Fold "Close Stale PRs" into a deterministic pr-triage stale sweep

.github/scripts/pr-stale-sweep.sh

@@ -0,0 +1,210 @@
+#!/usr/bin/env bash
+# pr-stale-sweep.sh
+#
+# Deterministic stale-PR sweep. Replaces the former agentic
+# `close-stale-prs.agent.md`: no model calls, no tokens — just the GitHub API.
+#
+# Policy (unchanged from the agentic version):
+#   * Consider every OPEN pull request, including drafts.
+#   * "Last activity" is the most recent NON-bot comment or review; if there is
+#     none, it falls back to the PR's created_at. We deliberately ignore
+#     `updated_at` and all `[bot]` activity so the bot's own stale-warning
+#     comment never resets the inactivity timer.
+#   * created <= 30 days ago                          -> skip (too new)
+#   * 30 days < inactivity <= 37 days                 -> post a stale WARNING
+#                                                        (once; marker-guarded)
+#   * inactivity > 37 days                            -> CLOSE the PR
+#   * label `no-stale`                                -> exempt (skip)
+#   * author dotnet-maestro[bot] / dotnet-maestro     -> exempt (skip)
+#
+# Required env:
+#   GH_TOKEN            — token with pull-requests:write, issues:write
+#   GITHUB_REPOSITORY   — owner/repo (set by Actions)
+#
+# Optional env:
+#   DRY_RUN     — "true" to log intended actions without any writes
+#   STALE_MAX   — hard cap on warn+close writes per run (default 25)
+#   WARN_DAYS   — inactivity threshold for a warning (default 30)
+#   CLOSE_DAYS  — inactivity threshold for a close   (default 37)
+#
+# Exits 0 on success (including no-op). Non-zero only on hard failures.
+
+set -euo pipefail
+
+: "${GH_TOKEN:?GH_TOKEN is required}"
+: "${GITHUB_REPOSITORY:?GITHUB_REPOSITORY is required}"
+
+DRY_RUN="${DRY_RUN:-false}"
+STALE_MAX="${STALE_MAX:-25}"
+WARN_DAYS="${WARN_DAYS:-30}"
+CLOSE_DAYS="${CLOSE_DAYS:-37}"
+
+REPO="$GITHUB_REPOSITORY"
+OWNER="${REPO%/*}"
+NAME="${REPO#*/}"
+
+# Idempotency marker embedded in every warning comment. Its presence on a PR
+# means "already warned" regardless of how the visible text may change.
+WARN_MARKER="<!-- pr-triage:stale-warning -->"
+
+NOW_SECS=$(date -u +%s)
+WARN_CUTOFF_SECS=$(( WARN_DAYS * 86400 ))
+CLOSE_CUTOFF_SECS=$(( CLOSE_DAYS * 86400 ))
+
+log() { printf '[stale-sweep] %s\n' "$*" >&2; }
+summary() {
+  if [ -n "${GITHUB_STEP_SUMMARY:-}" ]; then
+    printf '%s\n' "$*" >> "$GITHUB_STEP_SUMMARY"
+  fi
+}
+
+# Parse an ISO-8601 timestamp to epoch seconds (GNU date on the runner; BSD fallback).
+to_epoch() {
+  local ts="$1"
+  date -u -d "$ts" +%s 2>/dev/null || date -u -j -f "%Y-%m-%dT%H:%M:%SZ" "$ts" +%s
+}
+
+WARNING_BODY() {
+  cat <<EOF
+$WARN_MARKER
+This PR has been automatically marked as stale because it has no activity for ${WARN_DAYS} days. It will be closed if no further activity occurs within another $(( CLOSE_DAYS - WARN_DAYS )) days of this comment. If it is closed, you may reopen it anytime when you're ready again.
+EOF
+}
+
+CLOSING_BODY() {
+  cat <<EOF
+This pull request has been automatically closed because it has been open for more than ${WARN_DAYS} days with no recent activity.
+
+If you believe this work is still relevant, please feel free to reopen or create a new pull request. Thank you for your contribution!
+EOF
+}
+
+# Most recent NON-bot activity epoch for a PR. Considers issue comments and
+# reviews; ignores any author whose login ends in "[bot]". Falls back to the
+# supplied created_at epoch when there is no human activity.
+last_non_bot_activity_epoch() {
+  local pr="$1" created_epoch="$2"
+  local newest_ts
+
+  # Emit one timestamp per non-bot comment/review, then pick the max. --paginate
+  # runs --jq per page, so we must aggregate in the shell, not inside jq.
+  newest_ts=$(
+    {
+      gh api --paginate "repos/$REPO/issues/$pr/comments" \
+        --jq '.[] | select((.user.login | endswith("[bot]")) | not) | .created_at' 2>/dev/null || true
+      gh api --paginate "repos/$REPO/pulls/$pr/reviews" \
+        --jq '.[] | select(.user != null) | select((.user.login | endswith("[bot]")) | not) | .submitted_at' 2>/dev/null || true
+    } | grep -v '^null$' | sort | tail -n 1
+  )
+
+  if [ -z "$newest_ts" ]; then
+    echo "$created_epoch"
+    return
+  fi
+  to_epoch "$newest_ts"
+}
+
+already_warned() {
+  local pr="$1" hit
+  hit=$(gh api --paginate "repos/$REPO/issues/$pr/comments" \
+    --jq ".[] | select(.body | contains(\"$WARN_MARKER\")) | .id" 2>/dev/null | head -n 1)
+  [ -n "$hit" ]
+}
+
+log "repo=$REPO dry_run=$DRY_RUN warn>${WARN_DAYS}d close>${CLOSE_DAYS}d max=$STALE_MAX"
+
+summary "## Stale PR sweep"
+summary ""
+summary "Repo \`$REPO\` · dry_run=\`$DRY_RUN\` · warn>\`${WARN_DAYS}d\` · close>\`${CLOSE_DAYS}d\` · max=\`$STALE_MAX\`"
+summary ""
+summary "| PR | author | created | inactivity(d) | decision |"
+summary "|---:|---|---|---:|---|"
+
+# Enumerate all open PRs (drafts included). --limit caps the working set; PRs
+# newer than WARN_DAYS are filtered out per-PR below.
+PRS_JSON=$(gh pr list --repo "$REPO" --state open --limit 500 \
+  --json number,createdAt,isDraft,author,labels)
+
+COUNT=$(jq 'length' <<<"$PRS_JSON")
+log "open PRs fetched: $COUNT"
+
+ACTIONS=0
+processed=0
+while IFS= read -r row; do
+  PR=$(jq -r '.number' <<<"$row")
+  CREATED_AT=$(jq -r '.createdAt' <<<"$row")
+  AUTHOR=$(jq -r '.author.login // ""' <<<"$row")
+  LABELS=$(jq -r '[.labels[].name] | join(",")' <<<"$row")
+
+  # Exemptions ------------------------------------------------------------
+  if [[ ",$LABELS," == *",no-stale,"* ]]; then
+    log "PR #$PR: no-stale label — exempt"
+    continue
+  fi
+  case "$AUTHOR" in
+    "dotnet-maestro[bot]"|"dotnet-maestro")
+      log "PR #$PR: maestro-authored — exempt"
+      continue ;;
+  esac
+
+  CREATED_EPOCH=$(to_epoch "$CREATED_AT")
+  AGE_SECS=$(( NOW_SECS - CREATED_EPOCH ))
+  # Too new: opened within WARN_DAYS.
+  if [ "$AGE_SECS" -le "$WARN_CUTOFF_SECS" ]; then
+    continue
+  fi
+
+  LAST_EPOCH=$(last_non_bot_activity_epoch "$PR" "$CREATED_EPOCH")
+  INACTIVE_SECS=$(( NOW_SECS - LAST_EPOCH ))
+  INACTIVE_DAYS=$(( INACTIVE_SECS / 86400 ))
+
+  DECISION="skip(active)"
+  if [ "$INACTIVE_SECS" -gt "$CLOSE_CUTOFF_SECS" ]; then
+    DECISION="close"
+  elif [ "$INACTIVE_SECS" -gt "$WARN_CUTOFF_SECS" ]; then
+    if already_warned "$PR"; then
+      DECISION="skip(already-warned)"
+    else
+      DECISION="warn"
+    fi
+  fi
+
+  if [ "$DECISION" = "skip(active)" ] || [ "$DECISION" = "skip(already-warned)" ]; then
+    log "PR #$PR: inactivity=${INACTIVE_DAYS}d -> $DECISION"
+    continue
+  fi
+
+  summary "| #$PR | $AUTHOR | ${CREATED_AT%%T*} | $INACTIVE_DAYS | $DECISION |"
+
+  if [ "$ACTIONS" -ge "$STALE_MAX" ]; then
+    log "PR #$PR: reached STALE_MAX=$STALE_MAX — skipping remaining writes"
+    continue
+  fi
+
+  case "$DECISION" in
+    close)
+      if [ "$DRY_RUN" = "true" ]; then
+        log "PR #$PR: [DRY_RUN] would close (inactivity=${INACTIVE_DAYS}d)"
+      else
+        gh pr comment "$PR" --repo "$REPO" --body "$(CLOSING_BODY)" >/dev/null
+        gh pr close "$PR" --repo "$REPO" >/dev/null
+        log "PR #$PR: closed (inactivity=${INACTIVE_DAYS}d)"
+      fi
+      ACTIONS=$(( ACTIONS + 1 ))
+      ;;
+    warn)
+      if [ "$DRY_RUN" = "true" ]; then
+        log "PR #$PR: [DRY_RUN] would post stale warning (inactivity=${INACTIVE_DAYS}d)"
+      else
+        gh pr comment "$PR" --repo "$REPO" --body "$(WARNING_BODY)" >/dev/null
+        log "PR #$PR: warned (inactivity=${INACTIVE_DAYS}d)"
+      fi
+      ACTIONS=$(( ACTIONS + 1 ))
+      ;;
+  esac
+  processed=$(( processed + 1 ))
+done < <(jq -c '.[]' <<<"$PRS_JSON")
+
+summary ""
+summary "**Actions taken (warn+close): $ACTIONS** (dry_run=\`$DRY_RUN\`)"
+log "done — actions=$ACTIONS"