#!/usr/bin/env bash
# shellcheck disable=SC2016 # backticks in comment bodies are Markdown literals
if [ "${BASH_SOURCE[0]}" = "$0" ]; then
  set -euo pipefail
else
  set -u
fi

# The issue-flow half of the labels state machine. Decisions are pure strings;
# API calls live below the divider so fixture tests can exercise every branch.

ISSUEFLOW_NOW="${ISSUEFLOW_NOW:-$(date -u +%s)}"
ISSUEFLOW_STALE_HOURS="${ISSUEFLOW_STALE_HOURS:-48}"
[[ "$ISSUEFLOW_NOW" =~ ^[0-9]+$ ]] || {
  echo "issueflow: ISSUEFLOW_NOW must be UTC epoch seconds" >&2
  if [ "${BASH_SOURCE[0]}" = "$0" ]; then exit 1; else return 1; fi
}
[[ "$ISSUEFLOW_STALE_HOURS" =~ ^[0-9]+$ ]] || {
  echo "issueflow: ISSUEFLOW_STALE_HOURS must be a non-negative integer" >&2
  if [ "${BASH_SOURCE[0]}" = "$0" ]; then exit 1; else return 1; fi
}
NOW="$ISSUEFLOW_NOW"
STALE_AFTER=$((ISSUEFLOW_STALE_HOURS * 3600))
QUEUE_LABELS=(ready claimed blocked post-merge)
TRIAGE_ACTORS=()

# The needs-ruling invariants (#52) — one implementation for both surfaces.
# shellcheck source=lib/ruling.sh
. "$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)/../../lib/ruling.sh"
# The attention target invariants (#232) — diagnosis only, both surfaces.
# shellcheck source=lib/attention.sh
. "$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)/../../lib/attention.sh"
# The guarded read and its reason line (#101, #247) — one implementation for
# both surfaces.
# shellcheck source=lib/read.sh
. "$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)/../../lib/read.sh"

# The status a per-issue subshell exits with when it walked away from an
# unreadable fact (#247 D4). Distinguished from every other non-zero status so
# a deliberate skip is counted rather than reported as a crash — and so the
# existing crash handler still names a genuine one.
ISSUEFLOW_SKIP=3
# Set by reconcile_issue_pass, read once by main for the D6 tail.
SKIPPED_COUNT=0
SKIPPED_ISSUES=""

# A per-issue pass is ATOMIC: it commits its whole effect or none of it
# (#247 D1). Inside reconcile_issue_pass's subshell, `run` and `log` do not
# act — they append here, and commit_staged_effects replays them in order
# once the pass has completed. Everywhere else (the arrival path, the sweep's
# own lines) they act immediately, as they always did.
#
# This is the ordering invariant itself, not a fix for the two sites that
# happened to violate it: a mutation reached before a later guarded read is
# what let a pass remove `stale`, or mint `needs-triage`, and THEN report the
# issue as skipped — the sweep saying it touched nothing while a write had
# landed, which is the same false-report class #247 exists to close. Stated
# per site it would hold until the next composition; stated here it holds for
# compositions nobody has written yet, because reconcile_issue has no way to
# mutate directly.
#
# Reads are deliberately NOT staged. They may happen anywhere in the pass,
# because nothing lands until the end.
STAGING=false
STAGED_EFFECTS=()

emit() { printf 'issueflow: %s\n' "$*"; }
apply() { if [ -n "${DRY_RUN:-}" ]; then emit "DRY_RUN: $*"; else "$@"; fi; }

stage() { # $1 = LOG|WRITE, rest = the effect's argv, kept exact by the count
  STAGED_EFFECTS+=("$#" "$@")
}

log() { if [ "$STAGING" = true ]; then stage LOG "$@"; else emit "$@"; fi; }
run() { if [ "$STAGING" = true ]; then stage WRITE "$@"; else apply "$@"; fi; }

commit_staged_effects() {
  # In staging order, so a completed pass's log and writes read exactly as
  # they did when each acted at its own call site. The `>/dev/null` is the one
  # every `run` call site already applies: a redirection cannot travel with
  # the argv, so it is applied here instead — uniformly, because on this
  # surface every staged write has it.
  local i=0 argc
  STAGING=false
  while [ "$i" -lt "${#STAGED_EFFECTS[@]}" ]; do
    argc="${STAGED_EFFECTS[i]}"
    if [ "${STAGED_EFFECTS[i + 1]}" = LOG ]; then
      emit "${STAGED_EFFECTS[@]:i + 2:argc - 1}"
    else
      apply "${STAGED_EFFECTS[@]:i + 2:argc - 1}" >/dev/null
    fi
    i=$((i + 1 + argc))
  done
  STAGED_EFFECTS=()
}

skip_issue() { # $1 = issue, $2 = the whole reason clause — ends this issue's pass
  # Leaves the issue exactly as it is: nothing is derived from a read that
  # did not answer, and nothing this pass staged is ever committed — `exit`
  # discards the subshell that holds the buffer. So a skip implies zero
  # `gh issue edit`, zero `gh issue comment`, and no log line claiming an
  # effect that never landed, wherever in the pass the failed read lives.
  # Called from the read itself, so no call site can forget to check — which
  # is why it exits rather than returns. The reason rides its own
  # `#$n:`-prefixed line (#247 D5), emitted directly: the skip is a fact
  # about the pass, not one of the effects the pass staged.
  emit "#$1: skipped this pass — $2"
  exit "$ISSUEFLOW_SKIP"
}

load_issueflow_config() { # $1 = labels.conf
  local conf="$1" line seen=false
  [ -f "$conf" ] || { echo "issueflow: missing config: $conf" >&2; return 1; }
  TRIAGE_ACTORS=()
  while IFS= read -r line || [ -n "$line" ]; do
    case "$line" in
      triage-actors=*)
        [ "$seen" = false ] || {
          echo "issueflow: duplicate triage-actors line in $conf" >&2
          return 1
        }
        seen=true
        read -r -a TRIAGE_ACTORS <<<"${line#triage-actors=}"
        [ "${#TRIAGE_ACTORS[@]}" -gt 0 ] || {
          echo "issueflow: triage-actors must name at least one actor in $conf" >&2
          return 1
        }
        ;;
    esac
  done <"$conf"
  [ "$seen" = true ] || {
    echo "issueflow: missing triage-actors= line in $conf" >&2
    return 1
  }
}

is_triage_actor() {
  local actor
  for actor in "${TRIAGE_ACTORS[@]}"; do
    [ "$actor" = "$1" ] && return 0
  done
  return 1
}

has_issue_label() { grep -qxF "$1" <<<"$ISSUE_LABELS"; }

queue_decision() { # labels on stdin -> KEEP | ADD_NEEDS_TRIAGE | FLAG_CONFLICT
  local labels count=0 label categories=0
  labels="$(cat)"
  grep -qxF needs-triage <<<"$labels" && categories=$((categories + 1))
  grep -qxF epic <<<"$labels" && categories=$((categories + 1))
  for label in "${QUEUE_LABELS[@]}"; do
    if grep -qxF "$label" <<<"$labels"; then count=$((count + 1)); fi
  done
  [ "$count" -gt 0 ] && categories=$((categories + 1))
  if [ "$categories" -eq 0 ]; then echo ADD_NEEDS_TRIAGE
  elif [ "$categories" -gt 1 ] || [ "$count" -gt 1 ]; then echo FLAG_CONFLICT
  else echo KEEP
  fi
}

author_decision() { # $1 = true when author is triage; labels on stdin
  local triage="$1" labels
  labels="$(cat)"
  if [ "$triage" = false ] && ! grep -qxF needs-triage <<<"$labels"; then
    echo ADD_NEEDS_TRIAGE
  else echo KEEP
  fi
}

claim_decision() { # $1 assignee count, $2 linked open PR, $3 age seconds
  local assignees="$1" open_pr="$2" age="$3"
  # Staleness wins over missing ownership: a stale unassigned claim is
  # derivably reclaimable, while a recent unassigned claim needs triage.
  if [ "$open_pr" = false ] && [ "$age" -gt "$STALE_AFTER" ]; then echo RECLAIM
  elif [ "$assignees" -eq 0 ]; then echo FLAG_UNASSIGNED
  else echo KEEP
  fi
}

claim_clock_exempt() { # labels on stdin -> EXEMPT | SWEEP
  local labels
  labels="$(cat)"
  # Cross-repo work has no local closing PR by construction (#68), so its
  # deliberate silence must share the one claim-clock gate with rulings.
  if grep -qxF offsite <<<"$labels" \
    || [ "$(ruling_stale_exempt <<<"$labels")" = EXEMPT ]; then
    echo EXEMPT
  else
    echo SWEEP
  fi
}

claim_decision_at() { # $1 assignee count, $2 linked open PR, $3 last activity epoch
  claim_decision "$1" "$2" "$((NOW - $3))"
}

claim_reclaim_marker() { # $1 = last activity epoch
  printf 'claim-reclaimed-%s\n' "$1"
}

refs_references() { # PR body on stdin -> local issue numbers named by Refs
  awk '
    {
      line = $0
      lower = tolower(line)
      if (match(lower, /(^|[^[:alnum:]_-])refs[[:space:]:]+/)) {
        line = substr(line, RSTART + RLENGTH)
        if (line ~ /^(#|([[:alnum:]_.-]+\/)?[[:alnum:]_.-]+#)[0-9]+/) {
          sub(/[.(;].*/, "", line)
          print line
        }
      }
    }
  ' | issue_references \
    | awk -F '\t' '$1 == "LOCAL" { print $2 }' | sort -nu
}

open_pr_issues() { # records on stdin: CLOSING|BODY<TAB>value -> issue numbers
  local kind value
  while IFS=$'\t' read -r kind value; do
    case "$kind" in
      CLOSING) [ -n "$value" ] && printf '%s\n' "$value" ;;
      BODY) refs_references <<<"$value" ;;
    esac
  done | sort -nu
}

unchecked_criteria() { # issue body on stdin -> unchecked task-list lines verbatim
  awk '
    /^[[:space:]]*([-*]|[0-9]+\.)[[:space:]]+\[[[:space:]]\]/ {
      sub(/\r$/, "")
      print
    }
  '
}

post_merge_decision() { # $1 merged Refs PR, $2 linked open PR, $3 already handled
  local merged="$1" open_pr="$2" handled="$3" unchecked
  unchecked="$(cat)"
  if [ -n "$merged" ] && [ "$open_pr" = false ] && [ "$handled" = false ] \
      && [ -n "$unchecked" ]; then echo TRANSITION
  else echo KEEP
  fi
}

post_merge_pr_for_issue() { # $1 issue; records are ISSUE<TAB>PR<TAB>MERGED_AT
  # The deliverable is the PR that merged last, not the one numbered highest.
  # Merge order is not number order in this family: crew#176's two Refs PRs
  # merged #184 at 19:05:16Z and #182 at 19:05:18Z — the higher number two
  # seconds earlier. Number order is also what spends a marker on the wrong
  # PR: crew#321 carries `post-merge-transition-pr-326` while its real
  # deliverable crew#322 — a lower number, merging later — is still open, so
  # under the old rule the transition it owes could never fire (#242).
  # mergedAt is ISO-8601 UTC, so it sorts as a string; ties break by highest
  # PR number so the answer never depends on input order.
  awk -F '\t' -v issue="$1" '$1 == issue { print $3 "\t" $2 }' \
    <<<"${MERGED_REF_PR_RECORDS:-}" \
    | sort -t $'\t' -k1,1 -k2,2n | tail -n1 | cut -f2
}

post_merge_transition_marker() { # $1 merged PR number
  printf 'post-merge-transition-pr-%s\n' "$1"
}

issue_references() { # text on stdin -> LOCAL/CROSS<TAB>reference
  # A qualified reference belongs to another repository. Classify the whole
  # token before extracting numbers so rig#112 can never become local #112.
  { grep -Eo '([[:alnum:]_.-]+/)?[[:alnum:]_.-]+#[0-9]+|#[0-9]+' || true; } \
    | awk '
      index($0, "#") == 1 { print "LOCAL\t" substr($0, 2); next }
      { print "CROSS\t" $0 }
    '
}

blocked_reference_records() { # body on stdin -> classified reference records
  # Every occurrence of the marker contributes a clause. Binding to the first
  # occurrence alone dropped the later sentences of a repeated declaration
  # ("Blocked by #152. Blocked by #153. Blocked by #148 — …") and let earlier
  # prose that merely mentioned being blocked hijack the parse — the false
  # `ready` promotion on rig#154 (#184). Each clause runs to its own first
  # sentence terminator; declarations sometimes soft-wrap after a comma, so
  # an open clause continues across lines, and if prose omits the terminator
  # it retains to end of input. Unioning can over-retain — prose like "this
  # was blocked by #9 before the split" now contributes #9 — and that is the
  # correct direction of error: a stale `blocked` is a triage comment away,
  # a false `ready` sends a builder into work that cannot merge (#184).
  awk '
    BEGIN { marker = "blocked by" }
    {
      line = $0
      while (1) {
        if (!active) {
          start = index(tolower(line), marker)
          if (!start) next
          line = substr(line, start + length(marker))
          active = 1
        }
        if (match(line, /[.;]/)) {
          print substr(line, 1, RSTART - 1)
          line = substr(line, RSTART + 1)
          active = 0
        } else {
          print line
          next
        }
      }
    }
  ' | issue_references
}

blocked_references() { # body on stdin -> local issue numbers, one per line
  blocked_reference_records | awk -F '\t' '$1 == "LOCAL" { print $2 }' | sort -nu
}

blocked_cross_references() { # body on stdin -> qualified refs, one per line
  blocked_reference_records | awk -F '\t' '$1 == "CROSS" { print $2 }' | sort -u
}

blocked_parse_set() { # $1 local refs, $2 cross refs -> "{#7, #12}" | "{}"
  # The parse, rendered once. The comment, the marker and the log line all
  # read this one string, so the three can never disagree about what the
  # machine read. Both classes are shown because both are parsed: the locals
  # in the numeric order blocked_references answers, then the qualified
  # references blocked_cross_references answers — a cross-repo clause is as
  # capable of being readable-but-wrong as a local one.
  local rendered
  rendered="$(
    { [ -z "$1" ] || awk '{ print "#" $0 }' <<<"$1"
      [ -z "${2:-}" ] || printf '%s\n' "$2"
    } | awk '{ printf "%s%s", (NR > 1 ? ", " : ""), $0 } END { printf "\n" }'
  )"
  printf '{%s}\n' "$rendered"
}

blocked_parse_marker() { # $1 rendered set -> the echo's idempotency marker
  # Scoped to the SET's value, not to the issue and not to the sweep: the
  # marker names WHAT was echoed, and blocked_parse_echo_needed decides whether
  # it is still what the thread is saying.
  #
  # The identity is the DIGEST, not the slug beside it. Slugging is many-to-one
  # — `{acme/widgets#9}` and `{acme-widgets#9}` are both parses this reconciler
  # accepts, and both slug to `acme-widgets-9` — so a slug-keyed marker lets a
  # changed set find the old marker and say nothing, silence in precisely the
  # case the echo exists to speak about. Distinguishing `/` would close that
  # pair and leave the class: `-`, `_` and `.` are legal in a qualifier token
  # and all collapse the same way. The slug stays in front so a human reading
  # the raw comment can still see which set it belongs to; it decides nothing.
  local slug digest
  slug="$(printf '%s' "$1" | tr -c '[:alnum:]' '-' | sed 's/--*/-/g; s/^-//; s/-$//')"
  digest="$(printf '%s' "$1" | sha256sum | cut -c1-12)"
  printf 'blockers-parsed-%s-%s\n' "${slug:-none}" "$digest"
}

blocked_parse_echo_needed() { # $1 issue, $2 this parse's marker → 0 echo, 1 quiet
  # Idempotency for the parse echo is against the LAST parse echo on the
  # thread, not against any historical one. ensure_comment's any-occurrence
  # grep is right for a flag like `blocked-unparseable`, whose question is
  # "have I ever said this"; it is wrong for a value that changes, whose
  # question is "is this still what I am saying". The difference is A -> B -> A:
  # under an any-occurrence search the return to A finds A's own first echo and
  # stays silent, leaving the thread's most recent echo asserting B while the
  # sweep gates on A. A stale parse presented as the current one is the exact
  # failure #252 exists to kill, and the third edit changed the parsed set, so
  # the criterion says it speaks.
  #
  # Comparing markers rather than re-rendering the last set keeps the digest as
  # the only identity: two sets are the same here iff blocked_parse_marker says
  # so, the same rule the marker itself is built on.
  local bodies last
  guarded_read bodies gh api --paginate "repos/$REPO/issues/$1/comments" --jq '.[].body' \
    || skip_issue "$1" "could not read its comments: $(read_failure_reason "$READ_FAILURE_STDERR")"
  # The read fails closed above (#247 D1): an unreadable history skips the
  # issue rather than answering "nothing echoed yet" and re-posting.
  last="$(grep -o '<!-- issueflow:blockers-parsed-[[:alnum:]-]* -->' <<<"$bodies" | tail -n 1)"
  [ "$last" != "<!-- issueflow:$2 -->" ]
}

blocked_decision() { # $1 local refs, $2 OPEN/CLOSED states, $3 cross-repo refs
  local refs="$1" states="$2" cross_refs="${3:-}"
  if [ -n "$cross_refs" ]; then echo FLAG_CROSS_REPO
  elif [ -z "$refs" ]; then echo FLAG_UNPARSEABLE
  elif grep -qxF OPEN <<<"$states"; then echo KEEP
  elif grep -qxF UNKNOWN <<<"$states"; then echo FLAG_UNPARSEABLE
  else echo READY
  fi
}

epic_references() { # markdown task-list issue references from body on stdin
  awk '
    tolower($0) ~ /^##[[:space:]]+task list[[:space:]]*$/ { in_list = 1; next }
    in_list && /^#/ { exit }
    in_list && /^[[:space:]]*[-*][[:space:]]+\[[ xX]\]/ { print }
  ' | issue_references \
    | awk -F '\t' '$1 == "LOCAL" { print $2 }' | sort -nu
}

epic_decision() { # $1 refs, $2 states
  local refs="$1" states="$2"
  if [ -n "$refs" ] && ! grep -Eq '^(OPEN|UNKNOWN)$' <<<"$states"; then echo NUDGE
  else echo KEEP
  fi
}

offsite_cross_referenced_prs() { # timeline JSON on stdin -> owner/repo#N
  jq -r '
    .[]
    | select(.event == "cross-referenced")
    | .source.issue
    | select(.pull_request != null)
    | select(.repository.full_name != null and .number != null)
    | "\(.repository.full_name)#\(.number)"
  ' | sort -u
}

offsite_resolved_decision() { # PR states on stdin -> NUDGE | QUIET
  local states
  states="$(cat)"
  if [ -n "$states" ] && ! grep -Eq '^(OPEN|UNKNOWN)$' <<<"$states"; then
    echo NUDGE
  else
    echo QUIET
  fi
}

issue_payload_valid() { # $1 = the requested issue; payload on stdin
  # The second of D3's two required guards, and neither subsumes the other.
  # The status check catches the 504 whose body is GitHub's JSON error object
  # — valid JSON that passes every jq guard and empties the label set. THIS
  # one catches an HTTP 200 whose body is `null`, which exits 0 and empties it
  # just the same. `.number` is checked against the issue asked for, so a
  # payload about some other issue can never be reconciled as this one.
  jq -e --arg n "$1" '
    type == "object" and (.number | tostring) == $n and (.labels | type) == "array"
  ' >/dev/null 2>&1
}

skipped_tail() { # $1 = skip count, $2 = the issue numbers → the D6 line, or nothing
  # `reconciled.` stays byte-identical when the pass was whole — tests pin that
  # exact string, and #101 D1 is the precedent for not folding new text into a
  # matched line. A partial pass says so on a line of its own, after it, so a
  # consumer reading only the tail of a job log can see it.
  [ "$1" -gt 0 ] || return 0
  if [ "$1" -eq 1 ]; then
    printf '%s issue skipped this pass on an unreadable fact: %s\n' "$1" "$2"
  else
    printf '%s issues skipped this pass on unreadable facts: %s\n' "$1" "$2"
  fi
}

# API edge. Marker comments make warnings and nudges idempotent across sweeps.
ensure_comment() { # $1 issue, $2 marker, $3 message
  local n="$1" marker="$2" message="$3"
  if issue_comment_has_marker "$n" "$marker"; then return; fi
  run gh issue comment "$n" -R "$REPO" --body "<!-- issueflow:$marker -->
$message" >/dev/null
}

issue_comment_has_marker() { # $1 issue, $2 marker → 0 found, 1 genuinely absent
  # A failed read used to answer "no marker", which re-posts the comment the
  # marker exists to suppress — absence of evidence read as evidence of
  # absence (#247 D1). It cannot be a return value: every caller treats
  # non-zero as "absent", so the skip is taken here, at the read.
  local bodies
  guarded_read bodies gh api --paginate "repos/$REPO/issues/$1/comments" --jq '.[].body' \
    || skip_issue "$1" "could not read its comments: $(read_failure_reason "$READ_FAILURE_STDERR")"
  grep -qF "<!-- issueflow:$2 -->" <<<"$bodies"
}

reference_states() {
  local ref state
  while IFS= read -r ref; do
    [ -n "$ref" ] || continue
    state="$(gh api "repos/$REPO/issues/$ref" --jq '.state' 2>/dev/null || echo UNKNOWN)"
    case "$state" in open) echo OPEN ;; closed) echo CLOSED ;; *) echo UNKNOWN ;; esac
  done
}

offsite_pr_states() {
  local ref repo number state
  while IFS= read -r ref; do
    [ -n "$ref" ] || continue
    repo="${ref%#*}"
    number="${ref##*#}"
    state="$(gh api "repos/$repo/pulls/$number" --jq '.state' 2>/dev/null || echo UNKNOWN)"
    case "$state" in open) echo OPEN ;; closed) echo CLOSED ;; *) echo UNKNOWN ;; esac
  done
}

offsite_timeline() { # unreadable timelines are deliberately silent
  gh api --paginate "repos/$REPO/issues/$1/timeline" 2>/dev/null || return 1
}

issue_activity_at() { # $1 issue, $2 created_at, $3 with-assignment|comments-only
  # One body, two clocks over it — a second activity computation is the drift
  # the reuse exists to prevent, and the two callers below are the whole
  # difference between them.
  #
  # Both reads are checked, and a failure reports rather than answering an age
  # (#247 D1). Swallowed, the comments read falls back to `created_at`, and a
  # `claimed` issue created months ago but commented on seconds earlier is
  # reclaimed — the live builder unassigned, under a comment asserting 48
  # hours of silence. `needs-triage` is cheap to remove; that is not.
  # gh's stderr is left to flow to this function's own, where the caller's
  # guarded_read captures it for the reason line.
  local n="$1" created="$2" mode="$3" comments timeline="" latest
  comments="$(gh api --paginate "repos/$REPO/issues/$n/comments" --jq '.[].created_at')" \
    || return 1
  if [ "$mode" = with-assignment ]; then
    timeline="$(gh api --paginate "repos/$REPO/issues/$n/timeline" \
      --jq '.[] | select(.event == "assigned") | .created_at')" || return 1
  fi
  latest="$(printf '%s\n%s\n%s\n' "$created" "$comments" "$timeline" | sort | tail -n1)"
  date -d "$latest" +%s
}

last_issue_activity() { # $1 issue, $2 created_at → epoch; non-zero if a read failed
  # The claim clock, and the ruling clock with it. Assignment is the claim
  # itself. Ignoring it would let an old issue be reclaimed in the seconds
  # between assignment and its required draft PR.
  issue_activity_at "$1" "$2" with-assignment
}

last_issue_comment_activity() { # $1 issue, $2 created_at → epoch; non-zero on a failed read
  # The evidence nudge's clock (#254). Same computation, one input fewer, and
  # the input it drops is the one that would starve the criterion: on
  # `post-merge` there is no claim for an assignment to protect, and an
  # assignee there is the invalid composition the `post-merge-assigned` flag
  # reports. Counting it would let a broken board buy the item another 7 days
  # of silence — the failure direction of #254 taken backwards.
  #
  # A comment the sweep itself wrote is still activity here, deliberately:
  # the nudge carries no marker, so its own comment is what rate-limits it,
  # and no machine comment can be exempted without exempting that one too.
  # Reading authorship back into the clock would mean a body read this issue
  # forbids.
  issue_activity_at "$1" "$2" comments-only
}

reconcile_issue() {
  local n="$1" decision refs cross_refs states age evidence_age created assignees open_pr=false label owners
  local merged_ref_pr="" transition_marker="" transition_handled=false parsed_set="" parse_marker=""
  local unchecked="" remove_claimed=claimed
  local attention_active=true attention_suppression=""
  decision="$(queue_decision <<<"$ISSUE_LABELS")"
  case "$decision" in
    ADD_NEEDS_TRIAGE)
      run gh issue edit "$n" -R "$REPO" --add-label needs-triage >/dev/null
      log "#$n: needs-triage (no queue state)" ;;
    FLAG_CONFLICT)
      ensure_comment "$n" queue-conflict \
        'The issue-flow sweep found conflicting queue labels. It cannot infer intent safely; triage must leave exactly one of `needs-triage`, `epic`, `ready`, `claimed`, `blocked`, or `post-merge`.'
      log "#$n: conflicting queue labels; flagged"
      return ;;
  esac

  if has_issue_label claimed; then
    assignees="$(jq '.assignees | length' <<<"$ISSUE_JSON")"
    grep -qxF "$n" <<<"${OPEN_PR_ISSUES:-}" && open_pr=true
    merged_ref_pr="$(post_merge_pr_for_issue "$n")"
    if [ -n "$merged_ref_pr" ]; then
      transition_marker="$(post_merge_transition_marker "$merged_ref_pr")"
      issue_comment_has_marker "$n" "$transition_marker" \
        && transition_handled=true
    fi
    unchecked="$(unchecked_criteria <<<"$(jq -r '.body // ""' <<<"$ISSUE_JSON")")"
    if [ "$(post_merge_decision "$merged_ref_pr" "$open_pr" "$transition_handled" \
        <<<"$unchecked")" = TRANSITION ]; then
      ensure_comment "$n" "$transition_marker" \
        "The Refs-linked PR merged with these acceptance criteria still unchecked:

$unchecked

The merge releases the claim; no builder owes a draft. Triage owes completion in a follow-up comment that names the owner and wake condition."
      owners="$(jq -r '[.assignees[].login] | join(",")' <<<"$ISSUE_JSON")"
      # `attention` is a demand for the assigned builder. The derived
      # transition releases that builder, so carrying the demand forward
      # would create an impossible parked-for state (#175 D4).
      has_issue_label attention && remove_claimed=claimed,attention
      if [ -n "$owners" ]; then
        run gh issue edit "$n" -R "$REPO" --remove-assignee "$owners" \
          --remove-label "$remove_claimed" --add-label post-merge >/dev/null
      else
        run gh issue edit "$n" -R "$REPO" \
          --remove-label "$remove_claimed" --add-label post-merge >/dev/null
      fi
      log "#$n: merged Refs PR -> post-merge; claim released"
      attention_active=false
    else
      created="$(jq -r '.created_at' <<<"$ISSUE_JSON")"
      guarded_read age last_issue_activity "$n" "$created" \
        || skip_issue "$n" "could not read its activity history: $(read_failure_reason "$READ_FAILURE_STDERR")"
      if [ "$(claim_clock_exempt <<<"$ISSUE_LABELS")" = EXEMPT ]; then
        # Legitimately quiet work does not run the reclaim clock. Only the
        # clock stops: an unassigned claim is still a repair the decision must
        # see, so it runs on a zero age rather than being skipped.
        decision="$(claim_decision "$assignees" "$open_pr" 0)"
      else
        decision="$(claim_decision_at "$assignees" "$open_pr" "$age")"
      fi
      case "$decision" in
        FLAG_UNASSIGNED)
          ensure_comment "$n" claimed-unassigned \
            'This issue is `claimed` but has no assignee. The sweep cannot infer an owner; triage must repair the claim.' ;;
        RECLAIM)
          # The last-activity epoch identifies a claim episode. A fixed marker
          # hid the required comment when the same issue was later claimed and
          # reclaimed again.
          ensure_comment "$n" "$(claim_reclaim_marker "$age")" \
            'This claim has no linked open PR and no activity for 48 hours. The sweep is reclaiming it for the ready queue.'
          owners="$(jq -r '[.assignees[].login] | join(",")' <<<"$ISSUE_JSON")"
          if [ -n "$owners" ]; then
            run gh issue edit "$n" -R "$REPO" --remove-assignee "$owners" \
              --remove-label claimed --add-label ready >/dev/null
          else
            run gh issue edit "$n" -R "$REPO" --remove-label claimed --add-label ready >/dev/null
          fi
          log "#$n: stale claim reclaimed -> ready" ;;
      esac
      [ "$decision" != FLAG_UNASSIGNED ] || attention_suppression=claimed-unassigned
      if has_issue_label offsite; then
        local timeline
        if timeline="$(offsite_timeline "$n")"; then
          refs="$(offsite_cross_referenced_prs <<<"$timeline")"
          states="$(offsite_pr_states <<<"$refs")"
          if [ "$(offsite_resolved_decision <<<"$states")" = NUDGE ]; then
            ensure_comment "$n" offsite-resolved \
              "$(tr '\n' ' ' <<<"$refs" | sed 's/[[:space:]]*$//') is closed; this issue's \`offsite\` flag is still up. Clear it and close the issue, or say what is still outstanding. @$(jq -r '.assignees[0].login' <<<"$ISSUE_JSON")"
            log "#$n: resolved offsite PRs nudged"
          fi
        fi
      fi
    fi
  elif has_issue_label post-merge; then
    assignees="$(jq '.assignees | length' <<<"$ISSUE_JSON")"
    # The evidence nudge's clock is read BEFORE any comment this branch
    # posts. `ensure_comment` below is itself activity, so reading after it
    # would let the assigned-flag comment silence the nudge for another 7
    # days — the same self-silencing the ruling nudge avoids by reading its
    # facts once, at the top of the pass.
    #
    # Its own variable, not `age`: the ruling block below reuses `age` when
    # it is already set, and the evidence clock is deliberately narrower than
    # the ruling clock. Leaking it there would silently change what a ruling
    # nudge means depending on which queue label the issue sits under.
    created="$(jq -r '.created_at' <<<"$ISSUE_JSON")"
    guarded_read evidence_age last_issue_comment_activity "$n" "$created" \
      || skip_issue "$n" "could not read its activity history: $(read_failure_reason "$READ_FAILURE_STDERR")"
    # The ruling clock is read HERE, not in the ruling block, for the same
    # reason the evidence clock is: that block reads only when `age` is
    # unset, and by the time it runs this branch may have posted the
    # evidence nudge — so its read would date the issue by this sweep's own
    # comment and silence the ruling nudge. Both waits are answered from
    # facts that predate anything this pass writes. The cost is one extra
    # comments read on `post-merge` + `needs-ruling`, and only there: an
    # ordinary `post-merge` issue reads once.
    if has_issue_label needs-ruling; then
      guarded_read age last_issue_activity "$n" "$created" \
        || skip_issue "$n" "could not read its activity history: $(read_failure_reason "$READ_FAILURE_STDERR")"
    fi
    if [ "$assignees" -gt 0 ] || has_issue_label attention; then
      ensure_comment "$n" post-merge-assigned \
        'This `post-merge` issue has an assignee or `attention`. The sweep will not undo hand-set intent; triage must clear the invalid composition or move the issue back into buildable queue state.'
      log "#$n: assigned or attention-bearing post-merge issue flagged"
    fi
    attention_suppression=post-merge-assigned
    # ---- the post-merge evidence nudge (#254), the ruling nudge's twin ----
    # A `post-merge` item waits on named evidence with a named owner, and
    # nothing nudged when the wait went quiet: crew#181's real-host criterion
    # starved four separate times across two releases, crew#240/#264 sat
    # until an operator happened to run the right read. Same 7-day rule, same
    # constant, same no-marker property — `ruling_nudge_decision` is the one
    # spelling of all three (lib/ruling.sh), and a second `7 * 24 * 3600`
    # here is the drift that file exists to prevent.
    #
    # The addressee is the triage actor, not `HUMAN_REVIEWER`: `post-merge`
    # is triage's completion queue by contract (TRIAGE.md), so a starving
    # wake condition is triage's to answer, and routing it to the operator
    # asks the wrong party for a move it does not owe. `triage-actors=` is
    # mandatory config — `load_issueflow_config` refuses to run without it —
    # so there is nothing to fall back to, and a silent fallback is exactly
    # how the wrong addressee comes back.
    if [ "$(ruling_nudge_decision "$NOW" "$evidence_age")" = NUDGE ]; then
      local quiet_days=$(((NOW - evidence_age) / 86400))
      run gh issue comment "$n" -R "$REPO" --body "@${TRIAGE_ACTORS[0]} — this \`post-merge\` item has had no activity for ${quiet_days} days: https://github.com/$REPO/issues/$n

Its wake evidence is still owed. \`post-merge\` means the merge landed and
triage owns completion — judge the remaining criteria against the evidence
and close the issue, or say what is still outstanding and who owes it. The
sweep names no criterion: which one starved is prose, and the machine never
judges prose (the link is the payload).

*This nudge is comment-only and carries no idempotency marker on purpose: the comment itself is activity, so posting it resets the 7-day window and the rule self-rate-limits to one nudge per 7 quiet days. Do not add a marker.*" >/dev/null
      log "#$n: post-merge evidence nudge (${quiet_days}d quiet — triage owes the wake evidence)"
    fi
  elif has_issue_label blocked; then
    refs="$(blocked_references <<<"$(jq -r '.body // ""' <<<"$ISSUE_JSON")")"
    cross_refs="$(blocked_cross_references <<<"$(jq -r '.body // ""' <<<"$ISSUE_JSON")")"
    # The parse is echoed before any verdict is derived from it (#252). The
    # clause parse is exact and unforgiving, and its output was invisible:
    # crew#308 silently parsed a negated "no longer blocked by #221" as a
    # blocker, crew#71 spent five days as an unresolvable queue conflict, and
    # crew#284's declaration had to be re-derived by hand-running the parser.
    # Every one of those was found by a human running the parser, hours or
    # days late. `blocked-unparseable` already catches the UNREADABLE
    # declaration; this catches the readable-but-wrong one, which no flag can
    # detect because the machine cannot judge what a human meant — only state
    # what it read, and let the human see the divergence in one sweep.
    #
    # The illustrative `#9` in the body below is code-spanned for the same
    # reason `blocked-unparseable` code-spans its `Blocked by #N`: an
    # unbackticked `#N` in a comment this sweep posts on a cron linkifies, and
    # writes a "mentioned in" event onto an unrelated issue once per echo.
    parsed_set="$(blocked_parse_set "$refs" "$cross_refs")"
    parse_marker="$(blocked_parse_marker "$parsed_set")"
    if blocked_parse_echo_needed "$n" "$parse_marker"; then
      run gh issue comment "$n" -R "$REPO" --body "<!-- issueflow:$parse_marker -->
This issue's \`Blocked by\` declarations parse to: $parsed_set

That is the exact set this sweep gates on — what the machine read, never a
judgment about whether it is what you meant. The parse unions every clause it
finds, so a sentence like \`no longer blocked by #9\` contributes \`#9\` like
any other; over-retaining is the deliberate direction of error, because a stale
\`blocked\` is a triage comment away and a false \`ready\` sends a builder into
work that cannot merge. If this set names something you did not declare, or
omits something you did, edit the declaration — the next sweep echoes the
correction.

*Comment only: nothing on this path writes a label. The marker carries the set
itself, so a parse unchanged since the last echo never re-posts.*" >/dev/null
    fi
    log "#$n: blocked declarations parse to $parsed_set"
    states="$(reference_states <<<"$refs")"
    decision="$(blocked_decision "$refs" "$states" "$cross_refs")"
    case "$decision" in
      FLAG_CROSS_REPO)
        ensure_comment "$n" blocked-cross-repo \
          "This issue's \`Blocked by\` declaration names cross-repo dependencies that the sweep cannot resolve: $(tr '\n' ' ' <<<"$cross_refs" | sed 's/[[:space:]]*$//'). Triage must verify those dependencies and flip this issue to \`ready\` by hand." ;;
      FLAG_UNPARSEABLE)
        ensure_comment "$n" blocked-unparseable \
          'This issue is `blocked`, but its body has no parseable `Blocked by #N` declaration. The sweep will not guess the dependency.' ;;
      READY)
        ensure_comment "$n" blockers-cleared \
          'Every issue named by `Blocked by` is closed. The sweep is moving this issue to `ready`.'
        run gh issue edit "$n" -R "$REPO" --remove-label blocked --add-label ready >/dev/null
        log "#$n: blockers closed -> ready" ;;
    esac
  elif has_issue_label epic; then
    refs="$(epic_references <<<"$(jq -r '.body // ""' <<<"$ISSUE_JSON")")"
    states="$(reference_states <<<"$refs")"
    if [ "$(epic_decision "$refs" "$states")" = NUDGE ]; then
      ensure_comment "$n" epic-complete \
        "Every issue referenced by this epic's task list is closed. Please close the epic or extend its task list."
      log "#$n: completed epic nudged"
    fi
  fi

  # The flag composes with every build queue state, but requires an assignee.
  # Existing post-merge/claimed diagnostics take precedence so one board bug
  # draws one comment (#232 D5); the shared helper still logs the suppression.
  if [ "$attention_active" = true ] && has_issue_label attention; then
    [ -n "${assignees:-}" ] || assignees="$(jq '.assignees | length' <<<"$ISSUE_JSON")"
    reconcile_attention "$n" issue "$assignees" "$attention_suppression"
  fi

  # ---- the ruling invariants (#52), on any queue state ----
  # The flag composes with the queue labels (#50 D8), so this runs after the
  # queue branches rather than inside one of them. The FLAG_CONFLICT return
  # above still short-circuits it on purpose: a board lying about its queue
  # state is repaired by triage before anything else is derived from it.
  if has_issue_label needs-ruling; then
    # An already-applied stale comes off: waiting on a human is legitimately
    # quiet (#50 D10), and nothing on the issue side ever puts stale back.
    if has_issue_label stale; then
      run gh issue edit "$n" -R "$REPO" --remove-label stale >/dev/null
      log "#$n: unstale (a ruling is pending)"
    fi
    if [ -z "${age:-}" ]; then
      created="$(jq -r '.created_at' <<<"$ISSUE_JSON")"
      guarded_read age last_issue_activity "$n" "$created" \
        || skip_issue "$n" "could not read its activity history: $(read_failure_reason "$READ_FAILURE_STDERR")"
    fi
    reconcile_ruling "$n" "$age" "$NOW"
  fi
}

reconcile_opened_issue() {
  local n="$1" author triage=false labels remove="" label
  ISSUE_JSON="$(gh api "repos/$REPO/issues/$n")"
  # The stand-downs return 0 explicitly: a bare return carries the failed
  # test's status, which under execution is live `set -e` — and it killed the
  # run on every triage-authored mint, before one issue was reconciled (#91).
  jq -e 'has("pull_request") | not' <<<"$ISSUE_JSON" >/dev/null || return 0
  author="$(jq -r '.user.login' <<<"$ISSUE_JSON")"
  is_triage_actor "$author" && triage=true
  labels="$(jq -r '.labels[].name' <<<"$ISSUE_JSON")"
  [ "$(author_decision "$triage" <<<"$labels")" = ADD_NEEDS_TRIAGE ] || return 0
  for label in epic "${QUEUE_LABELS[@]}"; do
    grep -qxF "$label" <<<"$labels" && remove="$remove,$label"
  done
  remove="${remove#,}"
  if [ -n "$remove" ]; then
    run gh issue edit "$n" -R "$REPO" --add-label needs-triage --remove-label "$remove" >/dev/null
  else
    run gh issue edit "$n" -R "$REPO" --add-label needs-triage >/dev/null
  fi
  log "#$n: needs-triage (opened by $author)"
}

reconcile_issue_pass() { # $1 = issue — one issue's whole pass, in its own subshell
  # The subshell is #91's resilience: one unreadable or broken issue must not
  # take the sweep down. What it is NOT is an errexit boundary — a command
  # whose status is tested by `||` runs with errexit suppressed, and the
  # suppression extends through the whole subshell body, so the handler below
  # is what disables the errexit that would have caught a failed read (#247
  # D2). Removing it would revive errexit and lose #91. Explicit per-read
  # checks are the mechanism instead, and each one exits with ISSUEFLOW_SKIP.
  #
  # What the subshell IS, since #247's first round, is the atomicity
  # boundary: the staged effects live in it, so ending it — by a skip, or by
  # a crash — discards them, and no partial pass can ever reach the board.
  local n="$1" status=0
  (
    # Everything below stages rather than acts, and commits at the bottom —
    # so a skip taken at any read, and a crash at any statement, leaves the
    # issue exactly as it was (D1). `|| exit $?` keeps a crash's status the
    # subshell's own, as it was when reconcile_issue was the last command
    # here: the commit must not overwrite it, and must not run under it.
    STAGING=true
    guarded_read ISSUE_JSON gh api "repos/$REPO/issues/$n" \
      || skip_issue "$n" "could not read the issue: $(read_failure_reason "$READ_FAILURE_STDERR")"
    issue_payload_valid "$n" <<<"$ISSUE_JSON" \
      || skip_issue "$n" "the issue read answered a payload that is not issue #$n carrying a label array"
    jq -e 'has("pull_request") | not' <<<"$ISSUE_JSON" >/dev/null || exit 0
    ISSUE_LABELS="$(jq -r '.labels[].name' <<<"$ISSUE_JSON")"
    reconcile_issue "$n" || exit $?
    commit_staged_effects
  ) || status=$?
  if [ "$status" -eq "$ISSUEFLOW_SKIP" ]; then
    SKIPPED_COUNT=$((SKIPPED_COUNT + 1))
    SKIPPED_ISSUES="${SKIPPED_ISSUES:+$SKIPPED_ISSUES }#$n"
  elif [ "$status" -ne 0 ]; then
    # Byte-identical, and still owed: a skip is deliberate, a crash is not,
    # and folding the two together would hide one behind the other (D4).
    log "#$n: reconcile failed — continuing with the remaining issues"
  fi
}

main() {
  local owner name
  REPO="${REPO:?set REPO to owner/name}"
  LABELS_CONF="${LABELS_CONF:-.github/labels.conf}"
  load_issueflow_config "$LABELS_CONF"
  if [ "${EVENT_NAME:-}" = issues ] && [ "${EVENT_ACTION:-}" = opened ]; then
    reconcile_opened_issue "${EVENT_ISSUE:?set EVENT_ISSUE for issues:opened}"
  fi
  owner="${REPO%%/*}"
  name="${REPO#*/}"
  # crew#321 released a live claim because the open side read only closing
  # links while the merged side parsed Refs bodies. One parser now supplies
  # the local body references on both sides, so transition and reclaim agree.
  OPEN_PR_ISSUES="$(gh api graphql --paginate -f owner="$owner" -f name="$name" -f query='
    query($owner: String!, $name: String!, $endCursor: String) {
      repository(owner: $owner, name: $name) {
        pullRequests(first: 100, states: OPEN, after: $endCursor) {
          nodes { body closingIssuesReferences(first: 100) { nodes { number } } }
          pageInfo { hasNextPage endCursor }
        }
      }
    }' --jq '.data.repository.pullRequests.nodes[]
      | (.closingIssuesReferences.nodes[].number
          | ["CLOSING", tostring] | @tsv),
        ((.body // "") | split("\n")[] | ["BODY", .] | @tsv)' \
    | open_pr_issues)"
  MERGED_REF_PR_RECORDS="$(gh api graphql --paginate -f owner="$owner" -f name="$name" -f query='
    query($owner: String!, $name: String!, $endCursor: String) {
      repository(owner: $owner, name: $name) {
        pullRequests(first: 100, states: MERGED, after: $endCursor) {
          nodes { number mergedAt body }
          pageInfo { hasNextPage endCursor }
        }
      }
    }' --jq '.data.repository.pullRequests.nodes[]
      | .number as $pr | .mergedAt as $merged | .body | split("\n")[]
      | [$pr, $merged, .] | @tsv' \
    | while IFS= read -r record; do
        # Split on exact tabs rather than IFS: tab is IFS whitespace, so bash
        # collapses a run of them, and a middle column that ever came back
        # empty would silently shift the body one field left. The body is
        # arbitrary text and stays last, where the remainder belongs.
        pr="${record%%$'\t'*}"
        rest="${record#*$'\t'}"
        merged="${rest%%$'\t'*}"
        body="${rest#*$'\t'}"
        while IFS= read -r issue; do
          [ -n "$issue" ] && printf '%s\t%s\t%s\n' "$issue" "$pr" "$merged"
        done < <(refs_references <<<"$body")
      done)"

  local n tail_line
  SKIPPED_COUNT=0
  SKIPPED_ISSUES=""
  for n in $(gh api --paginate "repos/$REPO/issues?state=open&per_page=100" \
      --jq '.[] | select(has("pull_request") | not) | .number'); do
    reconcile_issue_pass "$n"
  done
  log "reconciled."
  # The job stays green (D7): an hourly sweep over a hundred-issue board meets
  # transient 504s as a matter of course, and reddening the whole run for one
  # skipped issue trains consumers to ignore red — the outcome #95 and #101
  # both steered away from on the PR surface. This line is what buys back the
  # auditability that costs.
  tail_line="$(skipped_tail "$SKIPPED_COUNT" "$SKIPPED_ISSUES")"
  [ -z "$tail_line" ] || log "$tail_line"
}

if [ "${BASH_SOURCE[0]}" = "$0" ]; then main "$@"; fi