 of ~1,280 gh pr view calls per tier-5 run.

Tests: 73 existing + 12 new cache tests, all passing.